Plans for the evaluation of the KIAPS LETKF-based radar reflectiviity DA system

   The renewed KIAPS (Korea Institute of Atmospheric Prediction Systems) aims at developing a unified framework for seamless prediction from the very short range (~6 hours) to the extended medium range (~30 days), including coupling to various Earth system components, such as the land surface, oceans, and sea ice. For very short range forecasts, KIAPS is currently developing a high-resolution (1-5km) model targeting storm-scale high-impact weather over East Asia, centered on the Korean peninsula. In order to start developing methods for assimilating Korean radar reflectivity observations, we have developed a “testbed” system based on a high-resolution, limited-area version of WRF, configured by the Korea Meteorological Administration (KMA) to use the same physics packages as the Korean Integrated Model (KIM) global model. The data assimilation (DA) system is based on the Local Ensemble Transform Kalman Filter (LETKF), and currently only includes support for assimilation of 3D synthesis data derived from the radar reflectivity observation.
   In order to get reasonable ensemble analysis fields at the convective scale through the LETKF-based radar DA system, we have been evaluating and tuning the reflectivity assimilation method. In order to improve the analysis of synoptic scales, we are now also adding support for the assimilation of conventional observations (Sonde, Surface, Aircraft, etc.). To allow this, the KIM Package for Observation Processing (KPOP), which has so far only been able to use background fields from the KIM global model, is being extended to support use WRF limited-area background fields. When this work is completed, the LETKF system will be extended to assimilate the conventional observations provided by KPOP in addition to radar reflectivity observations. We will then continue evaluation and develop a full cycling system. The final goal will then be to replace WRF with the new high-resolution KIM model.