Validation and Sensitivities of Frontal Clouds Simulated by the ECMWF Model

Abstract Clouds simulated by the European Centre for Medium-Range Weather Forecasts (ECMWF) model are composited to derive the typical organization of clouds surrounding a midlatitude baroclinic system. Comparison of this composite of about 200 cyclones with that based on satellite data reveals that the ECMWF model quite accurately simulates the general positioning of clouds relative to a low pressure center. However, the optical depths of the model’s high/low clouds are too small/large relative to the satellite observations, and the model lacks the midlevel topped clouds observed to the west of the surface cold front. Sensitivity studies with the ECMWF model reveal that the error in high-cloud optical depths is more sensitive to the assumptions applied to the ice microphysics than to the inclusion of cloud advection or a change of horizontal resolution from 0.5625° to 1.69° lat. This reflects the fact that in the ECMWF model gravitational settling is the most rapid process controlling the abundance of ic...

[1]  Toby N. Carlson,et al.  Airflow Through Midlatitude Cyclones and the Comma Cloud Pattern , 1980 .

[2]  Bruce A. Kunkel,et al.  Parameterization of Droplet Terminal Velocity and Extinction Coefficient in Fog Models , 1984 .

[3]  Jean-Jacques Morcrette,et al.  The Overlapping of Cloud Layers in Shortwave Radiation Parameterizations , 1986 .

[4]  Hilding Sundqvist,et al.  Parameterization of Condensation and Associated Clouds in Models for Weather Prediction and General Circulation Simulation , 1988 .

[5]  J. Curry,et al.  Cloud overlap statistics , 1989 .

[6]  Keith A. Browning,et al.  Organization of Clouds and Precipitation in Extratropical Cyclones , 1990 .

[7]  Andrew J. Heymsfield,et al.  A scheme for parameterizing ice cloud water content in general circulation models , 1990 .

[8]  M. Tiedtke,et al.  Representation of Clouds in Large-Scale Models , 1993 .

[9]  Stephen G. Warren,et al.  Edited synoptic cloud reports from ships and land stations over the globe , 1996 .

[10]  Jun-Hong Wang,et al.  Determination of cloud vertical structure from upper air observations and its effects on atmospheric circulation in a GCM , 1995 .

[11]  N. Lau,et al.  A Satellite View of the Synoptic-Scale Organization of Cloud Properties in Midlatitude and Tropical Circulation Systems , 1995 .

[12]  Anthony D. Del Genio,et al.  A Prognostic Cloud Water Parameterization for Global Climate Models , 1996 .

[13]  Donald P. Wylie,et al.  Comparison of the Climatologies of High-Level Clouds from HIRS and ISCCP , 1996 .

[14]  D. Randall,et al.  Liquid and Ice Cloud Microphysics in the CSU General Circulation Model , 1996 .

[15]  H. Treut,et al.  A methodology study of the validation of clouds in GCMs using ISCCP satellite observations , 1996 .

[16]  N. Lau,et al.  Comparing Satellite and Surface Observations of Cloud Patterns in Synoptic-Scale Circulation Systems , 1997 .

[17]  S. Ballard,et al.  Midlatitude cyclonic cloud systems and their features affecting large scales and climate , 1998 .

[18]  Simulation of fog with the ECMWF prognostic cloud scheme , 1999 .

[19]  Christian Jakob,et al.  Cloud Cover in the ECMWF Reanalysis , 1999 .

[20]  C. J. Hahn,et al.  Extended Edited Synoptic Cloud Reports from Ships and Land Stations Over the Globe, 1952-1996 , 1999 .