Differences in ice cloud microphysical properties between western and eastern tropical pacific regions derived from cloudsat and CALIPSO measurements

We revealed the difference in the ice cloud microphysical properties of high clouds between the western Pacific (WP) and eastern Pacific (EP) regions, based on satellite retrievals. The effective particle radius (r_e) was analyzed by using active sensors on board the CloudSat and CALIPSO satellites. We focused on ice clouds, defined as clouds with cloud top temperatures of less than 0°C. These ice clouds are classified into five types defined by the cloud optical thickness (COT). Mean cloud top heights of high cloud in WP were higher than those in EP by about 2km. The r_e of optically thin clouds (0 < COT < 0.3) showed weak temperature dependency over both regions. For optically thick clouds (3 < COT), r_e increases with temperature (T). In the WP, r_e at lower temperatures (T < -40°C) is larger than that in the EP, whereas in the EP, re at higher temperatures (T > -40°C) is larger than that in the WP. The difference in re may be caused by differences in moisture convergence and upward motion.