Estimation of ocean export production ratios based on mixed layer depth and satellite chlorophyll observations

Abstract

We introduced a simple methodology to determine basin-wide marine export production ratios during spring phytoplankton bloom periods by combining monthly varying mixed layer depths (MLD) derived from observed temperature depth profiles, satellite time series of chlorophyll-a (Chl-a) concentrations, and hypothetical critical depth. The MLD-Chl-a based approach yielded monthly export ratios reflecting seasonal variability of net community production in correlation with the MLD variations. Regional averages of export ratio in the spring for the southern part of the East Sea (36–39°N, 130–134°E), North Pacific Ocean (42–45°N, 151–155°E), and North Atlantic Ocean (57–60°N, 17–21°W) are 0.44 ± 0.22, 0.42 ± 0.16, and 0.73 ± 0.29, respectively, which compare favorably with prior field data. This suggests that the approach enables estimation of export production ratios with high spatial and temporal resolutions, complementing the methods that rely on extrapolation of limited field measurements to larger space and time scales.