Isotopic composition and origin of snow over Siberia
Isotopic composition and origin of snow over Siberia
复制标题
DOI：
10.1029/2004jd005053
复制
发表时间：
2005-07
影响因子：
--
通讯作者：
N. Kurita;A. Sugimoto;Y. Fujii;T. Fukazawa;V. Makarov;O. Watanabe;K. Ichiyanagi;A. Numaguti;N. Yoshida
中科院分区：
文献类型：
--
作者：
N. Kurita;A. Sugimoto;Y. Fujii;T. Fukazawa;V. Makarov;O. Watanabe;K. Ichiyanagi;A. Numaguti;N. Yoshida
[1]西伯利亚积雪的空间同位素分布，那里的冬季温度一样冷的极地地区，观察了跨西伯利亚积雪调查（TSSS）和跨Verkhoyansk积雪调查考察（TVSSE）在2000年3月和2001年3月。结果表明，内陆δ D亏损和略有增加的氘过量值，d，在西伯利亚积雪。为了探索源区变化和雪的同位素组成之间的关系，进行了模型模拟，再现了所观察到的雪的同位素组成。西伯利亚降水的水汽来源估计使用气候系统研究中心/国家环境研究所（CCSR/NIES）大气环流模式（AGCM）。一个简单的同位素模型被用来评估总同位素的变化过程中，从指定的源区的降水区域的传输。结果表明，各源对积雪贡献的变异性导致了较大的同位素变异性，模式再现了观测到的内陆积雪δ D的损耗，这表明GCM预测的源贡献与观测值相符。然而，模拟的d值与西伯利亚上空观测到的d值不匹配。降水中d值的观测结果表明，在秋季增加，在深秋达到最大值，然后在冬季减少;然而，模拟的d值在初秋达到最大值，在冬季减少到最小值。简单的同位素模式没有考虑额外的水分蒸发加入从源区移动的气团。因此，雪的模拟和观测的d值之间的不一致表明，在运输过程中从陆地表面提供的水分显着有助于秋季降雪。增加的d值的西伯利亚雪表明，蒸发从开放的水或从土壤表面，这是伴随着同位素分馏，是更重要的比蒸腾通量，这并不改变同位素含量。从开阔水域蒸发的陆地水分的贡献在东西伯利亚降雪中起着重要作用。
[1] The spatial isotopic distribution of the snowpack over Siberia, where winter temperatures are as cold as those of the polar regions, was observed by the Trans-Siberian Snow Survey (TSSS) and Trans-Verkhoyansk Snow Survey Expedition (TVSSE) in March 2000 and March 2001. The results show inland δD depletion and a slightly increasing deuterium excess value, d, in the snowpack over Siberia. To explore the relationship between source region variability and the isotopic composition of snow, a model simulation was performed that reproduced the observed isotopic composition of snow. Moisture sources for Siberian precipitation were estimated using the Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES) atmospheric general circulation model (AGCM). A simple isotopic model was used to evaluate the total isotopic changes during transport from the designated source region to the region of precipitation. The results showed that the variability of the contribution of each source to the snow results in large isotopic variability, and the fact that the model reproduced the observed inland depletion of δD in snowpack suggests that GCM-predicted source contributions were verified by observed values. However, the modeled d values did not match observed d values over Siberia. Observations of d values in precipitation show an increase during autumn toward a maximum in late autumn and then a decrease during winter; however, the modeled d value reached a maximum in early autumn and decreased toward a minimum in winter. The simple isotope model does not consider additional moisture evaporation joining an airmass moving from a source region. Therefore the disagreement between the modeled and observed d values of snow suggests that moisture supplied from the land surface during transportation significantly contributes to autumn snow. The increased d values of Siberian snow show that evaporation from open water or from the soil surface, which are accompanied by isotopic fractionation, are more important than transpiration flux, which does not change the isotopic content. The contribution of land-derived moisture that has evaporated from open water plays an important role in eastern Siberian snow.