Ocean Surface Carbon Dioxide Fugacity Observed from Space

The ocean as the source and sink of carbon dioxide is important to global warming, ocean biogeochemistry, and ecology, but its quantitative variation is insufficiently known. The exchange depends on the difference in fugacity (partial pressure) of carbon dioxide between sea and air, and a transfer velocity. The transfer velocity has traditionally been parameterized in terms of wind speed, which has been measured by a number of spacebased sensors. The fugacity in air is believed to change much less than fugacity in sea. Fugacity in sea is measured largely on ships; they are not sufficient to characterize spatial and temporal variability. Attempts have been made in the past to relate the fugacity in sea to parameters (drivers) that could be measured from space. These relations are found to be valid only in limited regions and in specific seasons. We have developed a statistical model to estimate the fugacity over global ocean for all seasons from NASA space measurements using the state-of-art statistical techniques. The input data are spaced-based observations of sea surface temperature, and chlorophyll with climatological surface salinity. Nine years of surface fugacity has been produced and validated. The role of these drivers in various regions and seasons are examined. The newly released surface salinity data from Aquarius are used to examined sensitivity of the fugacity on salinity changes.