Airborne Radar Observations of Atlantic Tropical Cyclones

1. Airborne Radar Observations of Atlantic Tropical Cyclones Jennifer DeHart 09.21.11

2. Motivation Andrew: $26.5 billion in damage Katrina: 1200 deaths, $108 billion in damage Adam Willemssen National Hurricane Center

3. Forecast error National Hurricane Center

4. Basic Axisymmetric Eyewall Structure Willoughby 1998

5. Eyewall Asymmetries • Potential Causes • Gradient of f • Storm Track • Environmental Moisture Distribution • Vertical Shear Black et al., 2002 Braun et al., 2006 Chen et al., 2006

6. UL DL UR DR Black et al., 2002 modified by Houze 2009

7. Quantifying Vertical Structure • Deanna Hence studied satellite data from TRMM • Snapshots of radar reflectivity • 10+ years of data • Contoured by Frequency Altitude Diagrams (CFADs)

8. Height (km) Reflectivity (dBZ) Hence and Houze 2011

9. Hence and Houze 2011

10. Statistics to Dynamics • Can we relate vertical structure of reflectivity to dynamics? • Aircraft Observations • 3-D reflectivity, thermodynamics, winds

11. GRIP • August 15th – September 30th, 2010 • Aircraft: DC-8, Global Hawk, WB-57 • Data collected: Radar, dropsondes • APR-2: Ka and Ku band

12. RAINEX • September – August 2005 • Hurricanes sampled • Katrina, Ophelia, Rita • P3 Tail and ELDORA Radars • X band

13. Hurricane Katrina – 8.28.05 • Data from 17-23Z • Rapidly Intensified to Category 5 by 12Z • Peak Intensity of 150 kt at 18Z • Weakened, made landfall as Category 3 at 11Z on 8.29.05 • Shear shifted from SE toESE with constant speedof 4 m/s. National Hurricane Center

15. Shear

16. Conclusions So Far: Katrina’s Structure vs. TRMM • Consistent with statistics • Eyewall echoes stronger and taller downshear • Low-level DL echoes have more variability than DR • Upshear quadrants dominated by weak echoes at high altitudes • Differences related to intensity/shear • Modal distributions upshear on high end

17. Future Plans • Extend shear analysis to other fields • Thermodynamics, vertical wind shear • Dropsondes • 3D Wind • Doppler analysis of radar data • Subdivide storm into eyewalls, concentric eyewalls, rainbands • Focus on Katrina (2005), Rita (2005) and Earl (2010)

18. GRIP Flight Plan

19. Doppler Analysis NOAA HRD

20. Future Plans • Extend shear analysis to other fields • Subdivide storm into eyewalls, concentric eyewalls, rainbands • Focus on Katrina (2005), Rita (2005) and Earl (2010) • All major storms

21. Thank you! • Dr. Houze • Stacy Brodzik • Housemates/Grads10+Kirsten • Mesoscale Group Felipe

22. References • Black, M. L., J. F. Gamache, F. D. Marks, C. E. Samsury, and H. E. Willoughby, 2002: Eastern Pacific Hurricanes Jimenaof 1991 and Olivia of 1994: The effect of vertical shear on structure and intensity. Mon. Wea. Rev., 130, 2291–2312. • Braun, S. A., M. T. Montgomery, and Z. Pu, 2006: High-resolution simulation of Hurricane Bonnie (1998). Part I: The organization of eyewallvertical motion. J. Atmos. Sci., 63, 19–42. • Chen, S. Y. S., J. A. Knaff, and F. D. Marks, 2006: Effects of vertical wind shear and storm motion on tropical cyclone rainfall asymmetries deduced from TRMM. Mon. Wea. Rev., 134, 3190–3208. • Corbosiero, K. L., and J. Molinari, 2002: The effects of vertical wind shear on the distribution of convection in tropical cyclones. Mon. Wea. Rev., 130, 2110–2123. • Houze R. A., 2010: Clouds in tropical cyclones. Mon. Wea. Rev., 138, 293–344.

23. Effects of Shear • Azimuthal distribution of vertical motion, lightning, reflectivity and rainfall • Asymmetries maximized downshear • Inner core: left of shear • Outer bands: right of shear • Vortex tilted Braun et al., 2006 Chen et al., 2006 Corbosiero and Molinari 2002 Corbosiero and Molinari 2003

24. Mesovortices • Occur along inner edge of eyewall reflectivity • Instability of axisymmetric annulus of vorticity Braun et al., 2006

25. Braun et al., 2006