Geoscience Reference
In-Depth Information
(a) North Atlantic Oscillation (NAO), (Dec.
Mar. average)
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
1950
1960
1970
1980
1990
2000
2010
(b
) Arctic Oscillation (AO), (Dec.
Mar. average)
3
2
1
0
-1
-2
1950
1960
1970
1980
1990
2000
2010
Figure 3.9 (a) The NAO index and the (b) AO index averaged
over the Northern Hemisphere winter months (December,
January, February, and March).
4
2
0
-2
1900
1920
1940
1960
1980
2000
Figure 3.10 Monthly values of the PDO index (gray lines) with the smoothed
time series in black. Obtained with permission from the University of
Washington's Joint Institute for the Study of the Atmosphere and Oceans
(http://jisao.washington.edu/pdo/).
