Arctic multiyear ice classification and summer ice cover using passive microwave satellite data
Arctic multiyear ice classification and summer ice cover using passive microwave satellite data
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DOI：
10.1029/jc095ic08p13411
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发表时间：
1990-08
影响因子：
--
通讯作者：
J. Comiso
中科院分区：
文献类型：
--
作者：
J. Comiso
研究了利用多光谱被动微波数据对北极多年海冰覆盖进行分类和监测的能力。对几个夏季极小期的海冰浓度图进行了分析，以获得在夏季存活的冰的估计。使用一种假设多年冰具有一定辐射率的算法，将结果与从次年冬季数据中得出的多年冰浓度进行比较。从冬季资料推断出的多年冰覆盖大约比夏季最小冰覆盖少25%到40%，这表明即使在海冰发射率最稳定的冬季，被动微波数据也可能只占多年冰覆盖总量的一小部分。在此期间，大约2×106 km2的差异比通过Fram海峡的平流的估计值大得多。就像在南极一样，北极的一些多年浮冰，特别是那些靠近夏季边缘冰带的浮冰，在随后的冬季似乎具有第一年冰或中间冰的特征。一种可能的机制是海水侵入雪-冰界面，这种情况经常发生在边缘冰带附近或雪荷载较大的地区。融冰和融池效应的空间变化也导致了多年冰微波发射率的复杂性。因此，多年冰资料应与以前的夏季冰资料结合起来研究，以获得对北极冰盖状况的更完整的描述。夏季北极浮冰的总面积和实际面积估计分别为8.4×106 km2和6.2×106 km2，并且在1979 - 1985年间表现出较小的年际变化，表明冰盖相对稳定。
The ability to classify and monitor Arctic multiyear sea ice cover using multispectral passive microwave data is studied. Sea ice concentration maps during several summer minima have been analyzed to obtain estimates of ice surviving the summer. The results are compared with multiyear ice concentrations derived from data the following winter, using an algorithm that assumes a certain emissivity for multiyear ice. The multiyear ice cover inferred from the winter data is approximately 25 to 40% less than the summer ice cover minimum, suggesting that even during winter when the emissivity of sea ice is most stable, passive microwave data may account for only a fraction of the total multiyear ice cover. The difference of about 2×106 km2 is considerably more than estimates of advection through Fram Strait during the intervening period. It appears that as in the Antarctic, some multiyear ice floes in the Arctic, especially those near the summer marginal ice zone, have first-year ice or intermediate signatures in the subsequent winter. A likely mechanism for this is the intrusion of seawater into the snow-ice interface, which often occurs near the marginal ice zone or in areas where snow load is heavy. Spatial variations in melt and melt ponding effects also contribute to the complexity of the microwave emissivity of multiyear ice. Hence the multiyear ice data should be studied in conjunction with the previous summer ice data to obtain a more complete characterization of the state of the Arctic ice cover. The total extent and actual areas of the summertime Arctic pack ice were estimated to be 8.4×106 km2 and 6.2×106 km2, respectively, and exhibit small interannual variability during the years 1979 through 1985, suggesting a relatively stable ice cover.