Arctic Oscillation

Arctic Oscillation

Have you ever noticed how, occasionally, a special phrase pops into your life and you find yourself looking for the chance to casually toss it into a conversation?  Arctic oscillation is one such phrase.  So, despite the fact that strange weather patterns have been mentioned perhaps too often recently in this blog, it’s hard to resist at least one more shot at this winter’s seesawing temperatures, which we have learned are due to — wait for it — Arctic oscillation.           

So, how do we oscillate from winter to spring and back again?

A recent report by Murat Yukselir in the Globe and Mail, using sources as diverse as NASA, the University of Ottawa, and Environment Canada, explains that the lack of snow in Canada this winter is due to changes in the behaviour of the polar jet stream. The polar jet stream usually lies in the upper latitudes of North America, while the sub-tropical jet stream is further south. Jet streams are usually wavy, forming peaks of warm weather further north and troughs of colder weather further south. In the positive phase of Arctic oscillation, the waves in the polar jet stream have straightened somewhat , reducing the size of the peaks and troughs. That tightening traps the cold Arctic air closer to the North Pole and leaves the rest of Canada under the warmer air mass.  Mr. Yukselir’s report is bolstered by a chart showing a significant reduction in the number of days below freezing (O° Celsius) for selected cities in Canada this winter ( up to January 24) as compared to the same period last year.

It would seem that Nova Scotia black ducks
are unperturbed by the oscillations. They simply move in and out of the cove according to the amount of ice coverage, feeding on plant life along the shore.

Earlier heavy snowfalls have all been rained out of existence, so local gardeners who were counting on a good snow cover to protect their plants are wondering what the damage will be when Spring makes its official appearance.  Holly berries and other shrubs have provided particularly good grazing for the deer this winter because of easy access.  One garden in which they are denied access is that of Niki Jabbour, whose book The Year-Round Vegetable Gardener is now available in gardening centres in the Maritimes. More information on the book is available on her website:  www.yearroundveggiegardener.blogspot.com

Leave a Reply

Your email address will not be published.