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IMPLEMENTATION AND EXPERIMENTATION ON AN ADVANCED LAND-SURFACE/PBL MODEL IN THE PENN STATE/NCAR MESOSCALE MODEL (MM4)
Citation:
Xiu, A. AND J. Pleim. IMPLEMENTATION AND EXPERIMENTATION ON AN ADVANCED LAND-SURFACE/PBL MODEL IN THE PENN STATE/NCAR MESOSCALE MODEL (MM4). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-94/061 (NTIS PB94160421).
Description:
A more advanced surface/PBL model is implemented in the Penn State/NCAR Mesoscale Model Version 4 (MM4) which is utilized to provide meteorological data to the Regional Acid Deposition Model (RADM). he diurnal evolution of the Planetary Boundary Layer (PBL) and its dynamic characteristics are crucial to air quality modeling. he PBL is strongly dependent on surface fluxes of heat, moisture and momentum. hese fluxes are largely controlled by soil moisture and vegetative evapotranspiration. reviously, the MM4 was unable to respond to dynamic soil moisture conditions, leading to unrealistic partitioning of the surface energy budget between sensible and latent heat fluxes. he new model includes explicit soil moisture and evapotranspiration, as well as improved radiation and cloud cover algorithms, flux-profile relationships, and PBL mixing. he soil-vegetation-atmosphere transfer scheme is similar to the scheme developed for the French Weather Service mesoscale meteorological model. he PBL mixing scheme, a hybrid of eddy diffusion and non-local closure, is the same as is currently used in the RADM. he model has been previously tested in 1-D form against several field experiments and has demonstrated good agreement with measurements, The land-surface/PBL model was recently implemented into the fully three-dimensional MM4 system. eries of tests were performed to investigate the impact and veracity of the modal modifications. ecause of our emphasis on air quality applications, the evaluation focused rimarily on the height of the PBL and on surface fluxes and PBL temperatures and moisture. odel results were compared with results from the current MM4 and with observations. n addition, 3-D simulations of intensive field studies, such as FIFE, were performed using both versions of the MM4.
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IMPLEMENTATION AND EXPERIMENTATION ON AN ADVANCED LAND-SURFACE/PBL MODEL IN THE PENN STATE/NCAR MESOSCALE MODEL (MM4)