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Timothy Andrews and Mark A. Ringer

1. Introduction a. Conceptual framework The earth’s energy balance provides a convenient framework for understanding the global response of the climate system to natural and anthropogenic forcings. During transient climate change, the global surface air temperature change Δ T (K) is determined by forcing, feedback, and heat uptake processes. These quantities can be related through a simple linear relationship whereby the net heat flux into the climate system N (W m −2 )—which is

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Bruce T. Anderson, Jeff R. Knight, Mark A. Ringer, Jin-Ho Yoon, and Annalisa Cherchi

extreme precipitation ( Zhang et al. 2007 ; Min et al. 2009 ); atmospheric humidity ( Santer et al. 2007 ; Willett et al. 2010 ); and streamflow ( Hidalgo et al. 2009 )—are consistent with increased anthropogenic emissions of greenhouse gases and aerosols and inconsistent with other known forcing agents, including solar and volcanic activity ( Barnett et al. 2005 ; Solomon et al. 2007 ). However, such consistency does not preclude the possible influence of other unknown forcing agents ( Stone et al

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S. J. Ghan, X. Liu, R. C. Easter, R. Zaveri, P. J. Rasch, J.-H. Yoon, and B. Eaton

1. Introduction Anthropogenic aerosol is thought to play an important role in driving climate change, but its role is so complex that uncertainty in estimates of radiative forcing of climate change is dominated by uncertainty associated with forcing by anthropogenic aerosol ( Forster et al. 2007 ). This complexity arises because anthropogenic aerosol alters the planetary energy balance through a variety of mechanisms operating across a wide range of spatial scales: direct effects ( Haywood and

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Reinout Boers, Fred Bosveld, Henk Klein Baltink, Wouter Knap, Erik van Meijgaard, and Wiel Wauben

Experiment (ERBE) and the Clouds and the Earth’s Radiant Energy System (CERES). Both datasets provide top-of-atmosphere (TOA) radiative fluxes that can be used to evaluate the model cloud representation or to determine the impact of clouds on the radiation balance of Earth. An often used method to determine cloud impact is to measure cloud forcing, which is defined as the difference between the net all-sky and the net clear-sky radiant fluxes ( Charlock and Ramanathan 1985 ). However, TOA fluxes only

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E. J. Rohling, M. Medina-Elizalde, J. G. Shepherd, M. Siddall, and J. D. Stanford

1. Introduction Records of palaeoclimate change through glacial cycles in the recent geological past provide important observational evidence concerning the climate response to changes in radiative forcing (e.g., Hansen et al. 2007 , 2008 ; Köhler et al. 2010 ; Masson-Delmotte et al. 2010a ). However, uncertainties remain regarding important variables, such as temperature responses, the amplitude and causes of polar amplification, and about the magnitude of radiative forcing changes on

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Michael P. Erb, Anthony J. Broccoli, Neal T. Graham, Amy C. Clement, Andrew T. Wittenberg, and Gabriel A. Vecchi

-day eastern equatorial Pacific sea surface temperature (SST) cycle is characterized by maximum warmth in boreal spring and minimum warmth in boreal summer and autumn. Farther west, near the date line, the seasonal cycle is weaker, with the warm peak occurring a month or two later in the year. West of 160°E there is a semiannual cycle, with warm peaks in April–May and in November. Because tropical insolation forcing is semiannual, with maxima near the two equinoxes, the eastern equatorial Pacific SST cycle

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Yunfeng Cao, Shunlin Liang, Xiaona Chen, and Tao He

. Two recent typical studies based on satellite retrievals show large differences from one another. Flanner et al. (2011) used a synthesis of calculated sea ice albedo, with sea ice type derived from sea ice concentration and in situ measurements of sea ice albedo, and radiative kernels to estimate the sea ice radiative forcing (SIRF) in the Northern Hemisphere (NH). They found the change in SIRF from 1979 to 2008 was 0.22 (0.15–0.32) W m −2 , and the corresponding SIAF was 0.28 (0.19–0.41) W m −2

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Courtenay Strong and Gudrun Magnusdottir

1. Introduction The response of atmospheric general circulation models to boundary forcing is quite varied across models and experiments ( Kushnir et al. 2002 ) and has been challenging to interpret because of nonlinearities with respect to the sign of the forcing anomaly ( Kushnir and Lau 1992 ; Peng et al. 2002 , 2003 ; Ferreira and Frankignoul 2005 ) and the location of the forcing anomaly relative to the storm track ( Peng et al. 1997 ). Despite these complexities, studies of transient

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Thomas B. Richardson, Piers M. Forster, Timothy Andrews, and Doug J. Parker

1. Introduction Regional precipitation change is one of the most uncertain aspects of climate change prediction ( Stephens et al. 2010 ; Liepert and Previdi 2012 ; Stevens and Bony 2013 ) and can have major societal implications ( Wake 2013 ). On a global scale, the precipitation response to a forcing can be understood through atmospheric energy budget arguments ( Mitchell et al. 1987 ; Allen and Ingram 2002 ; O’Gorman et al. 2012 ). Tropospheric radiative cooling tightly constrains global

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Amato T. Evan, Gregory R. Foltz, and Dongxiao Zhang

. 2009 ) or the top of the atmosphere ( Evan and Mukhopadhyay 2010 ). Therefore, by bulk formulas, the presence of an elevated aerosol layer over water would tend to cool the ocean. Schollaert and Merrill (1998) showed a negative correlation between individual dust outbreaks and underlying SST and used a mixed-layer heat budget analysis to suggest that the magnitude of the aerosol direct effect was sufficiently large to force the observed cool anomalies. Evan et al. (2008) demonstrated that on

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