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Daisuke Hotta and Hisashi Nakamura

mechanism of atmospheric baroclinicity (e.g., Stone 1978 ); however, it cannot explain the existence of such meridionally narrow baroclinic zones, as observed near the surface along the storm tracks. HV90 was the first to address this issue. Using a planetary wave model linearized about the observed wintertime zonal-mean flow with each of the transient eddy momentum and heat fluxes and diabatic heating imposed in the NH storm-track regions—namely, the North Atlantic and the North Pacific—as forcing

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Mototaka Nakamura and Shozo Yamane

tracks. This local version, or its simplified version, has been used successfully as an indicator of baroclinic wave generation in diagnostic studies of storm tracks in recent years as well ( Nakamura and Sampe 2002 ; Nakamura and Shimpo 2004 ; Nakamura et al. 2004 ). In our study, the North Atlantic part of which was reported in Nakamura and Yamane (2009 , hereafter Part I) , we define the near-surface baroclinic vector, B = B x i + B y j , where B x = −( g / θN )(∂ θ /∂ y ) and B y

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Takeaki Sampe, Hisashi Nakamura, Atsushi Goto, and Wataru Ohfuchi

the oceanic western boundary currents is important for strong diabatic heating in storm-track regions, which excites planetary waves that enhance baroclinicity around the storm-track regions. Nakamura et al. (2004 , 2008) argued that, because of the large heat capacity of the oceanic mixed layer and the strong thermal advection by confluent ocean currents, the presence of an oceanic front can exert a strong restoring effect on baroclinicity of the overlying atmosphere that is subject to

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Young-Oh Kwon, Michael A. Alexander, Nicholas A. Bond, Claude Frankignoul, Hisashi Nakamura, Bo Qiu, and Lu Anne Thompson

the deep ocean ML and the maintenance of the fronts by oceanic advection. The large heat and moisture fluxes to the south of the WBCs can enhance latent heating associated with cyclones, thereby acting to organize precipitation bands and the associated heat source regions for atmospheric planetary waves ( Hoskins and Valdes 1990 ; Minobe et al. 2008 ). Over most of the midlatitude oceans Q net variability is controlled largely by the atmosphere ( Cayan 1992 ; Frankignoul and Kestenare 2002

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Kathryn A. Kelly, R. Justin Small, R. M. Samelson, Bo Qiu, Terrence M. Joyce, Young-Oh Kwon, and Meghan F. Cronin

. (2008) found a measurable vertical velocity to heights of 300 hPa, together with an upper-tropospheric horizontal divergence signal directly over the GS, which they have argued is a direct response to SST-driven boundary layer interactions at the GS front ( Fig. 9 ). Minobe et al. (2008) suggest that deep convection is occurring over the GS and that planetary waves may consequently be excited by the deep heating, with far-field effects extending to Europe. An alternative interpretation is that

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Xujing Jia Davis, Lewis M. Rothstein, William K. Dewar, and Dimitris Menemenlis

RG exhibits different dynamics from the rest of the NPSTMW because of its vicinity to Kuroshio and KE. Previous studies have addressed the relationship between the basin-scale wind pattern and KOE variability. Specifically, the role of the first baroclinic Rossby wave has been shown to be important; the Rossby wave is the primary messenger of wind variability from the central Pacific to the KOE region over a time scale of 3–5 years ( Deser et al. 1999 ; Yasuda and Kitamura 2003 ), impacting

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Akira Kuwano-Yoshida, Shoshiro Minobe, and Shang-Ping Xie

significant wind difference tends to be confined near the Gulf Stream, while the 5-yr integrations are too short to filter out atmospheric internal variability on the planetary scale. Indeed, Reason (2001) conducts 11-member simulations to get a 95% significance level for the Agulhas Current influence on hemispherical-scale circulation, while Rodwell et al. (2004) suggest that 20 yr are necessary to identify significant responses to SST anomalies in the North Atlantic region. Minobe et al. (2008

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Masami Nonaka, Hisashi Nakamura, Bunmei Taguchi, Nobumasa Komori, Akira Kuwano-Yoshida, and Koutarou Takaya

: Sea surface temperature anomalies, planetary waves, and air-sea feedback in the middle latitudes. Rev. Geophys. , 23 , 357 – 390 . Hoskins , B. J. , and P. J. Valdes , 1990 : On the existence of storm-tracks. J. Atmos. Sci. , 47 , 1854 – 1864 . Hoskins , B. J. , M. E. McIntyre , and A. W. Robertson , 1985 : On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc. , 111 , 877 – 946 . Hunke , E. C. , and J. K. Dukowicz , 2002

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Bunmei Taguchi, Hisashi Nakamura, Masami Nonaka, and Shang-Ping Xie

migration of local SST fronts ( Xie et al. 2000 ; Seager et al. 2001 ; Nakamura and Kazmin 2003 ; Nonaka et al. 2006 , 2008 ) in association with incoming wind-forced oceanic Rossby waves ( Schneider and Miller 2001 ; Qiu 2003 ; Taguchi et al. 2007 ) and anomalous thermal advection by the Kuroshio and its extension (KE; Qiu 2000 ; Tomita et al. 2002 ; Vivier et al. 2002 ; Scott and Qiu 2003 ) and by the Oyashio and its subpolar extension (OE; Nonaka et al. 2008 ). Because they are caused by

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Nicholas A. Bond, Meghan F. Cronin, and Matthew Garvert

atmospheric circulation over the entire North Pacific basin through the downstream propagation of eddy activity/wave energy (e.g., Chang and Orlanski 1993 ). The present contribution on the subject of tropical to extratropical cyclone transition, and in particular the role of the ocean, is based on a series of high-resolution numerical weather prediction (NWP) model simulations of a single storm, Typhoon Tokage in October 2004. This case was selected because of the previous work carried out by Anwender

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