Accession Number : ADA327353

Title :   Satellite Observations of Marine Stratus/Stratocumulus.

Descriptive Note : Final rept.,

Corporate Author : OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES

Personal Author(s) : Coakley, James A., Jr

PDF Url : ADA327353

Report Date : 14 JUN 1995

Pagination or Media Count : 29

Abstract : Work supported by this ONR Grant led to the stream lining of spatial coherence analysis software and allowed the application of the spatial coherence analysis to a large volume of satellite imagery data. The analyses were performed in order to obtain the properties of low level clouds and the cloud free ocean background. The work led to the findings that: (1) reflectivities of broken clouds at both 0.63 and 3.7 pm are smaller than those of nearby uniform clouds indicating that the broken clouds have substantially less liquid water than do their uniform counterparts and that photons are escaping through the sides of the broken clouds and being absorbed by the ocean surface. (2) The thin atmosphere approximation used to justify the split window technique for obtaining sea surface temperatures from satellite imagery data fails to give the sensitivity of the emitted radiances to variations in the atmospheric optical path that arise from changes in the scan angle of the imaging radiometer. (3) Substantial portions of low level marine stratocumulus are semitransparent at 11-pm. (4) As do fractional cloud cover and liquid water amount, droplet radius appears to vary from pixel to pixel at the scale available from conventional satellite imagery data (1 km). (5) Comparisons of cloud cover derived using the spatial coherence method applied to satellite imagery data for the Atlantic Stratocumulus Transition Experiment (ASTEX) with cloud cover predicted by forecast models indicated that the forecast models were unable to adequately predict low level clouds. The deficiency was thought to be due to the inability of the model to adequately predict the relative humidities in the upper levels of the boundary layer.

Descriptors :   *CLOUDS, *CLOUD COVER, *SATELLITE IMAGERY, COMPUTER PROGRAMS, SPATIAL DISTRIBUTION, OCEAN SURFACE, MODELS, COHERENCE, WEATHER FORECASTING, LOW LEVEL, RADIOMETERS, TELEMETERING DATA, REFLECTIVITY, SURFACE TEMPERATURE.

Subject Categories : Meteorology
      Cartography and Aerial Photography
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE