Climateprediction Model

From Unofficial BOINC Wiki

The contents of the following article relates to Climateprediction.net (CPDN) only.

The title of this article is incorrect due to technical limitations. The correct title is Climateprediction.net Model.

[edit] General

A Climateprediction.net Model is a complete climate model which is given as a Work Unit by Climateprediction.net. Since a Climateprediction.net Model simulates the entire planet for a minimum of 45 years it normally takes weeks or months of CPU time on a Host.

The model divides the earth into lots of cells (73 Latitude by 96 Longitude by 19 atmospheric height) and also divides the time into half hour Timesteps. Lots of equations are solved for several variables for each cell. These equations involve referring to variables for adjacent cells.

Until the Coupled Model goes public, the ocean is simplified and called a slab. The slab can act as a heat source or sink which can to some extent simulate the effect of currents flowing. However, there isn't any real current nor turn-over (vertical motion) in the slab oceans so while a slab model can simulate a steady current it cannot simulate a dynamic change. This goes a long way to explaining "Cold-Equator" Runs.

[edit] Models Launched and Planned

For a basic understanding of what the project is trying to accomplish please read "An Introduction To The Science Behind Climateprediction.net".

The different models that Climateprediction.net (CPDN) has and will distribute are detailed below in time order. Therefore if you have joined recently you are likely to be running the Sulphur Cycle, or, if you started after February 2006 you will probably be running the Transient Coupled Model.

Classic Slab Model - The original experiment not under the BOINC System. This is a 3 Phase 45 year model. First Phase measures fluxes necessary to keep the model stable. Second control Phase tests whether the measured fluxes do keep the model stable. The third Phase includes a forcing of doubled CO2 to see how the climate reacts to such a change. This model is used in the OU short course but can still be used by those unable to run the BOINC versions.

BOINC Slab Model - this is the same as the classic Slab Model just released under the BOINC System.

THC - an investigation of how the climate might change in the event of a decrease in the strength of the ThermoHaline Circulation. This experiment has now been closed to new Participants as they have sufficient Results. It was a four phase model totalling 60 model years. The first three phases were identical to the above slab models. The fourth phase imposed the effects of a 50% slowdown in the Thermohaline circulation. The Climateprediction.net (CPDN) page is here.

Sulphur Cycle - an investigation of the effect of sulphate aerosols on the climate. This commenced on 26th August 2005. See Sulphur page. This is a pre-requirement for the Hindcast. It is a 5 phase model totalling 75 model years. Timesteps are around 70% longer making it around 2.8 times longer than the initial slab model. The Climateprediction.net (CPDN) page is here.

Coupled Spin-Up Model - inclusion of oceanic influences into the basic model in a more dynamic and realistic way than the initial Slab Model. This is a pre-requirement for the Hindcast. This is in progress but it is not planned to be publically released. The fastest 200 - 500 computers have been invited to join because it is a 200 year model and Results are needed by February 2006 for the Transient Coupled Model launch.

Transient Coupled Model. This comprises an 80 year Hindcast and an 80 year Forecast. The Hindcast is to test how well the models perform at recreating the climate of 1920 to 2000. This is also described as "experiment 2" on the strategy page. Estimated launch February 2006. The forecast of what will happen in 2000 to 2080 follows the Hindcast and this is described as experiment 3.

High Resolution Model - this will be a Slab Model as normal followed by a period calculating at high resolution. It is unclear whether/when this will be launched.