The World Ocean Database (WOD) is world's largest collection of uniformly formatted, quality controlled, publicly available ocean profile data. It is a powerful tool for oceanographic, climatic, and environmental research, and the end result of more than 20 years of coordinated efforts to incorporate data from institutions, agencies, individual researchers, and data recovery initiatives into a single database. WOD data spans from Captain Cook's 1772 voyage to the contemporary Argo period, making it a valuable resource for long term and historical ocean climate analysis. Original versions of the 20,000+ datasets in the WOD are available through the NCEI archives.
Use the WODselect retrieval system to search the WOD by specific parameters (date, geographic area, probe type, etc.) and measured variables. View a dataset distribution map and cast count of your search criteria, and download a custom dataset in WOD native, csv, or netCDF.
WOD data is also accessible through interfaces that sort data geographically and by date in native ASCII format.
For additional documentation and access methods, visit the dataset landing page.
The WOD consists of periodic major releases and quarterly updates to those releases. Each major release is associated with a concurrent release of the World Ocean Atlas (WOA), and contains final quality control flags used in the WOA, which includes manual as well as automated steps.
Each quarterly update release includes additional historical and recent data and preliminary quality control. The latest major release is World Ocean Database 2018 (WOD18), which includes more than 15.7 million oceanographic casts made up of 3.56 billion individual profile measurements.
Boyer, T.P., O.K. Baranova, C. Coleman, H.E. Garcia, A. Grodsky, R.A. Locarnini, A.V. Mishonov, C.R. Paver, J.R. Reagan, D. Seidov, I.V. Smolyar, K. Weathers, M.M. Zweng,(2018): World Ocean Database 2018. A.V. Mishonov, Technical Ed., NOAA Atlas NESDIS 87. https://www.ncei.noaa.gov/sites/default/files/2020-04/wod_intro_0.pdf
Boyer, T.P., J.I. Antonov, O.K. Baranova, C. Coleman, H.E. Garcia, A. Grodsky, D.R. Johnson, R.A. Locarnini, A.V. Mishonov, T.D. O'Brien, C.R. Paver, J.R. Reagan, D. Seidov, I.V. Smolyar, and M.M. Zweng, 2013: World Ocean Database 2013., S. Levitus, Ed., A. Mishonov, Technical Ed.; NOAA Atlas NESDIS 72, 209 pp., doi:10.7289/V5NZ85MT.
Boyer, T.P., J.I. Antonov , O.K. Baranova, H.E. Garcia, D.R. Johnson, R.A. Locarnini, A.V. Mishonov, T. D. O’Brien, D. Seidov, I.V. Smolyar, M.M. Zweng, 2009. World Ocean Database 2009 S. Levitus, Ed., NOAA Atlas NESDIS 66, 216 pp. https://repository.library.noaa.gov/view/noaa/1195
Boyer, T.P., J.I. Antonov, H.E. Garcia, D.R. Johnson, R.A. Locarnini, A.V. Mishonov, M T. Pitcher, O.K. Baranova, I.V. Smolyar, 2006. World Ocean Database 2005. S. Levitus, Ed., NOAA Atlas NESDIS 60, 190 pp., https://repository.library.noaa.gov/view/noaa/1131
Boyer, T.P., O.K. Baranova, C. Coleman, H.E. Garcia, A. Grodsky, R.A. Locarnini, A.V. Mishonov, C.R. Paver, J.R. Reagan, D. Seidov, I.V. Smolyar, K. Weathers, M.M. Zweng,(2018): World Ocean Database 2018. A.V. Mishonov, Technical Ed., NOAA Atlas NESDIS 87.
Garcia, H. E., T. P. Boyer, R. A. Locarnini, O. K. Baranova, M. M. Zweng (2018). World Ocean Database 2018: User’s Manual (prerelease). A.V. Mishonov, Technical Ed., NOAA, Silver Spring, MD.
The oceanographic data that comprise the WOD have been acquired through many sources and projects as well as from individual scientists. In addition, many international organizations such as the IODE/GODAR and WDS have facilitated data exchanges, which have provided much data to the WOD. The World Ocean Database (WOD) is an NCEI product and an IODE (International Oceanographic Data and Information Exchange) project. This work is funded in partnership with the NOAA OAR Global Ocean Monitoring (GOMO).
The WOD is made up of ocean profiles, which contain measurements for a single variable (temperature, salinity, etc.) taken from one location at different depths, or a horizontal string of readings taken from the surface. WOD profiles must contain more than a single depth/variable pair. Multiple profiles taken at the same location with the same set of instruments form an oceanographic cast.
Consult the WOD Introduction for a full set of definitions, and the WOD User’s Manual for a description of fields and codes.
Code tables necessary to use the World Ocean Database data.
Data masks delineating ocean areas, range basins, and 5-degree standard deviation.
range_area.msk Ocean areas for each set of variable min/max ranges range_basin_list.msk Range basins list sd_multiplier.msk 5-degree standard deviation multiplier
Use these programs to read WOD data, or convert it from WOD format to tabular column or comma separated columns (.csv)
wod_nc.f Sample FORTRAN program for reading WOD ragged array netCDF files readFOR.txt Readme file describes the wodFOR programs wodFOR.f Sample FORTRAN program for reading the data sampFOR.txt Sample of output from wodFOR.f readASC.txt Describes the use of wodASC.f wodASC.f Outputs a user selected variable in either tabular or comma separated columns wodASC.exe Executable for wodASC.f program sampASC.txt Sample output data from wodASC.f wodSUR.f Writes surface-only data out in a comma-separated-value (CSV) format wodSUR.exe Microsoft compatible executable for wodSUR.f sampSUR.txt Sample of output from wodSUR.exe instructions from WOD to csv Instructions to convert WOD format to ArcMap readable 'csv' format csvfromwod.c (β - version) C program for conversion data from WOD format to ArcMap readable 'csv' format csvfromwod.exe Executable for C program ArcGIS tutorial Tutorial to convert 'csv' files in to shapefiles and upload it in ArcMap readC.txt Readme file describing the wodC program wodC.c Sample C program for reading the data wodC.exe Executable for C program wodtodepthmatrix_info.txt Info file describing the wodtodepthmatrix.c program wodtodepthmatrix.c Sample C program for reading the data Wodtodepthmatrix.exe Executable for wodtodepthmatrix.exe program (for Windows 64bit system)
Quality control procedures are documented and performed on each cast and the results are included as flags on each measurement. The WOD contains the data on the originally measured depth levels (observed) and also interpolated to standard depth levels to present a more uniform set of iso-surfaces for oceanographic and climate work.
The WOD is made up of more than 20,000 separate archived datasets from the United States and around the world, each of which is available in its original form in the NCEI archives. All datasets are converted to the same standard format, checked for duplication within the WOD, and assigned quality flags based on objective tests. Additional subjective flags are set upon calculation of ocean climatological mean fields which make up the World Ocean Atlas (WOA) series.
For additional help, please contact OCL.help@noaa.gov.
To download WOD in native ASCII, use the following command: wget -N -nH -nd -r -e robots=off --no-parent --force-html https://data.nodc.noaa.gov/woa/WOD/YEARLY/.
For netCDF format, mark all years in WODselect (1773-2018), and request the data in netCDF. You will receive an email with files attached once your request is processed.
How long are my requested files available on the FTP site? Files are removed from the FTP site 3 days after they are created. Can I use the cruise ID number to find cruise attributes? In WODselect:
Example: US029567. Click the accession# for the link to the Archive System.
A number of floats in the North Atlantic had a pressure offset problem which was not correctable. The Argo program removed these floats from their dataset, and we followed their example.
How can I calculate the apparent oxygen utilization (AOU) in the deep ocean? Use the saturation oxygen content calculated using potential temperature with respect to the surface, minus the dissolved oxygen measured at depth. How is the Surface Only Dataset (SUR) organized? The WOD Surface-Only Dataset is a set of single profile casts that contains all the surface-only data from an entire cruise. The individual levels of the surface-only form are distinct surface measurement sets from a given date/position. The cruise will span a time period from days to months rather than the single date/time of a profile cast. For this reason, surface-only data are in a single file rather than split out by year in the YEARLY directory, or by position in the GEOGRAPHIC directory. Is there a time variable in WOD?
WOD time variables are listed in UTC format, and unspecified times are assumed to be UTC until otherwise proven.
As with all data, time zone information is not always correctly reported. We use quality control measure to correct common errors, including UTC designations that should be labeled as local time.
Does the WOD netCDF file contain information about the chlorophyll measuring method used?
Second Header variables in the netCDF file identify collection and processing methods used for the various parameters. For chlorophyll, we identify a whole suite of methods that range from in situ fluorometer to HPLC. The codes are listed below:
Many of the chlorophyll measurements in CTD datasets are uncalibrated fluorometer readings that are often still in engineering units. These data have to be read very carefully, and can only be evaluated on a cruise by cruise basis. There is a calibration indicator (variable specific second header 14), but this information is rarely included with the data.
More information is available on page 19 of the World Ocean Database 2018 Introduction.
Regardless of the depth calculation method, all profiles are interpolated to the standard World Ocean Atlas standard depths.
Explain the output format for WOD-reading programs
Output generally includes ocean parameters, number of significant digits stored, and QC flags. The parenthetical value states the number of significant digits in the measurement directly to its left. The same is true for second headers. The two bracketed numbers are single digit quality flags; one set by the WOD, and the other by the originator.
Note: The program only prints the first 3 decimal places, but the full value to the given significant figures is stored in the file’s array read.
Learn more about output format in the WOD User Manual, and consult WOD codes for specific flag values.
Which methods are used to measure nutrient data?
There isn’t a definitive set of methods for measuring or calculating nutrient data. From page 45 of the WOD Introduction:
It is difficult to estimate the precision and reproducibility of the historical chemical data in part because (1) there has not been a generally accepted set of standard international analytical oceanographic methods; (2) there has been a continuous availability over time of new or improved analytical techniques for the sampling and determination of the concentration of dissolved and particulate constituents in seawater; (3) there is the practical difficulty of periodic comparison of the precision and accuracy of oceanographic data collected by oceanographic institutions worldwide. At present, we are not aware of a suitable monitoring program for the systematic comparison of analytical instruments, measurements, and certified reference standards used by international research Institutions or Universities to collect oceanographic observations.
We do include information on the method used for nutrient (and other) data when it is available. Variable description for the second header 6 may be found on WOD codes page, or accessed directly through the methods list.
What is the file format for Global Ocean Heat and Salt Content? Officially archived versions of the fields are stored in Climate-Forecast (CF) compliant netCDF. See section 5, page 8 of World Ocean Atlas 2018 documentation for more details, other available formats. Why is there an inconsistency between the 5-year and shorter average ocean heat anomalies? The 5 year period is actually a composite calculated from the mean anomaly in each 1 degree grid square over a 5-year period using all measurements from that 5 year stretch. There’s a discrepancy between the 5 year composite and shorter periods, because the shorter means are based on conservative estimates due to limited data coverage. The 5-year composite mean typically has better data coverage, which allows for a less cautious, more precise estimate. How is heat content calculated?
Temperature anomalies are calculated at 16 standard depths from 0-700m (or 26 standard depths 0-2000m) by subtracting observed (interpolated) temperatures from the long-term (1955-2018) climatological monthly mean. The mean of all temperature anomalies is calculated at each standard depth for every box on the grid. The temperature anomaly represents the volume of water that makes up the vertical distance from halfway between the next shallower depth and the given standard depth to halfway between the next deeper depth and the given standard depth.
The temperature anomaly is multiplied by the climatological mean density of the one-degree square and the heat capacity of water and the area and volume of the one-degree square for the given standard depth. The heat contents for each volume surrounding a standard depth are summed to calculate full ocean heat content anomaly for each one degree gridbox. The values for each gridbox are summed to calculate global value. [Note this is a global integral, not an average.] The area of each one-degree gridbox is calculated similar to the attached FORTRAN subroutine (easily adaptable to any software language).
The land/sea mask used to decide whether a one-degree gridbox is land or ocean (the one-degree, not quarter-degree) is derived from the ETOPO2 altitude/bathymetry data set. This same land/sea mask is used to determine whether the volume of a given one-degree square extends to the bottom of the integration level (700 m or 2000 m) or to a shallower depth. Because ocean temperature measurements are relatively sparse at the subsurface level, we use an objective analysis technique to calculate a complete set of one-degree temperature anomaly data at each standard depth after the anomalies from existing data are calculated. From there the heat content is calculated. The objective analysis technique is described in a number of publications, including WOA18 Temperature.
Does the dataset include yearly salt content data? We have pentadal salinity anomalies back to 1955. See Global Heat and Salt Content , but yearly data only spans the Argo time period (i.e., 2005 onward) and is available on the salinity anomaly page. What are the units for 0-700 m heat content? The value of J/m**2 is multiplied by the grid area over which the heat content is calculated, resulting in final units of joules [J]. What is the halosteric component of sea level rise? Halosteric change is the change in sea level due to the effects of salinity change on seawater density.
