2021年冬季海洋天气评述

2021 年冬季(2021 年12 月—2022 年2 月)大气环流特征为:北半球极涡呈多极型分布,中高纬环流呈3 波型分布。位势高度距平场显示,东亚中纬度地区处于正距平区,西伯利亚脊偏强,而东亚大槽较常年同期偏弱,冷空气活动偏少、强度偏强。我国近海出现了 8 次 8 级以上大风过程, 其中冷空气大风过程4 次,冷空气和温带气旋共同影响的大风过程3 次,冷空气和台风共同影响的大风过程1 次。我国近海未出现大范围的海雾过程。西北太平洋和南海共生成 2 个热带气旋,且均达到超强台风级,其中 2122 号台风“雷伊”是历史上 12 月在南海海域达到超强台风级的 2 个台风之一,也是历史上直接袭击南沙群岛的最强台风,还是影响南海最晚的超强台风。另外,全球其他海域共生成热带气旋14 个。我国近海出现2. 0 m 以上大浪过程的天数有56 d,约占冬季总日数的62%。冬季,我国近海海域呈明显降温趋势,北部海域的降温幅度明显大于南部海域,冬季海面温度较常年整体偏高。

Winter 2021 marine weather review

The atmospheric circulation characteristics in the winter of 2021 (from December 2021 toFebruary 2022)are as follows. The polar vortex in the Northern Hemisphere is distributed in a multipoletype and the circulation shows a three-wave pattern in middle and high latitudes. The geopotential heightanomaly field at 500 hPa shows that the mid-latitude region of East Asia presents positive anomaly,theridge over Siberia is stronger,while the East Asian trough is weaker than that in normal years,so thecold air activity is less and its intensity is stronger. There are 8 gale processes (above 8-grade)overoffshore areas of China,among which 4 processes are influenced by cold air,three jointly by cold air andextratropical cyclones,and one jointly by cold air and tropical cyclone. There is no large-scale sea fogprocess in the coastal waters of China. There are two tropical cyclones generated over western NorthPacific and the South China Sea,and both of them develop into super typhoons. Among them,TyphoonRai (2021)is one of the two typhoons to reach the scale of super typhoon in the South China Sea inDecember in history. It is also the strongest tropical cyclone to hit the Nansha Islands directly in history and the latest super typhoon to affect the South China Sea. In addition,14 tropical cyclones are generatedin other sea areas around the world. There are 56 days with rough sea wave processes above 2.0 m overoffshore areas of China,accounting for about 62% of the total winter days. In winter,the sea surfacetemperature shows an obvious cooling trend in offshore areas of China,and the cooling amplitude of thenorthern sea areas is significantly greater than that of the southern sea areas. The sea surface temperaturein winter is generally higher than that of normal years.