摘要
It has been recognized that salinity variability in the tropical Pacific is closely related to the Interdecadal Pacific Oscillation(IPO).Here,we use model simulations from 1900 to 2017 to illustrate obvious asymmetries of salinity variability in the tropical Pacific during positive and negative IPO phases.The amplitude of salinity variability in the tropical Pacific during positive IPO phases is larger than that during negative IPO phases,with a more westward shift of a large Sea Surface Salinity(SSS)anomaly along the equator.Salinity budget analyses show that the asymmetry of salinity variability during positive and negative IPO phases is dominated by the difference in the surface forcing associated with the freshwater flux[FWF,precipitation(P)minus evaporation(E)],with a contribution of 40%–50%near the dateline on the equator.Moreover,the relationships between the salinity variability and its budget terms also show differences in their leadlag correlations during positive and negative IPO phases.These differences in salinity variability during different IPO phases produce asymmetric effects on seawater density which can reduce or enhance upper-ocean stratification.Therefore,the salinity effects may modulate the intensity of El Nino-Southern Oscillation(ENSO),resulting in an enhanced(reduced)El Nino but a reduced(enhanced)La Ni?a during positive(negative)IPO phases by 1.6℃psu^(-1)(1.3℃psu^(-1)),respectively.It is suggested that the asymmetry of salinity variability may be related to the recent change in ENSO amplitude associated with the IPO,which can help elucidate ENSO diversity.
基金
supported by the National Natural Science Foundation of China(NSFC
Grant No.42030410)
the Laoshan Laboratory(Grant No.LSKJ202202403)
the National Key Research and Development Program on Monitoring,Early Warning and Prevention of Major Natural Disaster(Grant Nos.2019YFC1510004,2020YFA0608902)
supported by the NSFC(Grant No.41976026)
supported by the Startup Foundation for Introducing Talent of NUIST。
