Estimates of lightning NO_x production per flash from OMI NO₂ and lightning observations

A specialized retrieval algorithm for estimates of tropospheric column NO_x due to lightning was developed for the Deep Convective Clouds and Chemistry (DC3) field program, conducted during May and June 2012, using NO₂ retrievals from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite, which provides once-per-day data from an overpass at ~1:30 PM LST. Two forms of the algorithm have been developed. The first is for active or recently active storms and the second is for relatively clear sky situations. Estimates of stratospheric and tropospheric background NO₂ columns are subtracted from the OMI total column observations and an air mass factor representative of a convective outflow regime was used to convert the residual to vertical columns of lightning NO_x (LNO_x). Four case study storms observed in DC3 were selected to estimate LNO_x production per flash based on a combination of the number of moles of LNO_x indicated by OMI and the contributing flashes recorded by the National Lightning Detection Network (NLDN) and Lightning Mapping Arrays (LMAs). Two cases involved OMI observations over active or very recently active lightning-producing storms. Another two cases involved LNO_x observed in relatively clear skies downwind of storms in the DC3 intensive study regions.