Sensitivity of Midlatitude Storm Intensification to Perturbations in the Sea Surface Temperature near the Gulf Stream

Booth, James F.; Thompson, LuAnne; Patoux, Jérôme; Kelly, Kathryn A.

doi:10.1175/mwr-d-11-00195.1

Cited by 90 publications

(87 citation statements)

References 52 publications

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“…These results suggest that the SST front over the NWP enhances precipitation near the cyclone center through the large surface LHF from the Kuroshio and its extension. The precipitation enhancement causes the explosive deepening over the NWP in CNTL, consistent with regional model experiments for explosive cyclones due to SST fronts (Booth et al 2012;Iizuka et al 2013;Hirata et al 2015). The precipitation difference between CNTL and SMTHK associated with the explosive deepening also affects the upper troposphere.…”

Section: Composite Analysissupporting

confidence: 79%

“…The relationship between the storm track and sea surface temperature (SST) fronts associated with western boundary ocean currents, such as the Kuroshio, the Kuroshio Extension, the Oyashio, and the subpolar front in the northwestern Pacific (NWP) as well as the Gulf Stream in the northwestern Atlantic, has been investigated by analyzing observations, reanalysis data, and sensitivity experiments using global and regional atmospheric models in both ideal and realistic situations (Nakamura et al 2004;Minobe et al 2008;Taguchi et al 2009;Sampe et al 2010;Kuwano-Yoshida et al 2010b;Frankignoul et al 2011;Booth et al 2012;Ogawa et al 2012;Taguchi et al 2012;Iizuka et al 2013;KuwanoYoshida et al 2013;Small et al 2014;Smirnov et al 2015;O'Reilly and Czaja 2015;O'Reilly et al 2016;Ma et al 2015;Parfitt et al 2016). Nakamura et al (2004) summarized the relationship among storm tracks, jet streams, and midlatitude oceanic fronts based on observations and reanalyses.…”

Section: Introductionmentioning

confidence: 99%

“…This finding contradicts the results over the Gulf Stream in Small et al (2014), who showed that the Eady growth rate associated with the Gulf Stream significantly decreases in the smoothed SST front experiment compared with the observed SST front experiment using an AGCM. Furthermore, Booth et al (2012) showed that an extratropical cyclone is more sensitive to the absolute value of the SST than the SST gradient across the Gulf Stream.…”

Section: Introductionmentioning

confidence: 99%

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Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

2017

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The storm-track response to sea surface temperature (SST) fronts in the northwestern Pacific region is investigated using an atmospheric general circulation model with a 50-km horizontal resolution. The following two experiments are conducted: one with 0.258 daily SST data (CNTL) and the other with smoothed SSTs over an area covering SST fronts associated with the Kuroshio, the Kuroshio Extension, the Oyashio, and the subpolar front (SMTHK). The storm track estimated from the local deepening rate of surface pressure (LDR) exhibits a prominent peak in this region in CNTL in January, whereas the storm-track peak weakens and moves eastward in SMTHK. Storm-track differences between CNTL and SMTHK are only found in explosive deepening events with LDR larger than 1 hPa h 21. A diagnostic equation of LDR suggests that latent heat release associated with large-scale condensation contributes to the storm-track enhancement. The SST fronts also affect the large-scale atmospheric circulation over the northeastern Pacific Ocean. The jet stream in the upper troposphere tends to meander northward, which is associated with positive sea level pressure (SLP) anomalies in CNTL, whereas the jet stream flows zonally in SMTHK. A composite analysis for the northwestern Pacific SLP anomaly suggests that frequent explosive cyclone development in the northwestern Pacific in CNTL causes downstream positive SLP anomalies over the Gulf of Alaska. Cyclones in SMTHK developing over the northeastern Pacific enhance the moisture flux along the west coast of North America, increasing precipitation in that region.

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Section: Composite Analysissupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

2017

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“…However, one can also analyze the surface storm tracks based on meridional winds at 10 m. Booth et al (2010) show that the spatial patterns of storm tracks at 10 m differ from the free-tropospheric storm tracks due to the influence of ocean WBCs. Booth et al (2010) used physical arguments proposed by Sweet et al (1981) to suggest that the warm water in WBC creates regions with stronger atmospheric instability during cold air outbreaks associated with extratropical cyclones. The greater instability on the warm side of the WBC increases vertical mixing of momentum in these unstable regions creating stronger surface winds (a so-called momentum-mixing mechanism; see also Wallace et al 1989).…”

Section: Introductionmentioning

confidence: 99%

Spatial Patterns and Intensity of the Surface Storm Tracks in CMIP5 Models

Booth

Kwon

et al. 2017

J. Climate

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To improve the understanding of storm tracks and western boundary current (WBC) interactions, surface storm tracks in 12 CMIP5 models are examined against ERA-Interim. All models capture an equatorward displacement toward the WBCs in the locations of the surface storm tracks' maxima relative to those at 850 hPa. An estimated storm-track metric is developed to analyze the location of the surface storm track. It shows that the equatorward shift is influenced by both the lower-tropospheric instability and the baroclinicity. Basin-scale spatial correlations between models and ERA-Interim for the storm tracks, near-surface stability, SST gradient, and baroclinicity are calculated to test the ability of the GCMs' match reanalysis. An intermodel comparison of the spatial correlations suggests that differences (relative to ERA-Interim) in the position of the storm track aloft have the strongest influence on differences in the surface storm-track position. However, in the North Atlantic, biases in the surface storm track north of the Gulf Stream are related to biases in the SST. An analysis of the strength of the storm tracks shows that most models generate a weaker storm track at the surface than 850 hPa, consistent with observations, although some outliers are found. A linear relationship exists among the models between storm-track amplitudes at 500 and 850 hPa, but not between 850 hPa and the surface. In total, the work reveals a dual role in forcing the surface storm track from aloft and from the ocean surface in CMIP5 models, with the atmosphere having the larger relative influence.

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“…In the North Atlantic, the largest surface heat flux and its strongest interannual variability are found over the Gulf Stream (GS). The variations in the location and strength of the GS modify the cyclogenesis and the North Atlantic storm track (Cione et al 1993;Booth et al 2012;Small et al 2014), potentially influencing the broader-scale atmospheric and climate variability (Minobe et al 2008;O'Reilly et al 2016O'Reilly et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

et al. 2017

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The North Atlantic atmospheric circulation response to the meridional shifts of the Gulf Stream (GS) path is examined using a large ensemble of high-resolution hemispheric-scale Weather Research and Forecasting Model simulations. The model is forced with a broad range of wintertime sea surface temperature (SST) anomalies derived from a lag regression on a GS index. The primary result of the model experiments, supported in part by an independent analysis of a reanalysis dataset, is that the large-scale quasi-steady North Atlantic circulation response is remarkably nonlinear about the sign and amplitude of the SST anomaly chosen over a wide range of GS shift scenarios. The nonlinear response prevails over the weak linear response and resembles the negative North Atlantic Oscillation (NAO), the leading intrinsic mode of variability in the model and the observations. Further analysis of the associated dynamics reveals that the nonlinear responses are accompanied by the shift of the North Atlantic eddy-driven jet, which is reinforced, with nearly equal importance, by the high-frequency transient eddy feedback and the low-frequency wave-breaking events. Additional sensitivity simulations confirm that the nonlinearity of the circulation response is a robust feature found over the broad parameter space encompassing not only the varied SST but also the absence/presence of tropical influence, the varying lateral boundary conditions, and the initialization scheme. The result highlights the fundamental importance of the intrinsically nonlinear transient eddy dynamics and the eddy-mean flow interactions in generating the nonlinear downstream response to the meridional shifts in the Gulf Stream.

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Sensitivity of Midlatitude Storm Intensification to Perturbations in the Sea Surface Temperature near the Gulf Stream

Cited by 90 publications

References 52 publications

Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

Spatial Patterns and Intensity of the Surface Storm Tracks in CMIP5 Models

On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

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