Cirrus Cloud Remote Sensing Program at FARS

High level cirrus clouds are believed to be important modulators of the radiation balance of the earth/atmosphere system, yet their effects on our potentially warming climate are poorly understood. Although satellites are well positioned to monitor global cloud cover, improvements in current multichannel radiance cloud algorithms to identify and categorize high level clouds are needed. In support of Project FIRE and a broader program of basic cloud research, passive and active remote sensing instrumentation at the University of Utah Facility for Atmospheric Remote Sensing (FARS) has been applied to the study of cirrus clouds since December 1986. At FARS we maintain a data collection schedule in support of NOAA satellite measurements to provide cloud-truth information, routinely using 0.1 Hz polarization (0.694 µm) lidar and coaligned narrow-beam infrared (9.5-11.5 µm) radiometer, various wideband radiometers, and all-sky photography. Derived data products are cloud top and base heights (and local sounding temperatures), cloud phase and composition information, and estimated visible cloud optical thickness and infrared emissivity. As of this time about 1600-hr of this sort of data have been collected at FARS, and more recent observation periods have also involved high-resolution, two-color (1.06 and 0.532 µm) polarization lidar and W-band (3.2 mm) polarimetric Doppler radar.