A research product for tropospheric NO.sub.2 columns from Geostationary Environment Monitoring Spectrometer based on Peking University OMI NO.sub.2 algorithm

• Published in: Atmospheric measurement techniques Vol. 16; no. 19; pp. 4643 - 9285
• Main Authors: Zhang, Yuhang, Lin, Jintai, Kim, Jhoon, Lee, Hanlim, Park, Junsung, Hong, Hyunkee, Van Roozendael, Michel, Hendrick, Francois, Wang, Ting, Wang, Pucai, He, Qin, Qin, Kai, Choi, Yongjoo, Kanaya, Yugo, Xu, Jin, Xie, Pinhua, Tian, Xin, Zhang, Sanbao, Wang, Shanshan, Cheng, Siyang, Cheng, Xinghong, Ma, Jianzhong, Wagner, Thomas, Spurr, Robert, Chen, Lulu, Kong, Hao, Liu, Mengyao
• Format: Journal Article
• Language: English
• Published: Copernicus GmbH 12.10.2023
• Subjects: Algorithms; Nitrogen dioxide
• ISSN: 1867-1381

Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO.sub.2) retrieved from sun-synchronous satellite instruments have provided abundant NO.sub.2 data for environmental studies, but such data are limited by retrieval uncertainties and insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEMS) launched in February 2020 monitors NO.sub.2 at an unprecedented hourly resolution during the daytime. Here we present a research product for tropospheric NO.sub.2 VCDs, referred to as POMINO-GEMS (where POMINO is the Peking University OMI NO.sub.2 algorithm). We develop a hybrid retrieval method combining GEMS, TROPOMI (TROPOspheric Monitoring Instrument) and GEOS-CF (Global Earth Observing System Composition Forecast) data to generate hourly tropospheric NO.sub.2 slant column densities (SCDs). We then derive tropospheric NO.sub.2 air mass factors (AMFs) with explicit corrections for surface reflectance anisotropy and aerosol optical effects through parallelized pixel-by-pixel radiative transfer calculations. Prerequisite cloud parameters are retrieved with the O.sub.2 -O.sub.2 algorithm by using ancillary parameters consistent with those used in NO.sub.2 AMF calculations.