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Anthony C. Hirst

exchange)are parameterized by Newtonian cooling. Results presented here generally have the cooling coefficient, B,set equal to A. Solutions where B ~ ,4 were found tobe qualitatively similar to those when B = `4 and arenot presented in detail. Standard values adopted herefor model coefficients are summarized in Table 1.b. The ocean 1) MODEL DEVELOPMENT The basic ocean model consists of a mixed layeroverlying a deep, cold, quasi-motionless layer. An infinitesimally thin thermocline separates the two

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Duane E. Waliser, Zhenzhou Zhang, K. M. Lau, and Jae-Hoon Kim

to SST warming in the east Pacific due to a suppression of the local thermocline (e.g., Lau and Chan 1988 ; Zebiak 1989 ; Weickmann 1991 ; Kessler et al. 1995 ; Moore and Kleeman 1999 ). The recent 1997/98 El Niño appears to be a particularly illustrative example of the interaction between MJO-related surface wind forcing and the development of an El Niño ( McPhaden 1999 ). In this same context, there is even an indication that intraseasonal forcing may impart a nontrivial influence on the

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Susan Kemball-Cook, Bin Wang, and Xiouhua Fu

1. Introduction The intraseasonal oscillation (ISO) makes up a large fraction of the observed tropical intraseasonal variability. The ISO is a large-scale, generally eastward-propagating disturbance in the tropical circulation and convection with a period of approximately 30–60 days ( Madden and Julian 1994 ). Recent observational and modeling studies have suggested that interactions between the ocean and the atmosphere occur on intraseasonal timescales and, further, that these interactions may

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Timothy J. Dunkerton and David C. Fritts

based upon turbulent eddy diffusion. Instead, the total wave plus mean flow pro~e, when required,is frictionally relaxed to a convectively neutral equilibrium which conserves potential temperature and tota~vorticity, analogous to the familiar "convective adjustment" procedure in general circulation models. Despitebeing a local adjustment within the wave, this turbulence parameterizafion seems to confirm the amplitudelimiting effects predicted by Lindzen's global amplitude balance model in the

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R. Lee Panetta

distance FIG. 6. Time (2000-3200) and zonal averages for the long experiment: in (a), (c), and (d), solid curves give upper-layer values, anddashed give lower; dotted lines indicate imposed values. Distances are in Rossby radii. In (b), the heat flux curve is solid and the temperaturegradient is dot-dashed. In (e) and (f), momentum flux convergence curves are solid, mean meridional circulation curves are dashed, smallscale mixing curves are dotted, and the Ekman drag curve is dot-dashed. In (g

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Enver Ramirez, Pedro L. da Silva Dias, and Carlos F. M. Raupp

-scale variability ( Inness 2002 ; Stevens and Bony 2013 ; Bony et al. 2015 ). There are also both observational (e.g., Johnson et al. 1999 ) and general circulation modeling (e.g., Inness et al. 2001 ) evidence of the modulation of weather-scale phenomena by climate variability. In addition, because of the large gap between weather and climate time scales, if the weather affects the climate, this connection ought to be through multiscale interaction mechanisms. Thus, a renewed interest in systematic methods

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J. C. McWilliams and P. R. Gent

. Part 2. Application to sea surface temperatureanomalies and thermocline variability. Tellus, 29, 289-305.Hasselmann, K., 1976: Stochastic climate models. Part 1. Theory.Tellus, 28, 473-485.Julian, P. R., and R. M. Chervin, 1978: A simulation of theSouthern Oscillation and the Walker Circulation. Submittedto Mon. Wea. Rev.,Knauss, J. A., 1963: Equatorial current systems. Th~ Sea, Vol. 2,Interscience, 235-252.(Bill Kung, E. C., 1967: Diurnal and long-term variations of the-kinetic' / energy

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Joseph J. Barsugli and David S. Battisti

mathematical or statistical model. At the complex end of the modeling spectrum, studies using realistic atmospheric general circulation models (AGCMs) have been used to examine the impacts of coupling on the natural climate variability in the midlatitudes (e.g., Schneider and Kinter 1994 ; Manabe and Stouffer 1996 ; Lau and Nath 1996 ; Bhatt et al. 1998 ; Bladé 1997 ; Nitsche 1996 ). The methodology used in each of these studies involves the comparison of two integrations of the AGCM. First, the AGCM

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R. L. Walterscheid and G. Schubert

from theturbulence model of wave saturation have no rigorous justification and could give erroneous results if employedin studies of middle atmosphere circulation and minor constituent mixing. The immediate consequence ofwave overturning is small-scale convection (regular, cellular structures with length scales of several to tens ofkilometers) in the moving unstable phases of the wave. Cellular convection grows at the expense of the waveand provides a stabilization of the gross stratification

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R. T. Pierrehumbert and H. Yang

discussed in a separate paper. We conclude with a few remarks putting the mixingresults in context within the broader setting of the general circulation. The approach that is emerging is similar to that extant in ocean thermocline theory, withthe 315-K isentropic surface regarded as being "ventilated'' in the tropics (see, e.g., Hoskins 1989). In thepresent terrestrial climate, the northern extratropicshave generally high positive potential vorticity on the315-K surface, the southern extratropics

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