Spatially-varying surface fluxes at the Southern Great Plains cart site and their effects on boundary-layer properties
- Pacific Northwest Lab., Richland, WA (United States)
In this paper, data from the US DOE Cloud and Radiation Testbed (CART) site is combined with results from a mesoscale model to examine the effects of spatially-varying surface fluxes on some features of the planetary boundary layer (PBL). Precipitation data from several sources was used to generate objectively-interpolated precipitation fields over the CART domain, and daily precipitation totals were assigned to each grid point in the domain. Normalized difference vegetation index values were averaged and a value assigned to each grid point. Surface sensible and latent heat flux values from the CART instruments were fitted to a bilinear function and flux values were calculated for each grid element. The mesoscale model used for the analysis was the Regional Atmospheric Modeling System (RAMS). For comparison, a case was run in which soil moisture and vegetation cover in the model domain was made uniform and adjusted to produce flux values equal to the spatial average of the latent heat fluxes calculated with RAMS. Results indicate that there a number of PBL properties that may be sensitive to the proper specification of surface fluxes. In addition to mesoscale fluxes, these include features such as the depth of the mixed layer and the likelihood of cloud formation. Comparison of the results for the latter two quantities was performed for simulations with and without spatially resolved fluxes. Results for the test case showed that even if the spatial variation of surface fluxes is not resolved over areas smaller than 10{sup 5} km{sup 2}, there may be relatively little impact on a general circulation model`s ability to describe cloud formation. In general, results indicate that some aspects of subgrid-scale variations of surface fluxes may not be as important to the performance of general circulation models as previously implied. 14 refs., 5 figs.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 535155
- Report Number(s):
- CONF-960146-; TRN: 97:005075-0016
- Resource Relation:
- Conference: 7. American Meteorological Society (AMS) symposium on global change studies, Atlanta, GA (United States), 28 Jan - 2 Feb 1996; Other Information: PBD: 1996; Related Information: Is Part Of Seventh symposium on global change studies; PB: 205 p.
- Country of Publication:
- United States
- Language:
- English
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