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C. P. Weaver and V. Ramanathan

SEPTEMBER 1996 WEAVER AND RAMANATHAN 2093The Link between Summertime Cloud Radia~five Forcing and Extratropical Cyclones in the North Pacific C. P. WEAVER AND V. RAMANATHANCenter for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, La dolla, California(Manuscript received 27 September 1995, in final form 26 February 1996

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Hui Su and Jonathan H. Jiang

profound importance of clouds on the earth’s radiative energy balance. At the time when no direct observation of cloud vertical profiles on the tropical/global scale was available, a few studies used the ratio of shortwave and longwave cloud forcing (SWCF and LWCF, respectively) at the top of the atmosphere (TOA), N = −SWCF/LWCF, to infer cloud height for the understanding of TOA cloud radiative forcing (CRF) changes. There has been a controversy as to whether the abnormally large N value over the

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John W. Bergman and Harry H. Hendon

diabatic heating and to the individual components: latent heating and radiative heating. The role of clouds is quantified by the circulation driven by “cloud radiative forcing” (CRF), which is calculated by subtracting clear-sky radiative heating rates from the net radiative heating rates. We further diagnose the relative contributions by deep convective clouds, for example, in the intertropical convergence zone (ITCZ), and by shallow cloud fields at subtropical locations. This study is motivated by

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Eric M. Wilcox and V. Ramanathan

sizes, from a few tens of square kilometers to millions of square kilometers. Thus we can expect that the thermodynamic forcing of the column by clouds exists on a corresponding spectrum of sizes. Clouds of different sizes, however, express significant structural differences. Studies of satellite images ( Roca and Ramanathan 2000 ) and ground-based radar echoes ( Houze and Betts 1981 ) suggest that small clouds are dominated by isolated convective elements while larger clouds express an organized

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J. T. Kiehl

APRIL 1994 K I E H L 559 On the Observed Near Cancellation between Longwave and Shortwave Cloud Forcing in Tropical Regions J. T. KIEHL National Center for Atmospheric' Research,* Boulder, Colorado (Manuscript received 21 December 1992, in final form 27 August 1993) ABSTRACT Observations based on Earth Radiation Budget Experiment (ERBE) satellite data

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Wan-Ho Lee, Sam F. Iacobellis, and Richard C. J. Somerville

1. Introduction The net effect of clouds on the radiation balance of the earth, referred to as the cloud radiative forcing, is negative ( Ramanathan et al. 1989 ) and has an average magnitude of about 10–20 W m −2 . It consists of a shortwave cooling (the albedo effect) of about 40–50 W m −2 and a longwave warming (the greenhouse effect) of about 30 W m −2 . The size of the observed average net cloud forcing is several times the expected value of the direct radiative forcing from a doubling of

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Yonghua Chen, Filipe Aires, Jennifer A. Francis, and James R. Miller

decreased during winter and increased during spring and autumn. Our understanding of cloud–radiation interactions and feedbacks in the Arctic is, however, still limited by data sparsity and/or by poor spatial and temporal sampling. Recently available Arctic data from the Surface Heat Budget of the Arctic (SHEBA) ocean project offer new opportunities to evaluate relationships between cloud properties and radiative forcing (e.g., Shupe and Intrieri 2004 ). Even though the record length and spatial

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J. Davoudi, N. A. McFarlane, and T. Birner

large number of clouds. In practice, the number of clouds is finite and convective quantities do fluctuate around their ensemble means. Consequently, a wide range of subgrid-scale states can be consistent with the resolved scale flow and the traditional deterministic schemes should be viewed as a mean field treatment. It is therefore an important issue to characterize the convective variability in terms of the same large-scale forcing that determines the mean values. The convective fluctuations are

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V. Sathiyamoorthy, P. K. Pal, and P. C. Joshi

1. Introduction Clouds affect the radiative energy balance of the earth. They cool the earth–atmosphere system by reflecting a fraction of the incoming solar radiation and warm the system by trapping a fraction of the outgoing longwave terrestrial radiation. It is well established that the top-of-the-atmosphere net cloud radiative forcing (NCRF) in the tropical deep convective regions is nearly zero ( Kiehl and Ramanathan 1990 ). In the Tropics, the top-of-the-atmosphere shortwave cloud

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M. Rajeevan and J. Srinivasan

1. Introduction The concept of cloud radiative forcing has been used extensively to study the impact of clouds on climate. Cloud radiative forcing at the top of the atmosphere is defined as the difference between the radiative fluxes with and without clouds. The observations from the Earth Radiation Budget Experiment (ERBE) provided the first accurate estimate of the modulation of longwave and shortwave radiative fluxes at the top of the atmosphere by clouds ( Ramanathan et al. 1989 ). Using

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