Abstract Lakes provide enormous economic, recreational, and aesthetic benefits to citizens. These ecosystem services may be adversely impacted by climate change. In the Twin Cities Metropolitan Area of Minnesota, USA, many lakes have been at historic low levels and water augmentation strategies have been proposed to alleviate the problem. White Bear Lake (WBL) is a notable example. Its water level declined 1.5 m during 2003–2013 for reasons that are not fully understood. This study examined current, past, and future lake evaporation to better understand how climate will impact the water balance of lakes within this region. Evaporation from WBL was measured from July 2014 to February 2017 using two eddy covariance (EC) systems to provide better constraints on the water budget and to investigate the impact of evaporation on lake level. The estimated annual evaporation losses for years 2014 through 2016 were 559 ± 22 mm, 779 ± 81 mm, and 766 ± 11 mm, respectively. The higher evaporation in 2015 and 2016 was caused by the combined effects of larger average daily evaporation and a longer ice-free season. The EC measurements were used to tune the Community Land Model 4 – Lake, Ice, Snow and Sediment Simulator (CLM4-LISSS) to estimate lake evaporation over the period 1979–2016. Retrospective analyses indicate that WBL evaporation increased during this time by about 3.8 mm year −1 , which was driven by increased wind speed and lake-surface vapor pressure gradient. Using a business-as-usual greenhouse gas emission scenario (RCP8.5), lake evaporation was modeled forward in time from 2017 to 2100. Annual evaporation is expected to increase by 1.4 mm year −1 over this century, largely driven by lengthening ice-free periods. These changes in ice phenology and evaporation will have important implications for the regional water balance, and water management and water augmentation strategies that are being proposed for these Metropolitan lakes.

中文翻译：

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温带封闭盆地湖泊的蒸发及其对现在、过去和未来水位的影响

摘要 湖泊为市民提供了巨大的经济、娱乐和审美效益。这些生态系统服务可能会受到气候变化的不利影响。在美国明尼苏达州的双城都会区，许多湖泊处于历史低位，并提出了增水策略来缓解这一问题。白熊湖 (WBL) 就是一个显着的例子。其水位在 2003 年至 2013 年期间下降了 1.5 m，原因尚不完全清楚。这项研究检查了当前、过去和未来的湖泊蒸发量，以更好地了解气候将如何影响该地区湖泊的水平衡。从 2014 年 7 月到 2017 年 2 月，使用两个涡流协方差 (EC) 系统测量了 WBL 的蒸发量，以更好地约束水预算并研究蒸发对湖泊水位的影响。2014 年至 2016 年估计的年蒸发损失分别为 559±22 毫米、779±81 毫米和 766±11 毫米。2015 年和 2016 年蒸发量较高是由于日平均蒸发量较大和无冰季节较长的综合影响所致。EC 测量值用于调整社区土地模型 4 – 湖泊、冰、雪和沉积物模拟器 (CLM4-LISSS)，以估计 1979 年至 2016 年期间的湖泊蒸发量。回顾性分析表明，在此期间，WBL 蒸发量增加了约 3.8 mm year -1 ，这是由风速和湖面水汽压力梯度增加所驱动的。使用一切照旧的温室气体排放情景 (RCP8.5)，对 2017 年至 2100 年的湖泊蒸发进行了建模。预计本世纪年蒸发量将增加 1.4 毫米 -1 年，主要是由于无冰期延长。冰物候和蒸发的这些变化将对区域水平衡以及为这些大都会湖泊提出的水管理和增水策略产生重要影响。