Forcing
From Unofficial BOINC Wiki
[edit] General
Some things which you do not think of as part of the climate nevertheless have a huge effect on the climate - such as volcanoes (after Pinatubo erupted in 1991 the ash it spewed out affected the climate for several years), solar activity and, of course, the composition of the atmosphere. We call these things Forcing mechanisms, as, when they change, they force the climate to change.
If something is internal to the model then it is called a Feedback rather than a Forcing. Therefore the effects of water vapour are included in climate models even if they do not appear in a list of Forcings because it is considered to be a Feedback.
See RealClimate on why water vapour is a Feedback.
The only Forcing being applied in the current experiment 1 is a doubling of CO2. This is not realistic but the scientists are doing this to find out more about the model so that they can be more efficient when it comes to later experiments which will be intended to be more realistic.
The THC experiment has an extra Phase with an extra Forcing of an imposed slowdown of the ThermoHaline Circulation.
The Sulphur Cycle experiment will have 5 Phases where 2 of them have an extra Forcing of increased sulphur emissions.
The Transient Coupled Model will be the first model to be given realistic Forcings.
A set of realistic Forcings is known as a Scenario. The most commonly used scenarios are the SRES scenarios and Climateprediction.net (CPDN) uses the IPCC A1B and B1 scenarios.
[edit] Also See
Things that affect the outcome of climate models include:
- Parameters Settings used by the model.
- Initial conditions - Initial condition do affect the weather but generally initial conditions are found not to affect climate much. Initial conditions can be considered to be a Parameter.
- Forcings Changes like greenhouse gas levels that force the climate to change.
- Feedbacks Things like water vapour (which is a greenhouse gas) but the level is determined by the model rather than forcing the model.
RSS Feeds
