Short Name:

First ISCCP Regional Experiment (FIRE) Cirrus Phase I Langley Research Center (LARC) Eight Inch Lidar

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 improve 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 observations with modeling studies to investigate the cloud properties and physical processes of the cloud systems.The Langley Research Center (LARC) Cloud Lidar is a dual-channel polarization sensitive lidar using a frequency doubled Nd: YAG laser as a linearly polarized transmitter and an eight inch Cassegrainian telescope as a receiver. Backscattered laser light collected by the receiver is collimated, directed through a half wave plate, and then passed through polarizing optics which decompose the signal into two components, one parallel and the other perpendicular to the polarization plane of the transmitted beam. Separate amplification and digitization paths are employed for each component, resulting in two arrays of back scatter data for each measured laser pulse. The LARC Cloud Lidar is designed for optimum cloud monitoring operations at altitudes between 3 km and 18 km. To prevent saturation of the detectors at lower altitudes, a gating circuit is used to delay the activation of the first dynode in the Photomultiplier (PMT). The PMT is brought to full sensitivity only after this delay time has elapsed.

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