Convection in the Genesis Phase of Ophelia (2005)

Wen-Chau Lee* Michael Bell* Robert Houze#

*NCAR/EOL#University of Washington

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

Existing Ideas on Upscale Effects of Clouds in TC Genesis

Hendricks et al. (2004) Convective

Bister and Emanuel (1997) Stratiform

Richie et al. (2003) Multiple stratiform

Other??

Ophelia’s history

6 Sep RAINEX flight

~200 km

6 Sep RAINEX

flight

Satellite IR Coastal radar

12 hours later

24 hours later

~200 km

Satellite IR Coastal radar

ELDORA reflectivity

2108

2123

2136

15 km

30 km

2 km

2108 UTC

1.6 km 6 km

14 km 6.0 km

dBZ, wind dBZ, wind

dBZ, wind , perturbation wind

2123 UTC

1.6 km 6 km

14 km 6.0 km

dBZ, wind dBZ, wind

dBZ, wind , perturbation wind

2136 UTC

1.6 km 6 km

14 km 6.0 km

dBZ, wind dBZ, wind

dBZ, wind , perturbation wind

Pressure and Buoyancy Retrieval

8 km2108 UTC

Color : ρw Contour :

∂ρw∂z

Structure in the Stratiform Region

Reflectivity & Wind Vorticity & perturbation wind

Circulation

Circulation : Γ = dA

A∫∫Average vorticity profile

Summary• Deep convective updaft of an MCS is important in

genesis stage of Ophelia• Convective updraft generates positive PV at low

and midlevels • Convective updraft is deep (~16 km), wide (~20

km), and strong (up to 30 m/s)• T’ and p’ both contribute to updraft• Downdrafts don’t play an obvious role• These observations don’t exactly fit the previous

notions of convection related to genesis…

Thank You

CFAD of Mass Transport and Vertical Velocity in Ophelia

Mass transport in the convective domain. Left column shows mass transport normalized to the peak positive value for the three convective analysis legs. Black lines indicate upward transport, dashed dark gray line denotes downward transport, and light gray dash-dot line is net transport. Right column shows contour frequency by altitude (CFAD) diagrams with mass weighted vertical velocity in 106kg s-1 contours, with 30x106kg s-1 contour highlighted. Data is binned in 1 m s-1vertical velocity increments.

Stratiform Region

Convective Region

Radar Loop from KMLB

QuickTime™ and aH.264 decompressor

are needed to see this picture.

Can synthesize the 3-D wind fields by flying by a phenomenon.

~300 m

Nyquist Velocity up to 100 m/s

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