A model comparison of basic and surface energy variables in the development of the PBL in a southeast Texas coastal region
Wilmot, Cari-Sue M. 1983-
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Air quality forecasting requires atmospheric weather models to generate reliable and accurate meteorological conditions. Some variables are well-simulated, but others, like the planetary boundary layer (PBL) height, are not as accurately reproduced. This study compares rarely observed energy balance and turbulence variables to modeled results, and seeks to determine if and to what extent these variables contribute to the development of the PBL. Similarly configured MM5 and WRF model outputs were compared to observations of temperature, wind fields, radiation, heat fluxes, and PBL heights during an intensive field campaign on the Gulf Coast in the summer of 2006. The r2 and bias values were calculated as a measure of model performance. The results showed that in general, WRF performed comparably or better than MM5 for all variables except wind speed and directions, sensible heat flux, ground flux, and PBL height. Nighttime simulations for both models are not well-parameterized except for water vapor mixing ratio. PBL height timing was good for both models, but the morning development was not well-simulated. A frontal passage occurred during the study period that led to two mostly cloud-free days; on these days the relationship between incoming solar radiation and the energy variables suggests that there may be an energy sink in the models that could lead to underestimations of PBL height. The dry bias or disparate land-surface initialization datasets might contribute to deviations of the models from the observations and may explain the models' PBL height performance. Further examination of the energy budget and turbulent dataset under extended cloud-free days could provide a better understanding of these variables to PBL height development and lead to better air quality predictions.