【作者】 蒋玲梅；

【导师】 李小文； 施建成；

【作者基本信息】 北京师范大学 ， 地图学与地理信息系统， 2005， 博士

【摘要】 积雪是气象学和水文学中一个非常重要的参数。积雪的多寡不仅是影响气候变化的重要因子,也是影响干旱和半干旱地区农牧业发展的重要因素。季节性雪盖和冰川是全球水循环中的重要成分,监测季节性雪覆盖的范围以及冰川的堆积和消融地带,对于理解全球水循环是十分必要的。本论文的研究目的是改进当前AMSR-E传感器的雪水当量算法。我们用考虑多次散射的积雪辐射理论模型──Matrix Doubling法求解辐射传输方程,用致密介质理论模型模拟积雪发射和消光特性,用AIEM模型模拟地表辐射及作为辐射传输方程的边界条件,来模拟和分析不同积雪参数和地表参数对积雪总辐射和亮温差的影响,指出当前反演算法中存在的问题,并用地面实验数据对该模型做了验证。为了发展雪水当量(或积雪深度)算法,我们对不同散射阶模型(零阶、一阶和本论文采用的多次散射模型)做了比较,结果表明我们必须在前向理论模型和反演模型中考虑多次散射作用。利用积雪理论模型,我们建立了针对AMSR-E传感器参数设置的积雪辐射模拟数据库,包含了各种可能的自然积雪和地表特性参数。从而在模拟数据库基础上,我们发展了针对AMSR-E的参数化模型。最后,我们提出了发展雪水当量反演算法框架。本论文的研究重点和创新点表现在:(1)对现有积雪辐射理论模型与雪水当量反演模型认识上的突破:我们利用理论AIEM面辐射模型,考虑了有积雪覆盖的下垫面粗糙度、介电特性的影响,而当前的前向理论辐射模型与反演模型中都把积雪-土壤、积雪-空气界面作为平面处理。不同散射阶模型──零阶、一阶与多阶模型的比较,表明高频(频率> ku波段)多次散射作用不可忽略,因此必须在我们的雪当量反演算法中考虑多次散射作用;(2)用实验数据对包括地表介电常数和粗糙度效应,且考虑多次散射的积雪辐射模型做验证,验证结果表明我们所选用的积雪辐射模型能描述自然积雪的辐射特性;(3)建立了积雪辐射模拟数据库,该数据库包括了几乎所有的自然雪特性──积雪密度、颗粒大小,以及地表介电常数、地表粗糙度特征──冻土/非冻土、土壤湿度和粗糙度特征。通过对模拟数据库的分析,我们发展了针对AMSR-E传更多还原

【Abstract】 Snow is a key element in the meteorological and hydrological studies. The amount of regional snow plays an important role in the climate change and also affects greatly the development of agriculture and farming industries in arid/semi-arid areas. Seasonal snow cover and glacier are important components of global water cycling. Thus, it is necessary to monitor the seasonal snow cover, the depositing and melting of the glacier. It will help us to acquire a more accurate understanding of global water cycling.In this study, we evaluate the capability of a multi-scattering microwave emission model that including the Dense Media Radiative Transfer Model (DMRT) and AIEM in simulation of dry snow emission with Matrix Doubling approach. We compared the predictions of this model with the ground experimental measurements. The comparison showed that our snow microwave emission model agreed well with the experimental measurements. In order to develop retrieval snow properties: snow depth or snow water equivalence (SWE) retrieval algorithm, we carried out the sensitivity test between the emission models with the different scattering-order: the zeroth-order, the first-order and the multi-scattering models. The results indicated that the multi-scattering effects have to be taken into account in the snow emission model, especially for large grain size. Due to the complexity of the multi-scattering model, we developed a parameterized inversion model using our multi-scattering emission model with a wide range of snow and under-ground properties for algorithm development purpose. Finally, we proposed a technique retrieval to estimate snow water equivalence.There are some new results obtained as follows in this study.1. New understanding of the snow microwave emission model and snow water equivalence (SWE) inversion algorithm. First, using AIEM model, we can take into account the properties of underground surface roughness and dielectric constant in the snow emission model, while in current emission更多还原