The response of the Pacific storm track and atmospheric circulation to Kuroshio Extension variability

O’Reilly, Christopher H.; Czaja, Arnaud

doi:10.1002/qj.2334

Cited by 140 publications

(113 citation statements)

References 65 publications

(68 reference statements)

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“…In addition, it was based on temperature profiles that may be too shallow to accurately define the KE path. O'Reilly and Czaja (2015) found that, during the 1992-2010 period, the transient eddy heat transport in winter and spring has a dipolar structure with an increase in the western North Pacific and a decrease in the east when the KE is shifted north and the SST front is stronger, unlike in the present analysis. They used (unlagged) composites based on an index derived from a maximum covariance analysis between SST and SSH gradients during 2002-10.…”

Section: Discussioncontrasting

confidence: 78%

“…In this period, their index is very similar to Qiu et al's (2014) index, and we verified that the two indices lead to similar regression patterns in SLP, geopotential, Eady growth rate, and eddy heat transport, albeit different from those discussed here, presumably because the sample is too short to emphasize the decadal KE changes that dominate the response in the present paper. However, the KE indices differ considerably during 1992-2001 when O'Reilly and Czaja's (2015) index was extended by SSH projection, with much larger decadal changes in Qiu et al's (2014) index. Whether the differences in the two analyses are primarily due to the differences in the KE indices or their dominant time scale, or nonstationarity in the atmosphere, remains to be established.…”

Section: Discussionmentioning

confidence: 95%

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Influence of the Decadal Variability of the Kuroshio Extension on the Atmospheric Circulation in the Cold Season

et al. 2016

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The atmospheric response to the Kuroshio Extension (KE) variability during 1979-2012 is investigated using a KE index derived from sea surface height measurements and an eddy-resolving ocean general circulation model hindcast. When the index is positive, the KE is in the stable state, strengthened and shifted northward, with lower eddy kinetic energy, and the Kuroshio-Oyashio Extension (KOE) region is anomalously warm. The reverse holds when the index is negative. Regression analysis shows that there is a coherent atmospheric response to the decadal KE fluctuations between October and January. The KOE warming generates an upward surface heat flux that leads to local ascending motions and a northeastward shift of the zones of maximum baroclinicity, eddy heat and moisture fluxes, and the storm track. The atmospheric response consists of an equivalent barotropic large-scale signal, with a downstream high and a low over the Arctic. The heating and transient eddy anomalies excite stationary Rossby waves that propagate the signal poleward and eastward. There is a warming typically exceeding 0.6 K at 900 hPa over eastern Asia and western United States, which reduces the snow cover by 4%-6%. One month later, in November-February, a high appears over northwestern Europe, and the hemispheric teleconnection bears some similarity with the Arctic Oscillation. Composite analysis shows that the atmospheric response primarily occurs during the stable state of the KE, while no evidence of a significant large-scale atmospheric response is found in the unstable state. Arguments are given to explain this strong asymmetry.

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Section: Discussioncontrasting

confidence: 78%

Section: Discussionmentioning

confidence: 95%

Influence of the Decadal Variability of the Kuroshio Extension on the Atmospheric Circulation in the Cold Season

et al. 2016

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“…The remote atmospheric response to oceanic fronts and eddies, in comparison to the local response, is generally more difficult to identify using direct observations (Frankignoul et al 2011;O'Reilly and Czaja 2015); hence, most existing studies are based on high-resolution model experiments. A particularly useful experimental strategy for this type of study is a set of twin atmospheric model simulations, one of which is forced by observed SSTs and the other by spatially smoothed SSTs (Xie et al 2002;Minobe et al 2008;Kuwano-Yoshida et al 2010;Small et al 2014b;Piazza et al 2016;X.…”

Section: The Global Hydrological Cyclementioning

confidence: 99%

“…Ma et al 2015X. Ma et al , 2017O'Reilly et al 2017), storm-track strength (Small et al 2014b), and remote rainfall response along the U.S. West Coast to Kuroshio eddies (X. Ma et al , 2017; Kuwano-Yoshida and Minobe 2017).…”

Section: The Global Hydrological Cyclementioning

confidence: 99%

The Benefits of Global High Resolution for Climate Simulation: Process Understanding and the Enabling of Stakeholder Decisions at the Regional Scale

Roberts

Vidale

Senior

et al. 2018

Bulletin of the American Meteorological Society

128

107

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The time scales of the Paris Climate Agreement indicate urgent action is required on climate policies over the next few decades, in order to avoid the worst risks posed by climate change. On these relatively short time scales the combined effect of climate variability and change are both key drivers of extreme events, with decadal time scales also important for infrastructure planning. Hence, in order to assess climate risk on such time scales, we require climate models to be able to represent key aspects of both internally driven climate variability and the response to changing forcings. In this paper we argue that we now have the modeling capability to address these requirements—specifically with global models having horizontal resolutions considerably enhanced from those typically used in previous Intergovernmental Panel on Climate Change (IPCC) and Coupled Model Intercomparison Project (CMIP) exercises. The improved representation of weather and climate processes in such models underpins our enhanced confidence in predictions and projections, as well as providing improved forcing to regional models, which are better able to represent local-scale extremes (such as convective precipitation). We choose the global water cycle as an illustrative example because it is governed by a chain of processes for which there is growing evidence of the benefits of higher resolution. At the same time it comprises key processes involved in many of the expected future climate extremes (e.g., flooding, drought, tropical and midlatitude storms).

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“…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%

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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The response of the Pacific storm track and atmospheric circulation to Kuroshio Extension variability

Cited by 140 publications

References 65 publications

Influence of the Decadal Variability of the Kuroshio Extension on the Atmospheric Circulation in the Cold Season

Influence of the Decadal Variability of the Kuroshio Extension on the Atmospheric Circulation in the Cold Season

The Benefits of Global High Resolution for Climate Simulation: Process Understanding and the Enabling of Stakeholder Decisions at the Regional Scale

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

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