Seasonal Variability Analysis of Sea Water pCO2 Over North Western Indian Ocean

The gradient of the partial pressures of CO₂ in the air and water interface is the primary factor in determining the direction of CO₂ flux. The spatial and seasonal fluctuations are very large in the sea water CO₂ partial pressure as compared to the atmospheric pCO₂. The global range of sea water pCO₂ is around 150- 550 μatm which around 60% below and above the atmospheric pCO₂. The CO₂ partial pressures in sea water are primarily regulated by the temperature changes and variations in the CO₂ concentrations in water due to the biological activities. The sea water CO₂ partial pressures were derived using MODIS sea surface temperature and chlorophyll data. The variations in the partial pressures were analysed for winter, pre-monsoon, monsoon and post monsoon seasons. The partial pressure values showed an increasing gradient from winter through pre-monsoon and monsoon towards post monsoon season. The intrusion of low saline waters in winter from the eastern Indian Ocean might have caused the lowering of partial pressure values while the coastal upwelling during monsoon season can be a reason for the gradual increase of sea water partial pressures.