CalCOFI collects samples for inorganic carbon and total alkalinity at specific stations throughout the cruise track. Seawater samples are collected from several depths, preserved and brought back to SIO for total inorganic carbon and total alkalinity analysis. These measurements allow the calculation of pH and pCO2. The objectives of these measurements are: first, the long-term characterization of the inorganic carbon system and its response to changing ocean climate, and second, measurements of pH in the coastal zone in order to monitor the anthropogenic impact on coastal ecosystems in the Southern California Bight.

DIC samples for Dave Keeling were also collected on CalCOFI stations 90.70, 90.90, & 90.120 from Sep 1986 (CalCOFI 8609NH) to Nov 2002 (CalCOFI 0211NH). In Aug 2008, DIC sampling restarted on 7 stations, grew to 10 stations in Jan 2011, and currently DIC has expanded substantially (see figure & table). Dissolved inorganic carbon (DIC) and total alkalinity (TA) data have only been integrated into the CalCOFI hydrographic dataset since Aug 2008, then Jan 2009 through presently. Similarly, pH data have only been integrated into the CalCOFI hydrographic dataset since April 2014.

Link to Dissolved Inorganic Carbon & Total Alkalinity Data CSV's (200808, 200901 - 201507) extracted from the CalCOFI Hydrographic MS Access Database.