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ISLSCP II Climate Research Unit CRU05 Monthly Climate Data
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Revision date: May 31, 2011

Summary:

This data set contains a mean monthly climatology for several climate variables averaged over the period from 1961 to 1990, and constructed from a data set of station 1961-1990 climatological normals, numbering between 19,800 (precipitation) and 3,615 (windspeed; see New et al, 1999 for details). The data were created by the Climatic Research Unit (CRU) at the University of East Anglia. CRU05 identifies these as version 5 data. The station data were interpolated as a function of latitude, longitude and elevation using thin-plate splines. The data comprise a suite of climate elements: precipitation, mean, maximum, and minimum  temperature, frost frequency, diurnal temperature range, radiation, wet-day frequency, vapor pressure, wind, and cloud cover. There are 23 files in this data set provided at 0.5 and 1.0 degree spatial resolutions. 

Additional Documentation:

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named  1_cru_monthly_mean_doc.pdf.

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

Related Data Sets:

Data Citation:

Cite this data set as follows:

New, M., P.D. Jones, and M. Hulme. 2011. ISLSCP II Climate Research Unit CRU05 Monthly Climate Data. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection.  Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/1015

File Information:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the Near-Surface Meteorology category.

Data Set Spatial Extent: Global gridded

Westernmost Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90 N

Southernmost Latitude: -90 S

Projection: Geographic

Data Set Spatial Resolution:  1.0 degree  and 0.5 degree in both latitude and longitude

Data Set Temporal Extent: 1986 through 1995

Data File Format:

All of the data files (*.zip) are in standard ESRI ArcGIS ArcInfo ASCII grid format.  The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The files in this data set are provided at 1.0 degree and 0.5 degree spatial resolutions and contain the following numbers of columns and rows:

One degree (1d): 360 columns by 180 rows
Half degree (hd): 720 columns by 360 rows

NOTE: The 1.0 x 1.0 degree product is for browse use only. These data files are averaged from the original 0.5 x 0.5 degree pixels. Thus the data values at specific pixels are not exact. Use this data with caution and refer to the original half-degree data files for specific information.

File Naming Conventions:

cru5_variable_Xd_1961-90.zip: 22 files where variable is the climate variable name (see table below), Xd is 1d or hd for 1.0 degree or 0.5 degrees spatial resolutions, and 1961-90 identifies the data as monthly averages for the entire period. Each zip file, when expanded, contains 12 ASCII files (.asc), one file for each of the 12 months.

The 0.5 degree (hd) .zip files also contain 12 "differences" (.dif) files. These are ASCII tables of "differences", points that didn't match the ISLSCP Initiative II Land/Water mask, and were removed from or added to the ASCII map files.

cru5_mean_hd_changemap.asc:  gridded ASCII maps showing the results of applying the 0.5 degree ISLSCP II land/water mask for the original CRU data: all points added ("1"), all points unchanged ("0"), and all points removed ("-1"). These files are only available for the original 0.5 degree data set because the 1.0 degree version was created by the ISLSCP II staff by averaging the 0.5 degree data

Climate Variables

Abbreviation Variable
cloud_covrCloud cover
diurnl_tmp Diurnal temperature range
frost_freq Ground frost frequency
precip Precipitation
radiation Radiation
temp_maxMaximum temperature
temp_mean Mean temperature
temp_minMinimum temperature
vapor_presVapor pressure
wetday_ frq Wet day frequency
windWind

The 23 data files include 22 compressed (*.zip) files and 1 ASCII changemap file, named as follows:

* cru5_cloud_covr_1d_1961-90.zip

* cru5_cloud_covr_hd_1961-90.zip

* cru5_diurnal_tmp_1d_1961-90.zip

* cru5_diurnal_tmp_hd_1961-90.zip

* cru5_frost_freq_1d_1961-90.zip

* cru5_frost_freq_hd_1961-90.zip

* cru5_precip_1d_1961-90.zip

* cru5_precip_hd_1961-90.zip

* cru5_radiation_1d_1961-90.zip

* cru5_radiation_hd_1961-90.zip

* cru5_temp_max_1d_1961-90.zip

* cru5_temp_max_hd_1961-90.zip

* cru5_temp_mean_1d_1961-90.zip

* cru5_temp_mean_hd_1961-90.zip

* cru5_temp_min_1d_1961-90.zip

* cru5_temp_min_hd_1961-90.zip

* cru5_vapor_pres_1d_1961-90.zip

* cru5_vapor_pres_hd_1961-90.zip

* cru5_wetday_frq_1d_1961-90.zip

* cru5_wetday_frq_hd_1961-90.zip

* cru5_wind_1d_1961-90.zip

* cru5_wind_hd_1961-90.zip

Please refer to 1_cru_monthly_mean_doc.pdf and 0_cru_mean_readme.txt  for a more complete description of the data files and naming conventions.

References:

New, M., M. Hulme and P. Jones (1999). "Representing twentieth-century space-time climate variability. Part I: Development of a 1961-90 mean monthly terrestrial climatology". Journal of Climate 12: 829-856. doi:10.1175/1520-0442(1999)012<0829:RTCSTC>2.0.CO;2