The Sources And Propagation Analysis Of Internal Waves In The South China Sea Based On Satellite Remote Sensing

Internal waves are often observed in the South China Sea. In this paper, theinternal wave sources and propagation in the South China Sea were investigated usingmore than3000Synthetic Aperture Radar (SAR) and optical satellite images from2005to2010.The internal wave crests and directions were extracted from these satelliteremote sensing images. The spatial distribution of internal waves shows that, internalwaves mainly occur in four regions of South China Sea:1) northeastern South ChinaSea,2) northwestern South China Sea,3) western South China Sea,4) southern SouthChina Sea. Most internal waves occur in the shelf of the northeastern South China Sea,northwestern South China Sea, western South China Sea and southern South ChinaSea. Internal waves are often observed in the northeastern South China Sea, but notobserved in the central and eastern South China Sea. Only in the deep sea from LuzonStrait to Dongsha Islands, internal waves can be observed by remote sensing. Thedistribution of observed internal waves is similar each year from2005to2010in theSouth China Sea. Internal waves can be observed all the year round, most in summer,least in winter. And internal waves can be seen all the month round, most in June andJuly, least in January. From the directions distribution, most internal waves propagateto the coast. Internal waves propagate northwestward or westward in northeastern andnorthwestern South China Sea, westward in western South China Sea, southwestwardin southern South China Sea.Based on the internal wave crests and directions, the propagation paths weredrawn with spatial statistical analysis. The results show that, in the northeastern SouthChina Sea, most internal waves propagate westward from the Luzon Strait and refractat Dongsha Island. Several internal waves impinge onto the shelf while few internalwaves reflect at Dongsha Island. Some internal waves propagate northeastward paralleling the isoth in the coast of Guangdong Province. A few internal wavespropagate offshore in the Pearl River Estuary. In the northwestern South China Sea,most internal waves propagate northwestward to the coast of Hainan Island orwestward into Beibu Gulf. Some internal waves propagate eastward from Beibu Gulf,and in south of Hainan Island some internal waves propagate southwestward to theVietnamese coast. In the western South China Sea, most internal waves propagatewestward to the Vietnamese coast, and few propagate southward to the deep sea. Inthe southern South China Sea, most internal waves propagate southwestward to thecoast. Some internal waves propagate southeastward to the coast of Kalimantan Island,and few internal waves propagate southeastward because of the influence of MekongRiver.Based on the internal wave crests and directions, the internal wave sources canbe found with the tide, current, depth and slope in the South China Sea. Internalwaves most generate by the interaction between tide or current and the bottomtopography, and the interaction between fresh water and seawater in the estuary. Thelargest internal wave source is Luzon Strait in the South China Sea, most internalwaves in the northeastern South China Sea generate here. In the shelf break ofnorthwestern, western and southern South China Sea, internal waves can generate bythe interaction between the tide or current and the topography. In the Pearl RiverEstuary, Red River Estuary and Mekong River Estuary, internal waves can generateand propagate offshore. Internal waves also can generate at the water channels of theXisha Islands.