The Arctic region is considered to be vulnerable to the global warming, which would potentially enhance emissions of the greenhouse gases (GHGs) including CO2 and CH4 from the carbon pools in the Arctic regions into the atmosphere. In order to detect the increases in the emissions of GHGs associated with the ongoing global warming in the Arctic region in the early stage, continuous observations of the atmospheric CO2 and CH4 mixing ratios during this MR17-05C cruise. Atmospheric CO2, CH4, and CO mixing ratios were measured by a wavelength-scanned cavity ring-down spectrometer (WS-CRDS, Picarro, G2401). The air sample, drawn from an air intake placed on the right-side of the upper deck, was introduced into the WS-CRDS. The WS-CRDS was automatically calibrated every 25 hour by introducing 3 standard airs with known CO2, CH4 and CO mixing ratios and the analytical precisions for CO2, CH4, and CO mixing ratios were about 0.02 ppm, 0.3 ppb and 3 ppb, respectively. The shipboard measurements were conducted during the entire cruse (23 August – 2 October, 2017).

Atmospheric CO2, CH4, and CO mixing ratios (R/V Mirai Cruise MR17-05C)