A comparison of the MM5 and the Regional Atmospheric Modeling System simulations for land–atmosphere interactions under varying soil moisture

Abstract

A comparison between two mesoscale models, Colorado State University Regional Atmospheric Modeling 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, was conducted in order to assess the sensitivity of forecasted planetary boundary layer (PBL) variables to anomalous initial volumetric soil moisture conditions. The experiments were conducted using three synoptic events: June 11, 17 and 22, 2006. For each event, one control run and six additional simulations were completed using RAMS and MM5. In each of the events, initial volumetric soil moisture was increased and decreased by 0.05, 0.10 and 0.15 m3m−3. Each of the events was individually analysed. Precipitation generally increased and decreased with enhanced and reduced soil moisture, respectively. Overall, RAMS simulations presented a greater sensitivity and variability in precipitation and PBL parameters. It was found that equivalent potential temperature, vertical wind velocities, and latent and sensible heat flux were helpful in explaining precipitation accumulation and distribution.