Open AccessOn long-term evolution of seasonal precipitation in southwestern Europe
Author(s) -
Francisco Valero,
F. J. Doblas,
Juan F. González
Publication year - 1996
Publication title -
annales geophysicae
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.522
H-Index - 93
eISSN - 1432-0576
pISSN - 0992-7689
DOI - 10.1007/s00585-996-0976-8
Subject(s) - precipitation , climatology , amplitude , annual cycle , environmental science , mesoscale meteorology , mediterranean climate , atmospheric circulation , teleconnection , geology , atmospheric sciences , meteorology , geography , el niño southern oscillation , physics , archaeology , quantum mechanics
Annual cycles in long time series ofprecipitation from sixteen southwest European observatories have been analysedusing complex demodulation. The stations have been clustered into two distinctregions and a hybrid one. They are referred to as the southwestern Europeprecipitation Atlantic regime (SEPAR) and the southwestern Europe precipitationMediterranean regime (SEPMER), with the hybrid regime referred to in terms ofthe mean amplitude ratios between semiannual and annual rainfall components.Some evidence of linking between seasonal cycle harmonic amplitudes and thezonal circulation has been found for SEPAR stations and a more obscuredrelationship for the SEPMER region. Within the SEPAR region the strength of therelationship is diminished towards the north. A trend analysis of the amplitudesagainst time since 1920 has also been carried out and the results reveal adivergent pattern in trends between annual and semiannual component amplitudesfor the SEPAR region. In fact, both an increasing annual-amplitude trend and adecreasing semiannual-amplitude trend are observed, in each case statisticallysignificant. The fact that the seasonal cycle variability of rainfall insouthwestern Europe becomes more sensitive southwards to changes in atmosphericzonal circulation over the North Atlantic might, in our opinion, be related tothe swing of the circumpolar vortex