Preprints
https://doi.org/10.5194/egusphere-2022-710
https://doi.org/10.5194/egusphere-2022-710
 
04 Aug 2022
04 Aug 2022
Status: this preprint is open for discussion.

High interannual surface pCO2 variability in the Southern Canadian Arctic Archipelago's Kitikmeot Sea

Richard Peter Sims1,a, Mohamed Ahmed1,2, Brian J. Butterworth3,4, Patrick J. Duke5, Stephen F. Gonski6, Samantha F. Jones1, Kristina A. Brown7, Christopher J. Mundy8, William J. Williams7, and Brent G. T. Else1 Richard Peter Sims et al.
  • 1Department of Geography, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
  • 2Geology Department, Beni-Suef University, 101 Salah Salem St., Bani Sweif, 62511, Egypt
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 4NOAA Physical Sciences Laboratory, Boulder, Colorado, USA
  • 5School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
  • 6School of Marine Science and Policy, University of Delaware, Lewes, Delaware, USA
  • 7Fisheries and Oceans Canada, Sidney, British Columbia, Canada
  • 8Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
  • anow at: Centre for Geography and Environmental Science, College of Life and Environmental Sciences, University of Exeter, Penryn campus, United Kingdom

Abstract. Warming of the Arctic due to climate change means the Arctic Ocean is now ice-free for longer as sea ice melts earlier and refreezes later. It remains unclear how the extended ice-free period will impact carbon dioxide (CO2) fluxes due to scarcity of surface ocean CO2 measurements. Baseline measurements are urgently needed to understand how air−sea CO2 fluxes will spatially and temporally vary in a changing Arctic Ocean. It is uncertain whether the previous basin-wide surveys are representative of the many smaller bays and inlets that make up the Canadian Arctic Archipelago. By using a research vessel that is based in the remote Inuit community of Cambridge Bay (Ikaluqtuutiak, Nunavut), we have been able to reliably survey pCO2 shortly after ice melt and access previously unsampled bays and inlets in the nearby region. We present four years of consecutive summertime pCO2 measurements collected in the Kitikmeot Sea in the southern Canadian Arctic Archipelago. Overall, we found that this region is a sink for atmospheric CO2 in August (average of all calculated fluxes over the four cruises was -8.3 mmol m-2 d-1) but the magnitude of this sink varies substantially between years and locations (average calculated fluxes of 0.41, -7.70, -21.26 and -2.08 mmol m-2 d-1 during the 2016, 2017, 2018 and 2019 cruises respectively). Surface ocean pCO2 varied by up to 142 μatm between years; this highlights the importance of repeat observations in the Arctic as this high interannual variability would not have been captured by sparse and infrequent measurements. We find that the pCO2 value of the surface ocean at the time of ice melt is extremely important in constraining the magnitude of the air−sea flux throughout the ice-free season. Further constraining the flux in the Kitikmeot Sea will require a better understanding of how pCO2 changes outside of the summer season. Surface ocean pCO2 measurements made in the bays and inlets in the Kitikmeot Sea were ~20–40 μatm lower than in the main channels, and pCO2 measurements made close to ice breakup (i.e. within 2 weeks) were 50–100 μatm lower than measurements made >4 weeks after breakup. As basin-wide surveys of the CAA have focused on the deeper shipping channels and rarely measure close to the ice break-up date, we hypothesize that there may be an observational bias in previous studies, leading to an underestimate of the CO2 sink in the Canadian Arctic Archipelago. These high-resolution measurements constitute an important new baseline for gaining a better understanding of the role this region plays in the uptake of atmospheric CO2.

Richard Peter Sims et al.

Status: open (until 29 Sep 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Richard Peter Sims et al.

Richard Peter Sims et al.

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Short summary
Using a small research vessel based out of Cambridge Bay in the Kitikmeot Sea (Canadian Arctic Archipelago), we were able to make measurements of surface ocean pCO2 shortly after sea ice breakup for four consecutive years. We compare our measurements to previous underway measurements and the two ongoing ocean carbon observatories in the region. We identify high inter annual variability and a potential bias in previous estimates due to lower pCO2 in bays and inlets.