Naked Science Forum
Life Sciences => The Environment => Topic started by: norcalclimber on 30/03/2010 00:18:17
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http://en.wikipedia.org/wiki/South_Atlantic_Anomaly
"The South Atlantic Anomaly (SAA) refers to the area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface. This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher than usual levels of radiation. The effect is caused by the non-concentricity of the Earth and its magnetic dipole, and the SAA is the near-Earth region where the Earth's magnetic field is weakest."
"Current literature suggests that a slow weakening of the geomagnetic field is one of several causes for the changes in the borders of the SAA since its discovery. As the geomagnetic field continues to weaken, the inner Van Allen belt gets closer to the Earth, with a commensurate enlargement of the SAA at given altitudes.[citation needed] Some scientists, including Dr. Pieter Kotze, head of the geomagnetism group at the Hermanus Magnetic Observatory in the southern Cape, believe that the anomaly is a side effect of geomagnetic reversal."
Hurricanes(for those of us in the U.S.) begin their life cycle in the Sahara where rapidly changing temperatures cause powerful winds, and cross the Atlantic Ocean, sometimes gaining in strength and becoming hurricanes and striking the U.S.
Could the weakening of the geomagnetic field be allowing energetic particles to energize storm systems and increase the frequency and intensity of Atlantic hurricanes?
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Personally, I can't see it. The sort of tropical cyclones you're thinking of gain their energy from the warm water near the equator, whereas the SAA is quite a long way south, where the water will be quite a bit colder. Also, the Hurricanes that hit the eastern coast of the US are in the northern hemisphere too, and not the southern, where the SAA is located.
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The SAA is a long way south, but it's not like the lines are exactly clearly delineated, and it seems to be growing. Plus, it is a huge region of ocean which is getting a lot more energy from cosmic radiation. Hurricanes draw their energy from warm water, so couldn't ocean currents bring that warm water north from the SAA and provide more energy for hurricanes? Aside from currents, since heat radiates, wouldn't the whole Atlantic be at least a little warmer if the region under the SAA was warmer?
Plus, as I understand it, hurricanes and cyclones are caused by low pressure zones and the rotation of the Earth combined with higher pressure zones wanting to flow to the low pressure zones(to put it extremely simply). If the SAA allows more cosmic radiation to penetrate deeper into the atmosphere, couldn't that generate low pressure zones which the rotation of the Earth as well as high pressure zones could then cause to merge with and intensify existing storm systems?
The prime argument behind climate change seems to be that our climate is dynamic, and changes to one area can have profound and far reaching effects. Wouldn't that imply the SAA and it's expanding borders most definitely affect our weather in some way at least?