Hurricane Erin raced across the North Atlantic and along theeastern seaboard in September 2001. She was used as an experiment for astudy to improve hurricane tracking and intensity predictions, allowingmeteorologists to provide more accurate and timely warnings to thepublic. Studies show that temperatures measured at an extremely highaltitude collected from a hurricane's center or eye can provideimproved understanding of how hurricanes change intensity.
HurricaneErin was analyzed during the fourth Convection And Moisture EXperiment(CAMEX-4), which took place from August 16 through September 24, 2001.The mission originated from the Naval Air Station in Jacksonville, Fla.The mission united researchers from 10 universities, five NASA centersand the National Oceanic and Atmospheric Administration. CAMEX-4 is aseries of field research investigations to study tropical cyclones —storms commonly known as hurricanes.
Twenty instrumentedpackages, called dropsondes, were dropped into Erin's eye by two NASAresearch aircraft (the ER-2 and DC-8). The special packages includedinstruments that mapped temperature patterns.
For the first time,researchers were able to reconstruct the structure of the eye in threedimensions from as high as 70,000 feet, down to the ocean surface, ingreat detail. The dropsondes showed Erin's warm core decreasing whileit was rapidly weakening, making the storm more vulnerable to windshear, a change in horizontal winds, which led to the storm fallingapart.
Hurricane Erin's rainfall pattern adjusted quickly tosurprisingly small changes in wind speed patterns in the surroundingatmosphere. Weak horizontal winds rearrange rain and wind structure,which create uneven weather conditions around the hurricane's core.
Observationsfrom the study show the relationship between warm air from the eye ofthe storm is linked to reduction in sea surface pressure, which is thebasic process that drives the hurricane's destructive winds.
Althoughlittle is known about the birth of a hurricane and what causes it tostrengthen or weaken, scientists have made substantial steps towardimproving predictions of where a hurricane will move or make landfall.The ability to forecast intensity change, however, has always been achallenge for meteorologists.
The research done on Hurricane Erinwas important because it could help forecasters understand factors thatcontrol rain intensity and distribution for hurricanes landing alongthe Eastern Seaboard.
Freshwater flooding is the number onekiller from hurricanes in the Western Hemisphere and the study of ahurricane's rainfall pattern could better prepare us for the next bigstorm.
This research paper, titled "Warm Core Structure ofHurricane Erin Diagnosed from High Altitude Dropsondes During CAMEX-4"by J. Halverson et al., is going to be published in an upcoming issueof the American Meteorological Society's Journal of AtmosphericScience, CAMEX Special Issue, at the end of 2005.
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