Northern hemisphere lake ice cover under contemporary and future climate conditions

湖冰覆盖已被证明是气候变率和变化的有力指标。最近的研究表明，在过去的50年里，北半球（NH）的许多地方，由于冬季和春季气候条件变暖，破裂日期发生得特别早。冻融日期，以及在较小程度上的冻融日期，已被证明与0℃等温线日期的变率和趋势以及大尺度大气和海洋环流模式（遥相关）密切相关，特别是在北美西部。最近记录的过去50年的气温和冬季降水趋势以及全球气候模式预估的趋势可能对北纬地区冰盖的时间、持续时间、厚度和组成产生重大影响。反过来，这可能对北半球不同地区的能源、水和生物地球化学循环以及水生生态系统产生重要影响。在过去的50年里，湖冰覆盖是如何变化的，以及预计的21世纪气候变暖对北半球不同地区不同深度湖泊冰覆盖的可能影响是必须研究的问题，以便更深入地了解北纬地区的气候-湖泊相互作用。拟议的研究计划将寻求回答这些紧迫的问题。总体目标将是提供20世纪下半叶湖泊冰盖的时空变率和趋势与遥相关模式的nhh综合，以及湖泊冰盖对预估未来气候条件响应的合理情景。这项研究的结果将为国际极地年（IPY）期间以及国际气候变化计划（如气候与冰冻圈（CliC）、全球气候观测系统（GCOS）、综合全球观测系统(IGOS) -冰冻圈）和国际气候变化专门委员会（IPCC）等评估提供关键数据和信息。

Lake-ice cover has been shown to be a robust indicator of climate variability and change. Recent studies have demonstrated that break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere (NH) over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. Break-up dates, and to a lesser extent freeze-up dates, have been shown to be strongly related to the variability and trends in the 0oC isotherm dates as well as large-scale atmospheric and oceanic circulation patterns (teleconnections), particularly in western North America. The impacts of recently documented trends in air temperature and winter precipitation over the last five decades and those projected by global climate models could be significant on the timing, duration, thickness, and composition of ice cover at northern latitudes. This could, in turn, have an important effect on energy, water and biogeochemical cycling, and aquatic ecosystems in various regions of the NH. How lake-ice cover has changed over the last five decades, and what will likely be the impacts of projected 21st century climate warming on ice cover for lakes of various depths in different regions of the NH are questions that must be examined in order to gain a deeper understanding of climate-lake interactions at northern latitudes. The proposed research program will seek to answer these pressing questions. The overall goal will be to provide a NH synthesis of the temporal and spatial variability and trends in lake ice cover in relation to teleconnection patterns during the second half of the 20th century, and plausible scenarios of the response of lake ice cover to projected future climate conditions. Results from this research will contribute critical data and information during the International Polar Year (IPY) period as well as to international climate change programs (e.g. Climate and Cryosphere (CliC), Global Climate Observing System (GCOS), Integrated Global Observing System (IGOS) - Cryosphere) and assessments such as the International Panel on Climate Change (IPCC).