Tuesday, February 22, 2011


The Quasi-Biennial Oscillation (QBO) is changes in equatorial zonal wind between easterlies and westerlies in the tropical stratosphere. (Defined partially From Wikipedia, the free encyclopedia.) The map above from NOAA's Climate Prediction Center (CPC) demonstrates Two Phases of the QBO, which are termed East QBO & West QBO. The relationship between oscillating wind regimes and High Latitude Blocking is significant, due to changes between the easterlies & westerlies. The Easterly Phase QBO encourages high latitude blocking because westerly trade winds are weaker, while the Westerly Phase is not supportive of long-term blocking due to stronger westerlies. On February 28 to March 1, 2010 a major longwave pattern change took place over the Northern Hemisphere. This major change was also associated with a change from an East QBO to West QBO, which resulted in a complete different summer pattern during 2010 in contrast to 2009. The QBO has primarily been in a Westerly phase since the beginning of last March, which in return discourages a long-term Negative AO & NAO (associated with a classic old-fashioned March in New England.)        

1 comment: