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Volkmar Wirth and Timothy J. Dunkerton

hurricane the eye secondary circulation must be mechanically forced ( Emanuel 1997 ). Both Smith (1980) and Emanuel (1997) refer to turbulent exchange of angular momentum across the eyewall when talking about mechanical forcing. By contrast, the hurricane theory of Emanuel (1986) is effectively inviscid in the interior of the atmosphere, leaving Ekman pumping from the frictional boundary layer as the only possible source of mechanical forcing. The above quoted theoretical approaches are not

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Kaushik Srinivasan and W. R. Young

1. Introduction In this work we consider a canonical linear problem: the stochastically forced, linearized β -plane vorticity equation with a background mean shear γ : The eddy vorticity is related to the eddy streamfunction by , and the eddy velocities are . The random forcing ξ ( x , y , t ) is spatially homogenous and white noise in time and is characterized more precisely in section 2 . Drag, with coefficient μ , is the dissipative mechanism. Our main concern is the eddy transport

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Chih-Pei Chang

740 JOURNAL OF THE ATMOSPHERIC SCIENCES Vo~.u~aE33Forcing of Stratospheric Kelvin Waves by Tropospheric Heat Sources c~ra-P~ Cm~oDepartment of Meteorology, Na~al Postg~,aduate School, Monterey, Calif. 93940(Manuscript received 19 November 1975, in revised form 22 January 1976) The problem of scale-selection of Kelvin waves in the stratosphere by forcing from tropospheric heatingis analyzed using a

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Li Dong and Stephen J. Colucci

1. Introduction In a previous study, Dong and Colucci (2005 , hereafter referred to as DC2005 ) identified two mechanisms that each acted alone, but rarely in concert, to force the weakening of midtropospheric westerlies associated with the analyzed Southern Hemisphere (SH) blocking cases. These mechanisms are the advection of a meridional gradient in potential vorticity (PV), referred to hereafter as the advection forcing, and the interaction between deformation and the PV gradients

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Christopher M. Rozoff, James P. Kossin, Wayne H. Schubert, and Pedro J. Mulero

material rate of change of θ ρ , and F the frictional force per unit mass. It should be noted that (1) does not differ greatly from the PV equation for a dry atmosphere because the total density ρ is approximately equal to the dry air density and the virtual potential temperature θ ρ is approximately equal to the dry potential temperature. Based on (1) , we can say that there are three aspects to understanding the PV structure in hurricanes: (i) the advective aspects embodied in the D / Dt

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Joonsuk Lee, Ping Yang, Andrew E. Dessler, Bo-Cai Gao, and Steven Platnick

convective blowoff, whereas the other half were associated with in situ formation. Because of the high frequency of occurrence of thin cirrus clouds, the effect of these clouds on the earth’s radiation budget can be significant. For example, these clouds, located high in the atmosphere, absorb longwave radiation but emit radiation at very low temperatures, producing local heating by a few degrees per day ( Jensen et al. 1996 ; McFarquhar et al. 2000 ) and net positive cloud radiative forcing on the

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Wojciech W. Grabowski

others. However, in nature, convective clouds continuously interact with their surroundings through gravity waves and detrainment that modify their environment (e.g., Bretherton and Smolarkiewicz 1989 ). These interactions affect development of subsequent clouds. Thus, it is irrelevant what the first cloud does, but what matters is a response of an ensemble of clouds to realistic forcings averaged over many cloud realizations. (An exception to this argument might be when the first cloud causes a

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Junyan Xiong, Jun Yang, and Ji Nie

; for example, a doubling of atmospheric pressure produces a warming of ~7 K ( Charnay et al. 2013 ), and a pressure of 2.4 bar N 2 leads to surface warming of 9.7 K ( Wolf and Toon 2013 ). In this study, we mainly consider the scenario in which the atmospheric mass change is due to changes in the masses of radiatively inactive species (i.e., N 2 and O 2 ), thus excluding direct radiative forcing due to changes in the masses of radiatively active species. We explore the dependence of climate on

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Tiehan Zhou, Marvin A. Geller, and Wuyin Lin

velocity on a given pressure level is controlled exclusively by the distribution of the wave drag above that level. The downward control principle ( Haynes et al. 1991 ) is conventionally formulated as where is the residual mean vertical velocity, φ the latitude, z the log pressure height, ρ 0 the reference density profile, a the radius of the earth, D the wave forcing, the zonal mean angular momentum, the zonal mean zonal wind, Ω the angular velocity of the earth, and dz ′ the

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Rolando R. Garcia and John E. Geisler

OCTOBER 1981 ROLANDO R. GARCIA AND JOHN E. GEISLER 2187Stochastic Forcing of Small-Amplitude Oscillations in the Stratosphere ROLANDO R. GARCIA AND JOHN E. GEISLER~National Center for Atmospheric Research? Boulder, CO 80307(Manuscript received 12 March 1981, in final form 11 May 1981)ABSTRACT A quasi-geostrophic/g-plane channel model is used to study the response of the stratosphere to planetarywaves forced at the

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