Research on Landfalling

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14 Νοε 2013 (πριν από 3 χρόνια και 4 μήνες)

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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 disdrometer

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

Aggregation
-
dominant periods
Breakup
-
dominant periods

rain
rain
snow
snow
V
Z
V
Z


Breakup dominant

Reflectivity factor

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


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


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

MIPS

915

Disdrometer

XPR

MAX

VAD & RHI

Plan view

88D

MIPS

MAX

Rainband kinematics and microphysics

QPE

Boundary 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
-
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, V
h

and
TKE profiles; (2) RHI’s normal to
the coast


MIPS

915

Disdrometer

XPR

MAX

EVAD

Plan view

88D

MIPS

MAX

Boundary layer experiment

Stratiform kinematics and microphysics

QPE



P
-
3

Dual Doppler
lobe

Dual Doppler
lobe

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


MIPS

915

Disdrometer

XPR

MAX

RHI

Plan view

88D

MIPS

MAX

Boundary layer transition

Rainband kinematics

QPE

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