**Documentation**

This page contains the documentation for the TYN CY 1.1 data-set, and comprises:

- Updates
- Introduction
- Changes compared to the previous version (TYN CY 1.0)
- Climatic variables included
- Guidance on how to use the data-set
- Data Structure
- Ownership
- Disclaimer
- Data Processing
- Original Data

**Data**

The TYN CY 1.1 data-set itself may be accessed in two ways:

browse by country,

browse by climate
variable.

There are also examples of published academic work that use the country climate data-sets. Other relevant data-sets, including other country data-sets, may be found under Data.

**9th May 2003**

Additional information on time-series analysis has been added. This data-set should only be used for time-series analysis (e.g. trends or regression) with the greatest of care. This data-set is based on the CRU TS 2.0 grids, and the discussion of the limitations on the use of that data-set is relevant here.

**8th May 2003**

This version is an update to TYN CY 1.0. Note the changes.

Introduction

The data set
described here provides a summary of the climate of the 20th century for
289 countries and territories.

- The primary product
is the
**average climate**in the recent past (1961-1990), which is supplied for nine climate variables. - A secondary product
is the set of
**year-by-year variations**over the 20th century (1901-2000), which is supplied for seven climate variables.

- each calendar month (January-December),
- each climatic season (March-May, June-August, September-November, December-February),
- the calendar year (January-December).

The previous version of this data-set (TYN CY 1.0) was based on the CRU TS 1.0 and CRU TS 1.1 grids. This update is based on the CRU TS 2.0 grids. (For information on the grids, see the Table.) For full details of the changes made in the grids, see the CRU TS 2.0 documentation.

The relevant changes for this country data-set are as follows:

- The time-series for all available climate variables have been regridded and
**extended to 2000**. The new observed time-series information entirely replaces the old information. See the individual variable files for each country in the country table. - The mean climatology (1961-90) has not been altered in the grids; the mean climatology is still that of CRU CL 1.0 (see the Table). The climatic summary for each individual country is available through the country table. The consolidated file (all countries) for each variable is available through the variable table.
- In addition to the 30-year mean from 1961-90, for five variables we now also present the
**interannual standard deviation**from that 30-year period. Please note that these data may include influences from the changes over time in the station networks contributing to the underlying grids (see discussion). Therefore, particularly for smaller countries and data-sparse regions, the 'standard deviation' presented here may not be entirely climatic, but also a function of the number of observations. The consolidated file (all countries) for each variable is available through the variable table.

Guidance

This data
set is intended for use in trans-boundary research, where it is necessary
to average climatic behaviour over a wide area into statistics that are
representative of the whole area. The user should note that any single
country may contain substantial spatial variations of climate within it,
and that climate changes over time.

This data set
should *not* be used to represent climate at a point, or for sub-regions
of the countries and territories supplied here. If climate data is required
for points or sub-regions, enquiries should be made to the national meteorological
agency of the country concerned.

This data-set should only be used for time-series analysis (e.g. trends or regression) with the greatest of care. This data-set is based on the CRU TS 2.0 grids, and the discussion of the limitations on the use of that data-set is relevant here.

Please note that the standard deviation data may include influences from the changes over time in the station networks contributing to the underlying grids (see discussion). Therefore, particularly for smaller countries and data-sparse regions, the 'standard deviation' presented here may not be entirely climatic, but also a function of the number of observations.

The credibility of the data set rests upon observed grids previously constructed (CRU TS 2.0 - see details of the original data). The work of this author was to aggregate the grid box values into averages representing countries and territories (see details of the data processing).

For many countries,
the accuracy is better for more recent decades than for earlier decades
of the 20th century (although data is provided wherever possible). In addition,
the *useful* precision of the data may be less in earlier decades
of the 20th century (although the recorded precision is constant throughout).
For some variables and countries there is insufficient data to make a reasonable
estimate of year-to-year variations in the early part of the 20th century;
in such cases, the values recorded are 'relaxed' towards the average from
1961-1990, and therefore are not representative of the real-world year-to-year
variations.

One climatic season (December-February) overlaps from one calendar year to the next. The value we supply begins in the December of the year recorded, and ends in the February following the year recorded. Therefore the last year recorded always contains the missing value (-999.0) in the DJF column.

Further information may be obtained from the research paper published in Area. An electronic version is available.

Data
Structure

The average
climate is available as:

- Web pages, each with all the variables in a single country ('average' column in Table); this contains the 30-year mean only.
- ASCII files, each with all the countries for a single variable (Table); this contains the 30-year mean and the inter-annual standard deviation for the same 30-year period.

- ASCII files, each with one variable in one country (right-hand columns in Table).

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 TYN CY 1.1 and attributed to the following publication:

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
bears no responsibility for the accuracy of the data set. The countries
listed below include a variety of sovereign states, dependent territories,
and disputed territories. No political statement is being made by the inclusion
or exclusion of a particular territory, or by the labelling of a particular
territory by a particular name.

Data
Processing

The original
data took the form of a value for each month and each box on a 0.5 degree
latitude / longitude grid (CRU TS 2.0).
We assigned each box to a single country. For each country we calculated the weighted mean of the values from its constituent
grid boxes for each month in turn. Each grid box was weighted by surface
area, using the cosine of the latitude. The seasonal and annual values
are the means of their constituent months.

Original
Data

Station observations
were first collected by national meteorological, hydrological and related services,
and were acquired through the free and unrestricted exchange of meteorological
and related data. These observations were gridded. The gridded data-set is publicly available, and is being
published in a peer-reviewed scientific journal:

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.