Sensitivity of planetary boundary layer to varying volumetric soil moisture

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Monday, 18 January 2010
Astrid Suarez-Gonzalez, Western Kentucky University, Bowling Green, KY; and A. I. Quintanar, R. Mahmood, A. Beltran-Przekurat, and R. A. Pielke Sr.

A comparison between two mesoscale models, Colorado State University Regional Atmospheric Model System (RAMS) version 4.4 coupled with the Land-Ecosystem–Atmosphere Feedback Model (LEAF2) and Penn State/NCAR's Mesoscale Model (MM5) coupled with NOAH Land Surface Model, were conducted in order to assess the sensitivity of forecasted boundary layer variables to anomalous volumetric soil moistures. The study elaborates on the findings of Quintanar et al (2008) using the aforementioned experimental design as a template for the numerical model comparison. The experiment was conducted using the same synoptic events examined by Quintanar et al (2008): June 11, June 17 and June 22, 2006. For each event, six simulations were conducted with RAMSv4.4 and MM5 in which volumetric soil moisture was increase and decreased by 0.05, 0.10, and 0.15 (m3m-3). The simulations were initialized with 1x1 degree FNL-Reanalysis data and a horizontal grid resolution of 12km. Each resulting simulation was individually analyzed. Ensemble means were also computed from wet and dry experiment (increased and decreased soil moisture respectively) and compared to each other and to the computed controls. Overall, MM5 ensemble simulations presented a greater sensitivity and variability when forecasting precipitation and potential temperature, while RAMSv4.4 ensemble comparison presented greater variability resolving surface winds.