西藏高原近40年积雪日数变化特征分析

利用近40 年(1971-2010 年) 西藏高原积雪日数资料, 分析了西藏高原积雪的时空分布特征。分析表明:藏东北部、南部边缘地区积雪较多, 年积雪日数在60 d 以上。近40 年来, 西部和东南部积雪日数呈显著减少的趋势, 除东南部各站、聂拉木和昌都积雪日数减少明显, 聂拉木减幅最大, 达到-9.2 d/10a, 其它各站地区积雪的变化趋势并不显著。西藏各区域积雪日数出现了准2 年、准4 年、准8 年、准14 年和准17~18 年的年代际周期, 南部边缘地区、东北部和西部地区积雪日数以10 年以下的周期为主。各区域积雪日数与冬季平均气温有明显的负相关, 但降水与积雪的相关在那曲中西部地区、沿江一线、东北部和南部边缘地区表现为明显的正相关。

Changes of the Snow Cover Days on Tibet Plateau in Last 40 Years

By using the snow cover days data on the Tibet Plateau during the period 1971-2010, the spatiotemporal changes of the snow cover days are analyzed. The results indicate that there is a snow cover of over 60 days in the fringe area of the northeastern and southern parts of the region. The snow cover days have a significant decreasing trend in the western and southeast parts, and the largest decline is observed in Nielamu, reaching 9.2d/ 10a. The snow cover days have quasi-cycles of 2 years, 4 years, 8 years, 14 years and 17-18 years acros the region, but quasi-cycles of 2 years, 4 years and 8 years occur in the southern and western parts. There is a significant negative correlation between the snow cover days and the mean winter air temperature, while there is a significant positive correlation between the snow cover days and precipitation in the central and western parts of Nagchu, the fringe areas of the northeast and the south margins and areas along the Yarlung Zangbo River.