Global Seawater Oxygen-18 Database

This database is a collection of over 26,000 seawater O-18 values made since about 1950. We hope that other researchers can benefit from the not-inconsiderable pain it took to collect, verify and put together all these different sources.

This is a amalgamation of independent efforts by Gavin Schmidt, Grant Bigg and Eelco Rohling which combines our separately evolved interests. Partial versions of this databases appeared in Schmidt (1999) and Bigg and Rohling (2000). These publications can (should!) be referenced, but references to the whole database (currently version 1.22) should include the web address as follows:

Schmidt, G.A., G. R. Bigg and E. J. Rohling. 1999. "Global Seawater Oxygen-18 Database - v1.22" https://data.giss.nasa.gov/o18data/

Since this data comes from different laboratories, different standards have been used and it is not always possible to make everything consistent. If you find that strange phenomena occur across different data sets, please don't blame us! Make sure to read the notes that go along with each reference, and try and go back to the original articles (where possible) for clarification. If there are still unresolved issues, please let us know and we will try to investigate. If you know of more pertinent data that could usefully be included here, please let us know and it will happen. Nominally all delta values are with respect to V-SMOW. Published values that used an older standard (original SMOW or PDB) have been corrected (and there is a note in the data reflecting this).

Note added 27 Dec 2006: Temperature measurements can be in-situ or potential temperature (theta). If this matters for you, please check with the original reference.

Map of observation locations of surface ocean O-18 ratios dataset

Database Capabilities

You can search the database to find data that you are particularly interested in. The fields include, δ18O, salinity, temperature, depth, latitude, longitude, reference, deuterium, year and month. For example, you might be interested in all samples that have an associated salinity, between the depths of 1000 and 2000 meters in the Atlantic Ocean. This is possible by choosing the limits for depth (1000-2000m), salinity (0-40 say) and longitude. You can also choose what fields you want output (i.e., just the salinity and δ18O, or the whole data entry) by checking off the check boxes for those fields you don't want.

You can download this data (or even the whole database) directly, but we do provide graphical output also. You can plot latitude/longitude positions of the matching data and also plot columns of data against each other in a scatter plot.

We have made some attempts to calibrate the data so that comparisons can be more easily made. Our standard is the excellent set of measurements from GEOSECS made by Harmon Craig. These are the nearest data set we have to being global and homogeneous. Where possible, we have calibrated other datasets so that deep water properties (which should be stable over the time periods considered here) are constant across data sets. Where this has been done a note explains the correction. In this way, we hope to correct for changes in standards, different techniques, different mass spectrometers, and hopefully other systematic errors. Since all changes are flagged, you are at liberty to ignore our "corrections".

Since we realize that many researchers are interested in the integrated surface ocean (top 50m) δ18O field, we have interpolated all the surface data onto a 4ox 5o grid. Please note that we use a relatively wide circle of influence (up to 5 great circle degrees) and so this might not be optimal in smaller regions where there is a lot of data, or where there is significant structure in the top 50m. Feel free to construct other estimates!

Global map of surface ocean O-18 ratios

A ascii text version of the data used to make this figure is also available. Be aware that the data is very sparse in many areas, and gridded data sets can offer the illusion of completeness.

Start database search

Gridded Data

We have made a preliminary attempt to create a gridded data set from the values available in the database. This dataset is described in LeGrande and Schmidt 2006 and uses regional δ 18O - salinity relationships and PO4* to define water mass boundaries. Further explanation and the data are provided on a separate page. A plot of version 1.1 is shown below. The difference between this and the original version is here.

Unpublished Data

The policy we have adopted here is to allow public access to data that has been published (or alluded to) in the open literature. Some unpublished data are included with the express permission of the originator (referenced as a personal communication). At some point, we will include partial descriptions of as-yet-unavailable data to give a clearer picture of what data actually exists.

What's New

Updates to the database are listed on a separate page.

Acknowledgments

Some institutions and individual researches were kind enough to let us have unpublished data, for which we are thankful. In particular Karen Heywood, Gerald Ganssen, Jean-Claude Duplessy, Anne Juillet-Leclerc, Howie Spero and Rick Fairbanks have all been very generous. Gilles Delaygue, Mike Meredith, Duane Thresher, Martin Wadley have also been especially helpful. Samar Khatiwala, Lee Cooper, Peter Strain and Peter Schlosser were kind enough to give us their own collected data sets. Finally, we thank the researchers who worked hard to collect this data - often in very difficult circumstances. Funding for GAS for work on seawater oxygen-18 observations and modelling was provided by NSF Earth System History program (ATM-9905038). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

References for all the data included are also available.

NB: While you are perfectly at liberty to download the whole database for your own research, please make a note of the version and note that corrections, additions, and re-calibrations are all on-going. Much of the data was typed in by hand, and so many errors probably remain.

The whole database can be downloaded from this link (3MB). The format is fixed width:

%7.2f%6.2f%2d%4d%5d%6.2f%6.2f%6.2f%6.1f%15s%60s

with longitude, latitude, month, year, depth (m), temperature (C), salinity (psu), δ18O, δD, notes, reference.

Contacts

If you would like to comment, correct, notify, complain, harangue, compliment, or otherwise communicate with us, feel free. We can be reached most effectively by email (replace -at- by @ in the addresses below).