Data variables in a model need data sources. These data sources are the dataset files that we imported and they need to be specified before simulation can occur. One place to set the data source is in the Simulation Control dialog; the other place is on the Toolbar after the Set Up a Simulation button has been pressed.
Toolbar
| Ø | Press the Set Up a Simulation button. |
| Ø | Type in a run name (e.g., baserun.) |
| Ø | Type in the name of the converted dataset, cfc11, in the left hand editing box (the Data editing box just right of the integration method Euler) (or press the little button right of the editing box to choose the dataset). |
| Ø | Press the Simulate button. |
Another way of specifying a dataset for use in simulation data is to use the Simulation Control (below).
Simulation Control — Optional (Not PLE or PLE Plus)
| Ø | Click the Simulation Control button then click the Advanced tab. |
The Advanced tab contains settings for data files and optimization of models.
| Ø | Type in a name for the run (e.g., baserun). |
| Ø | Click on the Data Sources… button then click on the dataset cfc11.vdf then click Open (or type the name cfc11.vdf into the editing box right of Data Sources...). |
| Ø | Click the Simulate button. |
You will receive 3 warnings:
WARNING: Simulation starts before first time for exogenous variable - atmospheric CFC 11 releases.
WARNING: Exogenous variable - atmospheric CFC 11 releases - in range at time 1938.
WARNING: Simulating beyond range for exogenous variable - atmospheric CFC 11 releases - at time 1994.
When the simulation is outside of the range of the data the closest value of the data will be used. This means that before 1938 the first value for atmospheric CFC 11 releases will be used and that in 1994 and beyond the last value will be used.
Results
| Ø | Click on the Control Panel button, select the Datasets tab and double-click on the dataset cfc11. |
Because the model used the cfc11 dataset during simulation to provide data for one variable, the dataset baserun also stores the data for this variable.
If you have created your own model you should add the following Custom Graph definition:
| Ø | Click the Graphs tab and then click on the button Display to show the Custom Graph. |
OR
| Ø | Look at the behavior of the rates and levels in this model with the Graph and Causes Strip graph. |
The input data series atmospheric CFC 11 releases ends at time 1992 and this means that the last figure in the series (171.1) is used in calculations for any time greater than 1992. Because of this, the CFC 11 in Troposphere value stabilizes after about the year 2000, while CFC 11 in Stratosphere keeps climbing.
The consumption and release of CFC 11 is likely to continue to decline over the following years. Releases of CFC 11 are not likely to continue at a fixed rate as high as 171.1 Mkg/Year. Let's open a data series that contains an optimistic forecast for CFC emissions.
