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Natural climate change and variability
North Atlantic Oscillation
Remember that there are semi-permanent areas of high and low pressure. The North Atlantic Oscillation (NAO) occurs because of changes in the distribution of atmospheric mass between the subtropical high pressure system in the Atlantic Ocean and the Icelandic low pressure system. You can think of this as a shift in where the atmospheric mass is piling up. The NAO is also sometimes called the Northern Annular Mode (NAM - the NAM includes unusually high pressure in the north Pacific), or the Arctic Oscillation.
The NAO is important because it seems to explain a large portion of
week-to-week, month-to-month, and year-to-year changes in climate over portions
of the Northern Hemisphere. In other words, based on the phase of the NAO,
scientists can make a pretty accurate forecast for the coming winter - whether
it will be unusually warm, cold, wet, or dry.
There are two phases to the NAO - a positive and a negative phase. Let's take a look at both in the following pages.
Next page -> North Atlantic Oscillation, continued
Links and resources
North Atlantic Oscillation
Remember that there are semi-permanent areas of high and low pressure. The North Atlantic Oscillation (NAO) occurs because of changes in the distribution of atmospheric mass between the subtropical high pressure system in the Atlantic Ocean and the Icelandic low pressure system. You can think of this as a shift in where the atmospheric mass is piling up. The NAO is also sometimes called the Northern Annular Mode (NAM - the NAM includes unusually high pressure in the north Pacific), or the Arctic Oscillation.
The NAO is important because it seems to explain a large portion of
week-to-week, month-to-month, and year-to-year changes in climate over portions
of the Northern Hemisphere. In other words, based on the phase of the NAO,
scientists can make a pretty accurate forecast for the coming winter - whether
it will be unusually warm, cold, wet, or dry.There are two phases to the NAO - a positive and a negative phase. Let's take a look at both in the following pages.
Next page -> North Atlantic Oscillation, continued
Links and resources
