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Virendra P. Ghate, Bruce A. Albrecht, Christopher W. Fairall, and Robert A. Weller

lack of direct observations for the verification and evaluation of model representations of this region. In this study we present climatology of the SEP region using data from the Stratus ORS, collected during January 2001 to December 2005. The annual cycle of the surface meteorological parameters and surface fluxes is presented in section 2 . Cloud fraction is determined using a simple model in section 3 . Annual and diurnal changes in the cloud radiative forcing are discussed in section 4

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Nicholas Lewis and Judith Curry

, their claims are based on comparing temperature changes in historical simulations by CMIP5 climate models and observations and not on comparing the ratio of temperature and forcing changes (on which ratio LC18 ’s TCR estimation is based) in CMIP5 models with that in observations. The two types of comparisons are equivalent only if forcing in CMIP5 models on average evolves identically to its estimated actual evolution. This is not the case, and therefore these two approaches are not equivalent

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Andrés Antico, Olivier Marchal, Lawrence A. Mysak, and Françoise Vimeux

1. Introduction Long-term variations in the geometry of Earth’s orbit around the Sun produce changes in the incoming solar radiation (i.e., insolation), which is the main external forcing of the climate system. These variations consist of the precession of the equinoxes (dominant periods of 19 and 23 kyr), obliquity cycles (41 kyr), and eccentricity cycles (100 and 400 kyr). The resulting insolation cycles are known as Milankovitch forcing (see Loutre et al. 2004 and Crucifix et al. 2006

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Matthew R. Mazloff, Raffaele Ferrari, and Tapio Schneider

-dimensional pathways of ocean water masses. Here we use a synthesis of observations, a numerical model, and theory to investigate the force balance of the SO limb of the MOC. Standard scaling analysis for the large-scale ocean circulation assumes a small Rossby number, leading to the thermocline equations based on the linearized planetary geostrophic equations ( Robinson and Stommel 1959 ; Welander 1959 ; Phillips 1963 ; Pedlosky 1987 ). But in the Drake Passage latitude band of the SO, at depths where there

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Martin P. King, Fred Kucharski, and Franco Molteni

significance level cannot be evaluated rigorously because, necessarily, there is only a single realization of the observed trend. The significance is calculated based on the decadal variance for December–March (DJFM). In any case, the present study focuses on the North Atlantic sector, where there is an exceptionally strong trend, providing a signal of high significance. The connection between tropical SST forcing and extratropical circulation changes has received considerable attention (e.g., Bader and

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Michael A. Spall

transport, downwelling transport, and density of convective waters and exported waters formed in a marginal sea subject to specified buoyancy forcing can be obtained from the environmental parameters by making use of geostrophic balance, mass balance, heat balance in the basin interior, and heat balance in the marginal sea ( Spall 2004 ; Straneo 2006 ; Iovino et al. 2008 ). A key step in this formulation is that the interior of the marginal sea is not connected to the open ocean along geostrophic

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Timothy Andrews, Jonathan M. Gregory, and Mark J. Webb

1. Introduction Earth’s global energy balance provides a convenient framework for describing and predicting climate change. Changes to this balance caused by an external factor are termed “radiative forcings” (e.g., Shine and Forster 1999 ). The magnitude of climate change in response to a radiative forcing is determined by heat uptake and various climate feedbacks that amplify or dampen the initial perturbation, such as changes in clouds, sea ice, and water vapor (e.g., Soden and Held 2006

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Allan J. Clarke

zonal thermocline depth. The “disequilibrium” is associated with anomalous WWV both leading and lagging standard ENSO indices by about a quarter of the period of the oscillation. This amounts to a lag of several months on ENSO time scales and, for decadal periodicity, about 2–3 yr ( Hasegawa and Hanawa 2003a ). One might expect rapid ocean adjustment to wind forcing near the equator where equatorial Kelvin and Rossby waves propagate quickly. If so, then why should there still be such large lags

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Xuebin Zhang and Michael J. McPhaden

the positive air–sea feedback was the variation of equatorial upwelling associated with variations in the easterly trade winds. He hypothesized that it was the local winds in the eastern Pacific that were important, though since then we have learned that it is remote wind forcing from the central and western Pacific that is dominant in the evolution of El Niño and La Niña (e.g., Wyrtki 1975 ; Neelin et al. 1998 ). Nonetheless, interest has grown recently in the possible role of local wind

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James R. Campbell, Simone Lolli, Jasper R. Lewis, Yu Gu, and Ellsworth J. Welton

1. Background Cirrus clouds have long been recognized for their unique contribution to climate ( Liou 1986 ). In particular, whereas all clouds warm the underlying atmosphere and surface at night [positive top-of-the-atmosphere (TOA) forcing], cirrus is the only genus that can readily warm or cool (negative TOA forcing; effectively all other clouds cool the daytime atmosphere) the daytime atmosphere and surface depending on the cirrus’s varying physical characteristics [i.e., cloud height

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