Convective-scale variations in the inner-core rainbands of

tropical cyclones

Anthony C. Didlake, Jr. and Robert A. Houze, Jr.30th Conference on Hurricanes and Tropical Meteorology

April 17, 2012

Houze 2010

NCAR ELDORA radar

9/21/2005 1845-1927 Z2 km reflectivity

C o n v e c t i v e

S t r a t i f o r m

dBZ

Hurricane Rita

Method of analysis Divide into “inner” and “outer” regions Classify pixels as “convective” or “stratiform” Take radial cross sections across convective regions

Inner

Outer

Method of analysis

Inner

Outer

Divide into “inner” and “outer” regions Classify pixels as “convective” or “stratiform” Take radial cross sections across convective regions

inner region outer region v (m/s)

Tangential wind (m/s) – Shaded contoursReflectivity (dBZ) – Contour linesSecondary circulation – Vectors

Composite cross sections

eye

inner region outer region

Tangential wind

Radial wind

v (m/s)

u (m/s)Hence and Houze 2008

inner region outer region

Tangential wind

Radial wind

v (m/s)

u (m/s)

Vertical velocity (m/s)

solid – innerdashed – outer

CAPE as a function of radius

Bogner et al. 2000

down uptotal

Alti

tude

(km

)

inner region outer regionTangential momentum tendency

blue – radial advectionred – vertical advectiongreen – Coriolis term

acceleration (m s-2) acceleration (m s-2)

Alti

tude

(km

)

Total tendencyTangential momentum tendency

acceleration (m s-2)

D red – inner black – outer

acceleration (m s-2)

Alti

tude

(km

)

9/21/2005 2010 Z

9/22/2005 1800 Z

Didlake and Houze 2012

Didlake and Houze 2011

Rainband convective cells

Secondary eyewall

Critical zone for secondary eyewall formation Strong winds and low

CAPE Confinement of jet Amplification via WISHE

feedback Inner edge subsidence

Didlake and Houze 2012

Didlake and Houze 2011

Rainband convective cells

Secondary eyewall

Conclusions Kinematic structure varies with radius Tangential jet depends on radial and

vertical advectionInner cell jets constrained to low levelsOuter cell jets occur within large range of

altitudes Convective cells can reach critical zone of

secondary eyewall formation

Acknowledgments Michael Bell Wen-Chau Lee Stacy Brodzik NDSEG Fellowship Program NSF grant ATM-0743180