An Overview of KMA’s Operational NWP Data Assimilation Systems

Currently, the Korea Meteorological Administration (KMA) is operating two global models. One is the Unified Model (UM) developed by the United Kingdom Met Office, and the other is the Korean Integrated Model (KIM), which was developed by the Korea Institute of Atmospheric Prediction Systems (KIAPS) during a 9-year project funded by KMA. The UM global model has been operation since 2010, and the KIM global model since April 2020. The plan is that KIM will be the sole operational global model of KMA after retirement of the UM at the end of 2022. In this chapter, we introduce the data assimilation systems used with the two global models, and with the limited area models that are nested inside the global UM. The UM global model uses a hybrid-4DVar data assimilation system, while the KIM global model uses a hybrid-4DEnVar system. UM-based 1.5 km local and very short range forecast models cycled with 3DVar are also being operated. KMA also runs another very short range forecasting system with a 5 km grid spacing named the Korea Local Analysis and Prediction System (KLAPS) which is also cycled with 3DVar.