How is NAO calculated?
How is NAO calculated?
The standard NAO Index is calculated by taking the difference between normalized surface pressure anomaly from a 30 years mean of a northern and a southern station (Equation 1).
Is The NAO positive or negative?
The NAO is in a positive phase when both the sub-polar low and the subtropical high are stronger than average. During positive NAO phases, the increased difference in pressure between the two regions results in a stronger Atlantic jet stream and a northward shift of the storm track.
What is NAO meteorology?
North Atlantic Oscillation (NAO), an irregular fluctuation of atmospheric pressure over the North Atlantic Ocean that has a strong effect on winter weather in Europe, Greenland, northeastern North America, North Africa, and northern Asia.
What happens during a weakening of the NAO?
Simply put the negative NAO creates an “atmospheric road block.” The westerly winds weaken, resulting in limited upper air flow over the entire North Atlantic extending all the way to the US East Coast. The reduced flow also keeps cold air locked into the eastern US.
What makes Azores high?
The ultimate cause is probably related to the inherent distribution of continents and oceans. Large east-west circulations exist in heating between subtropical continents and oceans.
Where is the Azores high today?
North East Atlantic Ocean
The current position of AZORES HIGH is at North East Atlantic Ocean (coordinates 37.12148 N / 8.52842 W) reported 383 days ago by AIS.
What does a positive NAO index mean?
The positive NAO phase represents a stronger than usual difference in pressure between the two regions. Winds from the west dominate, bringing with them warm air, while the position of the jet stream enables stronger and more frequent storms to travel across the Atlantic.
What is a West based NAO?
The North Atlantic Oscillation (NAO) has two phases: Positive and Negative. The counterpart of the east based NAO is the ‘West Based’ NAO. As you may imagine, west based means that the strongest part of the high pressure system is now to the west of Greenland, as annotated for above.
What is NAO region?
The NAO is the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale seesaw in atmospheric mass between the subtropical high and the polar low.
What causes Icelandic low?
In winter the ocean is considerably warmer than the continents, and this difference is responsible for the location of the Icelandic low, which dominates the wind circulation over the North Atlantic (see North Atlantic Oscillation).
What influences the NAO?
North Atlantic Oscillation. Changes in local weather patterns such as temperature, rainfall and wind strength/direction are strongly influenced by changing local pressure patterns.
