AN ANALYSIS OF A DIVERGENT MODEL FOR NUMERICAL FORECASTING
Abstract
A forecast model proposed by 'Arnason as being capable of producing realistic forecasts of displacement of systems at and below 500 mb was investigated. A prediction equation is applied to test cases at 1000, 850, 700 and 500 mb with various values of the parameter k1. The effect of the value of the parameter on the amount of divergence present in the model is discussed. Root-mean-square errors for 24-hour and 48-hour forecasts with various values of k1 at each level are presented. Optimum values of k1 for the cases tested are selected as 3.5, 2.75 and 0.9 for the levels 850, 700 and 500 mb respectively. It is found that with proper values for k1 the model will provide good forecasts of system movement at each level tested, but as expected, changes in the intensity of systems are not correctly forecast. In all cases values of root- mean-square error of forecasts are less than those obtained by applying the Helmholtz barotropic model. A geostrophic version of the model is also tested and is found to produce results similar to those obtained for the stream- function version except that the geostrophic blow-up of low-latitude high pressure cells is observed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1962
- Accession Number
- AD0282319
Entities
People
- Harry E. Nicholson
Organizations
- Naval Postgraduate School