A Comparison of Mesh Refinement in the Global MPAS-A and WRF Models Using an Idealized Normal-Mode Baroclinic Wave Simulation

Sang-Hun Park
National Center for Atmospheric Research
Boulder, Colorado, USA

Idealized normal-mode baroclinic wave simulations are conducted to demonstrate the numerical impact of the continuous mesh refinement used in the non-hydrostatic Model for Prediction Across Scales - Atmosphere (MPAS-A) compared with the stepwise changes in resolution using nested grids in the Weather Research and Forecasting (WRF) model.

Although one-way and two-way grid nesting is widely used in high-resolution mesoscale models, it is well-known that the lateral boundary conditions in these models can be a significant issue such as wave reflection. In this study, we compare the one- and two-way nesting approaches, investigating the potential problems of these grids using a key mid-latitude feature the baroclinic wave in our simulations. Using MPAS-A, Voronoi meshes with different transitional zones between high- and low-resolution regions are tested and compared with the results from the WRF simulations. In the MPAS-A simulations, there is no artificial widening of frontal systems or reflection of gravity waves; comparison with WRF shows that continuous mesh refinement can eliminate distortions that tend to occur along the boundaries of higher-resolution nested meshes.

In this presentation, key differences that result from lateral boundaries will be described, and the possibility of errors at lateral boundaries being reflected into the domain will be investigated. 

Thursday, 18 July 2013, 3:30 PM
Refreshments 3:15 PM
NCAR-Foothills Laboratory
3450 Mitchell Lane
Bldg 2 Small Seminar Room 1001

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Sang-Hun Park

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1001

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Thursday, July 18, 2013 - 3:30pm