SEASONAL PERSISTENCE OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS RELATIONSHIP WITH THE SURFACE HEAT FLUX ANOMALY

This paper investigates the interannual variation of the West Pacific Subtropical High(WPSH) intensity based on the data compiled by the Chinese National Climate Center.Monthly reanalysis data from National Centers for Environmental Prediction and National Center for Atmospheric Research(NCEP/NCAR) are also used to study the lead-lag relationship between WPSH intensity and surface heat flux anomalies.The three major findings are as follows:First,WPSH intensity presents good seasonal persistence,especially from winter to the ensuing summer.Persistence is more significant after 1977,especially from spring to summer,and from summer to autumn;persistence of anticyclonic anomalies are significantly better than cyclonic anomalies.Second,surface heat flux tends to present opposite anomalous patterns between the strong and weak years of the WPSH intensity,which is especially valid at the latent heat flux over the ocean.Simultaneous correlations between surface heat flux and WPSH intensity in each of the seasons are marked by similar key areas.Finally,surface heat flux from the preceding winter of a strong summer WPSH is quite similar to strong spring WPSH,but the positive anomalies over the northwest Pacific and south of Japan are notably stronger.The situations in the weak years are similar except for those over the northwest Pacific:winter surface heat flux shows negative anomalies for a weak spring WPSH,but positive anomalies for a weak summer WPSH.It is suggested that surface heat flux in the previous winter plays an important role in maintaining the WPSH intensity in the ensuing spring and summer.