Combining a Cloud-Resolving Model with Satellite for Cloud Process Model Simulation Validation

Advances in computer power have made it possible to increase the spatial resolution of regional numerical models to a scale encompassing larger convective elements of less than 5km in size. One goal of high resolution is to begin to resolve convective processes, and therefore it is necessary to evaluate the realism of convective clouds resolved explicitly at this resolution. This paper presents a method that is based on satellite comparisons to examine the simulation of continental tropical convection over Africa, in a high-resolution integration of the Met Office Unified Model (UK UM), developed under the Cascade project. The spatial resolution of these simulations is 1.5km, the temporal resolution is 15min, and the convection is resolved explicitly. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) radiometer measurements were simulated by the Radiative Transfer for the Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (RTTOV) model, and then a comparison between the simulations and real SEVIRI measurements was performed. The analysis using the presented method shows that the UK UM can represent tropical convection dynamics realistically. However, an error has been found in the high-level humidity distribution, which is characterized by strong humidity gradients. A key point of this paper is to present a method for establishing the credibility of a convection-permitting model by direct comparison with satellite data.

[1]  Steven A. Ackerman,et al.  The 27–28 October 1986 FIRE IFO Cirrus Case Study: Spectral Properties of Cirrus Clouds in the 8–12 μm Window , 1990 .

[2]  A. Staniforth,et al.  A new dynamical core for the Met Office's global and regional modelling of the atmosphere , 2005 .

[3]  C. Borel,et al.  Mixed phase cloud water/ice structure from high spatial resolution satellite data , 2004 .

[4]  Nigel Roberts,et al.  Characteristics of high-resolution versions of the Met Office unified model for forecasting convection over the United Kingdom , 2008 .

[5]  William B. Rossow,et al.  Structural Characteristics and Radiative Properties of Tropical Cloud Clusters , 1993 .

[6]  H. Laurent,et al.  The Convective System Area Expansion over Amazonia and Its Relationships with Convective System Life Duration and High-Level Wind Divergence , 2004 .

[7]  Hiroaki Miura,et al.  Diurnal Cycle of Precipitation in the Tropics Simulated in a Global Cloud-Resolving Model , 2009 .

[8]  M. Ringer,et al.  Simulation of satellite channel radiances in the Met Office Unified Model , 2003 .

[9]  Lance M. Leslie,et al.  The prediction of two cases of severe convection: implications for forecast guidance , 2002 .

[10]  Michael D. King,et al.  Comparison of near‐infrared and thermal infrared cloud phase detections , 2006 .

[11]  R. Hogan,et al.  Evaluation of the model representation of the evolution of convective systems using satellite observations of outgoing longwave radiation , 2010 .

[12]  Damian R. Wilson,et al.  A microphysically based precipitation scheme for the UK meteorological office unified model , 1999 .

[13]  F. Chevallier,et al.  Model Clouds as Seen from Space: Comparison with Geostationary Imagery in the 11-μm Window Channel , 2002 .

[14]  J. Schmetz,et al.  AN INTRODUCTION TO METEOSAT SECOND GENERATION (MSG) , 2002 .

[15]  Luiz A. T. Machado,et al.  Forecast and Tracking the Evolution of Cloud Clusters (ForTraCC) Using Satellite Infrared Imagery: Methodology and Validation , 2008 .

[16]  Barnaby S. Love,et al.  The diurnal cycle of precipitation over the Maritime Continent in a high‐resolution atmospheric model , 2011 .

[17]  Chris Snyder,et al.  The Fronts and Atlantic Storm-Track Experiment (FASTEX) : Scientific objectives and experimental design , 1997 .

[18]  M. Matricardi,et al.  An improved fast radiative transfer model for assimilation of satellite radiance observations , 1999 .

[19]  Charles A. Doswell,et al.  Observations and Fine-Grid Simulations of a Convective Outbreak in Northeastern Spain: Importance of Diurnal Forcing and Convective Cold Pools , 2001 .

[20]  W. Paul Menzel,et al.  Cloud Properties inferred from 812-µm Data , 1994 .

[21]  N. Lau,et al.  Simulation of the Diurnal Cycle in Tropical Rainfall and Circulation during Boreal Summer with a High-Resolution GCM , 2010 .

[22]  J. Morcrette,et al.  Evaluation of a cloud system life‐cycle simulated by the Meso‐NH model during FASTEX using METEOSAT radiances and TOVS‐3I cloud retrievals , 2000 .

[23]  L. Durieux,et al.  Characteristics of the Amazonian mesoscale convective systems observed from satellite and radar during the WETAMC/LBA experiment , 2002 .

[24]  J. Done,et al.  The next generation of NWP: explicit forecasts of convection using the weather research and forecasting (WRF) model , 2004 .

[25]  A. Slingo,et al.  Simulation of the diurnal cycle in a climate model and its evaluation using data from Meteosat 7 , 2004 .

[26]  G. Martin,et al.  A New Boundary Layer Mixing Scheme. Part I: Scheme Description and Single-Column Model Tests , 2000 .

[27]  Peter Pilewskie,et al.  Discrimination of ice from water in clouds by optical remote sensing , 1987 .