Multi-scale features of the co-variability between global sea surface temperature anomalies and daily extreme rainfall in Argentina

Abstract

The goal of this study is to provide a better understanding of the trends and dominant oscillations characterizing the co-variability between global sea surface temperature (SST) anomalies and daily extreme rainfall in Argentina. A singular value decomposition was performed between daily extreme rainfall monthly index in Argentina and global SST without removing the trends. The three leading modes explain 70.5% of the co-variability, while the two leading modes explain more than 66% of the variability. The two leading modes exhibit significant variability on inter-annual timescales related to tropical Pacific and Indian oceans, and specifically with El Niño–Southern Oscillation and the Indian Ocean Dipole. On decadal timescales, the leading mode activity is related to the Pacific Decadal Oscillation, whereas the second leading mode is associated with the Atlantic Multi-decadal Oscillation (AMO). The third leading mode show co-variability between the SST of the tropical Atlantic and the Indian ocean and extreme rainfall in the eastern-centre of Argentina; this mode distinguishes phases of AMO. In addition, the two leading modes show positive trends, being largely non-linear for leading one. The fact that extreme rainfall changes in Argentina observed in the last decades, are significantly influenced by the combination of the multi-decadal variability and long-term trends associated with the tropical oceans, is valuable knowledge to assess them in the future.