Accession Number:

ADA190456

Title:

The Collection of Statistics on the Frequency of Cloud Cover Over North America.

Descriptive Note:

Annual letter rept. for FY 87,

Corporate Author:

WISCONSIN UNIV-MADISON SPACE SCIENCE AND ENGINEERING CENTER

Personal Author(s):

Report Date:

1987-01-01

Pagination or Media Count:

12.0

Abstract:

Statistics of cloud characteristics over North America have been calculated for the past two years. The frequency of cloud cover with the associated heights and infrared attenuation were charted using the CO2 channel radiometric data from the geostationary VISSR Atmospheric Sounder VAS. Cloud top pressure were determined from the ratio of VAS CO2 channel radiances in a radiative transfer equation formulation. Cloud emissivities were then calculated from infrared window channel observations. CO2 techniques derived height and emissivity assignments have been found to be reliable in all cloud types, including thin cirrus clouds where other techniques have been inconsistent. Observations since 1985 revealed that 25 to 35 of the United States was covered with thin clouds radiative attenuation was less than 95, 45 was covered with thick opaque clouds, and 20 to 30 had clear sky conditions. Geographical distribution of cloud cover shows a latitudinal dependence mainly over the Pacific Ocean. Moderate seasonal and diurnal changes were also found.

Subject Categories:

  • Meteorology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE