Global Ocean Data Analysis Project

The Global Ocean Data Analysis Project (GLODAP) is a synthesis project bringing together oceanographic data collected during the 1990s by research cruises on the World Ocean Circulation Experiment (WOCE), Joint Global Ocean Flux Study (JGOFS) and Ocean-Atmosphere Exchange Study (OACES) programmes. The central goal of GLODAP is to generate a global climatology of the World Ocean's carbon cycle for use in studies of both its natural and anthropogenically-forced states. GLODAP is funded by the National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of Energy (DOE), and the National Science Foundation (NSF).

Dataset

The GLODAP climatology contains analysed fields of "present day" (1990s) dissolved inorganic carbon (DIC), alkalinity, carbon-14 (¹⁴C), CFC-11 and CFC-12 [Key, R.M., Kozyr, A., Sabine, C.L., Lee, K., Wanninkhof, R., Bullister, J., Feely, R.A., Millero, F., Mordy, C. and Peng, T.-H. (2004). A global ocean carbon climatology: Results from GLODAP. "Global Biogeochemical Cycles" 18, GB4031] . The fields consist of three-dimensional, objectively-analysed global grids at 1° horizontal resolution, interpolated onto 33 standardised vertical intervals [Standardised intervals are at 0, 10, 20, 30, 50, 75, 100, 125, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1750, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500 m] from the surface (0 m) to the seafloor (5500 m). In terms of temporal resolution, the relative scarcity of the source data mean that, unlike the World Ocean Atlas, averaged fields are only produced for the annual time-scale. The GLODAP climatology is missing data in certain oceanic provinces including the Arctic Ocean, the Caribbean Sea, the Mediterranean Sea and the Malay Archipelago.

Additionally, analysis has attempted to separate natural from anthropogenic DIC, to produce fields of pre-industrial (1700s) DIC and "present day" anthropogenic CO₂. This separation allows estimation of the magnitude of the ocean sink for anthropogenic CO₂, and is important for studies of phenomena such as ocean acidificationOrr, J. C. "et al." (2005). [http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Orr_OnlineNature04095.pdf Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.] "Nature" 437, 681-686] Raven, J. A. "et al." (2005). [http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13314 Ocean acidification due to increasing atmospheric carbon dioxide.] Royal Society, London, UK] . However, as anthropogenic DIC is chemically and physically identical to natural DIC, this separation is difficult. GLODAP used a mathematical technique known as C* (C-star) [Gruber, N., Sarmiento, J.L. and Stocker, T.F. (1996). An improved method for detecting anthropogenic CO₂ in the oceans, "Global Biogeochemical Cycles" 10:809– 837] to deconvolute anthropogenic from natural DIC (this is only one of several similar approaches). This uses information about ocean biogeochemistry and CO₂ surface disequilibium together with other ocean tracers including carbon-14, CFC-11 and CFC-12 (which indicate water mass age) to try to separate out natural CO₂ from that added during the ongoing anthropogenic transient. The technique is not straightforward and has associated errors, although it is gradually being refined to improve it. Its findings are generally supported by independent predictions made by dynamic models.

Gallery

The following panels show sea surface concentrations of the fields prepared by GLODAP.

References

ee also

* Biological pump
* Continental shelf pump
* Ocean acidification
* Solubility pump
* World Ocean Atlas
* World Ocean Circulation Experiment

External links

* [http://cdiac.esd.ornl.gov/oceans/glodap/Glopintrod.htm GLODAP website]