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Xun Zhu and James R. Holton

620 JOURNAL OF THE ATMOSPHERIC SCIENCES VOL. 44, No. 3Mean Fields Induced by Local Gravity-Wave Forcing in the Middle Atmosphere XUN ZHU AND JAMES R. HOLTON Department of Atmospheric Sciences, University of Washington, Seattle. WA 98195 (Manuscript received 29 May. 1986, in final form 25 September 1986) ABSTRACT We examine the role ofgeostrophic adjustment in the middle

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F. J. Robinson, S. C. Sherwood, D. Gerstle, C. Liu, and D. J. Kirshbaum

observational limitations. For example, storm development is very sensitive to environmental conditions that are hard to measure such as flow divergence, small-scale details at low levels (e.g., Wakimoto and Murphey 2008 ; Wilson and Schreiber 1986 ), or small variations in convective instability ( Lima and Wilson 2008 ). More fundamentally, chaotic turbulent phenomena can be expected to evolve differently over time even with nearly identical initial conditions and forcings. Finally, important storm

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Yizhe Peggy Bu, Robert G. Fovell, and Kristen L. Corbosiero

differ with respect to the amounts and relative distributions of hydrometeors, such as cloud ice, snow, cloud droplets, etc. ( Fovell et al. 2010b ). These particles have different effective sizes that determine how they interact with longwave (LW) and shortwave (SW) radiation (e.g., Dudhia 1989 ). Herein, we demonstrate how and why cloud–radiative forcing (CRF), the modulation of atmospheric radiation owing to hydrometeors, can influence tropical cyclones. The specific focus is on storm structure

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Fenwick C. Cooper and Peter H. Haynes

1. Introduction The prediction of the response of the climate system to an external forcing or to a change in some parameter of the system is seen as a key problem in climate science. It is an example of the general mathematical problem of predicting the change in a dynamical system, for example, the change in the probability density function (PDF) of the system as manifested by changes in selected observables, as a response to a change in the parameters of the system. In a broad class of

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Nikki C. Privé and R. Alan Plumb

flow at low levels. Using a linear shallow-water model, Gill (1980) found that a localized prescribed forcing in the off-equatorial Tropics induces a cross-equatorial circulation similar to the observed monsoon flow. However, Held and Hou (1980) , Lindzen and Hou (1988) , and Plumb and Hou (1992) determined the axisymmetric Hadley circulation to be fundamentally nonlinear, and predicated upon the conservation of angular momentum in the free troposphere. The intent of this work is to explore

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Michael J. Ring and R. Alan Plumb

substantial components of atmospheric variability, these patterns have come to be known as “modes.” But is this a meaningful description? If these patterns are truly mode-like, then not only will they appear as unforced natural variability, but also as a preferred response of the atmospheric circulation to external forcings. There are indeed suggestions of such a preferred response in the atmosphere to Antarctic ozone depletion ( Thompson and Solomon 2002 ) and greenhouse forcing (e.g., Shindell et al

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Jong-Jin Baik, Hong-Sub Hwang, and Hye-Yeong Chun

one region to another, and the triggering of instabilities that cause severe convective systems to develop ( Hooke 1988 ). There are several numerical modeling studies to examine the role of gravity waves in the circulation that develops around diabatic forcing. Yang and Houze (1995) suggested that the multicellular structure of a midlatitude squall line is associated with gravity waves generated by convection. Pandya and Durran (1996) showed that the transient response of gravity waves

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Masaru Inatsu, Hitoshi Mukougawa, and Shang-Ping Xie

zonal asymmetry in the Northern Hemisphere winter climate. The forcing lies ultimately on earth's surface: large-scale mountains, zonal variations in sea surface temperature (SST), and land–sea distribution. Their relative importance for stationary eddies has been mainly investigated by linear models. Charney and Eliassen (1949) and Smagorinsky (1953) pioneered the study of the linear response to orographic and extratropical thermal forcing, while tropical thermal forcing is emphasized by

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Marvin A. Geller, Weixing Shen, Minghua Zhang, and Wei-Wu Tan

suggested that the waves responsible for forcing the QBO were the equatorial Kelvin and mixed Rossby–gravity waves. Research on this topic has progressed since the papers of LH and HL to include two- and three-dimensional models of the QBO (e.g., Plumb and Bell 1982; Takahashi and Boville 1992) and to include forcing by a spectrum of waves ( Saravanan 1990 ). Both observational analysis ( Lindzen and Tsay 1975 ) and three-dimensional modeling ( Takahashi and Boville 1992 ) indicate that the easterly

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Jianchun Qin and Walter A. Robinson

15NOVEMBER 1995 QIN AND ROBINSON 3895The Impact of Tropical Forcing on Extratropical Predictability in a Simple Global Model JIANCHUN QINClimate Analysis Center, NOAA/NWS/NMC, Camp Springs, Maryland WALTER A. ROBINSONDepartment of Atmospheric Sciences, University of lllinois, Urbana, Illinois(Manuscript received 20 January 1994, in final form 9 May 1995)ABSTRACT The impact of

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