Assessing moisture sources of precipitation in the Western Pamir Mountains (Tajikistan, Central Asia) using deuterium excess
Assessing moisture sources of precipitation in the Western Pamir Mountains (Tajikistan, Central Asia) using deuterium excess
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DOI：
10.1080/16000889.2019.1601987
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
T. Juhlke;C. Meier;R. van Geldern;K. Vanselow;Jakob Wernicke;J. Baidulloeva;J. Barth;S. Weise
中科院分区：
文献类型：
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作者：
T. Juhlke;C. Meier;R. van Geldern;K. Vanselow;Jakob Wernicke;J. Baidulloeva;J. Barth;S. Weise
摘要海洋来源的空气湿度可以进行远距离传输，并可能有助于在遥远的地方降水。随着气候的不断变化，水汽源和汇之间的关系也在不断演变，并在水收支评估中发挥着重要作用。本研究分析了来自西帕米尔山脉（塔吉克斯坦）两个野外站点的月综合和基于事件的降水样品，以获得水的氧（δ 18 O）和氢（δ 2 H）的稳定同位素组成。目的是调查水蒸气来源，特别是评估地中海区域水蒸气的贡献。后者经常被假定为中亚潜在的水分来源区域。氘过量值（d），作为一个指纹的水分来源，低于13‰的月综合样品，在一年的大部分时间。这表明地中海高湿度（约20‰）对西帕米尔山脉的贡献比原先预期的要小。在3月份观察到最大d值为19‰，这与冬季地中海贡献增加的常见观察结果（DJF）不一致。一个拉格朗日后向轨迹模式（HYSPLIT）被用来推断一般的空气质量的起源采样降水事件。“西部”水分的40%的最大贡献也检测到在3月，而40%-60%的水分，有助于在冬季降水事件的轨迹，起源于北方印度洋。
Abstract Air moisture of oceanic origin can be subject to long-range transport and could contribute to precipitation at distant places. With ongoing climate change the relationship between water vapour sources and sinks is under constant evolution and plays an important role for water budget assessments. This study analysed monthly integrated and event-based precipitation samples from two field sites in the Western Pamir Mountains (Tajikistan) for stable isotope compositions of oxygen (δ18O) and hydrogen (δ2H) of water. The aim was to investigate water vapour sources and, in particular, to evaluate contributions of water vapour from the Mediterranean region. The latter has been often postulated as a potential moisture source region for Central Asia. Deuterium excess values (d), that serve as a fingerprint of moisture origin, were below 13‰ in monthly integrated samples, for most of the year. This indicates a smaller contribution of high Mediterranean moisture (∼20‰) to the Western Pamir Mountains than originally expected. A maximum d value of 19‰ was observed in March, which is not in agreement with the common observation of increased Mediterranean contribution during winter (DJF). A Lagrangian backward trajectory model (HYSPLIT) was applied to infer the general air mass origin for sampled precipitation events. A maximum contribution of ‘western’ moisture of 40% was also detected in March, while 40%–60% of moisture that contributed to precipitation events in winter was transported by trajectories that originated from the Northern Indian Ocean.