Extended Abstract (1.5M)J9.1
The role of fine-scale landscape and soil-moisture variability in convection initiation
Fei Chen, NCAR, Boulder, CO; and S. B. Trier and K. W. Manning
Understanding the feedback between land-surface variability and precipitation is important because of its potential benefit in improving climate predictability. In summer, mesoscale boundaries play a critical role in the initiation of heavy precipitation. The zones of enhanced convergence along these boundaries have been recognized as areas of deep-convection initiation. The differential heating can be enhanced by heterogeneities in land-surface conditions. The land surface may have differing impacts, depending on atmospheric conditions. Small-scale ground features, such as vegetation, hillslopes, and urban or industrial areas can also have subtle impacts that can determine the exact boundary and intensity of storms.
We will present a recent results focusing on heavy precipitation associated with a dryline in the southcentral US, It is found that fine-scale (L~10 km) boundary-layer circulations that directly trigger deep convection are confined within a mesoscale region containing a deeper and more unstable PBL, and that this region is a result of a surface sensible heat-flux maximum over dry soils. They utilized the soil moisture fields from a high-resolution land data-assimilation system (HRLDAS) and from NCEP EDAS to initialize the MM5 model. Results from these and other recent research studies provide some hope that the careful treatment of land-surface physics and soil moisture in convection-resolving models can lead to increased rainfall predictability.
Joint Session 9, Understanding and predicting the water cycle across scale part II (Joint between the Limited Water Supply Symposium the 16th Conference on Planned and Inadvertent Weather Modification)
Thursday, 13 January 2005, 11:00 AM-12:00 PM
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