Met Office Hadley Centre observations datasets
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Hadley Centre Sea Level Pressure dataset (HadSLP1)

The Met Office Hadley Centre's mean sea level pressure (MSLP) data set, HadSLP1, replaces the Global Mean Sea Level Pressure (GMSLP) data sets, and is a unique combination of monthly globally-complete fields of land and sea pressure observations a 5 degree latitude-longitude grid from 1871 to 1998. It has subsequently been superseded by HadSLP2 that users should consider in preference. HadSLP1 is maintained solely for comparison purposes with our newer product and must not be used in isolation.

Brief description of the data

The advantages of HadSLP1 over GMSLP2 are an improved land station data base, new interpolation scheme and the incorporation of local detail while safeguarding against random errors. Like GMSLP2, HadSLP1 was developed by Tracy Basnett and David Parker, in collaboration with R.J. Allan (previously at CSIRO and now at the Met Office) and M.J. Salinger (NIWA)

Marine observations were taken from the Met Office Marine Data Bank (MDB) and from the Comprehensive Ocean-Atmosphere Data Set (COADS) (now ICOADS). The MDB data were given priority in the blend, which is described in Basnett and Parker (1997). Land observations are a combination of data obtained from CSIRO (Australia), NIWA (New Zealand), CRU (University of East Anglia), GHCN, and operationally-received "CLIMAT" messages. The latter were used mainly for updating station series and for the Arctic.


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When using the data set in a paper, HadSLP1 should be cited as an update of GMSLP2. The correct citation to use for GMSLP2 is:

Basnett, T. and Parker, D. (1997)  'Development of the Global Mean Sea Level Pressure Data Set GMSLP2', Climate Research Technical Note, 79, Hadley Centre, Met Office, FitzRoy Rd, Exeter, Devon, EX1 3PB, UK 

Other information

Please note that between June-November 2004 an incorrect version of HadSLP1.0_1871-1998.asc.gz (the observations only version of HadSLP1) was available to download. This has now been replaced with the correct file. We are very sorry for any problems this may have caused.

Dataset produced in collaboration with:

Met Office Hadley Centre ICOADS