Evaluation of lightning-induced tropospheric ozone enhancements observed by ozone lidar and simulated by WRF/Chem

Abstract

High spatial- and temporal-resolution ozone lidar profiles, in conjunction with ozonesonde and satellite observations, are well suited to characterize short-term ozone variations due to different physical and chemical processes, such as the impact of lightning-generated NO x (LNO x) on tropospheric ozone. This work presents the hourly variation of tropospheric-ozone profiles measured by an ozone lidar at the University of Alabama in Huntsville, on July 14, 18, and 27, 2011. These ozone lidar data are compared with two WRF/Chem simulations, one with lightning NO (LNO) emissions and the other without. On July 14, 2011, the ozone lidar observed an ozone laminar structure with elevated ozone concentrations of 65~80ppbv below 2km, low ozone (50~65) ppbv between 2 and 5km, and high ozone up to 165ppbv between 5 and 12km AGL. WRF/Chem simulations, in conjunction with backward trajectory analysis, suggest that lightning events occurring within upwind regions resulted in an ozone enhancement of 28ppbv at 7.5km AGL over Huntsville. On July 27, LNO emissions were transported to Huntsville from upwind and account for 75% of NO x and an 8.3ppbv of ozone enhancement at ~10km; the model overestimates ozone between 2.5 and 5km AGL.