Development of All-Sky Assimilation of Microwave Imager Radiance in the Korean Integrated Model

This study presents preliminary results from assimilation of Advanced Microwave Scanning Radiometer 2 (AMSR2) all-sky radiances within the Korean Integrated Model (KIM) forecasting system. In the observation pre-processing system, components have been added to support the all-sky approach: radiative transfer model calculations that consider KIM hydrometeors; estimation of observation error in cloud areas; additional quality control processes; superobbing. As a result, AMSR2 radiances are additionally used in regions with large cloud amounts such as the Inter-Tropical Convergence Zone (ITCZ), Pacific, and mid-latitude oceanic areas. KIM cycling experiments have been conducted to examine the impact of AMSR2 cloudy pixels. Short-range forecast field verification against other observations shows improvements in temperature, humidity, and wind variables in the middle and lower troposphere. In particular, humidity improved significantly by up to 2% in the Tropics.