The sea surface temperature (SST) front in the Gulf Stream (GS) extension region is important to synoptic variations in atmosphere. In winter, large amounts of heat and moisture are released from the SST front, modulating the baroclinicity and humidity of the atmosphere, which is important for extratropical cyclones and atmospheric rivers (ARs). In this study, the variation of SST in the North Atlantic in winters since 1981 is investigated using satellite and reanalysis datasets, and a 23-year (1997 to 2019) warming trend of SST in the GS extension region is detected. The increase of SST is mainly distributed along the SST front, with more than 2 °C warming and a northward shift of the SST gradient from 1997 to 2019. Connected with the SST warming, significant increases in turbulent heat flux and moisture release into the atmosphere were found along the ocean front. As a result, baroclinic instability, upward water vapor flux and AR occurrence frequency increased in recent decades. Meanwhile, there was an increase in extreme rainfall along with the increase in AR landfalling on continental Western Europe (especially in the Iberian Peninsula and on the northern coast of the Mediterranean Sea).

中文翻译：

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墨西哥湾流扩展区近几十年来的海温上升及其对大气河流的影响

墨西哥湾流（GS）延伸区的海面温度（SST）前沿对于大气的天气变化很重要。在冬季，SST前端释放大量的热量和水分，从而调节了大气的斜压和湿度，这对于温带气旋和大气河流（AR）至关重要。在这项研究中，使用卫星和再分析数据集调查了1981年以来北大西洋冬季SST的变化，并发现了GS扩展区SST的23年（1997年至2019年）变暖趋势。SST的增加主要分布在SST前沿，温度升高超过2°C，并且从1997年到2019年SST梯度向北移动。在沿海地区，湍流通量和向大气中的水分释放量显着增加。结果，近几十年来斜压不稳定，向上的水蒸气通量和AR发生频率增加。同时，在西欧大陆（特别是在伊比利亚半岛和地中海北部海岸），极端降雨伴随着AR登陆量的增加而增加。