Analysis of the effects on sea surface temperature and ocean color environment by typhoon Haitang(2005) based on remote sensing in Taiwan Strait

摘要

A typhoon (as well as a hurricane or tropical storm) is one of the largest air-sea interaction processes on the synopticscale, which can greatly enhance the air-sea exchange of material and energy within a short time; meanwhile, a typhooncan significantly alter the water structure, seabed topography and geomorphology, and particle transport and deposition,as well as biogeochemical processes in the affected areas. Satellite remote sensing is the main approach to study theimpact of typhoon on the sea surface temperature(SST) and the ocean color environment at present. The Taiwan Straitplays an important role in water and sediment exchange between the East China Sea and the South China Sea. This paperuses the data of the MODIS satellites to analyses the effects of Haitang(2005) on the SST, sea surface chlorophyll-aconcentration(Chl-a) and total suspended matter(TSM) in the Taiwan Strait over different periods. During thetyphoon-active period, the concentration of TSM significantly increased. The SST for the typhoon-active period waslower than that both the pre- and post- the typhoon periods. During the typhoon, Chl-a concentration increased. After thetyphoon, the Chl-a concentration decreased, but still higher than before the typhoon. The Chl-a concentration near theMinjiang Estuary during the typhoon was slightly lower than that before the typhoon and after the typhoon. During thetyphoon, the strong cyclonic wind-stress of the typhoon enhanced heat exchange between the water and the atmosphere,and a large amount of rainfall and run-off significantly decreased the SST. During the typhoon, the increased sedimentdischarged into the strait by rivers, and the re-suspension of seafloor sediment, increased the concentration of TSM in thecoastal waters. Seawater with relatively high sediment concentration was transported to the middle of the strait afterbeing carried by wind-induced flows. During the typhoon, in the waters near the typhoon’s path, Chl-a concentrationincreased. After the typhoon, Chl-a concentration near the Minjiang estuary dramatically increased than before thetyphoon. Nutrient-rich bottom water stirred by the typhoon promoted an outbreak of aquatic organisms. The increase ofChl-a concentration has a certain delay because the growth of organisms takes time.