Joint Typhoon Warning CenterTropical Cyclone Best Track

Processes

International Best Track Archive for Climate Stewardship Workshop

5-7 May 2009Asheville NC

Mr. Bob FalveyDirector, Joint Typhoon Warning Center

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Background

Established in 1 May 1959 to protect DoD

assets

Nimitz Hill, GU until 1999, now Pearl Harbor, HI

United States Pacific Command Instruction

0539.1 established requirements

United States Air Force conducts TC

reconnaissance and provides personnel

United States Navy provides facilities,

equipment, and personnel

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JTWC Mission

Provide tropical cyclone forecast and warning support for Department of Defense, Department of State and US Government assets in the Pacific and Indian Oceans as established by Commander, United States Pacific Command

Airmen from the 18th Aircraft Maintenance Squadron tow an F-15 Eagle into a protective aircraft shelter in preparation for Typhoon Man-Yi 12 Jul 07 at Kadena Air Base, Japan. (Source: U.S. Air Force/A1C Kasey Zickmund)

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Organization

Satellite AnalystUSAF

SSgt Kienzel

Satellite AnalystUSAF Civilian

Mr. Todd Brandon

Tech Services TechUSAF CivilianMr. Jim Darlow

Chief, Technical ServicesUSAF Civilian

Mr. Matt Kucas

DirectorUSAF Civilian

Mr. Bob Falvey

Satellite Operations USAF

Capt Kathryn Payne

SATOPS, NCOIC USAF

(M)Sgt Ken Viault

Technical AdvisorUSN Civilian

Mr. Ed Fukada

Satellite AnalystUSAF

SrA Rachel Smith

Satellite AnalystUSAF Civilian

Mr. Dana Uehara

Satellite AnalystUSAF

MSgt Mike Oates

Typhoon Duty OfficerUSAF Civilian

Mr. Steve Barlow

Operations OfficerUSN

LCDR Mike Vancas

Typhoon Duty OfficerUSN

LTJG John Mayers

Typhoon Duty OfficerUSAF Civilian

Mr. Rick Ballucanag

Typhoon Duty OfficerUSAF Civilian

Mr. Aaron Lana

Typhoon Duty OfficerUSN

LT Chris Morris

Typhoon Duty OfficerUSN

LCDR Jeremy Callahan Satellite AnalystUSAF

SSgt Rex Ames

USAF: 14 Personnel--Director, 3 Typhoon Duty Officers (TDO), 2 Technical Services, 8 Satellite AnalystsUSN: 5 Personnel--Technical Advisor, 3 Typhoon Duty Officers (TDO), JTWC Operations Officer

CO, NMFC/JTWCNavy

CAPT Grant Cooper

17th OWS/CCUSAF

Lt Col Kurt Brueske

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JTWC Area of Responsibility

JTWCPearl Harbor, HI

Position/Intensity Fixes

- IR/EIR/Vis Issued every 3 hours -- Position and Intensity 0530Z + every 6 hours -- Position only 0230Z + every 6 hours- MW as imagery is available

PGTW

RJTD

KNES

PHFO

FMEE

NFFN

ABRF

ADRM

APRF

DEMS

NZKL

2008 Satellite FixesBy Agency

73%6%

16%

96 266 69 51 2912645

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Total Satellite Fixes Included in JTWC Satellite Fix Archive = 12,581

9199 744 1951

5%

AMSU

SSMI

MMHS

AMSR

TRMM

SSMIS

WIND

2008 Microwave Fixes By Platform (PGTW)

Total Microwave Fixes = 5,111 Over half of PGTW fixes are now microwave

364 453

284

1716 869 644

781

34%

17%13%7%

9%

15%5%

Real-time best tracking and “re-besting”• Duty TDO (forecaster) is responsible to use all currently available data* to

create and maintain the most accurate best track position and intensity during storm lifecycle

• On-coming TDO is responsible to review pervious shifts best track and makeadjustments with any data that was not available during the previous shift

• Post storm re-best track • Each storm is assigned to a TDO for post storm re-analysis• Satellite operations review all satellite fixes for quality control and all imagery

to ensure all available imagery has been “fixed on”• TDO conducts post storm re-analysis using all available data *• Once complete, the Best Track Officer (BTO) completes a thorough review of

the best track using all available data• JTWC Operations Officer completes a review of the entire storm track• JTWC Technical Advisor completes a thorough review of the best track

• Bottom Line: 4 sets of eyes are on the best track prior to approval/publishing• The tool used is Automated Tropical Cyclone Forecast system (ATCF)

*Data: VIS/IR/MSI from GEO, VIS/IR/MW from Polar, Radar, SCAT, Buoys, Ships, Land Stations, Rawindsondes, Dropsondes

JTWC Best Track Processes

ATCF with best track and fixes displayed(WP152008 Sinlaku)

Zoomed ATCF with best track and fixes displayed

Color indicates fix typeRed=conventionalBlue=microwavePurple=aircraftMaroon=automated/researchBrown=radarYellow=flagged

Shape indicates confidenceSquare = +/- 30nmTriangle = +/- 45nmDiamond = +/- 60nm

6-hourly best track positions labeledwith date/time, speed of movementand current intensity

2-hourly best track positions

Fix positions labeled with date/time, confidence, current intensity, speed of movement Dvorak T-number, agency

Geo-referenced imagery on ATCF – TMI 37GHz

Geo-referenced imagery on ATCF – TMI 37GHz (zoomed)

Geo-referenced imagery on ATCF – TMI 85GHz

Geo-referenced imagery on ATCF – TMI 85GHz zoomed

Geo-referenced imagery on ATCF - Visible

Geo-referenced imagery on ATCF – Visible with ASCAT

"The Joint Typhoon Warning Center Tropical Cyclone Best-Tracks, 1945-2000", Chu, Sampson, et al., Aug 2002

JTWC Historical Best Track Data

• 2002 paper documented effort to resolve discrepancies within the JTWC historical dataset*

• One possible reason for questionable data was that 3 different data bases were used to construct the JTWC best-track historical data set– NCDC database– FNMOC Monterey database– ATCF database; partly developed under contract by Neuman

• Corrections were limited to years for which supporting documentation was found– Data after 1984 considered to be of highest quality

• Dataset contains data from 1945 (WNP), 1971 NIO, 1985 SH

JTWC Archive QC Process

• Visually compared and documented differences between the JTWC Archive and the JTWC Annual Tropical Cyclone Reports

• Checked difference against track or data from other sources– Neuman Hurricane Risk Assessment database– Hong Kong Observatory data

• Made recommendation for changes• Implemented approved changes and posted

comments to document changes on JTWC website

Rules Applied in Making Changes

• Typographical errors corrected• Ensure all cyclones includes a

unique “storm ID”• Starting and ending DTG

together with a name specified for changed data

• TC’s with different names could be combined if data suggested they were same cyclone– 1956, Karen and Lucille

combined to Karen-Lucille

• TC not found in ATCR but in archives, renumbered to 50-79

• Different track times; other than 00, 06, 12 & 18 UTC…not changed but comments added to documentation to highlight

• If unable to refute archives then data kept– e.g. NIO archives indicated

significantly higher TC numbers but nothing in ATCR to refute…data retained.

Excerpts from, “A COMPARISON OF TYPHOON BEST-TRACK DATA IN THE WESTERN NORTH PACIFIC: IRRECONCILABLE DIFFERENCES, M. A. Lander, University of Guam, paper presented at the 2008 AMS 28th Conference on Hurricanes and Tropical Meteorology.

Challenges Rectifying Intensity

The following is a quote from the JTWCAnnual Tropical Cyclone report for2001:

“At 270000Z, JTWC classified thesystem as a typhoon based on naval shipobservations indicating sustained windswithin the small eyewall of 75 knots withgusts to 105 knots.”

In this case, the ship observationscorroborated what one might haveexpected given the MI signature (Fig. 1).

Illustrates that averaging intensities frommultiple centers can be very problematic

Questions?