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Joyce E. Penner and Frederick M. Luther

areplotted in constant pressure coordinates. Becausethe calculated local ozone changes are largest on apercentage basis at high altitude (for each of theperturbations considered), monitoring high-altitudeozone changes may provide an early warning signalfor anthropogenically caused ozone changes and amethod for validating models (NASA, 1049). It isimportant, therefore, to include the effects oftemperature feedback and changes in the airdensity when computing local changes in ozone forcomparison with

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V. Aquila, L. D. Oman, R. Stolarski, A. R. Douglass, and P. A. Newman

detected at southern mid- and high latitudes during the year following the eruption ( Zerefos et al. 1994 ; Randel et al. 1995 ; Randel and Wu 1996 ). Figure 1 shows the anomaly of the total ozone column due to the eruption of Mt. Pinatubo as derived from Total Ozone Mapping Spectrometer (TOMS) observations. Fig . 1. Zonal mean of the ozone column anomaly (%) from TOMS observations. The baseline is the 1979–90 column ozone mean from TOMS. Effects due to the seasonal cycle, QBO, ENSO, solar cycle

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James G. Hudson and Seong Soo Yum

established.” This discussion should at least acquaint more readers with ETEM. Much of our motivation was directed at determining the sensitivity of precipitation to differences in cloud condensation nuclei (CCN) concentrations or spectra. Even if this influence turns out to be less than the influence of ETEM (e.g., Telford 1995 ) or other influences, it may still have important climate change implications (e.g., Wigley 1991 ). For, unlike ETEM, CCN have an anthropogenic component that has yet to be

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Jerome Pressman and Peter Warneck

1970 JEROME PRESSMAN AND PETER WARNECK !55The Stratosphere as a Chemical Sink for Carbon Monoxide JERO~I-E PRESSMAN AND PETER WARNECKGCA Corporation, Bedford, Mass.(Manuscript received 27 June 1969, in revised form 5 September 1969)ABSTRACT Past and recent data on atmospheric CO levels indicate no significant increase of average concentrations-despite the increasing anthropogenic emission rate

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Qingyuan Han, William B. Rossow, Jian Zeng, and Ronald Welch

, 2001 : A physically-based estimate of radiative forcing by anthropogenic sulfate aerosol. J. Geophys. Res , 106 , 5279 – 5294 . Greenwald , T. J. , G. L. Stephens , S. A. Christopher , and T. H. Vonder Haar , 1995 : Observations of the global characteristics and regional radiative effects of marine cloud liquid water. J. Climate , 8 , 2928 – 2946 . Greenwald , T. J. , S. A. Christopher , and J. Chou , 1997 : SSM/I and GOES-8 imager comparisons of cloud liquid water

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Zachary J. Lebo

1. Introduction The sensitivity of deep convective clouds to anthropogenic aerosol perturbations has received considerable attention over the last decade (e.g., Khain et al. 2004 ; Wang 2005 ; Grabowski 2006 ; Teller and Levin 2006 ; Van den Heever et al. 2006 ; Tao et al. 2007 ; Lee et al. 2008a ; Rosenfeld et al. 2008 ; Fan et al. 2009 ; Khain and Lynn 2009 ; Koren et al. 2010b ; Noppel et al. 2010 ; Ekman et al. 2011 ; Seifert et al. 2012 ; Morrison 2012 ; Storer and van den

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Akiko Higurashi and Teruyuki Nakajima

, that total sulfate aerosol forcing is comparable in magnitude to the current anthropogenic greenhouse gas forcing but in opposite sign. There is, however, a large uncertainty in the evaluation of both direct and indirect effects of the sulfate aerosols. The forcing mechanism with aerosols is highly complex and needs more study before drawing a clear conclusion. For example, aerosols originated from dimethyl sulfate (DMS) may change cloud microphysics significantly. Such indirect effects will be

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Jiwen Fan and Alexander Khain

conditions and large-scale adjustments over temporal and spatial scales beyond storms ( Stevens and Feingold 2009 ). However, under favorable conditions, such as warm and humid regions over tropics and subtropics, it is also possible that the long-term production of anthropogenic aerosols could have produced large effects on precipitation and circulation. Besides, this effect increases anvil cover and thickness, through which the radiative balance and circulation can be affected. A final note is that SBM

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David Marsden and Richard E. Lingenfelter

variation over the 11-yr solar cycle is very small. Over the 1979–90 solar cycle, for example, the variation in the irradiance was only ∼0.1% ( Fröhlich 2000 ), or ∼0.3 W m −2 , globally averaged at the top of the atmosphere. This is insufficient to power the sea surface temperature changes associated with the solar cycle by a factor of 3–5 ( Lean 1997 ), and is significantly smaller than the globally averaged forcings due to clouds (∼28 W m −2 ; e.g., Hartmann 1993 ), anthropogenic greenhouse gases

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O. Torres, P. K. Bhartia, J. R. Herman, A. Sinyuk, Paul Ginoux, and Brent Holben

's activities, the availability of long-term aerosol data sets is of critical importance to separate the aerosol effects of anthropogenic origin, from those generated by natural processes. Aerosol effects are also significant in non-climate-related processes, such as those related to the analysis of local, regional, and global air pollution. Large-scale biomass burning and boreal forest fire events often cast huge smoke plumes thousands of kilometers away from their sources, causing serious air quality and

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