By analyzing the variability of global SST （sea surface temperature） anomalies, we propose a unified Nifio index using the surface thermal centroid anomaly of the region along the Pacific equator embraced by the 0.7...By analyzing the variability of global SST （sea surface temperature） anomalies, we propose a unified Nifio index using the surface thermal centroid anomaly of the region along the Pacific equator embraced by the 0.7~C contour line of the standard deviation of the SST anomalies and try to unify the traditional Nifio regions into a single entity. The unified Nifio region covers almost all of the traditional Nifio regions. The anomaly time series of the averaged SST over this region are closely correlated to historical Nifio indices. The anomaly time series of the zonal and meridional thermal centroid have close correlation with historical TNI （Trans-Nifio index） indices, showing differences among E1 Nifio （La Nifia） events. The meridional centroid anomaly suggests that areas of maximum temperature anomaly are moving meridionally （although slightly） with synchronous zonal movement. The zonal centroid anomalies of the unified Nifio region are found helpful in the classification of the Eastern Pacific （EP）/Central Pacific （CP） types of E1 Nifio events. More importantly, the zonal centroid anomaly shows that warm areas might move during a single warming/cooling phase. All the current Nifio indices can be well represented by a simple linear combination of unified Nifio indices, which suggests that the thermal anomaly （SSTA） and thermal centroid location anomaly of the unified Nifio region would yield a more complete image of each E1 Nifio/ La Nina event.展开更多
Numerous published results have showr the importance of the Wcstern Pacific Warm Pool （WPWP）surface centroid movement in ENSO-（EI Nino/Southcrn Oscillation）rclated studies .Howcver,some rccent research conclusions...Numerous published results have showr the importance of the Wcstern Pacific Warm Pool （WPWP）surface centroid movement in ENSO-（EI Nino/Southcrn Oscillation）rclated studies .Howcver,some rccent research conclusions make it necessary to clarify the differenccs of the currently exicing two types of WPWP surface centroid：the geometric centroid and the thermal （heat）centrold.This study analyzes the physical backgrounds of the two typcs of centroid and points out their differenccs.which suggest that different types of ccntroid may scrve different study purposes.This study also shows that the ‘geometric center’of WPWP.actually a close approximation to the mass ccntroid,is more related to the Nino-3 region sca surfacc temperaturc（SST）ancmaly and can also be regarded as an important indicator of ENSO events.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(Nos.2012CB957704,2009CB723903)the National Natural Science Foundation of China(Nos.40506035,40876005)
文摘By analyzing the variability of global SST （sea surface temperature） anomalies, we propose a unified Nifio index using the surface thermal centroid anomaly of the region along the Pacific equator embraced by the 0.7~C contour line of the standard deviation of the SST anomalies and try to unify the traditional Nifio regions into a single entity. The unified Nifio region covers almost all of the traditional Nifio regions. The anomaly time series of the averaged SST over this region are closely correlated to historical Nifio indices. The anomaly time series of the zonal and meridional thermal centroid have close correlation with historical TNI （Trans-Nifio index） indices, showing differences among E1 Nifio （La Nifia） events. The meridional centroid anomaly suggests that areas of maximum temperature anomaly are moving meridionally （although slightly） with synchronous zonal movement. The zonal centroid anomalies of the unified Nifio region are found helpful in the classification of the Eastern Pacific （EP）/Central Pacific （CP） types of E1 Nifio events. More importantly, the zonal centroid anomaly shows that warm areas might move during a single warming/cooling phase. All the current Nifio indices can be well represented by a simple linear combination of unified Nifio indices, which suggests that the thermal anomaly （SSTA） and thermal centroid location anomaly of the unified Nifio region would yield a more complete image of each E1 Nifio/ La Nina event.
基金This study has been supported by the Doctoral Startup Foundation of 0cean University of China(2003)partly by the Natural Science Foundation of China(No.40506035).The author is thankful to the NCDC for the SST data.The author also thanks the reviewers for their very valuable suggestions.
文摘Numerous published results have showr the importance of the Wcstern Pacific Warm Pool （WPWP）surface centroid movement in ENSO-（EI Nino/Southcrn Oscillation）rclated studies .Howcver,some rccent research conclusions make it necessary to clarify the differenccs of the currently exicing two types of WPWP surface centroid：the geometric centroid and the thermal （heat）centrold.This study analyzes the physical backgrounds of the two typcs of centroid and points out their differenccs.which suggest that different types of ccntroid may scrve different study purposes.This study also shows that the ‘geometric center’of WPWP.actually a close approximation to the mass ccntroid,is more related to the Nino-3 region sca surfacc temperaturc（SST）ancmaly and can also be regarded as an important indicator of ENSO events.
