Synchronized Dipole-Like Oscillations’ Ocean-Atmosphere Interactions and Their Centennial-Scale Persistence

Monday, 15 December 2014
Elizabeth Reischmann, Jeseung Oh and Jose A Rial, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
Dipole phenomenon in ocean-atmospheric variability, such as the Indian Ocean Dipole and the El Niño Southern oscillation, which are also often called teleconnections, have long been recognized as important influences on local climate. This study presents a multi-faceted analysis of several newly identified sea surface temperature dipole locations, located via the traditional empirical orthogonal function analysis, as well as cross correlation analysis, of sea surface data from just over the last century. We begin with the analysis of two dipole modes ranged over the high latitudes in the Southern Hemisphere (located in the South Pacific and South Indian Ocean). These dipole modes have inter-annual periodicity as well as seasonal modes, with clear impacts on local, continental precipitation. Specifically, this study shows synchronization of sea surface temperature dipoles, their interactions with sea level pressure and winds, and makes steps towards understanding the dynamics of their connections via deconvolution of their respective climate signals. In order to study these effects, we define an index representing the time evolution of each dipole mode to follow the teleconnections of the sea surface temperature dipole modes with respect to other variables. This also allows for comparison with known, major, climate indices, allowing us to establish the effects of these oscillations as well as demonstrate the uniqueness of our new dipoles from these overarching influences. This study provides a more in depth understanding of teleconnection ocean-atmosphere dynamics, their effects on their local climates and distant climates, as well as their persistence over the previous century.