% Berkeley Earth % % README file for Daily Gridded Data % % This file describes the format used by the Berkeley Earth project % for gridded data fields. These fields contain reconstructed % daily temperature anomaly values generated by the Berkeley Earth % project based on our method of climate analysis. % % The current version of the daily dataset is an experimental product, % and may be subject to substantial revision without notice. It has % yet been described in the peer reviewed literature. We are releasing % this dataset as is, in order to attract attention and get feedback % from potential users of this dataset. % % 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 % % Daily gridded data files have names with the format: % % __Daily_.nc % or % __Daily__.nc % % The indicates the temperature data set from which % the analysis was constructed. Currently, the only valid value for this % is "Complete", indicating that all data from the Berkeley Earth data set % was used. In the future, GHCN and other alternative data sets may also % be added. % % The is an indicator of the kind of data in the file. % Currently, valid options are TAVG, TMAX, and TMIN indicating fields for % average temperature, maximum temperature, and minimum temperature, % respectively. % % The indicates the type of gridded data provided. % Currently, the supported choices are "EqualArea" and "LatLong1". % "EqualArea", indicates a 15,984 element equal area grid which is the % format commonly used by the Berkeley Earth project to represent the globe % for many applications. "LatLong1" is a resampled field using a % 1 degree-by-1 degree latitude-longitude grid covering the Earth. This % format is likely to be more useful for many applications. % % The specifier, if present, indicates that the data file contains % only the associated decade worth of daily data. For example, if a file % specifies 1990 as the last element then it contains data from Jan 1, 1990 to % December 31, 1999 inclusive. We have broken the files into decadal segments % in order to help users better manage the very large size of the aggregate data. % A decadal block in the lat-long format can be as large as 450 MB within a % compressed NetCDF and expand to about 900 MB in memory. % % File Contents % % The following variables are presently included in the gridded data set: % % latitude % longitude % date_number % year % month % day % day_of_year % land_mask % temperature % climatology % % latitude: A list of latitude values indicating grid box centers. For % the "EqualArea" product it lists every grid box, and for the "LatLong1" % product 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. For % the "EqualArea" product it lists every grid box, and for the "LatLong1" % product it lists the centers for a single row. Values are in degrees, % with positive values used for the Eastern Hemisphere. % % date_number: A list of dates at which data is reported. Data format is decimal % with year plus fraction of year reported, with each value corresponding % to the midpoint of the respective day. For example, 2000.0123 % indicates January 5, 2000. % % year: A list of years at which data is reported. Combine with "month" and % "day" to form a full date. % % month: A list of months at which data is reported. Combine with "year" and % "day" to form a full date. % % day: A list of days at which data is reported. Combine with "year" and % "month" to form a full date. % % day_of_year: A list of the day of year (1-365) at which data is reported. % This can be used with the "climatology" to select the appropriate climatology % day to use with each day of temperature anomalies. During leap years, % there will be one duplicated day_of_year value. % % temperature: A surface air temperature anomaly field. For "LatLong1" % case, the dimension are latitude x longitude x date. For the % "EqualArea" case, the dimensions are number of grid cells x date. Each % element measures the local temperature anomaly, in degrees C, for the % corresponding location and date. Missing values are reported as NaN. % A value is reported as missing if the grid cell is less than 5% land or % 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 day of year (1-365) during the period January 1951 % to December 1980 reported in degrees C. For "LatLong1", the dimensions are % latitude x longitude x day_of_year, where day_of_year has length 365. % For the "EqualArea" case, the dimensions are grid cell number x day_of_year. % % % % The gridded data files do not currently contain uncertainty information.