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

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） oscil- lation 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 mon- soon.