A method to estimate subpixel-scale coastal polynyas with satellite passive microwave data

摘要: The importance of Antarctic coastal polynyas for heat exchange between ocean and atmosphere, high ice production, thus, with the resultant brine rejection, a large amount bottom water is widely recognized. To obtain full understanding their influence, continuous measurement even small necessary. Only passive microwave sensors, global coverage ability to penetrate cloud cover, can provide this information. However, because coarse resolution, special method estimate area subpixel-scale has been developed. It uses 85- 37-GHz data successively in order take advantage higher resolution at 85 GHz while compensating its sensitivity atmospheric effects data. This based on simulating images polynya events by convolving an assumed brightness temperature distribution satellite antenna pattern. These are compared measured iteratively modified until best agreement found. Application synthetic produces maximum error 200 km2 but mean 80 km2. shows distinct improvement over more traditional, i.e., concentration, methods. Analysis coincident infrared indicate that thickness up 0.06 m included estimated open area. Area time series derived near Halley Bay show day-to-day changes from 50 450 during austral spring. Interpretation these results terms wind forcing growth aided comparison one-dimensional model development.