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

standard deviation estimated for the individual seasons. The subseasonal variability in SHF is enhanced within a zonal belt in the vicinity of the oceanic frontal zone east of Japan for both seasons (not shown). The effects of the oceanic frontal zone are depicted in detail in Fig. 5 , which shows latitudinal profiles at 150°E of SHF statistics, including its seasonal mean, standard deviation, and skewness, in addition to the meridional gradients of SST and SAT. In each of the seasons, the observed

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

mechanism that connects the Gulf Stream to the upper troposphere ( Hoskins and Valdes 1990 ; Nakamura et al. 2004 ). The climatic effects of the Gulf Stream are still under debate in the literature. Frankignoul et al. (2001) find no evidence that interannual variability in the Gulf Stream’s path has a direct impact on large-scale atmospheric circulation from an atmospheric reanalysis. Based on atmospheric general circulation model (GCM) experiments, Seager et al. (2002) suggest that the Gulf Stream

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

atmosphere (e.g., Czaja and Frankignoul 2002 ; Ciasto and Thompson 2004 ; Watanabe et al. 2006 ). Observational studies, however, suffered from the short length of available data, insufficient to determine the contribution of ocean-to-atmosphere influences, which can be masked by energetic atmosphere-to-ocean influences. Numerical studies of atmospheric responses to midlatitude SST anomalies, on the other hand, showed diverse results, probably because the effects of eddy–mean flow interactions induced

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Haiming Xu, Hiroki Tokinaga, and Shang-Ping Xie

response. Such atmospheric effects, however, have never been documented in the literature, largely because of the lack of comprehensive observations. In the summer (June–August) of 2004, a large meander with 800–1000-km length took place for the first time since 1991 and persisted until the next summer. A small meander southeast of Kyushu that occurred in December 2003 triggered the subsequent development of a large meander ( Usui et al. 2008 ). This large meander event is the first and only event

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

1. Introduction The largest wintertime heat fluxes from the ocean to the atmosphere in the North Atlantic occur in the region of the Gulf Stream extension and the adjacent waters of the northwestern portion of the subtropical gyre ( Esbensen and Kushnir 1981 ; Josey et al. 1999 ). These heat fluxes are supported in the ocean by advective heat convergence in the Gulf Stream and by seasonal heat storage in the surrounding waters, especially the subtropical mode water to the south and east of the

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

smoothing, seasonal effects are negligible. The strong influence of the ENSO removal is due to the second ENSO PC, which is highly anticorrelated ( r = −0.54) with the KEI, consistent with Fig. 6 (top). Figure 6 (bottom) shows that the tropical SST associated with the KEI was successfully removed by the multivariate regression, except for a small signal in the western Indian Ocean and in the eastern Pacific. To search for an atmospheric impact of the meridional shifts of the KE jet, we applied the

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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

the midlatitude westerlies, passing over the cold coastal ocean and then over the warm WBCs. The associated air–sea interaction processes include phenomena that cover a wide range of scales, from frontal effects associated with the mesoscale sea surface temperature gradients across the WBCs, to the ocean basin and even global scales associated with the midlatitude storm tracks. Note that the term “storm track” frequently refers to (Eulerian) regions of high wind variability at synoptic time scales

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

sensible and latent heat, which themselves represent the primary energy source for tropical cyclones (e.g., Emanuel 1986 ). One might expect that anomalously warm SSTs would tend to be associated with delayed transitions for storms moving poleward, and that cold SSTs would be associated with hastened transitions, all other factors being equal. Thus, the effects of the regional SST on these storms may not have just local manifestations. Modifications in storm properties have potential impacts on the

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

. , 29 , 1276 . doi:10.1029/2001GL014043 . Peng , S. , W. A. Robinson , S. Li , and M. P. Hoerling , 2005 : Tropical Atlantic SST forcing of coupled North Atlantic seasonal responses. J. Climate , 18 , 480 – 496 . Peng , S. , W. A. Robinson , S. Li , and M. A. Alexander , 2006 : Effects of Ekman transport on the NAO response to a tropical Atlantic SST anomaly. J. Climate , 19 , 4803 – 4818 . Pierce , D. W. , T. P. Barnett , N. Schneider , R. Saravanan , D

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

by the National Oceanic and Atmospheric Administration to monitor the EASM strength variations (see online at http://www.cpc.noaa.gov/products/Global_Monsoons/Asian_Monsoons/monsoon_index.shtml ). The I LZ is based on seasonal alternation in wind direction over monsoon domains. It is defined as where V W and V i are the climatological winter wind vector as the reference state (here averaged from 1968 to 1996) and monthly wind vectors at a point, respectively, and V = ( V W + V S )/2 is

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