The combination of a population of more than 1.2 billion people and the recent rapid industrialization and large-scale infrastructure projects have placed a very heavy burden on the coastal environment in China. Algal blooms and red tides pose a serious threat to public health, fisheries and aquaculture industry. Consequently, a thorough assessment of their impacts on the coastal zone is urgently needed. This research is the first application of the historical satellite remote sensing archive to investigate temporal and spatial patterns of pigment concentrations (PC) and sea surface temperatures (SST) on the entire continental shelf of China....[ Read more ]

The combination of a population of more than 1.2 billion people and the recent rapid industrialization and large-scale infrastructure projects have placed a very heavy burden on the coastal environment in China. Algal blooms and red tides pose a serious threat to public health, fisheries and aquaculture industry. Consequently, a thorough assessment of their impacts on the coastal zone is urgently needed. This research is the first application of the historical satellite remote sensing archive to investigate temporal and spatial patterns of pigment concentrations (PC) and sea surface temperatures (SST) on the entire continental shelf of China.

Firstly, I examined the temporal (annual/monthly) and spatial patterns of PC and SST on the continental shelf of China. The image availability for the study area was examined. A total of 2139 scenes were obtained from the study area during the years of the Nimbus-7 satellite mission (from 1978 to 1986), from which 76 monthly and 8 annual composite CZCS images were generated. AVHRR (Advanced Very High Resolution Radiometer) data from NOAA (National Oceanic & Atmospheric Administration) satellites were also examined. A distinctive high PC belt of about 50 km wide existed along the coastline of China, and a large plume of high PC was observed which extended nearly 500 km to the east from the Yangtze River. PC were high in the Yellow Sea (about 1-2 mg m^-3), it decreased seawards and southeastwards with a minimum value in the Philippine Sea (about 0.2 mg m^-3). Annual PC increased from 1979 and reached a peak in 1981; it dropped in 1982 with a strong El Nino. In the northern area (Yellow Sea), there were two peaks of PC in each year (spring and fall). In the southern area (northern South China Sea), PC was relatively low and constant over each year. A basin-wide gyre appeared in the center of the Yellow Sea in April 1986.

Secondly, I focused on the Luzon Strait, a channel between the Philippine Sea and the South China Sea. High concentrations (>1 mg m^-3) of pigment were detected 100 km southwest of the Strait during the winters of December 1979, February 1983, February 1985 and January 1986. Winter blooms (2-3 mg m^-3) persisted one to three weeks and extended over areas of about 100 x 200 km². The winter phytoplankton blooms appear to be related to upwelling in this area, which brings nutrients to the surface waters.

Finally, I examined the monthly variations of sea surface temperature (SST) in the northern South China Sea with NOAA satellite AVHRR data from May 1994 to April 1995. The result showed a very distinct temperature gradient along the coast of China from October to April, and a very distinct cold water belt along the coast in February and March. SST was lower in April and May, but it is much more uniform from June to August. During the year, the highest SST (30℃) existed in August and the lowest SST (14℃) appeared in February. Inshore SST varied closely with the season, while the offshore SST was relatively stable and uniform.