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The Korean Integrated Model (KIM) forecast system, based on a hybrid four‐dimensional ensemble‐variational method, was extended to assimilate Horizontal Line‐Of‐Sight (HLOS) wind observations from the Atmospheric Laser Doppler Instrument (ALADIN) on board the Atmospheric Dynamic Mission Aeolus satellite. In a global cycling experiment, assimilation of Aeolus HLOS wind observations led to reductions in the average root‐mean‐square error of 0.8 and 0.5% for the zonal and meridional wind analyses when compared against European Center for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analyses. Even though the observed variable is wind, there was also an overall beneficial impact on analyses of the mass variables. In the Southern Hemisphere (SH), the reduced analysis errors led to forecast skill improvements out to 72 h. In contrast, in the Northern Hemisphere (NH) there was relatively little reduction of analysis errors, but wind forecasts were nevertheless improved, and these positive impacts lasted longer – out to 120 h rather than 72 h. Experiments suggest that the relatively poor long‐range performance in the SH high latitudes was due to problems with the mass increments derived from Aeolus wind increments via the ensemble‐based part of the hybrid background error covariance (B), which eventually led to adverse effects on the wind variables as forecasts progressed in the SH. This study shows that it is necessary to estimate the ensemble B in the Antarctic region with its high elevation more accurately in order to effectively use the Aeolus observation information. [ABSTRACT FROM AUTHOR]

ABSTRACT Temporal trends and spatial distributions of visibility measured by the human eye over 60 stations in Korea between 1980 and 2000 are analyzed and discussed. Generally, visibility is lowest [...]

All-sky microwave radiance assimilation system has been developed in the Korean Integrated Model (KIM) analysis system. Initially, RTTOV-SCATT (version 11.3; Bauer et al., 2006; Geer et al., 2014) modules were implemented to assimilate the Microwave Humidity Sounder (MHS), Advanced Technology Microwave Sounder (ATMS), Sondeur Atmosphérique du Profil d'Humidité Intertropicale par Radiométrie (SAPHIR) and FY-3C Microwave Humidity Sounder-2 (MWHS) 183 GHz channels over ocean. A system development methodology for assimilating cloud and precipitation-affected satellite radiances has been developed in accordance with the ECMWF approach (Geer et al., 2014). There is no cloud or precipitation control variable, but in the minimization, cloud and precipitation are diagnosed from the dynamical and humidity fields every time-step including the first. In this study, the clear-sky and all-sky contributions to the assimilation of MHS are separated. The clear-sky assimilation shows the significant forecast benefits, but the all-sky assimilation is testing. Cloud and precipitation parameters are not directly assimilated in our system, but only temperature and humidity profiles are improved in the all-sky assimilation. [ABSTRACT FROM AUTHOR]