% Berkeley Earth Surface Temperature
% 
% README file for High-Resolution Gridded Data
% 
% PRELIMINARY DATA - SUBJECT TO CHANGE WITHOUT NOTICE - NOT YET PEER REVIEWED
%
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% 
% This file is based on the new high-resolution Berkeley Earth global temperature
% data set.  It expands upon the previous Berkeley Earth temperature data set by
% including predictive structures based on historical weather patterns and 
% increasing the underlying resolution to 0.25° x 0.25° latitude-longitude.
% Files based on this new data set are being provided as part of an early preview
% to aid in the identification of any remaining bugs or errors.  While, we 
% believe the current dataset to be accurate and useful, it is still in 
% development and substantial revisions remain possible if significant issues
% are identified.
% 
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% 
% This file describes the format used by the Berkeley Earth Surface 
% Temperature project for high resolution gridded data fields.  These fields 
% contain reconstructed monthly temperature anomaly values generated by the
% Berkeley Earth project based on our method of climate analysis.
%
% At present all gridded data is provided via the NetCDF format (version
% 4).  NetCDF, short for Network Common Data Form, is a standardized data
% format commonly used for the exchange of large data sets, including
% weather data.  Tools for reading NetCDF are available in most major
% programming languages, including Matlab, R, C++, and others.
%
% File Naming Convention
%
% Gridded data files have names with the format:
%
%    <region>_<variable name>_Gridded_<resolution>.nc
%
%       OR
%
%    <region>_<variable name>_Gridded_<resolution>_<decade>.nc
%
% The <region> indicates the temperature data set from which 
% the analysis was constructed.
%
% The <variable name> is an indicator of the kind of data in the file.
% Currently the only valid option is TAVG indicating fields for
% average temperature.  Future releases will include TMAX and TMIN for
% maximum temperature and minimum temperature respectively.
% 
% The <resolution> indicates the scale of gridded data provided.
% Currently, the supported choices are 0p25, 1, and 5, indicating 0.25x0.25,
% 1x1, and 5x5 degree lat-long grids respectively.
%
% File Contents
%
% The following variables are presently included in the gridded data set:
%
%    latitude
%    longitude
%    time
%    temperature
%    land_mask
%    climatology
%
% latitude: A list of latitude values indicating grid box centers.  It 
%   lists the centers for a single column.  Values are in degrees,
%   with positive values used for the Northern Hemisphere.
%
% longitude: A list of longitude values indicating grid box centers.  It 
%   lists the centers for a single row.  Values are in degrees,
%   with positive values used for the Eastern Hemisphere.
%
% time: A list of times at which data is reported.  Data format is decimal
%   with year and fraction of year reported, with each value corresponding
%   to the midpoint of the respective month.  For example, 1981.125
%   indicates February 1981.  
%
% temperature: A surface air temperature anomaly field.  The dimensions
%   are latitude x longitude x time.  Each element measures the local 
%   temperature anomaly, in degrees C, for the corresponding location 
%   and time.  Missing values are reported as NaN.  A value is reported 
%   as missing if the coverage diagnostic indicates that the locally
%   available data provides less than a 20% constraint on the anomaly.
%
% land_mask: For each grid cell, the fraction of the cell which corresponds
%   to land (as opposed to ocean or other large water bodies).  
%
% climatology: For each grid cell, an estimate of the true surface
%   temperature for each month during the period January 1951 to December
%   1980 reported in degrees C.  The dimensions are 
%   latitude x longitude x month, where month has length 12 and corresponds 
%   to January through December respectively.  Hence the first month is an 
%   estimated average for all Januarys from 1951 to 1980, the second month 
%   is for all Februarys, etc.
%
% The gridded data files do not currently contain uncertainty information.
%   Gridded uncertainty files will be provided separately in the neare future.