The NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) combines detailed, flash-specific measurements of lightning with both theoretical and empirical laboratory results to obtain estimates of lightning NOx production. Each LNOM dataset is based on measurements from a specific regional VHF Lightning Mapping Array (LMA), and on ground flash location, peak current, and stroke multiplicity data from the National Lightning Detection Network (NLDN). Both the LMA and NLDN data are used to determine the flash type (ground or cloud) of each flash occurring within an analysis cylinder. The LNOM analyzes the LMA sources to estimate the total channel length of each flash. It also produces the Segment Altitude Distribution (SAD) product by dicing up the lightning channel into 10-m segments, and then tallies those segments as a function of altitude. From all of the 10-m segments, the LNOM computes the vertical lightning NOx profile inside the analysis cylinder and the total NOx produced by each flash. A summation of the NOx profiles contributed to the analysis cylinder by each flash gives the final lightning NOx profile product for the analysis period studied (typically a 1 month profile). The LNOM NOx profiles include NOx from several non-return stroke lightning NOx production mechanisms. Users of LNOM data typically include regional air quality and global chemistry/climate modelers who need to better-parameterize lightning NOx sources. Rather than assigning an unrealistic fixed amount of NOx to ground and cloud flashes, the modeler can employ LNOM data to assign realistic (and statistical) NOx profiles to each flash.

Tags: earth science, atmosphere, atmospheric electricity, atmospheric phenomena, ngda, national geospatial data asset