Research on Landfalling Hurricanes Utilizing Ground Based Mobile

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

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

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

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

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.

Parsivel disdrometer Miscellaneous surface instruments Elec. Field Mill

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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