Onset of the 1998 summer monsoon in the south china sea-evidence from satellite microwave scatterometer

Weekly averaged winds observed by satellite microwave scatterometer on board ERS-2 are analyzed to reveal the onset process of the 1998 South China Sea (SCS) summer monsoon.The seatterometer data sets are firstly validated by field wind observation from a buoy located at 114.41E, 12.98N during the same period.Results of the analysis suggest that in 1998, onset of the SCS summer monsoon started in the third week of May (May 18-May 2zi), and the summer monsoon was fully established in late May.Onset of the 1998 summer monsoon is associated with the eastward withdrawal of the North Pacific trade wind system, the development of Indian monsoon, and the occurrence of cross equatorial airflow.However, the SCS summer monsoon also shows its own independence in the mature phase.Local ocean-atmosphere and land-atmosphere interactions may also influence the onset and development of the SCS summer monsoon.