Application of CALMET to the Raleigh-Durham area: A case for denser surface observation to improve model simulations

The developing North Carolina Environmental and Climate Observing Network (NC ECO Net) provides high resolution surface observations that are extremely useful for a wide range of applications. CALMET, a micrometeorological model for the non-steady state, non-homogeneous dispersion model CALPUFF, requires quality surface and upper-air observations for accurate dispersion analysis. In most regions, relatively sparse National Weather Service ASOS surface observations are the only available data. Also, 12-hourly rawinsonde soundings used by the model do not completely provide realistic upper-air information. This study examines the effectiveness of additional surface observations and the inclusion of 3-hourly ETA model soundings. Fine scale applications of CALMET/CALPUFF are shown to require a higher resolution of surface observations than what is provided by the ASOS network. CALMET's description of the planetary boundary layer including mixing height, friction velocity, monin-obukhov length, and convective velocity scale are largely influenced by the surface wind observations. The ETA model soundings provide a better representation of the above surface conditions, leading to enhanced model performance. The incorporation of the NC ECO Net surface observations significantly improves the performance of CALMET