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Best Track Parameters

Best Track Parameters. IBTrACS Perspective. 2nd IBTrACS Workshop. 11-13 April 2011. 1. IBTrACS Workshop recommendations. The IBTrACS team should… Document BT procedures, Work with agencies Through a survey Provide all parameters as provided by original agency in IBTrACS

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Best Track Parameters

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  1. Best Track Parameters • IBTrACS Perspective 2nd IBTrACS Workshop 11-13 April 2011 1

  2. IBTrACS Workshop recommendations • The IBTrACS team should… • Document BT procedures, • Work with agencies • Through a survey • Provide all parameters as provided by original agency in IBTrACS • Distribute official and unofficial datasets of other TC related data • Archive all ancillary data • Get involved with the IWTC 2nd IBTrACS Workshop 11-13 April 2011

  3. IBTrACS Workshop recommendations • Best tracking agencies should … • Report more parameters and use WMO format • Document current and historic BT practices • Standardize definitions of winds and wind conversions • Rescue and archive documents relevant to BT data • “Best track” throughout life cycle (through ET) • Encourage best track data discussions at IWTC 2nd IBTrACS Workshop 11-13 April 2011

  4. WMO Format • What data are important to keep for future generations? 2nd IBTrACS Workshop 11-13 April 2011 4

  5. Parameter summary • From allagencies • Time, Latitude, longitude • Wind & Pressure • Cyclone type • From someagencies • Wind radii (5) • Radius of Maximum Winds (4) • Radius of outermost closed isobar (3) • Pressure of outermost closed isobar (2) • Dvorak Parameters: T-number and CI (2) 2nd IBTrACS Workshop 11-13 April 2011

  6. Cyclone Type • Tropical disturbance (no closed isobars) • < 34 kt winds (< 17 m/s winds) and at least one closed isobar • 34-63 kt (17-32 m/s) • > 63 kt (> 32 m/s) • extratropical • dissipating • subtropical cyclone (nonfrontal, low pressure system that comprises initially baroclinic circulation developing over subtropical water) • overland • unknown 2nd IBTrACS Workshop 11-13 April 2011

  7. Position • latitude/longitude • date/time • position confidence • Confidence in center position: radius of smallest circle within which the center may be located by analysis • good (<30 nm; <55 km) • fair (30 - 60 nm; 55 -110 km) • poor (>60 nm; >110 km) 2nd IBTrACS Workshop 11-13 April 2011

  8. Dvorak Estimates • T-number/CI-number • Is this intensity estimate the most objective value each agency has in common? • Is the Objective Dvorak the best climate data record we are currently generating? 2nd IBTrACS Workshop 11-13 April 2011

  9. Pressure • Minimum Central Pressure • Pressure quality • aircraft or dropsonde • marine observation • land surface observation • Dvorak • other 2nd IBTrACS Workshop 11-13 April 2011

  10. Wind • Maximum average wind speed • time interval for wind speed average • Maximum gust • gust period (s) • Wind quality • aircraft or dropsonde • marine observation • land surface observation • Dvorak • other ? 2nd IBTrACS Workshop 11-13 April 2011

  11. Wind Radii • Radius of maximum wind (RMW) • RMW Quality • Aircraft observation • Radar with well-defined eye • Satellite with well-defined eye • Radar or satellite, poorly defined eye • Other estimate 2nd IBTrACS Workshop 11-13 April 2011

  12. Radius by sector • Wind threshold (choose only 2 in WMO) • 34 kt? 50 kt? 64 kt? • units for speed & distance? • Quality code • Aircraft observation • Radar with well-defined eye • Satellite with well-defined eye • Radar or satellite, poorly defined eye • Other estimate 2nd IBTrACS Workshop 11-13 April 2011

  13. 2nd IBTrACS Workshop 11-13 April 2011

  14. What sectors? • 0° - 90° • 90° - 180° • 180° - 270° • 270° - 360° • 315° - 45° • 45° - 135° • 135° - 225° • 225° - 315° 2nd IBTrACS Workshop 11-13 April 2011

  15. Parameters in use WMO Parameters 2nd IBTrACS Workshop 11-13 April 2011

  16. Mean position Mean intensity Original positions & intensity Original positions & intensity Other parameters as available WMO position In prep. WMO intensity Mean position Mean intensity Mean position JAOT Mean intensity Kruk et al., 2010 Mean position BAMS Mean intensity Knapp el al., 2010 Ver. 1 Ver. 3 Ver. 2 IBTrACS Data Formats 1 intensity per report • netCDF • CSV • WMO • HURDAT • ATCF • cXML • GIS shapefile • Multiple intensities possible 2nd IBTrACS Workshop 11-13 April 2011

  17. Forecaster/ Analyst Time Available Data User needs A balancing act… 2nd IBTrACS Workshop 11-13 April 2011

  18. User needs… • IBTrACS requested users to identify their needs • Results… • Storm size information • RMW, Wind radii, ROCI • Higher temporal resolution • More the just 6 hourly • Landfall, maximum intensity, etc. • At least cyclone type 2nd IBTrACS Workshop 11-13 April 2011

  19. Best Track Parameter Questions: • Based on the WMO best track format parameters, which parameter could be most easily added to the BT record from your agency? • What next parameter would be of the most use for users? (researchers, etc.) • What would it take to add: • Confidence flags? • Quality indicators? 2nd IBTrACS Workshop 11-13 April 2011

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