Influence of changing atmospheric circulation on precipitation delta O-18-temperature relations in Canada during the Holocene
Influence of changing atmospheric circulation on precipitation delta O-18-temperature relations in Canada during the Holocene
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DOI：
10.1006/qres.1996.0061
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发表时间：
1996-11-01
影响因子：
2.3
通讯作者：
MacDonald, GM
中科院分区：
文献类型：
--
作者：
Edwards, TWD;Wolfe, BB;MacDonald, GM
重建了加拿大两个地区的冰期后降水三角洲（18）O历史。安大略省南部年降水(δ (18)O(p))氧同位素组成的长期变化似乎在过去11500 C-14年期间以一致的同位素-温度关系发生过。加拿大中部靠近现代北方树线的现代同位素-温度关系显然是在5000至4000年前建立的，尽管末次冰期极大期和消冰期的关系也可能与现在相似。然而，在全新世早期，尽管局部温度较低，但异常高的δ (18)O(p)明显持续存在，这可能与高纬向指数有关。一项初步的敏感性分析表明，穿越西科迪勒拉山脉的太平洋气团中水汽蒸馏量的小幅减少，或许伴随着夏季：冬季降水比的增加，可能是观测到的影响的原因。随着早全新世大气环流模式的变化，北美西部其他地区也出现了相当的同位素温度“异常”，这表明在此期间北美三角洲（18）O(p)的时间片图可能为使用同位素水示踪剂测试和验证大气环流模式模拟提供了有用的目标。(C) 1996年华盛顿大学
Postglacial precipitation delta(18)O history has been reconstructed for two regions of Canada. Long-term shifts in the oxygen-isotope composition of annual precipitation (delta(18)O(p)) in southern Ontario appear to have occurred with a consistent isotope-temperature relation throughout the past 11,500 C-14 yr. The modern isotope-temperature relation in central Canada near present boreal tree-line evidently became established between 5000 and 4000 years ago, although the relation during the last glacial maximum and deglaciation may also have been similar to present. In the early Holocene, however, unusually high delta(18)O(p) apparently persisted, in spite of low temperature locally, probably associated with high zonal index. A rudimentary sensitivity analysis suggests that a small reduction in distillation of moisture in Pacific air masses traversing the western Cordillera, perhaps accompanied by a higher summer:winter precipitation ratio, could have been responsible for the observed effect. Equivalent isotope-temperature ''anomalies'' apparently occurred elsewhere in western North America in response to changing early-Holocene atmospheric circulation patterns, suggesting that a time-slice map of delta(18)O(p) for North America during this period might provide a useful target for testing and validation of atmospheric general circulation model simulations using isotopic water tracers. (C) 1996 University of Washington