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| Assignment Section | Unacceptable Standards | Acceptable Standards |
|---|---|---|
| I. Explore the present climate | Response shows evidence that the simulation was not actually done. Response does not make appropriate analogy to climate simulation. | Demonstrates understanding of the relation of weather variability to climate statistics. |
| II. Explore an Ice-Age Climate | No simulations reported. No analogies made linking present climate to ice age climate. | Demonstrated understanding of the statistical relation of weather and climate of an ice age with the present conditions. |
| III. Explore the Impact of Increased Greenhouse Gas Concentrations on Global Mean Temperature | No simulations reported. Lack of understanding of how boundary conditions affect outcomes. | Demonstrated understanding of how changes in boundary conditions affect individual days (weather) and how they affect climate. |
| IV. Explore the role of Clouds on Global Mean Temperatures | No report made. No inference drawn to effects of clouds. | Appreciation demonstrated for the complicating and compensating effects of clouds on surface temperatures. |
| V. Explore the behavior of a heat wave during drought conditions. | No simulations reported. Lack of understanding of the role of initial conditions and boundary conditions. | Recognition of the compounding effects of conditions that independently lead to higher mean temperatures. |
Assignment: Understanding Climate Simulation The Pinball Machine Analogy
Click here to access the Climate Simulation.
Procedure
Assume that each path of a ball through the matrix represents weather over a year. If the matrix has no been changed and the balls are dropped from A, they will form a symmetric distribution at the bottom with a mean value of zero (it may take several hundred balls to get a smooth distribution with mean very near zero). One can think of any departure from zero to be the temperature change (in degrees C) from the long-term climatological average. The final position of any single ball at the bottom represents the departure of the global mean temperature of the year represented by that ball from the long-term annual mean.
| A. | Explore the climate of a typical year for initial condition
A.
Run a single year and observe the departure of the temperature for that year from the long-term mean (drop a single ball from position A and observe where it ends up). Run a second year and see how it relates to the first. Repeat until you have a sense of the year-to-year variation (interannual variability) of the global climate. |
| B. | Construct a "short-term" climatology of global mean temperature for
initial condition A. Run 10 years (drop 10 balls from A, done by selecting "10" rather than "1"). Record the mean and standard deviation and make a mental note (or perhaps sketch) of the distribution. Repeat a couple of times and observe the results for sampling "different decades". Be sure to reset the machine between experiments so that each decade creates its own distribution. Report your results of attempting to determine the true mean temperature from just 10 measurements and also the "interdecadal" variation (the difference in mean, standard deviation, and shape of the distribution for two or more 10-year experiments). |
| C. | Construct a long-term climatology of global mean temperature for
initial condition A. Run a 100-year simulation. Record the mean and standard deviation and note the shape of the distribution. Without resetting, run another 100 years to give a 200-year climatology. Again note the results. Repeat a couple more times and note results. |
From the three parts report the following:
The surface temperature during the Little Ice Age of the 1500s and 1600s was substantially lower than present values. We simulate the external constraints causing this phenomenon by removing pegs from the left half of the matrix and adding pegs to the right half. Remove 10 pegs between A and -C, and add 10 pegs between A and +C. Your particular choice of pegs will create your own unique Little Ice Age climate.
| A. | Repeat the procedure of I.B using your Little Ice Age matrix and compare your new results with those of I.B. Are there any years from your Little Ice Age climate that have the same annual mean temperature as the present climate? |
| B. | Repeat I.C with your Little Ice Age matrix and report the mean and standard deviation of mean global temperature for the Little Ice-Age climate. |
| C. | What is the level of confidence (qualitative) that the Little-Ice-Age condition gives a different mean temperature from the present climate? |
Greenhouse gases change the heating rates and patterns, which we also simulate by adding or removing pegs in the matrix as follows: Remove 10-15 pegs between A and +C. Add 10-15 pegs between A and -C. Again, your choice of pegs will make your climate unique. Repeat parts I.A,I.B and I.C.
| A. | Report your experimental conditions (approximately where you added or deleted pegs) and your results. |
| B. | Compare your statistical results (both mean and standard deviation) and your assessment of individual days of the present climate (I.C), ice-age climate (II.B), and greenhouse-gas climate (III.A). |
Clouds lead to a lowering of global mean surface temperatures by reflecting visible radiation back to outer space. Clouds also lead to surface warming by re-radiating infrared radiation downward toward the earth.
Change 12 pegs (add some and remove some, your choice) on the right half of the matrix (warming by clouds due to trapped longwave radiation) and do the opposite on left half (cooling by clouds due to reflection of solar radiation) and see whether the result leads to net warming or cooling. Try different combinations. Report your configuration and whether you observed a warming or cooling.
A dry surface uses less energy to evaporate water and more energy to heat the lower atmosphere. This may exacerbate a heat wave.
| A. | Remove 10 pegs from a vertical column between A and +C (warming due to more absorption at the surface) and release the balls from A. Compare your results with I. C. |
| B. | Clear the matrix and repeat V. A. except release the balls from +C (heat wave). Compare your results with V. A. |