View source for Global Ocean Data Analysis Project

{{short description|Synthesis project bringing together biogeochemical oceanographic data}}
The '''Global Ocean Data Analysis Project''' ('''GLODAP''') is a synthesis project bringing together [[oceanography|oceanographic]] data, featuring two major releases as of 2018. 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 [[greenhouse gas|anthropogenically forced]] states.  GLODAP is funded by the [[National Oceanic and Atmospheric Administration]], the [[United States Department of Energy|U.S. Department of Energy]], and the [[National Science Foundation]].

The first GLODAP release (v1.1) was produced from data collected during the 1990s by research cruises on the [[World Ocean Circulation Experiment]], [[Joint Global Ocean Flux Study]] and [[Ocean-Atmosphere Exchange Study]] programmes. The second GLODAP release (v2) extended the first using data from cruises from 2000 to 2013. The data are available both as individual "bottle data" from sample sites, and as interpolated fields on a standard longitude, latitude, depth grid.

==Dataset==
The GLODAPv1.1 climatology contains analysed fields of "present day" (1990s) [[Total inorganic carbon|dissolved inorganic carbon]] (DIC), [[alkalinity]], [[carbon-14]] (<sup>14</sup>C), [[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/20080625100559/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.] {{Webarchive|url=https://web.archive.org/web/20070927215722/http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13314 |date=2007-09-27 }} 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 disequilibrium 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 | issue = 3 | doi = 10.1029/2004GB002397 |bibcode = 2005GBioC..19.3014M | s2cid = 3468049 | doi-access = free }}</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).<ref name="olsen2016">{{cite journal |last1=Olsen |first1=A. |last2=Key |first2=R.M. |last3=van Heuven |first3=S. |last4=Lauvset |first4=S.K. |last5=Velo |first5=A. |last6=Lin |first6=X. |last7=Schirnick |first7=C. |last8=Kozyr |first8=A. |last9=Tanhua |first9=T. |last10=Hoppema |first10=M. |last11=Jutterström |first11=S. |last12=Steinfeldt |first12=R. |last13=Jeansson |first13=E. |last14=Ishii |first14=M. |last15=Pérez |first15=F.F. |last16=Suzuki |first16=T. |date=2016 |title=The Global Ocean Data Analysis Project version 2 (GLODAPv2) – an internally consistent data product for the world ocean |journal=Earth System Science Data |volume=8 |issue= 2|pages=297–323 |doi=10.5194/essd-8-297-2016 |bibcode=2016ESSD....8..297O |doi-access=free |hdl=10261/135582 |hdl-access=free }}</ref><ref name="lauvset2016">{{cite journal |last1=Lauvset |first1=S.K. |last2=Key |first2=R.M. |last3=Olsen |first3=A. |last4=van Heuven |first4=S. |last5=Velo |first5=A. |last6=Lin |first6=X. |last7=Schirnick |first7=C. |last8=Kozyr |first8=A. |last9=Tanhua |first9=T. |last10=Hoppema |first10=M. |last11=Jutterström |first11=S. |last12=Steinfeldt |first12=R. |last13=Jeansson |first13=E. |last14=Ishii |first14=M. |last15=Pérez |first15=F.F. |last16=Suzuki |first16=T. |last17=Watelet |first17=S. |date=2016 |title=A new global interior ocean mapped climatology: the 1° × 1° GLODAP version 2 |journal=Earth System Science Data |volume=8 |issue= 2|pages=325–340 |doi=10.5194/essd-8-325-2016 |bibcode=2016ESSD....8..325L |doi-access=free |hdl=10261/135584 |hdl-access=free }}</ref> The analysed "present-day" fields in the resulting dataset are [[Normalization (statistics)|normalised]] to year 2002. Anthropogenic carbon was estimated in GLODAPv2 using a "transit-time distribution" (TTD) method (an approach using a [[Green's function]]).<ref name="waugh2006">{{cite journal |last1=Waugh |first1=D.W. |last2=Hall |first2=T.M. |last3=McNeil |first3=B.I. |last4=Key |first4=R. |last5=Matear |first5=R.J. |date=2006 |title=Anthropogenic CO<sub>2</sub> in the oceans estimated using transit-time distributions |journal=Tellus |volume=58B |issue= 5|pages=376–390 |doi=10.1111/j.1600-0889.2006.00222.x |bibcode=2006TellB..58..376W |doi-access=free }}</ref><ref name="lauvset2016"/> In addition to updated fields of DIC (total and anthropogenic) and alkalinity, GLODAPv2 includes fields of seawater [[pH]] and [[calcium carbonate]] [[Saturated solution|saturation state]] (Ω; omega). The latter is a non-dimensional number calculated by dividing the local [[carbonate]] ion concentration by the ambient saturation concentration for calcium carbonate (for the [[Biomineralization|biomineral]] [[Polymorphism (materials science)|polymorphs]] [[calcite]] and [[aragonite]]), and relates to an oceanographic property, the [[carbonate compensation depth]]. Values of this below 1 indicate [[undersaturation]], and potential dissolution, while values above 1 indicate [[supersaturation]], and relative stability.

==Gallery==
The following panels show sea surface concentrations of fields prepared by GLODAPv1.1. The "pre-industrial" is the 18th century, while "present-day" is approximately the 1990s.
{| border="0" style="margin:1em auto;"
|-
| [[File:Estimated annual mean sea surface dissolved inorganic carbon for the 1700s (GLODAP).png|thumb|Pre-industrial DIC]]
| [[File:Annual mean sea surface dissolved inorganic carbon for the 1990s (GLODAP).png|thumb|"Present day" DIC]]
| [[File:Annual mean sea surface anthropogenic dissolved inorganic carbon concentration (GLODAP).png|thumb|"Present day" anthropogenic {{CO2}}]]
|-
| [[File:WOA05 GLODAP pd ALK AYool.png|thumb|"Present day" alkalinity]]
| [[File:GLODAP sea-surf CFC11 AYool.png|thumb|"Present day" CFC-11]]
| [[File:GLODAP sea-surf CFC12 AYool.png|thumb|"Present day" CFC-12]]
|-
|}

The following panels show sea surface concentrations of fields prepared by GLODAPv2. The "pre-industrial" is the 18th century, while "present-day" is normalised to 2002. Note that these properties are shown in [[mass]] units (per kilogram of seawater) rather than the [[volume]] units (per cubic metre of seawater) used in the GLODAPv1.1 panels.
{| border="0" style="margin:1em auto;"
|-
| [[File:Surface ocean pre-industrial DIC concentration, GLODAPv2.png|thumb|Surface ocean pre-industrial DIC concentration, GLODAPv2]]
| [[File:Surface ocean present-day DIC concentration, GLODAPv2.png|thumb|Surface ocean present-day DIC concentration, GLODAPv2]]
| [[File:Surface ocean anthropogenic CO2 concentration, GLODAPv2.png|thumb|Surface ocean anthropogenic CO2 concentration, GLODAPv2]]
|-
| [[File:Surface ocean present-day total alkalinity, GLODAPv2.png|thumb|Surface ocean present-day total alkalinity, GLODAPv2]]
| [[File:Surface ocean present-day pH, GLODAPv2.png|thumb|Surface ocean present-day pH, GLODAPv2]]
| [[File:Surface ocean present-day omega calcite, GLODAPv2.png|thumb|Surface ocean present-day omega calcite, GLODAPv2]]
|-
|}

==See also==
{{portal|Oceans}}
* [[Biogeochemical cycle]]
* [[Biological pump]]
* [[Continental shelf pump]]
* [[Geochemical Ocean Sections Study]]
* [[Joint Global Ocean Flux Study]]
* [[Ocean acidification]]
* [[Solubility pump]]
* [[World Ocean Atlas]]
* [[World Ocean Circulation Experiment]]

==References==
{{reflist}}

==External links==
* [https://www.glodap.info/ GLODAP website], [[Bjerknes Centre for Climate Research|Bjerknes Climate Data Centre]]
* [https://www.nodc.noaa.gov/ocads/oceans/glodap/ GLODAP v1.1 website], [[National Oceanic and Atmospheric Administration]]
* [https://www.nodc.noaa.gov/ocads/oceans/GLODAPv2/ GLODAP v2 website], National Oceanic and Atmospheric Administration

{{physical oceanography}}

[[Category:Biological oceanography]]
[[Category:Carbon]]
[[Category:Chemical oceanography]]
[[Category:Chlorofluorocarbons]]
[[Category:Oceanography]]
[[Category:Physical oceanography]]