Research on Landfalling Hurricanes Utilizing Ground-Based Mobile Research Platforms

1. Research on Landfalling Hurricanes Utilizing Ground-Based Mobile Research Platforms Kevin Knupp, Dan Cecil, Walt Petersen, and Larry Carey University of Alabama in Huntsville

2. Mobile facilities • MIPS: Mobile Integrated Profiling System (UAH): • 915 MHz wind profiler (915) • X-band Profiling Radar (XPR)* • 12-channel microwave profiling radiometer • Ceilometer • Parsivel laser disdrometer • Surface instrumentation (electric field mill is an option) • MAX: Mobile Alabama X-Band dual polarization radar (UAH)* • Portable Lightning Mapping Array (NASA)* • Instrumented automobile (standard meteorological variables) * under development, expected prior to hurricane season

3. Surface instr. MIPS Components Satellite comm. X 2 kHz Doppler sodar Ceilometer 915 MHz profiler Electric Field Mill 12-channel Microwave Profiling Radiometer Not shown: 2 raingages and disdrometer

4. A vertically-pointing X-band radar (fabrication in progress) will replace the sodar

5. Mobile Alabma X-band (MAX) dual polarization radar (Joint effort between UAH and Baron Services) Initial tests conducted on 3/4/08 were successful! Now in the process of calibration.

6. Miscellaneous surface instruments Elec. Field Mill Parsivel disdrometer

7. Scientific topics • Kinematics, microphysics, and thermodynamics of rain bands and stratiform rain areas • Mesoscale updrafts and downdrafts within stratiform • Convective transports • Hurricane-spawned tornadoes: • Kinematics of intense rainbands • Mini-supercell kinematics • Boundary layer characteristics • Mean wind profiles • TKE profiles • BL transition: water to land; land to water • Shear/convergence along the coast (differential drag) • QPE • Miscellaneous targets of opportunity

8. Mesoscale motions within stratiform areas • Example: • Hurricane Ivan (2004) • Relationship to cooling by evaporation (mesoscale downdrafts) and associated intensity change around the time of landfall • Stratiform precipitation is the majority within the TC

9. Vertical Velocity (contoured; e plotted below the figure) Outer stratiform and rainbands core

10. 2 km TREC analysis (KMOB) ground-relative winds: 2230 UTC

11. Microphysics of of an intense stratiform rainband • Tropical Storm Gabrielle (2001) • EVAD analysis of SMART-R • Analysis of 915 vertical beam spectra • Bright-band physics (example follows) • DSD profiles and their variability

12. Aggregation-dominant periods Breakup-dominant periods Detailed look at the bright bandAggregation occurs most of the time Reflectivity factor Breakup dominant

13. Boundary layer transition • Tropical Storm Gabrielle (2001) • Combined Doppler radar (SMART-R) and 915 analysis • On-shore flow vs. off-shore flow

14. 915 MHz profiler moments Enhanced spectrum width (turbulence) marks the BL

15. Details of the wind profiles for onshore flow • Wind profiles have a similar shape. • A combination of spatial (mesoscale) and temporal variability may be present. • A side experiment: compare dropsonde wind profile with mean wind profiler profile and wind components within an RHI vertical plan

16. MAX sampling Doppler radars and serve as very powerful profiling systems • VAD to high elevation • Vertical motion • Hydrometeor fall speeds • Profiling of both mean wind and TKE • Sector scans • RHI

17. Generic experimental designs • A specific design will satisfy more than one scientific objective • Two types: • MIPS and MAX co-located • MIPS and MAX separated

18. Rainband kinematics and microphysics QPE Boundary layer (shear along the coast) Locate within 30-40 km of 88D when possible VAD & RHI Disdrometer 915 MAX XPR MIPS XPR will provide high resolution vertical profiles of Doppler spectra 915 will scan in normal profiling mode (wind profiles) MAX: RHI scans over MIPS; VAD scans for dual Doppler and profiing MIPS within dual Doppler lobe P-3 Doppler support, in situ microphysics, dropsondes Plan view 88D Dual Doppler lobe Dual Doppler lobe 30-40 km 15 km MAX MIPS P-3

19. Boundary layer experiment Stratiform kinematics and microphysics QPE EVAD Disdrometer 915 MAX XPR MIPS Plan view MIPS and MAX co-located XPR will provide high resolution turbulent fluctuations 915 will scan in normal profiling mode (wind profiles) MAX will conduct: (1) VAD scans to high elevation to get W, DIV, Vh and TKE profiles; (2) RHI’s normal to the coast 88D Dual Doppler lobe Dual Doppler lobe MAX MIPS P-3

20. Boundary layer transition Rainband kinematics QPE RHI Disdrometer 915 MAX XPR MIPS Plan view MIPS and MAX separated by 5-10 km XPR will provide high resolution vertical profiles of Doppler spectra 915 will scan in normal profiling mode (wind profiles) MAX will run in profiling mode and acquire RHI scans over MIPS and opposite MIPS 88D Dual Doppler lobe 30-40 km Dual Doppler lobe MIPS MAX P-3

21. Other considerations • Coordination with other groups • Other radars (DOW, SMART-R) • Surface measurements (USA network, FMCP and TTU deployments) • Specific design depends on locations of good sites and intensity of the tropical cyclone.

22. Summary • Mobile ground-based instruments will provide additional information on the physical processes associated with landfalling TC’s • Perhaps the best targets are weaker hurricanes (<Cat 2) and tropical storms • The measurements will also likely enhances understanding of TC physical processes over the ocean: • Microphysical processes • Mesoscale motions within the stratiform regions • Rainband kinematics • Eye/eyewall dynamics • Boundary layer characteristics