A Comparison Framework to Evaluate TWP-ICE Cloud-resolving Simulations with Observations

Adam Varble University of Utah
Edward Zipser University of Utah
Ann Fridlind NASA - Goddard Institute for Space Studies
Ping Zhu Florida International University
Jean-Pierre Chaboureau University of Toulouse, France/CNRS
Jean-Pierre Pinty University of Toulouse, France/CNRS
Jiwen Fan Pacific Northwest National Laboratory
Jimy Dudhia NCAR
Adrian Hill UK Meteorological Office

Category: Cloud Properties

Working Group: Cloud Life Cycle

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The model-versus-observations comparison framework consists of three sections, the first of which is addressed in this study. In section I, the model precipitation systems are separated into convective and stratiform regions. Radar reflectivity, vertical velocity, and microphysics are compared in the convective regions, while radar reflectivity and microphysics are compared in stratiform regions. Cold-pool properties spanning both regions are also examined. Yet to be started are sections II and III. Section II consists of further examining results of section I through model-versus-model comparisons and sensitivity analyses. The ultimate goal is to improve model parameterizations in section III.

A range of different model simulations have been performed for the monsoon period of the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) as part of the Cloud Resolving Model (CRM) Intercomparison Study (Fridlind et al. 2009) and Limited Area Model (LAM) Intercomparison Study. A model-versus-observations comparison framework, shown in the figure, has been developed to establish inconsistencies between simulated and observed oceanic tropical convective properties. This framework is unique in that convective scale and mesoscale properties are compared as opposed to domain-averaged quantities. C-band polarimetric radar (CPOL) reflectivity is compared to simulated radar reflectivity in six CRM simulations and two LAM simulations for convective and stratiform regions separately. Three CRM simulations employ one-moment microphysics schemes: DHARMA, Meso-NH, and UKMO. There are also a Meso-NH simulation and SAM simulation that use a two-moment scheme and one DHARMA simulation that uses a bin scheme. For the LAM simulations, one run employs the new Thompson microphysics scheme in WRF, and the other uses the WSM6 scheme. Differences between observed reflectivity and model-simulated reflectivity are then further investigated in two ways. First, updraft and downdraft vertical velocity statistics are compared with dual Doppler radar results. Second, microphysics characteristics are compared with the CPOL microphysics species algorithm and drop-size distribution (DSD) retrievals. Cold pool and gust front properties are also compared with surface station observational data. Section I of the framework can be made more robust as more observations and model analyses are added, which is one objective going forward. A second aim is to begin section II of the analysis, which involves model-versus-model comparisons of several properties to aid understanding of the results of section I. Ultimately, the third and final goal is to utilize results from sections I and II to improve model parameterizations on all scales, especially within but not limited to bulk microphysics schemes, for use in modeling tropical oceanic convection.

This poster will be displayed at ASR Science Team Meeting.

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