Atlantic Water is a major contributor to the largest zonal variability in ocean properties and air-sea-ice interaction in the Nordic Seas and the European Arctic. Climate change has amplified warming and intensified extreme events, in both the ocean and the atmosphere, with severe implications for the marine environment. Here, we present our long-term (1999–2020) hydrographic observations from the shelf south-west of Spitsbergen, focusing on the extent of Atlantic and Arctic waters, and we examine their impact on the water masses in Hornsund fjord. Our results show an 8% y⁻¹ increase of the Atlantic Water volume fraction on the shelf during the period 1999–2020, especially noticeable in the last decade. Although this does not imply a significant increase in the amount of waters of the Atlantic origin in the fjord, the greater role of Atlantic Water is attributed to changes in water properties (volume and temperature) of the upper water layer in Hornsund. The strong controlling effect of Arctic Water, transported by the Spitsbergen Polar Current, on the salinity of the fjord surface and intermediate layers is helping to preserve the Arctic character of Hornsund. Nevertheless, ongoing Atlantification of the Nordic and Barents Seas may reduce supply of Arctic Water, thereby diminishing the role of the Spitsbergen Polar Current as the agent mitigating the impact of Atlantic Water on the west Spitsbergen fjords. In the future, this may contribute to the disappearance of the gradation in hydrographic conditions currently observed in the fjords along the west coast of Spitsbergen.

大西洋水是造成北欧海洋和欧洲北极地区海洋特性和空气-海-冰相互作用的最大带状变异的主要因素。气候变化加剧了海洋和大气中的变暖和极端事件，对海洋环境产生了严重影响。在这里，我们展示了我们对斯匹次卑尔根岛西南大陆架的长期（1999-2020 年）水文观测，重点关注大西洋和北极水域的范围，并研究它们对 Hornsund 峡湾水团的影响。我们的结果显示 8% y ^-11999 年至 2020 年期间大陆架上大西洋水体积分数的增加，在过去十年中尤为明显。尽管这并不意味着峡湾中源自大西洋的水域数量显着增加，但大西洋水的更大作用归因于 Hornsund 上部水层的水特性（体积和温度）的变化。由斯匹次卑尔根极地流输送的北极水对峡湾表面和中间层的盐度的强大控制作用有助于保护霍恩松德的北极特征。尽管如此，北欧和巴伦支海正在进行的大西洋化可能会减少北极水的供应，从而削弱斯匹次卑尔根极地流作为减轻大西洋水对斯匹次卑尔根峡湾西部影响的代理的作用。