| Summary: | The Ross Sea is an important region in the global carbon cycle, however little is known about the effects of surface mesoscale processes (on spatial scale of 10 km and temporal ranges from hours to days) on the carbonate system chemistry and CO2 air–sea fluxes. To this purpose, the Ross Sea Mesoscale Experiment (RoME) project during the austral summer 2013-14 used a combination of remote sensing and high resolution ship measurements to investigate the importance of mesoscale circulation in the distribution of the biogeochemical properties of the surface waters in the shelf area. Sampling was performed in selected areas, characterized by different distances from the coast and different hydrodynamic structures. RoME 1 area was located at approximately 170E and 75S, whereas RoME 3 in the southwestern Ross Sea, NE of Ross Island, at 168E and 76.5S. Total alkalinity, pH, O2, nutrients, phytoplankton pigments and composition were investigated in combination with measurements of temperature, salinity and current speed. Total inorganic carbon, sea water CO2 partial pressure and the saturation state (Ω) for calcite and aragonite were calculated from the measured parameters. In addition, continuous measurements of atmospheric CO2 concentration were completed. Our results document substantial spatial heterogeneity and complexity in carbonate system properties and the magnitude of the CO2 flux at a horizontal length scale of about 10 km, emphasizing the importance of mesoscale events to regional biogeochemistry. The distribution of the carbonate system was controlled primarily by phytoplankton activity rather than physical forcing, which, on the other hand, created the favorable conditions for the growth in the upper layer of the water column.
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