update on the uw-cimss advanced dvorak technique (adt) tim olander, chris velden and tony wimmers...

Update on the UW-CIMSSUpdate on the UW-CIMSSAdvanced Dvorak Technique Advanced Dvorak Technique

(ADT)(ADT)Tim Olander, Chris Velden Tim Olander, Chris Velden

and Tony Wimmersand Tony Wimmers

University of Wisconsin – MadisonUniversity of Wisconsin – MadisonCooperative Institute for Meteorological Cooperative Institute for Meteorological

Satellite Studies (CIMSS)Satellite Studies (CIMSS)

Meteorological Satellite (METSAT) ConferenceMeteorological Satellite (METSAT) ConferenceFord Island Conference CenterFord Island Conference Center

Pearl Harbor, HIPearl Harbor, HI27-28 April 200927-28 April 2009

Research supported by SPAWAR PEO C41&Space/PMW 180 and Research supported by SPAWAR PEO C41&Space/PMW 180 and the ONR Marine Meteorology Program via NRL-Montereythe ONR Marine Meteorology Program via NRL-Monterey

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)Presentation OverviewPresentation Overview

• Current StatusCurrent Status

• ADT Auto-Centering Technique ADT Auto-Centering Technique

• Experiments Incorporating Polar-Experiments Incorporating Polar-Orbiter Microwave DataOrbiter Microwave Data

• New Channel-Differencing TechniqueNew Channel-Differencing Technique• If time permitsIf time permits

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)ADT – Current StatusADT – Current Status

- Algorithm Version 7.2.3Algorithm Version 7.2.3 Latest fully- Latest fully-automated CIMSS-demonstrated version automated CIMSS-demonstrated version now operational at NESDIS-SAB.now operational at NESDIS-SAB.

- Algorithm Version 8.0Algorithm Version 8.0 Latest experimental Latest experimental version will be run simultaneously with 7.2.3 version will be run simultaneously with 7.2.3 at CIMSS this coming TC season, and at CIMSS this coming TC season, and perhaps at SAB as well. Real-time intensity perhaps at SAB as well. Real-time intensity estimates will be available via CIMSS web estimates will be available via CIMSS web site, and/or ATCF.site, and/or ATCF.

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)ADT Auto-CenteringADT Auto-Centering

Current ADT AutomatedCurrent ADT AutomatedStorm Center Determination Storm Center Determination

AlgorithmAlgorithm


Initial Storm Center DeterminationInitial Storm Center Determination• Utilize Infrared Window (IR) Channel ImageryUtilize Infrared Window (IR) Channel Imagery

» Works with any geostationary satellite IR imageryWorks with any geostationary satellite IR imagery

• Spiral CenteringSpiral Centering» ““First guess” center position interpolated from TC forecast (JT or NHC)First guess” center position interpolated from TC forecast (JT or NHC)» Fits 5Fits 5° log spiral vector field to the IR image (entire TC cloud top temps)° log spiral vector field to the IR image (entire TC cloud top temps)» Calculates a grid of scores that indicates the alignment between the spiral field Calculates a grid of scores that indicates the alignment between the spiral field

and the IR Tb gradients (maximum at the spiral center)and the IR Tb gradients (maximum at the spiral center)» Spiral centering scores modified based on distance from first guessSpiral centering scores modified based on distance from first guess» If modified score exceeds empirically-derived threshold, position is usedIf modified score exceeds empirically-derived threshold, position is used

• Ring Fitting (if IR-determined eye present)Ring Fitting (if IR-determined eye present)» Spiral centering maximum serves as first guess center positionSpiral centering maximum serves as first guess center position» Calculates a grid of scores that indicates the best fit (Tb gradients) to a range of Calculates a grid of scores that indicates the best fit (Tb gradients) to a range of

possible ring positions and diameters (maximum at the eye center)possible ring positions and diameters (maximum at the eye center)» If score exceeds empirically-derived threshold, position is usedIf score exceeds empirically-derived threshold, position is used» Additional logic to identify and avoid “false eye” (moat) regionsAdditional logic to identify and avoid “false eye” (moat) regions

• Combined Analysis (if a Ring Score is successful)Combined Analysis (if a Ring Score is successful)» Finds ‘final’ position where the sum of the spiral and ring scores is greatestFinds ‘final’ position where the sum of the spiral and ring scores is greatest


Spiral CenteringSpiral Centering• Fits 5° log spiral vector Fits 5° log spiral vector field to the IR Tb imagefield to the IR Tb image

• Calculates a grid of Calculates a grid of scores that indicates the scores that indicates the alignment between the alignment between the spiral field and the IR Tb spiral field and the IR Tb gradients (maximum at gradients (maximum at the spiral center)the spiral center)

Ring FittingRing Fitting• Calculates a grid of Calculates a grid of scores that indicates scores that indicates the best fit to a range the best fit to a range of possible ring of possible ring positions and positions and diameters (maximum diameters (maximum at the eye center)at the eye center)


Super Typhoon 20PSuper Typhoon 20P(Percy)(Percy)

27 February 200527 February 200511:25 UTC11:25 UTC

GOES-10GOES-10

Spiral Centering

Ring Fitting Combined Method

Official ForecastOfficial Forecast““First Guess”First Guess”

Spiral AnalysisSpiral AnalysisCenterCenter

““coarse fit”coarse fit”

Best Ring FitBest Ring Fit““fine adjustment”fine adjustment”

Final ADTFinal ADTStorm CenterStorm Center

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)Experimental MW-Based AnalysisExperimental MW-Based Analysis

Microwave TC Centering MethodologyMicrowave TC Centering Methodology• Utilize Microwave 85-92GHz imageryUtilize Microwave 85-92GHz imagery

» SSMI, SSMIS, AMSRE, and TMI SSMI, SSMIS, AMSRE, and TMI » Also utilizes an official forecast Vmax from JT/NHC as inputAlso utilizes an official forecast Vmax from JT/NHC as input

• MotivationMotivation» Spiral and ring centering is more effective in MW (compared to IR) Spiral and ring centering is more effective in MW (compared to IR)

especially during CDO situationsespecially during CDO situations• OverallOverall

» Follows same general methodology as IR auto-centering Follows same general methodology as IR auto-centering technique described earlier technique described earlier

» Main differences limited to internal weights/threshold valuesMain differences limited to internal weights/threshold values» And unlike the IR method, the algorithm internal parameters vary And unlike the IR method, the algorithm internal parameters vary

with the first-guess Vmax (looser with low Vmax, stricter with high with the first-guess Vmax (looser with low Vmax, stricter with high Vmax)Vmax)

• This algorithm is not yet directly a part of the ADT input, This algorithm is not yet directly a part of the ADT input, but may become so in a future ADT versionbut may become so in a future ADT version

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)Experimental MW-based AnalysisExperimental MW-based Analysis

Legend: Δ Official Best Track + First Guess □ Final Answer

Maximum is eye center positionestimate

Initial MW image MW Close Up

Spiral AnalysisScore Field

Combined AnalysisScore Field

Ring AnalysisScore Field

TRMM TMITRMM TMI

21 August 200721 August 200722:19 UTC22:19 UTC

Best Track Vmax: 71ktsBest Track Vmax: 71kts

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)Experimental MI AnalysisExperimental MI Analysis

Experimental Objective Experimental Objective Microwave-based Intensity (MI) Microwave-based Intensity (MI)

Determination AlgorithmDetermination Algorithm

Background and MotivationBackground and Motivation

• Experimental ADT algorithm V8.0 utilizes external passive microwave Experimental ADT algorithm V8.0 utilizes external passive microwave information from polar orbiters to aid in detection of tropical cyclone eye information from polar orbiters to aid in detection of tropical cyclone eye formation when objective IR-based scene identification schemes cannot formation when objective IR-based scene identification schemes cannot discern an eye feature. discern an eye feature.

• The current ADT algorithm struggles with situations where high-level cirrus The current ADT algorithm struggles with situations where high-level cirrus (from tropical cyclone convection) can obscure the IR sensor from (from tropical cyclone convection) can obscure the IR sensor from observing the formation of an eye feature in developing TCs. MW data observing the formation of an eye feature in developing TCs. MW data can observe through the cirrus to the convective cloud structure below in can observe through the cirrus to the convective cloud structure below in most cases.most cases.


Infrared Image Infrared Image 09 Sept 2008 /17:30UTC09 Sept 2008 /17:30UTC

No Eye Apparent in IR Imagery

““Dvorak” EnhancementDvorak” Enhancement09 Sept 2008 /17:30UTC09 Sept 2008 /17:30UTC

Microwave Image – AMSREMicrowave Image – AMSRE09 Sept 2008 /17:08:28UTC09 Sept 2008 /17:08:28UTC

Eye Region DepictedIn MW Imagery


Experimental Passive MW Intensity Estimation ApproachExperimental Passive MW Intensity Estimation Approach Purely objective and automatedPurely objective and automated Currently utilized only in developing TCs with emerging eyesCurrently utilized only in developing TCs with emerging eyes

SummarySummary

• Uses MW 85-92 GHz Uses MW 85-92 GHz brightness temperature brightness temperature structure in the TC core region structure in the TC core region

• Provides intensity estimate Provides intensity estimate categories for developing TCs categories for developing TCs

• < 65 knots< 65 knots• 65-85 knots65-85 knots• > 85 knots> 85 knots

• Has been tested as ADT input Has been tested as ADT input since early 2008since early 2008

Warmest eye pixel

Eyewall temperatures

Hurricane Dolly, 23 July 2008 1126 UTCHurricane Dolly, 23 July 2008 1126 UTC

DMSP SSM/I 85GHz (H) brightness temperature



Max Wind Speed Estimate DeterminationMax Wind Speed Estimate Determination• Calculate two “discriminator” valuesCalculate two “discriminator” values

» ““Tb Difference” Tb Difference” ◦ Maximum temperature difference between warmest pixels in eye and Maximum temperature difference between warmest pixels in eye and

eyewall regions (similar to Dvorak EIR)eyewall regions (similar to Dvorak EIR)» ““Completeness” of eye wall Completeness” of eye wall (higher of two values)(higher of two values)

◦ Fraction of pixels : (TbFraction of pixels : (Tbeyeeye - Tb - Tbeyewalleyewall) > 20K) > 20K◦ Fraction of pixels < 232KFraction of pixels < 232K

• Final ‘Score’: combination of two valuesFinal ‘Score’: combination of two values» ““Tb Difference” scoreTb Difference” score: : +1 score pt+1 score pt for every 1 for every 1° ° Tb differenceTb difference» ““Completeness” scoreCompleteness” score: >.85, add : >.85, add 15 score points15 score points» 00 (no eyewall) (no eyewall) to to 100+100+ (strong eyewall)(strong eyewall)

• ScoreScore between 20 – 60between 20 – 60 : : likely abovelikely above 65 knots65 knots• ScoreScore greater than 60greater than 60 : : likely abovelikely above 85 knots85 knots

The microwave module has been validated in the Atlantic

• Validation of microwave Validation of microwave estimates on an independent estimates on an independent sample of Atlantic hurricanes sample of Atlantic hurricanes (recon-aided Best Track) (recon-aided Best Track) shows that the microwave shows that the microwave module makes reliable, module makes reliable, conservative estimates of conservative estimates of cyclone intensity for the cyclone intensity for the critical Vmax thresholds of critical Vmax thresholds of >65 knots and >85 knots. >65 knots and >85 knots.



• MI eye score is calculated and passed to the ADTMI eye score is calculated and passed to the ADT» Input is controlled via automated parameter valuesInput is controlled via automated parameter values

• ADT uses this score value to reset the current intensity of the storm ADT uses this score value to reset the current intensity of the storm (time of MI data) to one of two values(time of MI data) to one of two values» MI value : 65-85 knotsMI value : 65-85 knots ADT T# = 4.5 ADT T# = 4.5 (77 kts)(77 kts)» MI value : > 85 knotsMI value : > 85 knots ADT T# = 5.2 ADT T# = 5.2 (94 kts)(94 kts)

• Value will then be “merged” value into the ADT storm history fileValue will then be “merged” value into the ADT storm history file» IR-based Adjusted Raw T#, Final T# and CI# values are modified over IR-based Adjusted Raw T#, Final T# and CI# values are modified over

previous 12 hours via linear interpolation previous 12 hours via linear interpolation » Original (IR) Raw T# values from ADT are left alone for post analysisOriginal (IR) Raw T# values from ADT are left alone for post analysis» Avoids unnatural intensity jumps in the recordAvoids unnatural intensity jumps in the record

• Once an eye scene appears in three consecutive ADT IR-based Once an eye scene appears in three consecutive ADT IR-based analyses, MI values are no longer used (ADT does well with these analyses, MI values are no longer used (ADT does well with these scene types, and the MI intensity estimate precision declines after scene types, and the MI intensity estimate precision declines after the TC eye formation stage (work in progress))the TC eye formation stage (work in progress))

Validation of Experimental ADT Version with MI

MSLP (units : hPa) Bias RMSE Abs. Err.

ADT – Operational 4.09 11.61 9.01

ADT – w/ MI adj. 3.18 10.70 8.11

2008 Atlantic Season TC intensity estimates versus aircraft reconnaissance

299 matches – Independent Sample

Vmax (units : m/s) Bias RMSE Abs. Err.

ADT – Operational -3.72 8.23 6.40

ADT – w/ MI adj. -2.98 7.78 5.84



Eliminated false intensity Eliminated false intensity plateau; Closer to Best Track plateau; Closer to Best Track maximum intensitymaximum intensity

More closely follows More closely follows rapid intensification; rapid intensification; More accurate maximum More accurate maximum intensity resultedintensity resulted

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)SummarySummary

• Experimental ADT w/ MI EstimatesExperimental ADT w/ MI Estimates

» MI technique is now fully functional within MI technique is now fully functional within experimental (ver 8.0) ADTexperimental (ver 8.0) ADT

» Real time output will appear on the CIMSS TC Real time output will appear on the CIMSS TC web site during the 2009 TC season (can also web site during the 2009 TC season (can also be made available on ATCF for JTWC analysis)be made available on ATCF for JTWC analysis)

» Plan to also implement experimentally at Plan to also implement experimentally at NOAA/SAB during 2009 season for NOAA/SAB during 2009 season for independent assessmentindependent assessment

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)ADT Access InformationADT Access Information

• ADT Real-Time EstimatesADT Real-Time Estimates» http://cimss.ssec.wisc.edu/tropic2/real-time/adthttp://cimss.ssec.wisc.edu/tropic2/real-time/adt

◦ Global TC coverageGlobal TC coverage◦ Completely automatedCompletely automated

• ADT Overview and ArchiveADT Overview and Archive» http://cimss.ssec.wisc.edu/tropic2/misc/adthttp://cimss.ssec.wisc.edu/tropic2/misc/adt

◦ Online publications and technique historyOnline publications and technique history◦ Storm archive from 2003 to currentStorm archive from 2003 to current

Or just go to the CIMSS Tropical Cyclone webpage at :Or just go to the CIMSS Tropical Cyclone webpage at :

http://cimss.ssec.wisc.edu/tropic2http://cimss.ssec.wisc.edu/tropic2and click on “Our Research / ADT”and click on “Our Research / ADT”

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)ThanksThanks

The UW-CIMSS TC Research Group again The UW-CIMSS TC Research Group again thanks Jeff Hawkins from NRL-MRY and thanks Jeff Hawkins from NRL-MRY and

the ONR and SPAWAR sponsors for their the ONR and SPAWAR sponsors for their continuing and committed support for this continuing and committed support for this work, and the operational units at JTWC, work, and the operational units at JTWC,

SAB and NHC for their constructive SAB and NHC for their constructive feedback and evaluationfeedback and evaluation

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)Looking AheadLooking Ahead

Looking Ahead -Looking Ahead -An Additional Multispectral An Additional Multispectral

ADT Enhancement? :ADT Enhancement? :Infrared Window – Water Vapor Infrared Window – Water Vapor

Channel DifferencingChannel Differencing

Advanced Dvorak Technique (ADT)Advanced Dvorak Technique (ADT)IR-WV Channel DifferencingIR-WV Channel Differencing

• IR-WV difference field IR-WV difference field easy to compute/analyze; easy to compute/analyze; Derived imagery easy to Derived imagery easy to examine qualitativelyexamine qualitatively

• Derived IRWV field canDerived IRWV field can aid in storm centeraid in storm center determinationdetermination

• Can provide better Can provide better information on regions of information on regions of strongest convectionstrongest convection and and trendstrends

• Correlations between TC Correlations between TC core-averaged IRWV core-averaged IRWV signal and observed signal and observed intensity exhibit intensity exhibit predictive predictive qualityquality, especially in 12-24 , especially in 12-24 hour rangehour range

IR Image

Derived IR-WV ImageIR Image (w/ BD enh)

Stretched IR Image(IR-WV locations only)

update on the uw-cimss advanced dvorak technique (adt) tim olander, chris velden and tony wimmers...

Documents

ir autocentering technique

spiral field

ring centering

ir tb gradients maximum

grid of scores

ir tb imagecalculates

log spiral vector field

diameters maximum