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Incorporating Lightning Flash Data into the WRF-CMAQ Modeling System: Algorithms and Evaluations
Citation:
Kang, D., David-C Wong, R. Gilliam, K. Foley, S. Roselle, Jon Pleim, AND R. Mathur. Incorporating Lightning Flash Data into the WRF-CMAQ Modeling System: Algorithms and Evaluations. 16th CMAS Conference, Chapel Hill, North Carolina, October 23 - 25, 2017.
Impact/Purpose:
In this study, we implemented both lightning assimilation and LTNO production in the two-way coupled WRF-CMAQ (Community Multiscale Air Quality) modeling system. The lightning assimilation is implemented in the WRF model based on observed lightning flashes, and the same flash information is passed on to CMAQ to generate LTNO.
Description:
We describe the use of lightning flash data from the National Lightning Detection Network (NLDN) to constrain and improve the performance of coupled meteorology-chemistry models. We recently implemented a scheme in which lightning data is used to control the triggering of convective clouds via the Kain-Fritsch (KF) convective scheme to improve retrospective simulations of the Weather Research and Forecasting (WRF) model. Additionally, the same lightning flash data are passed on to the Community Multiscale Air Quality (CMAQ) model in the two-way coupled WRF-CMAQ modeling system to estimate lightning NO production. It is demonstrated that lightning assimilation improves prediction of near-surface meteorological variables, especially the timing, location, and amount of summertime rainfall. With more precise simulations of the meteorological fields and the inclusion of lightning-induced NO emissions, it is expected that surface air quality simulations would be significantly impacted. We systematically assess the impact of these two process improvements on predictions of meteorological and chemical fields through comparisons with measurements of surface pollutant concentrations and deposition amounts. A set of four model simulations is performed: (1) base case; (2) with lightning data assimilation in the KF scheme; (3) with lightning NO emissions; and (4) with both lightning data assimilation in the KF scheme and lightning NO emissions. The simulation results and comparisons with observations will be discussed
