North Atlantic decadal regimes in a coupled GCM simulation

Raible, Christoph C.; Luksch, Ute; Fraedrich, Klaus; Voss, Reinhard

doi:10.1007/s003820100176

Cited by 66 publications

(71 citation statements)

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“…Analysis and validation of the ECHO-G performance in reproducing internal climate variability in CTRL in comparison with instrumental variability can be found in Min et al (2005a,b); further details can be found in Raible et al (2001Raible et al ( , 2004Raible et al ( , 2005 who analyze North Atlantic atmospheric circulation in other control simulations with the same model. Analyses of different aspects of the forced simulations used herein can be found in the literature Zorita et al, 2003Zorita et al, , 2005González-Rouco et al, 2003aBeltrami et al, 2006b;Gouirand et al, 2007a,b;Stevens et al, 2007).…”

Section: Gcm Simulationsmentioning

confidence: 99%

Borehole climatology: a discussion based on contributions from climate modeling

et al. 2009

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Abstract. Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries.The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change.The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of Correspondence to: J. F. González-Rouco (fidelgr@fis.ucm.es) realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments.

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Section: Gcm Simulationsmentioning

confidence: 99%

Borehole climatology: a discussion based on contributions from climate modeling

et al. 2009

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“…4) on the basis of the criterion that they lasted over at least 30 years. They are called ''active'' (corresponding to the terms used by Raible et al 2001) if the coupling is strong and ''inactive'' if it is weak. Note that the chosen periods are not equal in length.…”

Section: Pna Nao and North Atlantic And North Pacific Storm Tracksmentioning

confidence: 99%

“…A variable link is, however, tentatively supported by the study of Knippertz et al (2003), who looked at the changing correlations between ENSO and the NAO. Further, Raible et al (2001) observed two decadal regimes for the NAO-variability in ECHAM4 model simulations: (a) phases with enhanced low-frequency variability (''active'') characterized by regional modes over the NA and NP (here with a barocline PNA mode) and (b) phases with reduced low-frequency variability (''inactive''), characterized by a global mode with a dominant PNA pattern and stronger links to SST anomalies over the tropical Pacific.…”

Section: Introductionmentioning

confidence: 95%

The variable link between PNA and NAO in observations and in multi-century CGCM simulations

2010

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The link between the Pacific/North American pattern (PNA) and the North Atlantic Oscillation (NAO) is investigated in reanalysis data (NCEP, ERA40) and multicentury CGCM runs for present day climate using three versions of the ECHAM model. PNA and NAO patterns and indices are determined via rotated principal component analysis on monthly mean 500 hPa geopotential height fields using the varimax criteria. On average, the multicentury CGCM simulations show a significant anti-correlation between PNA and NAO. Further, multi-decadal periods with significantly enhanced (high anti-correlation, active phase) or weakened (low correlations, inactive phase) coupling are found in all CGCMs. In the simulated active phases, the storm track activity near Newfoundland has a stronger link with the PNA variability than during the inactive phases. On average, the reanalysis datasets show no significant anti-correlation between PNA and NAO indices, but during the sub-period 1973-1994 a significant anti-correlation is detected, suggesting that the present climate could correspond to an inactive period as detected in the CGCMs. An analysis of possible physical mechanisms suggests that the link between the patterns is established by the baroclinic waves forming the North Atlantic storm track. The geopotential height anomalies associated with negative PNA phases induce an increased advection of warm and moist air from the Gulf of Mexico and cold air from Canada. Both types of advection contribute to increase baroclinicity over eastern North America and also to increase the low level latent heat content of the warm air masses. Thus, growth conditions for eddies at the entrance of the North Atlantic storm track are enhanced. Considering the average temporal development during winter for the CGCM, results show an enhanced Newfoundland storm track maximum in the early winter for negative PNA, followed by a downstream enhancement of the Atlantic storm track in the subsequent months. In active (passive) phases, this seasonal development is enhanced (suppressed). As the storm track over the central and eastern Atlantic is closely related to the NAO variability, this development can be explained by the shift of the NAO index to more positive values.

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“…[3] One explanation could be that the NAO itself is not stationary in time with a change in the position of its centers of action [Christoph et al, 2000;Raible et al, 2005] and/or with a change in the regime behaviour [Raible et al, 2001;Casty et al, 2005] leading to a different signal in proxy records. Additionally, there is essentially no correlation of ice-core accumulation with the NAOI in other parts of the GrIS or average GrIS accumulation rates [Hanna et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

Reconstructing climate variability from Greenland ice sheet accumulation: An ERA40 study

Hutterli

Raible

Stocker

2005

Geophysical Research Letters

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Re‐analysis data covering the period 1958–2001 are used to investigate the relationship between regional, inter‐annual snow accumulation variability over the Greenland Ice Sheet (GrIS) and large scale circulation patterns, cyclone frequency, and strength. Four regions of the GrIS have been identified that are highly independent with respect to accumulation variability. Accumulation indices of three of these regions are associated with distinct large‐scale circulation patterns: Central‐western GrIS reveals an inverse relationship with a NAO‐like pattern, the south‐west a positive correlation with a high pressure bridge from central North Atlantic to Scandinavia, and the south‐eastern GrIS a positive correlation with a high‐pressure anomaly over the Greenland Sea. These large‐scale patterns also impact European climate in different ways. Accumulation variability in north‐eastern GrIS, however, is dominated by cyclones originating from the Greenland Sea. Thus, Greenland ice core accumulation records offer the potential to reconstruct various large‐scale circulation patterns and regional storm activity.

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North Atlantic decadal regimes in a coupled GCM simulation

Cited by 66 publications

References 0 publications

Borehole climatology: a discussion based on contributions from climate modeling

Borehole climatology: a discussion based on contributions from climate modeling

The variable link between PNA and NAO in observations and in multi-century CGCM simulations

Reconstructing climate variability from Greenland ice sheet accumulation: An ERA40 study

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