Underwater optical environment in the Upper Gulf of Thailand

Because the composition of coastal water is full of variety by each region, relationship between chlorophyll-a (chl.a) concentration as a indicator of primary productivity derived by satellite ocean color data and in situ data of chl.a may not be same always. Those relations or algorithms should be verified at each coastal water for managing coastal environment. Coastal ocean color algorithms should be built up at each coastal water or at least should be verified by wide range field data for practical application at each region. Intensive research cruises were conducted at the Upper Gulf of Thailand. Optical survey using PRR (Profiling Reflectance Radiometer) showed the character of the Upper Gulf water. Under water optical algorithms for that water were suggested by these survey data. Optical depths in the Gulf of Thailand were also measured to know the compensation depth for primary production. Although the transparency measured by Secchi disk is not so large and surface water looks very turbid, the light energies are reaching to near bottom at almost all stations of the upper Gulf. It suggests that the turbidity of this water were mainly composed of scattering material like as clay mineral rather than absorbing material like as phytoplankton pigment or CDOM