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Observing U.S. Regional Variability in Lightning NO 2 Production Rates
Author(s) -
Lapierre Jeff L.,
Laughner Joshua L.,
Geddes Jeffrey A.,
Koshak William J.,
Cohen Ronald C.,
Pusede Sally E.
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd031362
Subject(s) - lightning (connector) , lightning detection , environmental science , troposphere , meteorology , climatology , atmospheric sciences , thunderstorm , geography , geology , physics , power (physics) , quantum mechanics
Abstract Lightning is a large and variable source of nitrogen oxides (NO x ≡ NO + NO 2 ) to the upper troposphere. Precise estimates of lightning NO x (LNO x ) production rates are needed to constrain tropospheric oxidation chemistry; however, controls over LNO x variability are poorly understood. Here, we describe an observational analysis of variability in LNO 2 with lightning type by exploiting U.S. regional differences in lightning characteristics in the Southeast, South Central, and North Central United States. We use satellite NO 2 measurements from the Ozone Monitoring Instrument with Berkeley High Resolution vertical column densities, a combined lightning data set derived from the Earth Networks Total Lightning Network and National Lightning Detection Network TM measurements, and hourly winds from the European Centre for Medium‐Range Weather Forecasts climate reanalysis data set (ERA5) over May–August 2014–2015. We find evidence that cloud‐to‐ground (CG) strokes produce a factor of 9–11 more NO 2 than intracloud (IC) strokes for storms with stroke rates of at least 2,800 strokes·cell −1 ·hr −1 . We show that regional differences in LNO 2 production rates are generally consistent with regional patterns CG and IC stroke frequency and stroke current density. A comparison of stroke‐based and flash‐based CG/IC LNO 2 estimates suggests that CG LNO 2 is potentially underestimated when derived with flash data due to the operational definition of CG lightning. We find that differences in peak current explain a large portion of CG/IC LNO 2 variability, but that other factors must also be important, including minimum stroke rate. Because IC and CG strokes produce NO x in distinct areas of the atmosphere, we test the sensitivity of our results against the atmospheric NO 2 vertical distribution assumed in the a priori profiles; we show that the relative CG to IC LNO 2 was generally insensitive to the assumed NO 2 vertical distribution.