The E1 Nifio-Southern Oscillation (ENSO) is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical ...The E1 Nifio-Southern Oscillation (ENSO) is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical Pacific. Freshwater flux (FWF) is another the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model (HCM) to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity (SSS) and buoyancy flux (QB) in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual Qs variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nifia and enhancing warming during E1 Nifio, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.展开更多
By utilizing multiple datasets from various sources available for the last 100 years, the existence for the interdecadal change of the winter sea surface temperature(SST) variability in the Kuroshio Extension(KE) ...By utilizing multiple datasets from various sources available for the last 100 years, the existence for the interdecadal change of the winter sea surface temperature(SST) variability in the Kuroshio Extension(KE) region is investigated. And its linkage with the Aleutian Low(AL) activity changes is also discussed. The results find that the KE SST variability exhibits the significant ~6 a and ~10 a oscillations with obvious interdecadal change. The ~6 a oscillation is mainly detected during 1930–1950, which is largely impacted by the anomalous surface heat flux forcing and Ekman heat transport associated with the AL intensity variation. The ~10 a oscillation is most evident after the 1980s, which is predominantly triggered by the AL north-south shift through the bridge of oceanic Rossby waves.展开更多
The change of sea surface temperature(SST) in the southern Indian Ocean(SIO) during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show tha...The change of sea surface temperature(SST) in the southern Indian Ocean(SIO) during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show that a thermal regime shift in SIO during the 1960 s, which is not caught enough attentions, has been of equal magnitude to the linear warming since 1970. Empirical Orthogonal Function(EOF) analyses reveal that a thermal shift is combined with atmospheric changes such as the weakening of westerly during the period of 1960–1967. Inner dynamic connections can be defined that when the westerly winds turn weak, the anticyclonic wind circulation between westerly winds and the trade winds decreases, which further reduces the SST to a negative peak in this period. It is noted that the shifts in the 1960 s are also evident for Southern Hemisphere. For example, subtropical high and the entire westerly winds belt at high latitudes both change dramatically in the 1960 s. This large-scaled process maybe link to the change of southern annular mode(SAM).展开更多
基金supported in part by NSF Grant(ATM-0727668and AGS-1061998)NOAA Grant(NA08OAR4310885)+3 种基金NASA Grants(NNX08AI74G,NNX08AI76G,and NNX09AF41G)F.Zheng is supported by the National Basic Research Program of China(GrantNos.2012CB417404and2012CB955202)the Natural Science Foundation of China(Grant No.41075064)Pei is additionally supported by China Scholarship Coun-cil(CSC) with the Ocean University of China,Qingdao,China
文摘The E1 Nifio-Southern Oscillation (ENSO) is emphasized the roles of wind stress and heat flux environmental forcing to the ocean; its effect and modulated by many factors; most previous studies have in the tropical Pacific. Freshwater flux (FWF) is another the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model (HCM) to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity (SSS) and buoyancy flux (QB) in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual Qs variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nifia and enhancing warming during E1 Nifio, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.
基金The National Basic Research Program(973 program)of China under contract No.2013CB956203the National Natural Science Foundation of China under contract No.41375063
文摘By utilizing multiple datasets from various sources available for the last 100 years, the existence for the interdecadal change of the winter sea surface temperature(SST) variability in the Kuroshio Extension(KE) region is investigated. And its linkage with the Aleutian Low(AL) activity changes is also discussed. The results find that the KE SST variability exhibits the significant ~6 a and ~10 a oscillations with obvious interdecadal change. The ~6 a oscillation is mainly detected during 1930–1950, which is largely impacted by the anomalous surface heat flux forcing and Ekman heat transport associated with the AL intensity variation. The ~10 a oscillation is most evident after the 1980s, which is predominantly triggered by the AL north-south shift through the bridge of oceanic Rossby waves.
基金The National Natural Science Foundation of China for Distinguished Young Scholars and Innovative Research Groups under contract Nos 41525019 and 41521005the Project of the State Oceanic Administration of China for Global Climate Change under contract No.GASI-IPOVAI-02the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘The change of sea surface temperature(SST) in the southern Indian Ocean(SIO) during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show that a thermal regime shift in SIO during the 1960 s, which is not caught enough attentions, has been of equal magnitude to the linear warming since 1970. Empirical Orthogonal Function(EOF) analyses reveal that a thermal shift is combined with atmospheric changes such as the weakening of westerly during the period of 1960–1967. Inner dynamic connections can be defined that when the westerly winds turn weak, the anticyclonic wind circulation between westerly winds and the trade winds decreases, which further reduces the SST to a negative peak in this period. It is noted that the shifts in the 1960 s are also evident for Southern Hemisphere. For example, subtropical high and the entire westerly winds belt at high latitudes both change dramatically in the 1960 s. This large-scaled process maybe link to the change of southern annular mode(SAM).