Collaborative Research: The role of Ice in the response of Large Lakes to a Changing Climate

合作研究：冰在大型湖泊对气候变化的响应中的作用

• 批准号: 0825633
• 负责人: Jay Austin
• 金额: $ 61.1万
• 依托单位: University of Minnesota Duluth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825633&HistoricalAwards=false
• 关键词: Collaborative; Research; role; Ice; response

The long-term response of large lakes to climate change is not well understood. Recent observational results have shown that winter ice cover plays a vital and previously underappreciated role in determining thermal conditions the following summer; the concentration of high albedo ice determines the timing of the spring overturn, which in turn affects summer temperatures. A long-term trend towards lesser ice cover in Lake Superior is causing a sustained and more effective warming season that is contributing to a rise in summer lake temperatures in significant excess of the rise in air temperature. However, the role that ice plays in this phenomenon and the ability to predict the thermal response of the lake to climate change is poorly understood. In addition, the thermal response of the lake to winter ice cover is critical to its carbon cycle, because temperature is perhaps the single most important determinant of biogeochemical reaction rates. Rates such as nutrient uptake rates by phytoplankton and bacterial respiration rates work in synchrony to regulate the lake carbon cycle. Nevertheless, little is known about what effect steadily rising lake temperatures may have on the long-term stability of biochemical cycles within large lakes. This project will fill in these gaps in knowledge and to gain a fundamental understanding of the role of ice in determining the full annual and interannual cycles of temperature and carbon in large lakes. The following questions that pertain to Lake Superior?s physics and biogeochemistry will be addressed: 1) What is primarily responsible for setting the amount of ice formation? 2) What role does the spatial and temporal variability of ice formation play in determining lake-wide summer conditions? 3) What are the trends in mixed layer depth? 4) Are increased temperatures and reduced ice cover playing a role in the long-term mass balance of the lake, and contributing to the general trend of lower water over the last few decades? 5) How much ?information? regarding heat and carbon, if any, is passed from one year to the next? 6) What is the impact of a progressively earlier ice melt, higher summer temperatures, and stronger thermal stratification on biological production and carbon cycle? The project will improve our understanding of lake levels, a significant factor to the shipping industry. The unprecedented dataset will be available to a variety of lake modelers. Expertise in ice and biogeochemical modeling will also be broadened.

大型湖泊对气候变化的长期反应尚不清楚。最近的观测结果表明，冬季冰盖在决定次年夏季的热条件方面发挥着至关重要的作用，但之前却被低估了。高反照率冰的浓度决定了春季翻转的时间，进而影响夏季的气温。苏必利尔湖冰盖减少的长期趋势正在导致持续且更有效的变暖季节，从而导致夏季湖泊温度的上升远远超过气温的上升。然而，人们对冰在这种现象中所扮演的角色以及预测湖泊对气候变化的热响应的能力知之甚少。此外，湖泊对冬季冰盖的热响应对其碳循环至关重要，因为温度可能是生物地球化学反应速率的最重要的决定因素。浮游植物的养分吸收率和细菌呼吸率等速率同步调节湖泊碳循环。然而，人们对湖泊温度稳步上升可能对大型湖泊内生化循环的长期稳定性产生什么影响知之甚少。该项目将填补这些知识空白，并从根本上了解冰在确定大型湖泊温度和碳的完整年度和年际循环中的作用。将解决与苏必利尔湖物理和生物地球化学有关的以下问题： 1) 决定冰形成量的主要因素是什么？ 2）冰形成的时空变化在决定全湖夏季条件方面发挥什么作用？ 3）混合层深度的趋势是什么？ 4）温度升高和冰盖减少是否对湖泊的长期质量平衡产生了影响，并导致了过去几十年来水位下降的总体趋势？ 5）有多少？信息？关于热量和碳，如果有的话，是从一年到下一年的吗？ 6) 冰雪融化逐渐提前、夏季气温升高以及热分层加剧对生物生产和碳循环有何影响？该项目将增进我们对湖泊水位的了解，而湖泊水位是航运业的一个重要因素。这个前所未有的数据集将可供各种湖泊建模者使用。冰和生物地球化学建模方面的专业知识也将得到扩展。