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Steven E. Koch, Wayne Feltz, Frédéric Fabry, Mariusz Pagowski, Bart Geerts, Kristopher M. Bedka, David O. Miller, and James W. Wilson

observed precipitation patterns, given the sensitivity of the density current and bore occurrence to this factor. Other necessary ingredients for successful numerical simulation include the proper simulation of the waveguide, such as a frontal system acting as a horizontal delimiter, and the strength of the low-level jet, which acts as an important mechanism for trapping vertical wave energy propagation. Acknowledgments We express our appreciation to the University Corporation for Atmospheric Research

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Michael J. Ventrice, Christopher D. Thorncroft, and Matthew A. Janiga

convectively coupled equatorial atmospheric Kelvin wave (CCKW) over the eastern tropical Atlantic. AEWs, the dominant synoptic weather systems observed over Africa and the tropical Atlantic during Northern Hemisphere boreal summer, are westward-propagating tropical waves that grow along the African easterly jet (AEJ) (e.g., Reed et al. 1977 ; Thompson et al. 1979 ; Avila and Pasch 1992 ; Mekonnen et al. 2006 ). Before reaching the coast of West Africa, the AEWs that later develop into tropical cyclones

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Michael J. Ventrice and Chris D. Thorncroft

et al. 2006 ; Thorncroft et al. 2008 ). These studies have proposed that AEWs are triggered by convection in the entrance region of the AEJ. Thorncroft et al. (2008) suggest that AEWs rely on the presence of intense upstream convective triggers linked to African topography. We argue here that convectively coupled equatorial atmospheric Kelvin waves (CCKWs) can provide such triggers over African topography by providing a favorable environment for convection and wave growth. This concept

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F. Martin Ralph, Paul J. Neiman, George N. Kiladis, Klaus Weickmann, and David W. Reynolds

extreme precipitation in North America. In Fig. 2 , SSM/I imagery displays a connection in IWV between the flood event across the Pacific Northwest and deep moisture regions within the near-equatorial intertropical convergence zone (ITCZ) over the central Pacific. Such connections have been well documented for atmospheric rivers affecting the west coast of North America (e.g., Ralph et al. 2004 ; Neiman et al. 2008a , b ). Wave energy propagating into the equatorial east Pacific from the

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Lisa S. Darby and Gregory S. Poulos

Springs region, the Federal Aviation Administration (FAA), in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and the National Center for Atmospheric Research (NCAR), sponsored the Mountain-induced Clear Air Turbulence (MCAT) field experiment in the winter and spring of 1997 ( Bedard and Neilley 1998 ). A number of lee-wave events were sampled by a NOAA Doppler lidar during MCAT. This paper describes a single case on 1 April 1997, with an emphasis on the 0000–1200 UTC

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Vivien Matthias and Marlene Kretschmer

generally supportive of this statement. While strongest and most persistent fluxes were found before and during event 2 (i.e., before the SSW), the first event was linked to a short period of enhances wave activity ( Fig. 3b ). Nevertheless, results for event 2 show that reflection can occur during the wave pulse leading to a SSW, indicating once more the individual characteristics of each major SSW ( Tripathi et al. 2015 ). Overall, it remains thus an important task to better understand the atmospheric

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Piet Termonia

1. Introduction Initial states of atmospheric models are usually unbalanced. When used as initial states of model runs, they will adjust to equilibrium by producing unrealistically high gravity–inertia waves. Initialization is the technique that creates balanced states by removing these waves. The technique of digital-filtering initialization (DFI) introduced by Lynch (1990) is based on the fact that the gravity–inertia waves lie in a different part of the frequency spectrum than the

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J. V. Ratnam, S. K. Behera, Y. Masumoto, and T. Yamagata

precipitation variations at the western Pacific are known to generate teleconnections (Pacific–Japan teleconnection; Nitta 1987 ) modulating the precipitation over Japan. The Pacific–Japan teleconnection is an atmospheric Rossby wave response to the heating over the western Pacific extending from the Philippine Sea to the extratropical North Pacific. Nitta (1987) found that, during the years of warm SST anomalies over the western Pacific, the intense convective regions are shifted to the south of

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Christoph W. Schmidt and Robert A. Goler

atmospheric layers with waves at its leading edge ( Simpson 1997 ). Two cases from Clarke (1986) were shown to be produced from thunderstorm outflows, while the remaining five cases were associated with an approaching cold front. Clarke (1986 , p. 74) notes that, as a cold front encounters the stably stratified marine inversion, it may “produce a bore, which in time may become undular, and eventually decay to a train of solitary waves.” Clarke (1986) also indicated the possibility that the cold front

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Lawrence C. Gloeckler and Paul E. Roundy

and ER waves, we assess feedbacks between the tropics and extratropics, with the MJO and ER waves both forcing and being forced by the extratropical circulation. 2. Data and methodology a. Data and compositing technique The National Oceanic and Atmospheric Administration (NOAA) interpolated outgoing longwave radiation (OLR) data ( Liebmann and Smith 1996 ) and the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis 300-hPa geopotential

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