AMS 28th Conf. on Hurricanes & Tropical Meteorology Orlando, Florida - 29 April 2007 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 Meteorology Orlando, 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 IRCoastal radar 12 hours later 24 hours later
~200 km Satellite IRCoastal radar
ELDORA reflectivity km 30 km 2 km
2108 UTC 1.6 km6 km 14 km6.0 km dBZ, wind , perturbation wind
2123 UTC 1.6 km6 km 14 km6.0 km dBZ, wind , perturbation wind
2136 UTC 1.6 km6 km 14 km6.0 km dBZ, wind , perturbation wind
Pressure and Buoyancy Retrieval 8 km 2108 UTC
Structure in the Stratiform Region Reflectivity & WindVorticity & perturbation wind
Circulation 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 10 6 kg s -1 contours, with 30x10 6 kg s -1 contour highlighted. Data is binned in 1 m s -1 vertical velocity increments. Stratiform Region Convective Region
Radar Loop from KMLB
Can synthesize the 3-D wind fields by flying by a phenomenon. ~300 m Nyquist Velocity up to 100 m/s
3-D Variational Formulation (Gamache 1997):