WRF-GC v2.0: online two-way coupling of WRF and GEOS-Chem for regional modeling of air quality-meteorology interactions

Abstract:

We developed the WRF-GC model, an online coupling of the Weather Research and Forecasting (WRF) meteorological model and the GEOS-Chem chemical transport model. The coupling structure of WRF-GC allows the two parent models to be updated independently and to run in the MPI-based, massively parallel architecture. WRF-GC v2.0 incorporated the aerosol-radiation (AR) and aerosol-cloud (AC) feedbacks to meteorology, as well as the nested-domain capability, to simulate the interactions between meteorology and air quality at high resolution. We conducted a series of test simulations with different combinations of AR and AC interactions using WRF-GC v2.0 to evaluate the performance of aerosol and cloud optical properties and impacts on air quality. The simulation including ACR interactions well reproduced the day-to-day variability of the aerosol optical depth (AOD) with correlation coefficients from 0.56 to 0.85 compared with the AERONET observations during January, 2015. The simulated July domain-average liquid cloud effective radius and optical depth were 10.5±2.4 μm and 11.8±8.5, respectively, in good agreement with Suomi-NPP VIIRS observations (13.9±2.5 μm and 18.4±7.2) in 2016. Including the ACR interactions also improved the model’s performance in reproducing the spatiotemporal variations of observed surface ozone concentrations over 581 sites in China in summer. In Beijing-Tianjin-Hebei region, the mean bias of simulated ozone decreased by 19% due to the ACR interactions. The development of the ACR interactions in WRF-GC enables the model to be a more effective tool for air quality research.