TITLE:
Influence of the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation on Global Temperature by Wavelet-Based Multifractal Analysis
AUTHORS:
Fumio Maruyama
KEYWORDS:
AMO, PDO, ENSO, Global Temperature, Wavelet, Multifractal
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.8,
August
16,
2019
ABSTRACT: Oceanic–atmospheric patterns, Atlantic Multidecadal
Oscillation (AMO) and Pacific Decadal Oscillation (PDO), and their respective
influence on the global warming hiatus were the main interests of this study. In general, a fractal property is observed in the time series of dynamics
of complex systems; hence, we investigated the relations among the AMO, PDO,
and El Niño-Southern Oscillation (ENSO) from the point of view
of multifractality, in which changes in fractality were
detected with multifractal analysis using wavelet transform. For the periods 1950-1976 and 1998-2012, global temperature increased little, with positive AMO and negative
PDO indices; subsequently, the rate of temperature increase weakened. Global temperature increased again in 1976, with the reversal of the AMO
and PDO indices from negative to positive. More specifically, AMO, PDO, and
Niño3.4 (ENSO index) exhibited fractality change from multifractality to
monofractality, providing them stability. Generally, the PDO was influenced largely by the ENSO. But, around 1960 and around 2000, whose
periods corresponded to hiatus periods in global warming, the influence of the
ENSO on the PDO was weak. In 1998, the AMO
increased and PDO decreased and global temperature increased little and the
multifractality of PDO, and Niño3.4 was weak, which corresponded to the change
from multifractality to monofractality in 1976. Wavelet analysis showed the
leads of PDO and Niño3.4 indices with respect to global temperature.
Consequently, the PDO and ENSO showed large influence on global temperature
and, further, on the global warming hiatus.