Global Ocean Data Analysis Project: Difference between revisions

Revision as of 09:59, 14 February 2018

Revision as of 10:02, 14 February 2018

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==Dataset==

The GLODAPGLODAPv1.1 climatology contains analysed fields of "present day" (1990s) [[Total inorganic carbon|dissolved inorganic carbon]] (DIC), [[alkalinity]], [[carbon-14]] (¹⁴C), [[CFC-11]] and [[CFC-12]].<ref>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</ref> The fields consist of [[Three-dimensional space|three-dimensional]], objectively-analysed global grids at 1° [[Image resolution#Spatial resolution|horizontal resolution]], interpolated onto 33 standardised [[water column|vertical intervals]]<ref>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</ref> from the surface (0 m) to the [[Abyssal zone|abyssal]] [[Seabed|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 [[Maritime Southeast Asia]].

Additionally, analysis has attempted to separate natural from anthropogenic DIC, to produce fields of pre-[[industrial revolution|industrial]] (18th century) DIC and "present day" anthropogenic CO₂. This separation allows estimation of the magnitude of the ocean [[carbon dioxide sink|sink]] for anthropogenic CO₂, and is important for studies of phenomena such as [[ocean acidification]].<ref name=orr05>Orr, 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.] {{webarchive |url=https://web.archive.org/web/20080625000000/http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Orr_OnlineNature04095.pdf |date=June 25, 2008 }} ''Nature'' '''437''', 681-686</ref><ref name=raven05>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</ref> 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)<ref>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</ref> to [[deconvolution|deconvolute]] anthropogenic from natural DIC (there are a number of alternative methods). 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.<ref name=orr05/><ref>{{cite journal | last1 = Matsumoto | first1 = K. | last2 = Gruber | first2 = N. | title = How accurate is the estimation of anthropogenic carbon in the ocean? An evaluation of the DC* method | journal = Global Biogeochem. Cycles | volume = 19 | date = 2005 | doi = 10.1029/2004GB002397 |bibcode = 2005GBioC..19.3014M }}</ref>

The GLODAPv2 climatology largely repeats the earlier format, but makes use of the large number of observations of the ocean's carbon cycle made over the intervening period (2000—2013). The analysed "present-day" fields in the resulting dataset are [[Normalization (statistics)|normalised]] to year 2002.

==Gallery==