Thursday, February 12, 2009

Hurricanes: looking back at 2008, ahead to 2009

From the Houston Chronicle's SciGuy*:
Looking back: If you've got a broadband connection, point your browser here to download an excellent movie showing all of the 2008 hurricane season storms against a backdrop of sea surface temperatures.
Not only does the movie look cool, it shows how large storms cool the water after crossing the ocean as they churn colder, deep water to the surface....
...From the outlook:

Ongoing analysis and projections for the upcoming Atlantic hurricane season are pointing toward another active pattern based on two key factors: water temperature anomaly profiles over the Tropical Atlantic and ENSO (El Niño Southern Oscillation) signals.

Warmer-than-normal water is directly proportional to tropical cyclone formation and development; the warmer the water in comparison to normal, the better the chance of seeing enhanced tropical development. Also, during an El Niño phase we typically see enhanced wind shear develop over the Tropical Atlantic, which in turn will suppress tropical cyclone development.

Near normal or neutral ENSO's typically exemplify very active tropical cyclone seasons with significantly less wind shear....MORE

For the first time in 79 months, Atlantic sea surface temps are slightly negative. This does not mean the warm phase of the Atlantic Multi-decadal Oscillation, which we entered in 1995 has ended, but it will make this season interesting and perhaps more profitable for those who can figure out the interplays (e.g. cooler Atlantic SST's combined with La Nina might mean fewer hurricanes but more East coast landfalls).

For more on last year's action, Dr. Jeff Masters shows what real science is all about. He is pretty much convinced of the role that AGW plays in changing climate but he presents facts that some might think undermine the hype-and-tout of the political types. From WunderBlog:

The global tropical cyclone season of 2008: below average
It was a below average year for global tropical cyclone activity, and the destructive power of these storms was close to the lowest levels observed since since reliable records began in the early 1980s. However, the the total number of global deaths from tropical cyclones was the highest since 1991, thanks to the estimated 140,000 people killed in Myanmar from Tropical Cyclone Nargis.

The total number of storms world-wide was 90, slightly lower that the average from the past 25 years of 92 (Figure 1). The global number of hurricanes, intense hurricanes (Category 3 and higher), and Category 4 and stronger storms were all below average. Only one Category 5 storm was recorded in 2008--Super Typhoon Jangmi, which attained winds of 165 mph at 06 GMT on September 27, as it approached the north coast of Taiwan. The last time so few Category 5 storms were recorded globally was in 1974, when there were none. The 2008 hurricane season was much above average in the Atlantic, but the Atlantic only accounts for about 13% of all global tropical cyclone activity....

Figure 2. Global (green) and Northern Hemisphere (blue) Accumulated Cyclone Energy (ACE) 24 month running sum through December 31, 2008. Note that the year indicated represents the value of ACE through the previous 24-months. Image credit: Ryan Maue, Florida State University....MORE
*A couple more SciGuy posts:
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