That connection between standard deviation and percentage of events isn't a universal law. It's a feature of the normal distribution, i.e. of distributions that are the sum of a large number of small independent components. I see no reason to expect that to be the case for sea ice extent or area.
On Jul 23, 4:11 pm, Veli Albert Kallio <[email protected]> wrote: > Hi All, > > I think that we all should call the Arctic Ocean melting by its rightful > name: "melt-away of the North Pole Floating Sea Ice Cap" to make people > understand the gravity of situation. > > Two events that stuck me: > > 1) > > Yesterday 22.07.2009 National Snow and Ice Data Centre (NSIDC), University of > Colorado, Boulder, removed the two standard deviation markers as meaningless > and of no useful further reference leaving the mean annual 1979-2000 average > against 2007 melting as references. One standard deviation indicates > variability of a stable system to 68% of occurrences, two standard deviations > incorporates occurrences to 95% of events. Usually, two standard deviations > that cover 19/20 cases are the cut-off point considered a stable system. As > there are, furthermore now three consequtive occurrences of the sea ice > melting falling outside this limit (2007, 2008 and now 2009) there are even > less reasons to believe that 1979-2000 average can be used as a reference. In > other words, NSIDC admits a passage of tipping point, a move away from system > prevailing 1979-2000. > > 2) The sea ice has had all this season very strong peripherial melting as > well as some of the strongest ice has been drained out through the Fram > Straight, losses have been high as sunlight and insolation on the long > exposed periphery is much more efficient to mop up suns heat than holes > appearing in the centre. A split has occurred from the vicinity of Peary Land > to Komsomoletski Island today, it needs to be seen wheter the currents keep > pulling these apart further and further. This channel was readily weakened by > melting north-west of Laptev Sea, today's images suggest the front part is > 'falling' to Atlantic. However, last year the re-freezing on the North Pole > began on 25.07.2009 - that may re-seal, unless the melting has advanced far > enough and ice thinned by previous stretchings too much. The tiny split on > the last remaining section, off Peary Land, occurring today. > > Thank God, we have such a good satellites and data to see these things in > real-time!! > > Kind regards, > > Albert > > _________________________________________________________________ > Celebrate a decade of Messenger with free winks, emoticons, display pics, and > more.http://clk.atdmt.com/UKM/go/157562755/direct/01/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
