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A Study of the Impact of Cirrus Clouds on High Altitude, Long Horizontal Path Laser Transmission

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Technical rept.

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The Geophysics Directorate of the USAF Phillips Laboratory is supporting efforts to estimate the environmental impacts on the proposed AirBorne Laser ABL system, a laser system being considered for theater missile defense. One of the environmental factors of particular concern is cirrus clouds which can be found at the proposed levels for the ABL system. Cirrus clouds can have spatial extents ranging from several tens of meters to several thousands of kilometers and are found at altitudes ranging from 4.0 to 20.0 kilometers. They are very persistent, and have a wide range of optical properties. Even cirrus clouds that have very low extinction coefficients, thus rendering them not visible for most viewing geometries, can have an effect on an Electro-Optic EO system if the cirrus optical path of the EO system is fairly long. Cirrus clouds with low extinction coefficients are difficult to remotely sense with either ground or space based systems. Therefore, many of the present cirrus cloud databases contain incomplete information about optically thin cirrus clouds. The problem of determining cirrus cloud physical and optical properties is compounded by the high altitude location of these clouds. Recently, a number of programs have been conducted to investigate the physical and optical properties of cirrus clouds because of their unique impact on the global climate. These databases provide information that can be applied to studies of the impacts of cirrus on EO systems operating at cirrus cloud altitude and above. ABL, Laser, Troposphere, Stratosphere, Transmission, Extinction, Optical depth, Subvisual cirrus, Thin cirrus, Opaque cirrus, Microphysical.

Subject Categories:

  • Meteorology
  • Lasers and Masers
  • Infrared Detection and Detectors

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