A review of short-term climate variability mechanisms

Abstract

Climate varies from seasonal to centennial time scales. In the last two decades progress has been made to better understand several aspects of short-term variability of the Earth’s climate system. Tropical Pacific is dominated by a single mode of interannual climate variability, which reflects the coupling of the Ocean and the atmosphere and is expressed by the El Niño/Southern Oscillation (ENSO) phenomenon. The Pacific climate contains another mode of variability similar to the ENSO, but varying on a decadal scale, the Pacific Decadal Oscillation (PDO) mode. Variations of the sea surface temperature (SST) in the Tropical Atlantic also play an important role in modulating the climate variability. The SST variability in this basin might be explained by at least five modes: separate modes in the Tropical North Atlantic and Tropical South Atlantic, equatorial mode, dipole mode and cross-equatorial SST anomaly gradient mode. Among these modes, the equatorial mode contains strong interannual variability, while the dipole and the cross-equatorial SST anomaly gradient modes contain strong decadal variability. Some aspects of the climate variability, with emphasis on the ENSO, PDO modes in the Pacific and the Atlantic SST modes on the interannual and decadal time scales, are discussed in the present paper.