Summary
Antarctic coastal polynyas are important areas of high sea ice production and dense water formation, and thus their detection including an estimate of thin ice thickness is essential. We propose an algorithm that estimates thin ice thickness and detects fast ice using SSM/I data in the Antarctic Ocean. Detection and estimation of sea ice thicknesses of <0.2 m are based on the SSM/! PR85 and PR37 through a comparison with sea ice thicknesses estimated from the A VHRR data. Exclusion of the data affected by atmospheric water vapor is discussed. We also detect fast ice (ice shelves, glacier tongues, icebergs, and landfast ice) by using the relationship between the 85-GHz vertical and horizontal brightness temperatures. This algorithm clearly distinguishes fast ice from thin ice in coastal areas where both coexist. The probability that the algorithm correctly distinguishes thin ice from thick ice and from fast ice is -95 %, relative to the ice thicknesses estimated from A VHRR. Although the standard deviation of the difference between the thin ice thicknesses estimated from the SSM/I algorithm and A VHRR is -0.05 m and thus not small, the estimated ice thicknesses from the microwave algorithm have no biases and the accuracies are independent of region and season.