Extended Abstract (32K)8A.4
The Advanced Objective Dvorak Technique (AODT)—Continuing the Journey
Timothy L. Olander, CIMSS/Univ. of Wisconsin, Madison, WI; and C. S. Velden
A methodology to estimate tropical cyclone (TC) intensity using geostationary satellite data was developed during the 1970's, led by Vern Dvorak at NOAA/NESDIS. This technique, known as the Dvorak Technique (DT), has been used by operational hurricane forecasting centers worldwide, and is relied upon by forecasters in regions where aircraft reconnaissance is not available. However, this technique can be subjective and difficult to learn/use by less experienced TC forecasters. With the advent of interactive satellite data display systems and technological advances in computing resources, the development of an objective DT-based satellite data analysis technique was made possible. Dvorak outlined the original objective technique in the mid 1980's using enhanced geostationary longwave infrared (EIR) data. Further advances to Dvorak's technique were developed in the late 1980's and early 1990's as analysis of global satellite data became more widely available. Emerging from these efforts, an initial objective DT algorithm was developed primarily by Ray Zehr of NOAA/NESDIS (see companion abstract for this session).
In the mid 1990's, scientists at the University of Wisconsin/Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS) began an effort to reconstruct the DT within a computer-based environment. The prototype design, the UW-CIMSS Objective Dvorak Technique (ODT), was developed as a first step along this research path. The goal of the ODT was to attempt to mimic the original DT through direct implementation of its various rules and logic schemes. Development of objective scene type analysis and time averaging of ODT intensity estimates were the most important advancements of this algorithm. Transition of the ODT to operational use at various TC forecasting centers began in the late 1990's, however use of the ODT was limited to tropical cyclones of hurricane/typhoon strength, and still relied upon the user to manually select the storm center location. The next step in the development of the ODT was to expand the capabilities while integrating new techniques and developing technologies into the current objective techniques. This was achieved with development of the Advanced ODT (AODT), which expands the range of its intensity analysis to operate over the entire TC lifecycle, and removes the subjectivity introduced to the technique by manual storm center positioning while preserving the accuracy of the ODT. Comparisons of AODT and operational DT intensity estimates with aircraft reconnaissance show the AODT to be on par with the operational DT at the TC forecast centers.
With the AODT benchmarked and transitioning into operational TC centers worldwide, the next step will be the most ambitious. This step involves merging the AODT with additional TC intensity estimation techniques utilizing multispectral channels (i.e. microwave) from multi-platform sources. A unified satellite-based algorithm that will combine the strengths of each instrument and technique into an "expert system" is the ultimate goal.
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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