NO2 vertical column density retrieval from Pandora and first comparison with GEMS data during the GMAP & SIJAQ campaign 2020

Abstract

We, for the first time, compared NO2 VCDs obtained from Ground-based Pandora spectrometer which uses direct sun measurements and those obtained from GEMS which is the first UV-VIS hyperspectral sensor onboard the geostationary earth orbit satellite during the GMAP (GEMS Map of the Air pollution) & SIJAQ (Satellite Integrated Joint monitoring of Air Quality) campaign 2020 held in winter. NO2 VCDs were retrieved using DOAS technic from four Pandora spectrometers which were located over four Seosan sites. During the inter-comparison period four Pandora spectrometers, we found 0.99 of correlation coefficient (R) between the four Pandora spectrometers. While slope and intercepts range from 0.90 to 0.99 and from – 5.15 1014 to 5.58 1014, respectively. The diurnal patterns show good agreement between NO2 VCDs measured by the Pandora and those measured by GEMS, TROPOMI (TROPOspheric Monitoring Instrument), and OMPS (Ozone Mapping and Profiler Suite). The R between NO2 VCDs obtained from the Pandora spectrometer and NO2 VCDs obtained from the GEMS range from 0.60 to 0.75. The comparison was also carried out accounting for horizontal representativeness of Pandora. This present study discuses a difference of comparison results obtained between Pandora and GEMS in cases with and without application of horizontal representativeness.