Publication Date:
2016-01-30
Description:
The reported range for global production of nitrogen oxides (NO x =NO+NO 2 ) by lightning remains large ( e . g ., 32 to 664 moles NO x flash -1 ), despite incorporating results from over thirty individual laboratory, theoretical, and field studies since the 1970s. Airborne and ground-based observations from the Deep Convective Clouds & Chemistry (DC3) experiment in May and June 2012 provide a new data set for calculating moles of NO x produced per lightning flash, P(NO x ) , in thunderstorms over the United States Great Plains. This analysis utilizes a combination of in-situ observations of storm inflow and outflow from three instrumented aircraft, three-dimensional spatial information from ground-based radars and satellite observations, and spatial and temporal information for intra-cloud and cloud-to-ground lightning flashes from ground-based lightning mapping arrays. Evaluation of two analysis methods ( e.g ., a volume-based and a flux-based approach) for converting enhancements in lightning-produced NO x from volume-based mixing ratios to moles NO x flash -1 suggests that both methods equally approximate P(NO x ) for storms with elongated anvils while the volume-based approach better approximates P(NO x ) for storms with circular-shaped anvils. Results from the more robust volume-based approach for three storms sampled over Oklahoma and Colorado during DC3 suggest a range of 142 to 291 (average of 194) moles NO x flash -1 (or 117 – 332 moles NO x flash -1 including uncertainties). Although not vastly different from the previously reported range for storms occurring in the Great Plains ( e . g ., 21 – 465 moles NO x flash -1 ), results from this analysis of DC3 storms offer more constrained upper and lower limits for P(NO x ) in this geographical region.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics