First ISCCP Regional Experiment (FIRE) Atlantic Stratocumulus Transition Experiment (ASTEX) Colorado State University (CSU) Ceilometer Data (FIRE_AX_CSU_CEILOM)

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 basic understanding of the interaction of physical processes in determining life cycles 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, and higher space and time resolution cloud data.To-date, four intensive field-observation periods were planned and executed: 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 observationswith modeling studies to investigate the cloud properties and physical processes of the cloud system.The Belfort Laser Ceilometer was operated during FIRE ASTEX on Porto Santo, Madeira. It utilized a 20 watt near-infrared Gallium-Arsenide laser operating at a wavelength of 0.91 microns to detect cloud base height. It employed 1024 range gates which yield a vertical resolution of 25 feet up to a maximum range of 25,600 feet. The fields of view of the transmitter and receiver are approximately 1 degree.The ceilometer used a measured noise level to determine a count (-1,0,1) which is then summed for each gate. This histogram is the basic output from which the cloud base height is estimated.