Evaluation of AMSR-E Thin Ice Thickness Algorithm from a Mooring-Based Observation: How Can the Satellite Observe a Sea Ice Field with Nonuniform Thickness Distribution?
Evaluation of AMSR-E Thin Ice Thickness Algorithm from a Mooring-Based Observation: How Can the Satellite Observe a Sea Ice Field with Nonuniform Thickness Distribution?
复制标题
DOI：
10.1175/jtech-d-18-0218.1
复制
发表时间：
2019-08-01
影响因子：
2.2
通讯作者：
Tamura, Takeshi
中科院分区：
文献类型：
--
作者：
Kashiwase, Haruhiko;Ohshima, Kay, I;Tamura, Takeshi
沿海冰间湖海冰产生的量化是了解全球气候系统的关键问题。在本研究中，我们直接将先进微波扫描辐射计-EOS (AMSR-E) 数据与 2003 年冬季鄂霍次克海萨哈林岛附近系泊观测获得的海冰厚度分布进行比较，以评估沿海冰间湖海冰厚度估算算法。通过使用热冰厚度作为目标物理量，我们发现所获得的极化比（PR）和冰厚度之间的关系可以提供合适的AMSR-E算法来估计薄冰厚度，无论冰厚度场是均匀还是非均匀。 PR 值与热冰厚度之间的关系同样与在单个浮冰上观察到的局部 PR-厚度关系一致。这是因为 PR 值和热冰厚度都对较薄的冰更敏感。此外，我们通过与系泊数据进行比较，对沿海冰间湖中活性冰湖的检测方法进行了评估，随后对其进行了修改，将沿海冰间湖分为三种薄冰类型，即活性冰湖、薄固体冰和混合冰（活性冰湖和薄固体冰的混合物）。改进后的算法即使对于萨哈林岛附近规模相对较小的冰间湖也能成功地表示热冰厚度，并且由于其高度通用性，预计将有助于更好地量化全球海洋的海冰产生。
The quantification of sea ice production in coastal polynyas is a key issue to understand the global climate system. In this study, we directly compared Advanced Microwave Scanning Radiometer-EOS (AMSR-E) data with the sea ice thickness distribution obtained from a mooring observation during the winter of 2003 off Sakhalin in the Sea of Okhotsk to evaluate the algorithm for estimation of sea ice thickness in coastal polynyas. By using thermal ice thickness as a target physical quantity, we found that the obtained relationship between the polarization ratio (PR) and ice thickness can provide an appropriate AMSR-E algorithm to estimate thin ice thickness, irrespective of the uniform or nonuniform ice thickness field. The relationship between the PR value and thermal ice thickness is likewise consistent with the local PR-thickness relationship that is observed at individual ice floes. This is because both the PR value and thermal ice thickness are more sensitive to thinner ice. Furthermore, we evaluated the method for detection of active frazil in a coastal polynya by comparing with the mooring data, and subsequently modified it to classify the coastal polynya into three thin ice types, namely, active frazil, thin solid ice, and mixed ice (mixture of active frazil and thin solid ice). The improved algorithm successfully represents the thermal ice thickness even for a relatively small-scale polynya off Sakhalin and is expected to be useful for better quantification of sea ice production in the global ocean owing to its high versatility.