Simple Ocean Data Assimilation: Difference between revisions

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{{short description|Oceanic reanalysis data set consisting of gridded state variables for the global ocean}}

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The '''Simple Ocean Data Assimilation''' (SODA)''' analysis is an [[Ocean reanalysis|oceanic reanalysis]] data set consisting of gridded [[Statestate variable|state variables]]s for the global ocean, as well as several derived fields. SODA was developed in the 1990s as a collaborative project between the Department of Atmospheric and Oceanic Science at the University of Maryland and the Department of Oceanography at Texas A&M University with the goal of providing an improved estimate of ocean state from those based solely on observations or numerical simulations. Since its first release there have been several updates, the most recent of which extends from 1958- to 2008, as well as a “beta release” of a long-term reanalysis for 1871-20081871–2008.

==Initial release==

The '''Simple Ocean Data Assimilation (SODA)''' analysis is an [[Ocean reanalysis|oceanic reanalysis]] data set consisting of gridded [[State variable|state variables]] for the global ocean, as well as several derived fields. SODA was developed in the 1990s as a collaborative project between the Department of Atmospheric and Oceanic Science at the University of Maryland and the Department of Oceanography at Texas A&M University with the goal of providing an improved estimate of ocean state from those based solely on observations or numerical simulations. Since its first release there have been several updates, the most recent of which extends from 1958-2008, as well as a “beta release” of a long-term reanalysis for 1871-2008.

Initially released in 2000, SODA included data from the 1994 [[World Ocean Atlas]] (WOA-94) such as MBT, [[Expendable bathythermograph|XBT]], [[Conductivity, temperature, depth|CTD]] and station data; hydrography, SST, and altimeter measured sea level; as well as data from [[National Oceanographic Data Center|NODC]], [[National Centers for Environmental Prediction|NCEP]], and [[Tropical Ocean Global Atmosphere program|TOGA]]-[[Tropical Atmosphere Ocean project|TAO]]. The spatial extend of the first release was more limited than subsequent releases, extending from 62°S to 62°N, and covering the time period from January 1950 through December 1995.<ref name=cg2000> Carton, J.A., G. Chepurin, X. Cao, B. Giese, 2000: A Simple Ocean Data Assimilation Analysis of the Global Upper Ocean 1950–95. Part I: Methodology. ''J. Phys. Oceanogr. '', '''30''', 294–309.</ref>

==InitialCurrent Releaserelease==

The latest release of SODA (SODA 2.1.6) covers the time period from January 1958 to December 2008. As part of the [[Data assimilation|data assimilation]] scheme, the system ingests a wide variety of observations including hydrographic profiles, ocean station data, moored temperature and salinity measurements, surface temperature and salinity observations from a variety of instruments (e.g., MBT, XBT, CTD), [[sea surface temperature]] (SST) from nighttime infrared observations from satellites, and satellite based sea level altimetry. Additionally, the numerical model used for forecasts is driven by surface winds from the [[European Centre for Medium-Range Weather Forecasts|European Center for Medium-Range Weather Forecasts]] [[ERA-40]] reanalysis data set during the period between 1958- and 2001,<ref name=cg2008> Carton, J.A. and B. Giese, 2008: A Reanalysis of Ocean Climate Using Simple Ocean Data Assimilation (SODA). ''Mon. Weath. Rev. '', '''136''', 2999-3017.</ref> and from the [[QuickSCAT]] scatterometer for 2002-20082002–2008.<ref name=cg2005> Carton, J.A. and B. Giese, 2005: SODA: A Reanalysis of Ocean Climate. [online] Available at: <http://www.atmos.umd.edu/~carton/pdfs/carton&giese05.pdf> [Accessed 26 November 2012].</ref> The state variable forecasts used in the assimilation are calculated using a general circulation model based on [[Parallel Ocean Program]] numerics with an average horizontal resolution of 0.25°x0.4°, and 40 vertical layers, which have 10-meter vertical resolution near the surface. Starting with version 1.4.2, the ocean model is run using a displaced pole grid configuration, allowing for the representation of [[Arctic Ocean]] processes. The data assimilation method used is based on a sequential analysis with a 10-day update cycle. <ref name=cg2008/>

The reanalysis data is packaged into monthly means from January 1958 to December 2008 (although five -day means are also available) and stored in [[NetCDF]] format. Standard state variables were calculated including temperature, salinity, zonal and meridional velocities, and sea level, as well as several derived fields such as heat content. Finalized data was remapped from the displaced pole grid to a uniform horizontal grid with 0.5°x0.5° horizontal resolution and 40 vertical layers with 10-meter vertical resolution near the surface. <ref name=cg2008/>

Initially released in 2000, SODA included data from the 1994 [[World Ocean Atlas]] (WOA-94) such as MBT, [[Expendable bathythermograph|XBT]], [[Conductivity, temperature, depth|CTD]] and station data; hydrography, SST, and altimeter measured sea level; as well as data from [[National Oceanographic Data Center|NODC]], [[National Centers for Environmental Prediction|NCEP]], and [[Tropical Ocean Global Atmosphere program|TOGA]]-[[Tropical Atmosphere Ocean project|TAO]]. The spatial extend of the first release was more limited than subsequent releases, extending from 62°S to 62°N, and covering the time period from January 1950 through December 1995.<ref name=cg2000> Carton, J.A., G. Chepurin, X. Cao, B. Giese, 2000: A Simple Ocean Data Assimilation Analysis of the Global Upper Ocean 1950–95. Part I: Methodology. ''J. Phys. Oceanogr. '', '''30''', 294–309.</ref>

In addition to the 61-year reanalysis data set, a “beta” version (i.e., currently being evaluated), SODA 2.2.4, was released in 2010 and extends from 1871 to 2008 with monthly temporal resolution. This extended analysis is identical in horizontal and vertical spatial resolution as the standard reanalysis data set (SODA 2.1.6), and includes similar output variables.<ref name=IRIDL> IRI Data Library, 2012. ''Carton-Giese SODA SODA 2.2.4, 1871-2008 Assimilation Run''. [online] Available at: <http://iridl.ldeo.columbia.edu/SOURCES/.CARTON-GIESE/.SODA/.v2p2p4/> [Accessed 26 NoevemberNovember 2012]. </ref>

==Current Release==

==See Alsoalso==

The latest release of SODA (SODA 2.1.6) covers the time period from January 1958 to December 2008. As part of the [[Data assimilation|data assimilation]] scheme, the system ingests a wide variety of observations including hydrographic profiles, ocean station data, moored temperature and salinity measurements, surface temperature and salinity observations from a variety of instruments (e.g., MBT, XBT, CTD), sea surface temperature (SST) from nighttime infrared observations from satellites, and satellite based sea level altimetry. Additionally, the numerical model used for forecasts is driven by surface winds from the [[European Centre for Medium-Range Weather Forecasts|European Center for Medium-Range Weather Forecasts]] [[ERA-40]] reanalysis data set during the period between 1958-2001,<ref name=cg2008> Carton, J.A. and B. Giese, 2008: A Reanalysis of Ocean Climate Using Simple Ocean Data Assimilation (SODA). ''Mon. Weath. Rev. '', '''136''', 2999-3017.</ref> and from the [[QuickSCAT]] scatterometer for 2002-2008.<ref name=cg2005> Carton, J.A. and B. Giese, 2005: SODA: A Reanalysis of Ocean Climate. [online] Available at: <http://www.atmos.umd.edu/~carton/pdfs/carton&giese05.pdf> [Accessed 26 November 2012].</ref> The state variable forecasts used in the assimilation are calculated using a general circulation model based on [[Parallel Ocean Program]] numerics with an average horizontal resolution of 0.25°x0.4°, and 40 vertical layers, which have 10-meter vertical resolution near the surface. Starting with version 1.4.2, the ocean model is run using a displaced pole grid configuration, allowing for the representation of [[Arctic Ocean]] processes. The data assimilation method used is based on a sequential analysis with a 10-day update cycle. <ref name=cg2008/>

The reanalysis data is packaged into monthly means from January 1958 to December 2008 (although five day means are also available) and stored in [[NetCDF]] format. Standard state variables were calculated including temperature, salinity, zonal and meridional velocities, and sea level, as well as several derived fields such as heat content. Finalized data was remapped from the displaced pole grid to a uniform horizontal grid with 0.5°x0.5° horizontal resolution and 40 vertical layers with 10-meter vertical resolution near the surface. <ref name=cg2008/>

In addition to the 61-year reanalysis data set, a “beta” version (i.e., currently being evaluated), SODA 2.2.4, was released in 2010 and extends from 1871 to 2008 with monthly temporal resolution. This extended analysis is identical in horizontal and vertical spatial resolution as the standard reanalysis data set (SODA 2.1.6), and includes similar output variables.<ref name=IRIDL> IRI Data Library, 2012. ''Carton-Giese SODA SODA 2.2.4, 1871-2008 Assimilation Run''. [online] Available at: <http://iridl.ldeo.columbia.edu/SOURCES/.CARTON-GIESE/.SODA/.v2p2p4/> [Accessed 26 Noevember 2012]. </ref>

==See Also==

*[[NCEP/NCAR Reanalysis|NECP/NCAR reanalysis]]

*[[ECMWF re-analysis|ECMWF reanalysis]]

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{{reflist}}

==External Linkslinks==

*[http://www.atmos.umd.edu/~ocean/] University of Maryland SODA Webpage

*[https://web.archive.org/web/20141023005938/http://www.atmos.umd.edu/~ocean/soda1.2.pdf] SODA Description for CLIVAR

*[http://www.atmos.umd.edu/~carton/index2_files/soda.htm] List of SODA experiments

*[http://soda.tamu.edu/] Texas A&M University SODA Webpage

*[http://iridl.ldeo.columbia.edu/SOURCES/.CARTON-GIESE/.SODA/] Data access via the IRI Data Library

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[[Category:Oceanography]]