Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters-猫眼课题宝

DOI：

10.5194/tc-10-837-2016

发表时间：

2015-11

期刊：

The Cryosphere

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

A. Touzeau;A. Landais;B. Stenni;R. Uemura;K. Fukui;S. Fujita;S. Guilbaud;A. Ekaykin;M. Casado;E. Barkan;B. Luz;O. Magand;G. Teste;E. L. Meur;M. Baroni;J. Savarino;I. Bourgeois;C. Risi

冰芯中氧和氢的同位素组成是重建过去气候变化的宝贵工具。单独使用时，它们可以深入了解当地温度的变化，而结合起来，它们可以提供有关湿气起源点的气候条件的信息。然而，最近对浅坑积雪的分析表明，由于局部积雪再造过程，气候信号可能在非常低的积雪区被抹去。信噪比降低，气候信号只能通过几个雪坑的叠加来获取。显然，在这个阶段，信号并没有完全消失，否则就不可能像上次冰期那样，从冰芯中提取有价值的气候信息。为了更好地理解气候信号是如何从降水传递到雪的，我们在这里展示了来自东南极洲不同雪样本的结果。首先，我们从地理角度来看同位素和温度之间的关系，利用三次穿越南极洲的结果，看看这种关系是如何通过蒸馏过程建立起来的。我们还利用这些措施来了解二阶参数（d-excess和17 - O-excess）与δ 18o的关系以及它们是如何被控制的。d-过量在大陆内部增加（即δ 18o减少），这是由于蒸馏过程，而17 -过量在偏远地区减少，这是由于低温下的动力学分馏。在这两种情况下，这些更改都与有关源的原始信息的丢失有关。然后，我们在Dome C和Vos-tok收集的1年降水样本以及Dome C的地表雪中观察了相同的关系。我们注意到，与来自穿越的样品相比，这些样品的δ 18o与温度(T)关系的斜率减小，因此在使用过去的空间斜率时提倡谨慎。Touzeau等：东南极洲气候重建中地表积雪同位素组成的获取。二阶参数在降水中的表现与在地表积雪中的表现相同，这表明类似的过程是活跃的，并且它们在源气候参数方面的解释因东南极洲的局地温度效应而非常复杂。最后，我们检验了四个雪坑的雪中δ 18o与二阶参数之间是否也存在相同的关系。在Vostok地区，δ 18 O与δ 18 O呈负相关关系，而δ 18 O与δ 18 O呈负相关关系。这可能是由于该地点的平流层影响和/或沉积后的过程。

The isotopic compositions of oxygen and hydrogen in ice cores are invaluable tools for the reconstruction of past climate variations. Used alone, they give insights into the variations of the local temperature, whereas taken together they can provide information on the climatic conditions at the point of origin of the moisture. However, recent analyses of snow from shallow pits indicate that the climatic signal can become erased in very low accumulation regions, due to local processes of snow reworking. The signal-to-noise ratio decreases and the climatic signal can then only be retrieved using stacks of several snow pits. Obviously, the signal is not completely lost at this stage, otherwise it would be impossible to extract valuable climate information from ice cores as has been done, for instance, for the last glaciation. To better understand how the climatic signal is passed from the precipitation to the snow, we present here results from varied snow samples from East Antarctica. First, we look at the relationship between isotopes and temperature from a geographical point of view, using results from three traverses across Antarctica, to see how the relationship is built up through the distillation process. We also take advantage of these measures to see how second-order parameters (d-excess and 17 O-excess) are related to δ 18 O and how they are controlled. d-excess increases in the interior of the continent (i.e., when δ 18 O decreases), due to the distillation process, whereas 17 O-excess decreases in remote areas, due to kinetic fractionation at low temperature. In both cases, these changes are associated with the loss of original information regarding the source. Then, we look at the same relationships in precipitation samples collected over 1 year at Dome C and Vos-tok, as well as in surface snow at Dome C. We note that the slope of the δ 18 O vs. temperature (T) relationship decreases in these samples compared to those from the traverses, and thus caution is advocated when using spatial slopes for past Published by Copernicus Publications on behalf of the European Geosciences Union. 838 A. Touzeau et al.: Acquisition of isotopic composition for surface snow in East Antarctica climate reconstruction. The second-order parameters behave in the same way in the precipitation as in the surface snow from traverses, indicating that similar processes are active and that their interpretation in terms of source climatic parameters is strongly complicated by local temperature effects in East Antarctica. Finally we check if the same relationships between δ 18 O and second-order parameters are also found in the snow from four snow pits. While the d-excess remains opposed to δ 18 O in most snow pits, the 17 O-excess is no longer positively correlated to δ 18 O and even shows anti-correlation to δ 18 O at Vostok. This may be due to a strato-spheric influence at this site and/or to post-deposition processes .

Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

文献摘要

相似文献