TROPOMI Tropospheric Column NO2 and GOES-16 Geostationary Lightning Mapper Flashes: An Initial Investigation of Lightning NOx Production

Deep convective clouds affect atmospheric chemistry in a variety of ways. Lightning produces nitric oxide (NO), which quickly comes into equilibrium with NO₂ in the atmosphere. However, global production of NO_x (NO + NO₂) from lightning is uncertain by a factor of four. The combination of data from the TROPOMI and GLM instruments will yield the most detailed information to date on production of NO_x by lightning and reduce this uncertainty. The TROPOMI instrument on the European Space Agency Sentinel 5P satellite provides high spatial resolution (3.5 km x 7 km) NO₂ tropospheric column data daily over the entire globe, with an overpass time of approximately 1330 LT. The GLM instrument on the NOAA GOES-16 satellite located at the GOES-East position (~75 degrees W) provides a continuous record of lightning flashes over North and South America and adjacent ocean areas at 10 km resolution. Gridded flash counts will be created for 15-minute periods, and detection efficiencies will be applied to these data. We will examine the NO₂ vertical column density data over highly reflective deep convective clouds in rural/remote areas and correlate the NO₂ amounts with GLM flash counts over periods of time (flash windows) ranging from 0.5 to 6 hours prior to the TROPOMI overpass as an initial demonstration of the relationship between these two data sets. This initial analysis will be conducted for the 2018 warm season over North America. Regions and flash windows with the strongest correlations will be identified, and rough estimates of mean NO_x production per flash for these regions will be produced using mean NO_x/NO₂ ratios for the upper troposphere from the NASA GMI model. Progress will also be reported on the development of an algorithm to retrieve TROPOMI NO₂ column amounts specifically for lightning, modeled after the algorithm we have developed and applied for OMI data.