Atmosphere And Weather

What was Project Stormfury



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Project  STORMFURY was an experimental research program that was designed to study hurricane modification. It was carried out between 1962 and 1983 by NOAA (National Oceanic and Atmospheric Administration,) and the government agency that preceded NOAA. It was, in essence, government supported research into possible methods for modifying hurricane behavior. Over the course of roughly two decades, NOAA and an earlier government agency attempted to weaken hurricanes. The modification technique as they had proposed it, involved the artificial stimulation of convection outside the storm's eye wall.

*What was proposed  -

Basically, a silver iodide would be seeded into the storm. The argument was that the invigorated convection would have to compete with the original eye wall, and this would cause the eye wall to reform with a larger radius. Because of a larger eye wall radius and through the partial conservation of angular momentum, there would be a decrease in the strongest winds.

It was also believed that because the hurricane's destructive capabilities rapidly increase as the strongest winds become stronger, even if the reduction was only as small as 10%, it still would have been worthwhile.

*What was done -

To gather information, a silver iodide (a material that functions as an effective ice nuclei,) was dropped into the storm's rain bands. These experiments were done far out over the Atlantic Ocean and away from land. The clouds that they targeted were the convective clouds just outside the storm's eye wall.

During the years in which scientists were gathering data, they seeded clouds (or dropped the silver iodide) into the storm's rain bands. The storms that the silver iodide was dropped into were Hurricane Esther (1961,) Hurricane Beulah (1963,) Hurricane Debbie (1969,) and Hurricane Ginger (1971.)

The modification was attempted on four different hurricanes, and the readings would be done over 8 days for each hurricane. On four of the eight days, wind decreases ranged from 10% to 30%. On the other days, there was no response. That lack of response was deemed to be either the result of faulty execution of the seeding or because of poorly selected subjects.

The clouds that were targeted were the convective clouds just outside the storm's eye wall. The goal was to form a new ring of clouds that would, or so it was hoped, compete with the storm's natural circulation and weaken it. The idea, as researchers conceived of it, was to use the silver iodide to enhance the thunderstorms of a rain band, and do that by causing supercooled water to freeze.

They believed that this would then free the latent heat of fusion and help the rain band grow, but at the expense of the storm's eye wall. It was hoped that because of the weakened convergence to the eye wall, the strong winds of the inner core would also be weakened. The cloud seeding could only be successful, however, if the clouds contained enough of the supercooled water (this is water that is capable of remaining in a liquid state, even in temperatures below freezing or 32 degrees.)

*Findings from the 1980's and the fatal  flaw -

by the mid 11980's, however, the promising results came into question because observations in the unmodified hurricanes showed that though the idea was great, it proved to have fatal flaws:

1.) There was little possibility that cloud seeding could be successful because the hurricanes had too much natural ice and not enough supercooled water. What this means is that hurricanes lack enough of that supercooled water for STORMFURY's seeding to work.

2.)The belief that the positive results that were interpreted from the 1960's seeding experiments were the result of an inability to discriminate between what was expected from human intervention and the natural manner in which hurricanes behave.

Another reason that the project failed is because even unseeded hurricanes can form natural outer eye walls in the same manner that researchers expected to find with the unseeded ones. The result of that is that it is virtually impossible to distinguish the effect of seeding from changes that occur naturally. In other words, on those few occasions when they did seed and observed a reduction in intensity. What they were seeing was most likely due to something that is now called "concentric eye wall cycles."

Ultimately, nature accomplishes what NOAA scientists were hoping to do artificially. It isn't surprising that NOAA researchers believed that their early experiments were successful. After determining that the results of NOAA's seeding experiments were inconclusive, STORMFURY was discontinued altogether.

The idea that scientists might be able to modify hurricane behavior was a novel one, and had it worked, it might been possible to reduce the intensity of the most devastating hurricanes, thereby saving lives and property in the process. When nature does things in its own way and on its own time, it can be very difficult, if not impossible to try to alter the behavior of something as powerful as a hurricane. Nonetheless, scientists and meteorological researchers have learned a lot about hurricane behavior.

SOURCES:

AOML Laboratory: Has there ever been an attempt or experiment to reduce the strength of a hurricane? -

AOML at NOAA : Project STORMFURY -

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