被动微波遥感估算雪水当量研究进展与展望

THE DEVELOPMENT AND PROSPECT OF ESTIMATING SNOW WATER EQUIVALENT USING PASSIVE MICROWAVE REMOTE SENSING DATA

被动微波遥感可以透过云层 ,全天候地提供地表一定深度的信息。星载被动微波遥感传感器的时间分辨率很高 ,在冰冻圈动态研究中有着重要的地位。在最近的二三十年中 ,大量被动微波遥感的应用都是在美国、加拿大、欧洲等地 ,而我国在这方面的研究相对较少。首先介绍了被动微波遥感数据在监测积雪方面的国内外研究进展 ,对现存的雪水当量 (SWE)估算算法 (和模型 )的适用性进行讨论。然后 ,详细讨论了我国西部的青藏高原地区雪水当量的估算 ,阐明了利用SSM /I数据估算青藏高原地区雪水当量的复杂性 ,并指出了其复杂性产生的原因 ,提出了解决问题的方法 。

Snow water equivalent (SWE) is an important factor in the variable study of snow storage. However, the only adequately way to estimate the spatial coverage and temporal changes of snow cover in a regional scale is via remote sensing. Passive microwave data, as a complement for visible remote sensing data, despite of its coarse resolution, have the capability to penetrate clouds and snow cover and to provide dual polarization information at different frequencies. In fact, passive microwave remote sensing has played a key role in cryosphere research field in past three decades. This paper reviews the researches of monitoring snow using passive microwave remote sensing data at home and abroad. The applicability of existing algorithms (and models) to estimate snow water equivalent is assessed. Then, the retrieval of SWE in the Qinghai Tibetan plateau is discussed in detail, to illustrate the complexity of the estimating SWE using SSM/I data in the special region, and to clarify the reasons that lead to the complexity. Finally, a series of methods and solutions are offered, which provide the theory basis for the further dynamic monitoring on snow in the Qinghai Tibetan plateau regions. For improving the retrieval accuracy, several aspects should be taken into account, such as detecting wet snow and dry snow, distinguishing the snow cover and frozen soil in the SSM/I sub pixel, and comparison of retrieval results and observation data.