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Thomas Griesser, Stefan Brönnimann, Andrea Grant, Tracy Ewen, Alexander Stickler, and Joey Comeaux

present statistical reconstructions of GPH and temperature for three regions: the Northern Hemisphere (NH; 15°–90°N), the tropics (TP; 20°S–20°N), and the Southern Hemisphere (SH; 15°–90°S). The dataset consists of monthly reconstructions on the levels 850, 700, 500, 300, 200, and 100 hPa for the period 1880–1957 to allow for a seamless connection to the ERA-40 reanalysis. Note that we propose to use the regions separately where possible. Global fields can be produced by using a linear combination in

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Richard Seager, Amy C. Clement, and Mark A. Cane

( Bard et al. 1997 ), which suggests a quite uniform 2-K cooling in the Tropics. However, other recent estimates, based on geochemical analyses of Sr/Ca ( Guilderson et al. 1994 ) and noble gases ( Stute et al. 1995 ) indicate much larger coolings of as much as 5 K. Also, while some oxygen isotope data seem to agree with the CLIMAP estimates, it has been argued that allowing for pore water ice volume ( Schrag et al. 1996 ) and pH ( Spero et al. 1997 ) influences brings these data more in line with

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Ori Adam and Nathan Paldor

1. Introduction Axially symmetric models that describe the zonally averaged general circulation of the atmosphere are most relevant to the tropics where a weak Hadley circulation is produced even when large-scale eddies are suppressed. Poleward of the tropics, macroturbulent and moist momentum heat fluxes dominate those of the mean circulation and, therefore, significantly influence the circulation strength and width and the meridional profile of the subtropical jet. Macroturbulent and moist

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Alison D. Nugent, Ronald B. Smith, and Justin R. Minder

either smooth stratiform or turbulent convective clouds. The latter is more common in the tropics as conditional instability is common in the lower free troposphere. Numerical studies have examined how various parameters affect the strength and organization of mechanically forced convection over an isolated mountain (e.g., Tian and Parker 2002 ; Fuhrer and Schär 2005 ; Kirshbaum and Durran 2005 ; Miglietta and Rotunno 2009 ). These parameters have included the height and shape of the mountain

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Michiya Hayashi and Hisanori Itoh

tropics and extratropics, its mechanism is still debated. In particular, the cause for the slow eastward phase propagation of about 5 m s −1 is still unsettled. Numerous previous studies have attempted to explain the slow eastward propagation of the MJO in terms of convectively coupled equatorial Kelvin waves or internal gravity waves (e.g., Lau and Peng 1987 ; Takahashi 1987 ; Chang and Lim 1988 ; Yoshizaki 1991 ). Theories based on the wind-induced surface latent heat flux were invoked to

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Gang Hong, Ping Yang, Bo-Cai Gao, Bryan A. Baum, Yong X. Hu, Michael D. King, and Steven Platnick

1. Introduction High clouds occur frequently over the Tropics (e.g., Liou 1986 ; Rossow and Schiffer 1999 ; Wylie et al. 1994 , 2005 ; Liu et al. 1995 ; Wang et al. 1996 , 1998 ; Wylie and Menzel 1999 ; Dessler and Yang 2003 ; Luo and Rossow 2004 ; Stubenrauch et al. 2006 ). The effect of high clouds on the climate system is highly sensitive to their optical and microphysical properties (e.g., Stephens et al. 1990 ; Liu and Curry 1999 ; McFarquhar et al. 2002 ). Cloud

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Prashant D. Sardeshmukh and Brant Liebmann

VOLUME 6JOURNAL OF CLIMATEAPRIL 1993 An Assessment of Low-Frequency Variability in the Tropics as Indicated by Some Proxies of Tropical Convection PRASHANT D. SARDESHMUKH AND BRANT LIEBMANNCooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, Colorado(Manuscript received 25 September 1991, in final form 29 May 1992)ABSTRACT Any discussion of intraseasonal and interannual variability in the atmosphere must presume a reliable assessment

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George Tselioudis and William B. Rossow

makes it hard to synthesize them into a comprehensive description of the variability of the whole tropics and to quantify at planetary scales the changes in tropical cloud, radiation, and precipitation between the different modes of variability. Given that in a climate change situation, radiative and hydrologic feedbacks can result from subtle changes in the frequency of the primary variability regimes (e.g., Bony et al. 2006 and references therein), it is important to derive a global baseline of

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Clara Deser, Adam S. Phillips, and James W. Hurrell

–tropical interactions via an equatorward subsurface oceanic pathway and a return atmospheric bridge ( Gu and Philander 1997 ; Deser et al. 1996 ; Schneider et al. 1999 ); and climate noise due to the integrating effect of stochastic atmospheric variability by the North Pacific Ocean mixed layer ( Pierce et al. 2001 ; Newman et al. 2003 ) and the thermocline ( Frankignoul et al. 2000 ). Note that the Tropics play an active role in some theories but not in others. What do observational studies indicate about the

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J. Teixeira, S. Cardoso, M. Bonazzola, J. Cole, A. DelGenio, C. DeMott, C. Franklin, C. Hannay, C. Jakob, Y. Jiao, J. Karlsson, H. Kitagawa, M. Köhler, A. Kuwano-Yoshida, C. LeDrian, J. Li, A. Lock, M. J. Miller, P. Marquet, J. Martins, C. R. Mechoso, E. v. Meijgaard, I. Meinke, P. M. A. Miranda, D. Mironov, R. Neggers, H. L. Pan, D. A. Randall, P. J. Rasch, B. Rockel, W. B. Rossow, B. Ritter, A. P. Siebesma, P. M. M. Soares, F. J. Turk, P. A. Vaillancourt, A. Von Engeln, and M. Zhao

tropics and subtropics and to characterize the main deficiencies in climate models in terms of the representation of clouds and cloud-related processes. These analyses should lead to the development of new parameterizations of clouds, boundary layer, and convection and consequently contribute to more accurate predictions of climate change. Ultimately, it is the combination of the model and the satellite data and the use of new analysis techniques that will improve our ability to not only establish the

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