A003-0009
Geometry-dependent Lambertian-equivalent reflectivity (GLER) products for TROPOMI and OMI

Monday, 7 December 2020
Poster
Wenhan Qin1, Zachary Fasnacht1, Lok N Lamsal2, Bradford L Fisher1, Joanna Joiner3, Alexander P Vasilkov1, Nickolay Anatoly Krotkov4 and David P Haffner1, (1)Science Systems and Applications, Inc., Lanham, MD, United States, (2)Universities Space Research Association Columbia, Columbia, MD, United States, (3)NASA GSFC, Greenbelt, MD, United States, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States
Abstract:
Satellite retrievals of pollution trace gases, aerosols and clouds from UV/Visible spectrometers require the proper characterization of anisotropic surface reflection for accurate results. The NASA OMI core team developed a Geometry-dependent Lambertian-equivalent surface reflectivity product (GLER) that captures the solar and satellite viewing angle dependence as well as accounts for seasonal (e.g., vegetation, snow) and longer-term changes (e.g., land use). The GLER product is based on MODIS bi-directional reflectance distribution function (BRDF) products over land and Cox-Munk surface wave slope distribution with a contribution from water-leaving radiance over water. Version 1 GLER defined for each OMI Field-of-View (FoV) is available from NASA Goddard Earth Sciences Data and Information Services Center (https://doi.org/10.5067/AURA/OMI/DATA2032). GLER has been implemented in recently released NASA OMI version 4 NO2 retrievals with minimal changes to the algorithm (https://doi.org/10.5067/ Aura/OMI/DATA2017). Here, we present version 2 OMI GLER which includes (1) higher resolution (4 km) Interactive Multi-sensor Snow and Ice Mapping System (IMS) product; (2) improved surface pressure calculation using hourly 0.25 x 0.25 degree Global Modeling Initiative (GMI) replay data from NASA Global Modeling and Assimilation Office (GMAO), and (3) additional wavelengths.

We developed a similar GLER product for the European Space Agency (ESA) Copernicus Sentinel 5 precursor Tropospheric Monitoring Instrument (TROPOMI). To evaluate the product, we compare TROPOMI GLER with LER derived directly from TROPOMI radiance under cloud free conditions, as well as with the low spatial resolution surface LER climatology currently used in standard TROPOMI NO2 retrievals. We focus our analysis on cities adjacent to oceans and mountains to highlight the advantage of TROPOMI’s high spatial resolution. We also present the impact of GLER on the TROPOMI NO2 retrievals.

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