Mole fraction of carbon dioxide (xCO2) in water and atmosphere, temperature, salinity and other parameters collected from surface underway observations during the R/V Isabu cruise ES1801 (EXPOCODE 24KX20180126) in the Japan Sea from 2018-01-26 to 2018-02-01 (NCEI Accession 0177984)

This dataset consists of the surface underway measurements of mole fraction of carbon dioxide (xCO2) in water, xCO2 in outside air associated with each water analysis, sea surface temperature, sea surface salinity and barometric pressure during the R/V Isabu cruise ES1801 (EXPOCODE 24KX20180126) in the Japan Sea from 2018-01-26 to 2018-02-01. This data were collected using General Oceanics Model 8050 with Li-Cor 7000. The underway system was operated on a cycle of 3 standard gases, 10 measurements of air, and 100 measurements of a headspace equilibrated with flowing seawater. The system measured the xCO2 in dry air, which was converted into fugacity of carbon dioxide (fCO2) by correcting for the non-ideality of the gas and the water vapor level, as outlined by Pierrot et al. (2009).