摘要
１９９７ 年希夏邦马峰达索普冰川冰芯科学考察中发现， 在海拔５ ８００ ｍ 和７ ０００ ｍ 降雪中δ１８ Ｏ 值同时在９ 月９～１９ 日有一个很大的突变， 这主要是由不同的类型降水气团产生的当时海拔７ ０００ ｍ 实地观测和天气图都表明这一时期正好是西南季风和西风环流的转换时期 由西南季风引起的海洋气团因沿途多次降水过程的分馏，使水汽中δ１８ Ｏ 含量已经很低，所以海洋气团在希夏邦马峰凝结后降雪中的δ１８ Ｏ 必然也很低； 而由西风环流带来的降水气团主要为青藏高原内部湖泊、河流水汽蒸发所产生的， 这些湖泊、河流， 特别是湖泊正好是δ１８ Ｏ 富集之处 因此， 从这些水面蒸发所产生的水汽， 携带的δ１８ Ｏ 含量亦很高另外， 样品中的阳离子浓度大小顺序和 Ｃａ２＋ 离子浓度在９ 月９～１９ 日前后降雪中显著的差别。
Changes of vapor sources in Dasuopu Glacier on Peak Xixabangma are discussed in this paper on the interpretation of δ 18 O of snowfalls varying from September 4 to Octeber 2, 1997 δ 18 O is lower before the stable establishment of the westerlies and sharply increases afterwards The weather is mainly controlled by maritime air masses until its retreat, which is characterized by the depleted heavy isotopes because of multi stage fractionations during the incursion of maritime air masses to Peak Xixabangma After the westerlies establishment, δ 18 O increases about 12‰ at 5 800 m a s l and 10‰ at 7 000 m a s l This can be attributed to the enrichment of δ 18 O due to the evaporation in precipitation process in the interior of the Tibetan Plateau This conclusion is verified by the order of cation concentrations and the relatively high cation concentrations (especially Ca 2+ ) after September 19, which suggest that there is a westerly source, because of vast arid regions lying in the western regions of the Tibetan Plateau and being a large source of desert dust rich in Ca 2+
出处
《冰川冻土》
CSCD
北大核心
1999年第3期237-241,共5页
Journal of Glaciology and Geocryology
基金
"九五"国家攀登项目
中国科学院 "九五"重大项目
国家自然科学基金
