Concentration gradients and growth/decay characteristics of the seasonal sea ice cover

摘要: The growth and decay characteristics of sea ice in the northern southern hemispheres are presented quantitatively by using brightness temperature data from Nimbus 5 Electrically Scanning Microwave Radiometer. areal extent >15% cover follows a basically symmetrical seasonal cycle hemisphere, ranging 8×106 km2 summer to 16×106 winter. In contrast hemisphere is asymmetrical, with longer periods than 4×106 20×106 At different longitudes occurrences maximum rates advance edge differ up 2 months, similarly for retreat. distribution rate change latitudinal position edge, as reference point 50% concentration line near ice-ocean boundary, quasi-Gaussian function peak at about 60 km/month standard deviation ±120 km/month. However, some large 940-km/month observed when movement tends be eastward or westward direction as, example, Weddell Sea. gradient has considerable variability, following Poisson peaks 0.89% per kilometer derived 3-day averages 0.62% monthly averages. During cycle, dominant consolidated behind advancing while during retreat accompanied massive reduction within pack. changes also shown have good correlation 271 K surface isotherms inferred climatological data.