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Yanping Li and R. E. Carbone

frequent. Largely overlooked is the potential significance of mesoscale solenoidal circulations as a deterministic mechanism for excitation of oceanic rainfall events. Below, we briefly discuss analogous forcings over continents, tropical islands, and western boundary current regions, followed by a selective summary of literature directly relevant to Pacific warm pool conditions. a. Background It is well known that lower-boundary forcing is one of the most influential factors governing the occurrence

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R. Kleeman

tropical precipitationand circulation anomalies observed during various E1 Nifio and La Nifia events. The dynamical part of themodel is a linearization about a state of rest with the usual tropical vertical mode retained. The heating isobtained from latent and nonlatent sources with the former obtained from perturbing a steady-state moistureequation about climatology and confining the heating to high SST regions. A thorough sensitivity analysis isundertaken and the model tendency to place major

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K. Shafer Smith

1. Introduction Explanations of the basic features of Jovian circulation have ranged from deep convective rolls to baroclinic instability. Recently, based on analysis of data from the Galileo satellite, Gierasch et al. (2000) and Ingersoll et al. (2000) have argued that small-scale shallow convection from internally generated heat is widespread and likely represents the largest source of energy to the circulation. The organizing principle invoked is that of an inverse cascade of energy in

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Hongyan Zhu, Wolfgang Ulrich, and Roger K. Smith

surface wind stress also generates ocean currents and strong turbulent mixing in the ocean. The mixing deepens the ocean mixed layer, entraining cooler thermocline water into it, which in turn lowers the SST. Observations show that the maximum SST reduction lies between 1° and 6°C, depending on the translation speed of the cyclone ( Black 1983 ). The cooling reduces the degree of thermal disequilibrium across the air–sea interface, or may even reverse the heat and moisture fluxes across the interface

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Maarten Ambaum

, cutting the atmospheric boundary layer, relaxes toward a zero potential vorticity state. This mechanism is analogous to that of the ventilated thermocline in the ocean, where an isopycnic surface cuts the turbulent boundary layer (e.g., Woods 1985 ), though in this process the local net mass flux is generally not equal to zero. Hoskins (1991) remarks in his article on the PV- θ view of the general circulation that the lowest isentrope of the Middleworld usually grazes the earth’s surface in the

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Richard Rotunno

, statistics, and spectral dy namics. University of Tennessee Space Institute, S/w. rt Course o~ Turbulsnce (in press). , and J. L. Lumley, 1972: A First Course in Turbulence. The MIT Press, 300 pp.Woods, J. D., 1974: Space-time characteristics of turbulence in the seasonal thermocline. M~m. Soc. Roy. Sci. Liege, 6th ser., 6, 109-130. , 1975: The local distribution in Fourier space/time of variability associated with turbulence in the seasonal thermo cline. M~m. Soc. Roy. Sci. Lidge, 6th ser., 7

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Tianming Li

) boundary-layer model. It allows active interactions between free-atmosphere circulations driven by convective heating and boundary-layer flows driven by SST gradients. The basic state of the model atmosphere is a motionless, thermodynamic-equilibrium state that overlies a uniform SST distribution. The governing equations of the 2½-layer model can be written as where ( U L , V L ) and ( U B , V B ) stand for the lower-troposphere and boundary-layer wind components, ϕ stands for the lower

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H. Nuzhet Dalfes, S. H. Schneider, and Starley L. Thompson

in our basecase (az~ = 0.32 K).6: Discussion and conclusions We can turn to general circulation model simulations for aid in estimating the fraction of observedclimatic variability that is due to stochastic weatherfluctuationS. We chose to examine a few coupled atmosphere/ocean GCMs which have been run for atleast several simulated years. Manabe and Stouffer(1980) at GFDL, using a realistic geography and a,~u I00tatz i0-~010-3 I0-$i iiiiiiiI i i iiiiii - Base Experiment

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Álvaro Viúdez, Joaquín Tintoré, and Robert L. Haney

the PEcounterpart of the QG differential vorticity equation. The generalized equations also show the role that the rateof change of differential ageostrophic vorticity and differential divergence play in forcing nonquasigeostrophicvertical velocity and nonquasigeostrophic vorticity, respectively. This is illustrated by a simple application ofthe theory for the circulation in a tropical cyclone. Finally, the necessary and sufficient conditions required toobtain the corresponding QG expressions are

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Rameshan Kallummal and Ben P. Kirtman

conditions is examined based on a linear model estimated using the data from an anomaly coupled ocean–atmosphere general circulation model ( ACGC M). The studies mentioned in the previous paragraph emphasized that a most useful diagnostic tool for this purpose is the optimals. However, the majority of the earlier studies used either simple models or models of intermediate complexity in which the atmospheric dynamics was drastically simplified. Moreover, there was considerable disagreement among these

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