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A study of marine stratocumulus using lidar and other FIRE aircraft observationsThe National Center for Atmospheric Research (NCAR) airborne infrared lidar system (NAILS) used in the 1987 First ISCCP Regional Experiment (FIRE) off the coast of California is a 10.6 microns wavelength carbon dioxide lidar system constructed by Ron Schwiesow and co-workers at NCAR. The lidar is particularly well suited for detailed observations of cloud shapes; i.e., height of cloud top (when flying above cloud and looking down) and cloud base (when flying below cloud and looking up) along the flight path. A brief summary of the lidar design characteristics is given. The lidar height resolution of plus or minus 3 m allows for the distance between the aircraft and cloud edge to be determined with this accuracy; however, the duration of the emitted pulse is approximately 3 microseconds, which corresponds to a 500 m pulse length. Therefore, variations in backscatter intensities within the clouds can normally not be resolved. Hence the main parameter obtainable from the lidar is distance to cloud; in some cases the cloud depth can also be determined. During FIRE the lidar was operational on 7 of the 10 Electra flights, and data were taken when the distance between cloud and aircraft (minimum range) was at least 500 m. The lidar was usually operated at 8 Hz, which at a flight speed of 100 m s(-1) translates into a horizontal resolution of about 12 m. The backscatter as function of time (equivalent to distance) for each laser pulse is stored in digital form on magnetic tape. Currently, three independent variables are available to the investigators on the FIRE Electra data tapes: lidar range to cloud, strength of return (relative power), and pulse width of return, which is related to penetration depth.
Document ID
19910001198
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Jensen, Jorgen B. (National Center for Atmospheric Research Boulder, CO, United States)
Lenschow, Donald H. (National Center for Atmospheric Research Boulder, CO, United States)
Date Acquired
September 6, 2013
Publication Date
July 1, 1990
Publication Information
Publication: NASA, Langley Research Center, FIRE Science Results 1988
Subject Category
Meteorology And Climatology
Accession Number
91N10511
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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