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Mototaka Nakamura and Shozo Yamane

location dependent because of topography. Both ∇ θ 2m and N were calculated locally as in Hoskins and Valdes (1990) and Nakamura and Shimpo (2004) . The entire 45 yr from September 1957 to August 2002 were used for the Northern Hemisphere. To resolve the dominant modes in B arising from the land–sea temperature contrast, one may need much higher horizontal resolution in the data. The relatively coarse horizontal resolution of the data may artificially suppress the significance of the

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

1. Introduction Satellite data and high-resolution general circulation models results show that sharp sea surface temperature (SST) fronts influence the local time-mean and transient dynamics of the atmosphere. Minobe et al. (2008) show that the differential heating across the Gulf Stream has a significant impact on the divergence of the time-mean winds throughout the troposphere. Using surface wind measurements from the Quick Scatterometer (QuikSCAT; Liu 2002 ), SST measurements from

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

persistent droughts and pluvials over western North America: 1856–2000. J. Climate , 18 , 4065 – 4088 . Seager , R. , N. Graham , C. Herweijer , A. L. Gordon , Y. Kushnir , and E. Cook , 2007 : Blueprints for Medieval hydroclimate. Quat. Sci. Rev. , 26 , (19–21) . 2322 – 2336 . doi:10.1016/j.quascirev.2007.04.020 . Stöckli , R. , and Coauthors , 2008 : Use of FLUXNET in the Community Land Model development. J. Geophys. Res. , 113 , G01025 . doi:10.1029/2007JG000562

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Jeffrey Shaman, R. M. Samelson, and Eric Skyllingstad

Atlantic Gulf Stream extension and STMW outcrop region. We examine the tropospheric structure associated with high daily wintertime heat fluxes in this region. Trends in the 1948–2007 National Centers for Environmental Prediction (NCEP)–National Center for Atmospheric Research (NCAR) reanalysis record are then described. Changes in storm activity and low-level baroclinicity in the region are examined as well. Section 2 describes the data used for this analysis. Section 3 categorizes the daily

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Jianping Li, Zhiwei Wu, Zhihong Jiang, and Jinhai He

a phenomenon are still controversial, larger thermal gradient and increased moisture transport are believed to be two principal factors responsible for the enhanced ISM. Kumar et al. (1999) and Hu et al. (2000) revealed that increased surface air temperatures Ts over Eurasia in winter and spring may favor the enhanced land–ocean thermal gradient conducive to a strong ISM. Meehl and Arblaster (2003) and Ueda et al. (2006) suggested that a larger moisture flux convergence resulting from a

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Terrence M. Joyce, Young-Oh Kwon, and Lisan Yu

–decadal atmospheric variability for the North Pacific, and Alexander et al. (2006) have looked at large-scale SST and wintertime storm tracks using both model and reanalysis data. These approaches recognize that interannual–decadal time-scale changes in the ocean require one to examine similar time scales for changes in the overlying atmosphere as well. We will follow this line of thinking here, differing in that our focus is interannual–decadal measures of atmospheric synoptic variability and not variations in

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Haiming Xu, Hiroki Tokinaga, and Shang-Ping Xie

observations. We show that the LM produces large anomalies in SST, surface wind, cloud, and precipitation. We use a regional atmospheric model, which successfully simulates the observed atmospheric response, to investigate the LM effect on the atmosphere. In the rest of the note, section 2 describes the satellite data, section 3 presents results of the satellite data analysis, section 4 describes an atmospheric model and presents its simulations, and section 5 is a summary. 2. Data This study uses

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Lu Anne Thompson and Young-Oh Kwon

difference between two 8-yr periods before and after the 1976 climate shift is larger than in observations. There are questions about whether the ocean is adequately sampled to give a realistic representation of the true variability in observational analyses; however, we argue below, using new high-resolution datasets and an analysis of a CCSM3 simulation, that low-resolution models consistently overrepresent the SST variability in this region. While the large-scale adjustment of the gyre circulation to

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

and Godfrey 2003 ). Its influences on weather variability have been studied extensively. Sanders (1986) showed that the most rapid deepening bomb cyclones tend to move along the axis of the Gulf Stream. Strong ocean-to-atmosphere turbulent heat flux is observed over the Gulf Stream (e.g., Doyle and Warner 1993 ; Zolina and Gulev 2003 ). Kuo et al. (1991) and Reed et al. (1993) demonstrated that latent heat release is important in cyclogenesis using regional atmospheric models. Mesoscale

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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

atmospheric eddy heat fluxes will act to reduce the sharp meridional air temperature gradients (e.g., Holton 2004 ), the WBC SST front, which is maintained by advection and subsurface heat storage, can restore the air temperature gradient. Hoskins and Valdes (1990) used reanalysis data to show that the diabatic heating in the lower and midtroposphere, which occurs as synoptic storms pass across the land–sea boundary and then over the WBCs, acts to sustain the baroclinicity. They hypothesized that as

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