基于CryoSat-2卫星测高数据的北极海冰体积估算方法

近30年来，北极海冰正发生着剧烈的变化。海冰体积是量化海冰变化的重要指标之一。本文以2015年CryoSat-2卫星测高数据和OSI SAF海冰类型产品为基础。提取了浮冰出水高度、积雪深度、海冰密集度、海冰类型等属性信息，通过数据内插、投影变换、栅格转换、空间重采样等工作将海冰属性信息统一为25 km×25 km分辨率的栅格数据集。根据流体静力学平衡原理，逐个估算栅格像元对应的海冰厚度值，将其与对应的海冰面积相乘，估算了北极海冰密集度大于75%海域的海冰体积，并分析了海冰厚度和体积的月变化和季节变化特征。用NASA IceBridge海冰厚度产品对反演的海冰厚度进行验证。结果表明二者相关系数为0.72，有较高的一致性。北极海冰平均厚度春季最大，夏季最小，分别约为2.99 m和1.77 m，最厚的海冰集中在格陵兰沿岸北部和埃尔斯米尔半岛以北海域。多年冰平均厚度大于一年冰。冬季海冰体积最大，约为23.30×103 km3，经过夏季的融化，减少了近70%。一年冰体积季节波动较大，而多年冰体积相对稳定，季节变化不明显。

Arctic sea ice volume estimation method based on CryoSat-2 Satellite altimeter data

In the last 30 years, the Arctic sea ice is undergoing drastic changes. Sea ice volume is one of the important indicators to quantify the change of sea ice. This paper according to the CryoSat-2 data and OSI SAF sea ice type data in Arctic in 2015. We extracted freeboard, snow depth, sea ice concentration and ice type, and obtained the raster data set in 25 km×25 km spatial resolution through data reprocessing including interpolation, projection transformation, raster conversion, spatial resampling and so on. According to the hydrostatic equilibrium principle calculated the sea ice thickness value in every pixel, multiply ice area in the corresponding pixels thus estimated the sea ice volume of the sea ice concentration exceeds 75%, and analyzed the monthly and seasonal changes characteristics. We used high-accuracy sea ice thickness products from NASA Ice Bridge to verify thickness retrieved from CryoSat-2 Satellite. The results show that there is a high consistency of r=0.72. The sea ice is thickest in spring and thinnest in summer. The thick sea ice concentrated around the north coast of Greenland and Ellesmere Island. Generally the MYI is thicker than the first-year ice FYI. Sea ice volume is largest in winter, about 23.30×10³ km³, almost a reduction of 70% after the summer melt. The seasonal fluctuation of the FYI volume is larger than the MYI.