Acta Optica Sinica, Volume. 44, Issue 24, 2401007(2024)
Quality Evaluation and Improvement of Hourly Tropospheric NO2 Data from GEMS: A Case Study in East China
Figures & Tables(10)
Fig. 1. Correlation analysis of GEMS tropospheric NO2 data product. (a) Scatter plots of comparison between TROPOMI and GEMS observations; (b) scatter plots of comparison between MAX-DOAS and GEMS observations
Fig. 3. Distribution of GEMS monthly mean tropospheric NO2 VCDs by hour in April 2023
Fig. 4. NO2 mass concentrations and VCDs on March 4, 2023 in Shanghai. (a) Spatial distribution of air quality monitoring stations in Shanghai; (b) comparison of hourly normalized NO2 data product change trends between ground-based stations and GEMS observations; (c) distribution of tropospheric NO2 in Shanghai observed by GEMS and TROPOMI
Fig. 5. Spatial coverage and observation coverage of GEMS. (a) Distribution of observation coverage at 13:45 for different time periods; (b) distribution of mean CF at 13:45 for different time periods in East China
Fig. 6. Reconstruction results of GEMS tropospheric NO2 data product. (a) Comparison between original data and reconstructed data; (b) scatter plot of comparison between TROPOMI observations and reconstructed data; (c) scatter plot of comparison between MAX-DOAS observations and reconstructed data
Table 1. Information of the main payloads for NO2 observation
View tableTable 1. Information of the main payloads for NO2 observation
Satellite Payload Main agency Operational period Spatial resolution /（km×km） ERS-2 GOME ESA （European Space Agency） 1995‒2003 40×320 ENVISAT SCIAMACHY ESA 2002‒2012 30×60 AURA OMI NASA
（National Aeronautics and Space Administration）
2004‒ 13×24 MetOp-A
MetOp-B
MetOp-C
GOME-2 ESA 2006‒2021
2012‒
2018‒
40×80/40×40
40×80
40×80
Sentinel-5P TROPOMI ESA 2017‒ 3.5×7
（before 2019-08-06）
3.5×5.5
（after 2019-08-06）
GF-5 EMI CNSA
（China National Space Administration）
2018‒2020 13×48 GEO-KOMPSAT-2B GEMS NIER
（National Institute of Environmental Research）
2020‒ 3.5×8
Table 2. Quality control criteria of satellite data
View tableTable 2. Quality control criteria of satellite data
GEMS TROPOMI Quality control indicator Criteria Quality control indicator Criteria Solar zenith angle <70° qa （quality assurance value） >0.75 Reflectivity <0.3 （removes cloud-covered scenes with cloud radiance fraction >0.5） Cloud fraction <0.3
Table 3. Impact of quality control indicators on data volume
View tableTable 3. Impact of quality control indicators on data volume
Quality control criteria Original data Solar zenith angle <70° Reflectivity <0.3 Cloud fraction<0.3 Combined criteria Total amount of data 29978621 29978621 29972671 13228806 13227486 Percentage of
remaining data /%
100.00 100.00 99.98 44.13 44.12
Table 4. Spatial coverage of GEMS data before and after quality control in each period
View tableTable 4. Spatial coverage of GEMS data before and after quality control in each period
Period Spatial coverage /% 06：45 07：45 08：45 09：45 10：45 11：45 12：45 13：45 14：45 15：45 Mode HE HK FC FW 1
（2022-11-23‒2023-01-31）
X X 0.79
0.00 91.59
34.69 99.48
38.96 99.10
40.73 99.95
41.79 99.97
41.63 X X 2
（2023-02-01‒2023-02-27）
X X 3.70
2.15 89.27
30.53 99.97
34.93 99.97
36.29 96.79
37.31 99.96
37.13 99.97
36.29 X 3
（2023-02-28‒2023-03-30）
X 0.00
0.00 58.89
28.67 99.75
46.75 99.99
47.95 99.98
47.83 99.98
48.12 99.97
46.61 99.98
45.27 X 4
（2023-04-01‒2023-04-30）
0.00
0.00 92.54
37.03 99.99
40.27 99.98
41.50 99.95
41.49 99.91
41.29 99.86
40.76 99.86
39.88 99.90
39.34 96.61
36.63
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Hongrui Gao, Kai Qin, Qin He, Junting Kang. Quality Evaluation and Improvement of Hourly Tropospheric NO2 Data from GEMS: A Case Study in East China[J]. Acta Optica Sinica, 2024, 44(24): 2401007
Paper Information
Category: Atmospheric Optics and Oceanic Optics
Received: Apr. 9, 2024
Accepted: Jun. 18, 2024
Published Online: Dec. 17, 2024
The Author Email: Qin Kai (qinkai@cumt.edu.cn)
CSTR:32393.14.AOS240826
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