被动微波遥感在青藏高原积雪业务监测中的初步应用

Preliminary Application of Passive Microwave Data to Operational Snow Monitoring in Tibetan Plateau

积雪范围、积雪深度和雪水当量等参数的遥感监测与反演对气候模式的建立以及积雪灾害的评估具有重要意义。被动微波遥感在这些参数的反演方面具有明显优势,但目前尚未应用到青藏高原地区的积雪遥感业务监测上来。2001年10月至2002年4月,利用SSM/I数据对青藏高原地区的积雪范围和积雪深度进行了实时监测,为西藏、青海遥感应用部门提供逐日的雪深分布图。对这次监测的总效果进行了分析和评价,并对发生在青海省内一次较大的降雪过程进行了遥感分析,结果表明:SSM/I反演的积雪范围变化趋势与MODIS结果总体上较为一致;SSM/I的雪深监测结果为当地遥感部门对大于10cm的雪深做出正确判断提供了重要信息,是对雪灾定位的重要信息源。

Snow parameters, such as snow extent, snow depth and snow water equivalent are essential not only in understanding of land surface processes which is the basis of climate model but also in snow disaster assessment. Passive microwave remote sensing has advantages in retrieving these parameters, especially snow depth. However, this kind of technique has not been applied to monitoring snow in Tibetan Plateau so far. So we tried to monitor snow operationally in this area by means of SSM/I data since last winter, providing the local governmental sector with daily snow depth map. In the meantime, the in-situ snow depth data in Tibetan Plateau were collected to validate the retrieval algorithm employed in this study. In this paper, SSM/I images before and after a heavy fall of snow are analyzed and compared with MODIS images .The results show that the snow extent from SSM/I data is consistent with that from MODIS data, and that snow depths from SSM/I are very helpful for local snow assessment though SSM/I derived snow depth is significantly overestimated compared to in-situ data. With its retrieval algorithm being improved, passive microwave remote sensing has less effect of atmosphere and cloud and hence will be the most important tool in monitoring snow in Tibetan Plateau, especially when the new data of AMSR-E on board Aqua satellite are available.