Re: ENSO and the Arctic Ice Sheet
Posted by
Mike_Doran on 7/11/2009, 11:45 pm
I sort of agree with the over hyped part for perhaps different reasons. El Nino since 98 hasn't been all that it was advertized to be, and based on that your opinion is not the only one out there. The numbers aren't that great anyway and not sure it yet meets the formal japanese definition anyway.
Here's the thing about electrics in this. First most lightning globally occurs about when the Arctic ice anomalies are showing up--but that's the time of year El Nino doesn't really matter. El Nino is more a late fall to early spring event. Why? because just like Carlos is getting help from displacement currents, the so called big Walker circulations which occur during El Nino depend on displacement currents from lightning. During the late fall there are fewer places for couplings to occur on earth for these currents to otherwise flow. The changes I believe humans are causing which are the most significant are 1) CO2 as a conductivity variant and 2) dams changing ocean electrical conditions. With respect to 1), the change expresses itself during peak lightning, which is not the winter when El Nino comes. So we aren't seeing bigger and badder El Ninos. With respect to 2), rivers dammed are going to flow less in the northern hemisphere's spring, but flow better in the summer as dammed water is released. So I think that the dams also take away from El Nino but might give false positives in the summer as water is released later.
This year too there is the wild card of the spotless sun. It's going to be hard to see how that plays out with the season, but I tend to agree with you that El Nino is an overplayed, and certainly not understood factor in the tropical storm season. BTW the Curry paper I linked shows that there are not the same suppression issues if the El Nino is expressed by warmer SSTs in the central tropical Pacific as opposed to the coastal east Pacific. To me, again, it has to do with where lightning flows. If there is a area of cold SSTs in the Pacific tropics between lightning in the Americas and where the warm anomalies are, it's like any wire that is cut--it cant carry an electrical current (colder means not conductive). Therefore the displacement currents tend to flow elsewhere, to include the electrical couplings that cause tropical storms in the Atlantic.
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