NO2 retrievals from NOAA-20 OMPS: Algorithm, evaluation, and observations of drastic changes during COVID-19. (1st December 2022)

• Record Type: Journal Article
• Authors: Huang, Xinzhou; Yang, Kai; Kondragunta, Shobha; Wei, Zigang; Valin, Lukas; Szykman, James; Goldberg, Mitch
• Is Part Of: Atmospheric environment. Volume 290(2022)
• Publication Date: 2022-12-01
• Subjects: NOAA-20 -- OMPS -- Stratosphere and troposphere NO2 -- COVID-19; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2022.119367
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: We present the first NO2 measurements from the Nadir Mapper of Ozone Mapping and Profiler Suite (OMPS) instrument aboard the NOAA-20 satellite. NOAA-20 OMPS was launched in November 2017, with a nadir resolution of 17 × 13 km 2 similar to the Ozone Monitoring Instrument (OMI). The retrieval of NOAA-20 NO2 vertical columns were achieved through the Direct Vertical Column Fitting (DVCF) algorithm, which was uniquely designed and successfully used to retrieve NO2 from OMPS aboard Suomi National Polar-orbiting Partnership (SNPP) spacecraft, predecessor to NOAA-20. Observations from NOAA-20 reveal a 20–40% decline in regional tropospheric NO2 in January–April 2020 due to COVID-19 lockdown, consistent with the findings from other satellite observations. The NO2 retrievals are preliminarily validated against ground-based Pandora spectrometer measurements over the New York City area as well as other U.S. Pandora locations. It shows OMPS total columns tend to be lower in polluted urban regions and higher in clean areas/episodes associated with relatively small NO2 total columns, but generally the agreement is within ±2.5 × 10 15 molecules/cm 2 . Comparisons of stratospheric NO2 columns exhibit the excellent agreement between OMPS and OMI, validating OMPS capability in capturing the stratospheric background accurately. These results demonstrate the high sensitivity of OMPS to tropospheric NO2 and highlight its potential use for extending the long-term global NO2 record. Highlights: Daily global NO2 distribution can be mapped by NOAA-20 OMPS measurements. NOAA-20 OMPS detects a large decline (20–40%) of tropospheric NO2 due to COVID-19 lockdown. OMPS tropospheric NO2 correlates well with ground-based Pandora measurements. OMPS stratospheric NO2 agrees excellently with OMI observations.