Satellite remote-sensing capability to assess tropospheric-column ratios of formaldehyde and nitrogen dioxide: case study during the Long Island Sound Tropospheric Ozone Study 2018 (LISTOS 2018) field campaign

Campaignaveraged uncertainties in the three satellite retrievals (NASA OMI; Quality Assurance for Essential Climate Variables, QA4ECV OMI; and TROPOMI) of NO2 were generally similar, with TROPOMI retrievals having slightly less spread in the data compared to OMI. The three satellite products differed more when evaluating HCHO retrievals. Campaignaveraged tropospheric HCHO retrievals all had linear regression slopes similar to 0 :5 and NMBs of 39 %, 17 %, 13 %, and 23% for NASA OMI, QA4ECV OMI, and TROPOMI at finer (0 :05 degrees x 0 :05 degrees) and coarser (0 :15 degrees x 0 :15 degrees) spatial resolution, respectively.

Campaign-averaged uncertainty values (root mean square error, RMSE) in NASA and QA4ECV OMI HCHO retrievals were similar to 9 :0 x 10(15) molecules cm(-2) ( similar to 50 %-55% of mean column abundance), and the higher-spatial-resolution retrievals from TROPOMI resulted in RMSE values similar to 30% lower. Spatially averaging TROPOMI tropospheric-column HCHO, along with NO2 and FNRs, to resolutions similar to the OMI reduced the uncertainty in