基于时空变化参数的青藏高原被动微波雪水当量反演研究

Qinghai-Tibet Plateau is an important snow cover area in China. Snow water equivalent (SWE) over plateau region is the vital input for hydrology and energy model, so monitoring SWE is of great significance. We use passive microwave remote sensing to obtain SWE spatial and temporal distribution information, because ground stations are less and some lacks of snow observations. Due to the Tibetan Plateau often experiences the shallow snow, traditional snow algorithms (19-37GHz) is different meet the accuracy requirements. The global snow operational algorithm has a relatively large error when applied in this area. Considering high-frequency is sensitive to the shallow snow, we attempt to develop a high-frequency algorithm for shalow snow, and correct the atmosphere affect simultaneously. Snow cover in Tibetan Plateau region has the long time, that will have a snow deformation (particle size, density and depth are time-varying). Based on the above considerations of the issue, snow radiative transfer model based on snow deformation model is developed. We analyze the sensitivity of snow physical properties change for traditional gradient algorithm. Using the space extention of snow evolution model and field measurement of the experimental points, we will get the distribution of snow grain size, density, and other climatology characteristics over Tibetan Plateau. All of those will benefit for retrieve a snow algorithm of space-time the parameter variable; Finally, the operational SWE production is product based on the algorithm.

青藏高原是我国重要的积雪分布区域，积雪雪水当量是高原区域水文、能量模型的重要输入，其监测具有重要的意义。由于地面台站分布少，部分台站缺乏积雪观测等原因，常用被动微波遥感获取雪水当量时空分布信息。因青藏高原区域积雪较薄，传统积雪算法（19-37GHz）容易穿透，因而难以满足反演需求，全球积雪产品在青藏高原区域验证精度不高。本研究利用高频对薄雪敏感的特点尝试开展薄雪的高频算法，同时开展积雪辐射大气影响模拟和校正的研究工作；考虑青藏高原积雪周期长，存在着积雪的演化变形过程（粒径、密度和深度随时间发生变化），研究开展基于积雪演化变形模型的积雪辐射传输综合模型。并进行积雪物理性质的变化对于传统梯度算法的敏感性分析，厘定不同积雪粒径等对应的积雪算法系数，完成青藏高原区域积雪粒径、密度等气候学特征分布，结合两种算法的优点，形成时空参数可变的积雪反演算法开发；最后进行基于上述算法的雪水当量业务化产品生产。

青藏高原是我国重要的积雪分布区域，积雪雪水当量是高原区域水文、能量模型的重要输入，其监测具有重要的意义。由于地面台站分布少，部分台站缺乏积雪观测等原因，常用被动微波遥感获取雪水当量时空分布信息，本研究采用以微波遥感数据为主，通过地面观测数据、微波辐射计观测和模型模拟等手段，瞄准青藏高原的积雪分布特征，发展了基于微波大气校正的积雪时空反演算法和开展了积雪数据产品的研发工作。主要取得的成果有： 1）定量化地厘定了微波大气影响，发展了微波大气校正的影响方法，并开展了分析研究，2）开展了微波辐射模型和积雪演化模型的模拟，构建了耦合的模型；3）发展了青藏高原地区无云积雪数据产品，该数据可为微波遥感雪水当量提供判别的有效依据。办研究共发表论文20篇，其中相关研究SCI 6篇，EI6篇，发布了2套积雪遥感数据产品，参与编写专注一本，获得国家发明1项，在申请3项目。