NAO- North Atlantic Oscillation

[KTtom]

The North Atlantic Oscillation is something you will hear about on the Model thread. It is basically a value given to the pressure differential between Greenland and the Azores. When the NAO is positive the pressure is a lot lower over Greenland than the Azores, this promotes a westerly mobile pattern over the UK. The chart below is a strongly positive NAO

http://www.wetterzentrale.de/archive/ra ... 050118.gif

A negative NAO has higher pressure over Greenland and lower pressure over the Azores, this stalls the Atlantic and promotes northerlies or easterlies.


http://www.wetterzentrale.de/archive/ra ... 101129.gif
...and some links for a professional explanation
http://www.cpc.ncep.noaa.gov/products/p ... ensm.shtml
http://www.cpc.ncep.noaa.gov/products/p ... ensm.shtml

http://www.nc-climate.ncsu.edu/climate/ ... s/NAO.html