Tropical Storm Movement Based on Synoptic Map Typing Using Empirical Orthogonal Functions.
Abstract
This initial study investigates the feasibility of using weather map types to forecast tropical storm/typhoon movement in the Western North Pacific Ocean. Fleet Numerical Oceanographic Center's hemispheric D-value analysis fields at 850, 700 and 500 mb are interpolated to a standard grid oriented relative to the present surface tropical storm position. Empirical Orthogonal Function (EOF) analysis is used to represent the fields in terms of only 10 coefficients in an effort to separate true synoptic map features from random noise. A least squares approach is then applied to determine characteristic synoptic patterns relative to the tropical storm, and to relate each individual cast to a 'map type'. An analog type approach is used to forecast the 30-, 36-, 54-, 60-, 78- and 84-hour positions. All storms determined to be of the same map type as the candidate storm were considered to be analogs, and their storm tracks were rotated to have the same past 12-hour movement. Forecast errors ranged from 135 n.mi. at 30 hours to 490 n.mi. at 84 hours. Although no independent cases were tested, and the techniques employed have not been optimized, the mean vector errors indicate that the basic technique warrants further investigation. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1981
- Accession Number
- ADA104591
Entities
People
- Danley W. Brown
Organizations
- Naval Postgraduate School