Exploiting MODIS data for estimating sea surface nitrate from space



A better understanding of the oceans' carbon cycle and a reduction in existing uncertainties in estimates of CO2 fluxes between the atmosphere and the oceans have become central to several contemporary programs. Oceanic CO2 fluxes are largely regulated by the “solubility pump” and the "biological pump." The solubility pump is governed by physical processes that include near-surface conditions at the air-sea interface, the partial pressure of CO2 between the sea surface and the atmosphere, and the solubility of CO2 in seawater.

The biological pump, in turn, is regulated by phytoplankton photosynthesis, which converts CO2 to organic matter. The fraction of newly photosynthesized carbon exported to depth in the oceans is referred to as “export production” or “new production,” and is largely dependent on exogenous nitrogeneous nutrient inputs, primarily nitrate into the euphotic zone [Eppley and Peterson, 1979].