基于MODIS的青藏高原雪线高度遥感监测

Monitoring of Snowline Altitude over the Tibetan Plateau based on MODIS Data

雪线作为区分积雪覆盖区与无雪区的边界线,是冰冻圈各要素中对气候变化最为敏感的指示器。利用去云后的MODIS积雪面积比例产品并结合DEM数据,通过雪线像元及其高度的提取、雪线高度场的建立,对青藏高原近12a（2000～2011年）雪线高度的时空变化特征进行了分析。结果表明：青藏高原雪线高度的分布受地形的影响,高原内部的雪线高度明显高于周围山区;在近12a中,青藏高原的雪线高度变化虽然没有明显的年际变化趋势（升高或者降低）,但是体现出较高的年内和年际波动特征,特别是青藏高原的东部和南部地区由于受西南季风的影响,夏季雪线高度的年际变化尤为强烈。提出基于MODIS的雪线高度提取方法具有较好的应用潜力,能够适用于其他地方雪线高度的遥感监测。

As the boundary that separates snow-covered areas from snow-free areas, the snowline is the most sensitive indicator for monitoring climatic behavior among all the cryosphere elements. In this paper, the snowline altitude over the Tibetan Plateau （TP） during 2000 to 2011 are extracted using the cloud-removed MODIS fractional snow cover products combining with DEM, and the spatiotemporal changes of snowline altitude are examined. The proposed MODIS-based snowline altitude extracting methodology include the determination of snowline pixel and its altitude,and the establishment of snowline altitude field. The re- sults show that due to the complex terrain,the snowline altitude in the interior of the TP is obviously high- er than the peripheral mountainous area. A strong seasonal and interannual variability of snowline altitude is discovered,although there is no obvious trend of snowline altitude change during the examined period. Especially,the east and south of the TP,due to the influence of summer monsoon, there are very large in- terannual fluctuations of snowline altitude in the summer months. The MODIS-based snowline altitude ex- tracting method was described in this paper,which has a good application potential in SLA monitoring for any other regions.