Interannual variability of the 10-25- and 30-60-day variation over the South China Sea during boreal summer

[1] The interannual variability (IAV) of the intraseasonal variation (ISV) over the South China Sea (SCS) was investigated, focusing on the relationship between the 10-25- and 30-60- day variation. Both ISV activities over the SCS had larger IAV than those of the Bay of Bengal and Arabian Sea. The 10-25- ( 30-60-) day variation was relatively active when the 30-60- ( 10-25-) day variation was suppressed in June, July and September. The IAV of the ISV during early summer ( June-July) was related to the IAV of the SCS monsoon onset. A late ( early) onset was accompanied by active 10-25- ( 30-60-) day variation. The IAV of the ISV could be divided into early and late summer ( September), because there was little persistence between these two periods. Moreover, large-scale circulation anomalies associated with the IAV had different spatial structures in these two periods.