Met Office Hadley Centre observations datasets
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Hadley Centre SST data set (HadSST2)

We corrected a minor bug in the error ranges provided for HadSST2 (the best estimate data are unchanged). If you have downloaded HadSST2 before November 20th 2007 please see this page.

The Met Office Hadley Centre's sea surface temperature data set, HadSST2 is a monthly global field of SST on a 5° latitude by 5° longitude grid from 1850 to date. The data are neither interpolated nor variance adjusted.

Fields for the latest available month (see for example the image below which shows sea-surface temperature anomalies for the most recent available month. A plus sign in any grid box indicates that the temperature anomaly in that grid box this month is the highest since the dataset starts in January 1850. Similarly a minus sign signals the lowest anomaly since 1850. ) are added to the data set on or around the 10th of the next month. In the picture white areas represent land and areas where there no SST observations were made.

Brief description of the data

The SST data are taken from the International Comprehensive Ocean-Atmosphere Data Set, ICOADS, from 1850 to 1997 and from the NCEP-GTS from 1998 to the present. HadSST2 is produced by taking in-situ measurements of SST from ships and buoys, rejecting measurements which which fail quality checks, converting the measurements to anomalies by subtracting climatological values from the measurements, and calculating a robust average of the resulting anomalies on a 5° by 5° degree monthly grid. After gridding the anomalies, bias corrections are applied to remove spurious trends caused by changes in SST measuring practices before 1942. The uncertainties due to under-sampling have been calculated for the gridded monthly data as have the uncertainties on the bias corrections following the procedures described in the paper.

For a detailed description of the dataset and its production process, see the paper cited in the references section. We recommended you read this before using the data.

Sea surface temperature anomalies with respect to 1961-90 from HadSST2

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When using the data set in a paper, the following is the correct citation to use:

Rayner, N.A., P.Brohan, D.E.Parker, C.K.Folland, J.J.Kennedy, M.Vanicek, T.Ansell and S.F.B.Tett 2006: Improved analyses of changes and uncertainties in sea surface temperature measured in situ since the mid-nineteenth century: the HadSST2 data set.  Journal of Climate. 19(3) pp. 446-469 (pdf ~17 Mb)

Other information

Various diagnostics are produced from the monthly gridded fields. These include images of monthly anomaly patterns, and global and hemispheric time series.

Frequently Asked Questions.

Dataset produced in collaboration with:

Met Office ICOADS