Update on the UW-CIMSS Advanced Dvorak Technique (ADT) Tim Olander, Chris Velden and Tony Wimmers University of Wisconsin – Madison Cooperative Institute for Meteorological Satellite Studies (CIMSS) Meteorological Satellite (METSAT) Conference Ford Island Conference Center Pearl Harbor, HI April 2009 Research supported by SPAWAR PEO C41&Space/PMW 180 and the ONR Marine Meteorology Program via NRL-Monterey

Advanced Dvorak Technique (ADT) Presentation Overview Current StatusCurrent Status ADT Auto-Centering TechniqueADT Auto-Centering Technique Experiments Incorporating Polar- Orbiter Microwave DataExperiments Incorporating Polar- Orbiter Microwave Data New Channel-Differencing TechniqueNew Channel-Differencing Technique If time permitsIf time permits

Advanced Dvorak Technique (ADT) ADT – Current Status - Algorithm Version Latest fully- automated CIMSS-demonstrated version now operational at NESDIS-SAB. - Algorithm Version 8.0 Latest experimental version will be run simultaneously with at CIMSS this coming TC season, and perhaps at SAB as well. Real-time intensity estimates will be available via CIMSS web site, and/or ATCF.

Advanced Dvorak Technique (ADT) ADT Auto-Centering Current ADT Automated Storm Center Determination Algorithm

Advanced Dvorak Technique (ADT) ADT Auto-Centering Initial Storm Center Determination Utilize Infrared Window (IR) Channel ImageryUtilize Infrared Window (IR) Channel Imagery »Works with any geostationary satellite IR imagery Spiral CenteringSpiral Centering »“First guess” center position interpolated from TC forecast (JT or NHC) »Fits 5° 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 and the IR Tb gradients (maximum at the spiral center) »Spiral centering scores modified based on distance from first guess »If 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 position »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) »If score exceeds empirically-derived threshold, position is used »Additional 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 greatest

Advanced Dvorak Technique (ADT) ADT Auto-Centering Spiral Centering Fits 5° log spiral vector field to the IR Tb imageFits 5° log spiral vector field to the IR Tb image Calculates a grid of scores that indicates the alignment between the spiral field and the IR Tb gradients (maximum at the spiral center)Calculates a grid of scores that indicates the alignment between the spiral field and the IR Tb gradients (maximum at the spiral center) Ring Fitting Calculates a grid of scores that indicates the best fit to a range of possible ring positions and diameters (maximum at the eye center)Calculates a grid of scores that indicates the best fit to a range of possible ring positions and diameters (maximum at the eye center)

Advanced Dvorak Technique (ADT) ADT Auto-Centering Super Typhoon 20P (Percy) 27 February :25 UTC GOES-10 Spiral Centering Ring FittingCombined Method Official Forecast “First Guess” Spiral Analysis Center “coarse fit” Best Ring Fit “fine adjustment” Final ADT Storm Center

Advanced Dvorak Technique (ADT) Experimental MW-Based Analysis Microwave TC Centering Methodology Utilize Microwave 85-92GHz imageryUtilize Microwave 85-92GHz imagery »SSMI, SSMIS, AMSRE, and TMI »Also utilizes an official forecast Vmax from JT/NHC as input MotivationMotivation »Spiral and ring centering is more effective in MW (compared to IR) especially during CDO situations OverallOverall »Follows same general methodology as IR auto-centering technique described earlier »Main differences limited to internal weights/threshold values »And unlike the IR method, the algorithm internal parameters vary with the first-guess Vmax (looser with low Vmax, stricter with high Vmax) This algorithm is not yet directly a part of the ADT input, but may become so in a future ADT versionThis algorithm is not yet directly a part of the ADT input, but may become so in a future ADT version

Advanced Dvorak Technique (ADT) Experimental MW-based Analysis Legend: Δ Official Best Track + First Guess □ Final Answer Maximum is eye center position estimate Initial MW image MW Close Up Spiral Analysis Score Field Combined Analysis Score Field Ring Analysis Score Field TRMM TMI 21 August :19 UTC Best Track Vmax: 71kts

Advanced Dvorak Technique (ADT) Experimental MI Analysis Experimental Objective Microwave-based Intensity (MI) Determination Algorithm

Background and Motivation Experimental ADT algorithm V8.0 utilizes external passive microwave information from polar orbiters to aid in detection of tropical cyclone eye formation when objective IR-based scene identification schemes cannot discern an eye feature.Experimental ADT algorithm V8.0 utilizes external passive microwave information from polar orbiters to aid in detection of tropical cyclone eye formation when objective IR-based scene identification schemes cannot discern an eye feature. The current ADT algorithm struggles with situations where high-level cirrus (from tropical cyclone convection) can obscure the IR sensor from observing the formation of an eye feature in developing TCs. MW data can observe through the cirrus to the convective cloud structure below in most cases.The current ADT algorithm struggles with situations where high-level cirrus (from tropical cyclone convection) can obscure the IR sensor from observing the formation of an eye feature in developing TCs. MW data can observe through the cirrus to the convective cloud structure below in most cases. Advanced Dvorak Technique (ADT) Experimental MI Analysis

Infrared Image 09 Sept 2008 /17:30UTC No Eye Apparent in IR Imagery “Dvorak” Enhancement 09 Sept 2008 /17:30UTC Microwave Image – AMSRE 09 Sept 2008 /17:08:28UTC Eye Region Depicted In MW Imagery Advanced Dvorak Technique (ADT) Experimental MI Analysis

Experimental Passive MW Intensity Estimation Approach Experimental Passive MW Intensity Estimation Approach  Purely objective and automated  Currently utilized only in developing TCs with emerging eyes Summary Uses MW GHz brightness temperature structure in the TC core region Uses MW GHz brightness temperature structure in the TC core region Provides intensity estimate categories for developing TCs Provides intensity estimate categories for developing TCs < 65 knots < 65 knots knots knots > 85 knots > 85 knots Has been tested as ADT input since early 2008 Has been tested as ADT input since early 2008 Warmest eye pixel Eyewall temperatures Hurricane Dolly, 23 July UTC DMSP SSM/I 85GHz (H) brightness temperature Advanced Dvorak Technique (ADT) Experimental MI Analysis

Advanced Dvorak Technique (ADT) Experimental MI Analysis Max Wind Speed Estimate Determination Calculate two “discriminator” valuesCalculate two “discriminator” values »“Tb Difference” ◦Maximum temperature difference between warmest pixels in eye and eyewall regions (similar to Dvorak EIR) »“Completeness” of eye wall (higher of two values) ◦Fraction of pixels : (Tb eye - Tb eyewall ) > 20K ◦Fraction of pixels < 232K Final ‘Score’: combination of two valuesFinal ‘Score’: combination of two values »“Tb Difference” score: +1 score pt for every 1° Tb difference »“Completeness” score: >.85, add 15 score points » 0 (no eyewall) to 100+ (strong eyewall) Score between 20 – 60 : likely above 65 knotsScore between 20 – 60 : likely above 65 knots Score greater than 60 : likely above 85 knotsScore greater than 60 : likely above 85 knots

The microwave module has been validated in the Atlantic Validation of microwave estimates on an independent sample of Atlantic hurricanes (recon-aided Best Track) shows that the microwave module makes reliable, conservative estimates of cyclone intensity for the critical Vmax thresholds of >65 knots and >85 knots. Validation of microwave estimates on an independent sample of Atlantic hurricanes (recon-aided Best Track) shows that the microwave module makes reliable, conservative estimates of cyclone intensity for the critical Vmax thresholds of >65 knots and >85 knots. Advanced Dvorak Technique (ADT) Experimental MI Analysis

Advanced Dvorak Technique (ADT) Experimental MI Analysis 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 values ADT uses this score value to reset the current intensity of the storm (time of MI data) to one of two valuesADT uses this score value to reset the current intensity of the storm (time of MI data) to one of two values »MI value : knots  ADT T# = 4.5 (77 kts) »MI value : > 85 knots  ADT T# = 5.2 (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 previous 12 hours via linear interpolation »Original (IR) Raw T# values from ADT are left alone for post analysis »Avoids unnatural intensity jumps in the record Once an eye scene appears in three consecutive ADT IR-based analyses, MI values are no longer used (ADT does well with these scene types, and the MI intensity estimate precision declines after the TC eye formation stage (work in progress))Once an eye scene appears in three consecutive ADT IR-based analyses, MI values are no longer used (ADT does well with these scene types, and the MI intensity estimate precision declines after the TC eye formation stage (work in progress))

Validation of Experimental ADT Version with MI MSLP (units : hPa) BiasRMSEAbs. Err. ADT – Operational ADT – w/ MI adj Atlantic Season TC intensity estimates versus aircraft reconnaissance 299 matches – Independent Sample Vmax (units : m/s) BiasRMSEAbs. Err. ADT – Operational ADT – w/ MI adj Advanced Dvorak Technique (ADT) Experimental MI Analysis

Advanced Dvorak Technique (ADT) Experimental MI Analysis Eliminated false intensity plateau; Closer to Best Track maximum intensity More closely follows rapid intensification; More accurate maximum intensity resulted

Advanced Dvorak Technique (ADT) Summary Experimental ADT w/ MI EstimatesExperimental ADT w/ MI Estimates »MI technique is now fully functional within experimental (ver 8.0) ADT »Real time output will appear on the CIMSS TC web site during the 2009 TC season (can also be made available on ATCF for JTWC analysis) »Plan to also implement experimentally at NOAA/SAB during 2009 season for independent assessment

Advanced Dvorak Technique (ADT) ADT Access Information ADT Real-Time EstimatesADT Real-Time Estimates » ◦Global TC coverage ◦Completely automated ADT Overview and ArchiveADT Overview and Archive » ◦Online publications and technique history ◦Storm archive from 2003 to current Or just go to the CIMSS Tropical Cyclone webpage at : and click on “Our Research / ADT”

Advanced Dvorak Technique (ADT) Thanks The UW-CIMSS TC Research Group again thanks Jeff Hawkins from NRL-MRY and the ONR and SPAWAR sponsors for their continuing and committed support for this work, and the operational units at JTWC, SAB and NHC for their constructive feedback and evaluation

Advanced Dvorak Technique (ADT)

Looking Ahead Looking Ahead - An Additional Multispectral ADT Enhancement? : Infrared Window – Water Vapor Channel Differencing

Advanced Dvorak Technique (ADT) IR-WV Channel Differencing Water Vapor IR Window Water Vapor IR Window 300K 180K IR Window brightness temps are warmer than Water Vapor temps in the troposphereIR Window brightness temps are warmer than Water Vapor temps in the troposphere In regions of intense convection (i.e. TC eyewalls), above-cloud water vapor can penetrate into the stratosphere and actually irradiate warmer in the WV channel than the IR-WIn regions of intense convection (i.e. TC eyewalls), above-cloud water vapor can penetrate into the stratosphere and actually irradiate warmer in the WV channel than the IR-W Derived IR-WV difference fields can be used qualitatively and quantitatively to assess tropical cyclone intensity changesDerived IR-WV difference fields can be used qualitatively and quantitatively to assess tropical cyclone intensity changes Journal article detailing technique currently in review processJournal article detailing technique currently in review process

Advanced Dvorak Technique (ADT) IR-WV Channel Differencing IR-WV difference field easy to compute/analyze; Derived imagery easy to examine qualitativelyIR-WV difference field easy to compute/analyze; Derived imagery easy to examine qualitatively Derived IRWV field can aid in storm center determinationDerived IRWV field can aid in storm center determination Can provide better information on regions of strongest convection and trendsCan provide better information on regions of strongest convection and trends Correlations between TC core-averaged IRWV signal and observed intensity exhibit predictive quality, especially in hour rangeCorrelations between TC core-averaged IRWV signal and observed intensity exhibit predictive quality, especially in hour range IR Image Derived IR-WV ImageIR Image (w/ BD enh) Stretched IR Image (IR-WV locations only)

Advanced Dvorak Technique (ADT) IR-WV Channel Differencing CDO scenes during formation No Lag 6hr Lag 12hr Lag 18hr Lag 24hr Lag Tb IR only ADT current Tb IR-WV ADT + Tb IR-WV # matches Preliminary Quantitative Analysis IRWV difference product appears to add skill to the ADT as a current intensity estimator, and has higher correlations with recon-validated intensity at 12-24hr lag times (predictive quality to IRWV field?)IRWV difference product appears to add skill to the ADT as a current intensity estimator, and has higher correlations with recon-validated intensity at 12-24hr lag times (predictive quality to IRWV field?) 12-hr Lag – All Scenes

Advanced Dvorak Technique (ADT) IR-WV Channel Differencing