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Climatological Distributions of pH, pCO2, Total CO2, Alkalinity, and CaCO3 Saturation in the Global Surface Ocean (NCEI Accession 0164568)

Published by NOAA National Centers for Environmental Information | National Oceanic and Atmospheric Administration, Department of Commerce | Metadata Last Checked: January 29, 2026 | Last Modified: 2017-08-04T00:00:00.000+00:00
Climatological mean monthly distributions of pH in the total H+ scale, total CO2 concentration (TCO2), and the degree of CaCO3 saturation for the global surface ocean waters (excluding coastal areas) are calculated using a data set for pCO2, alkalinity and nutrient concentrations in surface waters (depths less than 50 m), which is built upon the GLODAP, CARINA and LDEO database. The mutual consistency among these measured parameters is demonstrated using the inorganic carbon chemistry model with the dissociation constants for carbonic acid by Lueker et al. (2000) and for boric acid by Dickson (1990). The global ocean is divided into 24 regions, and the linear potential alkalinity (total alkalinity + nitrate) versus salinity relationships are established for each region. The mean monthly distributions of pH and carbon chemistry parameters for the reference year 2005 are computed using the climatological mean monthly pCO2 data adjusted to a reference year 2005 and the alkalinity estimated from the potential alkalinity versus salinity relationships. The climatological monthly mean values of pCO2 over the global ocean are compiled for a 4° x 5° grid for the reference year 2005, and the gridded data for each of 12 months are included in this database. This is updated version of Takahashi et al. (2009) for the reference year 2000 representing non-El Niño years using a database of about 6.5 million pCO2 data (less coastal areas of North and South America) observed in 1957-2012 (Takahashi et al., 2013). The equatorial zone (4°N-4°S) of the Pacific is excluded from the analysis because of the large interannual changes associated with the El Niño-Southern Oscillation events. The pH thus calculated ranges from 7.9 to 8.2. Lower values are located in the upwelling regions in the tropical Pacific and in the Arabian and Bering Seas; and higher values are found in the subpolar and polar waters during the spring-summer months of intense photosynthetic production. The vast areas of subtropical oceans have seasonally varying pH values ranging from 8.05 during warmer months to 8.15 during colder months. The warm tropical and subtropical waters are supersaturated by a factor of as much as 4.2 with respect to aragonite and 6.3 for calcite, whereas the cold subpolar and polar waters are less supersaturated only by 1.2 for aragonite and 2 for calcite because of the lower pH values resulting from greater TCO2 concentrations. In the western Arctic Ocean, aragonite undersaturation is observed.

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0164568 ARAGONITE SATURATION STATE CALCITE CONCENTRATION DISSOLVED INORGANIC CARBON (DIC) partial pressure of carbon dioxide - water pH total alkalinity carbon dioxide (CO2) gas analyzer pH sensor showerhead equilibrator titrator chemical physical surface underway Lamont-Doherty Earth Observatory Lamont-Doherty Earth Observatory Climate Variability and Predictability (CLIVAR) Ship of Opportunity Programme (SOOP) The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) World Ocean Circulation Experiment (WOCE) Indian Ocean North Atlantic Ocean North Pacific Ocean South Atlantic Ocean South Pacific Ocean oceanography COLUMBIA/LDEO > Lamont-Doherty Earth Observatory, Columbia University CLIVAR > Climate Variability WOCE > World Ocean Circulation Experiment Ocean Carbon Data System (OCADS) Project EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > ALKALINITY EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > CARBON DIOXIDE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > CARBONATE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > INORGANIC CARBON EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > PH Climatological Distributions of pH, pCO2, Total CO2, Alkalinity, and CaCO3 Saturation in the Global Surface Ocean NDP-094 pH, pCO2, Total CO2, Alkalinity, and CaCO3 Saturation CO2 ANALYZERS > CO2 ANALYZERS EQUILIBRATORS PH METERS > PH METERS OCEAN > ATLANTIC OCEAN > NORTH ATLANTIC OCEAN OCEAN > ATLANTIC OCEAN > SOUTH ATLANTIC OCEAN OCEAN > INDIAN OCEAN OCEAN > PACIFIC OCEAN > NORTH PACIFIC OCEAN OCEAN > PACIFIC OCEAN > SOUTH PACIFIC OCEAN

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