Fig 1 - uploaded by Patrick Chazette
Content may be subject to copyright.
Source publication
We present measurements of the vertical structure of the aerosol backscattering coefficient in the lower troposphere, which have been performed at the city of Thessaloniki in N. Greece, during the years 1996 and 1997. A ground-based backscatter lidar system operated throughout the year, mostly around local noon hours. The lidar measurements were ac...
Context in source publication
Context 1
... city of Thessaloniki (40.53N}22.93E) and the surrounding suburbs have close to one million inhabitants. As seen in Fig. 1, the city is developed along the Thermaikos Gulf and is northwest}southeast (NW}SE) orientated, with the sea-shore mainly on its southwest (SW). The industrial area of Thessaloniki is located at the west}northwestern (WNW) part of the city, and includes an oil re"nery complex and a chemical plant. The Laboratory of Atmospheric Physics, ...
Citations
... The results reveal that the average value of the LRs was 45.57 ± 17.48 for clean aerosol. The LR of BB/UI aerosol was 60.87 ± 12.18, close to the LR of 62 detected in Balis et al. (2000). Besides, the LR of DD and MX were 52.24 ± 14.30 and 47.06 ± 11.21, respectively. ...
The aerosol observations in Xi’an (34.25°N, 108.983°E), a typical urban site in Northwest China, were conducted using a sky-radiometer from January 2015 to March 2018. Multi-year variations of aerosol optical properties (AOPs) and lidar ratios (LRs) were simultaneously analyzed and calculated. In particular, LRs in 340 nm were compared and validated using the UV-Raman lidar (RL) measurements. During the study period, aerosol optical depth at 500 nm (AOD500) had significant seasonal variation, with a maximum value of 0.68 in winter and a minimum value of 0.59 in autumn. Ångström exponent (AE) exhibited different seasonal variation patterns, and the minimum (0.81) and maximum (1.06) values appeared in spring and summer, respectively. The spectral difference between AE400–675 and AE675–870 indicated that high AOD675 values (>1.0) were affected by accidental factors (e.g., dust weather in spring and winter) and the accumulation of fine particle aerosols across all seasons. The relationship between AOD500 and AE400–870 was used to distinguish different aerosol types. Overall, mixed aerosols (MX) accounted for the largest contribution (ranging from 40.14% in autumn to 69.9% in spring), followed by biomass-burning or urban/industrial aerosols (BB/UI) (with the smallest value of 19.9% in spring, and the largest value of 43.66% in winter). Single-scattering albedo (SSAs) experienced weak seasonal variation, with a minimum in winter and a maximum in spring. The seasonal aerosol volume size distributions (VSDs) generally exhibited the trimodal patterns. The particle radius (R) of less than 0.5 μm is considered as fine mode, the coarse mode is R greater than 2.5 μm, and the middle mode is located somewhere in between them. The real CRI were ∼1.41–1.43, with no significant difference among different seasons. Besides, the LRs derived by combining sky-radiometer with Mie-scattering theory changed greatly with weather from 49.95 ± 8.89 in summer to 63.95 ± 6.77 in autumn, which were validated by RL with the errors within a certain height range of less than 10%. We confirmed the feasibility of using the LR of UV band from sky-radiometer as a reference value for the Fernald or Klett method.
... Active remote sensing of tropospheric aerosols by lidar systems over the Mediterranean region has strongly developed in the past two decades for aerosol vertical profiling (e.g., Hamonou et al., 1999;Balis et al., 2000Balis et al., , 2004Balis et al., , 2006Gobbi et al., 2000;Sicard et al., 2002Sicard et al., , 2011Sicard et al., , 2012De Tomasi et al., 2003;Dulac & Chazette, 2003;Berthier et al., 2006;Mona et al., 2006;Papayannis et al., 2008a;Royer et al., 2010;Mamouri et al., 2013;Chazette et al., 2014Chazette et al., , 2016Chazette et al., , 2019aNisantzi et al., 2014Nisantzi et al., , 2015Flamant et al., 2015;Barragan et al., 2017;Mandija et al., 2017;Marinou et al., 2017;Ortiz-Amezcua et al., 2017;Ansmann et al., 2019;Benkhalifa et al., 2019;Fernandez et al., 2019;Chazette, 2020). Thanks to transportable systems, it is now a relatively common technique deployed during field campaigns either ground based (e.g., Chazette et al., 2014Chazette et al., , 2016Chazette et al., , 2019a or airborne Chazette, 2020). ...
In this chapter, we review the measured optical properties of different aerosol types observed in the Mediterranean region, from both ground-based and aircraft in situ measurements and from remote sensing. We focus our description on the most relevant optical parameters used in radiative forcing calculations, namely, the aerosol optical depth (AOD) and its spectral dependence (Angström exponent, AE), the single scattering albedo (SSA) and the asymmetry parameter (g). We also consider the aerosol backscatter to extinction ratio (BER), which is a key parameter in the inversion of lidar profiles for deriving the vertical distribution of the aerosol extinction.KeywordsAerosol optical depth (AOD)Angström exponentAerosol single scattering albedo (SSA)Absorption propertiesAsymmetry parameterAerosol extinction-to-backscatter ratio (BER)Lidar ratio (LR)Aerosol typesColumn averagesVertical profileAltitude dependenceSpatiotemporal variabilityLong-term averagesMediterranean basin averagesSpaceborne productsGround-based observationsShip-based observationsIn situ measurementsAirborne measurementsSun photometerAERONETLidarEARLINETMineral dustMarine aerosolContinental aerosolBiomass burning aerosol (BBA)Smoke particlesPollution particlesPolluted dustWavelengthSpectral dependenceShortwaveLongwaveUltravioletVisibleNear-infraredInfraredSurface observation inventoryFranceGreeceIsraelItalySpainTurkeyAlboran IslandCorsicaCreteLampedusaSardiniaSicilyWestern Mediterranean
... Conference Proceedings "Climate, atmosphere and water resources in the face of climate change" Sofia, 14 -15 October 2019 For all these reasons, the study of transport and transformation of aerosols in the troposphere, and in particular within the atmospheric boundary layer, has become a key issue for atmospheric chemistry, atmospheric turbulence studies and climate change modelling (Seibert et al., 2000;Haeffelin et al., 2012;Su et al., 2015). Air pollution levels and dispersion characteristics in mountainous areas are complex (Balis et al., 2000;Vijayakumar and Devara, 2013). Mountain ranges around valleys block or divert the prevailing winds, thereby altering the atmospheric thermal structure, which can create local winds and change the meteorology over short distances. ...
FIRST SCIENTIFIC CONFERENCE, DEDICATED TO THE 150-th ANNIVERSARY OF THE BULGARIAN ACADEMY OF SCIENCES, and THE 1-th ANNIVERSARY OF THE CLIMATE, ATMOSPHERE AND WATER RESEARCH INSTITUTE// CLIMATE, ATMOSPHERE AND WATER RESOURCES IN THE FACE OF CLIMATE CHANGE// BOOK OF PROCEEDINGS// БЪЛГАРСКА АКАДЕМИЯ НА НАУКИТЕ// ИНСТИТУТ ЗА ИЗСЛЕДВАНЕ НА КЛИМАТА, АТМОСФЕРАТА И ВОДИТЕ// ПЪРВА НАУЧНА КОНФЕРЕНЦИЯ ПОСВЕТЕНА НА 150-ТА ГОДИШНИНА НА БЪЛГАРСКАТА АКАДЕМИЯ НА НАУКИТЕ/ 1-ВАТА ГОДИШНИНА НА ИНСТИТУТА ЗА ИЗСЛЕДВАНЕ НА КЛИМАТА, АТМОСФЕРАТА И ВОДИТЕ// КЛИМАТ, АТМОСФЕРА И ВОДНИ РЕСУРСИ В УСЛОВИЯТА НА КЛИМАТИЧНИ ПРОМЕНИ// СБОРНИК ДОКЛАДИ//
... For all these reasons, the study of transport and transformation of aerosols in the troposphere, and in particular within the atmospheric boundary layer, has become a key issue for atmospheric chemistry, atmospheric turbulence studies and climate change modelling (Seibert et al., 2000;Haeffelin et al., 2012;Su et al., 2015). Air pollution levels and dispersion characteristics in mountainous areas are complex (Balis et al., 2000;Vijayakumar and Devara, 2013). Mountain ranges around valleys block or divert the prevailing winds, thereby altering the atmospheric thermal structure, which can create local winds and change the meteorology over short distances. ...
BULGARIAN ACADEMY OF SCIENCES
CLIMATE, ATMOSPHERE AND WATER RESEARCH INSTITUTE
FIRST SCIENTIFIC CONFERENCE
DEDICATED TO
THE 150-th ANNIVERSARY OF THE BULGARIAN ACADEMY OF SCIENCES
THE 1-th ANNIVERSARY OF THE CLIMATE, ATMOSPHERE AND WATER RESEARCH INSTITUTE
CLIMATE, ATMOSPHERE AND WATER RE-SOURCES IN THE FACE OF CLIMATE CHANGE
SOFIA, 14-15 OCTOBER 2019
BOOK OF PROCEEDINGS
Конференцията е посветена на 150-та годишнина на Българска академия на науките и 1-вата годишнина на Института за изследване на климата, атмосферата и водите със съдействие на Националната научна програма „Опазване на околната среда и намаляване на риска от неблагоприятни явления и природни бедствия“ 2019 – 2023, работни пакети:
РП.I.2. Воден баланс и водни ресурси на страната и
РП.I.3. Качество на националните водни ресурси (повърхностни и подземни).
Тематичните направления включват изследвания по:
⚫ Климатични промени и причиняващите ги естествени и антропогенни фактори
⚫ Физикохимични процеси в атмосферата
⚫ Водни ресурси и тяхното използване и опазване
⚫ Качество на повърхностните и подземни водни ресурси
⚫ Водни ресурси на територията на Югозападна България
Организатори:
Институт за изследвания на климата, атмосферата и водите (ИИКАВ) при БАН в парт-ньорство с:
-Геологически институт - БАН
-Глобално партньорство за водите - България
-Съюз по водно дело при ФНТД
Програмен съвет:
чл. кор. проф. дн Екатерина Бъчварова (ИИКАВ-БАН) - председател
проф. д-р Емил Бурназки (ИИКАВ-БАН)
проф. дн Явор Чапанов (ИИКАВ-БАН)
проф. дн Веселин Александров (ИИКАВ-БАН)
проф. д-р Алексей Бендерев (ГИ-БАН)
доц. д-р Татяна Орехова (ИИКАВ-БАН) – секретар
Редактори: Татяна Орехова, Явор Чапанов, Емил Бурназки
... All of these studies were preceded by early campaigns such as that of the European project Mediterranean Dust Ex- periment (e.g., Hamonou et al., 1999) or even networked ob- servations such as those of the lidar Earlinet network (e.g., Balis et al., 2000;Pappalardo et al., 2004;Papayannis et al., 2008;and more recently Granados-Muñoz et al., 2016). Coupling in situ measurements and modeling, the vertical structure of the planetary boundary layer under sea breeze conditions was also investigated during the ExperimentS to COnstrain Models of atmospheric Pollution and Trans- port of Emissions (ESCOMPTE; Cros et al., 2004) over the Marseille-Berre area, ∼ 40 km west of the French Riviera. ...
... This specific morphology facilitates the recirculation of air masses, and therefore aerosols, via the sea breeze-land breeze cycle, the alternation between the katabatic and anabatic winds, and the guiding of the air mass circulation in the valleys and along the seashore. Sea breeze is an effective means of exchange between the marine or continental boundary layer and the free tropo- sphere, especially around the Mediterranean basin (Bouchlaghem et al., 2007;Lasry et al., 2005;Levy et al., 2008;Millán et al., 1991). The aerosols trapped in the low and medium free troposphere will then be transported over long distances and may arrive over the Mediterranean coasts where they will reach the surface via free or forced convection processes gen- erated by the mountains. ...
For the first time, a 355 nm backscatter N2-Raman
lidar has been deployed on the western part of the French Riviera to
investigate the vertical aerosol structure in the troposphere. This lidar
system, based at the AERONET site of Toulon–La Garde, performed continuous
measurements from 24 June to 17 July 2014, within the framework of the
multidisciplinary program Mediterranean Integrated Studies at the Regional
and Local Scales (MISTRALS). By coupling these observations with those of
the spaceborne instruments Cloud-Aerosol LIdar with Orthogonal Polarization
(CALIOP), Spinning Enhanced Visible and InfraRed Imager (SEVIRI), and
Moderate Resolution Imaging Spectroradiometers (MODIS), the spatial extents
of the aerosol structures are investigated. The origins of the aerosol
plumes are determined using back trajectories computed by the Hybrid Single
Particle Lagrangian Integrated Trajectory (HYSPLIT). This synergy allowed us to
highlight plumes of particulate pollutants moving in the low and medium free
troposphere (up to ∼5 km above the mean sea level) towards
the French Riviera. This pollution originates from the Spanish coast,
more particularly from Costa Blanca (including Murcia) and Costa Brava–Costa
Daurada (including Barcelona). It is mainly due to traffic, but also to
petrochemical activities in these two regions. Desert aerosol plumes were
also sampled by the lidar. The sources of desert aerosols have been
identified as the Grand Erg Occidental and Grand Erg Oriental. During desert
dust events, we highlight significant differences in the optical
characteristics in terms of the backscatter-to-extinction ratio (BER, inverse
of the lidar ratio) between the planetary boundary layer, with 0.024 sr−1
(∼42 sr), and the free troposphere, with 0.031 sr−1 (∼32 sr). These differences are greatly reduced in
the case of pollution aerosol plume transport in the free troposphere (i.e.,
0.021 and 0.025 sr−1). Transported pollution aerosols appear to
have
similar BER to what is emitted locally. Moreover, using the correlation
matrix between lidar aerosol extinction profiles as a function of altitude,
we find that during transport events in the low free troposphere, aerosols
may be transferred into the planetary boundary layer. We also note that the
relative humidity, which is generally higher in the planetary boundary layer
(>80 %), is found to have no significant effect on the BER.
... The lidar technique allows, by using the aerosol as a tracer, to determine the heights of the different aerosol layers. Characteristics such as aerosol optical depth, water vapour content andÅngström coefficients related to the aerosols concentrations and size, and respectively, to the atmospheric pollution can be determined by sun photometers [8][9][10][11] ]. ...
The results obtained during five experimental campaigns in the period 2010-2014 are presented in this paper. Only summer data are discussed because of the highest aerosol optical depth (AOD) values during this period of the year, and optimally active and passive remote sensing are realized (clear sunny days). Investigations were carried out in three regions of the city of Sofia (Institute of Electronics, Astronomical Observatory at Borisova Gradina Park, and National Institute of Geophysics, Geodesy and Geography (NIGGG)). A ceilometer CHM-15K, two sun photometers Microtops II, and an automatic meteorological station were used during the experiments. The analysis of the aerosol backscattered signal obtained by the ceilometer reveals that the height of the mixing layer varied from 1500 to 2500 (3000) m above ground level. Two types of formation of the atmospheric boundary layer (ABL) were observed during the investigations – a rapidly increasing ABL and a gradually increasing ABL. The AOD in 2010 had the highest mean values 0.619 and 0.536 at wavelength 380 nm and 500 nm, respectively. The lowest AOD values 0.122 and 0.092 were observed at the same wavelengths in 2012. Water vapour content (WVC) values exhibited behaviour similar to the AOD one – the highest values were obtained in 2010, while the lowest ones – in 2012. Different types of AOD and WVC behaviour were observed. The influence of the atmospheric aerosol on the solar radiation distribution and, respectively, on the ABL development is considered and discussed.
... Aerosols also affect the abundance and distribution of atmospheric trace gases by heterogeneous chemical reactions and other multiphase processes [1], [2]. Aerosols originate from natural (sea salts, air-borne dust, volcanoes and storms) and anthropogenic sources (fossil fuels combustion, biomass burning and gas-to-particle conversion) [3], [4], . The spatial and temporal variation of the characteristics of the aerosols are large due to the production sources, transport and removal processes [5]. ...
The atmosphere over Penang Island is monitored for one year using a ground based Lidar. The Lidar signals are processed to obtain the AOD, extinction coefficients and the PBL heights to provide an overview of the atmospheric conditions in Penang. The data are averaged daily and plotted for the year of 2014. The AOD and extinction coefficients display seasonal trends that increase during the monsoon seasons (Southwest monsoon and Northeast monsoon) and decrease during the inter-monsoon seasons. During the monsoon seasons, a mixture of clear and hazy atmospheric conditions is found due to the presence of rain which removes the particulates or aerosols from the atmosphere. If no rain occurs, aerosols transported over Penang will stay in the atmosphere and be removed after a certain period. The average AOD is 0.4034 for year 2014 with a maximum of 1.0787 on a hazy day and a minimum of 0.0354 on a clear day. The extinction coefficient range is quite wide especially during the monsoonal months owing to the intervention of aerosol layers in the atmosphere of Penang. A clear day will have a smaller range of extinction coefficients. The planetary boundary layer has an average height of 0.878 km. Thicker PBLs are found after monsoon seasons as the aerosols has sunk to the earth surface from higher altitudes. The PBL has an opposing trend to the AOD and extinction coefficients. The atmosphere over Penang Island consists of a mixture of marine particles and fine particles that are mainly transported to Penang by the monsoon winds from the surrounding sea and biomass burnings in the neighboring SEA countries. An overview of the atmospheric conditions in Penang for a whole year is meaningful for further research.
... Saharan dust particle concentrations ≥ 50 μg/m 3 are found to be dangerous for the respiratory system of the humans. 1,2,3,5 Mineral aerosols affect the atmospheric radiative balance directly through scattering, absorption, and emission of radiation; they also affect it indirectly, by acting as cloud condensation nuclei and modifying cloud properties. The investigation of the role that dust plays on climate is among the main priorities in future climate projections. ...
... The height, structure and processes taking place in the PBL as well as the height of Saharan dust layers and theirs interaction depend on the solar radiation that reaches the Earth's atmosphere and surface, wind erosion, and wind speed. 1,2,6,8 In this paper we present and discuss Saharan dust and aerosol optical characteristics observations carried out over the city of Sofia, Bulgaria in the period from January 2013 to August 2014. ...
Atmospheric aerosol is known to considerably influence the Earth's radiative budget and to make an impact on air quality. The influence of aerosols strongly depends on their spatial distribution and optical properties. The aerosol has natural and anthropogenic origin. Aerosol types can be also classified according to their size, sources or geographical origin (desert, continental, marine etc.). Mineral dust is one of the natural aerosols presented in the atmosphere. Its main source is the Sahara desert region. Saharan aerosol layers are frequently observed in Europe by means of active and passive remote sensing devices, especially in the frame of EARLINET and ACTRIS 3, 5, 6, 7, 8, 9 . In this paper, observations of vertical distribution of aerosols and assessment of their optical properties will be presented. Two-year (2013-2014) complex measurements were carried out by a ceilometer CHM-15k (Jenoptic) and two lidars in an urban area located in a mountain valley (Sofia, Bulgaria) 1 . The ceilometer works 24 hours in automatic mode. Part of the results is compared with results obtained by lidars operating in photon counting modes for specific periods of simultaneous work 5 . Supplementary data from: two meteorological stations; HYSPLIT back trajectory model 4 ; BSC-DREAM8b dust model 9 ; and the database of atmospheric radio sounding profiles from Department of Atmospheric Engineering of Wyoming University (USA) are also used in the analysis of the obtained results.
... Aerosols may comes from both natural sources, such as volcanoes, sea salts, storms, and air-borne dust, as well as anthropogenic sources such as fossil fuels combustion, biomass burning and gas-toparticle conversion process. [3][4][5][6]. Aerosol generally shows high spatial and temporal variation, depending on the emission and dispersion process, chemical evolution, as well as meteorological process. Hence, high spatial and temporal resolution measurements, such as Lidar are very useful in air quality research [7]. ...
... A telescope, usually set up in a coaxial or biaxial configuration with respect to the laser emitter will capture the return signal (or so called backscatter signal in Lidar terminology). Due to the high temporal (in terms of seconds) and spatial (3-15 m) resolution of the Lidar system, it is very useful in visualizing the vertical distribution of aerosols, as well as the instantaneous PBL structure by using aerosols as passive traces [3][4][5]12]. Hence, the Lidar system is used during the haze event to monitor the changes of a few parameters such as aerosol backscatter coefficient (β aer ), AOD, and PBL height. ...
... In the atmosphere, there are atmospheric aerosols which play a very important role in most atmospheric processes, such as the air quality, visibility, clouds, precipitation and chemical processes. Aerosols originate from natural (sea salts, air-borne dust, volcanoes, and storms) and anthropogenic sources (fossil fuels combustion, biomass burning and gas-to-particle conversion) [1], [2], [3], [4]. They have different residence time, physical properties, chemical composition, refractive-index characteristics and climate-relevant properties due to the different sources and meteorological processes. ...
... They have different residence time, physical properties, chemical composition, refractive-index characteristics and climate-relevant properties due to the different sources and meteorological processes. In terms of Earth's radiative forcing, aerosols will affect the Earth's radiation balance directly by absorbing and scattering incoming and outgoing radiation and indirectly by acting as cloud condensation nuclei (CCN), which will then change the concentration of initial droplets, albedo, precipitation formation and lifetime of the clouds [1], [2], [3], [4]. Thus, measurements of these physical and optical properties of the particles (aerosols) are of great interest. ...
Aerosol optical depth (AOD) is the measure of aerosols distributed within a column of air from the instrument or Earth's surface to the top of the atmosphere. In this paper, we compared the AOD measured by the Raymetrics Lidar system and AERONET sunphotometer. A total of 6 days data which was collected by both instruments were compiled and compared. Generally, AOD value calculated from Lidar data are higher than that calculated from AERONET data. Differences and similarities in the AOD data trend were observed and the corresponding explanations were done. Level 1.5 data of AERONET is estimated to have an accuracy of ±0.03, thus the Lidar data should follow the trend of the AERONET. But in this regards, this study was conducted less than one month and was very difficult to justify the differences and similarities between AOD measured by the Raymetrics Lidar system and AERONET sunphotometer. So further studies for an extended period will be needed and performed with more comprehensive LIDAR measurements. The slope of the best-fit straight line for the data points between the AOD values retrieved from LIDAR and the AERONET measurements is the closest to unity and the coefficient of determination is high (above 0. 6692). Factors which affect AOD data were discussed. As a conclusion, the trends of the AOD of both systems are similar. Yet due to some external factors, the trend will be slightly different.
