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Adaptation of World Wide Lightning Location Network Observations for Lightning Assimilation and Lightning NO in the WRF-CMAQ Modeling System
Citation:
Kang, D., G. Sarwar, C. Hogrefe, D. Wong, AND R. Mathur. Adaptation of World Wide Lightning Location Network Observations for Lightning Assimilation and Lightning NO in the WRF-CMAQ Modeling System. AMS 2021, Morrisville, NC, January 10 - 14, 2021.
Impact/Purpose:
Lightning is one of the major natural sources to produce nitrogen oxides (NOX) which contribute to the tropospheric ozone (O3) formation and other air quality related processes. It is important to incorporate the most up-to-date science and observational data for lightning assimilation and lightning NOx productions in time and space in air quality models. Lightning flash data used in air quality models can be acquired from different observational lightning networks with varying accuracy, geographical coverage, and cost. The objective of this research is to evaluate lightning flash data from two commonly available lightning observation networks and to adapt the flash data based on cost and geographical coverage.
Description:
In the Weather Research and Forecasting (WRF) and Community Multiscale Air Qualtiy (CMAQ) modeling system for air quality predictions, observed lightning flash information can be assimilated to reduce errors associated with convective rainfall and other convection-related meteorological variables, and provide estimates of lightning nitrogen oxide (LNO) as one of the sources of natural NO emissions. Lightning flash data from National Lightning Detection Network (NLDN) over the contiguous United States and from the World Wide Lightning Location Network (WWLLN) over the globe were acquired for the 2016-2018 period. Application of these two data sources over the contiguous United States to model simulations has produced varying effects in time and space resulting from differing detection efficiencies with the two networks especially during summer months over land (versus over ocean). However, the lightning flash density differences between the two networks have shown persistent monthly patterns over geographical regions (e.g. land versus ocean). Since the NLDN data is considered to have higher accuracy (lightning detection with >95% efficiency), we develop scaling factors for the WWLLN flash data based on the ratios to the NDLN flash data over time (months of year) and space. In this exercise, model sensitivity simulations are performed using the original data sets (both NLDN and WWLLN) as well as the scaled WWLLN flash data for lightning assimilation and LNO production over the contiguous United States. Since WWLLN has global coverage, initial tests are also performed with the hemispheric CMAQ (HCMAQ) to provide LNO emissions using the original and scaled WWLLN flash data. The lightning assimilation and LNO effects based on the 2016 WRF-CMAQ modeling platform are assessed against observations from surface monitoring networks as well as aloft measurements.
