The basin water of a sill fjord is renewed intermittently, when the density of the water at sill level in the ocean outside the fjord is high enough for it to sink down to the bottom of the fjord. How often the basin water is renewed, the renewal frequency, depends on how fast diffusion and mixing cause the density in the basin to decrease and on the variability of the density in the ambient ocean. Here, we suggest a statistical approach to investigate how a trend – e.g. imposed by global warming – in the ambient ocean density will affect the renewal frequency of a sill fjord. Negative ambient trends that are large compared to the rate at which density decreases the fjord will have large impact on the renewal frequency. It is shown that the observed negative trend in the annual maximum density at a hydrographical station near the Norwegian fjord Masfjorden, is very likely to have reduced the renewal frequency and increased the length of the stagnation period compared to pre-trend conditions. Negative trends in the annual maximum density since 1990 are observed at six out of eight longterm hydrographical stations along the Atlantic Norwegian coast, suggesting that the deep water renewal frequency in many Norwegian fjords has been reduced during the last 30 years.

当峡湾外海中的基石水位的水密度足够高到足以沉入峡湾的底部时，峡湾的盆地水会间歇性地更新。流域水的更新频率，更新频率取决于扩散和混合的速度如何导致流域密度降低，以及周围海洋密度的变化性。在这里，我们建议一种统计方法来研究周围海洋密度的变化趋势（例如，由全球变暖引起的变化）将如何影响窗台峡湾的更新频率。与密度降低峡湾的速率相比，较大的负环境趋势将对更新频率产生很大影响。结果表明，与趋势前条件相比，在挪威峡湾马斯峡湾附近的水文站观测到的年最大密度的负趋势很可能降低了更新频率，并延长了停滞期的时间。自1990年以来，在大西洋挪威海岸的八个长期水文站中有六个观测到的年最大密度呈负趋势，这表明在过去30年中，许多挪威峡湾的深水更新频率有所减少。