Data Sets and Methods
In order to interpolate the measured TCO2 and TALK data, the available observations were assembled (Table 1). Measurements prior to 1990 did not use the accurate standards established by Dickson (1997) for calibrating TCO2. Therefore pre-1990 profiles were adjusted by comparing deep measurements within 1° of latitude and longitude, as described for the Atlantic Ocean (Goyet et al. 1997), the Pacific Ocean (Feely et al. 1998), and the Indian Ocean (Sabine et al. 1999).
All the TALK measurements were performed by potentiometry (Dyrssen 1965; Millero et al. 1998). Most of the TCO2 measurements were performed by extraction/coulometry (Johnson et al. 1985, 1987, 1993, 1998) except for the cruises prior to 1990 where TCO2 was measured by potentiometry. All these measurements are described in detail in the Handbook of Methods for the Analysis of the Various Parameters of the Carbon Dioxide System in Sea Water (DOE 1994).
Table 1. Summary of data sets used for interpolation of the TCO2 and TALK fields on the global scale
|GEOSECS1||Takahashi et al. 1980|
|INDIGO2||Poisson et al. 1988, 1989, 1990|
|TTO5||Data reports, TTO 1986a,b|
|WOCE6; SAVE7||CDIAC; http://cdiac.ornl.gov/oceans/|
1 Geochemical Ocean Sections
2 Indian Ocean Global Observation
3 Joint Global Ocean Flux Study
4 Ocean-Atmosphere Carbon Exchange Study
5 Transient Tracers in the Ocean
6 World Ocean Circulation Experiment
7 South Atlantic Ventilation Experiment
8 National Oceanographic and Atmospheric Administration