Phase-Locked Teleconnections and Their Climatic Impacts

Dipole behavior in ocean-atmosphere variability has been subject to extensive study due to their impacts on regional climates, such as that of the Indian Ocean Dipole. This study uses the results of a combined correlation coefficient and empirical orthogonal function analysis to study sea surface temperature anomaly dipoles with inter-annual periodicity, and explore seasonal variability. Previous work has shown that this dipole behavior has remained stable for at least the last century. Previous work has also shown that the polar climates also maintain a phase lock of 90° for the last 80,000 years. This stable, linear, phase relationship allows us to investigate possible physical mechanisms of connection via deconvolution. This method establishes a transfer function, which has been rigorously tested, demonstrating the usefulness of the method of spectral deconvolution for linearly related climate systems. Here we present different time scales of teleconnection behavior, their impacts on local climates, and discuss what methods of connection can allow them to remain sustained on a centennial or millennial scale. Multiple climate proxies are necessary to study these time scales and their impacts, from weekly satellite observations which have been extended to a centennial scale via multiple models, to annual or multi-annual resolution lake sediment and dendrochronology records with larger sampling rates and absolute dating uncertainty, to multi-millenial ice cores. Analysis techniques such as spectral deconvolution make use of the linear nature of these dipole connections to study the energy transfer functions and their physical implications. The longest scale results of this study use the synchronized nature of the polar climates on the millennial scale to suggest the predominant physical method of energy transfer between the polar signals.