Abstract Changes in the ice phenology, seasonal temperature and extreme events are consistent evidence of climate change effect on lakes. In this study, we analyzed multiannual variability, determined long-term trends and detected changes in the frequency of extreme events in the surface water temperature (LSWT) of Lake Peipsi (Estonia/Russia) for nearly seven decades (1950-2018) and aimed to trace how the LSWT responded to the climate change. Dynamic water temperature parameters were calculated using the smoothed water temperature curve fitted to daily water temperatures. Our results showed that, although the average LSWT did not increase significantly on an annual basis since 1950 it rose rapidly in the winter season during the last decade (∼ +0.5 °C). Ice formation exhibited a marked (∼15 days) delay since 2007 resulting in a longer open water period. Extreme LSWT events did not occur more frequently. We noticed however significant fluctuating in winter LSWT in time series, starting from 2007 and also causing an increase in stochasticity. The consequences of the on-going winter warming and changes of ice cover phenology are expected to be crucial for Lake Peipsi ecosystem functioning and impact on lake biota, especially temperature-sensitive native fishes.

中文翻译：

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欧洲第四大湖地表水温参数化和长期趋势显示冬季近期迅速变暖

摘要 冰物候、季节性温度和极端事件的变化是气候变化对湖泊影响的一致证据。在这项研究中，我们分析了近七年（1950 年至 2018 年）佩西湖（爱沙尼亚/俄罗斯）地表水温 (LSWT) 极端事件频率的多年变化、长期趋势和变化，并旨在追踪 LSWT 如何应对气候变化。使用适合日常水温的平滑水温曲线计算动态水温参数。我们的结果表明，尽管自 1950 年以来平均 LSWT 没有每年显着增加，但在过去十年的冬季（~+0.5°C）迅速增加。自 2007 年以来，冰的形成表现出明显的（~15 天）延迟，导致更长的开放水域期。极端 LSWT 事件没有更频繁地发生。然而，我们注意到从 2007 年开始，冬季 LSWT 在时间序列中出现了显着波动，并且也导致了随机性的增加。持续的冬季变暖和冰盖物候变化的后果预计对佩皮湖生态系统的功能和对湖泊生物群的影响至关重要，尤其是对温度敏感的本地鱼类。