A Diagnostic Model for Estimating Orographic Precipitation
- 1 October 1994
- journal article
- Published by American Meteorological Society in Journal of Applied Meteorology and Climatology
- Vol. 33 (10) , 1163-1175
- https://doi.org/10.1175/1520-0450(1994)033<1163:admfeo>2.0.co;2
Abstract
A simple model for estimating detailed orographic precipitation is presented. The model is initialized using coarse-resolution analyses from the European Centre for Medium-Range Weather Forecasts and is applied to the heavy rainfall over northern New Zealand from Tropical Cyclone Bola (March 1988). The model is based on the estimation of topographically forced vertical motion as V·∇zs, where zs is the height of the topography and V is the horizontal flow just upstream of the mountain. Model skill is evaluated by computing the correlation coefficient rg of the model results against 297 rain gauge measurements. Enhancement of the model by adding lee drying, wind drift effects, and modulation by larger-scale humidity and vertical-motion fields each led to a statistically significant increase in rg. Best results were obtained at a resolution near 10 km, for which an rg of 0.84 was obtained. However, ignoring drift effects at 25-km resolution resulted in model skill nearly equivalent to the full model at 10 km, highlighting the need to demonstrate that supposed model improvements do, in fact, lead to significant increases in skill.Keywords
This publication has 0 references indexed in Scilit: