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Joel R. Norris and Amato T. Evan

subgrid-scale cloud processes and produce cloud simulations that are inconsistent with one another and with observations (e.g., Clement et al. 2009 ; Klein et al. 2013 ). The shortcomings of theory and global climate models motivate the alternative approach of observing how clouds have changed in recent decades, a time period of rapidly increasing anthropogenic forcing and warming of the climate system. If patterns of multidecadal cloud variability likely to be associated with anthropogenically

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James R. Drummond and G. S. Mand

also be assimilated into 3D models to study the chemistry anddynamics of the lower atmosphere. Carbon monoxide is a relatively short-lived gas (3months) in the troposphere and is thus susceptible toatmospheric transport phenomena without completelymixing; it exhibits a 3-to-1 interhemispheric surfacedifference [50-150 ppbv, Logan et al. (1981)]. Carbon monoxide profiles and column measurements willbe used to identify surface sources, natural and anthropogenic. The profile measurements will

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Joseph M. Ritter and Kenneth J. Voss

). Unfortunately, the global impact of aerosol optical effects are not well understood. In fact, the uncertainty in the aerosol radiative forcing is larger than the uncertainty in climate forcing by all greenhouse gases released over the past century ( Houghton et al. 1996 ). To reduce this uncertainty, improved measurements of aerosol optical properties are needed for aerosol and climate field studies. Scattering by intervening aerosols provides much of the signal received by earth-viewing satellites ( Gordon

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Rudra Aryal, Paul Terman, and Kenneth J. Voss

1. Introduction Aerosols play an important but poorly constrained role in the radiation budget of the earth–atmosphere system by scattering and absorbing solar and terrestrial radiation (direct effect; Bellouin et al. 2005 ) and by modulating microphysical properties of clouds (indirect effect; Rosenfeld and Lensky 1998 ). The radiative effects of aerosols vary greatly over space and time because they originate from multiple sources with time-varying strengths ( Hinds 2012 ), exhibit

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Brett F. Thornton, Axel Horst, Daniel Carrizo, Henry Holmstrand, Per Andersson, Patrick M. Crill, and Örjan Gustafsson

half of the twenty-first century, overshadowing the waning amounts of anthropogenic chlorofluorocarbons and halons ( Law et al. 2007 ). It has been speculated that changes in atmospheric circulation may transport more short-lived source gases of Cl ( Law et al. 2007 ) and Br ( Dessens et al. 2009 )—such as the methyl halides—to the upper troposphere–lowermost stratosphere (UTLS). This may impact the halogen burden in the UTLS, where ozone changes may have large radiative forcing effects. Both

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Ramon F. Hanssen, Arnout J. Feijt, and Roland Klees

surfaces it is not possible to obtain coherent phase observations. Over many agricultural areas, as in the test site in this study, phase noise increases with increasing time intervals or after anthropogenic activities (see, e.g., Usai and Klees 1999 ). During the ERS-1 and ERS-2 “tandem mission,” which lasted from August 1995 to April 1996, SAR images were acquired with a repeat period of 24 h. This short time interval ensures a sufficiently high correlation between consecutive acquisitions over

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Luis A. Gil-Alana

support the view that the northern, southern, and global temperatures are I ( d ), with d constrained between 0 and 1. Moreover, the existence of a structural break at an unknown point in time is also taken into account, examining the implications that this has on the orders of integration and the coefficients associated with the time trends. Table 4 summarizes the results in terms of the warming effects, depending on the assumption made on the disturbance term. As expected, the results

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D. J. Delene and T. Deshler

-0889.47.issue3.1.x Chuang, C. C., J. E. Penner, K. E. Taylor, A. S. Grossman, and J. J. Walton, 1997: An assessment of the radiative effects of anthropogenic sulfate. J. Geophys. Res., 102, 3761–3778. 10.1029/96JD03087 Delene, D. J., T. Deshler, P. Wechsler, and G. Vali, 1998: A balloon-borne cloud condensation nuclei counter. J. Geophys. Res., 103, 8927–8934. 10.1029/98JD00053 de Oliveira, J. C. P., and G. Vali, 1995: Calibration of a photoelectric cloud condensation nucleus counter. Atmos

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Vladimir N. Kapustin, Antony D. Clarke, Steven G. Howell, Cameron S. McNaughton, Vera L. Brekhovskikh, and Jingchuan Zhou

cloud condensation nuclei (CCN) in a dynamic system of aerosol–cloud feedbacks that affect the optical and microphysical characteristics of clouds, cloud lifetimes, and their precipitation patterns. To predict the direct and indirect effects of anthropogenic emissions of aerosol and their precursors on Earth’s radiation balance requires a much better, more complete understanding of these aerosol–cloud interactions ( Solomon et al. 2007 ). There is ample evidence to suggest that SSA plays an

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R. M. Mitchell and B. W. Forgan

., Eds., Cambridge University Press, 289–348 . Rosen, J. , Young S. A. , Laby J. , Kjome N. , and Gras J. L. , 2000 : Springtime aerosol layers in the free troposphere over Australia: Mildura Aerosol Tropospheric Experiment (MATE 98). J. Geophys. Res. , 105 , 17833 – 17842 . 10.1029/2000JD900208 Rotstayn, L. D. , 1999 : Indirect forcing by anthropogenic aerosols: A global climate model calculation of the effective-radius and cloud-lifetime effects. J. Geophys. Res. , 104 , 9369

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