Documentation

This page contains the documentation for the CRU TS 2.0 data-set, and comprises:

Data
The CRU TS 2.0 data-set is now available online http://www.cru.uea.ac.uk/cru/data/hrg/cru_ts_2.02 (see _README.txt and introduction.pdf)

Full range of data-sets
If you have arrived at this page from a different website (without the red frame), you may be interested in the wider range of high-resolution climate grids available here. There is a table detailing the full range of data-sets. For example, there are 16 GCM-based scenarios for the 21st century on the same 0.5 degree grid (TYN SC 2.0).


Updates

4th August 2003
The reference for this data-set has been updated to: Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme,M., New, M., 2003: A comprehensive set of high-resolution grids of monthly climate for Europe and the globe: the observed record (1901-2000) and 16 scenarios (2001-2100). Journal of Climate: submitted.

13th May 2003
An elevations file for the 0.5 degree grid used here is now available. This file also implicitly describes the land-sea mask, since only land boxes are given elevations. The file format is the same as that of the data files.

9th May 2003
The country-by-country summaries of recent climate have been updated to 2000, based on these grids. See the TYN CY 1.1 data-set.

2nd May 2003
A new software page gives users the opportunity to share software for manipulating these climate grids, and reinvent the wheel less frequently!

1st May 2003
The issue of using CRU TS 2.0 for time-series analysis has been addressed more explicitly and fully. A separate page discusses time-series analysis, and additional station files have been released that record the number of stations within range of a grid-box.

25th February 2003
Download procedure eased by providing an alternative set of files for each variable. Rather than just a single file for each variable, each variable is also now broken down into 10-year periods.

4th February 2003
Data-set publicly released, as version 2.02.


Introduction
The CRU TS 2.0 data-set comprises 1200 monthly grids of observed climate, for the period 1901-2000, and covering the global land surface at 0.5 degree resolution. There are five climatic variables available: cloud cover, DTR, precipitation, temperature, vapour pressure.

It was New et al (2000) who were responsible for the original high-resolution (0.5 degree) climate grids (CRU TS 1.0) and an update to 1998 (CRU TS 1.1). See the table for more details of those data-sets. This data-set revises and extends those data-sets. The grids have been recalculated for 1901-2000, using the same basic methodology as New et al (2000). Users should not mix these grids with CRU TS 1.0 and CRU TS 1.1, except for three exceptions:

  • wet day frequencies have not been updated;
  • frost day frequencies have not been updated;
  • cloud cover has only been updated for 1971-2000.

Guidance
The primary purpose for which this data-set was constructed was to provide environmental modellers with some of the inputs they require to run their models. This purpose governed the choices that were made during the construction of the data-set. The methodology we used affects how the data-set should be used. The issues involved in using CRU TS 2.0 for time-series analysis are addressed more explicitly and fully. We recommend that all users who intend to examine climate change using this data-set should consider the issues carefully before beginning their work.

The companion data-set TYN SC 2.0 may be used to extend the period available from 2000 to 2100, through 16 climate change scenarios.


Data Structure
At present, the data-set is only available in the form of large ASCII files, compressed to a total of 0.55 GB. They are designed for use on a Unix system, not in Excel! You will need the file format details. There is also a software page. Each variable is supplied separately. The data for each variable may be downloaded as a single file, or in 10-year files. The table below gives compressed sizes of the whole-period files (in MB, not KB!). The 10-year files are approximately a tenth of these sizes. When uncompressed, the 100-year files are 412.5 MB, and the 10-year files are 42.4 MB.

variable single file (.Z)
cloud cover 54.3
DTR 91.6
precipitation 140.2
temperature 119.9
vapour pressure 90.4

Additional station files record the number of stations within range of a grid-box. These files have been released to help with any time-series analysis.

An elevations file for the 0.5 degree grid used here is available. This file also implicitly describes the land-sea mask, since only land boxes are given elevations. The file format is the same as that of the data files.


Ownership
The creator of this data set (Dr. T. D. Mitchell) retains full ownership rights over it. The data set may be freely used for non-commerical scientific and educational purposes, provided it is described as CRU TS 2.0 and attributed to:

Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme,M., New, M., 2003: A comprehensive set of high-resolution grids of monthly climate for Europe and the globe: the observed record (1901-2000) and 16 scenarios (2001-2100). Journal of Climate: submitted.


Disclaimer
The author of this data-set cannot bear any responsibility for the consequences of using it, which are entirely the responsibility of the user. It is inevitable that a data-set of this size will contain some errors and inconsistencies. However, these have been kept to a minimum and when they are identified they are corrected when resources permit. Updates to this data-set will be notified on this web page and by email to registered users.


Further Information

  • A brief introduction to the methods used in constructing the data-set is available in the release document.
  • A set of plots of example time-series is also available.
  • See the FAQ.
  • GISS (in America) have spent some time constructing products (graphs, tables, maps) from the CRU TS 2.0 precipitation data. These are publicly available from their website.
  • If you have arrived at this page from a different website (without the red frame), you may be interested in the wider range of high-resolution climate grids available here. There is a table detailing the full range of data-sets.