Inter-comparison between chambers for CO2 flux measurements over sea ice

In order to validate the difference of air-sea ice CO2 flux measurements by different types of CO2 chamber, inter-comparison experiments were carried out on winter Antarctic pack ice in the Weddell Sea (R.V. Polarstern AWECS cruise, July-August 2013). Our ultimate goal is to understand the methodological gaps for the CO2 flux measurements betweem chamber and eddy covariance methods over sea ice as an activity for SCOR Working
Group 152 (ECV-Ice). Two kinds of CO2 chamber systems were used: semi-automated CO2 chambers developed
at Hokkaido University and automated long-term CO2 chambers (Li-8100A, LI-COR Biosciences, USA). These chambers were installed at the same ice/snow surface conditions within a 2-m × 2-m area. Based on the quantitative comparisons using least squares linear regression analyses, slope was 1.08, suggesting that the airsea ice CO2 flux from two chambers were good agreement. Therefore, our inter-comparison experiments confirmed that there was no instrumental bias between two chambers, thereby the past data for air-sea ice CO2 flux obtained by each chamber's group in the world polar oceans could be shared.