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Data formats

A description of the data formats

The data formats used for the UKCP09 gridded land surface climate observations data are described below.

Format of the 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.

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 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.

Format of the 25 km grid text files

The 25 x 25 km grid files contain 1961-1990 baseline averages for the grid boxes of the HadRM3 regional climate model. This model uses a rotated-pole grid to define the grid boxes, i.e. a latitude-longitude grid in which the North Pole has been rotated away from its real-world position. A description of the HadRM3 rotated-pole grid is available online.

To find the row and column numbers of a grid box in a specific part of the UK, please refer to Q19 in the list of FAQs. A map showing the outlines of all the 25 km grid boxes is available online.

The 25 km grid files are available in two formats.

Text files

These are similar in format to the 5 km grid text files. A matrix of values covering the whole of the UK is provided in one file for each month, season, or the year as a whole. Each value represents an estimate of the average for a HadRM3 model grid box.

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

  • The number of columns (39)
  • The number of rows (52)
  • A dummy value for the longitude of the south-west corner of the most south-westerly grid cell (-0.50)
  • A dummy value for the latitude of the south-west corner of the most south-westerly grid cell (-0.50)
  • A dummy value for the grid cell size (1.00)
  • The value which indicates no data (9999.00, this indicates that the grid square is outside the scope of the climate data, which is UK land areas)

The matrix of values follows, arranged according to 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). 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. However, due to the use of a rotated-pole grid, dummy values have been used for the location of the south-west corner and the grid cell size. Users of ESRI software can import the files without modification, but it may not be possible to combine the data with other information that uses a different grid system.

netCDF files

The 25 km grids are also available in CF-netCDF format. This is a commonly used binary format for climate and forecast data sets. Further information can found via the following links.

The Met Office is not responsible for the content of external internet sites.

Format of time series text files

For daily data, the first two rows contain the British National Grid easting and northing of the grid point (i.e. the centre point of a 5 x 5 km grid cell). Subsequent rows contain the date in the first column, followed by values of the climate variable for each grid square. Columns are separated by commas. The files are provided in 50 x 50 km blocks (170 files to cover the UK) so that the full time series can be provided in a single file.

easting,    352500, 357500, 362500,...

northing,   302500, 302500, 302500,...

1960/01/01, value,  value,  value,...

1960/01/02, value,  value,  value,...

1960/01/03, value,  value,  value,...

etc.

For monthly and annual data, the first two columns give the British National Grid easting and northing of the grid point. Subsequent columns contain values of the climate variable for a monthly or annual time series. Columns are separated by commas, and headings are given in the first row. The monthly files are provided in 20-year blocks.

easting, northing, Jan-1980, Feb-1980, Mar-1980,…

352500,    302500,    value,    value,    value,...
357500,    302500,    value,    value,    value,...
362500,    302500,    value,    value,    value,...
etc.

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

Format of regional values text files

Each text file contains values of the 1961-1990 baseline average for 14 administrative regions and 23 river basins. For monthly variables there are 12 columns of data, one for each month. Files for annual variables will only contain one column of data, i.e. the annual average.

Please use the following links to see maps of the administrative regions and the river basins.

The format of a regional values text file for a monthly variable is shown in the following example.

ADMINISTRATIVE REGION          Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec
East Midlands                 5.83   6.09   8.86  11.51  15.29  18.50  20.38  20.19  17.67  13.82   8.94   6.68
East of England               6.15   6.52   9.32  12.00  15.89   ....    etc
East Scotland                 ....   ....   ....
London                        ....
North East England            etc
North Scotland                
North West England            
Northern Ireland              
South East England            
South West England            
Wales                         
West Midlands                 
West Scotland                 
Yorkshire & The Humber        

RIVER BASIN                    Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec
Anglian                       6.08   6.44   9.25  11.90  15.75  18.99  20.95  20.93  18.41  14.48   9.41   6.99
Argyll                        5.22   5.21   6.64   9.33  12.52   ....    etc
Clyde                         ....   ....   ....
Dee                           ....
Forth                         etc
Humber                        
Neagh Bann                    
North East Scotland           
North Eastern Ireland         
North Highland                
North West England            
North Western Ireland         
Northumbria                   
Orkney and Shetland           
Severn                        
Solway                        
South East England            
South West England            
Tay                           
Thames                        
Tweed                         
West Highland                 
Western Wales

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