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George, the ocean dynamics are really hard to predict, particularly when the sun goes into one of it's bicentennial wobbly phases when activity falls far below normal. In general, I think we'll be seeing weaker el nino's and stronger la nina's from now until after solar max around late 2013. Then a couple of stronger el nino's out to 2017, followed by a BIG la nina and an overall fall in global surface temperature just in time for me to collect from Dean. :-)
The general observation I hoped everyone might spot on the ENSO graph from 1950 is that of the 18 El Nino events shown on the graph, 17 of them *start* (i.e. SOI rises above zero) when solar activity has peaked and is falling. The Exception is the small event at 1957, though even that one occurs just following a rapid downspike in solar activity near the peak of the cycle. Most of the big ones seem to start just before or just on solar minimum. Maybe this way of looking at it will help:
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I have a hypothesis about why that is. I'd like to work out a way to test the idea with an experiment, and I think Roger Caffin could help me if he's willing.
When I noticed an interesting correlation between solar activity levels and humidity high in the atmosphere, it got me thinking about the many billions of tons of water there is in the atmosphere. Here's the correlation:
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Now, when solar activity is high, the atmosphere and ocean is directly warmed by the Sun more, and this causes more evaporation and an expanded atmosphere carrying more water vapour higher up. This will increase the gravitational potential of the atmosphere and therefore air pressure at sea level. When solar activity drops, the reverse happens, and I think this may be the cause of the sudden upwellings of energy from the ocean that characterise El Nino events. A bit like when you open a bottle of carbonated beverage and the drop in pressure causes the bubles of gas coming out of solution and rising. Indeed, the ENSO index is a measure of sea level pressure differences between Tahiti and Darwin, so there is already a known connection between SLP and ENSO. I want to see if overall pressure changes rather than differentials which also have an effect.
To test this, we could devise some apparatus whereby we have a container with water in, and an airspace above. A couple of digital turkey thermometers let in near the surface and base, and a schreader valve and tyre pump to change air pressure.
I know Roger has some nice equipment for measuring temperature over time and logging the data...
Edited by tallbloke on 06/13/2011 12:40:51 MDT.
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