Vorticity Structures AccompanyingVorticity Structures AccompanyingEyewall Replacement in Hurricane Rita (2005)Eyewall Replacement in Hurricane Rita (2005)

R.A. Houze, Jr., and B.F. SmullR.A. Houze, Jr., and B.F. SmullDepartment of Atmospheric SciencesDepartment of Atmospheric Sciences

University of WashingtonUniversity of Washington

AMS 28th Conf. on Hurricanes & Tropical MeteorologyAMS 28th Conf. on Hurricanes & Tropical MeteorologyOrlando, Florida - 29 April 2007Orlando, Florida - 29 April 2007

Photo within Rita (CAT 4-->5) on 21 Sept 2005 courtesy M. Black, Photo within Rita (CAT 4-->5) on 21 Sept 2005 courtesy M. Black, NOAA/AOML/HRDNOAA/AOML/HRD

Multi-day Intensity Trends for Hurricane Rita

Period of ELDORA Observations DocumentingConcentric Eyewall Structure on 22 September 2005

Best-track Central Pressure & Max Sustained Surface Winds

22 September 2005 - GOES Visible + P-3 TracksEyewall Replacement Phase

M a toen do ac r ySarymirP

Concentric Eyewall Reflectivity Structure2.0 km MSL

1801-1820 UTC NRL P-3/ELDORA Circumnavigation (Units: dBZ)

Double Wind Maximum - Horizontal Wind Speed2.5 km MSL

1801-1820 UTC NRL P-3/ELDORA Circumnavigation (Units: m/s)

M a toen do ac r ySarymirP

Double Wind Maximum - Horizontal Wind Speed0.5 km MSL

1801-1820 UTC NRL P-3/ELDORA Circumnavigation(Units: m/s)

M a toen do ac r ySarymirP

Patterns of Vertical VorticityAccompanying Eyewall Replacement

Patterns of Vertical VorticityAccompanying Eyewall Replacement

~Axisymmetrized Primary Eyewall vs. High Wavenumber Secondary Eyewall Structures

NW Quadrant80 x 80 km2

SE Quadrant80 x 80 km2

Location of NW & SE Quadrant Analysis Domains( Units: 10-4 s-1)

W E

NW Quadrant

NW Quadrant Vorticity - 1.25 km MSL Contrasting scale/orientation of primary vs. secondary eyewall

Vorticity features

Evidence of vorticity dipoles in Evidence of vorticity dipoles in region of secondary eyewall region of secondary eyewall

formation formation

Evidence of vorticity dipoles in Evidence of vorticity dipoles in region of secondary eyewall region of secondary eyewall

formation formation

( Units: 10-4 s-1)Marks and Houze 1983

WE

Eye Moat

NW QuadrantRadial Section

Radial Section - Reflectivity: Vertically coherent concentric eyewall/moat structure -

Contrasting depth/tilt of primary & secondary eyewall features

(Units: dBZ)

WE

Radial Section - Horizontal Wind Speed Contrasting depth/slope of isotach patterns -

Comparatively shallow, sloped secondary eyewall wind maxima

Eye Moat

NW QuadrantRadial Section

(Units: m/s)

WE

Radial Section - Vertical Vorticity Corresponding contrasts in primary vs. secondary eyewall Tremendous vertical coherence of secondary eyewall dipoles

Eye Moat

NW QuadrantRadial Section

( Units: 10-4 s-1)

WE

Radial Section - Vertical Vorticity& Doppler-Derived Air Motion Vectors

Tendency for & w to be correlated

Eye Moat

NW QuadrantRadial Section

( Units: 10-4 s-1)

Reproducibility of Observed StructuresIn Other Quadrants

Reproducibility of Observed StructuresIn Other Quadrants

Vertical Vorticity - 2.0 km MSLRadial section crosses intense primary eyewall mesovortex &

high wavenumber secondary eyewall features beyond

WSW

ENE

(Units: 10-4 s-1)

Radial Section - Vertical Vorticity

ENEWSW

Eye

SE Quadrant Radial Section

( Units: 10-4 s-1)

Tangential Section Vorticity @ 2.0 km - Evidence of high wavenumber structures

SW

NE

( Units: 10-4 s-1)

Corresponding Tilted VorticityStructures Structures within Secondary Eyewall

NESW

x x x x x

(Units: 10-4 s-1)SE Quadrant Tangential Section

FlowShear

Wind Speed in Secondary Eyewall Near-sfc wind maxima at ~5 km spacing

Structures within elevated (2-5 km) layer tilt downshear

x x x x x

(Units: m/s)SE Quadrant Tangential Section

Shear

NESW

Conclusions

•Unprecedented high-resolution view of concentric eyewall structure & dynamics

•Primary eyewall “triangular” with upright local vorticity maxima

•Secondary eyewall

High wavenumber (~25) wind perturbationsWind max strong but shallow & slopedHigh wavenumber vorticity extrema

Tilt radially outward and tangentially downshearTend to correlate with wPossibly associated with near-surface wind maxima

Thanks for your attention…Thanks for your attention…

21 Sept 2005 - GOES Visible + P-3 Tracks

21 Sept 2005 - LF/WSR-88D CompositeIntense Cat-5 Phase

22 September 2005 - GOES Visible + P-3 TracksEyewall Replacement Phase

23 Sept 2005 - WSR-88D Composite + TracksStrongly-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)

dBZdBZVorticity (Vorticity ())

( Units: 10-4 s-1)

Possible Convective Origins Suggested byAccompanying Precipitation Structures

x x x x x

(Units: dBZ)SE Quadrant Tangential Section

Radial Section - Reflectivity

ENEWSW

Eye Moat

SE Quadrant Radial Section

(Units: dBZ)