Accession Number : ADP007264

Title :   Variations of Extent, Area, and Open Water of the Polar Sea Ice Covers: 1978-1987,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER

Personal Author(s) : Gloersen, Per ; Campbell, William J.

Report Date : MAR 1992

Pagination or Media Count : 7

Abstract : The Scanning Multichannel microwave Radiometer (SMMR) which operated onboard the Nimbus-7 satellite from October 1978 to August 1987 obtained sequential synoptic observations of the entire Arctic and Antarctic sea ice covers every 2 days through the clouds during night and day. It is a unique almost decade-long data set of the large-scale behavior of sea ice on earth. Ibis paper presents the results of an analysis of SMMR observations of the Arctic, Antarctic, and global sea ice area, extent, and open water within the ice pack. These data are corrected for instrumental drift and errors due to variations in the ecliptic angle. Also presented is an analysis based on a combination of Fourier and ordinary least-squares regression techniques which yields their interannual variations and trends. In the power spectra of the Arctic and Antarctic sea ice areas and extents, the largest peaks are the dominant annual cycles, the second and third harmonics which are distinct, and the fourth and fifth which are identifiable. In order to remove the seasonal cycle, the first five harmonics are subtracted from the area and extent data, obtaining the residuals from which the trends are determined. During this 9-year period, the Arctic ice cover has negative trends of 1.9 +/- 1.3% for the extent and 1.6 +/- 1.6% for the area, with confidence levels of 95% as defined by the two-sigma criterion.

Descriptors :   *ICE MECHANICS, *OPEN WATER, *SATELLITE PHOTOGRAPHY, CLOUDS, CYCLES, DRIFT, GLOBAL, HARMONICS, MICROWAVES, OCEANS, POWER SPECTRA, RESIDUALS, SCALE, SCANNING, SEA ICE, VARIATIONS, WATER, ENVIRONMENTAL IMPACT, GREENHOUSE EFFECT.

Subject Categories : Snow, Ice and Permafrost
      Cartography and Aerial Photography
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE