MODIFICATION OF THE FJORTOFT GRAPHICAL PROGNOSIS METHOD.
This paper presents a relatively simple method for producing a 24-hour prognostic 500-mb chart by graphical means. It modifies the Fjortoft graphical method by incorporating a technique to include the intensification and weakening of systems. That is, it uses factors which allow intensification of p...
Main Authors: | , |
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Other Authors: | |
Format: | Text |
Language: | English |
Published: |
1966
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Online Access: | http://www.dtic.mil/docs/citations/AD0803354 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0803354 |
Summary: | This paper presents a relatively simple method for producing a 24-hour prognostic 500-mb chart by graphical means. It modifies the Fjortoft graphical method by incorporating a technique to include the intensification and weakening of systems. That is, it uses factors which allow intensification of poleward-moving cyclones and weakening of equatorward-moving cyclones and the converse for anti-cyclones. The theoretical development of the so-called 'geostrophic model' used, the research procedure, and a number of illustrative charts are all discussed and a table of chart verification scores is presented to assist in the reader's evaluation of the method. It is concluded that this method does provide a simple prognostic procedure which includes some intensity change for systems. The results showed an average 24.9% improvement over persistence for the charts analyzed using a height-gradient verification scheme. Appendix 1 outlines the specific procedure for utilizing the method on a practical basis and is included as such for the convenience of potential users. (Author) |
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