Internal waves can bring nutrients to the upper level of water bodies and facilitate phytoplankton photosynthesis.Internal waves occur frequently in the northern portion of the South China Sea and inflict an important effect on chlorophyll a distribution.In this study,in-situ observation and satellite remote sensing data were used to study the effects of internal waves on chlorophyll a distribution.Based on the in-situ observations,lower chlorophyll a concentrations were present in the middle and bottom level in areas in which internal waves occur frequently,while the surface chlorophyll a distribution increased irregularly,and a small area with relatively higher chlorophyll a concentrations was observed in the area around the Dongsha Island.Satellite remote sensing showed that the chlorophyll a concentration increased in the area near Dongsha Island,where internal waves frequently occurred.The results of the increased chlorophyll a concentration in the surface water near Dongsha Island in the northern portion of the South China Sea indicated that internal waves could uplift phytoplankton and facilitate phytoplankton growth.
Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.
