Vergent,
Quite different? Yes the mean will look different from the anomaly because the anomaly simply shows the difference from the long term mean.
Anyway, here's the June/August plot in the same manner as the plot you quoted.
Needless to say I can't do the JJA plot because all of August isn't yet in. The plot above does however show how different 2013 has been so far (when August is in it will merely strengthen that).
Going back to my earlier plot.
Notice the slight raising in GPH relative to 1977 to 2006 over Eastern Siberia, next to the Bering Strait.
Here's part of what I've been working on, I'd intended to blog in early September, but will give a teaser now...
Now look at a plot I did a few weeks ago for May GPH difference from 1977 to 2006 mean.
And here are timeseries of JJA GPH over Greenland, and May GPH over a box covering that region of Siberia. I've calculated anomalies from the 1981 to 2010 mean, normalised to that mean, then subtracted from those values the general rise in the atmosphere at 500mb across the northern hemisphere north of 30degN (Arctic and extra-tropical). This rise seems to be associated with anomalously early retreat of the snowline in that region causing warming of the surface which causes the ridge (high pressure).
Note that for both regions at different times the atmosphere is rising after 2007, and May 2007 preceded the 2007 crash!!! How might the two be connected?
That's a plot of GPH in metres for the 500mb pressure level, i.e. the height at which 500mb pressure is found. The Jetstream flows left to right, as indicated by the black arrow. R means ridge, T means trough. In the first image of this message the summer deep reds over Greenland are due to a higher than normal ridge, there's typically a ridge there but since 2007 it's been higher as in the timeseries plot preceding.
The question is - what is the link between the May Siberian ridge anomaly, and the summer Greenland ridge anomaly? Unlike the Greenland ridge the May Siberian ridge doesn't persist into the summer. But does it have a set up role for the summer pattern? What's the role of sea ice? Does Bluthgen's finding of sea ice in 2007 affecting the atmosphere to cause the dipole to persist all summer also apply to other 2007 years?
