Open AccessInvestigating possible links between the North Atlantic Oscillation and rainfall variability in northwestern France over the past 35 years
Author(s) -
Massei N.,
Durand A.,
Deloffre J.,
Dupont J. P.,
Valdes D.,
Laignel B.
Publication year - 2007
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd007000
Subject(s) - north atlantic oscillation , climatology , precipitation , atlantic multidecadal oscillation , teleconnection , environmental science , oscillation (cell signaling) , series (stratigraphy) , spectral analysis , wavelet , geology , el niño southern oscillation , geography , meteorology , physics , paleontology , quantum mechanics , artificial intelligence , biology , spectroscopy , computer science , genetics
In this paper, the temporal dynamics of precipitation in northwestern France in relation to the dominant climatic pattern in Europe were investigated. The general trends and the nonstationary behavior of the North Atlantic Oscillation (NAO) were described using fractal analysis and Fourier spectral and continuous wavelet analysis of a NAO index time series over the 1865–2004 period. The 44‐year and 8‐year multidecadal components showed a clear increasing power during the second half of the last century. The possible link between rainfall variability and the NAO was then investigated. The links between the NAO and rainfall were not as obvious, as NAO‐like components were not easily retrieved in the precipitation records: Relationships between the NAO and rainfall were very likely at certain timescales but were not systematically very obvious. For instance, the characteristic quasi‐biennal oscillation (QBO) of the NAO was barely detected in precipitation, but a ≈6‐year fluctuation beginning in the 90s was found to be statistically significant at a 95% confidence limit After investigating a possible link with the Southern Oscillation Index, the occurrence of this fluctuation in the beginning of the 90s could be related to the observed shift of the QBO toward slightly higher frequencies in the NAO time series. On the other hand, a modulation of the QBO by a ≈6‐year interannual fluctuation would suggest the existence of a ≈6‐year climate pattern that could affect precipitation and, to a lesser extent, the NAO. Cross‐wavelet analysis between the NAO and precipitation revealed a loss in correlation across the 1970–2005 period, which seemed to be the fact of a QBO‐like fluctuation. This loss of correlation was related to the above‐mentioned shift of the QBO and 6‐year rainfall interannual band since the 90s.