Abstract：
Lake Surface Water Temperature (LSWT) influences critical bio-geological processes in lake ecosystems, and there is growing evidence of rising LSWT over recent decades worldwide and future shifts in thermal patterns are expected to be a major consequence of global warming. At a regional scale, assessing recent trends and anticipating impacts requires data from a number of lakes, but long term in situ monitoring programs are scarce, particularly in mountain areas. In this work, we propose the combined use of satellite-derived temperature with in situ data for a five-year period (2017-2022) from 5 small (<0.5km2) high altitude (1880-2680 masl) Pyrenean lakes. The comparison of in situ and satellite-derived data in a common period (2017-2022) during the summer season showed a notably high (r = 0.94, p < 0.01) correlation coefficient, indicative of a robust relationship between the two data sources. The root mean square errors ranged from 1.8 °C to 3.9 °C, while the mean absolute errors ranged from 1.6 °C to 3.6 °C. We applied the obtained in situ-satellite eq. (2017-2022) to Landsat 5, 7 and 8/9 data since 1985 to reconstruct the summer surface temperature of the five studied lakes with in situ data and to four additional lakes with no in situ monitoring data. Reconstructed LSWT for the 1985-2022 showed an upward trend in all lakes. Moreover, paleolimnological reconstructions based on sediment cores studies demonstrate large changes in the last decades in organic carbon accumulation, sediment fluxes and bioproductivity in the Pyrenean lakes. Our research represents the first comprehensive investigation conducted on high mountain lakes in the Pyrenees that compares field monitoring data with satellite-derived temperature records. The results demonstrate the reliability of satellite-derived LSWT for surface temperatures in small lakes, and provide a tool to improve the LSWT in lakes with no monitoring surveys.
摘要：
湖泊地表水温度（LSWT）影响湖泊生态系统中的关键生物地质过程，越来越多的证据表明，近几十年来，全球范围内的LSWT上升，未来的热模式变化预计将是全球变暖的主要后果。在区域范围内，评估近期趋势和预测影响需要来自多个湖泊的数据，但是长期的现场监测项目很少，尤其是在山区。在这项工作中,我们建议结合使用5个小型（<0.5km2）高海拔（1880-2680masl）比利牛斯湖的五年（2017-2022年）的现场数据。夏季常见时期（2017-2022年）的原位和卫星衍生数据的比较显示出明显较高的相关系数（r=0.94，p<0.01），表示两个数据源之间的稳健关系。均方根误差范围为1.8°C至3.9°C，而平均绝对误差范围为1.6°C至3.6°C。我们应用了获得的原位卫星方程。（2017-2022）自1985年以来的Landsat5、7和8/9数据，以使用原位数据重建五个研究湖泊的夏季表面温度，并重建四个没有原位监测数据的其他湖泊。1985-2022年重建的LSWT在所有湖泊中均呈上升趋势。此外，基于沉积物岩心研究的古火山学重建表明，在过去的几十年中，有机碳积累发生了巨大变化，比利牛斯湖的沉积物通量和生物生产力。我们的研究代表了对比利牛斯山脉高山湖泊进行的首次全面调查，该调查将野外监测数据与卫星衍生的温度记录进行了比较。结果证明了卫星衍生的LSWT对小湖泊表面温度的可靠性，并提供了一种在没有监测调查的情况下改善湖泊LSWT的工具。
