Met Office - HadSST2 - Uninterpolated sea-surface temperature data (1850-present)

Introduction

The Met Office Hadley Centre's sea surface temperature data set, HadSST2, replaces the Met Office Historical Sea Surface Temperature dataset (MOHSST6) and is a monthly global field of SST on a 5 deg latitude by 5 deg longitude grid from 1850 to date. The data are neither interpolated nor variance adjusted.

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 present.

HadSST2 is produced by taking in-situ measurements of SST from ships and buoys, rejecting measurements 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 deg by 5 deg 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 following paper:

Rayner, N.A., P.Brohan, D.E.Parker, C.F.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.

This data is provided by the Met Office Hadley Centre.

Map of monthly average SST anomalies (relative to 1961-1990) from HadSST2. White area represent gridboxes containing no SST data. The black crosses and dashes indicate that a pixel is, respectively, the warmest or coldest example of that calendar month in the record. (courtesy of the Met Office)

Restricted Data Access

The Met Office wish to monitor the use of this data and require an acknowledgement of the data source if they are used in any publication. The online application for access to the Met Office SST data includes the Met Office Agreement to be electronically accepted.Please note that the Met Office data sets are available for bona fide academic research only (sorry no undergraduates), on a per person per project basis (i.e. all members on a same project who will be using the data must individually apply for access to the data). If you wish to access the Met Office data for commercial or personal purposes, please contact the Met Office directly.

Your application for accessing the HadSST2 data will be processed within a day of receipt. Provided your application is complete and fully meets the Met Office conditions, a web account will be activated to allow you access to the HadSST2 directories via your login account from the BADC WWW Browse Archive pages.

Please read the 00README file available under /badc/ukmo-hadsst2/ directory to to guide you through the tree structure and the data directory.

Data availability and File Format

The SST anomaly data are available as a set of compressed plain text files (HadSST2_SST_1850_onwards).
The 12 fields of actual climatological SSTs corresponding to each calendar month are available in a plain text file from 1850 to present (HadSST2_climatology_5x5_1961_1990.txt)
The numbers of observations used to calculate the average are available in a plain text file (HadSST2_nobs_1850on.txt).
Estimates on the measurement and sampling errors on the SST data are available as a set of compressed plain text files (HadSST2_m_and_s_errors_1850on.txt).
The following two datasets are bias-adjusted using bias adjustments which represent the 97.5 percent and 2.5 percent confidence levels of the estimated errors on the adjustments. They are available as a set of compressed plain text files. (HadSST2_97.5_pct_bias_1850on.txt and HadSST2_2.5_pct_bias_1850on.txt).

The data held at the BADC, are stored in a simple ASCII format (plain text and "human" readable). Information relative to the file format can be found in the documentation as provided by the Met Office Hadley Centre.

Links to Further Information

The Met Office Hadley Centre for Climate Change observational datasets site - www.hadobs.org.

HadSST2 Diagnostics including maps of monthly data (most recent month), and annual and monthly time series (global and hemispheric) are available from the Hadley Centre.

A list of references is provided.

Who to Contact

If you have queries about these pages or about obtaining the Met Office GISST data from the BADC then you should contact BADC Support. Your query should be answered within one working day. When follow-up work is required, the BADC support will carry out the work as quickly and efficiently as possible, and in any case, the user will be kept informed of progress.

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