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- The Matching Pursuit Transform does a better job in identifying the singularity in time series (e.g., Mobile NAO (NAOm) signal).
- In the time-frequency plane plot each wavelet coefficient occupies a box having a constant area ("Heisenberg uncertainty boxes"). There is significant "activity" at both fine and coarse scales.
- The "jumps" in the NAOm signal appear as fine-scale features (tall thin vertical boxes). The fine-scale features are well localized in time, but poorly localized in frequency. The most significant "jumps" occurred in 1961, late 1962, late 1972, and 1986. Wider "jumps" for periods greater than 1.3 years occurred in 1978-79, 1983-84, and 1998-99. Also, note the much wider "jumps" occurring in 1990-92 for periods greater than 3 years.
- The "smooth" part of the NAOm signal appears as a coarse-scale feature (relatively flat wide boxes) which are poorly localized in time. However, coarse-scale features are generally well localized in frequency. Examples: late 1984-89 for periods greater than 5 years, and 1995-2000 centered at 3.5 years.
* Conclusion:
- The changing nature of the NAOm signal is reflected in the time-frequency plot. Coarser-scale features in the lower frequency range have been more dominant in recent years and finer-scale features have been more dominant in the 1960s-1970s.
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Relationships between winter air temperature over south-western Europe and atmospheric circulation
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A) An index of the 60-70 year Atlantic Multidecadal Oscillation (AMO) is shown with its principal warm and cool phases during the 20th century. For each phase a 30 year period is identified that is used to correlate tropical Pacific SST variability with U.S. Rainfall. B) Correlation of the boreal winter NINO 3.4 SST index with averaged U.S. Rainfall for January-February-March, in the positive phase period (1930-59). C) As in (B), but for the negative phase period (1965-1994).
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Study of Frequency Variability of Winter Precipitation over the South-Western Europe and its Relationships with Teleconnection Indices
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Weakening and strengthening of the North Atlantic Gyre Circulation associated with the NAO
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Author: Jung and Hilmer (IfM-Kiel)
Shift of the Centers of Interannual NAO Variability
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Author: K. Drinkwater (BIO)
The Impact of the NAO on the Growth of Atlantic Cod off Labrador and Newfoundland.
The grow of northern cod, as defined by the weight gain between ages 2 and 5, is inversely related to the NAO index. The index is the average over the 3 years the cod is growing. A high index, which produces cold ocean temperatures, strong winds and lots of ice off Labrador and Newfoundland, results in low growth. The pictures of the cod show the relative size of 5-year old fish under maximum and minimum NAO conditions.
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Author: D.P. Stephenson (BIO)
NAO and the sexlife of Scandinavian ungulates
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