Simulation of Ozone during Lightning Event in pre-Monsoon Season using WRF-Chem over India

Abstract:

In this study, WRF-Chem model has been used to simulate lightning temporal and spatial distributions before, during, and after thunderstorm during pre-monsoon period of 2009 over India. The functional relationship between thunderstorm wind speed and lightning frequency in the WRF-Chem model is also forecasted. The study domain consist of spatial resolution of 9 km, centered at 23^o N, 83^o E, covering most of the north-east part of India and some part of Bay of Bengal. The simulation has been run for 16^th May to 25^th May 2009 with/without lightning module. The first three days were taken as spin-up time. This study utilizes Emissions Database for Global Atmospheric Research (EDGAR) HTAP-2010, Fire Inventory from NCAR (FINN) and Model of Emissions of Gases and Aerosols from Nature (MEGAN) for anthropogenic, fire and biogenic emissions. The aerosol model chosen is Modal Aerosol Dynamic Model/Secondary Organic Aerosol Module (MADE-SORGAM). The model is integrated every one hour. The simulation outputs reveal that the surface concentration of NOx is found to be increased significantly after the lightning event. The magnitude of NOx and ozone is much higher with lightning module than without lightning module for higher affected areas. It is observed that surface ozone concentration is also changing with NOx concentration and there is a good correlation between the model simulated NOx and O₃ against satellite observations of OMI and TOMS ozone retrievals. The bias correction shows that model was able to successfully simulate high and low lightning dominant regions in terms of ozone concentrations.