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Downloading, decompressing, and reading WODselect data

For technical help or to report problems, please e-mail OCL.help@noaa.gov

The WODselect interface allows a user to search World Ocean Database (WOD) using a variety of user-specified search criteria. The search criteria will yield a geographic distribution map and cast count and the option to have the data extracted and placed on the NODC FTP site either in the WOD native ASCII or comma separated value (".csv") data format. The WOD data format description can be found in detail in the WOD documentation. After the data have been selected and extracted to the NODC FTP site, the user will receive e-mail notification that their data are ready and a link to retrieve the data selected. The user should be aware that WOD data also are available presorted by 10° geographic squares and by year.

Downloading multiple netCDF data files:
All the WOD netCDF files are uncompressed. Multiple netCDF files can be downloaded using the 'wget' command line tool.

UNIX USERS: Can download the data files by typing the following command line:
wget -N -nH -nd -r -e robots=off --no-parent --force-html -A.nc https://www.ncei.noaa.gov/data/oceans/woa/ [path to data files location]/.
For example, to get the WOA18 temperature files for 5564 decade, use the following command line:
wget -N -nH -nd -r -e robots=off --no-parent --force-html -A.nc https://www.ncei.noaa.gov/data/oceans/woa/WOA18/DATA/temperature/netcdf/5564/

WINDOWS USERS: Can download wget software for windows at wget software for windows.

Downloading individual data files:
All the WODselect ASCII output files are in GZIP compressed format. However, the user should be aware that different web browsers handle GZIP compressed files differently.

MOZILLA USERS: Can download the data file in two ways: (1) hold the "shift" key and click on the link to the data file or (2) right-mouse click on the link and select the "Save Link Target As ..." option.

INTERNET EXPLORER USERS: Can download the data file by copying the link location to your browser and then saving the file in your local working directory.

Decompressing data:
After downloading the data file, to uncompress the file the user can use any software which can handle zip-archives, such as WinZip, WinRAR, StuffIt, MacZip, UnZip, etc. After downloading and uncompressing the file, you can view the data using any ASCII text editor.

Reading WOD native data format:
The WOD data format description can be found in the WOD documentation. The data format is comprised of several sections including primary, secondary, variable-specific second headers, character data, taxa-specific and biomass data, and measured variables.

NOTE: WOD native ASCII format has been altered slightly to accomodate the changes to the standard depths for WOD13. There is a 'C' in the first byte of each cast instead of a 'B' as for World Ocean Database 2009. Provided example programs have been updated to reflect this change.

The WOD native data format can be read in a number of ways:

(1) The user can use any of a number of WOD Programs in FORTRAN and C to read the WOD/ native data format or the user can write his/her own code. The programs provided are designed as examples on how to read the WOD/ data for all types of datasets and convert data into a form useable in Matlab and ArcGIS. The sample programs prompt the user to input a data file to read casts and variables included in these casts to the screen. Note that the user needs to modify the programs to incorporate user specific needs such as single or multiple input data files, output file(s), number of cast, data output format and number of variables. The metadata codes listed within each cast are described in the code tables.

(2) The user can also use the Ocean Data View (ODV) software package to read the WOD native format and display the data.

NOTE: No prior version will read WOD data. Ocean Data View 4.5.7 has been updated to read the amended format (WOD13 and later releases).

The latest version is available from ODV website. The user will need to open a new ODV collection (or add to an existing ODV collection) and specify "World Ocean Database Variables" in the "Definition of Collection Variables" menu. The detailed instructions are available from WOD tutorial (pdf, 0.1 MB). Note that ODV will not be able to read surface only data; originator's quality flags; or plankton biomass and taxonomic data in the OSD file.

Reading WOD comma separated value (".csv") format:
The WOD ".csv" output files are space and comma-separated ASCII values. The ".csv" files can be imported into any software that allows to read "csv" data format such as Microsoft Excel. Please see the WOD "csv" data format description.