1. 1 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Composite Analyses of Tropical Convective Systems Prior to Tropical Cyclogenesis Chip Helms Tropical Lunch 26 April 2013

2. 2 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Cyclone Tracy (1974) Genesis: 12/21 Landfall: 12/24 110 kts (Saffir-Simpson Cat. 3) Image courtesy Wikipedia

3. 3 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Methods for Studying TC Genesis Case Study –Allow for detailed analysis –May not be representative of population Composite Study –Identify prominent features in set of cases –Lose details in compositing process

4. 4 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Example: Non-developing system 8/18/2010 ~14 UTC 8/17/2010 ~13 UTC Longitude [°E] Mid-levels will appear weaker in composite Pressure [hPa] Zonal Cross-sections

5. 5 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Solution: Composite on a Subset Select a subset of cases with similar structure –More homogenous subset provides more detail in composites Create subsets using phase space –Position in phase space indicates current state of important, yet highly variable structures Composite all cases located in a given volume of the phase space –Retain more detail (like case studies) –Representative results (like composite studies)

6. 6 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Data CFSRv2, HURDAT2+INVESTs –Convenient for testing methodology –CFSR: Uniform in time –INVEST files contain a selection bias as not every disturbance triggers an INVEST –INVEST files only available since 2005 Use best track as first guess position –Find 500 hPa and 850 hPa center by minimizing difference between tangential and total winds

7. 7 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Phase Space N = 5817 All HURDAT Systems 2005-2012 ALL INVESTs Work in Progress 500 hPa center position relative to 850 hPa Center

8. 8 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=516, Red=15 INVESTs+Pre-Genesis 2010 No 80% Contour

9. 9 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=107, Red=6 80% Contour Was 16<σ<22 INVESTs+Pre-Genesis 2010

10. 10 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=25, Red=6 Was 16<σ<22 INVESTs+Pre-Genesis 2010

11. 11 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=45, Red=6 Was 16<σ<22 INVESTs+Pre-Genesis 2010

12. 12 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=16, Red=4 Was 16<σ<22 INVESTs+Pre-Genesis 2010

13. 13 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems System Evolution: Sandy (2012) 850 vs 500 hPa Tangential Velocity

14. 14 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Unwrapping TCs

15. 15 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Primary Future Work Create an algorithm to identify pre-genesis systems without relying on best track Test and finalize phase space variables Examine composites –e.g. Dev vs Non-dev System evolution in phase space

16. 16 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Side Project Future Work Create real-time phase space diagrams –Generate a climatology of phase space Genesis Productivity (% dev in each volume) –Apply to forecast times to provide a forecast diagnosis of genesis probability Create real-time unwrapped figures

17. 17 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems END

18. 18 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems EXTRA SLIDES

19. 19 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=516, Red=15 Year: 2010

20. 20 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=107, Red=6 Year: 2010

21. 21 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=25, Red=6 Year: 2010

22. 22 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=45, Red=6 Year: 2010

23. 23 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems N=16, Red=4 Year: 2010

24. 24 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems All HURDAT 2005-2012

25. 25 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems INVEST/Pre-Genesis Systems Max Freq: 41 ~ 2.5%

26. 26 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Tropical Depressions

27. 27 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Tropical Storms

28. 28 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Hurricanes

29. 29 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Post Extra-Tropical Transition

30. 30 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Sandy (2012)

31. 31 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Sandy (2012): 10/18 – 10/21

32. 32 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Sandy (2012): 10/22 – 10/25

33. 33 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Sandy (2012): 10/26 – 10/29

34. 34 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Sandy (2012): 10/30 – 10/31

35. 35 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems REMOVED SLIDES

36. 36 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Theory Simpson et al. (1997) and Ritchie and Holland (1997) Evaporative Cooling Stratiform Latent Heating + PV Anomaly Mergers of PV anomalies add PV while averaging thermal properties New PV Anomaly Out of balance with thermal structure Forced Ascent and Evaporative Cooling Act to cool sub-cloud layer Warm anomaly growth not detailed by theory, but would be accomplished by forced subsidence or increased LHR Forced Convergence ++ Concentration term Stretching term MCS

37. 37 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Pre-Genesis Phase Space N = 5817 All HURDAT Systems 2005-2012 Displacement of 500 hPa center Displacement vs Tilt Direction Displacement vs Shear 500-850 hPa Shear vs 500-850 hPa Vorticity Difference Vorticity vs Divergence ~Bulk Lapse Rate vs Upper Level Moisture Upper-level T’ vs Spec. Hum. 500 hPa V λ vs 850 hPa V λ Stronger Mid Vortex Stronger Low Vortex 850 hPa 500 hPa 500-850 hPa 200-850 hPa

38. 38 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Example: Non-developing system

39. 39 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Cyclone Tracy (1974) Genesis: 12/21 Landfall: 12/24 110 kts (Saffir-Simpson Cat. 3) Image courtesy Wikipedia Image courtesy Clark Evans Genesis: 6/23

40. 40 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Issues with Traditional Composites Mid-level features will appear weaker –High variability in system tilt Vertically-aligned systems tend to be stronger –Composites will favor upright systems

41. 41 26 April 2013 Future WorkResultsMethodologyMotivation Chip HelmsComposite Analyses of Tropical Convective Systems Methodology/Data Locate center at 850 and 500 hPa 1) Maximum V λ (0.5° search grid) 2) Minimum Difference of V λ and V (0.25°) 3) Minimum Difference of V λ and V (0.10°) Datasets: CFSRv2, HURDAT2+INVESTs –Convenient for testing methodology –CFSR: Uniform in time –Complete with all the selection bias caveats of the INVEST files