Carbon dioxide flux in the Java Sea estimated from satellite measurements

Abstract

The oceans play a pivotal role in the carbon cycle due to its dynamics to act as a carbon source or sink to the atmosphere. Previous studies showed that the Java Sea acts as a carbon dioxide (CO2) source. However, their analysis was only based on the observation data which was limited in time and coverage. In the present study, we utilize the advantage of satellite measurements which have wide coverage and continues monitoring. Sea surface temperature, chlorophyll-a, sea surface salinity, surface wind speed, tropospheric mole fraction of CO2 and sea level pressure were analyzed to calculate CO2 gas transfer velocity, CO2 solubility, CO2 pressure in the sea water and atmosphere to estimate CO2 flux in the Java Sea. We found that the Java Sea acts as a CO2 source. However, during May 2015 and August 2016 small areas along the southern Borneo Island become the sink areas of CO2. The influence of CO2 gas transfer velocity and CO2 solubility is stronger than the difference of CO2 pressure between sea and atmosphere to determine CO2 flux in the Java Sea. Therefore, wind speed and sea surface salinity play important role to determine the variability of CO2 flux in the Java Sea. El Niño condition tends to amplify the release of CO2 to the atmosphere since CO2 gas transfer velocity, CO2 solubility and the difference of CO2 pressure between sea and atmosphere increases during El Niño.