Variations of ƒCO2 and air‐sea flux of CO2 in the Greenland Sea gyre using high‐frequency time series data from CARIOCA drift buoys

Abstract

A 6 month, high‐frequency (hourly) time series of ƒCO2 and sea surface temperature measured by CARIOCA drift buoys in the Greenland Sea gyre is presented. The ƒCO2 shows the effects of photosynthetic activity in the summer, with ƒCO2 values as low as 260 μatm, followed by an increase to approximately 310 μatm in the late fall and winter due to mixing with CO2‐rich deep water from below, remineralization, and gas exchange. The time series shows that ƒCO2 in the Greenland Sea gyre is undersaturated with respect to the atmosphere year‐round, having an average ΔƒCO2 of −71 μatm. Linear correlations between the measured ƒCO2 normalized to a constant temperature of −1°C and sea surface temperature (SST) are used to construct high‐resolution ƒCO2 and air‐sea CO2 flux maps for the Greenland Sea gyre area using SST and wind speed data from the European Centre for Medium‐Range Weather Forecasting and ice information from the Special Sensor Microwave / Imager on a 0.5° × 0.5° grid. The CO2 flux for the Greenland Sea gyre calculated for 1996–1997 considering the effects of blockage of gas exchange by sea ice is estimated to be −2.4 to −4.2 × 1012 g C yr−1 depending on the gas exchange parameterization used.