DOI: 10.1175/JCLI-D-13-00438.1
Scopus记录号: 2-s2.0-84897012735
论文题名: Assessing the twenty-first-century shift in enso variability in terms of the bjerknes stability index
作者: Lübbecke J.F. ; Mcphaden M.J.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2014
卷: 27, 期: 7 起始页码: 2577
结束页码: 2587
语种: 英语
Scopus关键词: Stream flow
; Wind stress
; Damped systems
; Decadal change
; Eastern equatorial Pacific
; Eastern pacific
; Equatorial Pacific
; Stability indices
; Stress response
; Walker circulation
; Oceanography
; El Nino-Southern Oscillation
; index method
; sea surface temperature
; temperature anomaly
; thermocline
; twenty first century
; Walker circulation
; wind stress
; zonal wind
; Pacific Ocean
; Pacific Ocean (Central)
; Pacific Ocean (Equatorial)
英文摘要: A decadal change in the character of ENSO was observed around year 2000 toward weaker-amplitude, higher-frequency events with an increased occurrence of central Pacific El Niños. Here these changes are assessed in terms of the Bjerknes stability index (BJ index), which is a measure of the growth rate of ENSOrelated SST anomalies. The individual terms of the index are calculated from ocean reanalysis products separately for the time periods 1980-99 and 2000-10. The spread between the products is large, but they show a robust weakening of the thermocline feedback due to a reduced thermocline slope response to anomalous zonal wind stress as well as a weakened wind stress response to eastern equatorial Pacific SST anomalies. These changes are consistent with changes in the background state of the tropical Pacific: cooler mean SST in the eastern and central equatorial Pacific results in reduced convection there together with a westward shift in the ascending branch of the Walker circulation. This shift leads to a weakening in the relationship between eastern Pacific SST and longitudinally averaged equatorial zonal wind stress. Also, despite a steeper mean thermocline slope in the more recent period, the thermocline slope response to wind stress anomalies weakened due to a smaller zonal wind fetch that results from ENSO-related wind anomalies being more confined to the western basin. As a result, the total BJ index is more negative, corresponding to a more strongly damped system in the past decade compared to the 1980s and 1990s. © 2014 American Meteorological Society. 资助项目: NOAA, National Oceanic and Atmospheric Administration
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/51390
Appears in Collections: 气候变化事实与影响
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作者单位: NOAA/Pacific Marine Environmental Laboratory, Seattle, WA, United States
Recommended Citation:
Lübbecke J.F.,Mcphaden M.J.. Assessing the twenty-first-century shift in enso variability in terms of the bjerknes stability index[J]. Journal of Climate,2014-01-01,27(7)