Articles | Volume 15, issue 11
Biogeosciences, 15, 3331–3343, 2018
Biogeosciences, 15, 3331–3343, 2018

Research article 05 Jun 2018

Research article | 05 Jun 2018

CO2 flux over young and snow-covered Arctic pack ice in winter and spring

Daiki Nomura1,2,3,4, Mats A. Granskog5, Agneta Fransson5, Melissa Chierici6,7, Anna Silyakova8, Kay I. Ohshima1,3, Lana Cohen5, Bruno Delille9, Stephen R. Hudson5, and Gerhard S. Dieckmann10 Daiki Nomura et al.
  • 1Institute of Low Temperature Science, Hokkaido University, Kita 19, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0819, Japan
  • 2Faculty of Fisheries Sciences, Hokkaido University, 3-1-1, Minato-cho, Hakodate, Hokkaido 041-8611, Japan
  • 3Arctic Research Center, Hokkaido University, Kita 21, Nishi 11, Kita-ku, Sapporo, Hokkaido 001-0021, Japan
  • 4Global Station for Arctic Research, Global Institution for Collaborative Research and Education, Hokkaido University, Kita 8, Nishi 5, Kita-ku, Sapporo, Hokkaido 060-0808, Japan
  • 5Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway
  • 6Institute of Marine Research, 9294, Tromsø, Norway
  • 7FRAM-High North Research Centre for Climate and the Environment, Tromsø, Norway
  • 8CAGE, Centre for Arctic Gas Hydrate, Environment and Climate, Tromsø, Norway
  • 9Unité d'Océanographie Chimique, Freshwater and Oceanic Science Unit of Research (FOCUS), Université de Liège, Liège, Belgium
  • 10Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

Abstract. Rare CO2 flux measurements from Arctic pack ice show that two types of ice contribute to the release of CO2 from the ice to the atmosphere during winter and spring: young, thin ice with a thin layer of snow and older (several weeks), thicker ice with thick snow cover. Young, thin sea ice is characterized by high salinity and high porosity, and snow-covered thick ice remains relatively warm ( >  −7.5 °C) due to the insulating snow cover despite air temperatures as low as −40 °C. Therefore, brine volume fractions of these two ice types are high enough to provide favorable conditions for gas exchange between sea ice and the atmosphere even in mid-winter. Although the potential CO2 flux from sea ice decreased due to the presence of the snow, the snow surface is still a CO2 source to the atmosphere for low snow density and thin snow conditions. We found that young sea ice that is formed in leads without snow cover produces CO2 fluxes an order of magnitude higher than those in snow-covered older ice (+1.0 ± 0.6 mmol C m−2 day−1 for young ice and +0.2 ± 0.2 mmol C m−2 day−1 for older ice).

Final-revised paper