Ice Core Reconstruction of North Pacific Climate Variability and Environmental History from the Bona-Churchill Ice Field, Alaska

OPP-00-99311汤普森首席调查员将从山间冰层取回冰芯。博纳和Mt.丘吉尔，位于阿拉斯加东南部的兰格尔山脉。冰芯记录将填补该区域高分辨率气候历史上的一个重大空白，并将补充和扩展基于树木年轮的气候记录。这些记录将对其他北极冰场的高分辨率冰芯历史做出重要贡献，这些冰场包括格陵兰岛、斯瓦尔巴特群岛、加拿大北极高地、风穹冰帽(Franz Josef Land，俄罗斯北极)和格陵兰。这些极地记录是全球冰芯记录套件的一部分，其中包括从西藏、南美洲和非洲的七个低纬度、高海拔地点提取的冰芯记录。这些岩心为确定第四纪气候变化的主要驱动因素和确定冰川时代气候事件的全球同步性的持续努力贡献了关键的低纬替代气候历史。目前，还没有来自阿拉斯加的高质量冰芯记录，因此这些冰芯应该会提供至关重要的新见解。太平洋盆地东北侧缺乏高分辨率的气候历史，这是促进我们对太平洋地区动态状态及其全球联系的快速和最近变化的理解的主要障碍。特别令人感兴趣的是：1)过去30年的变暖，似乎在热带、亚热带、北美西北部和亚洲北部的高海拔地区被放大；2)1976-77年太平洋盆地气候动态的最新阶跃变化；3)最近发现的类似于ENSO的中纬度气候变化的性质，可能源于热带太平洋。实地考察计划将包括地球物理和地表研究，旨在选择COL上两个高分辨率、保存完好的500米冰芯记录的最佳地点。实验室对可溶和不溶气溶胶浓度的测量结果将揭示干旱和湿润时期以及相对风暴强度。氧同位素分析应提供该地区温度历史和过去大气环流模式的替代物。高的年累积和冷的年平均温度是物理化学记录中厚实和保存完好的年信号的良好指标，这将允许以过去1000年的年分辨率进行出色的时间控制。完整的记录应该至少追溯到5000年前。必须从全球分散的长期替代气候记录提供的视角来评估近期气候和环境变化的重要性。将这些记录从一极连接到另一极可以评估这些气候变化的全球性质，并确定高纬度和热带之间的关键联系，在这些联系中，全球热源的变化可以引发气候系统的全球范围的变化。

AbstractOPP- 00-99311ThompsonThe Principal Investigators will retrieve ice cores from the col between Mt. Bona and Mt. Churchill, located in Wrangell Mountains, southeastern Alaska. The ice core records will fill a significant void in the high resolution climate history of this region and will complement and extend the tree ring-based climate records. These records will be an important contribution to the suite of high resolution ice core histories from other north polar ice fields including, Greenland, Svalbard, the High Canadian Arctic the Windy Dome Ice Cap (Franz Josef Land, Russian Arctic) and Greenland. These polar records are part of a global suite of ice core records including those retrieved from seven lower latitude, high altitude sites in Tibet, South America, and Africa. These cores have contributed critical low-latitude proxy climate histories to the continuing efforts to identify the major drivers of Quaternary climate change and to determine the global synchronicity of glacial-age climate events. Currently, there are no high quality ice core records from Alaska, so these cores should provide critical new insights. The paucity of high resolution climate histories from the northeastern side of the Pacific Basin is a major obstacle to advancing our understanding of the rapid and recent changes in the dynamic state of the Pacific region and its global connections. Of particular interest are: 1) the warming of the last 30 years that appears to be amplified at high elevations in the tropics and subtropics and in northwestern North America and northern Asia; 2) the most recent 'step' change in the dynamics of the Pacific Basin climate regime in 1976-77; and 3) the nature of recently identified multi-decadal ENSO-like mid-latitude climate variability that may have its roots in the tropical Pacific.The field program will include geophysical and surface studies designed to select the best site on the col for recovery of two high resolution, well-preserved ice core records to about 500 meters. The results from laboratory measurements of soluble and insoluble aerosol concentrations will reveal drought and wet periods and relative storm intensities. Oxygen isotope analyses should provide a proxy for the temperature history and past atmospheric circulation patterns in this area. The high annual accumulation and cold mean annual temperatures are good indicators for thick and well preserved annual signals in the physical and chemical records that will allow excellent time control with annual resolution for the last 1000 years. The complete record should extend back at least 5,000 years. The significance of recent climatic and environmental variations must be evaluated from a perspective provided by a globally dispersed, long-term proxy climate records. Linking these records from pole to pole allows assessment of the global nature of these climatic variations and identification of critical linkages between the higher latitudes and the tropics where changes in the global heat source can trigger global-scale changes in the climate system.