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K. S. Hintz, H. Vedel, E. Kaas, and N. W. Nielsen

identification number. Additional metadata were collected from other sources to assess the impact of using the roughness length derived from the HWMs and to examine the effects of the stability correction: We looked at the characteristics of the surface in the form of roughness lengths from two different sources, used for comparison with the roughness length determined via the HWMs. In addition, the surface was characterized subjectively by the authors. We looked at the lower tropospheric atmospheric

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Michael E. Feinholz, Stephanie J. Flora, Mark A. Yarbrough, Keith R. Lykke, Steven W. Brown, B. Carol Johnson, and Dennis K. Clark

earth’s carbon balance and the relationship between the ocean’s productivity and the earth’s climate. Multisensor, multiyear measurements are required to develop an understanding of the state of the world’s oceans and their response to environmental changes. Of particular interest are measurements of oceanic ecosystem changes attributable to anthropogenic origins. Meaningful synthesis of measurements from multiple sensors over decadal time scales into a coherent picture of the evolution of the earth

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Pierre Cauchy, Karen J. Heywood, Nathan D. Merchant, Bastien Y. Queste, and Pierre Testor

underwater sound sources (e.g., spectrum shape, time variability) allow wind-generated noise to be isolated and quantified ( Fig. 1 ). Fig . 1. Spectra of the typical contributions to underwater ambient noise in the open ocean, from anthropogenic (dashed), biotic (dotted), and abiotic (continuous) sources [adapted from Wenz (1962 )]. In the absence of heavy rain events or nearby biotic activity, wind-generated noise is predominant in the 500 Hz–20 kHz frequency range. Underwater noise generated by

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Patrick Y. Chuang, Athanasios Nenes, James N. Smith, Richard C. Flagan, and John H. Seinfeld

1. Introduction Cloud condensation nuclei (CCN), those particles that nucleate cloud droplet formation, influence the droplet number and size distribution in a cloud, which in turn determine the cloud albedo, lifetime, and precipitation rate, with important climate effects ( IPCC 1996 ; Twomey 1977 ). Knowledge of the nature of CCN is essential to understanding possible anthropogenically induced climate change. Ideally, a measurement of cloud condensation nuclei would reveal the distribution

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Kevin S. Repasky, John A. Reagan, Amin R. Nehrir, David S. Hoffman, Michael J. Thomas, John L. Carlsten, Joseph A. Shaw, and Glenn E. Shaw

aerosol optical depth and lidar ratio retrieved using the solar radiometer. Furthermore, the scattering component of the aerosol extinction calculated using the single-scatter albedo retrieved with the solar radiometer and the total aerosol extinction retrieved using the two-color lidar is compared with the scattering component of the aerosol extinction measured using the ground-based nephelometer. The ability to measure aerosol optical properties is important for understanding the effects of aerosols

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Steven D. Miller, Cynthia L. Combs, Stanley Q. Kidder, and Thomas F. Lee

unique information for numerous qualitative and quantitative nighttime applications. Studies on population density ( Sutton et al. 2001 ), economic activity (e.g., Ebener et al. 2005 ), and atmospheric emissions (e.g., Toenges-Schuller et al. 2006 ) use correlations between these parameters and the distribution/intensity of anthropogenic light emissions. Environmental studies related to aerosol properties ( Zhang et al. 2008 ), cloud and snow/ice cover ( Foster and Hall 1991 ; Miller et al. 2005b

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Fabien Gibert, Pierre H. Flamant, Juan Cuesta, and Didier Bruneau

observe 1) large regional- and synoptic-scale sources, sinks, and gradients in the ABL ( Wang et al. 2007 ); 2) changes in tropospheric CO 2 associated with the passage of strong frontal boundaries (magnitude of a few to 40 ppm; Hurwitz et al. 2004 ); and 3) variations of the mean CO 2 mixing ratio in the ABL due to anthropogenic emissions ( Idso et al. 2002 ; Braud et al. 2004 ). However, this will only marginally constrain the ABL-mean diurnal cycle in CO 2 associated with the biological cycle

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Grant Matthews

climate on the earth. The measurement accuracy and calibration stability required to detect model-predicted effects of cloud–climate feedbacks on the ERB has recently been estimated by Ohring et al. (2005) . The standards called for are an absolute accuracy of 1 W m −2 , a calibration stability of ±0.3% decade −1 for SW flux, and ±0.5% decade −1 for LW flux. The Clouds and the Earth’s Radiant Energy System (CERES; Wielicki et al. 1996 ) is currently the only satellite program monitoring global ERB

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Francesca Barnaba and Gian Paolo Gobbi

1. Introduction Atmospheric aerosols are both efficient scatterers of solar radiation and efficient cloud condensation nuclei. Overall, the combination of these effects translates into a negative radiative forcing, that is, a cooling that contrasts greenhouse gas warming (e.g., Penner et al. 2001 ). Despite such a climatic impact, these particles still represent a major unknown in the atmospheric system. This is mainly due to their high spatial and temporal variability and to their complex

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Wolfgang Junkermann

either enhanced or decreased in different altitudes of the planetary boundary layer ( Jacobson 1998 ), while at ground level reductions of more than 50% can be expected under high-pollution episodes. Model calculations were presented by Madronich (1987) , van Weele and Dynkerke (1993), de Arrellano et al. (1994) , Ruggaber et al. (1994) , Wendisch et al. (1996) , Wendisch and Keil (1999) , Dickerson et al. (1997) , Jacobson (1998) , and Früh et al. (2000) , either focusing on aerosol effects

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