2020年夏季海洋天气评述

2020年夏季（6—8月），北半球极涡呈现明显的单极型分布，极涡主体位于北极圈内，中心偏向东半球，中高纬环流呈现4波型分布。6—7月，西太平洋副热带高压较常年平均偏强，且位置偏西偏南，不利于热带气旋活动。2020年夏季共有8个热带气旋在西北太平洋和南海生成，其中7月没有热带气旋生成。除西北太平洋和南海之外，其他热带洋面另有20个热带气旋生成，其中北大西洋11个，东太平洋8个，北印度洋1个。受偏南暖湿气流的影响，我国北方海域多海雾天气。同时受入海气旋活动影响，多海上大风过程。夏季近海海域共出现了7次比较明显的海雾过程，其中6月3次，7月1次，8月3次。大风过程出现了10次，2次由热带气旋影响，7次与入海气旋活动有关。发生2 m以上的大浪过程12次，6—8月分别出现了4次、5次和3次。

Summer 2020 marine weather review

The main characteristics of the general atmospheric circulation in summer 2020 (from June to August) are as follows. The polar vortex is characterized by a monopole pattern in the Northern Hemisphere, which centers in the Arctic Circle toward the Eastern Hemisphere. The circulations in the middle and high latitudes present a 4-wave mode. Due to the anomalously strong western Pacific subtropical high that lies westward and southward, there are fewer tropical cyclone activities in June and July than in normal years. There are totally 8 tropical cyclones generated over western North Pacific and the South China Sea in this summer, while none is generated in July. Except for western North Pacific and the South China Sea, there are 20 tropical cyclones in other oceans, including 11 in the North Atlantic, 8 in the East Pacific, and one in the North Indian Ocean. The warm and moist southerly winds bring about several sea fog events in the northern seas, and there are more sea gales under the impacts of the cyclones moving into the sea. There are 7 obvious sea fog events over offshore areas in the summer, including three in June, one in July, and three in August. There are 10 gale processes over offshore areas, among which two are related to tropical cyclones and 7 are caused by extratropical cyclones. Twelve rough sea wave events above 2 m occur over offshore areas with 4, 5 and three in June, July, and August, respectively.