Transcript 041004Seattle_MesoGrpMtg_RAINEXproposal_Houze.ppt

Observational and Modeling Study of Hurricane
Rainbands and Intensity Changes
aka
Rainband and Intensity Change Experiment
“RAINEX”
Shuyi S. Chen and Robert A. Houze, Jr.
Four characteristic tropical cyclone
rainband/eyewall structures
Working hypothesis, based on
recent research:
In the convective
rainband region
outside of the
hurricane inner core,
convectively induced
potential vorticity may
be “axisymmetrized”
by high wave number
Rossby waves.
Specific questions
1) How do PV maxima associated with
rainbands organize (axisymmetrize) into the
primary eyewall?
2) How do PV maxima associated with
rainbands outside the primary eyewall
interact with the eyewall?
3) How do PV maxima associated with
rainbands outside the primary eyewall
axisymmetrize into a secondary eyewall
4) How do the secondary and primary eyewall
interact with each other
Objectives

Use a/c to examine the dynamic and
thermodynamic structures of
hurricane outer rainband regions
where the positive potential vorticity
associated with deep convective
cores are located

Use model to investigate the
interactions of the rainbands and
primary hurricane vortex circulation
and their role in hurricane intensity
change.
Approach:
Use a/c to observe both eyewall and
rainband vorticity structures
simultaneously
Seek match between model and a/c
observed structures at an instant of
time, in both eyewall and rainband
Use model to determine how the
vorticity features evolve and storm
intensity changes
Hurricane Floyd (1999)
12 Sep 2230-2300 UTC
13 Sep 2300-2330 UTC
RAINEX A/C Plan
Isabel 2003
End
Courtesy, Hugh Willoughby
Approach
For structures:
Use airborne dual-Doppler radar
For interactions:
Use University of Miami coupled
model (MM5-WW3-HYCOM)