Satellite-derived estimates of primary production during the Sargasso Sea winter/spring bloom: Integration of in-situ time-series data and ocean color remote sensing observations

Accurate estimates of primary production from satellite-derived data on both regional and global scales are one of the most important goals of international ocean color remote-sensing programs. This manuscript presents surface concentrations and vertical distributions of chlorophyll-a (Chl-a) data as a proxy for phytoplankton biomass, and calculated photosynthesis-irradiance (P-E) curve parameters, which were used to estimate integrated monthly primary production in the Sargasso Sea euphotic zone from 2004 to 2009. The measured surface Chl-a in the Sargasso Sea was low but exhibited strong seasonal variation, and correlated well with satellite estimates of Chl-a. Underwater light transmission was modeled using a shifted Gaussian model from 69 vertical Chl-a profiles, which were collected in the Sargasso Sea. The P-E curve parameters were experimentally derived; the maximum photosynthetic rate, PmB ranged from 1.51 to 3.05 (mgC(mgChl-a)−1h−1) and the maximum light utilization coefficient, αB, ranged from 0.017 to 0.806 (mgC(mgChl−a)−1(Wm−2)−1 h−1). These data and previously published P-E curve parameter estimates were used in a spectrally varying model to estimate integrated primary production in the Sargasso Sea euphotic zone. Output from two of the four primary production models agreed well with in-situ measurements (±20%) and captured the strong seasonal variation.