EGU2020-10230
https://doi.org/10.5194/egusphere-egu2020-10230
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

New-generation OMI NO2 Standard Product: Algorithm description and initial results

Lok Lamsal1, Nickolay Krotkov2, Alexander Vasilkov3, Sergey Marchenko3, Joanna Joiner2, Wenhan Qin3, Eun-Su Yang3, William Swartz4, Sungyeon Choi3, Zachary Fasnacht3, David Haffner3, and Bradford Fisher3
Lok Lamsal et al.
  • 1USRA/NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics, Greenbelt, MD, USA (llamsal@usra.edu)
  • 2NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics, Greenbelt, MD, USA
  • 3Science Systems and Applications, Lanham, MD, USA
  • 4John Hopkins University, Applied Physics Laboratory, Laurel, MD, USA

We present our new and improved version (version 4.0) of the NASA standard nitrogen dioxide (NO2) product from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This version incorporates the most important improvements proposed for regional OMI NO2 products by expert users, and enhances NO2 data quality on a global scale through improvements in the Air Mass Factors (AMFs) in several ways. The algorithm is based on a conceptually new, geometry-dependent Lambertian surface equivalent reflectivity (GLER) operational product. GLER is calculated using the vector radiative transfer model VLIDORT, which uses as input high–resolution bidirectional reflectance distribution function (BRDF) information from NASA’s Aqua MODIS instrument over land and the wind-dependent Cox–Munk wave-facet slope distribution over water, the latter with a contribution from the water-leaving radiance. The GLER and our corresponding, consistently retrieved effective cloud fraction and O2-O2 optical centroid cloud pressures provide inputs to the new NO2 AMF algorithm, which increases tropospheric NO2 by up to 50% in highly polluted areas; the differences include both cloud and surface BRDF effects as well as biases between the MODIS and OMI-based surface reflectance data sets. We assess the new product using independent observations from ground-based and airborne instruments. The improved NO2 data record could be beneficial for studies related to emissions and trends of nitrogen oxides (NOx) and co-emitted gases.

How to cite: Lamsal, L., Krotkov, N., Vasilkov, A., Marchenko, S., Joiner, J., Qin, W., Yang, E.-S., Swartz, W., Choi, S., Fasnacht, Z., Haffner, D., and Fisher, B.: New-generation OMI NO2 Standard Product: Algorithm description and initial results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10230, https://doi.org/10.5194/egusphere-egu2020-10230, 2020