DOI: 10.1007/s00382-012-1516-8
Scopus记录号: 2-s2.0-84876853402
论文题名: Initialisation and predictability of the AMOC over the last 50 years in a climate model
作者: Swingedouw D. ; Mignot J. ; Labetoulle S. ; Guilyardi E. ; Madec G.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 40, 期: 2017-09-10 起始页码: 2381
结束页码: 2399
语种: 英语
英文关键词: Atlantic meridional overturning circulation
; Decadal climate prediction
; Hindcast
; Mount Agung
; North Atlantic oscillation
; Ocean dynamics
; Predictability
; Volcanic eruptions
英文摘要: The mechanisms involved in Atlantic meridional overturning circulation (AMOC) decadal variability and predictability over the last 50 years are analysed in the IPSL-CM5A-LR model using historical and initialised simulations. The initialisation procedure only uses nudging towards sea surface temperature anomalies with a physically based restoring coefficient. When compared to two independent AMOC reconstructions, both the historical and nudged ensemble simulations exhibit skill at reproducing AMOC variations from 1977 onwards, and in particular two maxima occurring respectively around 1978 and 1997. We argue that one source of skill is related to the large Mount Agung volcanic eruption starting in 1963, which reset an internal 20-year variability cycle in the North Atlantic in the model. This cycle involves the East Greenland Current intensity, and advection of active tracers along the subpolar gyre, which leads to an AMOC maximum around 15 years after the Mount Agung eruption. The 1997 maximum occurs approximately 20 years after the former one. The nudged simulations better reproduce this second maximum than the historical simulations. This is due to the initialisation of a cooling of the convection sites in the 1980s under the effect of a persistent North Atlantic oscillation (NAO) positive phase, a feature not captured in the historical simulations. Hence we argue that the 20-year cycle excited by the 1963 Mount Agung eruption together with the NAO forcing both contributed to the 1990s AMOC maximum. These results support the existence of a 20-year cycle in the North Atlantic in the observations. Hindcasts following the CMIP5 protocol are launched from a nudged simulation every 5 years for the 1960-2005 period. They exhibit significant correlation skill score as compared to an independent reconstruction of the AMOC from 4-year lead-time average. This encouraging result is accompanied by increased correlation skills in reproducing the observed 2-m air temperature in the bordering regions of the North Atlantic as compared to non-initialized simulations. To a lesser extent, predicted precipitation tends to correlate with the nudged simulation in the tropical Atlantic. We argue that this skill is due to the initialisation and predictability of the AMOC in the present prediction system. The mechanisms evidenced here support the idea of volcanic eruptions as a pacemaker for internal variability of the AMOC. Together with the existence of a 20-year cycle in the North Atlantic they propose a novel and complementary explanation for the AMOC variations over the last 50 years. © 2012 Springer-Verlag. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54982
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: LSCE/IPSL, Gif-sur-Yvette, France; LOCEAN/IPSL, Paris, France; NCAS-Climate, University of Reading, Reading, United Kingdom; NOCS, Southampton, United Kingdom
Recommended Citation:
Swingedouw D.,Mignot J.,Labetoulle S.,et al. Initialisation and predictability of the AMOC over the last 50 years in a climate model[J]. Climate Dynamics,2013-01-01,40(2017-09-10)