Fundamentals of climate: An article entitled “An Overview of the North Atlantic
ID: 116429 • Letter: F
Question
Fundamentals of climate:
An article entitled “An Overview of the North Atlantic Oscillation” by James W. Hurrell, Yochanan Kushnir, Geir Ottersen and Martin Visbeck (“The North Atlantic Oscillation: Climatic Significance and Environmental Impact. Geophysical Monograph 134. America Geophysical Union, 2003, p1-35). This article is available online.
(a) During the positive phase of the NAO, what happens to the surface temperature over (i) North America, (ii) Northern Europe and Eurasia, (iii) North Africa and the Middle East?
(b) During the positive phase of the NAO, what happens to the North Atlantic storm track?
(c) During the positive phase of the NAO, what happens to rainfall over (i) Greenland and the Canadian Arctic, (ii) central and southern Europe and the Mediterranean, (iii) Iceland, the British Isles and Scandinavia?
(d) What happens to all of these trends during the negative phase of the NAO?
Please answer these questions with as detailed as possible. Thank you for your help!
Explanation / Answer
(a)(i) During the positive phase of North Atlantic Oscillation (NAO), surface temperature in will be higher than normal in the continental United States as the strong westerlies move the cold arctic air to the North, hence north eastern parts of Canada will have a cooler winter.
(ii) Since the atmospheric pressure in the atlantic will be higher, strong westerlies carrying moisture will move towards Northern Europe and hence there will be high amount of precipitation. The mediterranean regions will experience a near drought, hence warmer temperatures.
(iii) Because of the above disturbances, strong winds will prevail in Northern Africa and Middle East which brings down the surface temperature, but it will be dry.
(b) Due to the shift of Azores high more south, the Atlantic storm is forced to move towards the Gulf of Mexico, if the Azores high moves northward, the North eastern USA will have a direct hit by a storm.
(c) (i)Rainfall in Greenland and Canadian Arctic will not be affected as the Westerlies will move the precipitation towards Europe.
(ii) In central and southern Europe and the Mediterranean, there will be a deficient rainfall.
(iii)Iceland and the British Isles will receive more than the normal rainfall as the westerlies bring in the moisture from the Atlantic.
(d) In the negative phase of th North Atlantic Oscillation, entire results will get reversed.
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