Southern Africa Region
Southern Africa is a region which generally experiences a hot wet season with plenty of thunderstorms and a cooler dry season with essentially no rainfall. In "weatherathome" the model region encompasses the whole of Africa below about the Equator, together with Madagascar.
The images below give an idea of the sort of information scientists will be investigating as the results are returned from the "weatherathome" Southern Africa experiment.
In this particular example the cloud structure over Southern Africa (below) shows a striking ‘C’ shape which is mirrored in the corresponding map of rainfall below it, where the heaviest rain – the purple colours – is apparent in a very spotty structure. Thick clouds just north of Madagascar are bringing particularly heavy rain.
In this particular December example the surface pressure and temperature (below) are fairly uniform, indicating a fairly stable weather regime at this time.
What experiments are planned for this region?
Currently three experiments are planned for the Southern African region of "weatherathome":
1) The first experiment is intended to help document Southern African climate, and increase our knowledge of it. Unlike other regions of the world, there are few observational measurements over much of this region. If we generate many simulations of what the weather could have been over the 1960-2010 period, these should help us determine the relevance of the observations we do have to the places where we do not have measurements. We may also be able to use the data from the model simulations to derive methods of "filling in the gaps" between measuring stations. Finally, by comparing trends in both the observations and the model simulations, we should be able to get a better idea of whether unusual damaging weather events have been becoming more or less frequent over the past few decades.
2) In order to make simulations manageable on today's computers, climate models have to take "shortcuts" in representing some of the more complex processes in the climate system. This experiment will test the sensitivity of the results of the first experiment to how those shortcuts are implemented. In particular we will investigate the effects of the shortcuts used to represent thunderclouds, and the interaction of the near-surface with the free atmosphere.
3) What might the weather have been like had humans not interfered with the climate system? This experiment will modify the driving conditions fed into the model to reflect what conditions would have been like if humans had not emitted greenhouse gases and done other things which affect the climate. The difference between these simulations and the results from the first experiment will provide an indication of the human contribution to recent weather trends.
Researchers at the University of Cape Town will be coordinating the Southern African part of "weatherathome". They will welcome suggestions for further experiments.
