Variables Salient features of the GoM
Surface currents Water flow in the GoM is in conjunction with the large scale circulation between the Arabian Sea and the Bay of Bengal 8-10. An eastward flow along the Indian shelf during the SWM carrying upwelled and plankton-rich waters from the Indian southwestern shelf. A westward current during the NEM carrying relatively low saline and plankton-rich waters from the inshore of the Bay of Bengal.
Wind, Sea surface temperature, Sea surface salinity Strong winds prevail in the GoM during the SWM, followed by the NEM 8-10. Surface waters are cold during the SWM due to the advected water from the western Indian shelf. The low-saline and cold Bay of Bengal waters occupy the surface waters along the Indian shelf during the NEM.
Waves The waves are lower in the GoM as compared to the SEAS9. Swells dominate during SWM and wind seas during the rest.
Turbidity Clear waters occur in the GoM throughout the year, while Palk Bay acts as a sediment trap during the NEM preventing intrusion of the high suspended sediment into the GoM10-12.
Nitrate and Dissolved oxygen Moderate to the high concentration of nitrate during SWM and NEM11-12 Dissolved oxygen is high throughout the year, and the entire water column has always > 5 mg/l.
Chlorophyll a Moderate (0.4 mg m3) to high (1.8 mg m3) level of phytoplankton stock (chlorophyll-a) exists in the GoM throughout the year 8,10-12. A higher concentration of chlorophyll-a is evident in the GoM during SWM and NEM.
Zooplankton GoM has high zooplankton stock during the SWM and NEM periods 8,11. Upwelling indicator copepods Timora turbinata occur in high abundance during the SWM associated with the upwelled waters from the Indian southwestern shelf. Similarly, Paracalanus purvus, an abundant copepod in the low saline waters of the BoB occur abundantly during the NEM indicating Bay of Bengal water intrusion during the period