Monsoon onset signal in the stable oxygen and hydrogen isotope ratios of monsoon vapor
Monsoon onset signal in the stable oxygen and hydrogen isotope ratios of monsoon vapor
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DOI：
10.1016/j.atmosenv.2015.02.062
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发表时间：
2015-05
影响因子：
5
通讯作者：
R. Srivastava;R. Ramesh;Naveen Gandhi;R. A. Jani;Ashutosh Singh
中科院分区：
文献类型：
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作者：
R. Srivastava;R. Ramesh;Naveen Gandhi;R. A. Jani;Ashutosh Singh
虽然关于氘（D）和氧（18 O）的数据，水文过程的有效示踪剂，可用于全球降水量，这种数据的大气水蒸气是有限的。随着能够测量大气水蒸气中D的卫星的出现，如果信号远高于噪声，则可以早期检测到中尺度水分输送过程（例如季风）。我们对大气水汽稳定氧和氢同位素组成的日常测量结果（δ 18 O蒸汽，δ D蒸汽）和降雨2007-2008年CE期间印度阿赫梅达巴德上空（δ 18 Orain，δDrain）的变化表明确实如此：（1）季风爆发的标志是δ 18 O和δDvapor分别下降了1.29 ‰和1.60 ‰，氘过剩（δD - 8.（ii）δ 18 Ovapor、δDvapor、δ 18 Orain和δ Drain在季风季节（6月中旬至9月中旬）表现出相关变化：大暴雨期间δ 18 Ovapor和δ Dvapor的日变化较大，与平均值有明显的负偏离。氘过量的蒸汽和雨是无法区分彼此，在其自然变化，符合它们之间的同位素平衡的实现。
Whereas data on deuterium (D) and oxygen (18O), effective tracers of hydrological processes, are available for global precipitation, such data on atmospheric water vapor are limited. With the advent of satellites capable of measuring D in atmospheric water vapor, mesoscale moisture transport processes (e.g. monsoons) could be detected early provided the signal is well above the noise. Our results of daily measurements of stable oxygen and hydrogen isotopic compositions of atmospheric water vapor (δ18Ovapor, δDvapor) and rain (δ18Orain, δDrain) during 2007–2008 CE over Ahmedabad, India, show that this is indeed so: (i) the onset of monsoon is marked by a dramatic decrease of ∼2.9‰ and ∼60‰, in δ18Ovapor, δDvapor, respectively, and 46‰ in deuterium excess (δD – 8. δ18O) of local atmospheric water vapor (ii) δ18Ovapor, δDvapor, δ18Orainand δDrainexhibit correlated variations during the monsoon season (mid-June to mid-September): the daily variations of δ18Ovaporand δDvaporare higher during large rain events, with sharp negative excursions from mean values. Deuterium excess of vapor and rain are indistinguishable from each other, within their natural variability, consistent with the achievement of isotopic equilibrium between them.