Seasonal Distribution And Mechanism Of Turbidity In Beibu Gulf And Taiwan Strait By MODIS

Study on the turbidity of water has been considerd as an important part of ocean color remote sensing. In this thesis, Beibu Gulf and Taiwan Strait were chosen as study regions to understand seasonal distributions and mechanisms of turbidity by one year MODIS images and related sea in-situ data.This thesis described the seasonal distributions of turbidity in Beibu Gulf. The results suggested that the distributions of turbidity were generally similar with chlorophyll: higher in coastal than in offshore regions and higher in winter than in summer. The ratio of chlorophyll and turbidity (K) was introduced and it revealled that the high turbidity coastal water was dominanted by river output and re-suspended sediments, whereas planktons affected slightly. Dramaticly change of K from coastal to offshore revealled that plankton was one of the dominating compositions of suspended particle matter in the open area. Two main transporting routes of particle matter aross the Gulf were identified in summer and winter individually. Around them a route appeared as a high turbidity band emerged on the northwest of Beibu Gulf during December and January, on account of tidal mixing front related circulations.This thesis also described seasonal variable features of turbidity in each sub-region of Taiwan Strait. High turbidity regions existed in the estuarial plumes, longshore currents, shallows and the water around islands. Turbidity of longshore current was highest in the winter-half-year. With the estuarial plumes, turbidity went to its peak of the year in summer. The seasonal features of K also revealed eastward transportting routes of particles across the strait both in autumn and winter. A tongue-like low K district effectted by terrestrial material was observed in October on the southeast of the strait, which crossed the Peng-hu Submarine Canyon from northeast to southwest and extendeded 100～200km along the continental slope of the southern Strait. Possiblly it's considered to be the turbid layer diffused horizontally along the pycnocline from the shelf marginal to the deep sea.