FINE SCALE EVALUATION OF TROPICAL WIND CLIMATOLOGIES USING A MASS CONSISTENT MODEL

摘要

High-resolution wind climatologies are needed for applications such as wind energy resource estimation and pollution modeling. The mass consistent wind model is an inexpensive model that may be used to generate detailed wind fields over complex terrains. While this model has been tested in several locations, no studies have been reported for the tropics at fine resolutions. Here, we report on the use of the ATHIN mass consistent wind model over Sri Lanka, an island (400km × 250km) with relatively high mountains (2,524m), in the tropical Asian monsoon region. Initially, we tuned the model over a synthetic Gaussian mountain topography under geostrophic wind fields similar to that experienced in Sri Lanka to estimate optimal input parameters such as atmospheric stability and transmissivity and adequate thresholds for residuals in the convergence of numerical solutions. We used these parameters along with available observation as inputs to the model to simulate monthly climatological wind fields with horizontal grid of 6-km and 50 unevenly spaced vertical levels to reach a height of 6-km. Realistic results were obtained for strong and weak southwest and north-east monsoon periods. The simulated wind climatologies were consistent with climatologies based on interpolation based on surface measurements at 20 synoptic stations and wind speeds estimated at 9 synoptic stations. The model capture high winds and complex variation in mountain passes which cannot be inferred from observations alone. There were discrepancies in the simulated wind speeds on the lee side of the mountains and in coastal areas. With these limitations, the model is useful for obtaining estimates of high-resolution surface and near-surface wind climatology fields.