Dynamics and Physics Updates in the KIM4.0 and Future Upgrade Plans

The Korean Integrated Model (KIM) is the operational global Numerical Weather Prediction (NWP) system developed by the Korea Institute of Atmospheric Prediction Systems (KIAPS). Since its operational deployment in 2020, KIM has undergone numerous enhancements aimed at reducing global bias and improving forecast skill. Recently, KIAPS introduced KIM version 4.0, an 8-km horizontal resolution model, featuring several advancements such as the revised scale-aware parameters in the KSAS convection scheme. A comprehensive year-round performance evaluation demonstrated significant reductions in global errors, particularly evident in mid-latitude regions especially during the winter season. At the same time, high-impact weather predictions such as heavy rain fall, heatwave and typhoon, showed much refined prediction performance, which allows for more reliable support for forecasters during extreme weather events over the Korean Peninsula. Efforts are currently focused on preparing the next version, with an emphasis on physics modifications to further alleviate global bias. A new diagnostic cloud scheme is under evaluation to replace the existing prognostic scheme, enhancing consistency in cloud and hydrometeors simulations, which is a crucial step towards more effectively addressing persistent global biases. Additionally, adjustments in the global hydrometeor structures impacting radiation response have been made through sub-grid hydrometeors modifications in the convection parameterization scheme, alongside phase conversion updates in the WSM5 microphysics scheme. Enhanced vertical wind structures are being explored via improvements in sub-grid orography. This presentation discusses the sensitivities and major impacts of these modifications. It also introduces ongoing efforts to develop Korea’s next-generation NWP systems at KIAPS, providing insights into currents challenges and future plans.