The Differences between Early and Midwinter Atmospheric Responses to Sea Surface Temperature Anomalies in the Northwest Atlantic

Peng, Shiling; Mysak, Lawrence A.; Derome, Jacques; Ritchie, Harold; Dugas, B.

doi:10.1175/1520-0442(1995)008<0137:tdbeam>2.0.co;2

Cited by 145 publications

(113 citation statements)

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“…The sign, magnitude, and spatial pattern of this feedback inferred from GCM results is, however, controversial; compare, for example, Peng et al (1995Peng et al ( , 1997 and Kushnir and Held (1996). In general, the linear response of the atmospheric circulation to SST anomalies associated with mid-latitude variability is weak; see, however, Feliks et al (2004Feliks et al ( , 2007.…”

Section: Introductionmentioning

confidence: 99%

A mechanistic model of mid-latitude decadal climate variability

Kravtsov

Dewar

Ghil

et al. 2008

Physica D: Nonlinear Phenomena

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A simple heuristic model of coupled decadal ocean-atmosphere modes in middle latitudes is developed. Previous studies have treated atmospheric intrinsic variability as a linear stochastic process modified by a deterministic coupling to the ocean.The present paper takes an alternative view: based on observational, as well as process modeling results, it represents this variability in terms of irregular transitions between two anomalously persistent, high-latitude and low-latitude jet-stream states. Atmospheric behavior is thus governed by an equation analogous to that describing the trajectory of a particle in a double-well potential, subject to stochastic forcing. Oceanic adjustment to a positional shift in the atmospheric jet involves persistent circulation anomalies maintained by the action of baroclinic eddies; this process is parameterized in the model as a delayed oceanic response. The associated sea-surface temperature anomalies provide heat fluxes that affect atmospheric circulation by modifying the shape of the double-well potential. If the latter coupling is strong enough, the model's spectrum exhibits a peak at a periodicity related to the ocean's eddy-driven adjustment time. A nearly analytical approximation of the coupled model is used to study the sensitivity of this behavior to key model parameters.

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Section: Introductionmentioning

confidence: 99%

A mechanistic model of mid-latitude decadal climate variability

Kravtsov

Dewar

Ghil

et al. 2008

Physica D: Nonlinear Phenomena

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“…Such an SSTA is located in one of the most dynamically, and thermodynamically active regions of the extratropical atmosphere (Namias 1973), so its possible influence on the overlying atmosphere has been the focus of numerous investigations (e.g., Namias 1964 and1973;PS85;Peng et al 1995;Kushnir and Held 1996). However, diverse and inconsistent results are obtained by different authors, and, correspondingly, whether the SSTA affects remotely on the Urals or not, is also inconsistent.…”

Section: Introductionmentioning

confidence: 99%

Impact of Northwest Atlantic SST Anomalies on the Circulation over the Ural Mountains during Early Winter

Li¹

2004

Journal of the Meteorological Society of Japan

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Both the observed background circulation and the northwest Atlantic sea surface temperature anomalies (SSTA) associated with the circulation anomaly over the Ural Mountains during early winter (October-December) are investigated, and it is shown that a positive height anomaly over the Urals is remotely linked to a positive SSTA by an upper wave-train-like anomaly chain across the North Atlantic and coastal Europe. To investigate whether and how the SSTA affects the circulation over the Urals, large-ensemble atmospheric general circulation model (GCM) experiments are conducted, and the results show that the SSTA forces a similar wave-train-like anomaly chain, resulting in a positive geopotential height anomaly over the Urals.The mechanism that maintains the response is diagnosed by investigating the roles of anomalous diabatic heating, and transient vorticity forcing, via a linear baroclinic model (LBM). The results suggest that the two upstream anomalies in the chain are largely maintained by anomalous transient vorticity forcing, although it is modulated by anomalous diabatic heating. In contrast, the Ural response is largely maintained by anomalous diabatic heating. To mimic the initial mechanism of the response, an idealized heating representing the initial SSTA-induced heating is prescribed. The LBM response to the idealized heating is obtained, and then transient feedback to the heating-induced anomalous flow is simulated, via a linear storm track model (STM). The LBM responses to the anomalous transient vorticity forcing resulting from the idealized heating resembles the GCM simulation upstream, but is not significant over the Urals. This suggests further that the Ural response is triggered, and maintained, by anomalous diabatic heating.

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“…The second is an anticyclonic vorticity anomaly with an equivalent barotropic structure over warm SST anomaly (e.g. Palmer and Sun, 1985;Lau and Nath, 1994;Peng et al, 1995;Peng and Whitaker, 1999).…”

Section: Introductionmentioning

confidence: 99%

Statistics of locally coupled ocean and atmosphere intraseasonal anomalies in Reanalysis and AMIP data

Peña

Kalnay

Cai

2003

Nonlin. Processes Geophys.

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Abstract. We apply a simple dynamical rule to determine the dominant forcing direction in locally coupled oceanatmosphere anomalies in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/ NCAR) reanalysis data. The rule takes into account the phase relationship between the low-level vorticity anomalies and the Sea Surface Temperature (SST) anomalies. Analysis of the frequency of persistent coupled anomalies for five-day average data shows that, in general, the ocean tends to force the atmosphere in the tropics while the atmosphere tends to force the ocean in the extratropics. The results agree well with those obtained independently using lagged correlations between atmospheric and oceanic variables, suggesting that the dynamical rule is generally valid.A similar procedure carried out using data from the NCEP global model run with prescribed SST (in which the coupling is one-way, with the ocean always forcing the atmosphere) produces fewer coupled anomalies in the extratropics. They indicate, not surprisingly, an increase in oceandriving anomalies in the model. In addition, and very importantly, there is a strong reduction of persistent atmospheredriving anomalies, indicating that the one-way interaction of the ocean in the model run may provide a spurious negative feedback that damps atmospheric anomalies faster than observed.

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The Differences between Early and Midwinter Atmospheric Responses to Sea Surface Temperature Anomalies in the Northwest Atlantic

Cited by 145 publications

References 0 publications

A mechanistic model of mid-latitude decadal climate variability

A mechanistic model of mid-latitude decadal climate variability

Impact of Northwest Atlantic SST Anomalies on the Circulation over the Ural Mountains during Early Winter

Statistics of locally coupled ocean and atmosphere intraseasonal anomalies in Reanalysis and AMIP data

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