3:30 PM - 5:00 PM
[AOS13-P03] Simulation of phytoplankton dynamic in the Gulf of Thailand: a case study of the physical-biogeochemical model
Keywords:Chlorophyll-a, Phytoplankton, Gulf of Thailand, Physical-biogeochemical model
The dynamics of the marine ecosystem in the Gulf of Thailand were investigated using a 3-dimensional physical model, the Princeton Ocean Model (POM), coupled with a Nutrients-Phytoplankton-Zooplankton-Detritus (NPZD) model. The monthly climatological data of wind, net heat flux, river discharge, and nutrient climatological fields from the World Ocean Atlas 2018 were used as major forcing parameters. The simulated both spatial and temporal variations of the surface chlorophyll-a (chl-a) was compared with MODIS chl-a data. The simulated chl-a shows a similar pattern with satellite data. During the northeast and southwest monsoons (winter and rainy seasons), chl-a is generally high throughout the area, especially in the upper Gulf of Thailand and near Ca Mau Cape, Vietnam. Chl-a decreases during non-monsoon (summer season), especially in the offshore area. The Empirical Orthogonal Function (EOF) analysis emphasizes the different variations of chl-a between the coastal and offshore areas by explaining 42% of the total variance in the first mode. The EOF result suggests that different mechanisms may contribute to phytoplankton variation in the coastal and offshore areas. In offshore area, phytoplankton may respond to water column conditions. Water stratification/mixing is created by strong/low surface heating and weak/strong wind during summer/winter resulting in low/high chl-a concentrations. Net heat flux and wind are important factors that control phytoplankton variation in offshore area. Meanwhile, chl-a in the coastal area may relate to nutrient loading and ocean circulation that transport nutrients from the river to the surrounding area. Further investigation of phytoplankton-physical process interaction will be conducted.