First ISCCP Regional Experiment (FIRE) Atlantic Stratocumulus Transition Experiment (ASTEX) Colorado State University (CSU) PRT-6 Data

The First ISCCP Regional Experiments have been designed to improve data products and cloud/radiation parameterizations used in general circulation models (GCMs). Specifically, the goals of FIRE are (1) to seek the basicunderstanding of the interaction of physical processes in determining lifecycles of cirrus and marine stratocumulus systems and the radiative properties of these clouds during their life cycles and (2) to investigate the interrelationships between the ISCCP data, GCM parameterizations, andhigher space and time resolution cloud data.To-date, four intensive field-observation periods were planned andexecuted: a cirrus IFO (October 13 - November 2, 1986); a marine stratocumulus IFO off the southwestern coast of California (June 29 - July 20, 1987) a second cirrus IFO in southeastern Kansas (November 13 - December 7, 1991); and a second marine stratocumulus IFO in the eastern North Atlantic Ocean (June 1 - June 28, 1992). Each mission combined coordinated satellite, airborne, and surface observations with modeling studies to investigate the cloud properties and physical processes of the cloud system.The PRT-6 radiometer is a chopped bolometer which can passively senseinfrared targets within the spectral range of 2 to 20 microns. The radiometer is configured to accept optics with either a 2 or 20 degree field of view. The output is a voltage signal sampled at a frequency of 1/0.1 sec. The average of the sampled voltage was recorded every 10 seconds, which is nominally linear with respect to the incident radiant power.For the FIRE ASTEX deployment the instrument was configured with a field of view of 2 degrees and made use of an interference filter. This filter effectively limited the spectral bandpass to 885 to 945 inverse centimeters. Most of the measurements were made with the instrument pointing vertically upward, although for brief intervals zenith angles of 15, 30, 45, 60, and 75 degrees were also utilized.