We intend to include these forcings (with both seasonal and interannual variability) in the seasonal, annual and multiannual integrations, taking into account that the volcanic forcing should not be used during the hindcast and that the other forcings would have to be linearly extrapolated.

A list of the datasets suggested for some of these forcings follows. Note that data for some of the forcings are not available yet.

Greenhouse gases

The data and their documentation, prepared by Jean-Francois Royer, can be accessed here. Note that there is a CFC-11 equivalent concentration of all other minor species minor species of CFCS, PFCs and HCFCs included in the SRES table II.2.10 and table II.2.4. The radiative forcing of all these halogenated compounds have been taken from the WMO/UNEP Scientific Assessment of Ozone Depletion: 2002 table 1-6 page 1.32-1.33. The total of the radiative forcing of all these halogenated gases, except CFC-12, has been converted back into the equivalent CFC-11 concentration (CFC-11*) that gives the same radiative forcing. There is a small CFC-11* preindustrial concentration ( 12.48 pptv) that comes from the fact that there are natural sources of CF4 and evidence that the natural concentration of this gas is about 39 pptv (Harnish et al, 1996. Effect of natural tetrafluoromethane. Nature, 384, p 32).

Sulphate aerosols

If partners are able to include this forcing, the dataset prepared by Olivier Boucher for SRES scenarios is the option suggested. The aerosol files and documentation from Olivier Boucher are now available on the RT2A site. Follow the links "Member's site" and "Forcing data" from the menu in the left frame to get to the bullet "Sulfate aerosol forcing concentration: Olivier Boucher". Two links point to the documentation and to the NetCDF with the aerosol concentration, which are part of the CNRM DODS server. The username and password are available upon request from Jean-François Royer.

Ozone

The ozone fields for the stream 2 simulations for years 1850, 1900, 1950, 1980, 2000, and 2100 for scenarios A1, A2 and B1, are available as monthly means (NetCDF format) on a server at the University of Oslo. For more information on the dataset contact Bjørg Rognerud bjorg.rognerud@geo.uio.no. An alternative ozone dataset is offered by the IPCC.

Black carbon

An option to include black carbon is offered by Nozawa's dataset (not available yet).

Solar activity

A monthly solar irradiance dataset has been prepared by Eigil Kaas from the original Krivova and Solanki's series.

Volcanoes

The influence of volcanic aerosols has not been taken into account in the stream 1 hindcast, except for the Met Office integrations with DePreSys. DePreSsys adds up the volcanic aerosols (previously splitted in four latitude bands) at the hindcast start date damping the values as an exponential decay with a time scale of one year. The data used and an example of their application have been made available by Doug Smith. The initial conditions already contain the impact of previous volcanic eruptions, but it is not clear how long the model is able to keep this information for. Modellers are invited to include the volcanic aerosol effect in the stream 2 hindcasts following the strategy already tested by the Met Office. For reference, a dataset of stratospheric aerosol optical thickness including the volcanic effect can be obtained from NASA.

26.03.2007