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

MIPS Components

915 MHz profiler

Electric Field Mill

12-channel Microwave Profiling Radiometer

Ceilometer

2 kHz Doppler sodar

Surface instr.Satellite comm.

Not shown: 2 raingages and disdrometer

X

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.

Miscellaneous surface instruments

Parsivel disdrometerElec. 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 bandAggregation occurs most of the time

Aggregation-dominant periods Breakup-dominant periods

rainrain

snowsnow

VZ

VZ=γ Breakup dominant

Reflectivity factor

€

γ=ZsnowVsnowZrainVrain

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 plan

MAX sampling• VAD to high elevation

– Vertical motion– Hydrometeor fall speeds– Profiling of both mean

wind and TKE

• Sector scans

• RHIQuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

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

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 lobee) P-3 Doppler support, in situ

microphysics, dropsondes

MIPS915

Disdrometer

XPR MAXVAD & RHI

Plan view88D

MIPS MAX

Rainband kinematics and microphysicsQPEBoundary layer (shear along the coast)

15 km

30-40 km

P-3

Dual Doppler lobe

Dual Doppler lobe

Locate within 30-40 km of 88D when possible

MIPS and MAX co-locateda) XPR will provide high resolution

turbulent fluctuationsb) 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

MIPS915

Disdrometer

XPR MAX

EVAD

Plan view88D

MIPS MAX

Boundary layer experiment Stratiform kinematics and microphysicsQPE

P-3

Dual Doppler lobe

Dual Doppler lobe

MIPS and MAX separated by 5-10 kma) XPR will provide high resolution

vertical profiles of Doppler spectrab) 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

MIPS915

Disdrometer

XPR MAXRHI

Plan view88D

MIPSMAX

Boundary layer transitionRainband kinematicsQPE

30-40 km

P-3

Dual Doppler lobe

Dual Doppler lobe

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