Sensitivity of Tropical Tropospheric Composition and radiative forcing to Lightning NOx Production and ENSO
Thursday, 18 December 2014
We investigate the sensitivity of tropical tropospheric composition during the September-November (SON) 2006 and 2007 time periods to the phase of El Niño-Southern Oscillation (ENSO) and to variations in lightning-NO production (LNOx) per flash using version 5 of NASA-Goddard Chemistry and Climate Model (CCM) run in the “replay mode” utilizing MERRA reanalysis data to constrain model dynamics. Model output from CCM runs with varying amounts of LNOx will be compared to MOPITT, AIRS, TES, and MLS CO; OMI NO2; and TES, OMI, OMI/MLS, and SHADOZ ozone. We will focus on how well each of the satellite products and CCM capture ENSO-driven variations in CO and ozone between the SON 2006 and SON 2007 time periods in the lower-, middle-, and upper-troposphere. We will also examine the sensitivity of NOy, NOx, NO2/NO, OH, HO2/OH, and O3 to LNOx as well as the implications on overall atmospheric radiative forcing (defined herein as the net flux imbalance at the tropopause). We will show that halving (doubling) LNOx production from 250 moles per flash changes the mean tropical downward radiative flux at 163 hPa due only to ozone attributable to lightning by -43% (+63%).