The polar sea ice cover from aqua/AMSR-E

Abstract

Historical satellite data reveal that among the most remarkable manifestations of changes in the polar regions are the relatively rapid decline of 9 %/decade in the Arctic perennial ice cover and the 7%/decade retreat in the Bellingshaussen/Amundsen Seas ice cover in the Antarctic. The launch of the Advanced Multichannel Scanning Radiometer (AMSR-E) on board the EOS-Aqua satellite in 2002 has enabled the study the polar ice cover in greater detail and the evaluation of the accuracy and consistency of historical satellite data. The AMSR-E system has higher resolution and larger spectral range thereby providing ability to better assess the spatial distribution of different ice types in the marginal ice zones, the sizes and characteristics of sensible and latent heat polynyas, and the extent of ridging and divergence within the ice pack. Comparative analysis reveals that the sea ice data derived from AMSR-E are coherent and consistent with Moderate Resolution Imaging Spectroradiometer (MODIS) data on board the same satellite, especially when the 5-km resolution 89 GHz data are used. During the periods of overlapping coverage, the AMSR-E data are also shown to provide basically the same spatial and temporal variability as those from the Special Scanning Microwave Imager (SSM/I) which has been the key source of sea ice data since 1987. Quantitative comparative studies using AMSR-E and SSM/I data also reveal a clear indication of the advantage of the former in consistently identifying the 10-15% ice edge and in quantifying the regional and global sea ice extents. This is reflected in the calculation for the trend in ice extent when AMSR-E data is used instead of SSM/I data. However, the difference is within error and the estimate for the trend in ice area is in good agreement.