Estimates of Lightning NOx Production from OMI NO2 Observations during DC3

A specialized retrieval algorithm for tropospheric column NO2 estimates from lightning was developed for the Deep Convective Clouds and Chemistry (DC3) field program, conducted during May and June 2012. The algorithm improves upon previous work we have performed for case studies in the Costa Rica/Panama region and over the continental United States. 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 NO2 (LNO2). The tropospheric background is computed from a combination of OMI climatology and output from simulations of NASA's Global Modeling Initiative (GMI) chemical transport model run with and without lightning. We first review the daily maps of the LNO2 product over the DC3 study period and link areas of LNO2 enhancements with specific regions of deep convection. We then select case study storms to estimate LNOx production based on a combination of the number of moles of LNO2 indicated by OMI, the flashes recorded by the National Lightning Detection Network and Lightning Mapping Arrays, and the NOx/NO2 ratio in the upper troposphere from the GMI model.