Interannual variability of fCO2 in the Greenland and Norwegian Seas

Abstract

The fCO2 in the Greenland and Norwegian Seas surface water varied significantly during the period from 1995 to 1997. Comparison of fCO2 data from winter 1995 with data from winter 1997 showed that sea surface fCO2 decreased between these winters by 20 to 30 μatm in the central Greenland Sea, and the potential CO2 uptake during the winters of 1995 and 1997 was 3.9 · 10-3 Gt C month-1 and 5.9 · 10-3 Gt C month-1 (based on Wanninkhof's relationship for the gas transfer coefficient), respectively. This difference in CO2 fluxes can be attributed to lower sea surface temperatures and more extensive sea ice cover in 1997, and these observations were related to increased convection in the Greenland Sea during winter 1997. Larger amplitudes in the seasonal variations of CO2 flux were also seen during the other seasons in the period 1996-97, compared to 1995. Over the years of investigation in the Greenland Sea, the carbon flux showed an increasing trend of 9 · 10-4 Gt C yr-1 into the ocean, which may be related to the anthropogenic input of carbon to the atmosphere. The Greenland and Norwegian Seas appear to be sinks for atmospheric CO2 and together absorb approximately 0.12±0.015 Gt C yr-1.