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Supercomputers Race to Predict Storms
pillageplunder writes "CNN has an interesting article on how different supercomputers from around the world are working to predict large storms tracks. The 3 days it takes now has been cut in half. Cool read."
It's easy to think this looking at the paths, but it is not true. Guidance is generally greatly affected by the placement of high-pressure ridges and their future erosions/strengthenings. Frances could have just as easily turned harmlessly to the north had there not been a strong ridge keeping it where it was, and Ivan could have headed east to Mexico had the ridge to the north not eroded. In both cases, they behaved roughly as predicted. The paths of hurricanes are predicted fairly accurately these days, and it is mostly due to these models.
The most difficult part of the job is predicting hurricane intensity, which is not fully understood. That's why Charley caught everyone off-guard when it abruptly strengthend, and similarly in 2002 there was unexpected relief when Lili (who looked a lot like Ivan) weakened overnight just before it hit land.
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Fortran compilers are guaranteed that the programs do not try to do strange things behind their backs (such as pointer aliasing). Therefore they can make optimizations that would be almost impossible to prove valid in, say, C. Also, Fortran numerical libraries are of very high quality.
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Big difference between casual observer and what the people doing the modelling are doing ;) To predict the EXACT track/intesnsity/storm surge/rainfail is going to be impossible...there are just way too many factors that determine what any particular storm will do at any given time. Same thing with earthquakes, flashfloods, tornadoes, etc. Have you read any of the Discussions on the National Hurrican Center's website for storms? They have many different models and then try to figure out which one is more accurate...and it's not where the storm was or is that's important, but what's going on in the atmosphere all around it... it's not something simple. And it's hard to make accurate predictions with limited data. And the predictions are getting better... I'd imagine the area of coastline that got smaked by Charley was under a hurricane warning at the time of landfall, right?
Everyone that lives in hurricane prone areas SHOULD be prepared for this type of thing. I'd rather be overly cautious with a major hurricane barrelling down on me... If you don't like dealing with the possibility of tropical cyclones, move inland :)
Weather simulation is not a tast you can cut up into a bunch of smaller tasks and farm out. If you cut the atmosphere up into lots of little chunks to model, after each step every chunk needs to know what the results from all the chunks around it where.
If you're waiting for those results at Internet (Latency: 100ms) speeds instead of intra-system speeds (latencyL 1 us) it takes you 100,000 times as long to get your data.
With SETI, all you do is get the data once, compute, and send back the answer.
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