Asian Atmospheric Particulate Environment Change Studies (APEX) project and EarthCARE (Earth Cloud, Aerosols, and Radiation Experiment) proposal Validation team jointly conducted regional experiment in southwest Japan in March and April 2003. This experiment aims to understand the aerosol properties and their effects to the cloud system in east-Asia region, where various kinds of aerosols are transported in spring. For this purpose, chemical characteristics, physical properties and radiation characteristics of cloud and aerosols are measured from aircraft, surface, and satellites.

In this experiment, a W-band cloud profiling radar developed by Communications Research Laboratory and a UV Mie lidar developed by National Institute for Environmental Studies are installed on Gulfstream-2 aircraft. Nadir-looking measurements by both radar and lidar over cloud top height provide vertical cloud structure and cloud physical properties over broad area. Nine flights of Gulfstream-2 were performed in this experiment and radar and lidar data were obtained over 24 hours. Using algorithm of combining radar and lidar data, liquid water content will be inferred. This algorithm will be validated by in-situ measurement of cloud properties using other aircraft. This kind of validation is indispensable to development of algorithm for satellite borne cloud radar/lidar such as proposed EarthCARE. Following figure shows an example of radar reflectivity observed by the airborne cloud profiling radar.