Joint Seminar: Land surface–precipitation interactions in the North American Monsoon: Observational and coupled surface-atmosphere modeling studies

Regions of western Mexico and the southwest United States receive 40-80% of their annual rainfall from precipitation associated with the North American Monsoon (NAM). Convective processes that are responsible for much of this precipitation have yet to be adequately simulated by regional climate models, suggesting that physical mechanisms controlling convection have are not properly represented in these models. To examine sources of uncertainties in prediction of the NAM, this study considers the sensitivity of simulated precipitation patterns during the monsoon observed by the North American Monsoon Experiment-2004 to different land surface treatments through the use of a high resolution modeling system that dynamically couples land surface and mesoscale meteorology models.

 

Synoptic-scale sources of moisture in the NAM have been identified as the Gulf of Mexico, the Gulf of California, and the Pacific Ocean, but ongoing work seeks to establish the contribution of local land surface features to low-level moisture and subsequent influences on precipitation processes. Factors such as local gradients in soil moisture, soil temperature, and evapotranspiration have been found to play a critical role in convective initiation over the Southern Plains of the United States, and play a critical role in simulating the diurnal cycle of convection in the NAM as well. The Land Information System (LIS), developed by NASA, is run with the Noah land surface model (LSM) “offline” to create a high-resolution land surface dataset to initialize a run of the Weather Research and Forecasting model (WRF) for the 2004 monsoon season at spatial resolutions up to 1 km. Output from WRF, run with the Noah LSM and observationally enhanced datasets from the North American Regional Reanalysis (NARR), will be compared against output from LIS-initialized WRF simulations. By conducting sensitivity studies using WRF and LIS-WRF, we demonstrate known spatial and temporal varying precipitation patterns to processes involving interaction of the land surface and atmosphere.

Date

13.10.2010

Time

13:30 h

Place

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

Speaker

Steve Nesbitt, University of Illinois

Organizers


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