Ground-Based Multiple Remote Sensor Studies of Clouds at the Cloud and Radiation Testbed

Clouds play a critical role in the energy balance of the climate system. The impact of clouds on climate system depends on a number of microphysical and macrophysical properties, including cloud water/ice content, altitude, etc. There is a considerable interest in obtaining more accurate and reliable information on clouds to improve the simulation of cloud process in general circulation models (GCMs) and to better understand our climate. A variety of lidar techniques play a very important role in the remote characterization of clouds, but optical methods cannot penetrate optically thick clouds. To get more complete information of clouds, it is necessary to combine lidar with other remote sensors such as radar and passive radiometers. Many algorithms are currently under development for this purpose.

The Department of Energy Atmospheric Radiation Measurement (ARM) Program Cloud and Radiation Testbed (CART) is one of the foremost integrated multiple remote sensor center in the world. We are developing an algorithm to combine lidar, radar, microwave radiometer, and infrared radiometer measurements at CART for cloud study. Cloud-base height, cloud vertical extent, cloud optical thickness, cloud water/ice content, and effective size can be obtained in this algorithm. This study will present this algorithm and results from at least one full year of CART measurements.