The underway fCO2 data files consist of 15 columns of data:

JUL_DATE         = Julian decimal day
DATE             = month/day/year
TIME             = 01:00:00 to 23:59:59
LAT              = Latitude (negative numbers for the southern hemisphere)
LON              = Longitude (negative numbers for the western hemisphere)
XCO2_WAT         = mole fraction of carbon dioxide in water (ppm)
XCO2_AIR         = mole fraction of carbon dioxide in air (ppm)
EQ_TMP           = temperature recorded inside the equilibrator
ATM_PRE          = atmospheric pressure (mB)
SST              = sea surface temperature (DEG_C) at the bow intake
SSS              = sea surface salinity at the bow intake
FCO2_EQ          = fugacity of CO2 in the equilibrator (UATM)
FCO2_WAT         = fugacity of CO2 in surface seawater (UATM)
FCO2_AIR         = fugacity of CO2 in air (UATM)
DEL_FCO2         = f(CO2)w, in situ minus f(CO2)a (UATM)