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首页> 外文期刊>IEEE Transactions on Geoscience and Remote Sensing >The Effects of Layers in Dry Snow on Its Passive Microwave Emissions Using Dense Media Radiative Transfer Theory Based on the Quasicrystalline Approximation (QCA/DMRT)
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The Effects of Layers in Dry Snow on Its Passive Microwave Emissions Using Dense Media Radiative Transfer Theory Based on the Quasicrystalline Approximation (QCA/DMRT)

机译：基于准晶体近似（QCA / DMRT）的稠密介质辐射传输理论，干雪中的层对其无源微波辐射的影响

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摘要

A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be 5 K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy.
机译：与均质雪堆和其他散射模型确定的排放相比，基于稠密介质辐射传输（DMRT）理论和准晶体近似（QCA）的多层干燥雪堆微波发射模型提供了更准确的结果。 DMRT模型考虑了粘合剂的聚集效应，这会通过使用粘性粒子模型导致密介质Mie散射。使用多层模型，我们检查了代表性积雪的频率和亮度温度（Tb's）的频率和偏振相关性，并将它们与单层模型的结果进行了比较，发现多层模型预测的偏振差更高，两倍大且更弱频率依赖性。我们还研究了多层积雪中Tb的时间演变。 Tb在18.7 GHz和36.5 GHz之间的差异可以比本文中的单层模型预测低5K。通过使用来自冷地过程现场实验的积雪观测数据作为多层模型和单层模型的输入，它表明，与单层模型相比，多层Tb与数据的一致性更好。使用一组物理参数，多层QCA / DMRT模型可同时匹配Tb观测的所有四个通道，而单层模型只能再现垂直极化的Tb。同样，使用相同的一组物理参数，多层模型可以精确地匹配偏振差异和频率依赖性。因此，用于获取积雪深度或水当量的算法应基于多层散射模型，以实现更高的精度。

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