DOI: 10.1007/s00382-012-1429-6
Scopus记录号: 2-s2.0-84874950822
论文题名: Using seasonal hindcasts to understand the origin of the equatorial cold tongue bias in CGCMs and its impact on ENSO
作者: Vannière B. ; Guilyardi E. ; Madec G. ; Doblas-Reyes F.J. ; Woolnough S.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 40, 期: 2017-03-04 起始页码: 963
结束页码: 981
语种: 英语
英文关键词: CGCMs errors
; Cold tongue bias
; ENSO
; Seasonal forecasts
; Tropical Pacific
英文摘要: The cold equatorial SST bias in the tropical Pacific that is persistent in many coupled OAGCMs severely impacts the fidelity of the simulated climate and variability in this key region, such as the ENSO phenomenon. The classical bias analysis in these models usually concentrates on multi-decadal to centennial time series needed to obtain statistically robust features. Yet, this strategy cannot fully explain how the models errors were generated in the first place. Here, we use seasonal re-forecasts (hindcasts) to track back the origin of this cold bias. As such hindcasts are initialized close to observations, the transient drift leading to the cold bias can be analyzed to distinguish pre-existing errors from errors responding to initial ones. A time sequence of processes involved in the advent of the final mean state errors can then be proposed. We apply this strategy to the ENSEMBLES-FP6 project multi-model hindcasts of the last decades. Four of the five AOGCMs develop a persistent equatorial cold tongue bias within a few months. The associated systematic errors are first assessed separately for the warm and cold ENSO phases. We find that the models are able to reproduce either El Niño or La Niña close to observations, but not both. ENSO composites then show that the spurious equatorial cooling is maximum for El Niño years for the February and August start dates. For these events and at this time of the year, zonal wind errors in the equatorial Pacific are present from the beginning of the simulation and are hypothesized to be at the origin of the equatorial cold bias, generating too strong upwelling conditions. The systematic underestimation of the mixed layer depth in several models can also amplify the growth of the SST bias. The seminal role of these zonal wind errors is further demonstrated by carrying out ocean-only experiments forced by the AOCGCMs daily 10-meter wind. In a case study, we show that for several models, this forcing is sufficient to reproduce the main SST error patterns seen after 1 month in the AOCGCM hindcasts. © 2012 Springer-Verlag. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54930
Appears in Collections: 过去全球变化的重建
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作者单位: Lab. d'Océanographie et du Climat, Expérimentations et approches numériques, Institut Pierre Simon Laplace, Unité Mixte de Recherche 7159 CNRS/IRD/Université Pierre et Marie Curie/MNHN, Boîte 100-4, Place Jussieu, 75252 Paris Cedex 05, France; NCAS-Climate, Department of Meteorology, University of Reading, Reading, United Kingdom; Institut Català de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Institut Català de Ciènces del Clima (IC3), Barcelona, Spain
Recommended Citation:
Vannière B.,Guilyardi E.,Madec G.,et al. Using seasonal hindcasts to understand the origin of the equatorial cold tongue bias in CGCMs and its impact on ENSO[J]. Climate Dynamics,2013-01-01,40(2017-03-04)