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Xiaoqing Wu, Xin-Zhong Liang, and Sunwook Park

independent datasets such as longwave and shortwave radiative flux, cloud radiative forcing, surface sensible and latent heat fluxes, and airborne radar reflectivity. The general agreement between modeled and satellite-retrieved radiative fluxes gives confidence in the use of CRM-generated cloud and radiative properties to evaluate the cloud and radiation parameterization schemes of GCMs ( Wu and Moncrieff 2001 ). The TOGA COARE observations and successful long-term CRM simulations help establish the

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Nathalie Söhne, Jean-Pierre Chaboureau, and Françoise Guichard

eastern boundaries of the domain. In the latter case, this is likely a boundary effect due to the coupling that used temperature, water vapor, and wind fields from ECMWF forecasts only. In the other case, the discrepancy may be partly attributed to the too-smooth orography described over the 32-km grid mesh, which leads to an underestimation of the orographic forcing. Between these two main orographic centers, the southern limit of high clouds is well delineated in the model but the occurrence of high

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Gary R. Austin, Robert M. Rauber, Harry T. Ochs III, and L. J. Miller

ratherthan the eastward directed pressure gradient force induced by island blocking. The thermally forced, offshore flow was shown to interact with the trade winds,forcing convergence, lifting, and cloud bands. Carboneet al. (1995) and Chen and Wang ( 1994, 1995) arguedthat diabatic cooling, associated with evaporation ofrainfall near the surface over the island at night, enhances both the strength of the low-level downslopeflow and the offshore convergence during the night,leading to an intensification

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Gary M. Barnes

's demise adequately, in contrastto the trends of vertical velocity, virtual potential temperature, or moisture at cloud base. A pressure perturbationcaused by updraft-shear interaction is an important mechanism for cloud intensification, but it must act inconcert with another forcing mechanism, typically a gust front, to tap the most unstable air found in the lowersubcloud layer in the High Plains. The observations support the numerical simulations of cumulonimbi in the presence of strong shear

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Keith L. Seitter and H. Stuart Muench

840 MONTHLY WEATHER REVIEW VOLUME 113Observation of a Cold Front With Rope Cloud KE~TH L. SEITTER Dept. of Earth Sciences, University of Lowell, Lowell, M~4 01854 H. STUART MUENCHMeteorology Division, Air Force Geophysics Laboratory, Hanscorn AFB, MA 01731(Manuscript received 8 May 1984, in final form 28 January 1985)ABSTRACT Observations are presented of a cold front which passed over the

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Rong-Shyang Sheu and Judith A. Curry

predicting the presence of clouds and their effects onthe atmosphere in the midlatitudes of the North Atlantic Ocean. The European Centre for Medium RangeWeather Forecasting initialized analyses and the U.S. Air Force Three-Dimensional Nephanalysis are employedto construct a joint time series of gridpoint values of cloudiness and large-scale meteorological fields, includingheat and moisture budgets, for January 1979. Interpretation of cloud in the context of the large-scale flow isgiven for the monthly

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Steven J. Ghan, L. Ruby Leung, and James McCaa

as a useful testbed by comparing a GCM simulation with SCM simulations driven by GCM forcing. The GCM is driven by the ECMWF analysis for the experiment period described in section 2 . The SCM is driven by the GCM horizontal and vertical components of velocity, surface pressure, horizontal advective tendencies of temperature, water vapor + cloud water, and cloud ice, and the GCM nudging term for temperature. All of these fields are archived from the GCM simulation every time step at the grid

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Richard G. Gudgel, Anthony Rosati, and C. T. Gordon

, observed low-level cloud fractions and optical depths over both the global oceans and tropical landmasses are specified in the CGCM. This study employs a practical approach to test the sensitivity of the CGCM to radiative forcing over the MSc region and tropical land regions. The availability of satellite-derived, low-level cloud data from ISCCP data provides a useful tool to investigate this potential sensitivity. Certainly, there is disagreement over the optimal observation method for low

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John R. Mecikalski and Kristopher M. Bedka

clouds, and have been omitted from processing. A comparison of the red pixels in Fig. 8 to future radar imagery, at 2103 and 2118 UTC [ Figs. 9b,c for Amarillo] and at 2109 and 2124 UTC [ Figs. 9e,f for Vance Air Force Base, Oklahoma], demonstrates the algorithm's accuracy; this is also seen when comparing Figs. 3a and 8 . This nowcast captured the future development of convection across the Texas panhandle and into Oklahoma (outlined by ovals). Convective cells in the central Texas panhandle

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Pavlos Kollias, Ieng Jo, and Bruce A. Albrecht

of the cloud. While the thermodynamic stability below the cirrus base is not known, the observations presented here provide strong evidence that mechanical processes above the air–cloud interface could force mammatus elements downward even in the absence of thermodynamic instability. Martner (1995) also observed similar turbulent layer and suggested that the root of the mammatus clouds is deep in the cloud. Layers of high turbulence due to buoyancy and shear instabilities are often encountered

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