Three-dimensional Simulation of Seasonal variations of the Biogeochemical Parameters in the Persian Gulf using an NPZD Model

In this study, to investigate the seasonal changes in some biological parameters of the Persian Gulf, a coupled physical-biological ROMS model is used. The biological model coupled with the physical model has seven state variables includes two nutrients, phytoplankton, chlorophyll, zooplankton and small and large detritus (N2PChlZD2). The results show that the pattern of seasonal changes in chlorophyll-a in the Persian Gulf can be divided into two regions. The first region is the northwestern part, where the growth of chlorophyll begins in spring and extends eastwards along the southern coasts until late summer and early autumn. The amount of chlorophyll-a in this region throughout the year is higher than the other parts of the Gulf and also peaks in early spring. The second region, which includes the middle and east parts of the Persian Gulf blooms in summer and peaks from late summer until early autumn. Moreover the results also show that the pattern of growth and expansion of chlorophyll-a in the Persian Gulf are independent of the Sea of Oman pattern, and its changes follow the pattern of Persian Gulf currents. In addition, the results show that there is a high concentration of nitrate in the northwest of the Persian Gulf, that it is a good reason for beginning of the phytoplankton blooms from the northwestern part of the Persian Gulf and its extension to the other parts along with the regional currents.