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Author Benner, T. C. ♦ Curry, J. A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ENVIRONMENTAL SCIENCES ♦ SOLAR RADIATION ♦ INSOLATION ♦ CLOUDS ♦ CLOUD COVER ♦ CLIMATES ♦ TROPICAL REGIONS ♦ ENVIRONMENTAL EFFECTS ♦ ALBEDO ♦ DISTRIBUTION FUNCTIONS ♦ FRACTALS ♦ ASPECT RATIO ♦ MORPHOLOGY ♦ DIMENSIONS ♦ ATMOSPHERIC PRECIPITATIONS ♦ REMOTE SENSING ♦ TEMPERATURE MONITORING
Abstract This study uses a number of data sets (Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator data, space shuttle photography, Radiation Measurement System data, aircraft data, and shipboard soundings) to investigate the characteristics of small tropical cumulus clouds and their impact on their environment. The goal is to uncover useful information with application to radiative transfer simulation and satellite remote sensing. In fields of small cumulus clouds, size distributions are found to decrease in number with increasing diameter according to a double power law relation, often with a clear break diameter. Fractal dimensions corresponding to the horizontal area and perimeter of the clouds are greater for the larger clouds than for the smaller clouds, with the same break diameter as the size distributions, meaning that the larger clouds have more ragged perimeters. These two results suggest a characteristic horizontal length scale dividing larger and smaller boundary layer cumuli. Spatial distributions show a clear tendency toward clustering. Smaller cumuli appear to grow upward more quickly with increasing horizontal size than do larger cumuli. Albedo is found to increase with greater cloud fraction and higher solar zenith angle. Even sparse fields of small cumulus cause significant shortwave forcing at the ocean surface. Simulation suggests that small cumulus may introduce significant errors into sea surface temperature retrievals and that such clouds can be difficult to remove with operational cloud-filtering schemes. Clouds smaller than about 1 km in diameter are not seen to precipitate. {copyright} 1998 American Geophysical Union
ISSN 01480227
Educational Use Research
Learning Resource Type Article
Publisher Date 1998-11-01
Publisher Place United States
Journal Journal of Geophysical Research
Volume Number 103
Issue Number D22


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