The importance of mesoscale circulations generated by subgrid-scale landscape heterogeneities in general circulation models
Journal Article
·
· Journal of Climate
- Rutgers Univ., New Brunswick, NJ (United States)
- Goddard Institute for Space Studies, New York, NY (United States)
A mesoscale atmospheric model was used to evaluate the impact of subgrid-scale landscape discontinuities on the vertical profiles of resolved temperature, moisture, and moist static energy in the planetary boundary layer (PBL) of GCMs. these profiles were produced with a 3D version of the model (using a horizontal grid resolution of 7.5 km and 13 vertical layers in the PBL) by averaging horizontally the various atmospheric variables over a 180 x 180 km{sup 2} domain-about the size of the horizontal domain represented by a single grid element in a GCM. They were compared to corresponding vertical profiles produced with a 1D version of the model, which simulates the PBL, as in a GCM, over a single horizontal grid element. Differences obtained between the horizontally averaged atmospheric variables produced with the 3D simulations and the 1D simulations emphasize the impact of subgrid-scale landscape discontinuities on GCM-resolved variables. Various types of landscape discontinuities, characterized by horizontal contrasts of surface wetness and size of land patches, were simulated under various background-wind conditions. Differences of temperature, specific humidity, and moist static energy as large as 4 K, 6 g kg{sup -1}, and 10 kJ kg{sup -1} were obtained in some cases. These differences were not affected significantly by moderate winds but were sensitive to the spatial distribution of surface wetness. These results emphasize the need to parameterize mesoscale processes induced by landscape discontinuities in GCMs. 38 refs., 11 figs., 3 tabs.
- DOE Contract Number:
- FG02-92ER61453
- OSTI ID:
- 79388
- Journal Information:
- Journal of Climate, Journal Name: Journal of Climate Journal Issue: 2 Vol. 8; ISSN 0894-8755; ISSN JLCLEL
- Country of Publication:
- United States
- Language:
- English
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