The relations between soil surface emissivity and soil temperature are simulated through the AIEM model using the AMSR-E 6. 9,10. 65 and 18. 7 GHz channels,observing characteristics for a given soil structure and roughness but different moisture. Analysis showed that the emissivity in v-polarization which are different only when the soil moisture varies,have no significant dependence on the soil temperature. By calculating the Normalized Microwave Difference Index (NMDI) of two channels, the relations between soil moisture and NMDI are established and then used in the soil moisture retrieval of the Taklama-kan desert central region. We find that 18. 7 and 10. 65 GHz channels are the best combination in the soil moisture retrieval. Based on the above,three semi-empirical surface emission models including Q/H,Hp and Qp model are used in simulating the relation between soil moisture and NMDI. Results tell us that these three models have very little differences in the soil moisture retrieval and they coincide well with the soil moisture result calculated using AIEM model.%在给定土壤质地和粗糙度状况条件下,用AIEM模型模拟AMSR-E的6.925GHz、10.65GHz和18.7GHz频率下不同含水量时土壤表面发射率和土壤温度的关系,分析表明V极化的发射率受土壤温度的影响很小,其变化主要由土壤水分的变化引起.通过计算不同频率组合V极化通道的归一化微波差异指数,并模拟与土壤水分的关系,然后利用这一关系对塔克拉玛干沙漠中部某地的土壤水分进行反演.结果发现用18.7GHz和10.65GHz V极化通道组合的反演值与AMSR-E Level 3土壤水分产品的吻合程度最好.在此基础上分别用3种常见的半经验表面散射模型:Q/H模型、Hp模型和Qp模型,通过计算上述通道组合的NMDI来反演研究区的土壤水分,结果表明利用3种半经验模型得到的反演值之间差异非常小,并且与用AIEM模型计算NMDI时的反演结果吻合较好.
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