Isotope climatology and paleoclimatology of Western Canada

拟议的研究将确定大气环流的模式和强度的变化如何影响加拿大西部的气候在两个重要的时间段：（1）过去的世纪和（2）过去的千年。这些调查的基础是对降水中天然存在的氢和氧重同位素的相对丰度进行绘图和建模，从而获得有关温度、湿度、大气环流状况以及气候变异和变化的其他方面的基本信息。过去世纪的研究将分析降水同位素场和气候联系，从太平洋海岸到北方大平原西部加拿大科迪勒拉自小冰河时代结束。这一时期（特别是过去50年）的气候详细地捕获的仪器气候记录，以及一个新开发的气候模式，可以模拟预期的降水同位素场在特定条件下。将利用过去~ 40年降水直接取样的现有同位素数据和整个世纪树木年轮纤维素分析重建的降水氧同位素组成相结合，绘制选定时间片的同位素场。仪器气候数据和重建和模型生成的降水同位素场的结合将提供一个前所未有的机会，以发展基于物理的理解空间和时间的同位素气候关系，然后可以用来解释前仪器时期的气候。对仪器使用前气候的研究将通过延长的树木年轮同位素记录，探讨气候的变异性和变化以及在过去千年的关键时刻对水资源的相关影响。最紧迫的问题之一是更好地了解中世纪导致加拿大西部大范围干旱的大气环流制度，因为气候可能正在恢复到类似状态的过程中。

The proposed research will determine how changes in the pattern and intensity of atmospheric circulation have affected the climate of western Canada over two important time-periods: (1) the past century and (2) the past millennium. The investigations are based on mapping and modelling of the relative abundances of naturally-occurring heavy isotopes of hydrogen and oxygen in precipitation, which yields fundamental information about temperature, moisture, atmospheric circulation regimes, and other aspects of climate variability and change. Studies of the past century will analyse precipitation isotope fields and climate linkages across the western Canadian Cordillera from the Pacific Coast to Northern Great Plains since the end of the Little Ice Age. The climate of this period (especially the last 50 years) is captured in detail by instrumental climate records, as well as by a newly-developed climate model that can simulate the expected precipitation isotope fields under specified conditions. Isotope fields for selected time-slices will be mapped using a combination of existing isotope data from direct sampling of precipitation over the past ~ 40 years and precipitation oxygen-isotope composition reconstructed from analysis of tree-ring cellulose over the full century. The combination of instrumental climate data and reconstructed and model-generated precipitation isotope fields will afford an unprecedented opportunity to develop physically-based understanding of spatial and temporal isotope-climate relations, which can then be used to interpret the climate of the pre-instrumental period. Studies of pre-instrumental climate will probe climate variability and change and the associated impacts on water resources at key times in the past millennium from extended tree-ring isotope records. One of the most pressing concerns is to develop better understanding of the atmospheric circulation regime that led to widespread drought across western Canada in Medieval times, because of the possibility that climate may be in the process of returning to a similar state.