[geeks] Global warming, was Mr Bill?

[Dr Robert Pasken]

As a meteorologist specializing in numerical weather prediction models I 
can assure you that not only do climate models exist, but they work very 
well. Even the more complex problem of forecasting on very small scales 
(300 meter resolution) is working in slightly better than real time. 
Current generation microscale models are undergoing field verification 
tests. There are several DOE/DOD/DHS sponsored micro scale observing 
networks that are being used to verify the numerical forecasts from 
meso/micro scale forecast models. There are alot of reasons why this 
is  important. Think of the problem of a gas/particulate whose dispersion 
and chemical composition is dependent of the temperature, humidity and winds.
In this case not only do I need to worry about the meteorology, but the 
transport, diffusion, dispersion and deposition as well. Current 
generation meso/micro scale models can accurately predict the meteorology 
and dispersion/transport processes in better than real time. Although 
climate prediction is complex, it doesn't need to be concerned with things 
like turbulence around buildings which is ill-posed mathematically (the 
turbulence closure problem).

Most climate models don't start with "smoothed values" rather they start 
with the observed conditions at specified time in the past. The typical 
initial conditions for a short run (75 years) of a climate model is 
January 1, 1950. The model is run forward for 50 years and then compared 
against conditions on January 1, 2000. Another simple alternative is to 
take current observed conditions and run the model backwards to a a point 
in the past and compare model "forecast" conditions against observed 
conditions.

There are two reasons why supercomputers and now Beowulf clusters exist. 
One is bomb testing and the other is weather/climate prediction.