What does the DDC provide?

Location: DDC Home > About the DDC > What does it provide?

The DDC provides four main types of data and guidance, which meet certain criteria laid down by the TGICA. They are introduced briefly here and described in more detail throughout the web site and accompanying guidelines:

1. Observed Climate Data Sets

The climate observations comprise 1961-1990 mean monthly data over global land areas for nine variables on a 0.5º latitude/longitude grid, together with decadal anomalies from this mean for the period 1901-1995. This data set is currently being updated to 2000 and interpolated to a finer resolution (10 x 10 arc minutes). Pointers are provided to other relevant global climatologies.

2. Global Climate Model Data and Scenarios

One of the main goals of the Data Distribution Centre was to make available to the impacts community a set of recent GCM outputs that both reflect the state-of-the-art of model experiments and provide a representative range of results from different GCMs. To this end, the IPCC TGCIA defined a set of criteria that were applied to identify a small number of GCM experiments whose results could be deposited at the IPCC DDC. Models should:

be full 3D coupled ocean-atmospheric GCMs, be documented in the peer reviewed literature, have performed a multi-century control run (for stability reasons)and have participated in CMIP2 (Second Coupled Model Intercomparison Project).

In addition, the models preferably should:

have performed a 2 x CO2 mixed layer run, have participated in AMIP (Atmospheric Model Intercomparison Project), have a resolution of at least T40, R30 or 3º latitude x 3º longitude consider explicit greenhouse gases (e.g. CO2, CH4, etc.)

On the basis of these criteria, results of experiments at seven modelling centres are currently held by the DDC, with the possibility of others being added later if they too qualify for inclusion. Summary information on each model experiment can be found on the climate model period averages pages. Note that data from control run, ensemble and time slice experiments are also available for some models. Monthly averaged results from each model have been lodged with the IPCC DDC. For each AOGCM the following core variables can be found on the DDC, provided on a global grid that varies from model to model - cloud, diurnal temperature range, precipitation, radiation, mean temperature, minimum temperature, vapour pressure and wind.

Other period-averaged information that can be displayed and downloaded using the DDC visualisation pages:

diurnal temperature range, vapour pressure, daily temperature variance, and daily precipitation variance.

Some other variables can also be obtained for individual experiments.

The full sets of monthly results from these experiments (and more detailed technical information) can be obtained from the DDC GCM data archive pages. Daily fields are available from PCMDI or from the respective modelling centres.

The DDC visualisation pages allow the user to plot 30-year mean change fields from these experiments, comparing them with each other and with the 1961-1990 observed climatology. Ensemble members can also be plotted, as well as ensemble means. All 30-year mean GCM fields can be downloaded from the climate model period averages pages.

3. Socio-economic data and scenarios

This information is required for describing socioeconomic development and adaptation capacity. The reference data include country and regional level indicators of socio-economic and resource variables. The scenario data supplied extend to 2100 and are based on the assumptions underlying the new set of emissions scenarios developed for the IPCC Special Report on Emissions Scenarios, SRES, as well as the six emissions scenarios prepared by the IPCC in 1992, IS92. There is also detailed guidance on the use of DDC data to develop socio-economic and adaptation scenarios as well as links to related guidance material developed by other agencies.

4. Data and scenarios for other environmental changes

These include data on global mean CO2 concentration, global and regional sea-level rise, regional ground-level ozone concentration, sulphate aerosol concentration and sulphur deposition. All of these scenarios were developed for the IPCC Third Assessment Report based on the SRES emissions scenarios. Detailed documentation and guidance is also provided for the use of these data.

More information about the guidelines can be found here.

Location: DDC Home > About the DDC > What does it provide?

Page last modified: 22 July 2008