An evaluation of thermodynamics phases of clouds in NICAM using depolarization ratio

Abstract:

An evaluation of precipitation and clouds in a cloud system resolving model is an important issue using observations such as ground observations and satellite data. Data from the CALIPSO (Winker et al. 2003) and CloudSat (Stephens et al. 2002) satellites are available for analyzing the vertical structures of precipitating and non-precipitating clouds. Especially, the CALIPSO has a 532 nm cross polarization channel, which is used to calculate depolarization ratio. This parameter is useful for identifying particle types such as liquid, 2D, and 3D ice particles (Yoshida et al. 2010). We developed the depolarization ratio simulator based on the empirical formula in the Joint simulator (Hashino et al. 2013) using CALIPSO data. For liquid hydrometeors, the depolarization is given as a function of nadir angle (time of operation), temperature (above or sub freezing temperature), total attenuated backscattering, extinction between two consecutive layers, and order of liquid layers. For solid hydrometeors, the depolarization is given as a function of nadir angle, temperature, and total attenuated backscattering. The order of liquid layers is calculated by employing a simplified lidar mask. In this study, we will evaluate thermodynamics phases of clouds in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM, Satoh et al. 2008) using Joint simulator. Especially, we will investigate the super-cooled clouds and effects of microphysical processes on cloud fractions of the super-cooled clouds in NICAM.