Inorganic carbon fluxes through the boundaries of the Greenland Sea Basin based on in situ observations and water transport estimates

A carbon budget for the exchange of total dissolved inorganic carbon C-T be tween the Greenland Sea and the surrounding seas has been constructed for w inter and summer situations. An extensive data set of C-T collected over th e years 1994-1997 within the European Sub-polar Ocean Programmes (ESOP1 and ESOP2) are used for the budget calculation. Based on these data, mean valu es of C-T in eight different boxes representing the inflow and outflow of w ater through the boundaries of the Greenland Sea Basin are estimated. The o btained values are then combined with simulated water transports taken from the ESOP2 version of the Miami Isopycnic Coordinate Ocean Model (MICOM). T he fluxes of inorganic carbon are presented for three layers; a surface mix ed layer, an intermediate layer and a deep layer, and the imbalance in the fluxes are attributed to air-sea exchange, biological fixation of inorganic carbon, and sedimentation. The main influx of carbon is found in the surfa ce and the deep layers in the Fram Strait, and in the surface waters of dir ect Atlantic origin, whereas the main outflux is found in the surface layer over the Jan Mayen Fracture Zone and the Knipovich Ridge, transporting car bon into the Atlantic Ocean via the Denmark Strait and towards the Arctic O cean via the Norwegian Sea, respectively. The flux calculation indicates th at there is a net transport of carbon out of the Greenland Sea during winte rtime. In the absence of biological activity, this imbalance is attributed to air sea exchange, and requires an oceanic uptake of CO2 of 0.024 +/- 0.0 06 Ct C yr(-1). The flux calculations from the summer period are complicate d by biological fixation of inorganic carbon, and show that data on organic carbon is required in order to estimate the air-sea exchange in the area. (C) 1999 Elsevier Science B.V. All rights reserved.