淡水冰的微波发射率--湖冰和南极冰层-- Radiative transfer模拟与卫星辐射率
Microwave emissivity of fresh water ice--Lake ice and Antarctic ice pack--Radiative transfer simulations versus satellite radiances
摘要：
海冰的微波发射率模型的经验验证较差。典型的验证研究涉及使用平均或定型的配置文件的冰参数对平均辐射测量。测量点很少匹配，甚至更不经常逐点匹配。由于含盐量，海冰的复介电常数变化很大，难以预测。因此，检查一个典型的，平面平行，辐射传输为基础的冰发射率模型的有效性，我们将其应用于淡水冰，而不是盐水冰。湖冰的辐射模拟进行了比较，从高级微波扫描辐射计EOS（AMSR-E）苏必利尔湖的测量。AMSR-E测量也收集了南极冰盖。对于每个像素，一个热力学模型是由四年的欧洲中期天气预报中心（ECMWF）再分析数据和由此产生的温度分布驱动的发射率模型。结果表明，相对简单的发射率模型是一个很好的拟合数据。然而，这两种情况都显示出很大的差异，其最可能的解释是冰盖内以及多云大气中的散射。模型忽略了散射。还需要进一步的工作来完善冰发射率模型的散射部分，并对海冰内的复杂发射率进行准确的估计。
英文摘要：
Microwave emissivity models of sea ice are poorly validated empirically. Typical validation studies involve using averaged or stereotyped profiles of ice parameters against averaged radiance measurements. Measurement sites are rarely matched and even less often point-by-point. Because of saline content, complex permittivity of sea ice is highly variable and difficult to predict. Therefore, to check the validity of a typical, plane-parallel, radiative-transfer-based ice emissivity model, we apply it to fresh water ice instead of salt-water ice. Radiance simulations for lake ice are compared with measurements over Lake Superior from the Advanced Microwave Scanning Radiometer on EOS (AMSR-E). AMSR-E measurements are also collected over Antarctic icepack. For each pixel, a thermodynamic model is driven by four years of European Center for Medium Range Weather Forecasts (ECMWF) reanalysis data and the resulting temperature profiles used to drive the emissivity model. The results suggest that the relatively simple emissivity model is a good fit to the data. Both cases, however, show large discrepencies whose most likely explanation is scattering both within the ice sheet as well as by cloudy atmospheres. Scattering is neglected by the model. Further work is needed to refine the scattering component of ice emissivity models and to generate accurate estimates of complex permittivities within sea ice.
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