Evaluation of WRF near-surface wind simulations in tropics employing different planetary boundary layer schemes

Abstract

This paper evaluates performances of WRF's planetary boundary layer (PBL) schemes for simulating near-surface winds in northeastern Thailand using hourly observed wind speeds and directions at 65 and 90 m above ground for 3 full months from 12 and 9 wind measuring stations, respectively. NCEP final analyses are used for initial and boundary conditions. Simulations are restarted every 12 h with 6-h spin up periods. Grid nudging is used for altitudes above PBL. WRF wind fields at 5-km resolution are used for accuracy evaluation. Vertical interpolations for wind speed and direction are logarithmic and linear, respectively. Results show that simulation accuracies are sensitive to the PBL scheme. The Bretherton and Park (UW) PBL scheme together with the Revised MM5 Monin-Obukhov surface layer scheme and the Unified Noah land surface model performs best. The UW-simulated wind speeds agree well with observations at both altitudes and have good utility for wind speeds above 2 m/s. The UW-simulated wind directions agree well with observations. The wind simulation system presented in this paper is useful for wind energy development in northeastern Thailand.