Combined effects of the Pacific Decadal Oscillation and El Niño-Southern Oscillation on global land dry-wet changes.

Shanshan Wang,Jianping Huang,Yuping Guan,Yongli He

doi:10.1038/srep06651

Abstract

The effects of natural variability, especially El Niño-Southern Oscillation (ENSO) effects, have been the focus of several recent studies on the change of drought patterns with climate change. The interannual relationship between ENSO and the global climate is not stationary and can be modulated by the Pacific Decadal Oscillation (PDO). However, the global land distribution of the dry–wet changes associated with the combination of ENSO and the PDO remains unclear. In the present study, this is investigated using a revised Palmer Drought Severity Index dataset (sc_PDSI_pm). We find that the effect of ENSO on dry–wet changes varies with the PDO phase. When in phase with the PDO, ENSO-induced dry–wet changes are magnified with respect to the canonical pattern. When out of phase, these dry–wet variations weaken or even disappear. This remarkable contrast in ENSO's influence between the two phases of the PDO highlights exciting new avenues for obtaining improved global climate predictions. In recent decades, the PDO has turned negative with more La Niña events, implying more rain and flooding over land. La Niña-induced wet areas become wetter and the dry areas become drier and smaller due to the effects of the cold PDO phase.

Highlights

Combined effects of the Pacific Decadal Oscillation and El Nino-Southern Oscillation on Global Land Dry–Wet Changes
We find that the effect of El Nino-Southern Oscillation (ENSO) on dry–wet changes varies with the Pacific Decadal Oscillation (PDO) phase
Sub-composites with respect to the PDO phase www.nature.com/scientificreports reveal that the global El Nino-induced dry–wet changes are determined primarily by El Nino winters that occur during the warm phase of the PDO

Summary

Introduction

Combined effects of the Pacific Decadal Oscillation and El Nino-Southern Oscillation on Global Land Dry–Wet Changes. The effects of natural variability, especially El Nino-Southern Oscillation (ENSO) effects, have been the focus of several recent studies on the change of drought patterns with climate change. How patterns of drought are changing as the climate changes has been the focus of several recent studies, but the answer remains unclear. Many studies have revealed that the PDO exerts a modulating effect on ENSO teleconnections over many parts of the world, such as the US9–12, South America[13], Mexico[14], Australia[15], and East Asia[16,17]; the combined effect of ENSO and the PDO on global dry–wet changes remains unclear. Because the influence of the tropical Pacific on climate is most pronounced in the boreal winter[18,19,20], only December, January and February (DJF) are discussed

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Conclusion