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I nternational B est Tr ack A rchive for C limate S tewardship

Best Track Data and Synoptic Studies: What is a tropical cyclone? Carl J. Schreck, III CICS-NC, NCSU and NCDC. I nternational B est Tr ack A rchive for C limate S tewardship. Weather vs. Climate. Climate studies: Basin-centric How many storms have there been? How strong were they?

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I nternational B est Tr ack A rchive for C limate S tewardship

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  1. Best Track Data and Synoptic Studies: What is a tropical cyclone? Carl J. Schreck, III CICS-NC, NCSU and NCDC International Best Track Archive for Climate Stewardship

  2. Weather vs. Climate • Climate studies: Basin-centric • How many storms have there been? • How strong were they? • Is there a trend? • Synoptic Studies: Storm-centric • When did it form or dissipate? • When did it strengthen or weaken? • Was it tropical, subtropical or extratropical?

  3. When does a tropical cyclone become a tropical cyclone? • Tropical Depressions: • Capable of intensifying through internal feedbacks • Not always best tracked • Some best track datasets include pre-depression disturbances • Named Storms: • More consistently best tracked • When does it become named? • 30 kts? 35 kts? 1-min winds? 10-min winds?

  4. Rammasun & Chataan • Numerous scales interacting within the MJO’s convective envelope Unfiltered TRMM rainfall (shading)

  5. Rammasun & Chataan • Kelvin wave provided: • Convection • Westerlies • Cyclonic PV • Could this case be identified objectively? Unfiltered TRMM rainfall (shading) Kelvin-filtered rainfall (contours)

  6. Rammasun & Chataan • First recorded position varies by up to 60 h and 300 km between agencies Unfiltered TRMM rainfall (shading) Kelvin-filtered rainfall (contours)

  7. When did they form?

  8. When did they form?

  9. Distribution of Intensities (1979-2009) 37% zero or missing JTWC JMA

  10. FullIBTrACS(1979-2009)

  11. When does a tropical cyclone stop being a tropical cyclone? Unique Tracks

  12. Unique Tracks (≥30 kts)

  13. Summary • The more data, the better • Pre-genesis • Post-extratropical transition • Need documentation on what is and is not included • Seems like 30 kts is the most consistent threshold for cyclogenesis • Need Storm Type

  14. Cyclone Type • 01= tropics; disturbance (no closed isobars) • 02= <34 knot winds, <17m/s winds and at least one closed isobar • 03= 34-63 knots, 17-32m/s • 04= >63 knots, >32m/s • 05= extratropical • 06= dissipating • 07= subtropical cyclone • 08= overland • 09= unknown • TS= tropical in nature • ET= extratropical • SS= subtropical storm • MX= conflicting reports • NR= not reported WMO Format Current IBTrACS

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