The role of the South China Sea in gererating acoustic gravity waves resulted in meteotsunamis over the East China Sea

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Monday, 5 January 2015
Daiki Ito, Hiroshima Institude of Technology, Hiroshima, Japan; and K. Tanaka

Handout (4.4 MB)

Much of meteotsunamis caused during the season between November and next April over the East China Sea. It has been revealed that the source of the pressure disturbance, driving the ocean long waves, were generated in the middle-east and southeast China region by mixing lifted moist air mass from South China Sea and dry air mass in the middle troposphere below subtropical jets. The present study is aimed to reveal the role of the air-sea interaction over the South China Sea in providing the moist air mass to generate pressure disturbance over the East China Sea.

In winter season, the cold air flow near the sea surface layer came from land area from South China or the cold sea water current along the coastal area of China. The input of the cold air mass from north of the South China Sea has generated anomalously high evaporation, with the magnitude as high as that of the middle summer. The thickness of lower troposphere (e.g., between 1000 hPa and 850 hPa isobaric surface) oscillated with the period of 5 - 10 days, by pumping of the moisture from sea surface evaporation. It is more easy to expand the moist air vertically over the South China Sea horizontally blocked by surrounded land areas. The horizontal divergence of the moist air toward the land area of South China occurred throughout the expansion of the lower troposphere.

A series of the moisture transport from South China Sea to land area of South China was seen within several days before meteotsunami event recorded in the west Kyushu, Japan.