scholarly journals Observations of the summertime atmospheric pollutants vertical distributions and the corresponding ozone production in Shanghai, China

2017 ◽  
Author(s):  
Chengzhi Xing ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Ka Lok Chan ◽  
Yang Gao ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Pearson Correlation ◽  
A Priori ◽  
Lower Troposphere ◽  
Sensitivity Study ◽  
Atmospheric Pollutants ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
Lidar Measurements ◽  
Vertical Distributions

Abstract. Ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China during May 2016 to investigate the summertime atmospheric pollutants vertical distribution. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurement using the Heidelberg Profile (HeiPro) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. MAX-DOAS measured tropospheric NO2Vertical Column Densities (VCDs) show a good agreement with OMI satellite observations with Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height, horizontal and vertical wind fields information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground and upper altitudes are not directly related to horizontal and vertical transportations. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near to the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

scholarly journals Observations of the vertical distributions of summertime atmospheric pollutants and the corresponding ozone production in Shanghai, China

2017 ◽  
Vol 17 (23) ◽  
pp. 14275-14289 ◽  
Author(s):  
Chengzhi Xing ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Ka Lok Chan ◽  
Yang Gao ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Pearson Correlation ◽  
A Priori ◽  
Lower Troposphere ◽  
Atmospheric Pollutants ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Lidar Measurements ◽  
Vertical Distributions

Abstract. Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China, during May 2016 to investigate the vertical distribution of summertime atmospheric pollutants. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori profile demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. Tropospheric NO2 vertical column densities (VCDs) measured with MAX-DOAS show a good agreement with OMI satellite observations with a Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height and horizontal and vertical wind field information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground level and upper altitudes are not directly related to horizontal and vertical transportation. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

scholarly journals MAX-DOAS measurements of NO<sub>2</sub>, SO<sub>2</sub>, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau

2020 ◽  
Vol 20 (11) ◽  
pp. 6973-6990 ◽  
Author(s):  
Jianzhong Ma ◽  
Steffen Dörner ◽  
Sebastian Donner ◽  
Junli Jin ◽  
Siyang Cheng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Trace Gases ◽  
Elevation Angle ◽  
Lower Troposphere ◽  
Statistical Error ◽  
Tropospheric Chemistry ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
The Tibetan Plateau ◽  
Mixing Ratios

Abstract. Mt. Waliguan Observatory (WLG) is a World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) global baseline station in China. WLG is located at the northeastern part of the Tibetan Plateau (36∘17′ N, 100∘54′ E, 3816 m a.s.l.) and is representative of the pristine atmosphere over the Eurasian continent. We made long-term ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements at WLG during the period 2012–2015. In this study, we retrieve the differential slant column densities (dSCDs) and estimate the tropospheric background mixing ratios of different trace gases, including NO2, SO2, HCHO, and BrO, using the measured spectra at WLG. Averaging of 10 original spectra is found to be an “optimum option” for reducing both the statistical error of the spectral retrieval and systematic errors in the analysis. The dSCDs of NO2, SO2, HCHO, and BrO under clear-sky and low-aerosol-load conditions are extracted from measured spectra at different elevation angles at WLG. By performing radiative transfer simulations with the model TRACY-2, we establish approximate relationships between the trace gas dSCDs at 1∘ elevation angle and the corresponding average tropospheric background volume mixing ratios. Mixing ratios of these trace gases in the lower troposphere over WLG are estimated to be in a range of about 7 ppt (January) to 100 ppt (May) for NO2, below 0.5 ppb for SO2, between 0.4 and 0.9 ppb for HCHO, and lower than 0.3 ppt for BrO. The chemical box model simulations constrained by the NO2 concentration from our MAX-DOAS measurements show that there is a little net ozone loss (−0.8 ppb d−1) for the free-tropospheric conditions and a little net ozone production (0.3 ppb d−1) for the boundary layer conditions over WLG during summertime. Our study provides valuable information and data sets for further investigating tropospheric chemistry in the background atmosphere and its links to anthropogenic activities.

Evaluation of a high resolution regional atmospheric chemistry model using MAX-DOAS and in situ NO2 measurements

2021 ◽  
Author(s):  
Vinod Kumar ◽  
Julia Remmers ◽  
Steffen Beirle ◽  
Astrid Kerkweg ◽  
Jos Lelieveld ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Pearson Correlation ◽  
Surface Concentration ◽  
Ozone Production ◽  
Vertical Column ◽  
The Impact ◽  
The Vertical Distribution

&lt;p&gt;Regional atmospheric chemistry models are adopted for simulating concentrations of atmospheric components at high resolution and quantifying the impact of localized emissions (e.g. industrial and urban clusters) on the non-linear chemical processes, e.g. ozone production. However, their evaluation is challenging due to the limited availability of high spatiotemporally resolved reference datasets. For the same reason, the vertical distribution of pollutants simulated by the model is especially arduous to assess.&lt;/p&gt;&lt;p&gt;Here, we present regional atmospheric chemistry model studies with spatial resolution up to 2.2 &amp;#215; 2.2 km&lt;sup&gt;2&lt;/sup&gt; focused around Germany for May 2018 using the MECO(n) model system. Using a network of surface concentration measurements at background, near traffic and industrial locations, we evaluate the spatial distribution of NO&lt;sub&gt;2&lt;/sub&gt; simulated by the model. The highly resolved model together with a comparable resolution and up-to-date input emissions inventory, was found to perform best in reproducing the spatial distribution of NO&lt;sub&gt;2&lt;/sub&gt; surface volume mixing ratios (VMRs). We propose a computationally efficient approach to account for the diurnal and day of the week variability of input anthropogenic emissions (e.g. from road transport), which proved to be crucial for resolving the temporal variability of NO&lt;sub&gt;2&lt;/sub&gt; surface VMRs.&lt;/p&gt;&lt;p&gt;The simulated NO&lt;sub&gt;2&lt;/sub&gt; tropospheric vertical column densities were evaluated by employing the measurements of a 4-azimuth MAX-DOAS instrument in Mainz. Generally, such comparisons do not account for the spatial sensitivity volume of the MAX-DOAS measurements, the change of sensitivity within this volume and the spatial heterogeneity of NO&lt;sub&gt;2&lt;/sub&gt;. We therefore apply a consistent approach of comparison of the differential slant column densities (dSCDs), which overcomes these limitations. Moreover, the dSCDs are obtained for several elevation and azimuth angles, which are characterized by distinctive sensitivity for different vertical levels within the boundary layer and different horizontal representativeness. Hence, also an evaluation of the model in simulating the vertical distribution of NO&lt;sub&gt;2&lt;/sub&gt; can be performed with this approach using continuous MAX-DOAS measurements spanning long time periods. We found that the model performs well with respect to the measured dSCDs at low elevation angles (&lt; 8&amp;#176;) with an overall bias between +14 and -9%, and Pearson correlation coefficients between 0.5 and 0.8 for the different azimuth viewing directions.&lt;/p&gt;

scholarly journals Retrieval of atmospheric CO<sub>2</sub> vertical profiles from ground-based near-infrared spectra

2020 ◽  
Author(s):  
Sébastien Roche ◽  
Kimberly Strong ◽  
Debra Wunch ◽  
Joseph Mendonca ◽  
Colm Sweeney ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Near Infrared ◽  
A Priori ◽  
Lower Troposphere ◽  
Sensitivity Study ◽  
Total Carbon ◽  
Solar Absorption ◽  
Line Shapes ◽  
Vertical Variations ◽  
Co2 Profile

Abstract. We evaluate vertical profile retrievals of CO2 from 0.02 cm−1 resolution ground-based near-infrared solar absorption spectra with the GFIT2 algorithm, using improved spectroscopic linelists and line shapes. With these improvements, CO2 profiles were obtained from sequential retrievals in five spectral windows with different vertical sensitivities. A sensitivity study using synthetic spectra shows that the leading source of uncertainty in the retrieved CO2 profiles is the error in the a priori temperature profile, even with 3-hourly reanalysis a priori profiles. A 2 °C error in the temperature profile in the lower troposphere between 0.6 and 0.85 atm causes deviations in the retrieved CO2 profiles that are larger than the typical vertical variations of CO2. To distinguish the effect of errors in the a priori meteorology and trace gas concentration profiles from those in the instrument alignment and spectroscopic parameters, we retrieve CO2 profiles from atmospheric spectra while using an a priori built from coincident AirCore, radiosonde, and surface in situ measurements at the Lamont, Oklahoma (USA) Total Carbon Column Observing Network station. In those cases, the deviations in retrieved CO2 profiles are also larger than typical vertical variations of CO2, suggesting that remaining errors in the forward model limit the accuracy of the retrieved profiles. Implementing a temperature retrieval or correction, and quantifying and modeling an imperfect instrument alignment, are critical to improve CO2 profile retrievals. Without significant advances in modeling imperfect instrument alignment, and improvements in the accuracy of the temperature profile, the CO2 profile retrieval with GFIT2 presents no clear advantage over scaling retrievals for the purpose of ascertaining the total column.

scholarly journals Investigation of the diurnal pattern of the vertical distribution of pollen in the lower troposphere using LIDAR

2013 ◽  
Vol 13 (15) ◽  
pp. 7619-7629 ◽  
Author(s):  
Y. M. Noh ◽  
H. Lee ◽  
D. Mueller ◽  
K. Lee ◽  
D. Shin ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Meteorological Data ◽  
Turbulent Transport ◽  
Lower Troposphere ◽  
Diurnal Pattern ◽  
Pollen Concentrations ◽  
Lidar Measurements ◽  
The Vertical Distribution ◽  
532 Nm ◽  
Depolarization Ratios

Abstract. The diurnal pattern of the vertical distribution of biogenic pollen in the lower troposphere was investigated by LIDAR. Meteorological data were taken at the ground. Pollen concentrations were measured at the surface using a Burkard 7-day-recording volumetric spore sampler. Aerosol extinction coefficients and depolarization ratios at 532 nm were obtained from LIDAR measurements in spring (4 May–2 June) 2009 in Gwangju, South Korea. Linear volume depolarization ratios varied between 0.08 and 0.14 and were observed only during daytime (09:00–17:00 local time (LT)) during days of high pollen concentration (4 to 9 May). Daily average pollen concentrations ranged 1000–2500 cm−3 in the same period. The temporal evolution of the vertical distribution of the linear volume depolarization ratio showed a specific diurnal pattern. Linear volume depolarization ratios of more than 0.06, were measured near the surface in the morning. High depolarization ratios were detected up to 2 km aboveground between 12:00 and 14:00 LT, whereas high depolarization ratios were observed only close to the surface after 17:00 LT. Low values of depolarization ratios (≤0.05) were detected after 18:00 LT until the next morning. During the measurement period, the daily variations of the high depolarization ratios close to the surface showed correlation to number concentration measurements of pollen. This finding suggests that high depolarization ratios could be attributed to enhanced pollen concentrations. The diurnal characteristics of the high values of depolarization ratios are thought to be closely associated with turbulent transport. Diurnal and vertical characteristics of pollen, if measured continuously, could be used to improve the accuracy of pollen-forecasting models via data assimilation studies.

scholarly journals Retrieval of atmospheric CO<sub>2</sub> vertical profiles from ground-based near-infrared spectra

2021 ◽  
Vol 14 (4) ◽  
pp. 3087-3118
Author(s):  
Sébastien Roche ◽  
Kimberly Strong ◽  
Debra Wunch ◽  
Joseph Mendonca ◽  
Colm Sweeney ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Near Infrared ◽  
A Priori ◽  
Lower Troposphere ◽  
Sensitivity Study ◽  
Total Carbon ◽  
Solar Absorption ◽  
Line Shapes ◽  
Vertical Variations ◽  
Co2 Profile

Abstract. We evaluate vertical profile retrievals of CO2 from 0.02 cm−1 resolution ground-based near-infrared solar absorption spectra with the GFIT2 algorithm, using improved spectroscopic line lists and line shapes. With these improvements, CO2 profiles were obtained from sequential retrievals in five spectral windows with different vertical sensitivities using synthetic and real spectra. A sensitivity study using synthetic spectra shows that the leading source of uncertainty in the retrieved CO2 profiles is the error in the a priori temperature profile, even with 3-hourly reanalysis a priori profiles. A 2 ∘C error in the temperature profile in the lower troposphere between 0.6 and 0.85 atm causes deviations in the retrieved CO2 profiles that are larger than the typical vertical variations of CO2. To distinguish the effect of errors in the a priori meteorology and trace gas concentration profiles from those in the instrument alignment and spectroscopic parameters, we retrieve CO2 profiles from atmospheric spectra while using an a priori profile built from coincident AirCore, radiosonde, and surface in situ measurements at the Lamont, Oklahoma (USA), Total Carbon Column Observing Network station. In those cases, the deviations in retrieved CO2 profiles are also larger than typical vertical variations of CO2, suggesting that remaining errors in the forward model limit the accuracy of the retrieved profiles. Implementing a temperature retrieval or correction and quantifying and modeling an imperfect instrument alignment are critical to improve CO2 profile retrievals. Without significant advances in modeling imperfect instrument alignment, and improvements in the accuracy of the temperature profile, the CO2 profile retrieval with GFIT2 presents no clear advantage over scaling retrievals for the purpose of ascertaining the total column.

scholarly journals Retrieval and evaluation of tropospheric aerosol extinction profiles using MAX-DOAS measurements over Athens, Greece

2020 ◽  
Author(s):  
Myrto Gratsea ◽  
Tim Bösch ◽  
Panos Kokkalis ◽  
Andreas Richter ◽  
Mihalis Vrekoussis ◽  
...  
Keyword(s):  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
The Sun ◽  
Tropospheric Aerosol ◽  
Lidar Measurements ◽  
Vertical Distributions ◽  
Term Basis ◽  
Photometric Measurements ◽  
First Time

Abstract. In this study, we report on the retrieval of aerosol extinction profiles from ground-based scattered sunlight multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements, carried out at Athens, Greece. It is the first time that aerosol profiles are retrieved from MAX-DOAS measurements in Athens. The reported aerosol vertical distributions at 477 nm are derived from the oxygen dimer (O4) differential slant column density observations at different elevation angles by applying the BOREAS retrieval algorithm. Four case studies have been selected for validation purposes; the retrieved aerosol profiles and the corresponding aerosol optical depths (AODs) from the MAX-DOAS are compared with lidar extinction profiles and with sun photometric measurements (AERONET observations), respectively. Despite the different approach of each method regarding the retrieval of the aerosol information, the comparison with the lidar measurements at 532 nm reveals a very good agreement in terms of vertical distribution, with r > 0.85 in all cases. The AODs from the MAX-DOAS and the sun-photometer (the latter at 500 nm) show a satisfactory correlation (with r ≈ 0.6 in three out of the four cases). The comparison indicates that the MAX-DOAS systematically underestimates the AOD in the cases of large particles (small Ångström exponent) and for measurements at small relative azimuthal angles between the viewing direction and the Sun. Better agreement is achieved in the morning, at large relative azimuthal angles. Overall, the aerosol profiles retrieved from MAX-DOAS measurements are of good quality; thus, new perspectives are opened up for assessing urban aerosol pollution on a long term-basis in Athens from continuous and uninterrupted MAX-DOAS measurements.

TROPOMI observations of total column water vapor

2021 ◽  
Author(s):  
Ka Lok Chan ◽  
Sander Slijkhuis ◽  
Katerina Garane ◽  
Pieter Valks ◽  
Diego Loyola
Keyword(s):  
Water Vapor ◽  
Pearson Correlation ◽  
A Priori ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Blue Band ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
Typical Satellite ◽  
Total Column

&lt;p&gt;We present the total column water vapor (TCWV) retrieval for the TROPOspheric Monitoring Instrument (TROPOMI) observations in the blue band. The retrieval was first developed to retrieve TCWV from Global Ozone Monitoring Experience 2 (GOME-2). We have modified the settings of the retrieval to adapt it for TROPOMI observations. The TROPOMI TCWV retrieval algorithm consists of two major steps. The first step is the retrieval of water vapor slant columns by applying the differential optical absorption spectroscopy (DOAS) technique to TROPOMI observations in the blue band. The retrieved water vapor slant columns are then converted to vertical columns using air mass factors (AMFs). An iterative optimization has been developed to dynamically find the optimal a priori water vapor profile for AMF calculation. The dynamic search algorithm makes use of the fact that the vertical distribution of water vapor is strongly correlated to the total column amount. This makes the algorithm better suited for climate studies compared to typical satellite retrievals with static a priori or vertical profile information from the chemistry transport model (CTM). Details of the TCWV retrieval are presented. The TCWV retrieval algorithm is applied to TROPOMI observations. The results are validated by comparing to Ozone Monitoring Instrument (OMI), GOME-2 and Special Sensor Microwave Imager Sounder (SSMIS) satellite observations. TCWV derived from TROPOMI observations agree well with the other data sets with Pearson correlation coefficient (R) ranging from 0.94 to 0.99. The correlation is slight better during winter time of the northern hemisphere. Small discrepancies are found among TROPOMI, OMI, GOME-2 and SSMIS observations. The discrepancies are mainly due to differences in measurement time and cloud filtering. More detailed validation against ground based sun-photometer observations are presented separately in this session*.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;*see the respective abstract by Katerina Garane.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document