A Study on a Persistent Sea Fog Event in Zhoushan from April 9 to 12, 2025

本文基于自动站资料和ERA5再分析资料，对2025年4月9~12日舟山一次持续性海雾事件进行了综合分析。研究发现，该事件呈现多次生成、消散、再生成的复杂过程，其中第三次过程影响最大，低能见度站点占比达75%，能见度多在200米以下。环流背景复杂，弱波动、均压场、倒槽及低压系统等先后影响，导致地面偏南风和东南风盛行，利于海上水汽输送。四次过程均存在深厚逆温层，利于水汽在近地层积累，促使海雾过程反复发生。Based on automatic weather station data and ERA5 reanalysis data, this study conducts a comprehensive analysis of a persistent sea fog event in Zhoushan from April 9 to 12, 2025. The results show that the event exhibited a complex process of multiple occurrences, dissipation, and re-occurrences. The third process had the most significant impact, with 75% of the stations experiencing low visibility and most visibilities below 200 meters. The circulation background was complex, with weak troughs in the westerly airflow, quasi-stationary pressure fields, inverted troughs, and low-pressure systems successively affecting the region. These conditions led to prevailing southerly and southeast winds, which facilitated the transport of abundant water vapor from the sea. All four processes featured a deep inversion layer, which facilitated the accumulation of water vapor in the near-surface layer and contributed to the persistence of dense fog.