The multi-scale variability of sea surface height in the northeastern South China Sea

The wavelet transformation methods were applied to 8 a(1993~2000)TOPEX/Poseidon data set to investigate the multiple time-scale variability of sea surface height(SSH)in the northeastern South China Sea(SCS). Analysis results indicate that SSH variation mainly subjects to influences from three factors of different time-scale. Among them,the seasonal variation(V_a),with period range from 0.60 to 1.20 a,appears to be the strongest, which mainly relates to seasonal cycling of SSH.Secondly,the variation(V₂₅),with period range from 0.17 to 0.45 a(i.e.,of 2~5 months period),mainly relates to SSH variation caused by mesoscale phenomena.Arelatively weak factor is the interannual variation(V_i)with period range from 1.50 to 5.00 a,w hich mainly associates with SSH changes of El Niño events.Analyses also show that,from eight years mean distribution,high variation areas of energy variance V₂₅ appears mainly to the west of Luzon Strait with energy maximums in 1995,1996 and 1999.Areas of high V_a appear in the sea area northwest off Luzon Island show a energy peak in 1995.And high variation areas of inter annual variance V_i are located to southwest of Taiwan Island which reaches energy maximum during the 1997/1998 El Niño event period.