[[TOC]]

Climatic Research Unit (CRU) time-series datasets are month-by-month variations in climate over the last century or so. These are calculated on high-resolution (0.5x0.5 degree) grids, which are based on an archive of monthly mean temperatures provided by more than 4000 weather stations distributed around the world. They allow variations in climate to be studied, and include variables such as cloud cover, diurnal temperature range, frost day frequency, precipitation, daily mean temperature, monthly average daily maximum temperature, vapour pressure and wet day frequency.

The last version described (February 2014) is CRU TS 3.21, produced by the British Atmospheric Data Centre (BADC) in July 2013. The default input.conf uses version 3.10 for TMP and CLD input.

CRU TS 3.21
This is the current version and, according to CRU, supercedes all previous versions. The data span from 1901 to 2012. The following variables have been prepared as input for LPJmL: cloud cover (CLD), precipitation (PRE), monthly average daily minimum temperature (TMN), daily mean temperature (TMP), monthly average daily maximum temperature (TMX), wet day frequency (WET). The files (CLM with the new header) are found in /iplex/01/2011/isimip-lpj/input_CLM2. This directory also includes the release notes and an advisory regarding known errors of the precipitation and wet day data in Northeastern Africa.

CRU TS 3.10
The data were produced by BADC in 2011 and span from 1901 to 2009. The following variables have been prepared as input for LPJmL: cloud cover (CLD), diurnal temperature range (DTR), precipitation (PRE), monthly average daily minimum temperature (TMN), daily mean temperature (TMP), monthly average daily maximum temperature (TMX), wet day frequency (WET). The files (CLM with the new header) are found in /iplex/01/2012/open/input_VERSION2. CLM files with the old header are found in /data/biosx/LPJ/cru09.
In July 2012, systematic errors were discovered in the CRU TS 3.10 process by BADC, effecting PRE and WET. The files were retracted, and a corrected precipitation run (called CRU TS 3.10.01) was released. The default input.conf uses GPCC precipitation and wet day frequency.

CRU TS 3.00
The data were produced by CRU in 2007 and span from 1901 to 2006. The following variables have been prepared as input for LPJmL: cloud cover (CLD), precipitation (PRE), monthly average daily minimum temperature (TMN), daily mean temperature (TMP), monthly average daily maximum temperature (TMX), wet day frequency (WET). The files (CLM with the new header) are found in /iplex/01/2012/open/input_VERSION2. CLM files with the old header are found in /data/biosx/LPJ/cru06 and maybe in other places. Files are just called “cld.clm”, “pre.clm” etc. with no indication of the CRU version they are based on.

Input

For CRU TS. 3.10 and later versions: Harris, I., Jones, P.D., Osborn, T.J., and Lister, D.H., 2013: Updated high-resolution grids of monthly climatic observations. Int. J. Climatol., Doi: 10.1002/joc.3711
For earlier versions: Mitchell and Jones, 2005: An improved method of constructing a database of monthly climate observations and associated high-resolution grids. Int. J. Climatology, 25, 693-712, Doi: 10.1002/joc.1181
Data at BADC: http://badc.nerc.ac.uk/data/cru/