Long-term variability of central Andes precipitation in the IPSL- CM6A-LR model: origin and causes

BEYREM JEBRI; VALÉRIE DAUX; MYRIAM KHODRI; ELIZABETH B. NARANJO TAMAYO; JULIÁN VILLAMAYOR; JUAN A RIVERA

Munich

Congreso; EGU General Assembly 2020; 2020

The central Andes have undergone a drying trend over the last decades with adversesocioeconomic effects throughout the south of Argentina and Chile. The long-term precipitationvariability in this region has been associated with modes of sea surface temperature (SST) andatmospheric circulation variability acting at decadal-to-multidecadal timescales, such as theInterdecadal Pacific Oscillation and the Southern Annular Mode. More recently, the drying longterm trend of precipitation in central Andes has also been linked to a poleward expansion of theHadley Cell (HC) in the Southern Hemisphere over the last decades. In previous works severalpossible causes of the HC expansion have been proposed, involving both external forcing (e.g.,greenhouse gases and ozone depletion effects) and internal climate variability (e.g., SST andatmospheric modes).In this work the origin and the causes of the central Andes precipitation variability at decadal-tolonger time scales are studied. For this purpose, the main modes of climate variability thatmodulate the central Andes precipitation are first identified. Then the changes of these modes andtheir influence on precipitation are attributed to different factors of external forcing or to internalclimate variability. For this analysis large ensembles of different climate simulations and detectionand-attribution experiments performed with the IPSL-CM6A-LR model are used.