Advanced Objective Dvorak Technique AODT

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Advanced Objective Dvorak Technique (AODT)

• Christopher Velden and Timothy Olander
• University of Wisconsin-Madison
• Cooperative Institute for Meteorological
  Satellite Studies
• Research and development funding provided by
• Naval Research Laboratory - Monterey, CA
• Funding contract N00173-01-C-2024 through
• Space and Naval Warfare Systems Command (PMW-155)
  
• under PE 0603207N

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Advanced Objective Dvorak Technique (AODT)

• AODT algorithm objectively estimates tropical
  cyclone intensity
• Utilizes global, geostationary, longwave infrared
  channel satellite imagery
• Based on Dvorak Technique procedures, rules, and
  techniques
• User only needs to determine/input storm center
  location
• Objectively determines type of scene being
  examined, applies rules based on these scene
  types (e.g. eye/no eye, undergoing shear,
  formation stage)
• Applies time-weighted averaging scheme and
  various time-dependent intensity change rules to
  account for documented biases in technique
• Strengths
• AODT removes inherent subjectivity of operational
  Dvorak Technique.
• Can be used to estimate storm intensity of any
  tropical cyclone worldwide.
• Proven statistically to be superior to previous
  objective techniques and equal in skill with
  estimates obtained from experienced forecasters
• Ease of use Can be used by novice forecasters
• Weaknesses
• Inaccurate intensity estimates if objective scene
  identification scheme fails
• Technique based on typical storm evolution, may
  not handle
• extreme or non-tropical cases correctly.

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Advanced Objective Dvorak Technique (AODT)

• Significant Algorithm Upgrades
• Expanded intensity analysis to include entire
  storm lifecycle
• Added Curved Band analysis for tropical
  depressions/tropical storms
• Auto-center finding algorithm added to aid
  forecasters
• Center fix determined from forecast positions and
  image analysis techniques
• Implemented additional intensity growth/decay
  constraint rules
• Rule 8 in original EIR/Visible Dvorak Technique
• Added latitude bias correction to final intensity
  estimate
• Based upon linear regression analysis of data set
• Reduces RMS error by about 10 over previous ODT
  versions
• Additional Modifications
• Changed Cloud Region Temperature calculation
• Better determine eyewall convection
  characteristics (strength, symmetry)
• Reduce contamination of temperature calculation
  with eye region values
• Improved scene identification schemes
• Added more scene types for eye and non-eye cases
• Modified land feature interaction check

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Advanced Objective Dvorak Technique (AODT)
26 individual tropical cyclones 1995-2002
AODT results improved over previous ODT
version and on par with Operational Center
Estimates
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New Eye Scene Classifications
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New Cloud Scene Classifications