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Tropospheric ozone behavior observed in Indonesia
Abstract
The variation of the surface and free tropospheric ozone has been observed at Watukosek (7.5°S, 112.6°E), Indonesia. This paper is to report the analysis of the ozonesonde data obtained during the period November 1992–June 1994. A seasonal variation of ozone is evident in the lower and middle troposphere, with the maximum occurring in September and October. In the upper troposphere, seasonal variation is not evident, but enhancements were occasionally detected in April, May and June. A common feature that ozone mixing ratio is nearly constant of 20–30 ppbv throughout the troposphere is identified as a basic type of altitude profile appearing in the wet season, December through March, and in the middle of the dry season, July and August. Two other features are occasionally found. One appearing in April, May and June exhibits an enhancement over 50 ppbv in the upper troposphere, and the other appearing in September and October exhibits an enhancement in the lower and middle troposphere.
... 4. Can mechanisms controlling tropospheric ozone in SHADOZ be deduced from week-to-week variability in profiles, trajectories, and other indicators of sources or [Swap et al., 2002] Polarstern cruises (1987,1988) [Smit et al., 1989;Weller et al., 1996], Aerosols99 cruise (1998 -1999) [Kondo et al., 2002] processes (Table 2) are made with balloon-borne ECC (electrochemical concentration cell) ozonesondes coupled with a standard radiosonde and a sensor for relative humidity [Komhyr, 1986;Komhyr et al., 1995]. At Watukosek, Java, prior to conversion to ECC sondes in August 1999, MEISEI sondes were used [Komala et al., 1996;Fujiwara et al., 2000;Kobayashi and Toyama, 1966]. Radiosondes produced by three manufacturers are used at SHADOZ stations; seven use the Vaisala manufactured sonde. ...
... At the transition elevated ozone was detected over Fiji ( Figure 5, top panel) and Watukosek (bottom panel). Although the Watukosek soundings (25 -28 DU in early 1998) are much less than the 55 DU recorded in October 1997 [Fujiwara et al., 1999], these values are greater than normal (compare January -March 1999 and 2000 in Figure 5) [see Komala et al., 1996]. ...
The first view of stratospheric and tropospheric ozone variability in the Southern Hemisphere tropics is provided by a 3-year record of ozone soundings from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network (http://croc.gsfc.nasa.gov/shadoz). Observations covering 1998–2000 were made over Ascension Island, Nairobi (Kenya), Irene (South Africa), Réunion Island, Watukosek (Java), Fiji, Tahiti, American Samoa, San Cristóbal (Galapagos), and Natal (Brazil). Total, stratospheric, and tropospheric column ozone amounts usually peak between August and November. Other features are a persistent zonal wave-one pattern in total column ozone and signatures of the quasi-biennial oscillation (QBO) in stratospheric ozone. The wave-one is due to a greater concentration of free tropospheric ozone over the tropical Atlantic than the Pacific and appears to be associated with tropical general circulation and seasonal pollution from biomass burning. Tropospheric ozone over the Indian and Pacific Oceans displays influences of the waning 1997–1998 El Niño, seasonal convection, and pollution transport from Africa. The most distinctive feature of SHADOZ tropospheric ozone is variability in the data, e.g., a factor of 3 in column amount at 8 of 10 stations. Seasonal and monthly means may not be robust quantities because statistics are frequently not Gaussian even at sites that are always in tropical air. Models and satellite retrievals should be evaluated on their capability for reproducing tropospheric variability and fine structure. A 1999–2000 ozone record from Paramaribo, Surinam (6°N, 55°W) (also in SHADOZ) shows a marked contrast to southern tropical ozone because Surinam is often north of the Intertropical Convergence Zone (ITCZ). A more representative tropospheric ozone climatology for models and satellite retrievals requires additional Northern Hemisphere tropical data.
... In Southeast Asia, especially in Indonesia, it has been recognized that emissions of ozone precursors, such as nitric oxide (NO), reactive nitrogen (NO y ), carbon monoxide (CO), and nonmethane hydrocarbons (NMHCs) by biomass burning in this region can significantly affect the ozone distribution. Ozonesonde observations have revealed the seasonal variation of tropospheric ozone over Indonesia, indicating that the ozone mixing ratio in the lower and middle troposphere increases in the late dry season (August to November), probably due to biomass burning [Komala et al., 1996;Fujiwara et al., 2000]. The observations also showed that the remarkably large ozone increase persisted between September and November in 1994 and 1997 when extensive forest fires occurred in Indonesia [Fujiwara et al., 1999]. ...
... The ozone mixing ratios over eastern and western Indonesia were also nearly constant (15 -25 ppbv) in the free troposphere above 3 km. These low and constant ozone mixing ratios in the free troposphere were less than those observed in the September -October period of other years when biomass burning occurred in Indonesia, but were similar to those in the wet season (December -March) [Komala et al., 1996;Fujiwara et al., 2000], consistent with the small biomass burning activity during BIBLE-A. On the contrary, the CO, NO y , C 2 H 6 , C 2 H 2 , and C 3 H 8 mixing ratios increased with altitude above 8 km over eastern and western Indonesia. ...
The Biomass Burning and Lightning Experiment phase A (BIBLE-A) aircraft observation campaign was conducted from 24 September to 10 October 1998, during a La Niña period. During this campaign, distributions of ozone and its precursors (NO, CO, and nonmethane hydrocarbons (NMHCs)) were observed over the tropical Pacific Ocean, Indonesia, and northern Australia. Mixing ratios of ozone and its precursors were very low at altitudes between 0 and 13.5 km over the tropical Pacific Ocean. The mixing ratios of ozone precursors above 8 km over Indonesia were often significantly higher than those over the tropical Pacific Ocean, even though the prevailing easterlies carried the air from the tropical Pacific Ocean to over Indonesia within several days. For example, median NO and CO mixing ratios in the upper troposphere were 12 parts per trillion (pptv) and 72 parts per billion (ppbv) over the tropical Pacific Ocean and were 83 pptv and 85 ppbv over western Indonesia, respectively. Meteorological analyses and high ethene (C2H4) mixing ratios indicate that the increase of the ozone precursors was caused by active convection over Indonesia through upward transport of polluted air, mixing, and lightning all within the few days prior to observation. Sources of ozone precursors are discussed by comparing correlations of some NMHCs and CH3Cl concentrations with CO between the lower and upper troposphere. Biomass burning in Indonesia was nearly inactive during BIBLE-A and was not a dominant source of the ozone precursors, but urban pollution and lightning contributed importantly to their increases. The increase in ozone precursors raised net ozone production rates over western Indonesia in the upper troposphere, as shown by a photochemical model calculation. However, the ozone mixing ratio (~20 ppbv) did not increase significantly over Indonesia because photochemical production of ozone did not have sufficient time since the augmentation of ozone precursors. Backward trajectories show that many air masses sampled over the ocean south of Indonesia and over northern Australia passed over western Indonesia 4-9 days prior to being measured. In these air masses the mixing ratios of ozone precursors, except for short-lived species, were similar to those over western Indonesia. In contrast, the ozone mixing ratio was higher by about 10 ppbv than that over Indonesia, indicating that photochemical production of ozone occurred during transport from Indonesia. The average rate of ozone increase (1.8 ppbv/d) during this transport is similar to the net ozone formation rate calculated by the photochemical model. This study shows that active convection over Indonesia carried polluted air upward from the surface and had a discernable influence on the distribution of ozone in the upper troposphere over the Indian Ocean, northern Australia, and the south subtropical Pacific Ocean, combined with NO production by lightning.
... Data in the tropical region of Asia, especially southeast Asia, one of the regions where the largest future changes of tropospheric O are expected (Brasseur et al., 1998), are still very limited. The multi-year tropospheric O measurements, mostly by ozone soundings, have been reported in Indonesia (Komala et al., 1996;Fujiwara et al., 2000) and Hong Kong (Chan et al., 1998(Chan et al., , 2000Liu et al., 1999). This literature addresses the in#uence of southeast Asian biomass burning on the enhancement of tropospheric ozone in this region. ...
... In addition, the lower tropospheric column is vertically well mixed. From ozone sonde data in Indonesia, the nearly constant O mixing ratios of 20}30 ppb have been found throughout the troposphere in the wet season (Komala et al., 1996;Fujiwara et al., 2000). The constant and almost identical O mixing ratios at Inthanon (at both elevations) and Srinakarin imply the homogenous mixing of the lower atmosphere. ...
The mixing ratios of surface ozone at two rural/remote sites in Thailand, Inthanon and Srinakarin, have been measured continuously for the first time. Almost identical seasonal variations of O3 with dry season maximum and a wet season minimum with a large seasonal amplitude are observed at both sites during 1996–1998. At Inthanon, the monthly averaged O3 mixing ratios range 9–55 ppb, with the annual average of 27 ppb. The ozone mixing ratios at Srinakarin are in the similar range, 9–45 ppb with annual average of 28 ppb. Based on trajectory analysis of O3 data at Inthanon, the long-range transport of O3 under Asian monsoon regime could primarily explain the low O3 mixing ratios of 13 ppb in clean marine air mass from Indian Ocean during wet season but only partly explain the relatively low O3 mixing ratios, 26 ppb or less, in continental air mass from northeast Asia either in wet or dry season. The highest O3 mixing ratios are found in air masses transported within southeast Asia, averaged 46 ppb in dry season. The high O3 mixing ratios during the dry season are suggested to be significantly due to the local/sub-regional scale O3 production triggered by biomass burning in southeast Asia rather than long-range transport effect.
... Leung et al., (2007) show that varying injection altitudes of biomass burning emissions resulted in increases in ozone further above the PBL and greater transport of NOx to remote regions. Comparing to our study, ozonesondes at Watukosek record lower tropospheric 400 ozone concentrations greater than 60 nmol mol -1 during biomass burning season (Adedeji et al., 2020;Komala et al., 1996), which is similar to the ozone concentrations predicted by UKESM1 but larger than the measurement station (10 -20 nmol mol -1 ) (Fig. 5f). However, there are many other uncertainties associated with biomass burning such as emission factors of both NOx and organic compounds (Schultz et al., 2008), and subsequent chemistry (Young et al., 2018) (Weber et al., 2023). ...
Surface ozone monitoring sites in the tropics are limited, despite the risk that surface ozone poses to human health, tropical forest, and crop productivity. Atmospheric chemistry models allow us to assess ozone exposure in unmonitored locations and evaluate the potential influence of changing policies and climate on air quality, human health, and ecosystem integrity. Here, we utilise in situ ozone measurements from ground-based stations in the pan-tropics to evaluate ozone from the UK Earth system model, UKESM1, with a focus on remote sites. The study includes ozone data from areas with limited previous data, notably Tropical South America, central Africa, and tropical North Australia. Evaluating UKESM1 against observations beginning in 1987 onwards, we show that UKESM1 is able to capture changes in surface ozone concentration at different temporal resolutions, albeit with a systematic high bias of 18.1 nmol mol-1 on average. We use the Diurnal Ozone Range (DOR) as a metric for evaluation and find that UKESM1 captures the observed DOR (mean bias of 2.7 nmol mol-1 and RMSE of 7.1 nmol mol-1) and the trend in DOR with location and season. Results from this study demonstrate the applicability of hourly output from UKESM1 for human and ecosystem health-based impact assessments, increase confidence in model projections, and highlight areas that would benefit from further observations. Indeed, hourly surface ozone data has been crucial to this study, and we encourage other modelling groups to include hourly surface ozone output as a default.
... They include meteor wind radar (Tsuda et al. 1995), wind profilers (Schafer et al. 2003), an X-band radar (Oigawa et al. 2017), and the Equatorial Atmosphere Radar. In 1992, LAPAN conducted a big-balloon launch, similar to that for cryogenic air sampling, and began successive ozonesonde observations at the Watukosek Observatory in Java (Komala et al. 1996 Additional Ozonesondes network (Thompson et al. 2003). From these experiences emerged the idea of attempting a synthesized CAS-SOWER campaign in Indonesia in collaboration with LAPAN in January 2013. ...
The stratospheric response to climate forcing, such as an increase in greenhouse gases, is often unpredictable because of interactions between radiation, dynamics, and chemistry. Climate models are unsuccessful in simulating the realistic distribution of stratospheric water vapor. The long-term trend of the stratospheric age of air (AoA), a measure that characterizes the stratospheric turnover time, remains inconsistent between diagnoses in climate models and estimates from tracer observations. For these reasons, observations designed specifically to distinguish the effects of individual contributing processes are required. Here, we report on the Coordinated Upper-Troposphere-to-Stratosphere Balloon Experiment in Biak (CUBE/Biak), an observation campaign organized in Indonesia. Being inside the “tropical pipe” makes it possible to study the dehydration in the tropical tropopause layer and the gradual ascent in the stratosphere while minimizing the effects of multiple circulation pathways and wave mixing. Cryogenic sampling of minor constituents and major isotopes was conducted simultaneously with radiosonde observations of water vapor, ozone, aerosols, and cloud particles. The water vapor “tape recorder,” gravitational separation, and isotopocules are being studied in conjunction with tracers that are accumulated in the atmosphere as dynamical and chemical measures of elapsed time since stratospheric air entry. The observational estimates concerning the AoA and water vapor tape recorder are compared with those derived from trajectory calculations.
... Oltmans et al. (2001) with ozonesondes were attributable to the transport of air masses affected by biomass burning in Australia and South America. In Indonesia, during the local late dry season 5 between September and November, enhancements of tropospheric O 3 concentrations are often observed (Komala et al., 1996;Fujiwara et al., 2000), and similar O 3 enhancements have also been observed in Malaysia between March and May (Yonemura et al., 2002a). Especially during El Niño periods, when severe droughts and extensive biomass burning occurred in Indonesia, remarkably large O 3 increases have persisted 10 (Fujiwara et al., 1999;Yonemura et al., 2002b). ...
Occurrence of ozone (O3)-enhanced layers in the troposphere over the equatorial Pacific Ocean and their seasonal variation were investigated based on ozonesonde data obtained at three Southern Hemisphere ADditional OZonesondes (SHADOZ) sites, Watukosek, American Samoa and San Cristobal, for 6 years between 1998 and 2003. O3-enhanced layers were found in about 50% of observed O3 profiles at the three sites on yearly average. The formation processes of O3-enhanced layers were investigated by meteorological analyses including backward trajectories. On numerous occasions, O3-enhanced layers resulted from the transport of air masses affected by biomass burning. The contribution of this process was about 30% at San Cristobal during the periods from February to March and from August to September, while it was relatively low, about 10%, at Watukosek and Samoa. A significant number of the O3-enhanced layers were attributed to the transport of midlatitude upper-troposphere and lower-stratosphere (UT/LS) air. Meteorological analyses indicated that these layers originated from equatorward and downward transport of the midlatitude UT/LS air masses through a narrow region between high- and low-pressure systems around the subtropical jet stream. This process accounted for more than 40% at Watukosek between May and December, about 60% or more at Samoa all year around, and about 40% at San Cristobal between November and March, indicating that it was important for O3 budget over the equatorial Pacific Ocean.
... 4). Such an O 3 maximum was indicated in previous observations (e.g., Komala, 1996;Ziemke et al., 2009). We in- vestigate here the origin of this O 3 maximum and its interannual variability by interpret- ing the satellite observations using a global three-dimensional (3-D) chemical transport 15 model (CTM). ...
We examine the distribution of tropical tropospheric ozone (O<sub>3</sub>) from the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES) by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem). MLS and TES observations of tropospheric O<sub>3</sub> during 2005 to 2009 reveal a distinct, persistent O<sub>3</sub> maximum, both in mixing ratio and tropospheric column, in May over the Equatorial Southern Indian Ocean (ESIO). The maximum is most pronounced in 2006 and 2008 and less evident in the other three years. This feature is also consistent with the total column O<sub>3</sub> observations from the Ozone Mapping Instrument (OMI) and the Atmospheric Infrared Sounder (AIRS). Model results reproduce the observed May O<sub>3</sub> maximum and the associated interannual variability. The origin of the maximum reflects a complex interplay of chemical and dynamic factors. The O<sub>3</sub> maximum is dominated by the O<sub>3</sub> production driven by lightning nitrogen oxides (NO<sub>x</sub>) emissions, which accounts for 62% of the tropospheric column O<sub>3</sub> in May 2006. We find the contribution from biomass burning, soil, anthropogenic and biogenic sources to the O<sub>3</sub> maximum are rather small. The O<sub>3</sub> productions in the lightning outflow from Central Africa and South America both peak in May and are directly responsible for the O<sub>3</sub> maximum over the western ESIO. The lightning outflow from Equatorial Asia dominates over the eastern ESIO. The interannual variability of the O<sub>3</sub> maximum is driven largely by the anomalous anti-cyclones over the southern Indian Ocean in May of 2006 and 2008. The lightning outflow from Central Africa and South America is effectively entrained by the anti-cyclones followed by northward transport to the ESIO.
... During September-October, tropospheric column ozone may exceed 50 DU over Africa, South America, and the tropical Atlantic, compared to ~30 DU in April or May (Logan and Kirchhoff 1986;Thompson et al. 1996). Ozone pollution from African fires frequently crosses the Indian and Pacific Oceans, where it has been detected in soundings over La Réunion (Baldy et al. 1996), Java, Indonesia (Komala et al. 1996);Tahiti;French Polynesia;Samoa;and Fiji (Oltmans et al. 2001). ...
This article describes the Southern Hemisphere Additional Ozonesondes (SHADOZ) network of ozonesonde radiosonde stations in the southern Tropics and subtropics. SHADOZ was initiated in 1998 by NASA, NOAA, and a team of international meteorological services and space agencies to remedy a paucity of ozone profile data in a region of intense natural variability and anthropogenic change. SHADOZ augments launches at selected sites and provides a public archive of ozonesonde and radiosonde data (see additional information online at croc.gsfc.nasa.gov/shadoz). Ozone is important because of its role as an atmospheric UV shield, surface pollutant, oxidant, and greenhouse gas. Ozone profile data are essential for the detection of ozone trends and for verification of satellite ozone retrievals. Instrumentation, data, and a summary of the first scientific findings from SHADOZ are presented. A zonal view shows that troposphere ozone accumulates over the south tropical Atlantic and adjacent continents throughout the year, consistent with large-scale atmospheric motion. At individual stations, week-to-week variations in tropospheric ozone profiles reflect episodic meteorology, for example, convection or advected pollution.
... [16] Monthly variations in TTO (surface to 16 km) and integrated ozone within 2-km layers are depicted in Figures 2 and 3, respectively. A spring maximum in TTO is evident and confirms the well-established Southern Hemisphere seasonal trend observed at many stations, for example, Natal in Brazil (5.9°S, 35.2°W) [Kirchhoff et al., 1991], Brazzaville in the Congo (4°S, 15°E) [Cros et al., 1992;Nganga et al., 1996;Diab et al., 1996a;Thompson et al., 1996], Ascension Island (8°S, 14°W) [Cros et al., 1992;Diab et al., 1996a], Reunion Island (21°S, 55°E) [Baldy et al., 1996;Taupin et al., 1999], and Watukosek in Indonesia (7.5°S, 112.6°E) [Komala et al., 1996;Fujiwara et al., 1998Fujiwara et al., , 1999Fujiwara et al., , 2000. The spring maximum has been variously attributed to photochemical sources such as biomass burning, biogenic emissions, and lightning production, as well as to stratospheric injection of ozone-rich air, or some combination of the above. ...
Ozonesonde measurements over Irene in South Africa are reported for the period 1990 to 1994 and a more recent period, 1998 to 2002, when the station became part of the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. Irene displays the characteristic Southern Hemisphere springtime tropospheric ozone maximum, but its seasonal features are modulated by both tropical and midlatitude influences because of its location (25°54'S, 28°13'E) on the boundary of zonally defined meteorological regimes. The tropical savanna biomass burning signature, namely, the spring maximum, is less distinct in the lower troposphere than at stations closer to biomass burning source regions nearer the equator, although long-range transport and recirculation in the subtropical anticyclonic gyre over southern Africa permit the buildup of relatively high springtime midtropospheric ozone. Midlatitude dynamical influences are evident, predominantly in winter when upper tropospheric ozone is enhanced as a result of stratospheric-tropospheric injection of ozone. Mean tropospheric ozone values range between 40 and 60 ppbv throughout the year and increase by ~20 ppbv in spring. The increase (~10 ppbv) in surface and lower tropospheric ozone between the two time periods is attributed to an increase in urban-industrial emissions. A classification of ozone profiles using a cluster analysis has enabled the delineation of a background and ``most polluted'' profile. Enhancements of at least 30% occur throughout the troposphere in spring, and in certain layers, increases close to 100% are observed.
... Although tropical Asia is a region of extensive biomass burning (Hao and Liu, 1994;Molingreu et al., 1996;Jones, 1997), there are only very limited reports of ozone enhancements associated with this burning. What reports there are have been for Indonesia (Komala et al., 1996;Folkins et al., 1997) and New Guinea (Kim and Newchurch, 1998). As far as we know this is the first attempt to link observations of enhanced ozone amounts with biomass burning over continental Southeast Asia (Burma, Thailand, Laos, Cambodia, and Vietnam). ...
Ozone peaks with mixing ratios as high as 138ppbv were observed in the lower troposphere (2.5–4.5km) over Hong Kong in spring. Simultaneously observed high humidity suggests that this enhanced ozone was not the result of transport from the upper troposphere. Back trajectory analysis suggests that these enhancements resulted from lateral transport. Air masses arriving at the altitude of the ozone peaks appear to have passed over continental Southeast Asia where the bulk of biomass burning occurs at this time of the year (February–April). We hypothesize that biomass burning in this region provided the necessary precursors for the observed ozone enhancement. As far as we know this is the first observation of highly enhanced ozone layers associated with biomass burning in continental Southeast Asia.
... These high CO levels suggest the possibility of biomassburning-induced tropospheric ozone over the western Pacific Ocean. reported marginally elevated tropospheric ozone over the western Pacific Ocean in October 1992 from the analysis of TOMS data. azonesonde analysis over Watukosek, Indonesia (7.5øS, 112.6øE), [Komala et al., 1996] suggests that the enhancement of ozone mixing ratios in the lower and middle troposphere in September and October 1993 may be linked to biomass burning. However, the seasonal variation of tropospheric ozone over the western Pacific Ocean remains unsolved because of a lack of long-term comprehensive measurements. ...
Using NIMBUS-7 version-7 Total Ozone Mapping Spectrometer (TOMS) ozone-column measurements, we derive lower-tropospheric ozone amounts over western South America and over the western Pacific Ocean near New Guinea from the column difference between two nearby regions with a topographic contrast, mountain and sea level. The seasonal variation of lower tropospheric-column ozone from ozonesondes at Natal, Brazil, agrees well with the seasonal variation of lower-tropospheric ozone over areas east and west of the Andes at the Natal latitude. This result suggests that, in the presence of the persistent easterly winds throughout the year over equatorial South America, favorable conditions exist for transporting biomass-burning products from burning regions to western South America. The seasonal variation of lower-tropospheric ozone over New Guinea shows a distinguishable annual cycle with a maximum in July-September and a minimum in January-February. Because the ozone monthly variation is well anticorrelated with monthly rainfall (the maximum ozone episode occurs during the dry season), biomass burning appears to be a likely precursor of the elevated ozone in a mechanism similar to the mechanism observed over South America and Africa. Overall, we observed less lower-tropospheric ozone over western New Guinea (6.6+/-2.2 Dobson units (DU) annual mean and monthly extrema) than over the plains east of the Andes (9.0+3.4/-2.0DU.) The tropospheric-ozone linear trend derived from a regression of the deseasonalized monthly averaged lower-tropospheric ozone amount versus time east of New Guinea (upwind of the biomass-burning areas) shows no significant trend; however, west of New Guinea (downwind of the biomass burning regions) we find a statistically significant increase of 0.06+/-0.04 [DU yr-1] (95% confidence interval (c.i.)), corresponding to 1.0+/-0.6 [% yr-1] (95% c.i.). The magnitude of this increasing trend is similar to the magnitude of the trend in the lower-troposphere ozone in western South America.
... Ozonesonde soundings and total ozone measurement with the Brewer spectrophotometer have been conducted at Watukosek ð7:51S; 112:61EÞ; Indonesia since 1992 and since 1993, respectively (Komala et al., 1996;Fujiwara et al., 2000). These ozone observations have revealed the seasonal and interannual variabilities of tropospheric ozone in this region. ...
Ozonesonde observation campaigns were conducted over the Indonesian maritime continent in September-October 1998 and in August-September 1999. Three stations were used for each campaign, Watukosek ð7:51S; 112:61EÞ; Kototabang ð0:201S; 100:31EÞ; and Pontianak ð0:031N; 109:31EÞ for the 1998 campaign, and Watukosek, Kototabang, and Darwin ð12:251S; 130:551EÞ for the 1999 campaign. Both periods were basicallycharacterized as the La Ni * na period, and the tropospheric ozone concentrations showed normal values. Temporal variation and horizontal distribution of an ozone layered structure with a 1-1.5-km thickness were obtained just below the tropopause at the two equatorial stations during the 1998 campaign. Meteorological data analyses including the reverse domain filling technique suggested that the most plausible explanation for the layer is the quasi-horizontal, thin intrusion from the northern midlatitude lower stratosphere associated with a breaking Rossbywave and large-scale flow pattern. r 2002 Elsevier Science Ltd. All rights reserved.
... During September–October, tropospheric column ozone may exceed 50 DU over Africa, South America, and the tropical Atlantic, compared to ~30 DU in April or May (Logan and Kirchhoff 1986; Thompson et al. 1996). Ozone pollution from African fires frequently crosses the Indian and Pacific Oceans, where it has been detected in soundings over La Réunion (Baldy et al. 1996), Java, Indonesia (Komala et al. 1996);Tahiti; French Polynesia; Samoa; and Fiji (Oltmans et al. 2001). In contrast to the Atlantic, tropospheric ozone column amounts over the tropical Pacific were usually less than 30 DU (Komhyr et al. 1989; Fishman et al. 1991 ), although one equatorial cruise found a number of soundings with a tropospheric column depth < 10 DU (Kley et al. 1996). ...
1] Daily ozone soundings taken from the R/V Ronald H. Brown from 7 July through 11 August 2004 as part of the Intercontinental Chemical Transport Experiment (INTEX) Ozonesonde Network Study (IONS) are used to investigate the vertical structure of ozone over the Gulf of Maine and to characterize variability in sources of tropospheric ozone: stratosphere, regional convection and lightning, advection, and local boundary layer pollution. These soundings were part of a network of twelve IONS (http://croc.gsfc.nasa.gov/intex/ions.html) stations that launched ozonesonde-radiosonde packages over the United States and maritime Canada during the INTEX/ International Consortium for Atmospheric Research on Transport and Transformation (ICARTT)/New England Air Quality Study (NEAQS) project from 1 July to 15 August 2004. Four of the IONS stations were in mid-Atlantic and northeast United States; four were in southeastern Canada. Although the INTEX/ICARTT goal was to examine pollution influences under stable high-pressure systems, northeastern North America (NENA) during IONS was dominated by weak frontal systems that mixed aged pollution and stratospheric ozone with ozone from more recent pollution and lightning. These sources are quantified to give tropospheric ozone budgets for individual soundings that are consistent with tracers and meteorological analyses. On average, for NENA stations in July-August 2004, tropospheric ozone was composed of the following: 10–15% each local boundary layer and regional sources (the latter including that due to lightning-derived NO) and 20–25% stratospheric ozone, with the balance ($50%) a mixture of recently advected ozone and aged air of indeterminate origin.
... In addition to the formation of ground level ozone from the precursors there is a possibility of intrusion of ozonerich stratospheric and upper tropospheric air that can Fig. S2, Supplementary information showing high ozone concentration at the altitude of around 5 km, which suggests possibility of the downward transport of O 3 when strong convective motion exists (Ninong and Slamet, 1995). This is an interesting a subject of further study especially for the near equator location of Jakarta. ...
Surface O3 air quality in Jakarta, Indonesia, was analyzed using hourly monitoring data during January 2002–March 2004 from the five automatic monitoring stations with the aim to provide the first insight into the ozone formation and accumulation leading to the high ozone levels over the city. The city location near the equator with the intensive emission sources is of especial interest in this regard. The surface O3 levels in Jakarta were high which frequently exceeded the hourly national ambient air quality standard (120 ppb), i.e. over 450 hourly measurements in 2002 and 2003 or 0.7% over 66,000 hourly ozone measurements at the five stations during 2002–2003. The monthly average of O3 was maximum in October and minimum in February. Selected days of episodic high O3 in April, May, and October, and low ozone days in February were comparatively analyzed in relation to local and synoptic meteorological conditions. The high ozone days were characterized by more intense solar radiation, higher temperature, and lighter surface wind which are favorable for photochemical production of O3. Low pressure gradients on synoptic charts of the high ozone days linked to the low wind and more stagnant air that are favorable for ozone build-up over the city. Further studies, including photochemical modeling, are required to understand better the conditions leading to high ozone in the city in order to formulate the ozone management strategies.
... Ozonesonde soundings and total ozone measurement with the Brewer spectrophotometer have been conducted at Watukosek ð7:51S; 112:61EÞ; Indonesia since 1992 and since 1993, respectively (Komala et al., 1996;Fujiwara et al., 2000). These ozone observations have revealed the seasonal and interannual variabilities of tropospheric ozone in this region. ...
Ozonesonde observation campaigns were conducted over the Indonesian maritime continent in September–October 1998 and in August–September 1999. Three stations were used for each campaign, Watukosek (7.5°S,112.6°E), Kototabang (0.20°S,100.3°E), and Pontianak (0.03°N,109.3°E) for the 1998 campaign, and Watukosek, Kototabang, and Darwin (12.25°S,130.55°E) for the 1999 campaign. Both periods were basically characterized as the La Niña period, and the tropospheric ozone concentrations showed normal values. Temporal variation and horizontal distribution of an ozone layered structure with a 1–1.5-km thickness were obtained just below the tropopause at the two equatorial stations during the 1998 campaign. Meteorological data analyses including the reverse domain filling technique suggested that the most plausible explanation for the layer is the quasi-horizontal, thin intrusion from the northern midlatitude lower stratosphere associated with a breaking Rossby wave and large-scale flow pattern.
... ozone increased over Borneo Island in March}April 1983. Kim and Newchurch (1998) also showed that tropospheric ozone deduced from the TOMS data increased in the west of New Guinea in September}October 1982. In the 1990s, ground-based observations were initiated in Indonesia and detected increases of tropospheric ozone over the Indonesian re- gion. Komala et al. (1996) reported that tropospheric ozone observed at Watukosek (7.63S, 112.63E), Indonesia , increased in September}October 1993. In 1994 and 1997, extensive forest "res occurred in Indonesia again. Analyses of satellite infrared image data and the TOMS aerosol index (e.g. Hsu et al., 1996) indicated that the "res occurred in south Sumatra Isla ...
Significant increases of total ozone were observed both by the total ozone mapping spectrometer (TOMS) and by the Brewer spectrophotometer in Indonesia in September and October of 1994 and 1997, during the El Niño periods, when extensive forest fires were reported in Sumatra Island, Kalimantan (the southern part of Borneo Island) and south New Guinea. The two observations were consistent with each other, and the total ozone increases were attributed to the tropospheric ozone increases because their amplitudes agreed with those of integrated tropospheric ozone increases derived from ozonesonde observations. The TOMS data indicated that the horizontal distributions and temporal variations of the ozone increases were similar in both years; the ozone increases were found mainly over Sumatra Island and the Malay Peninsula in September, and spread out from Kalimantan to the central Indian Ocean in October. This ozone distribution was partly different from the reported fire areas. This difference suggested the importance of the horizontal advection due to the easterly wind in the lower troposphere and of the vertical transport due to the upward wind at the west of Sumatra Island, in the ozone maximum area. Distinctive total ozone increases similar to those in 1994 and 1997 repeatedly appeared over the Indonesian region in the TOMS data between 1979 and 1998. The average ozone increase in this region was estimated by subtracting the background structure of total ozone in the tropics, and this analysis showed that large ozone increases mostly occurred in the dry season during the El Niño periods when the precipitation decreased significantly and extensive forest fires occurred frequently in Indonesia.
... At stations with little pollution ozone (Nairobi, for example, under normal conditions ), total and stratospheric ozone show similar seasonal differences. The impact of seasonal transport of midtropospheric ozone from biomass burning has been documented at Natal [Logan and Kirchhoff, 1986; Kirchhoff et al., 1991 Kirchhoff et al., , 1996, Ascension [Fishman et al., 1992; Olson et al., 1996; Thompson et al., 1996b], Watukosek [Komala et al., 1996; Fujiwara et al., 1999 Fujiwara et al., , 2000 and Réunion [Baldy et al., 1996; Taupin et al., 1999]. More remote from source regions are the Pacific sites, where persistent high-ozone layers introduced by biomass burning have been described by Newell et al. [1999] and Oltmans et al. [2001]. ...
A network of 10 southern hemisphere tropical and subtropical stations, designated the Southern Hemisphere Additional Ozonesondes (SHADOZ) project and established from operational sites, provided over 1000 ozone profiles during the period 1998-2000. Balloon-borne electrochemical concentration cell (ECC) ozonesondes, combined with standard radiosondes for pressure, temperature, and relative humidity measurements, collected profiles in the troposphere and lower to midstratosphere at: Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; and Natal, Brazil. The archived data are available at: <http://croc.gsfc.nasa.gov/shadoz>. In this paper, uncertainties and accuracies within the SHADOZ ozone data set are evaluated by analyzing: (1) imprecisions in profiles and in methods of extrapolating ozone above balloon burst; (2) comparisons of column-integrated total ozone from sondes with total ozone from the Earth-Probe/Total Ozone Mapping Spectrometer ( TOMS) satellite and ground-based instruments; and (3) possible biases from station to station due to variations in ozonesonde characteristics. The key results are the following: (1) Ozonesonde precision is 5%. (2) Integrated total ozone column amounts from the sondes are usually to within 5% of independent measurements from ground-based instruments at five SHADOZ sites and overpass measurements from the TOMS satellite (version 7 data). (3) Systematic variations in TOMS-sonde offsets and in ground-based-sonde offsets from station to station reflect biases in sonde technique as well as in satellite retrieval. Discrepancies are present in both stratospheric and tropospheric ozone. (4) There is evidence for a zonal wave-one pattern in total and tropospheric ozone, but not in stratospheric ozone Pages: art. no. 8238
... Almost all model CO was attributable to Indonesian biomass burning (Figure 7). Second, ozonesonde data was collected at Watukosek (7.6°S, 112.6°E) on the island of Java, which lies south of the major burning areas on Borneo and Sumatra [Komala et al., 1996; Fujiwara et al., 2000]. The data were collected by the Earth Observation Research Center (EORC)/National Space Development Agency of Japan (NASDA) and are available from their data archive (http://www.eorc.nasda.go.jp/AtmChem/GLACE/indonesia/ index.html).Figure 8 shows the vertical profile of measured O 3 above the station compared with model O 3 . ...
The Indonesian wildfires of 1997 released large amounts of trace gases and aerosols (e.g., $\sim$ 130 Tg of carbon monoxide (CO)) from September to November. Using the GEOS-CHEM model of tropospheric chemistry and transport, we conducted a study of this burning event, including sensitivity simulations, to estimate the impacts of the trace gas and aerosol emissions on tropospheric chemistry. The emissions from the fires were estimated using the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) data product and fire-count data from the Along Track Scanning Radiometer (ATSR) World Fire Atlas as surrogates for biomass burning. The model captures most of the daily variations of CO and ozone (${O}_{3}$) observed in the region affected by the pollution. Export of the pollution from the Indonesian region was primarily in the prevailing easterlies in the free troposphere to the tropical Indian Ocean where the bulk of the pollution lay between 20°N to 20°S from September to November. The model’s tropospheric CO and O3 columns were elevated by more than 50% and 10%, respectively, over the tropical Indian Ocean in a simulation with emissions from the fires relative to a simulation without the emissions. Another important export pathway was to the tropical and subtropical South Pacific Ocean in the southern subtropical jet. A more episodic pathway occurred to the tropics and subtropics of the North Pacific Ocean. By December, the tropospheric CO column from the fires had mixed zonally and somewhat symmetrically about the equator impacting both the Northern and Southern Hemisphere similarly. The model’s CO column was elevated by 10–20% from 30°N to 45°S in December, by 5–10% poleward of 45°S, and by less than 5% poleward of 45°N. The relative impact of the fires was lower in the Northern Hemisphere, as the background CO column is typically higher there. The fires decreased the concentration of the hydroxyl radical (OH) in the model by more than 20% over much of the tropical Indian Ocean through consumption by CO, heterogeneous loss of odd-oxygen radicals (${HO}_{x}$) on black (BC) and organic carbon (OC) aerosols, and reduction of UV light by the aerosols. The net direct, shortwave radiative forcing at the top of the atmosphere of OC and BC aerosols from the fires was relatively small, as their forcings were similar, but of opposite signs. The net forcing at the surface, however, was large, about -10 W ${m}^{-2}$ over most of the tropical Indian Ocean and as low as -150 W ${m}^{-2} over the burning regions in ${O}_{3}$ Indonesia, indicating that aerosols from the fires significantly perturbed the tropical radiative budget. The calculated forcing of ${O}_{3}$ was minor relative to those of BC and OC aerosols.
... Oltmans et al. (2001) suggested that the O 3 -enhanced layers observed at Fiji (18.1 @BULLET S, 178.2 @BULLET E), Samoa (14.3 @BULLET S, 189.4 @BULLET E), Tahiti (18.0 @BULLET S, 211.0 @BULLET E), and Galapagos (0.9 @BULLET S, 270.4 @BULLET E) with ozonesondes were attributable to the transport of air masses affected by biomass burning in Australia and South America. In Indonesia, during the local late dry season 5 between September and November, enhancements of tropospheric O 3 concentrations are often observed (Komala et al., 1996; Fujiwara et al., 2000 ), and similar O 3 enhancements have also been observed in Malaysia between March and May (Yonemura et al., 2002a). Especially during El NiñoNi˜Niño periods, when severe droughts and extensive biomass burning occurred in Indonesia, remarkably large O 3 increases have persisted 10Fujiwara et al., 1999; Yonemura et al., 2002b). ...
Occurrence of ozone (O<sub>3</sub>)-enhanced layers in the troposphere over the equatorial Pacific Ocean and their seasonal variation were investigated based on ozonesonde data obtained at three Southern Hemisphere ADditional OZonesondes (SHADOZ) sites, Watukosek, American Samoa and San Cristobal, for 6 years between 1998 and 2003. O<sub>3</sub>-enhanced layers were found in about 50% of observed O<sub>3</sub> profiles at the three sites on yearly average. The formation processes of O<sub>3</sub>-enhanced layers were investigated by meteorological analyses including backward trajectories. On numerous occasions, O<sub>3</sub>-enhanced layers resulted from the transport of air masses affected by biomass burning. The contribution of this process was about 30% at San Cristobal during the periods from February to March and from August to September, while it was relatively low, about 10%, at Watukosek and Samoa. A significant number of the O<sub>3</sub>-enhanced layers were attributed to the transport of midlatitude upper-troposphere and lower-stratosphere (UT/LS) air. Meteorological analyses indicated that these layers originated from equatorward and downward transport of the midlatitude UT/LS air masses through a narrow region between high- and low-pressure systems around the subtropical jet stream. This process accounted for more than 40% at Watukosek between May and December, about 60% or more at Samoa all year around, and about 40% at San Cristobal between November and March, indicating that it was important for O<sub>3</sub> budget over the equatorial Pacific Ocean.
Jakarta Greater Area (JGA) has encountered recurrent challenges of air pollution, notably, high ozone levels. We investigate the trends of surface ozone (O3) changes from the air quality monitoring stations and resolve the contribution of meteorological drivers in urban Jakarta (2010–2019) and rural Bogor sites (2017–2019) using stepwise Multi Linear Regression. During 10 years of measurement, 41% of 1-h O3 concentrations exceeded Indonesia’ s national threshold in Jakarta. In Bogor, 0.1% surpassed the threshold during 3 years of available data records. The monthly average of maximum daily 8-h average (MDA8) O3 anomalies exhibited a downward trend at Jakarta sites while increasing at the rural site of Bogor. Meteorological and anthropogenic drivers contribute 30% and 70%, respectively, to the interannual O3 anomalies in Jakarta. Ozone formation sensitivity with satellite demonstrates that a slight decrease in NO2 and an increase in HCHO contributed to declining O3 in Jakarta with 10 years average of HCHO to NO2 ratio (FNR) of 3.7. Conversely, O3 increases in rural areas with a higher FNR of 4.4, likely due to the contribution from the natural emission of O3 precursors and the influence of meteorological factors that magnify the concentration.
Tropospheric ozone in the tropics zone is significant in terms of the oxidizing efficiency and greenhouse effect. However, in the upper troposphere, the ozone budget in the tropics has not been fully understood yet because of the sparsity of the range-resolved observations of vertical ozone concentration profiles. A DIAL (differential absorption lidar) system for vertical ozone profiles have been installed in the equatorial tropopause region over Kototabang, Indonesia (100.3E, 0.2S). We have observed large ozone enhancement in the upper troposphere, altitude of 13 - 17 km, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause at equatorial region.
Problem statement: Variations of ozone (O 3) concentrations in the Eastern Coastal Region of the Malaysia peninsula were investigated using data obtained from the Malaysian Department of the Environment. The aim of this study was to determine the monthly and seasonal variations of ozone concentrations at all monitoring sites. This study deals with the air quality data recorded at four air quality monitoring stations in the East Coast of the Malaysian peninsula over a ten year period (1997- 2006). Approach: We focused on the usage of S-Plus and SPSS to analyze this data. The S-Plus programming was used to impute missing data and SPSS was used to obtain the variations of ozone and also to clarify the relationship between stations. Results: Over the entire 10 year period (1997- 2006), the trend in annual baseline ozone generally increased each year for all the four monitoring sites. There was also a seasonal variability in the measured ozone levels with high concentrations during the southwest monsoon and the northeast monsoon season, producing a significant increase in the amplitude of the seasonal cycle. The results also shown that the highest ozone concentrations were recorded at the Bukit Kuang air monitoring station (S1), with a daily mean value of 19 ppb followed by the Indera Mahkota air monitoring station (S2). The concentration of ozone recorded at Kota Bharu (S3) and Kuala Terengganu (S4), two stations located in the city centre, was found to be lower than the values recorded at Bukit Kuang and Indera Mahkota. The correlation between O 3 and NO is high at Kuala Terengganu (S4) (ρ = -0.579), whilst the relationship between O 3 and NO 2 are high (ρ = -0.397) at Indera Mahkota (S2). Conclusion: The concentration of ozone in the East Coast of Malaysian peninsula depends on the concentration of NOx and seasonal meteorological factors.
We present the climatology of tropospheric ozone over Peninsular Malaysia in tropical Asia for the 8 years from 1992 through 1999 as measured by ozonesondes twice a month. The mean ozone concentrations in vertical profile were in the same range (30–40 ppbv) as those observed at Watukosek, Indonesia, and were lower than those at Natal, Brazil, South America, and at Brazzaville, Congo, Africa, indicating that air masses over Peninsular Malaysia are primarily influenced by the maritime environment and deep convection, as shown by the significant levels of water vapor in the middle troposphere throughout the year. Seasonally averaged ozone concentrations were highest in December, January, and February (DJF) from 6 to 7.5 km altitude and in March, April, and May (MAM) at all other heights and were lowest in June, July, and August (JJA) and September, October, and November (SON), excluding 1994 and 1997, at all heights. The ozone enhancements during DJF in the middle troposphere could be caused by depression of the deep convection because of the positive temperature anomaly and negative water vapor anomaly. The ozone enhancements above the middle troposphere (>5 km) in MAM, especially in 1997 and 1998, could be predominantly attributed to photochemical production from enhanced ozone precursor gases of Northern Hemisphere origin, especially biomass burning in continental Southeast Asia. Large ozone enhancements as high as 10–20 Dobson units observed during SON of 1994 and 1997 were associated with large-scale biomass burnings in Indonesia.
Pronounced enhancements of total and tropospheric ozone were observed with the Brewer spectrophotometer and ozonesondes at Watukosek (7.5°S, 112.6°E), Indonesia in 1994 and in 1997 when extensive forest fires were reported in Indonesia. The integrated tropospheric ozone increased from 20 DU to 40 DU in October 1994 and to 55 DU in October 1997. On October 13, 1994, most ozone mixing ratios were more than 50 ppbv throughout the troposphere and exceeded 80 ppbv at some altitudes. On October 22, 1997, the concentrations were more than 50 ppbv throughout the troposphere and exceeded 100 ppbv at several altitudes. The coincidences of the ozone enhancements with the forest fires suggest the photochemical production of tropospheric ozone due to its precursors emitted from the fires for both cases. The years of 1994 and 1997 correspond to El Niño events when convective activity becomes low in Indonesia. Thus, in this region, it is likely that pronounced enhancements of tropospheric ozone associated with extensive forest fires due to sparse precipitation may take place with a period of a few years coinciding with El Niño events. This is in a marked contrast to the situation in South America and Africa where large-scale biomass burnings occur every year.
Regular ozonesonde observation and total ozone observation with the Brewer spectrophotometer have been conducted at Watukosek (7.5°S, 112.6°E), Indonesia, since 1993. Three seasons are recognized for the vertical distribution of tropospheric ozone. (1) During the local wet season, between December and March, the ozone mixing ratio is nearly constant at 25 ppbv throughout the troposphere. (2) During the transition season from wet to dry, between April and July, the mixing ratio is often enhanced in the uppermost troposphere. (3) During the local dry season, between August and November, the concentration is enhanced in the planetary boundary layer, and extensive forest fires in Indonesia associated with the strong El Niño events of 1994 and of 1997 have enhanced the ozone mixing ratio in the middle troposphere, the integrated tropospheric ozone, and the total ozone at Watukosek.
An intensive observation with ozonesondes and rawinsondes was conducted in Indonesia in May and June 1995 to investigate a phenomenon of ozone enhancement in the tropical upper troposphere. We obtained the characteristics of an enhancement that continued for about 20 days, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause and the Madden-Julian oscillation (MJO) in the troposphere. The isoline of ozone mixing ratio of 40 nmol/mol moved by 5.0 km downward from 17.8 km to 12.8 km, while the tropopause height was 16.2-17.8 km throughout the period. Moreover, the maximum ozone concentration of 300 nmol/mol at the tropopause was concurrent with the maximum eastward wind phase of the Kelvin wave. The detailed mechanism of the ozone transport is interpreted as follows: The downward motion associated with the Kelvin wave and the MJO transported the stratospheric ozone into the troposphere, and the air mixing due to the Kelvin wave breaking at the tropopause also caused stratosphere-troposphere exchange. The upper limit of the net amount of ozone transported from the stratosphere was estimated to be 9.9 Dobson units with the zonal and meridional extents of the ozone-increased region of more than 6.6×106m and 1.8×106m, respectively, to imply the potential to affect the photochemistry around the tropical tropopause.
There was extensive biomass burning in Indonesia, northern Australia, and New Guinea during September and October 1994. This paper discusses two accidental encounters of biomass plumes from the 1994 Airborne Southern Hemisphere Ozone Experiment and Measurements for Assessing the Effects of Stratospheric Aircraft campaign (ASHOE/MAESA). During the October 23 descent into Fiji, and an ascent from Fiji on October 24, the NASA ER-2 passed through layers highly enhanced in NO, NOy, CO, and O3. These layers occurred near an altitude of 15 km. Back trajectories and satellite images indicate that the layers probably originated as outflow from a convective disturbance near New Guinea. The measurements indicate that deep convection can inject emissions from southeast Asian biomass burning to near tropical tropopause altitudes. Deep convection magnifies the impact of biomass burning on tropospheric chemistry because of the much longer residence times and chemical lifetimes of species in the upper tropical troposphere. Transport of the products of southeast Asian biomass burning into the upper tropical troposphere, followed by southward high-level outflow and advection by the subtropical jet, may play a significant role in dispersing these emissions on a global scale. Anthropogenic emissions from countries in southeast Asia are likely to increase in the future as these countries become more highly industrialized. This transport mechanism may play a role in increasing the impact of these types of emissions as well.
Using Total Ozone Mapping Spectrometer (TOMS) version-7 level-2
clear-sky (reflectivity ≤ 20%) ozone measurements corrected for
aerosol effects and sea-glint errors, we derived Lower Tropospheric
Ozone (LTO) west and east of the Andes, the Mexican and Rocky Mountains,
the mountains in Africa and the Arabian Peninsula, New Guinea, and the
Himalayan Mountains. The derived results agree reasonably well with the
seasonality of LTO from ozonesonde observations at Boulder, Cristobal,
Fiji, Java, and Tahiti. The LTO seasonality found in the biomass burning
seasons characterized by the ATSR World Fire Atlas west and east of the
Andes (23°S-2°N), east of the Mexican Mountains
(15°-23°N), South Sudan (6°-14°N), South Africa
(30°-28°S), and west of New Guinea is consistent with the
influence of biomass burning on the formation of tropospheric ozone in
these regions. The significant El Niño influence on LTO west of
New Guinea is evident throughout several El Niño cycles. The
spring maximum in ozone west of the Mexican Mountains, in western China,
and west of the Andes (32°-23°S) is consistent with a
stratospheric intrusion source. East of the Mexican Mountains
(23°-30°N), both west and east of the Rocky Mountains, in north
Sudan and Iraq, and in western China, high concentrations of ozone are
found in these continental and coastal regions which are affected by
anthropogenic sources. The maximum ozone in these regions usually occurs
in the summer due to photochemical ozone production. A summer LTO
minimum occurs in coastal regions west of the Andes and west of Mexico,
due to ozone destruction in low NOx and high H2O
marine environment. A summer minimum also occurs in south Sudan in the
rainy season. The LTO in the northern tropics of South America
(4°-10°N), Africa (1°S-2°N), and east of New Guinea
(7°-3°S) experiences little seasonal variation.
In situ and laser remote measurements of gases and aerosols were made
with airborne instrumentation to establish a baseline chemical signature
of the atmosphere above the South Pacific Ocean during the NASA Global
Tropospheric Experiment (GTE)/Pacific Exploratory Mission-Tropics A
(PEM-Tropics A) conducted in August-October 1996. This paper discusses
general characteristics of the air masses encountered during this
experiment using an airborne lidar system for measurements of the
large-scale variations in ozone (O3) and aerosol
distributions across the troposphere, calculated potential vorticity
(PV) from the European Centre for Medium-Range Weather Forecasting
(ECMWF), and in situ measurements for comprehensive air mass
composition. Between 8°S and 52°S, biomass burning plumes
containing elevated levels of O3, over 100 ppbv, were
frequently encountered by the aircraft at altitudes ranging from 2 to 9
km. Air with elevated O3 was also observed remotely up to the
tropopause, and these air masses were observed to have no enhanced
aerosol loading. Frequently, these air masses had some enhanced PV
associated with them, but not enough to explain the observed
O3 levels. A relationship between PV and O3 was
developed from cases of clearly defined O3 from stratospheric
origin, and this relationship was used to estimate the stratospheric
contribution to the air masses containing elevated O3 in the
troposphere. The frequency of observation of the different air mass
types and their average chemical composition is discussed in this paper.
I present an analysis of ozonesonde data, synthesizing what is known
about the distribution of tropospheric ozone. Major features of the
distribution are highlighted, and recommendations are given for testing
three-dimensional models of tropospheric chemistry and transport with
these data. The data are analyzed on pressure surfaces and relative to
the height of the thermal tropopause. A minimum of 20 soundings are
required for 95% confidence intervals of the ozone monthly means to be
less than ±30% near the extratropical tropopause. Twenty
soundings also ensures means reliable to better than ±15% for
800-500 hPa for the extratropics and for 800-100 hPa in the tropics.
Ozone variability is higher in the upper troposphere for subtropical
locations than for tropical locations, and 35 soundings are required for
400-100 hPa for the means to be defined to better than ±15%. For
northern middle and high latitudes, the broad summer maximum in ozone in
the middle troposphere extends all the way up to the tropopause. Median
concentrations at the tropopause are highest in June and July, typically
125-200 ppb, and are a factor of 2 smaller in winter. Highest values of
ozone are in spring 2 km above the tropopause. The change in the phase
of the annual cycle of ozone between the tropopause and the region
immediately above it, and the steep concentration gradients across the
tropopause, suggest that high vertical resolution (˜1 km) will be
required in models to simulate this behavior. Mean ozone values in the
middle troposphere are approximately constant from 30° to 75° in
the winter in both hemispheres, while there is a maximum from 35° to
50°N in summer. In the northern subtropics, there is a summer
minimum in middle tropospheric ozone over the Pacific and a summer
maximum over the Atlantic which appear to be related to differences in
circulation. Mean ozone values over Samoa are similar to those measured
20-30 years ago over Panama. Ozone is higher over the tropical South
Atlantic (Natal) than over the western Pacific (Samoa) all year from
about 800 hPa to the tropopause; ozone is most similar in May and June
over the Atlantic and Pacific, the months with minimum burning in the
tropics. The ozone maximum at Samoa in the middle and upper troposphere
in October is caused by long-range transport of ozone and its precursors
from biomass burning, with the peak lagging that at Natal by about a
month. The secondary peak in ozone in January and December at South
Atlantic sites reflects transport of biomass burning effluents from the
Northern Hemisphere. The sonde data were used in combination with
surface and satellite data to derive a gridded climatology for
tropospheric ozone.
We examine the distribution of tropical tropo-spheric ozone (O3) from the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES) by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem). MLS and TES observations of tro-pospheric O3 during 2005 to 2009 reveal a distinct, persistent O3 maximum, both in mixing ratio and tropospheric column, in May over the Equatorial Southern Indian Ocean (ESIO). The maximum is most pronounced in 2006 and 2008 and less evident in the other three years. This feature is also consis-tent with the total column O3 observations from the Ozone Mapping Instrument (OMI) and the Atmospheric Infrared Sounder (AIRS). Model results reproduce the observed May O3 maximum and the associated interannual variability. The origin of the maximum reflects a complex interplay of chem-ical and dynamic factors. The O3 maximum is dominated by the O3 production driven by lightning nitrogen oxides (NOx) emissions, which accounts for 62% of the tropospheric col-umn O3 in May 2006. We find the contribution from biomass burning, soil, anthropogenic and biogenic sources to the O3 maximum are rather small. The O3 productions in the light-ning outflow from Central Africa and South America both peak in May and are directly responsible for the O3 max-imum over the western ESIO. The lightning outflow from Equatorial Asia dominates over the eastern ESIO. The inter-annual variability of the O3 maximum is driven largely by the anomalous anti-cyclones over the southern Indian Ocean in May 2006 and 2008. The lightning outflow from Central Africa and South America is effectively entrained by the anti-cyclones followed by northward transport to the ESIO.
We examine seasonal and geographical distributions of tropospheric ozone production and mixing ratios over East Asia with a global three-dimensional chemical transport model called Model of Ozone and Related Tracers, version 1 (MOZART 1). Net ozone production within the East Asian boundary layer exhibits three distinct seasonal cycles depending on region (north of 20°N, 5-20°N and south of 5°N). North of 20°N, net ozone production over East Asia from spring through autumn is found to have a maximum extending from 25°N-40°N and from central eastern China to Japan, resulting from the strong emission and transport of anthropogenic O3 precursors. In winter, maximum O3 production in this region occurs between 20°N and 30°N. This is a region of long-range transport. Over the Indochina peninsula, between 5°N and 20°N, net O3 production is controlled by the seasonal cycle between wet and dry seasons and has a maximum at the end of the dry season due to emissions from biomass burning. South of 5°N, in the true tropics, O3 mixing ratios are relatively constant throughout the year and do not exhibit a seasonal cycle. A spring-summer maximum of net O3 production is found throughout the troposphere in East Asia. We estimate an annual net O3 production in East Asia of 117 Tg/yr. Both model results and analysis of measurements of O3/CO correlations over East Asia and Japan show strong variability as a function of both photochemical activity and seasonal meteorology, and indicate ozone export off the coast of East Asia in spring. An upper estimate of O3 export from East Asia to the Pacific Ocean in the mid-1980s of 3.3 Gmol/d (58 Tg/yr) is obtained.
Vertical ozone profiles over Singapore (lat 1°20′N, long 103°53′E) have been monitored by ozonesondes twice a month since August 1996. We report the vertical ozone profiles over Singapore from August 1996 to the end of 1999. During this time, large ozone enhancements occurred during three periods: March–June 1997, September–November 1997, and February–May 1998. These ozone enhancements were larger over Singapore than over Malaysia. Backward trajectory analyses revealed that the enhancements during September–November 1997, and February–May 1998 were associated with biomass burning in Indonesia and Southeast Asia. Outside the three periods, ozone concentrations over Singapore differed from those over Malaysia by not more than 2.5% at altitudes of between 2.6 and 7.6 km and by not more than 12% at altitudes of between 1 and 13.5 km. The minimum ozone concentrations in the middle and the upper troposphere were about 20 ppbv and were observed when the wind was easterly from the Pacific Ocean. Ozone concentrations at the bottom of the troposphere were near zero when the wind was southerly to westerly (from the larger, more urbanized and industrialized part of Singapore and the Strait of Malacca), implying that ozone-destroying reactions were occurring with high concentrations of urban pollutants. We conclude that the ozone enhancements observed in the free troposphere resulted from the effects of extensive biomass burning combined with the modified circulation (suppressed convection of maritime air masses) that occurs during El Niño events.
this paper, we conduct simulations of September to December 1997 using the GEOS-CHEM global model of tropospheric chemistry and transport [Bey et al., 2001a] with the purpose of identifying the export pathways of trace gases and aerosols emitted from these fires and of quantifying the impacts of the pollution on the oxidizing capacity and radiative budget of the troposphere
Atmospheric flow patterns are examined over the South Atlantic Ocean where a maximum of tropospheric ozone has been observed just west of southern Africa. We investigate the flow climatology during October and perform a case study for 6 days during October 1989. Analyses from the European Center for Medium-Range Weather Forecasting are employed, and a high-resolution global spectral model is used to prepare forecasts during the period. Horizontal and vertical motions are examined and used to prepare three-dimensional backward trajectories from the region of greatest ozone. An initially zonally symmetric distribution of ozone is treated as a passive tracer and advected by three-dimensional flows forecast by the global model. Results from the passive tracer simulation indicate that three-dimensional advection alone can produce a maximum of tropospheric ozone in the observed location. In addition, the trajectories suggest that by-products of biomass burning could be transported to the area of maximum ozone. Low-level flow from commonly observed regions of burning in Africa streams westward to the area of interest. Over Brazil, if the burning by-products are carried into the upper troposphere by convective process, they then could be transported eastward to the ozone feature in approximately 5 days. There is considerable subsidence over the tropical southern Atlantic, such that stratospheric influences also are a factor in producing the ozone maximum. Both planetary-scale and transient synoptic-scale circulation features play major roles in the various transport processes that influence the region. In summary, the observed tropospheric ozone maximum appears to be caused by a complex set of horizontal and vertical advections, transport from regions of biomass burning, and stratospheric influences.
A device is described that is suitable for use in measuring the vertical distribution of atmospheric ozone up to 30 km. The method is based on the principle of detecting the reaction of ozone with a neutral buffered halide solution coulometrically, wherein free halogen is liberated. It consists of a platinum gauze cathode and an active carbon anode which are immersed in the solution. When the air containing ozone is drawn into the reaction cell at a constant rate, the electrical current dependent on the ozone amount aspirated flows through the output circuit between the two electrodes. The resulting current is impressed on an amplifier, whose output varies with the magnitude of the input current. Data telemetry is accomplished by periodic connection of the sensor to the radiosonde transmitter. The error in the measured value is estimated to be within ±2%, provided that the shift in background current is corrected, judging from the comparison of the vertically integrated ozone amount with the total amount of ozone measured by the Dobson's spectrometer method. This device is simple in construction, low in cost, easy to handle and stable in operation.Several successful flight re s ults are discussed from the standpoint of instrumentation.
An aircraft measurement program was undertaken in the savanna regions of
central South America in the dry season of 1980 to investigate the
atmospheric effects of large-scale biomass burning. The smoke from the
fires was found to be largely confined within an approximately 3-km-deep
boundary layer capped by a subsidence inversion or a stable layer. This
condition typically persists for week-long periods as a result of the
synoptic subsidence occurring during the dry season. Photochemical
production of ozone occurred in the polluted layer over the entire
Cerrado region of central Brazil. The factors controlling the
concentration of this ozone are examined, and an estimate of the amount
of ozone produced is reported.
A numerical study of the tropospheric ozone budget is conducted by using a one-dimensional model which takes into account both diffusion and photochemical processes. It is shown that if ozone is treated as an inert species in the troposphere, large vertical eddy diffusion coefficients and an ozone flux from the stratosphere must be used to reproduce the observed tropospheric ozone profiles in the northern hemisphere mid-latitudes during the summer. Furthermore, consideration of the reactions which destroy ozone in the troposphere would lead to the destruction of about half of the ozone injected in the troposphere. Thus it is likely that there are also reactions which produce ozone in the troposphere. The possibility that methane oxidation reactions are responsible for this production is examined. It is shown that a model which includes both the aforementioned photochemistry and prescribed physical processes can reproduce the observations reasonably; however, the uncertainty of certain reaction rate constants and the lack of understanding of the tropospheric odd nitrogen budget prohibit the quantification of the tropospheric ozone budget. The model results also suggest that the time scales of both the physical and photochemical processes are both of the order of 1-3 months.
The potential importance of deforestation and biomass burning for the atmospheric CO2 cycle has received much attention and caused some controversy. Biomass burning can contribute extensively to the budgets of several gases which are important in atmospheric chemistry. In several cases the emission is comparable to the technological source. Most burning takes place in the tropics in the dry season and is caused by man’s activities. The potential importance of deforestation and biomass burning for the atmospheric CO2 cycle has received much attention and caused some controversy. In this article we will show the probable importance of biomass burning as a trace gas source, which is caused by man’s activities in the tropics. We used the results of our global biomass burning analysis to derive some rough estimates of the sources of the important atmospheric trace gases CO, H2, CH4, N2O, NOx (NO and NO2), COS and CH3Cl from the worldwide burning of biomass.
The structures of the mean winds in the troposphere and lower stratosphere seemed to be affected by the Australian monsoon and the quasi-biennial oscillation, respectively. Frequency spectra indicated that the equatorial waves as well as the diurnal tides were dominant below about 25 km, while gravity waves with periods shorter than 4 days became more significant above 25 km. A 7-day oscillation showing an antiphase relation between the eastward and northward components and exhibiting large amplitudes was observed in the lower troposphere. The time-height variations of the activity of this 7-day oscillation were clearly correlated with a region of high relative humidity. -Authors
Field measurement programs in Brazil during the dry seasons in August and September 1979 and 1980 have demonstrated the large importance of the continental tropics in global air chemistry. Many important trace gases are produced in large amounts over the continents. During the dry season, much biomass burning takes place, especially in the cerrado regions, leading to a substantial emission of air pollutants, such as CO, NO
x
, N2O, CH4 and other hydrocarbons. Ozone concentrations are enhanced due to photochemical reactions. The large biogenic organic emissions from tropical forests play an important role in the photochemistry of the atmosphere and explain why CO is present in such high concentrations in the boundary layer of the tropical forest. Carbon monoxide production may represent more than 3% of the net primary productivity of the tropical forests. Ozone concentrations in the boundary layer of the tropical forests indicate strong removal processes. Due to atmospheric supply of NO
x
by lightning, there is probably a large production of O3 in the free troposphere over the Amazon tropical forests. This is transported to the marine-free troposphere and to the forest boundary layer.
Several field expeditions were organized in recent years to study modifications introduced into the lower atmosphere of the Amazon region, as a result of anthropogenic influence. In a simplified way, the legal Brazilian Amazon is formed by the rainforest ecosystem in the North and west, and the savanna (cerrado) in the central region. The frontier region between these two quite different types of vegetation is where most burning occurs, and due to the large areas and amounts of phytomass involved these burnings may represent sources of Global importance. This report describes enhancements of atmospheric ozone concentrations in the remote cerrado troposphere which are believed to result from biomass burning activity. The measurements were obtained in two field expeditions to the Brazilian cerrado region of central Brazil, an area subject to cyclic burning, during the local dry season. Ozone concentrations are known to increase in the burning season. However, this process is normally a gradual increase over the season and proportional at all heights. Occasionally, large layer enhancements are seen. Three such cases are discussed, showing concentrations of ozone between 80 and 120 ppbv (parts per billion by volume), when normal averages are about 60 ppbv. To our knowledge this is the first time that such large concentrations were observed in areas of biomass burning. In one event the ozone mixing ratio was increased in a layer near 800 mbar (2.0 km above ground) to a maximum of 112 ppbv, when the known maximum observed near this height was 80 ppbv. Other events show a layer near 250 mbar (10.9 km above ground) reaching 120 and 122 ppbv at the peak. It is believed that these are special events which could be produced by a coincidence of chemical production and dynamical layering effects.
A large ozone-profile data set has been obtained through balloon ozonesonde soundings at Natal, Brazil, during 1978-1988. Maximum ozone concentrations occur during local spring (September-October), and minimum concentrations during late autumn (April-May); the seasonal variation is much larger in the troposphere than in the stratosphere. If there were no seasonal variation in the stratosphere, the seasonal variation observed in the troposphere alone would be sufficient to drive a total ozone column variation of about 5 percent. This is about half the size of the variation observed in the Natal Dobson spectrophotometer data.
An analysis of more than 22,000 ozone profiles from Stratospheric Aerosol and Gas Experiment I (SAGE I) (1979-1981) and SAGE II (1984-1987) between 50 deg N and 50 deg S is used in conjunction with 9 years (1979-1987) of daily global depictions of total ozone from the TOMS instrument aboard Nimbus 7 to investigate the spatial distribution and seasonal cycle of the integrated amount of ozone in the troposphere. In the tropics, highest concentrations are found in the eastern Atlantic Ocean downwind (west) of Africa and maximize during the time when biomass burning is most prevalent, between July and October. A different seasonal cycle in the tropics is also observed over Indonesia, where a relative maximum is present in the March-April time frame, likewise consistent with when biomass burning is most prevalent. At mid-latitudes, highest concentrations are found downwind of Asia and maximize in the summer. Relatively higher amounts of tropospheric ozone are similarly observed downwind of North America and Europe. At mid-latitudes, the ratio between the amount of tropospheric ozone in the Northern Hemisphere and the amount in the Southern Hemisphere is 1.4, in good agreement with in situ measurements.
Airborne measurements of trace gas and aerosol species were obtained in the lower troposphere (less than 5 km) over the western Atlantic Ocean between 13 deg S and 40 deg N during the August/September 1990 NASA Chemical Instrument Test and Evaluation (CITE 3) experiment. The largest background O3 mixing ratios, averaging 35 and 70 ppbv within the mixed layer (ML) and free troposphere (FT; altitudes greater than 2.4 km), respectively, were found over the tropical South Atlantic. Several competing processes were observed to regulate O3 budgets in this region. Within the ML, rapid photochemical destruction produced a diurnal O3 variation of 8 ppbv and an O3/altitude gradient between the surface and 5 km of almost 10 ppbv (O3)/km. ML O3 concentrations were replenished by atmospheric downwelling which occurred at rates of up to and exceeding 1 cm/s. Ozone values within the subsiding FT air were enriched both by long-range transport of O3 produced photochemically within biomass combustion plumes and the downward propagation of dry, upper tropospheric air masses. Overall, the tropospheric O3 column below 3.3 km averaged 13.5 Dobson units (DU) over the South Atlantic region, which is 8-9 DU higher than observed during CITE 3 ferry flights over the northern tropical Atlantic Ocean or measured by ozonesondes over coastal Brazil during the wet season. An examination of simultaneous dew point and combustion tracer (e.g., CO) measurements suggests that the dry subsiding layers and biomass burning layers make approximately equal contributions to the observed O3 enhancement.
The algorithm used to correct total O3 from the total ozone mapping spectrometer (TOMS) for cloud effects is based on the measured reflectivity, a climatological cloud top height, and an assumed tropospheric O3 column amount below clouds. In regions of persistent subtropical marine stratocumulus it is assumed that this introduces a positive error into total O3 because these clouds are lower than the assumed mean cloud height used in the algorithm. This appears to be confirmed by high correlation between Nimbus 7 TOMS total O3 and reflectivity data for typical regimes of persistent stratus, as identified by the international satellite cloud climatology project (ISCCP) observations. The TOMS total O3 overestimate has been computed using Nimbus 7/solar backscattered ultraviolet total O3 derived using temperature humidity infrared radiometer (THIR) data for years 1979-1984. A functional relationship between the THIR/non-THIR total O3 difference and reflectivity is used with TOMS reflectivity to modify Nimbus 7 TOMS O3 data for selected regions and periods. The correction diminishes or eliminates a number of apparent O3 maxima, with reductions of up to 20 Dobson units (DU) in total O3 on daily maps and approximately 5 DU on monthly mean O3 maps. Significant correlation between corrected TOMS O3 and reflectivity data remains because low-altitude O3 is retrieved more efficiently over a high-albedo surface. It is also possible that dynamical influences leading to stratocumulus formation bring O3-enriched air into the area. These results imply that although good arguments can be made for the use of TOMS total O3 as a proxy for tropospheric O3 in the tropics, caution must be exercised in the use of daily and even monthly O3 maps in the vicinity of clouds. Further research into the TOMS algorithm in cloudy regions is required to derive reliable estimates of tropospheric O3.
During all eight flights conducted over the equatorial and tropical South Atlantic in the course of the Chemical Instrumentation Test and Evaluation (CITE 3) experiment, we observed haze layers with elevated concentrations of aerosols, O3, CO, and other trace gases related to biomass burning emissions. They occurred at altitudes between 1000 and 5200 m and were usually only some 100-300 m thick. These layers extended horizontally over several 100 km and were marked by the presence of visible brownish haze. Air mass trajectories indicate that these layers originate in the biomass burning regions of Africa and South America and typically have aged at least 10 days since the time of emission. In the haze layers, O3 and CO concentrations up to 90 and 210 ppb were observed, respectively. The two species were highly correlated. The ratio concentrations in plume minus background concentrations of O3/CO is typically in the range 0.2-0.7, much higher than the ratios in the less aged plumes investigated previously in Amazonia. In most cases, aerosol (0.12-3 micrometer diameter) number concentrations were also elevated by up to 400/cu cm in the layers; aerosol enrichments were also strongly correlated with elevated CO levels. Clear correlations between CO and NO(x) enrichments were not apparent due to the age of the plumes, in which most NO(x) would have already reacted away within 1-2 days. Only in some of the plumes could clear correlations between NO(y) and CO be identified; the absence of a general correlation between NO(y) and CO may be due to instrumental limitations and to variable sinks for NO(y). The average enrichment of the ratio concentrations in plume minus background concentrations of NO(y)/CO was quite high, consistent with the efficient production of ozone observed in the plumes. The chemical characteristics of the haze layers, together with remote sensing information and trajectory calculations, suggest that fire emissions (in Africa and/or South America) are the primary source of the haze layer components.
In the present analysis of tropospheric ozone data, attention is given to spatial and temporal variations. Two modes of seasonal behavior are noted for surface ozone at mid-latitudes: a broad summer maximum within a few hundred km of industrial/urban areas in Europe and the U.S., and a minimum in summer or autumn in sparcely populated regions that are remote from industrial activity. These and limited historical data indicate that summertime concentrations of ozone near the surface in the rural areas of Europe and the U.S. may have increased between 20 and 100 percent since the 1940s. It is suggested that the summer maximum in ozone and other observed trends are due to photochemical production associated with anthropogenic emissions of NO(x), hydrocarbons, and CO from fossil fuel combustion.
Carbon monoxide (CO) and ozone (O3) concentrations have been observed in the Brazilian Amazon region, at a site strongly affected by biomass burning (Cuiaba, 16 deg S, 58 deg W). Time variations are described for the first long-term program of studying the effect of biomass burning on O3 and CO over a complete seasonal cycle, including the seasonal maxima of 1987 and 1988. In order to obtain elements for comparison, an identical observational program was maintained at a site totally outside of the direct influence of biomass burning (Natal, 6 deg S, 35 deg W). The biomass burning contribution to the Cuiaba concentrations of CO and O3 is very large. Diurnal maxima concentrations exceeded 90 ppbv O3 in 1987 and 120 ppbv O3 in 1988, in September. For the wet season, the monthly average ozone concentration in March-April is about 10 ppbv. During the month of maxima, September, the O3 concentration average was 41 ppbv for 1987 and 71 ppbv for 1988. The CO concentrations are about 90 ppbv in the wet season. In September, 460 ppbv and 660 ppbv of CO were observed for 1987 and 1988, respectively. At Natal the seasonal variation is of the order of a factor of 2. During the wet season, the concentrations of CO and O3 at both stations are about the same.
An analysis of ozone measurements from Natal, Brazil (6 deg S, 35 W), with a focus on the seasonal behavior in the troposphere, is presented. The amplitude of seasonal cycle at Natal is much larger than at Panama (9 deg N), the only other tropical site for which similar data are available. Concentrations of ozone in the middle troposphere in the southern spring are unexpectedly high, 60-70 ppb, similar to values found at northern midlatitudes in summer, and larger by 20-30 ppb than values found at Panama and at southern midlatitudes. It is suggested that photochemical production of ozone associated with emissions of CO, hydrocarbons, and NO(x) from biomass burning may contribute significantly to the high values of ozone, but note that stratospheric intrusions could also play a role. The data available at present do not permit a definitive evaluation of the relative importance of these two sources of ozone. The data from Natal, in combination with recent aircraft and surface data, show that tropical ozone exhibits strong spatial and temporal inhomogeneities. The distribution of tropospheric ozone appears to be considerably more complex than the traditional view, which suggested a northern midlatitude maximum and north/-south hemispheric asymmetry. The seasonal cycle in the total column of ozone at Natal appears to mirror the behavior of the tropospheric contribution to the ozone column rather than the stratospheric contribution, and this may account for differences in the annual cycle of the total column at Natal versus other tropical locations.
The chemistry and dynamics of a convective system observed on February 2, 1987 in the EMEX and STEP campaigns are analyzed. Chemical and thermodynamic profiles in undisturbed air near the EMEX 9 system indicate that the troposphere was well mixed by previous convection. As a consequence there was little direct transport from the boundary layer to the upper troposphere and air transported upward was detrained throughout the middle and upper troposphere. There was minimal effect on O3 production. Other convective complexes located 800-900 km upstream produced greater perturbations on trace gas profile immediately below the tropopause. Ozone production was reduced by about 0.25 ppbv/d at these altitudes, representing a reduction in P(O3) of 15-20 percent over the column from 14.5 to 17 km. P(O3) from 12 to 17 km in a region distant from active convection and subject to lightning was 2-3 times higher than it would have been without lightning.
An analysis of 33 ozonesonde launches in Brazzaville, Congo (4 deg S, 15 deg E), between June 1990 and May 1991 is presented. The data indicate highest tropospheric amounts between June and early October, coincident with the dry season and with the presence of enhanced widespread biomass burning. The seasonal cycle of ozone derived from the ozonesonde measurements is in good agreement with the climatological seasonal cycle inferred from the use of satellite data amd both seasonal cycles peak in September. Averaged throughout the year, the integrated amount of ozone derived from the ozonesondes is 44 Dobson units (DU) and is 39 DU using the satellite data. Within the troposphere the highest partial pressures are generally found at pressure levels near 700 mbar (about 3 km). Using simultaneous ozonesonde data from Ascension Island (8 deg S, 15 deg W), examples are presented illustrating that differences in the troposphere are primarily responsible for the observed spatial gradients of total ozone observed by TOMS.
Distribution of tropospheric ozone determined from satel-lite data Time variation and of CO and 03 concentration in a region subject to biomass burning
- J Fishman
- C E Watson
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- J Logan
Fishman J., Watson C. E., Larsen J. C. and Logan J. (1990) Distribution of tropospheric ozone determined from satel-lite data. J. geophys. Res. 95, 3599 3617. Kirchhoff V. W. J. H. and Rasmussen R. A. (1990) Time variation and of CO and 03 concentration in a region subject to biomass burning. J. geophys. Res. 95, 7521-7532.
Effect of marine stratocumulus on TOMS ozone Radiosonde observations of equato-rial atmosphere dynamics over Indonesia, 1. Equatorial waves and diurnal tides
- A M Thompson
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Thompson A. M., McNamara D. P., Pickering K. E. and McPeters R. D. (1993) Effect of marine stratocumulus on TOMS ozone. J. geophys. Res. 98, 23,051-23,057. Tsuda T., Murayama Y., Wiryosumarto H., Hariyono S. W. B. and Kato S. (1994) Radiosonde observations of equato-rial atmosphere dynamics over Indonesia, 1. Equatorial waves and diurnal tides. J. geophys. Res. 99, 10,491-10,505.
Diurnal variation of tropospheric ozone in Indonesia. In Ozone Depletion Im-plication for the Tropics
- N Komala
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Komala N. and Ogawa T. (1991) Diurnal variation of tropospheric ozone in Indonesia. In Ozone Depletion Im-plication for the Tropics (edited by Ilyas M.), pp. 178-188.
Diurnal and seasonal variations of the tropospheric ozone in tropical Asia), pp. 437-440. A. Deepak Publishing Co Surface Ozone Data at Watukosek and Bandung Upper tropospheric ozone produc-tion following mesoscale convection during STEP/ EMEX
- T Ogawa
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- A M Thompson
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- T L Kucsera
Ogawa T. and Komala N. (1989) Diurnal and seasonal variations of the tropospheric ozone in tropical Asia. In Ozone in the Atmosphere (edited by Bojkov R. D. and Fabian P.), pp. 437-440. A. Deepak Publishing Co. Ogawa T. and Komala N. (1990) Surface Ozone Data at Watukosek and Bandung, Vol. 1, Dec. 198(~Dec. 1988. Geophys. Res. Lab., Univ. Tokyo and Atmos. Res. and Develop. Center~LAPAN. Pickering K. E., Thompson A. M., Wei-Kuo Tao and Kucsera T. L. (1993) Upper tropospheric ozone produc-tion following mesoscale convection during STEP/ EMEX. J. geophys. Res. 98, 8737-8749.
The meteorological environment of the tropospheric ozone maximum over the tropical south At-lantic ocean Tropospheric ozone: seasonal behavior, trends, and anthropogenic influence
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Diurnal variation of tropospheric ozone in Indonesia
- Komala