Development of a land-surface/PBL parameterization for mesoscale meteorology models in support of air quality models
- MCNC-North Carolina Supercomputing Center, Research Triangle Park, NC (United States)
- National Oceanic and Atmospheric Administration, Research Triangle Park, NC (United States)
Simulation of land-surface and Planetary Boundary Layer (PBL) processes in meteorology models is very crucial for air quality modeling. Dry deposition, emissions and vertical mixing of chemical species in PBL are controlled by surface heat fluxes and models, land-surface and PBL processes need to be realistically parameterized. The available solar radiation reaching the earth surface is partitioned to sensible and latent heat fluxes and this partitioning is highly dependent on vegetation coverage and soil moisture content. In some meteorology models, such as the Penn State/NCAR Mesoscale Model Generation 5 (MM5), there is no explicit soil moisture included and the surface moisture flux is parameterized based on moisture availability which is specified as a function of land-use category and season only. This approach would mislead the model results whenever the soil moisture differs from the prescribed moisture availability because of precipitation of drought. Thus, a more sophisticated land-surface/PBL parameterization scheme is developed and implemented in the MM5 for air quality modeling applications. The land- surface model has five prognostic equations for soil temperature and moisture in two soil layers, and canopy moisture conservation equations in the surface soil layer (1 cm) and treats the deeper layer (1m) as a reservoir of heat and moisture for a force-restore algorithm. The moisture flux has three components including bare soil evaporation, evapotranspiration, and evaporation from wet part of canopy. The Asymmetric Convective Scheme (ACM) is used for PBL mixing. A nudging scheme for assimilating soil moisture in the model is developed to reduce errors introduced by soil moisture initialization and the parameterization itself. Several experiments are performed with the MM5 including this new scheme. The model results are compared against field studies such as FIFE (First ISLSCP Field Experiment) and EPA NDDN (National Dry Deposition Network) measurements.
- OSTI ID:
- 466303
- Report Number(s):
- CONF-9606185-; TRN: 96:005931-0256
- Resource Relation:
- Conference: 5. international conference on atmospheric sciences and applications to air quality, Seattle, WA (United States), 18-20 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of The 5th international atmospheric sciences and applications to air quality conference; PB: 322 p.
- Country of Publication:
- United States
- Language:
- English
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