Met Office Hadley Centre observations datasets
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HadIOD: ocean temperature and salinity in situ observations with quantified measurement errors and quality flags


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Dataset Description

HadIOD (Hadley Centre Integrated Ocean Database) is a relational database of global historical in situ ocean temperature and salinity observations. It brings together observations made by surface-only observing platforms (like ships and buoys) and observations from sub-surface ocean profiling platforms (like profiling floats and bathythermographs) and supplements these with additional metadata including quality flags, bias corrections and estimates of measurement uncertainty. The current version of HadIOD is HadIOD.

Data extracted from the database are made available from 1850 to present in CF-compliant NetCDF format files. There is a single file for each day that contains the bulk of the data and separate daily files containing additional sets of bias corrections. We update the HadIOD database with new data and create new files each month on a best endeavours basis. Updates are made with approximately a few months delay from the end of the target month (so for example the September 2019 update would be made around late November 2019). The data in the files are a subset of the data and fields in the HadIOD database. We have provided the information we expect an average user to need.

How does HadIOD compare to other Met Office Hadley Centre marine observations datasets?

HadIOD gets its quality controlled ocean profile data from EN4 and as such there are significant similarities between these datasets. The chief difference is that HadIOD also includes quality controlled data from surface-only platforms, which will be helpful in certain applications such as satellite validation or ocean analyses where observations from the sub-surface ocean and near the ocean-atmosphere interface are needed for assimilation. HadIOD also includes a more thorough treatment of observations errors and uses its own optimal ragged array data format.

HadIOD provides in situ observations only and gridded or interpolated fields are not provided. Objective analyses formed from ocean profile data are provided by EN4, gridded historical sea-surface temperatures are provided by HadSST4 and globally complete sea-ice and sea-surface temperature fields are provided by HadISST.

Further Information

For more information please start by reading the product user guide (see right).

For published information see: Atkinson, C. P., N. A. Rayner, J. J. Kennedy and S. A. Good, 2014. An Integrated Database of Ocean Temperature and Salinity Observations, Journal of Geophysical Research: Oceans, 119, 7139-7163, doi:10.1002/2014JC010053 (free access).


The current version of HadIOD is HadIOD. It was created as part of the EU-FP7 ERA-CLIM2 project with contributions from the ESA SST CCI phase II project and is currently maintained as part of C3S (European Union Copernicus Climate Change Service). HadIOD is supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra.

HadIOD is an amalgamation of various observational datasets and observational studies and as such relies on the work of many other people. Full details of the sources of data in HadIOD are given in the product user guide.

Generated using E.U. Copernicus Marine Service Information.


Please contact us if you need any assistance.

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Figure 2 of Atkinson et al. (2014). Maps showing maximum observed depths (meters) of temperature observations in HadIOD. for April 1905, 1935, 1965, 1985, 1995 and 2010. Only observations that pass quality control checks and duplicate checks are shown. For ocean profile observations (bold, colored crosses), each of which comprises a series of measurements made at multiple depths at some location and time, maximum observed depth is the depth of the deepest measurement in a profile. For surface-only observations (fine, dark-red crosses), each of which comprises a measurement made at a single (near-surface) depth at some location and time, maximum observed depth is simply the depth of the measurement. The type and coverage of temperature and salinity observations has evolved through time with changes in the observing system.

Obtaining the data

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Data are made available without charge for Non-Commercial use, please read the terms and conditions.
If you use HadIOD data we would be grateful if you could let us know for our records.

Product User Guide

A product user guide is available as a pdf. This includes more in depth material including how to work with the bias correction and uncertainty information and a description of the data format.

Citing the data

Please see the product user guide and read the terms and conditions.

Contact us

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If you cannot find the information you require on these webpages or in the product user guide, please do contact us. We are also interested in receiving feedback about the data and its usability. See below if your query is of a commercial nature or relates to the media.

Feedback Format Data

HadIOD has also been extracted into NEMO NetCDF feedback format. Basic information can be found on the feedback format pages.

Commercial and media enquiries

You can access the Met Office Customer Centre, any time of the day or night by phone, fax or e-mail. Trained staff will help you find the information or products that are right for you.
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