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Thursday, September 20, 2012

States of Climate

Hopefully, this simple diagram will explain to many what I am searching for, the states of climate.  Not every possible state, just the more common states that generally cause shifts in climate.  R is the distance from the Thermal equator to the average sea ice extent or equivalent thermal sink potential.  Currently, climate is moving closer to the 1.5R state or where the thermal capacity of the oceans are roughly in balance.

Added: For those that have not been following, the true equator is a natural boundary for atmospheric circulations, but due to the location of the land mass and oceans the Thermal Equator or center of the average thermal mass of the planet is south of the true equator.  That changes the thermal equator to polar heat sink transfer times creating an natural oscillation potential.

The upper state, R versus 2R, would be the most unstable climate state and R versus R would be the more stable glacial period state.  While the 1.5R state would appear to be equivalent to the R state, the 1.5 State allows more uniform atmosphere and upper ocean mixing layer warming while decreasing instability.  This would be the high "normal" of the bi-stable climate regimes.  The R glacial state would be associated with the low "normal" of the bi-stable states.

Since the Earth is spherical, in the R state, separation between the thermal equator and the polar sinks would be at a minimum and the area of the polar sink would be at a maximum.  Polar cooling in winter would have less impact and the thermohaline current would have less impact on climate oscillations.  However, since climate would not impact tidal forcing, the more massive ice expanse would be less stable.  With more northern hemisphere ice "fixed" due to land mass, southern hemisphere ice would be more likely to dislodge and cause climate fluctuations.  With the right timing, this would cause a more rapid shift to the unstable R/2R state.

Interestingly, the average sea surface temperature would be nearly the same in both the high normal and low normal states.  The lower SST would be more associated with transistions as the more unstable atmospheric conditions would improve mixing of the upper ocean mixing layer and the deeper ocean layers.

 The exit from the most recent glacial maximum appears to be a fairly uniform rise from a more depressed or colder than usual state.
The exit from the glacial 135k years ago appears to be drive more by southern hemisphere event that lead the solar forcing increase and the CO2 rise in the EPICA ice core data.  So the last glacial minimum was more influenced by the longer solar reduction that the previous glacial period.  The actual lead would be impossible to determine with such coarse data, but there appears to be an unforced or at least less forced transition from glacial to inter-glacial.

So while everyone quibbles over other details, this is what I am working on.  This may have already been solved or refuted by someone else, but since I am playing with more non-standard methods, that really doesn't matter.

Update:  There is a new post on using network analysis to locate synchronization in climate oscillations over at Roger Pielke Jr.'s blog,

Guest Post “Atlantic Multidecadal Oscillation And Northern Hemisphere’s Climate Variability” By Marcia Glaze Wyatt, Sergey Kravtsov, And Anastasios A. Tsonis

They use a much more rigorous method.  What I am doing is more of a black art, but with a similar goal, to isolate synchronizations.  "Synchronization refers to the matching of rhythms among self-sustained oscillators; although the motions are not exactly simultaneous. If two systems have different intrinsic oscillation periods, when they couple, they adjust their frequencies in such a way that cadences match; yet always with a slight phase shift (lags)."  

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