A new PJ index is introduced by using the singular value decomposition(SVD) method at the 500 hPa height field in summer in East Asia as well as in precipitation field near the Philippines.This time series/index can clearly reflect the PJ interannual and interdecadal variations,which were demonstrated by the 500 hPa height switching from "cyclone,anticyclone,cyclone" to "anticyclone,cyclone,anticyclone" in the late 1970s.This study also shows that the interannual variation of the PJ index is closely related to the El Niño Southern Oscillation(ENSO) event.El Niño teleconnection makes the Sea surface temperature(SST) in tropical Indian Ocean(TIO) increase like a battery charging a capacitor,and the increased temperature leads to the formation of abnormal anticyclones near the Philippine Sea.In addition,ENSO events also stimulate the PJ teleconnection pattern along the coast of East Asia.Moreover,the interdecadal variation of PJ patterns is related to the continuous increasing TIO SST.Many researchers have proposed that SST anomalies near the Philippine Sea result in anomalous convection and stimulate the PJ teleconnection pattern along the coast of East Asia.However,we have concluded that variations of SST in this area are not the reason for the interannual and interdecadal variations of the PJ pattern.Instead,these variations result from the TIO SST anomalies.The SST anomalies over the Philippine Sea are caused by the NW Pacific anticyclone,thus the radiation increases(decreases),the evaporation decreases(increases),the thermocline deepens(shoals) and the SST becomes warmer(colder).The increased SST in this area corresponds to weakened convection.Furthermore,numerical simulations by using the atmospheric circulation model ECHAM5.4(European Centre Hamburg Model5.4) show that when the TIO SST increases,anticyclones are produced near the Philippine Sea and stimulate the "anticyclone,cyclone,anticyclone" PJ teleconnection pattern along the coast of East Asia.