《海洋预报》| 夏季旋链角毛藻赤潮生消的海气动力机制分析

摘要：针对温州海域夏季赤潮发生机制不明、预警难度大的问题，基于岸基站实测数据、卫星遥感反演资料和再分析数据集，分析了2023年8月一次典型旋链角毛藻赤潮前后水文、气象和水质因素的变化，探究了夏季温州海域赤潮发生和消亡所需的海洋与大气环流动力机制。结果表明：由于夏季北上台风引发大气环流结构调整，形成强降水和上升流过程，导致陆源径流输入剧增、低温区北延，温州近岸海域水温、盐度和营养盐发生显著波动，进而诱发夏季硅藻赤潮。其中温州主要流域累积降水量达到150 mm并达到峰值，赤潮区邻近海洋站盐度单日降幅超过2且数值低于30，以及水质锋面离岸距离大于30 km等，是预测夏季旋链角毛藻赤潮发生的重要指征。夏季赤潮消亡与外部强迫动力环境紧密相关，当外部海气波动过程消失后，相应的营养盐、水温、盐度指标恢复正常，赤潮过程结束。

关键词：夏季 赤潮 旋链角毛藻 台风 早期预警

Abstract：Based on measured data from shore-based stations, satellite remote sensing data, and reanalysis data, changes of hydrological, weather, and water quality factors during the Chaetoceros curvisetus red tide in August 2023 were analyzed, and the involved oceanic and atmospheric dynamical mechanisms in the occurrence and extinction of the red tide in the Wenzhou coastal areas were investigated. The results show that: Under the influence of typhoons, changes in atmospheric circulation trigger heavy precipitation and oceanic upwelling, leading to an increase in runoff and northward extension of the low ocean temperature area. Then, the significant fluctuation of water temperature, salinity and nutrient salts in the Wenzhou coastal areas leads to the occurrence of diatom red tides in the summer. Important indicators of red tides in summer include: cumulative precipitation in Wenzhou's major watersheds reaches 150 mm and a peak, salinity at a representative station decreases by 2 and is lower than 30 on a single day, and the distance between the water quality front and the coastline is larger than 30 km, etc. The extinction of red tide in summer is closely related to the external dynamical environment. When the external ocean-atmosphere fluctuation disappeared, and the nutrient salts, water temperature and salinity indexes returned to normal, the red tide process died out.

Key words：summer; red tide; Chaetoceroscurvisetus; typhoon; early warning

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