Relative roles of equatorial central Pacific and western North Pacific precipitation anomalies in ENSO teleconnection over the North Pacific

Abstract

It is shown here that the teleconnections of El Nino-Southern Oscillation (ENSO) are contributed by two anomalous precipitation forcings in the equatorial central Pacific (CP; 160 degrees E-120 degrees W, 5 degrees S-5 degrees N) and western North Pacific (WNP; 110 degrees E-150 degrees E, 0 degrees N-20 degrees N). The positive CP precipitation anomalies induce a prevailing cyclonic flow over the North Pacific (120 degrees E-110 degrees W, 20 degrees N-70 degrees N), whereas the negative WNP precipitation forcing tends to induce anticyclonic anomalies over the Kuroshio extension region and North Pacific. It is demonstrated that the equatorial CP and WNP precipitation anomalies play relative roles in generating atmospheric teleconnections over the North Pacific, which can be determined by the competing responses to the CP and WNP precipitation anomalies. The reconstructed teleconnection patterns based on only the two tropical forcings capture the majority of the subseasonal evolution of the ENSO teleconnection. In addition, we find that the diversity of inter-ENSO events in the atmospheric teleconnection can be better-explained by considering the relative roles of the CP and WNP precipitation anomalies.