During the Arctic summer, sea fog occurs very frequently and its low visibility poses a significant threat to the safety of Arctic shipping routes. However, due to sparse observations, the understanding of Arctic sea fog mostly remains limited to regional analyses or case studies, and the overall characteristics of Arctic sea fog and how it will change under global warming remain unclear. This study analyzes Arctic sea fog based on observations and numerical models, leading to the following conclusions:

1. Previous studies speculated that sea ice is the dominant factor influencing fog frequency based on the observation that open-water fog frequency is lower than in sea ice areas. However, this study finds that, even within ice-covered regions, fog frequency in the Eurasian ice area is approximately twice that of the North American ice area, and reveals that air temperature is the dominant factor influencing fog frequency.
2. In terms of trends, this study reconstructs long-term sea fog data through numerical simulations and finds that in regions with heavy sea ice, Arctic warming increases atmospheric humidity, promoting an increase of sea fog. In contrast, in areas with less sea ice, warming weakens atmospheric stability, thereby suppressing sea fog. These two competing mechanisms explain the complex changes in Arctic sea fog.
3. In terms of impacts, this study demonstrates that low visibility caused by sea fog can extend the total sailing time of Arctic shipping routes by about three days, highlighting the non-negligible influence of sea fog on designing shipping routes.

Arctic fog,climate change,Moisture,Atmospheric Stability,Arctic shipping route