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Terra Nova Bay Station, Antarctica. NO 2 slant column (DSCD) variations during 13 February 2001 (left and lower axes) and 15 March 2001 (right and upper axes). On 13 February no substantial chemical processes contribute to NO 2 diurnal variation a.m. DSCD , p.m. DSCD. On 15 March, the decrease in the daylight period causes the deactivation of photochemical reactions. The formation of N 2 O 5 during the night and its subsequent photolysis during the day lead to greater NO 2 DSCDs in the evening twilight than in the morning.
Source publication
Several UV-visible spectrometers have been developed at the ISAC-CNR Institute. Differential Optical Absorption Spectroscopy (DOAS) methodology is applied to their measurements to monitor the amounts of stratospheric trace gases: mainly ozone (O-3) and nitrogen dioxide (NO2) which is involved in the ozone cycle. Observations of the scattered zenith...
Contexts in source publication
Context 1
... the following results are presented as vertical or total column densities (except for figure 5 where the slant columns (DSCD) are plotted). The NO 2 VCDs are calculated by applying to the measured column (SCD, obtained with the DOAS algorithms ) the AMF computed with the AMEFCO radiative transfer model ( Petritoli et al. 1999). ...
Context 2
... order to clarify the daily variation of NO 2 at high latitudes, the NO 2 DSCD values are plotted as a function of the SZA for two different days in 2001 ( figure 5). On 13 February, the NO 2 a.m. and p.m. DSCD (figure 5, grey circles and white squares, respectively) are of the same magnitude: this means that no substantial photochemical processes contributed to the NO 2 diurnal variation. ...
Context 3
... DSCD behaviour is different for 15 March, when the a.m. DSCD (figure 5, white circles) values are systematically lower than the NO 2 p.m. DSCD ( figure 5, grey squares), due to the deactivation of photochemical reactions caused mainly by the decrease of the daylight period. In fact, the formation of N 2 O 5 during the night and its subsequent photolysis during the day, lead to greater NO 2 DSCD in the evening twilight than in the morning ( Noxon et al. 1979). ...
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Citations
... Studying Noxon cliff characteristics for a long time depended on numerical modeling (e.g., Solomon and Garcia, 1983;Toon et al., 1989;Garcia and Solomon, 1994;Struthers et al., 2004), ground-based observations (e.g., Gil and Cacho, 1992;Solomon et al., 1993;Kondo et al., 1994;Sanders et al., 1999;Struthers et al., 2004;Bortoli et al., 2005;Yela et al., 2005;Cook and Roscoe, 2009), and aircraft or balloon measurement campaigns over Antarctica (e.g., Goldman et al., 1978;Pommereau and Goutail, 1988;Fahey et al., 1989). ...
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... This kind of instrument was initially developed at CNR-ISAC in the 90s and improved over the years in collaboration with the University of Evora (Portugal) [34]. Several instruments of this family are located in permanent observation stations: the Ottavio Vittori facility at Mt. Cimone (44.11 • N, 10.42 • E-Italy) [35,36], the "Mario Zucchelli" station (74.70 • S, 164.12 • E-Antarctica) [34], the atmospheric observatory in Bologna (44.52 • N, 11.42 • E-Italy) and the Evora Atmospheric Science Observatory (EVASO) in Evora (38.56 • N, 7.90 • W-Portugal) [33]. In the scope of the I-AMICA project (http://www.i-amica.it, ...
... This instrument uses the same monochromator as all the other systems installed in the above mentioned stations, with the dispersive element of 1200 grooves/mm and mean spectral resolution of 0.5 nm in the 300-800 nm spectral range. A detailed description of the mechanical and electronic components, together with the adopted optical layout and explanations of the measurement principles adopted in the most recent versions of these instruments, are available in [34,37]. ...
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The Intercomparison of nitrogen dioxide (NO<sub>2</sub>) vertical profiles, derived from the satellite based HALogen Occultation Experiment (HALOE) measurements and from the ground based UV-VIS spectrometer GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences) observations at the Mario Zucchelli Station (MZS), in Antarctica, are done for the first time. It is shown here that both datasets are in good agreement showing the same features in terms of magnitude, profile structure, and temporal variations.
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The environmental impact of large vessel exhaust gases on port and coastal areas is a subject of great interest due both to increasing maritime traffic and the vicinity to highly populated urban zones. In lagoon cities the pollution from maritime traffic is greater than in other coastal areas. Therefore monitoring and evaluation of pollutants produced by ships navigating through the principal transport channels become necessary. In the case of Venice, the Giudecca Channel, crossing the city centre, is used both by urban maritime traffic and by large vessels docking in the port.
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This paper presents an evaluation of the nitrogen dioxide (NO2) trend inferred from UV–visible zenith-sky measurements performed at the ‘Ottavio Vittori’ ground-based research station (www.isac.cnr.it/cimone) at Monte Cimone (44.18◦ N, 10.7◦ E, 2165 m above sea level (a.s.l.)). Experimental data series are obtained from the measured spectra adopting a retrieval procedure according to differential optical absorption spectroscopy (DOAS) methodology. Data series cover the period from 1993 to 2009, with limited interruptions due to technical maintenance of the instrument or poor meteorological conditions. The NO2 trends are calculated with a linear regression model considering different factors assumed to contribute to NO2 atmospheric content. Before running the model, a procedure for data quality control was applied to reduce or exclude the influence of measurements affected by poor meteorological conditions or the vertical transport of polluted air masses from the lower troposphere. The negative trends obtained for sunrise (a.m.) and sunset (p.m.) NO2 measurements are in good agreement with previous studies accomplished for ground-based stations in the northern hemisphere.
... The equipment consisted of: i) the UVeVis remote sensing DOAS system, developed at ISAC, named TropoGAS (Tropospheric Gas Analyzer Spectrometer) (Masieri et al., 2009) shown in Fig. 3a. TropoGAS belongs to the family of GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences) systems (Evangelisti et al., 1995;Petritoli et al., 2002;Bortoli et al., 2005) to which, the SPA-TRAM (SPectrometer for Atmospheric TRAcers Monitoring) instrument was recently added (Bortoli, 2005;Bortoli et al., 2009aBortoli et al., , 2009b. A complete description of TropoGAS or GAS-COD systems is beyond the scope of this work, and a full explanation of the mechanical and electronic components together with the adopted optical layout and principles of measurements can be found in the already cited papers and particularly in Bortoli et al. (2010). ...
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Daily total ozone column (TOC) measurements from the Brewer spectroradiometer located at El Arenosillo (Spain) and the Spectrometer for Atmospheric TRAcers Monitoring (SPATRAM) located at Évora (Portugal) are analyzed for the period 2006-2008. The main goal of this study is to compare TOC estimates retrieved with the passive differential optical absorption spectroscopy (DOAS) methodology from zenith-sky observations by the SPATRAM spectrometer with highly accurate TOC estimates retrieved from direct-sun recordings by a well-calibrated Brewer instrument. On average, SPATRAM TOC estimates are (1.69 ± 0.18)% smaller than collocated Brewer TOC estimates. Significant relative differences between SPATRAM and Brewer total ozone data are detected in some periods caused by the influence of high aerosol load episodes over the SPATRAM data. Satellite data recorded by the ozone monitoring instrument (OMI)-DOAS algorithm aboard the NASA EOS-Aura satellite have been used to quantify the natural spatial variability of TOC over the region of interest as a potential source of uncertainty in the SPATRAM-Brewer comparison. Our results show that the differences observed between both systems is not associated with the natural spatial variability of TOC. In addition, the OMI-DOAS total ozone data have been compared to the ground-based spectroradiometer data showing an excellent agreement for the Brewer spectroradiometer (R2 ˜ 0.95) and a fairly good agreement for the SPATRAM instrument (R2 ˜ 0.89).
... Analyzing the plot in Figure 3 it can be noted that during 2002, the NO 2 VCDs obtained are lower than in 2003 , but for 2002 again, the AM-PM differences are much larger than in the other year. This anomalous behavior can be explained within the framework of the sudden stratospheric warming (SSW) which occurred in the SH during austral spring 2002 [23][24][25][26][27] . ...
The GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences) has been installed at the 'Mario Zucchelli' Antarctic station since 1996. It measures the zenith sky radiation in the 405-465 nm spectral range in unattended and automatic mode. The application to the spectral data of the DOAS (Differential Optical Absorption Spectroscopy) algorithms coupled with a Radiative Transfer Model (RTM) for the computation of the Air Mass Factor (AMF), allows for the retrieval of the total content of the main absorber in this spectral range, namely nitrogen dioxide (NO2). Moreover, the application of sophisticated inversion schemes to the output of the DOAS program, using the AMF matrix as the kernel of the inversion algorithm, permits the determination of the vertical distribution of the above mentioned compound. The full dataset of the spectral data obtained with GASCOD during the period 1996-2008, was re-analyzed with a modified version of the software tool previously utilized. Even if the spectral range examined with GASCOD is not the most favorable for the ozone total column and vertical profile retrieval, the re-processing of the spectral data allowed for the determination of the total ozone columns (TOC). The uncertainties range from 4% to 8% for ozone and 3% to 6% for NO2. The peculiar features of the seasonal variation of NO2 total columns (i.e. the normal decreasing during the austral fall and the irregular growing towards the summer month) are presented and discussed. The confirmations of the significant declining of the ozone total columns during the 'Ozone Hole' periods (mid-August to mid-October) are reported. The vertical distributions obtained for the preceding atmospheric compounds are shown and examined.
... Unfortunately, the vertical resolution of the retrieved vertical profiles is limited to 5 km, due to the low variation of the AMF for high values of SZA. The results obtained with this type of measurements are mainly used in studies concerning modifications in the total content of atmospheric compounds, mainly located in the stratosphere [8][9][10][11][12] . These works are mostly inserted in the frame of global warming and climate changes. ...
A simple method to determine the vertical distribution of a pollutant gas, namely NO2, by means of the spectral measurements obtained with a scan-DOAS spectrometer, is presented. The developed technique can be summarized as follows: i) a series of quasi simultaneous measurements in the zenith and in others directions allowing for the determination of the Slant Column Density of NO2 for different elevation angles; ii) an active DOAS measurement for the determination of the NO2 concentration at the ground; iii) a set of Radiative Transfer Model (RTM) calculation of the scattering distance from the spectrometer, for a set of visibility values; iv) a recursive procedure of profile calculation
starting from the first measurement and subtracting the value of NO2 Slant Column Density (SCD) retrieved from the
measurement taken at the previous angle of sight. Measurements are carried out during summer 2007 in S. Pietro
Capofiume (Bologna-Italy). The vertical distribution for NO2 obtained with the above described method has been
compared with the profiles calculated with the GAMES (Gas Aerosol Modelling Evaluation System) model. The results of this comparison show some differences between the modelled and the measured profiles, probably due to box approximations in RTM calculation for measured profiles and to the large pixel grid (about 10x10 km2), for model
evaluation.
