Collaborative Research: Marine Climate and Relative Sea Level Across Central Beringia

白令海峡是白令海峡分隔的广阔地区。富含营养物质的北太平洋水沿白令海东部大陆坡向北流动，穿过大陆架，进入楚科奇海，维持高地表水。太平洋水域还贡献了大约30%的北冰洋淡水预算（约占河流贡献的一半），这有助于维持北极盐跃层、北极海冰，并调节北大西洋地区的气候。末次盛冰期（LGM），海平面下降125米，白令陆桥面积大得多，太平洋和北冰洋相隔近1000公里。白令陆桥的气候更加均匀，因为海洋离得很远。由于缺乏周围海洋的数据，海洋在控制白令陆桥气候方面的确切作用尚不清楚。相对海平面的历史所知甚少，但由于构造和可能的冰川-上升作用，相对海平面很可能与上升海平面不同。海冰范围、温度和盐度等海面条件可能通过反照率效应、热交换和湿度影响气候，但在白令海和楚科奇海几乎没有这些特性的高分辨率替代数据。为了将白令海峡的海洋和陆地领域联系起来，首席研究员将在白令海和楚科奇海参与重力、活塞和振动测量的实地项目，以开发白令海中层海洋通风的高分辨率记录；2)白令海和楚科奇海的海洋表面温度、盐度、海冰范围和冰山流量历史；白令海峡地区自LGM以来的相对海平面。这些目标与1999年10月美国国家科学基金会主办的关于“评估过去2万年来北极水深变化和淡水输入对大陆架和海洋环流的影响”的研讨会的主题密切相关。

AbstractOPP-99-12122KeigwinOPP-00-02643Brigham-GretteThe broad region of Beringia is separated by the Bering Strait. North Pacific waters rich in nutrients flow northward along the eastern Bering Sea continental slope, across the shelf and into the Chukchi Sea, sustaining high surface water. The Pacific waters also contribute about 30 percent of the Arctic Ocean's fresh water budget (about half of the river's contribution) which helps maintain the Arctic halocline, Arctic sea ice, and regulates climate in the North Atlantic region. During the last glacial maximum (LGM), sea level was lowered by 125 meters, Beringia was much larger and the Pacific and Arctic Oceans were separated by nearly 1000 kilometers. Beringian climate was more uniform because the sea was so distant.The exact role of the ocean in controlling Beringian climate is unknown because of the lack of data on the surrounding seas. The history of relative sea level is poorly known, but is likely to have differed from eustatic sea level because of tectonic and possible glacio-eustatic effects. Sea surface conditions such as ice extent, temperature, and salinity are likely to influence the climate through albedo effects, heat exchange, and humidity, but there are almost no high-resolution proxy data for these properties in the Bering and Chukchi Seas. To link the marine and terrestrial realms in Beringia, the Principal Investigators will participate in a field program of gravity, piston and vibracoring in the Bering and Chukchi Seas to develop high resolution records of 1) intermediate ocean ventilation in the Bering Sea; 2) surface ocean temperature, salinity, sea ice extent, and history of iceberg discharge in both the Bering and Chukchi Seas; and 3) relative sea level in the Bering Strait region since the LGM. These objectives are closely aligned with the theme of the October 1999 NSF-sponsored workshop on "Assessing Impacts of Arctic Bathymetry Changes and Fresh Water Inputs on Shelf and Ocean Circulation for the Past 20,000 Years."