Impacts of Updated Physics Parameterizations on the Short-Range Weather Forecast System of the Korea Air Force

The weather prediction model system of Korea Air Force (KAF), based on the Weather Research and Forecasting (WRF) model, has been operated since 2007. This study incorporates recent physics parameterizations into the KAF-WRF system and evaluates their impacts on the performance of the system in simulating winter precipitation, fog, and low-level cloud events, as well as a real-time winter precipitation forecast during 1-month. Notably, the new physics suite simulates significantly reduced precipitation over mountainous regions, demonstrating greater agreement with actual observations for the winter precipitation case. The new physics suite considerably reduces cloud ice mixing ratios across all atmospheric layers while increasing cloud water and snow mixing ratios in the lower and upper layers, respectively. Higher cloud water mixing ratios in the new physics suite, compared to its old counterpart, result in simulations of greater amounts of low-level clouds and broader regions of fog. Additional sensitivity experiments indicate that the revised WRF Double-Moment 6-class (WDM6) scheme is primarily responsible for the simulation of increased cloud water and decreased cloud ice mixing ratios. Meanwhile, the real-time winter precipitation simulation conducted for January 2023, a period marked by significant temperature fluctuations and unusually heavy rainfall, reveals that the new physics suite enhances the ability of the KAF-WRF system to predict heavy precipitation events while maintaining adequate performance for light precipitation events. Overall, these findings suggest that the KAF-WRF system equipped with the new physics suite demonstrates better predictive capability for winter weather phenomena.