Comparative studies of climate sea ice data from SSM/I and AMSR-E

Historical satellite data reveal that among the most remarkable manifestations of changes in the polar regions are the relatively rapid decline of 10 %/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 those from the SSM/I data during periods of overlap. There are however significant differences associated with the significantly larger field-of-view of SSM/I compared with the AMSR-E. The ice area from the two sensors are basically consistent but the ice extent from SSM/I is usually higher than that of AMSR-E on account of the larger footprint from the former and associated side-lobe effects. The results of our analysis shows that AMSR-E provides improved accuracy for both variables and a bias in the values derived from SSM/I data. A method for overcoming this bias and a procedure for using AMSR-E data together with historical passive microwave data for enhancing the quality of the time series of sea ice data set and for improving the accuracy of estimates of trends will be presented.