青藏高原地面站积雪的空间分布和年代际变化特征

Spatial Distributions and Interdecadal Variations of the Snow at the Tibetan Plateau Weather Stations

作者选取了青海省和西藏自治区境内的72个气象站逐日观测的积雪深度资料,分析了青藏高原积雪的空间分布和年代际变化特征,结果表明:高原积雪的年变程并不完全一致,高原东南缘的积雪主要发生在3月份;高原东南和东北部的积雪一年有两个高值区:前冬10～12月,后冬2～4月;高原中部和西南部的积雪主要在隆冬12～1月;中部一些站点的积雪一年存在3个峰值:10月、1月和5月.青藏高原的积雪主要发生在10月至5月份,9月和6月的积雪相对来说很少,7月和8月基本无积雪.高原沿唐古拉山、念青唐古拉山、巴颜喀拉山、阿尼玛卿山以及喜马拉雅山坡的站点最早开始有积雪,8、9月份就会有积雪产生,并且这些地区最迟有积雪的月份也较晚,6、7月份还会有积雪存在;而柴达木盆地、青海湖盆地到湟水流域、沿雅鲁藏布江的河谷地带积雪出现得晚(10、11月),最迟出现积雪的月份却要早(5、6月份),雅鲁藏布江东段地带甚至最迟出现积雪的月份要提前到3、4月份.高原积雪存在三个高值中心:一是由喜马拉雅山脉北麓沿线各站组成的南部高值中心;二是唐古拉山和念青唐古拉山的东段山区;三是位于高原东部的阿尼玛卿山和巴颜喀拉山地区.青藏高原积雪总的来讲呈平缓的增长态势,20世纪60年代初积雪稍偏多,20世纪60年代中到20世纪70年代中是积雪偏少时期,20世纪70年代末到20世纪90年代是积雪偏多期.从20世纪60年代中到20世纪80年代末,积雪明显增加,20世纪90年代积雪又表现出减少的趋势.高原冬春多雪年为1983、1978、1982、1998、1993、1962、1968、1989、1995、1990;冬春少雪年为1965、1999、1984、1969、1985、1971、1976、1967、1960、1991.

By using the data of snow depth of 72 weather stations standing in Qinghai Province and Tibet Autonomous Region, the spatial distributions and interdecadal variations of the snow on the Tibetan Plateau are analysed. The result shows that the annual variations of snow are not fully consistent in different areas of the Plateau. The main snow falls in March on the Southeast edge of the Plateau, from October to December and from February to April in the Southeast and the Northeast Plateau, from December to January in the Middle and the Southwest Plateau. The snowfall exists in three main periods: October, January and May at several stations in the middle Plateau. The mean snowin the Plateau mainly falls from October to May, falls much fewer in Septmber and June, and almost no snow falls in July and August. We assume a year starts from August and ends in July. In the Plateau, the earliest snow starts in August or Septmber and the latest snow ends in June or July at the weather stations along the Tanggula Range, Nyainqentanggula Range, Bayan Har Mountains, A'nyemaqen Mountains and Himalayas Mountains. The snow of the Qaidam Basin, from Qinghai Lake Basin to the drainage area of the Huangshui River and in the basin of the Yarlung Zangbo River starts late (in October or November) and ends early (in May or June). The snowfall in the east basin of the Yarlung Zangbo River ends in March or April. There are three centers of the maximal snow on the Tibetan Plateau: the southern center at the northern foot of the Himalayas Mountains, the mountainous area in the east Tanggula Range and east Nyainqentanggula Range and the mountainous area in A'nyemaqen Mountains and Bayan Har Range on the east Plateau. The snow on the Tibetan Plateau increased over the last 40 years. The snow was rich at the initial stages of the 1960s, little from the middle stages of the 1960s to the middle stages of the 1970s, rich again from the later stages of the 1970s to the later stages of the 1990s. The snow obviously increased from the middle stages of the 1960s to the later stages of the 1980s, and decreased in the 1990s. The rich snow winter-spring years (from October of the previous year to May of the current year) are 1983, 1978, 1982, 1998, 1993, 1962, 1968, 1989, 1995 and 1990. The little snow winter-spring years are 1965, 1999, 1984, 1969, 1985, 1971,1976, 1967, 1960 and 1991.