2017年秋季海洋天气评述

2017年秋季（9—11月）大气环流特征为：北半球环流形势，极涡呈偶极型分布，中高纬西风带呈4波型分布，且强度较夏季增强；9—10月，副热带高压明显偏西，强度接近常年，热带气旋活动频繁；中高纬度西风带较为平直，槽脊活动不明显；11月，经向环流增大，冷空气势力增强。我国近海海域主要有14次8级以上大风过程，其中热带气旋大风有9次，冷空气大风有11次，两者共同影响下的大风过程7次。有24次2 m以上的大浪过程。未出现雷暴大风和大范围的海雾过程。期间，西北太平洋和南海共生成11个热带气旋，其他海域共有热带气旋18个，分别为：北大西洋9个、东太平洋7个、印度洋2个。海表温度整体呈下降趋势。

Autumn 2017 marine weather review

The general atmospheric circulation in the northern hemisphere in autumn (September-November) 2017 is characterized by the dipole polar vortex and 4-wave mid-high latitude westerly belt, which is stronger than that in summer. From September to October, the subtropical high is located abnormally westward with intensity close to normal, tropical cyclones are active, and the westerly belt is straighter without significant ridge and trough. In November, cold air activities are intensified due to the enhanced meridional circulation. In autumn 2017, there are mainly 14 strong winds (above 8-grade) processes in China''s inshore areas, including 9 related to cyclones, 11 generated by cold airs, and 7 under the both. There are also 24 rough wave (above 2 m) processes. In this season, there is no thunderstorm induced gale or large-scale sea fog process. In the Northwest Pacific and the South China Sea, there are 11 typhoons, while 18 tropical cyclones occurred in other oceans:9 in the North Atlantic, 7 in the eastern Pacific,and 2 in the India ocean. The sea surface temperature has a overall trend of decrease.