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

anomaly over eastern North America and little temperature anomaly (<1 K) over the ocean, including the Gulf Stream Extension and Sargasso Sea ( Fig. 3a ). The mean event-day 1000-hPa geopotential anomaly shows a very specific strong circulation pattern ( Fig. 3b ). A steep west–east geopotential gradient lies centered at 66°W, which is consistent with strong northerly winds. This composite indicates that high heat flux days are associated with a characteristic circulation anomaly. This circulation is

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

Predictability (CLIVAR) Mode Water Dynamic Experiment (CLIMODE; http://www.climode.org/ ) field programs. In addition, a comprehensive set of diagnostics—mean, standard deviations, leading empirical orthogonal functions (EOFs), etc.—of various variables in these two WBCs is available online ( http://www.cdc.noaa.gov/WBC/ ). The leading modes of extratropical atmospheric variability, specifically the Pacific–North America (PNA) teleconnection (Wallace and Gutzler 1981) and the North Atlantic Oscillation (NAO

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

response patterns and their statistical significance are robust, particularly in the OE case, but the estimated amplitudes are quite sensitive to the lag and the assumed 2-month delay in the atmospheric response. A strong equivalent barotropic atmospheric signal lags the meridional shifts of the OE front. The response resembles an NPO/WP pattern in a positive phase for a northward shift and in a negative phase for a southward shift, with significant teleconnections over northeastern North America and

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

surface wave distortion of the marine wind profile in low-level ocean storms wind measurements . J. Phys. Oceanogr. , 25 , 2959 – 2971 . Latif , M. , and T. P. Barnett , 1994 : Causes of decadal climate variability over the North Pacific and North America . Science , 266 , 634 – 637 . Luksch , U. , and H. von Storch , 1992 : Modeling the low-frequency sea surface temperature variability in the North Pacific . J. Climate , 5 , 893 – 906 . Luo , Y. , Q. Liu , and L. M

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Lu Anne Thompson and Young-Oh Kwon

. Climate , 20 , 2416 – 2433 . Large , W. G. , and S. G. Yeager , 2004 : Diurnal to decadal global forcing for ocean and sea ice models: The data sets and flux climatologies. NCAR Tech. Rep. TN-460+STR, 105 pp . Large , W. G. , and G. Danabasoglu , 2006 : Attribution and impacts of upper-ocean biases in CCSM3. J. Climate , 19 , 2325 – 2346 . Latif , M. , and T. P. Barnett , 1996 : Decadal climate variability over the North Pacific and North America: Dynamics and predictability

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Daisuke Hotta and Hisashi Nakamura

the reversed triangular shape of the North American continent and by planetary waves forced by the Rockies. It should be noted that the pronounced meridional gradient in the climatological sensible heating across the GS off Cape Hatteras ( Fig. 2e ) is also contributed to by the oceanic cooling of the warm southerlies ahead of individual cyclones, which is particularly effective only to the north of the GS. This cooling tends to offset the contribution from the sensible heat release associated

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

geostrophic current velocities and SSTs. The seasonal mean current velocities are calculated as , where u and υ are climatological seasonal means of surface geostrophic current velocities in the eastward and northward directions, respectively. This paper adopts the terminology in Tomczak and Godfrey (2003) for the Gulf Stream system. The Gulf Stream that flows along the North American coast before reaching Cape Hatteras is called the Florida Current . At Cape Hatteras, the Gulf Stream separates

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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

. Seasonal temperature changes are likely important: the WBC warm core has a much weaker seasonal cycle than the colder waters or the air. The largest fluxes and associated cloud patterns may migrate offshore through the winter as shelf waters cool ( Young and Sikora 2003 ). Atmospheric circulation patterns such as the NAO and Pacific–North American pattern (PNA) modify the jet stream and the relative location of the jet stream and WBC. This may help determine whether the WBCs are important to synoptic

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

simulations. We focus on the period of 20–22 October, which for Tokage represents the end of the transition phase through the beginning of the extratropical phase. These simulations were carried out with an outer domain with a grid spacing of 45 km, which provided lateral boundary conditions for an inner domain with a grid spacing of 15 km using 1-way nesting. The inner nest extends from about 50° to 10°N and from about 105°E to a portion of the west coast of North America (i.e., nearly the entire North

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

amplitude in the upper troposphere, suggesting that the atmospheric circulation anomaly is remotely forced. In the following we use the stationary wave modeling approach to diagnose the MAM upper-tropospheric circulation response to the cold Pacific. Figure 5a shows that, in response to the prescribed cold Pacific pattern, there is a strong diabatic cooling response along the central and eastern tropical Pacific, straddled by diabatic heating anomalies to the north and south. Over North America, there

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