Sea surface salinity of ocean waters has been obtained from L-band microwave radiometer on satellite, such SMOS,Aquarius and SMAP. It provides a new technology and way to observe the salinity over large region from space.However, it is still difficult to get the sea surface salinity of the coastal waters due to that the effect on satellite-observedmicrowave radiance of radio frequency interference over near-shore regions. Fortunately, the colored dissolved organicmatter (CDOM) has conservative or semi-conservative property in the freshwater areas of coastal rivers and it has a goodlinear correlation between the absorption coefficient of CDOM and salinity. Based on those, a conservative mixingrelationship between the fresh water from the Pearl River and the sea water from the South China Sea are established andthe distribution of sea surface salinity from MODIS-retrieved absorption coefficient of CDOM (aCDOM) at 355nmwavelength in this study. The linear relationship between salinity and aCDOM at 355 nm under conservative mixingconditions can be established from the in-situ observed salinity and MODIS-retrieved aCDOM at 355 nm at the centralwater mass in the Pearl River Estuary and the northern basin region of South China Sea. By comparing daily observedMODIS-retrieved sea surface salinity with the in-site observed salinity, it shows that the salinity retrieved from satellitebasedaCDOM has good agreement with observations, and it can better capture the location of low salinity fresh water inthe Pearl River. For the summer averaged satellite-based salinity from 2002 to 2018, sea surface salinity are graduallyincreases from the vertical coastline to the sea in the Pearl River Estuary region. The salinity in coastal region is low bythe effect of the Pearl River diluted water, and the salinity in offshore region is high. On average, the distribution ofsalinity shows that the diffusion of fresh water from the Pearl River generally spread along the coastline to the east andwest in summer, while the runoff on the westward is larger and on the eastward it is affected by some flushing water ofother rivers. In the future, MODIS-retrieved salinity can be as a supplement to salinity inversion of Microwaveradiometer in the coastal region.
展开▼
