The Oscillation between Tropical Indian Ocean and North Pacific: Evidence and Possible Impact on Winter Climate in China

Abstract

This paper provides evidence that the variation of boreal winter sea level pressure (SLP) over the North Pacific is out-of-phase with SLP fluctuation over the tropical Indian Ocean on both the interdecadal and interannual time scales. Subsequently, a SLP between tropical Indian Ocean and North Pacific (TIO-NP) oscillation index is defined to indicate the variation of such out-of-phase fluctuation. Moreover, the simultaneous surface air temperature and precipitation anomalies in China are closely related to TIO-NP oscillations. Below-normal surface air temperature anomalies in the northern and the eastern part of China, and less rainfall in southern China, correspond to positive TIO-NP oscillation phase with negative SLP anomalies in tropical Indian Ocean and positive anomalies in North Pacific. The TIO-NP oscillation affects China’s winter climate anomalies, possibly through modulating the northeast East Asia winter monsoon.