Transcript 080429Orlando_TropConf_RAINEX_Rita_V20_HouzeSmull.ppt

Vorticity Structures Accompanying
Eyewall Replacement in Hurricane Rita (2005)
R.A. Houze, Jr., and B.F. Smull
Department of Atmospheric Sciences
University of Washington
AMS 28th Conf. on Hurricanes & Tropical Meteorology
Orlando, Florida - 29 April 2007
Photo within Rita (CAT 4-->5) on 21 Sept 2005 courtesy M. Black,
NOAA/AOML/HRD
Multi-day Intensity Trends for Hurricane Rita
Period of ELDORA Observations Documenting
Concentric Eyewall Structure on 22 September 2005
Best-track Central Pressure & Max Sustained Surface Winds
22 September 2005 - GOES Visible + P-3 Tracks
Eyewall Replacement Phase
Concentric Eyewall Reflectivity Structure
2.0 km MSL
1801-1820 UTC NRL P-3/ELDORA Circumnavigation
(Units: dBZ)
Double Wind Maximum - Horizontal Wind Speed
2.5 km MSL
1801-1820 UTC NRL P-3/ELDORA Circumnavigation
(Units: m/s)
Double Wind Maximum - Horizontal Wind Speed
0.5 km MSL
1801-1820 UTC NRL P-3/ELDORA Circumnavigation
(Units: m/s)
Patterns of Vertical Vorticity
Accompanying Eyewall Replacement
~Axisymmetrized Primary Eyewall z vs.
High Wavenumber Secondary Eyewall Structures
Location of NW & SE Quadrant Analysis Domains
(z Units: 10-4 s-1)
NW Quadrant
80 x 80 km2
SE Quadrant
80 x 80 km2
NW Quadrant Vorticity - 1.25 km MSL
Contrasting scale/orientation of primary vs. secondary eyewall
Vorticity features
(z Units: 10-4 s-1)
NW Quadrant
Marks and Houze 1983
Evidence of vorticity dipoles in
region of secondary eyewall
formation
W
E
Radial Section - Reflectivity:
Vertically coherent concentric eyewall/moat structure Contrasting depth/tilt of primary & secondary eyewall features
(Units: dBZ)
NW Quadrant
Radial Section
Eye
E
Moat
W
Radial Section - Horizontal Wind Speed
Contrasting depth/slope of isotach patterns Comparatively shallow, sloped secondary eyewall wind maxima
(Units: m/s)
NW Quadrant
Radial Section
Eye
E
Moat
W
Radial Section - Vertical Vorticity
Corresponding contrasts in primary vs. secondary eyewall z
Tremendous vertical coherence of secondary eyewall dipoles
(z Units: 10-4 s-1)
NW Quadrant
Radial Section
Eye
E
Moat
W
Radial Section - Vertical Vorticity
& Doppler-Derived Air Motion Vectors
Tendency for z & w to be correlated
(z Units: 10-4 s-1)
NW Quadrant
Radial Section
Eye
E
Moat
W
Reproducibility of Observed Structures
In Other Quadrants
Vertical Vorticity - 2.0 km MSL
Radial section crosses intense primary eyewall mesovortex &
high wavenumber secondary eyewall features beyond
(Units: 10-4 s-1)
Radial Section - Vertical Vorticity
SE Quadrant
Radial Section
(z Units: 10-4 s-1)
Eye
WSW
ENE
Tangential Section
Vorticity @ 2.0 km - Evidence of high wavenumber structures
(z Units: 10-4 s-1)
Corresponding Tilted Vorticity
Structures Structures within Secondary Eyewall
SE Quadrant
Tangential Section
(Units: 10-4 s-1)
Shear
Flow
x
SW
x
x
x
x
NE
Wind Speed in Secondary Eyewall
Near-sfc wind maxima at ~5 km spacing
Structures within elevated (2-5 km) layer tilt downshear
SE Quadrant
Tangential Section
(Units: m/s)
Shear
x
SW
x
x
x
x
NE
Conclusions
•Unprecedented high-resolution view of concentric
eyewall structure & dynamics
•Primary eyewall “triangular” with upright local vorticity
maxima
•Secondary eyewall
High wavenumber (~25) wind perturbations
Wind max strong but shallow & sloped
High wavenumber vorticity extrema
Tilt radially outward and tangentially downshear
Tend to correlate with w
Possibly associated with near-surface wind
maxima
Thanks for your attention…
21 Sept 2005 - GOES Visible + P-3 Tracks
21 Sept 2005 - LF/WSR-88D Composite
Intense Cat-5 Phase
22 September 2005 - GOES Visible + P-3 Tracks
Eyewall Replacement Phase
23 Sept 2005 - WSR-88D Composite + Tracks
Strongly-sheared Landfall Phase
Mesovortex along Primary Eyewall of Rita
Associated Reflectivity @ 0.5 km MSL
(Units: dBZ)
Mesovortex along Primary Eyewall of Rita
Wind Speed @ 0.5 km MSL
(Units: m/s)
Mesovortex Along Primary Eyewall of Rita
Vertical Vorticity @ 0.5 km MSL
(Units: 10-4 s-1)
3-D Exploration of Mesovortex Structure
Map @ 0.5 km MSL & Radial Cross Section)
(z Units: 10-4 s-1)
dBZ (z)
Vorticity
Possible Convective Origins Suggested by
Accompanying Precipitation Structures
SE Quadrant
Tangential Section
x
(Units: dBZ)
x
x
x
x
Radial Section - Reflectivity
SE Quadrant
Radial Section
Eye
WSW
(Units: dBZ)
Moat
ENE