Characteristics of cloud microphysical properties observed at the Cloud Physical Observation System (CPOS) site in Korea

The Cloud Physics Observation Site (CPOS) site was established in 2004 over the mountainous area in the eastern part of Korea to collect cloud physics data on a long term basis. The instruments installed included a Micro Rain Radar (MRR), a Forward Scattering Spectrometer Probe (FSSP), a Microwave radiometer (MWR), and a disdrometer. This study mainly focuses on the bright band and raindrop size distribution (RDSD) characteristics of precipitating clouds measured at the CPOS site for the three year period of 2004-2006. As a comparison we also analyzed the MRR data measured at a western coastal site in Korea, Hae-Nam, HN. First we classified the vertical equivalent reflectivity factor profiles from MRR into three types, low level rain (Type 1), rain with a distinct bright band (Type 2), and convective rain (Type 3). It was found that the mountainous site (CPOS) had more proportion of Types 1 and 2 profiles while Type 3 covered 51% of the coastal site (HN) precipitation, suggesting the prevalence of orographically induced stratiform precipitation at the CPOS and convective precipitation at HN. Furthermore, the bright band appeared to be thicker but the sharpness of the band is weaker for the CPOS Type 2 profiles than those of HN. It was argued that the contrast was due to the dominant growth and melting of unrimed snow particles at HN and the prevailing rimmed ice crystals with the supercooled drops at the CPOS in stratiform precipitation. Preliminary analysis showed that on average the RDSD of HN is larger than those of the CPOS. The difference in RDSD was prominent for the diameter greater than 2.5 mm, where the RDSD of HN was definitely larger than those of the CPOS. As discussed above, these results might be due to the differences in geographical settings between the CPOS and HN; HN was generally affected by convective precipitation and the CPOS has more occurrence of straitform precipitation. Further analyses of the date from other instruments will be presented at the conference