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

1995 ). Westward-propagating Rossby waves driven by basin-scale wind stress curl ( ∇ × τ ) anomalies ( Frankignoul et al. 1997 ) can initiate changes in ocean circulation in WBCs that lead to meridional displacement of the front ( Nakamura and Kazmin 2003 ) and geostrophic advection changes ( Dong and Kelly 2004 ). In addition, atmospheric teleconnections from the tropics can influence the surface heat flux and Ekman transports in WBCs ( Alexander et al. 2002 ). These processes are schematically

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Mototaka Nakamura and Shozo Yamane

various pressure levels were examined. The former two were chosen as the standard measures of the storm track variation, whereas the third was chosen as a measure of variation in the synoptic-scale wave forcing on the mean flow that originates from the anomalous B . The composites for cool months generally show structures that are defined more clearly than those for warm months. a. Anomalies in the atmosphere Composited anomalous B x and other atmospheric fields show interesting structures with

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Hailan Wang, Siegfried Schubert, Max Suarez, and Randal Koster

Climate Prediction Center (CPC) (more information about the data is available at ), and monthly zonal and meridional wind fields from the NCEP–NCAR reanalysis ( Kalnay et al. 1996 ) for the period 1948–2004. b. Methods To facilitate the investigation of the mechanisms by which the leading SST patterns affect U.S. precipitation, atmospheric moisture budget analysis and stationary wave modeling diagnosis are performed. The atmospheric

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Claude Frankignoul, Nathalie Sennéchael, Young-Oh Kwon, and Michael A. Alexander

1. Introduction Observational evidence that extratropical sea surface temperature (SST) anomalies have an influence on the large-scale atmospheric circulation during certain seasons has been found in the North Atlantic ( Czaja and Frankignoul 1999 , 2002 ; Rodwell and Folland 2002 ) and the North Pacific ( Liu et al. 2006 ; Frankignoul and Sennéchael 2007 , hereafter FS07 ). These air–sea interactions are highly relevant to the short-term climate predictability, as the SST anomalies tend to

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Haiming Xu, Hiroki Tokinaga, and Shang-Ping Xie

atmosphere acts to dampen the cool pool. This supports the notion that ocean hydrodynamics maintains the cool-water pool, which then forces atmospheric variations. The dynamical feedback from the atmospheric variations is not straightforward to evaluate and requires coupled modeling studies, such as the one by Seo et al. (2007) for tropical instability waves. Located upstream of the prevailing northwesterlies, Japan is not affected much by the Kuroshio meander. During periods of southerly winds, our

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James F. Booth, Lu Anne Thompson, Jérôme Patoux, Kathryn A. Kelly, and Suzanne Dickinson

Tropical Rainfall Measuring Mission (TRMM; Simpson et al. 1996 ), and free-tropospheric winds from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses Simmons and Gibson (2000) , Minobe et al. show that the SST has a significant influence on the tropospheric wind fields and precipitation patterns. The annually averaged rain pattern responds to changes in the location of the Gulf Stream in their 50-km-resolution atmospheric general circulation model (AGCM) runs. The SST also

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Shoshiro Minobe, Masato Miyashita, Akira Kuwano-Yoshida, Hiroki Tokinaga, and Shang-Ping Xie

the marine atmospheric boundary layer (MABL). In particular, unprecedented observations of surface winds by the Quick Scatterometer (QuikSCAT) satellite demonstrated that the wind divergence and wind curl exhibit coherent structures across ocean fronts or mesoscale ocean eddies (see reviews by Chelton et al. 2004 ; Xie 2004 ; Small et al. 2008 ). Such relations are globally observed for regions of strong SST gradients, that is, tropical instability waves ( Liu et al. 2000 ), the Kuroshio in the

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

sea surface temperature (SST) gradient across the APFZ, which has been confirmed by atmospheric general circulation model (AGCM) experiments by Inatsu and Hoskins (2004) . In addition, Nakamura and Sampe (2002 , hereafter NS02) pointed out that an excessively strong STJ in the midwinter North Pacific hinders baroclinic eddy growth despite the associated strong baroclinicity. They showed that transient eddies are likely to be trapped into the jet core, away from the surface baroclinic zone

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

1. Introduction The influence of the Gulf Stream on the atmosphere has been studied for the past century ( Page 1906 ; Strachan 1907 ). Carson (1950) proposed a hypothesis that the Gulf Stream causes stratus over the lower Atlantic coast through frontogenesis along the Gulf Stream with limited sounding data. Since the late 1960s, satellite observations, field campaigns, and numerical simulations enable detailed studies of atmospheric structures around the Gulf Stream. Raman and Riordan

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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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