Slashdot Mirror
Recipe for a Storm — Forecasting a Hurricane Season
University of Wisconsin-Madison researchers investigating the ingredients that go into a hurricane think they have found a reliable basis for predicting the overall strength of a hurricane season. Jim Kossin and Dan Vimont have found a basin-wide circulation pattern that offer one possible explanation in the previously unexplained differences in long-term hurricane trends. "Kossin and Vimont, a professor in the Department of Atmospheric and Oceanic Sciences, noticed that warmer water is just one part of a larger pattern indicating that the conditions are right for more frequent, stronger hurricanes in the Atlantic. The atmosphere reacts to ocean conditions and the ocean reacts to the atmospheric situation, creating a distinct circulation pattern known as the Atlantic Meridional Mode (AMM). The AMM unifies the connections among the factors that influence hurricanes such as ocean temperature, characteristics of the wind, and moisture in the atmosphere."
but but global warming...?
If you mod me down, I will become more powerful than you can imagine....
In reality, people have to realize that predicting weather is an inherently unstable mathematical problem, so longer-term forecasts are usually not that accurate.
And probably never will be. When I studied meterology in college years ago, I remember the complex math in Methods In Climatology, one of our textbooks, and it was every bit as bad as the math I had to take for physics. And that was 30+ years ago - it's only gotten even more complicated since...
-- Ed Carp, N7EKG erc@pobox.com PGP KeyID: 0x0BD32C9B What I'm up to: http://intuitives.mine.nu
These guys aren't the first to "discover" this connection. The article does a piss-poor job of explaining it, but basically the global thermohaline circulation varies in speed. Sometimes it runs fast and sometimes slow. The fast periods tend to last about 15-20 years, with the slow ones a little shorter, and it's a self-correcting cycle. Our observed records of this pattern correspond very well with the last hundred years of Atlantic hurricanes.
Global warming is a major threat, and it's going to be responsible for a lot of weather problems, but Atlantic hurricanes aren't one of them. Once you increase Atlantic surface temperatures to a certain point, you actually tend to increase upper-level shear, which is extremely disruptive to hurricanes.
The 2005 season was so terrible because four of the storms that made landfall passed over the extremely warm loop current in the Gulf of Mexico shortly before making landfall. It was a busy season and we just had some really bad luck on top of it. Even considering this, they were all weakening when they actually hit, and the destruction of New Orleans is entirely due to shoddy construction of the levees. Katrina may have been a cat 5 at sea, but the levees failed in category 1 conditions.