Optimized regional and interannual variability of lightning in a global chemical transport model constrained by LIS/OTD satellite data

• Published in: Journal of Geophysical Research: Atmospheres 2012-10, Vol.117 (D20), p.n/a
• Main Authors: Murray, Lee T., Jacob, Daniel J., Logan, Jennifer A., Hudman, Rynda C., Koshak, William J.
• Format: Article
• Language: English
• Subjects: Atmospheric sciences; Chemical transport; Earth sciences; Earth, ocean, space; El Nino; El Niño; Exact sciences and technology; Geophysics; interannual variability; Lightning; Lightning Imaging Sensor; Nitrogen dioxide; Nitrogen oxides; NOx; Ozone; Photochemicals; Troposphere
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2012JD017934

Nitrogen oxides (NOx ≡ NO + NO2) produced by lightning make a major contribution to the global production of tropospheric ozone and OH. Lightning distributions inferred from standard convective parameterizations in global chemical transport models (CTMs) fail to reproduce observations from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) satellite instruments. We present an optimal regional scaling algorithm for CTMs to fit the lightning NOxsource to the satellite lightning data in a way that preserves the coupling to deep convective transport. We show that applying monthly scaling factors over ∼37 regions globally significantly improves the tropical ozone simulation in the GEOS‐Chem CTM as compared to a simulation unconstrained by the satellite data and performs equally well to a simulation with local scaling. The coarse regional scaling preserves sufficient statistics in the satellite data to constrain the interannual variability (IAV) of lightning. After processing the LIS data to remove their diurnal sampling bias, we construct a monthly time series of lightning flash rates for 1998–2010 and 35°S–35°N. We find a correlation of IAV in total tropical lightning with El Niño but not with the solar cycle or the quasi‐biennial oscillation. The global lightning NOxsource ± IAV standard deviation in GEOS‐Chem is 6.0 ± 0.5 Tg N yr−1, compared to 5.5 ± 0.8 Tg N yr−1 for the biomass burning source. Lightning NOx could have a large influence on the IAV of tropospheric ozone because it is released in the upper troposphere where ozone production is most efficient. Key Points Regional scaling may be used to constrain IAV in lightning to satellite in model Tropical lightning correlates to ENSO activity over 1998‐2010, not solar cycle IAV in lightning NOx emissions is comparable to that from biomass burning