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UKCP09: Format of 5 km grid text files

Grid text files provide a matrix of values covering the whole of the UK, in one file for each day, month or year. Each value represents an estimate for the centre point of a 5 x 5 km grid cell.

Gridded data diagram

These grid cells are identified using the Ordnance Survey National Grid, extended to cover Northern Ireland. The area covered is shown in this map, with climate variable values for all land areas coloured green and -9999 elsewhere.

To identify the grid cells that cover a particular location, please use this map or refer to Q19 in the list of FAQs.

The data are preceded by six header rows constructed as follows.

  • The number of columns (180)
  • The number of rows (290)
  • The six-figure (1-metre precision) British National Grid easting of the south-west corner of the most south-westerly grid cell (-200000)
  • The six-figure (1-metre precision) British National Grid northing of the south-west corner of the most south-westerly grid cell (-200000)
  • The grid cell size, in metres (5000)
  • The value which indicates no data (-9999, this usually indicates that the grid square is outside the scope of the grid, which is UK land areas).

The matrix of values follows, arranged to reflect the natural geography of the UK when presented on screen or paper, i.e. the values in each row run from west to east (reading from left to right) and the rows are ordered from north to south (reading from top to bottom), in steps equal to the grid cell size. The data are presented as space-delimited values.

Note: The format of the grid text files is the same as that used by ESRI GIS software (e.g. ArcView) to import/export gridded data as plain text. Users of such software can import the files without modification.

Related internet links

Department for Environment, Food and Rural Affairs (Defra)

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