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Jun-Mei Lü, Seong-Joong Kim, Ayako Abe-Ouchi, Yongqiang Yu, and Rumi Ohgaito

the AO, such as stratosphere–troposphere interactions, eddy-mean flow feedback, and planetary wave activity, have been proposed ( DeWeaver and Nigam 2000 ; Saito et al. 2001 ; Chen and Huang 2005 ; Lü et al. 2008 ). According to the theory of wave-mean flow interaction ( Andrews et al. 1987 ), when planetary wave activity is weak in the middle latitude stratosphere, the decline of dynamic adiabatic heating in polar cap regions leads to a decrease in temperature, the increase of meridional

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Yosef Ashkenazy and Eli Tziperman

to the stability threshold to suggest that the snowball circulation may be brought by the eddy-mean flow interaction to near a marginally stable state, as is often claimed to be the case for the present-day ocean and atmosphere (e.g., Farrell and Ioannou 1995 ; Jansen and Ferrari 2012 ). To further analyze the possible occurrence of barotropic instability, we numerically solved the Rayleigh equation ( Vallis 2006 ): where u is the zonal mean of the zonal current in our GCM solutions at

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Bohua Huang, Paul S. Schopf, and J. Shukla

Mayer 1997 ). The present experiment suggests that the spatial pattern of the NTA is mainly determined by ocean–atmosphere coupling within the Atlantic Ocean. The effect of ENSO may be primarily to modulate the temporal evolution of the NTA through influencing atmospheric planetary waves influencing the Atlantic basin. More recently, a more comprehensive study was presented by Huang (2003) , which examined an ensemble of eight regional coupled runs with the observed SST forcing for 1950–98. Apart

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James B. Pollack, David Rind, Andrew Lacis, James E. Hansen, Makiko Sato, and Reto Ruedy

volcanic aerosol forcing. These climatic changes arecompared with those obtained with the same climate model when the CO2 content of the atmosphere wasdoubled (2>(CO2) and when the boundary conditions associated with the peak of the last ice age were used( 18 K). In all three cases, the absolute magnitude of the change in the globally averaged air temperature at thesurface is approximately the same, ~5 K. The simulations imply that a significant cooling of the troposphere and surface can occur at

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Wojciech W. Grabowski

1. Introduction Clouds and their impact on the transfer of solar (shortwave) and earth’s thermal (longwave) radiation are the most challenging aspects of climate and climate change (e.g., Stephens 2005 , and references therein). This is because of the enormous range of spatial and temporal scales involved, from a fraction of a millimeter (e.g., growth of cloud droplets and ice particles) to planetary (e.g., synoptic disturbances in midlatitudes and Hadley and Walker circulations in the Tropics

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Neal Butchart, John Austin, Jeffrey R. Knight, Adam A. Scaife, and Mark L. Gallani

domain has been extended to allow for a more comprehensive treatment of the middle atmosphere (e.g., see Hamilton 1996 ). However, only a few of these extended models (e.g., Mahfouf et al. 1994 ; Rind et al. 1998 ) have been used in estimating the future state of the stratosphere. Therefore, additional simulations are required to determine with confidence the likely atmospheric changes. In this paper we present new predictions obtained from the troposphere–stratosphere configuration of the U

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Yongkang Xue, F. de Sales, W-P. Li, C. R. Mechoso, C. A. Nobre, and H-M. Juang

a 5-month period corresponding to the northern warm season of 1987 that differ in the initial conditions for the atmosphere but have the same initial conditions in soil moisture and similar monthly mean surface albedo and roughness length. The two ensembles produced similar results at the planetary scale but substantially different results in the monsoon regions and some continental areas. In GCM/Soil, the moisture transport and precipitation were too strong in the premonsoon season, and the

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Rong Fu, Anthony D. Del Genio, and William B. Rossow

analyze the influence of sea surface temperature (SST) and surface wind divergence on atmosphericthermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983July 1985. The onset ofdcep convection requires not only the existence of positive convective available potentialenergy (CAPE), but also an unstable planetary boundary layer (PBL). A stable PBL is

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Rong Fu, Bin Zhu, and Robert E. Dickinson

. The GEOS-1 reanalysis data ( Schubert et al. 1993 ) are used for monthly and daily mean temperature, humidity, the pressure at the surface and in the atmosphere, the lower-tropospheric winds, the moisture transport and convergence, and geopotential height at 200 mb to provide diagnoses of large-scale thermal and dynamic properties of the atmosphere and land surface. A simple slab mixed-layer model ( Tennekes 1973 ; Betts 1973 ) helps infer the temperature and humidity in the afternoon planetary

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John M. Wallace, Catherine Smith, and Christopher S. Bretherton

modes more closelyresemble the patterns derived from PCA of the 500-mb height field than those for the SVD modes on whichthey are based. The SVD and CPCA solutions for the first three modes proved to be quite similar.The SVD and CCA solutions based on the hemispheric 500-mb height field are indicative of a couplingbetween the interannual variability of North Pacific and North Atlantic SST by virtue of their mutual relationshipto one of the atmosphere's most prominent planetary wave patterns.1

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