Seasons

You’ve already learned that El Nino and La Nina events are caused by changes in the wind patterns over the Equatorial Pacific and that these changes can have far reaching impacts around the globe.

The Pacific Decadal Oscillation (PDO) is a pattern of warm phases and cool phases in the North Pacific Ocean that last anywhere from 10 to 40 years. The phases are associated with changes in sea surface temperatures (SST) and can affect marine ecosystems and even change the path of the jet stream.

The North Atlantic Oscillation (NAO) is a seesaw atmospheric pattern between persistent high and low pressures over portions of the North Atlantic Ocean. This pattern governs the position and strength of the North Atlantic storm tracks which affects weather conditions in Europe and the Eastern portions of North America including temperature, pressure, prevailing winds, and even sea-surface temperature anomalies, strength of the Gulf Stream, atmosphere wave structure and distribution of sea ice and icebergs. The ‘seesaw’ swings can last weeks, months, years or decades and can be unpredictable and sudden.