A Preliminary Study On The Influence Of Cold Airs On The Sea Surface Temperature In Taiwan Strait

Cold air is the air that causes air temperature decrease when it crosses someplaces. It has a big influence on coastal facilities, marine culture, offshore operationsand the marine ecological environment. Therefore, there is important practical andscientific significance for us to study cold air and its influence on the sea. This paperwill census the cold airs in the winter-half year from2007to2012and study itsinfluence on SST by analyzing kinds of data.The features of the cold airs affecting the Taiwan Strait (TS) were studied byanalyzing the buoy monitoring meteorological data in winter-half year from2007to2012, satellite remote sensing data and NCEP/NCAR Reanalysis data.It indicates that northeast or north wind affected TS most and the wind speed(daily average) concentrated at10~15m/s. Air temperature and SST continued toreduce from October to January next year, fluctuated in a certain range from Januaryto February, and started to rise after March. The residual current was mainlysouthwestward or southward in the west side of TS in winter, and the current speedconcentrated at10~30cm/s. The residual current speed in the middle of TS was themost fast, the current in the sea area near Ningde and in the north part of TS took thesecond place, and the current in the south part of TS was the slowest.During the process of cold air, the wind speed and the air temperature both havea clear4or8day fluctuation period, sea surface temperature and current have thesame fluctuation character, but relatively weak. The cold airs affecting Taiwan Straitin winter-half year from2007and2012were mainly weak intensity level. Higherfrequency and strongest cold airs affected the TS in December.The sea surface temperature (SST) in the northern part of the TS (around PingtanIsland) decreased most（1.0~2.0℃） in the cold airs influencing periods. The SST ofthe sea area near Ningde decreased less（about1.0℃） than the northern part of theTS, but more than the southern part of the TS（0.3~0.6℃）. The SST of the southern part of the TS decreased the least. There was a lag for SST to air temperature andresidual current’s change. The lag time was about1~2days and4~6days. The localair-sea interaction and the horizontal advection were important factors that made theSST of the Taiwan Strait decrease during the procedure of the cold airs. The localair-sea interaction was the major factor. The SST of TS decreased twice in a cold airprocedure because of the local air-sea interaction and the horizontal advection. Thefirst decrease which was major influenced by the local air-sea interaction happened2~3days after being affected and the second time which was major influenced by thehorizontal advection was4~6days after being affected by the cold airs.