Airborne quantification of upper tropospheric NOx production from lightning in deep convective storms over the United States Great Plains

The reported range for global production of nitrogen oxides ( NOx = NO + NO2) by lightningremains large (e.g., 32 to 664 mol NOx flash−1), despite incorporating results from over 30 individual laboratory, theoretical, and field studies since the 1970s. Airborne and ground-based observations from the Deep ConvectiveClouds and Chemistry experiment in May and June 2012 provide a new data set for calculating moles of NOxproduced per lightning flash, P( NOx), in thunderstormsover the United States Great Plains. This analysis utilizes a combination of in situ observations of storminflow and outflow from three instrumented aircraft, three-dimensional spatial information from ground-based radars and satellite observations, and spatial and temporal information for intracloud and cloud-to-ground lightning flashesfrom ground-based lightningmapping arrays. Evaluation of two analysis methods (e.g., a volume-based approach and a flux-based approach) for converting enhancements in lightning-produced NOxfrom volume-based mixing ratios to moles NOx flash−1 suggests that both methods equally approximate P( NOx) for stormswith elongated anvils, while the volume-based approach better approximates P( NOx) for stormswith circular-shaped anvils. Results from the more robust volume-based approach for three stormssampled over Oklahoma and Colorado during DC3 suggest a range of 142 to 291 (average of 194) moles NOx flash−1 (or 117–332 mol NOx flash−1 including uncertainties). Although not vastly different from the previously reported range for stormsoccurring in the Great Plains (e.g., 21–465 mol NOx flash−1), results from this analysis of DC3 stormsoffer more constrained upper and lower limits for P( NOx) in this geographical region.