Impacts of aerosol-radiation interaction on meteorological forecast over northern China by offline coupling the WRF-Chem simulated AOD into WRF: a case study during a heavy pollution event
Abstract
To facilitate the future inclusion of aerosol-radiation interactions in the regional operational Numerical Weather Prediction (NWP) system RMAPS-ST (adapted from WRF) at the Institute of Urban Meteorology (IUM), China Meteorological Administration (CMA), the impacts of aerosol-radiation interactions on the forecast of surface radiation and meteorological parameters during a heavy pollution event (December 6th -10th, 2015) over northern China were investigated. The aerosol information was simulated by RMAPS-Chem (adapted from WRF-Chem) and then offline-coupled into RRTMG radiation scheme of WRF to enable the aerosol-radiation feedback in the forecast. Comparisons with in-situ and MODIS, AERONET, and CALIPSO satellite observations showed that the model could reproduce and spatial and vertical distribution as well as the temporal variation the of polluted episode. Further comparison of PM2.5 with in-situ observation showed WRF-Chem reasonably captured the PM2.5 field in terms of spatial distribution and magnitude. Forecasts with/without the aerosol information were conducted further, and the differences of surface radiation, energy budget, and meteorological parameters were evaluated against surface and sounding observations. The offline-coupling simulation (with aerosol-radiation interaction active) showed a remarkable decrease of downward shortwave (SW) radiation reaching surface, thus helping to reduce the overestimated SW radiation during daytime. The simulated surface radiation budget was also improved, with the biases of net surface radiation decreased by 85.3%, 50.0%, 35.4%, and 44.1% during daytime at Beijing, Tianjin, Taiyuan and Jinan respectively. In addition, the cooling of 2-m temperature (~0.40 °C) and the decrease of horizontal wind speed near surface (~0.08 m s-1) caused by the aerosol-radiation interaction over northern China helped to reduce the bias by ~73.9% and ~7.8% respectively, particularly during daytime. These results demonstrated the influence of aerosol-radiation interactions on the improvement of predictive accuracy and the potential prospects to offline couple near-real-time aerosol information in regional RMAPS-ST NWP in northern China.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.A15F1709Y