Extended Abstract (32K)8A.3
The Objective Dvorak Technique—historical perspective
Raymond Zehr, NOAA/NESDIS, Fort Collins, CO
When satellite images first became available in the 1960’s, identification and tracking of intense hurricanes became a trivial task due to the easily identifiable hurricane eye. However, tracking weaker tropical cyclones and finding a reliable way of estimating the intensity, were much more challenging problems. Scientists at NOAA/NESDIS led by Vern Dvorak, aided by the improving quality of geostationary satellite images in the 1970’s, developed satellite applications specifically aimed at operational forecasting of tropical cyclones. By 1975, a methodology for estimating intensity based on cloud pattern evolution was published. That procedure came to be known as the Dvorak Technique and was supplemented by 1984 with the enhanced infrared (EIR) method for independently assigning hurricane intensity. The original objective Dvorak technique was adapted from the EIR method and published by Dvorak in 1984. Since that time, applications development has continued within NESDIS and CIMSS, with modifications and enhancements to Dvorak’s original objective IR measurements. The Dvorak technique continues to be widely used operationally throughout the world. This long term usage with better quality images and animation, along with improved validation measurements, have provided considerable insight on the strengths and weaknesses of the Dvorak technique. The present ODT algorithms continue to evolve and additional improvements are anticipated. Microwave observations from polar orbiters have shown the capability of providing independent intensity estimates to supplement the ODT, however they are limited by observation frequency and timeliness.
The goal of this paper is to present some detailed historical information on ODT measurements, and their evaluation. Results from the new version of the CIMSS AODT (Advanced Objective Dvorak Technique) will be presented. Future potential IR applications will be briefly summarized. For example, preliminary results support the possibility of developing algorithms for radius of maximum wind, radial wind distribution, pressure-wind relationships, and onset of rapid intensification.
Session 8A, 30 years of the dvorak technique: Part II
Tuesday, 4 May 2004, 3:45 PM-4:55 PM, Le Jardin Room
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