I joined the climate prediction experiment a few months ago and am now running phase 2. According to the article found at
http://www.climateprediction.net/science/strategy.php

phase 2 of the experiment is :

2
Simulation of 1950-2000

[tell me more] Assess model skill by making a
probability based forecast of the past climate.
Run the model with a range of initial conditions
and parameters for the period 1950-2000. Compare
model ou..

When I choose the menu item to see the results of my model run the model date shows 1833.
It also shows I am in phase 2.

Does anyone know why my model date is not in the 1950's? Can someone point me to the
relevant information about my model run?

Thank You,

Kathy Poliakoff

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Hi & Welcome

You are mistaking phase II of the model (the Wu you're crunching) and Phase II of climateprediction.net project.
We are presently in Phase I of the CPDN project: this means that we are crunching the hadsm 4.xx model (with a slab ocean). This model includes three phases: 1810-1825, 1825-1840, 2050-2065. You're presently in the Phase II <b>of the model</b>: 1825-1840.

More infos <a href="http://www.climateprediction.net/science/strategy.php">here</a>

You can read: <i>

Experiment 1
This experiment is more about learning how the model reacts to changes in initial conditions and parameters than about actually trying to replicate the Earth's climate. For this reason, the model we use has a sophisticated atmosphere, but a simplified ocean (a single layer, 'slab' ocean). This means that some aspects of the climate system (such as oceanic currents, and the El Nino oscillation) are not replicated, but the model runs a lot faster and a lot more calculations can be completed.

The knowledge we gain from this experiment about the way the model reacts to changes to the parameters will be used to design the next phases of the climateprediction.net experiment - combinations of parameters that obviously do not work can be avoided.

The experiment consists of 3 separate phases, each model which is distributed completes all 3 phases from a unique set of initial conditions:

Calibration step(phase 1)
Phase 1 is the calibration phase of the experiment. In this phase, the temperature of the surface of the ocean is artificially held constant. The movement, or flux, of heat, in or out of the ocean that is required to keep the ocean at a constant temperature is calculated. This is an easy solution to having a very simple ocean in the model, which cannot actually store heat in the way that a real, deep, complex ocean can. The dates given to this phase are 1810-1825.
Pre-industrial CO2 step (phase 2)
This is the control phase. This involves running the model for 15 years with the levels of CO2 in the model atmosphere kept constant at pre-industrial levels, 282ppm. Unlike phase 1, here the temperature of the ocean surface is allowed to vary, according to how much energy the ocean receives and emits. However, it is safe to assume that the amount of heat flowing into the oceans is the same as in phase 1, so the heat fluxes calculated in phase 1 are applied. Unless the atmosphere starts doing something very different, and the energy balance at the top of the atmosphere is changed, the temperature of the whole atmosphere should therefore stay the same. If this is the case, the globally averaged surface temperature should also be approximately constant and not change substantially from year to year or drift off to a very different temperature, and we say that the model is stable. The dates given to this phase are 1825-1840.
Double CO2 step (phase 3)
In this phase the levels of greenhouse gases (you can read more about the Greenhouse Effect here) are doubled and the model is run for a further 15 years. In a good model, the atmosphere should adjust to this change in forcing and eventually settle in a new stable, equilibrium state (which may be the same, warmer or cooler). The dates given to this phase are 2050-2065.
The results will give an indication of what combinations of parameters work (in terms of producing an atmosphere that behaves in a similar manner to reality and does not freeze or boil, or oscillate in and out of ice ages on a timescale of a couple of years). We will therefore be able to use the results to guide our choice of parameters in the main experiment.
By comparing the single and doubled
</i>

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Arnaud

Thank You

Kathy Poliakoff

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