1. Shuyi S. Chen Joseph Tenerelli Rosenstiel School of Marine and Atmospheric Science University of Miami Effects of Environmental Flow and Initial Vortex on Eyewall Replacements in Tropical Cyclones 2004 Western Pacific Geophysics Meeting, Honolulu, 16-20 August

2. NOAA/HRD&AOC Radar Composites in Hurricane Isabel (2003) 9/12/03 1700 UTC9/12/03 2000 UTC9/13/03 1600 UTC 9/13/03 1800 UTC9/14/03 1600 UTC9/14/03 2000 UTC

3. NOAA/HRD&AOC Radar Composites in Hurricane Lili (2002) 10/02 0600 10/02 0900 10/02 1800 10/02 1900 10/02 1700 10/03 1500

4. Hurricane Floyd (1999) MM5

5. Hurricane Floyd (1999)

7. TRMM TMI

9. Isabel (2003) Floyd (1999)

10. Isabel (2003) Floyd (1999)

12. What are the impacts of initial vortex size on intensity, inner core structure and eyewall cycles of simulated tropical cyclones?

18. Model Configuration Eliminate land; set terrain height to zero. Set SST to constant 303 K. Turn off shortwave radiation. Retain longwave radiation. Fix Coriolis force at 5x10 -5 s -1. Eliminate curvature terms. Set the map scale factor to unity.

22. Surface Rain Rate

23. Wind at 3 km Level

25. Moist Potential Vorticity

26. Radial Wind

27. What is the influence of environmental flow on the inner core structure and eyewall cycles of simulated tropical cyclones? Moisture Vertical wind shear

28. Mean RH Profiles Derek and Chen (2004): NOAA/G-IV GPS dropsondes (49 flights and 1002 dropsondes, mostly taken in the TC environment outside of 300 km radius from TC centers)

29. Track Chen&Desflots (UM/RSMAS)

30. Intensity (a) pressure(b) wind speed Chen&Desflots (UM/RSMAS)

33. Eyewall Evolution in Lili (2002) pressure

34. Shear Analysis in Lili (2002) SLP : 943.9mb SHEAR:0.55m/s SLP : 943.9mb SHEAR:2.8m/s SLP : 944.4mb SHEAR:4.4m/s SLP : 948.9mb SHEAR:7m/s SLP : 953.1mb SHEAR:9m/s SLP : 955.1mb SHEAR:9.2m/s

35. Rainfall Moist simulationControl runDry simulation

36. Conclusions Initial vortex structure seems to have a significant influence on the evolution of TC inner core and eyewall replacements. Minimum SLP is only weakly dependent upon initial vortex size, whereas maximum wind speed exhibits some variability between runs, with higher speeds for smaller vortices. Influence of environmental moisture distribution and vertical wind shear on eyewall cycles is complex and storm-dependent. Questions: Are we any better in predicting TC intensity changes than a decade ago? Yes, ……but, …….