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Sensitivity of the WRF-NMM Model to Physics Parameterizations at Various Vertical and Horizontal Resolutions. Jian-Wen Bao (ESRL/PSD) S. G. Gopalakrishnan (AOML/HRD) Sara A. Michelson (ESRL/PSD) NOAA/OAR in collaboration with Frank Marks of AMOL/HRD, and Vijay Tallapragada of NCEP/EMC.
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Sensitivity of the WRF-NMM Model to Physics Parameterizations at Various Vertical and Horizontal Resolutions Jian-Wen Bao (ESRL/PSD) S. G. Gopalakrishnan (AOML/HRD) Sara A. Michelson (ESRL/PSD) NOAA/OAR in collaboration with Frank Marks of AMOL/HRD, and Vijay Tallapragada of NCEP/EMC Presented at The 64th Interdepartmental Hurricane Conference Savannah, GA, 1-4 March 2010
Motivation and methodology Model initialization and physics options tested so far Highlighted results Summary Outline
To explore the flexibility of running HWRF with various • physics options in the WRF-NMM modeling framework. • To benchmark the response of the WRF-NMM dynamic • core to various permutations of physics options. Motivation Methodology • Idealized case setup to complement real-event investigation • Evaluation with observation composites and theoretical understanding
Model Initialization • f plane located at 12.5ºN • A prescribed axisymmetric vortex: — maximum sfc tangential wind: 15 m/s — radius of sfc maximum wind: 90 km • Quiescent environment thermally corresponding to the Jordan sounding with a constant sea surface temperature of 29ºC • Initial mass and wind fields derived by solving the nonlinear balance equation for the prescribed vortex (Wang 1995, MWR)
Physics Options Tested So Far SL/ABL Physics Options MYJ (NMM Default) GFS (HWRF Default) Microphysics Options Option # = 4, WSM 5-class scheme = 5, Ferrier (new Eta) = 6, WSM 6-class graupel scheme = 8, Thompson scheme Subgrid Convection Options SAS (HWRF default) BMJ (Betts-Miller, NMM default) Radiation Options Option # = 1, Dudhia SW and RRTM LW Option # = 99, GFDL SW and LW (NMM default)
Physics Permutations Model grid spacing: dx = 0.06, 0.02 (~9 km, ~ 3 km) dy = 0.06, 0.02 (~9 km, ~ 3 km) kx = 43 (NMM sigma-p levels)
Sensitivity to SL/ABL and Radiation Max Surface Wind Speed Min Sea-Level Pressure 36-48 h
Sensitivity to microphysics and Sub-Grid Convection Max Surface Wind Speed Min Sea-Level Pressure 36-48 h
36-48 h average Color shades: vertical motion Contours: radial winds Arrows: circ. vectors MYJ PBL Exp. 1 Exp. 3 Exp. 2 Exp. 5 Exp. 6 Exp. 4 Exp. 9 MYJ PBL Exp. 8 Exp. 7
Color Shades: Tan. Acc. Averaged over hours 36-48 Contours: Tangential winds Arrows: Circulation vectors Exp. 2 GFS PBL Exp. 1 MYJ PBL
Summary (1) It is useful to set up idealized benchmark cases for the evaluation and understanding of ongoing improvements of WRF-NMM/HWRF. (2) The intensification, as realized by the WRF-NMM model, is sensitive to both the SL/ABL physics options, the cloud physics options and the radiation options. (3) Different permutations of the SL/ABL and the cloud physics lead to various dynamical properties of the vortex in terms of du/dt and dv/dt . (4) Future work will be focused on using observational analysis and theoretical understanding to help determine an “improved”, operational physics configuration.