27th Conference on Hurricanes and Tropical Meteorology


The MCS life cycle: prototype or building block of larger-scale waves?

Brian Mapes, Univ. of Miami/RSMAS, Miami, FL; and S. N. Tulich

The tilted structure of large-scale tropical waves is remarkably similar to that of individual Mesoscale Convective Systems (MCSs). This structure is encapsulated crisply and objectively via lagged regressions of time-height data against a surface rainfall time series. Shallow convection grows deeper over time, with a distinct midlevel divergence maximum at the congestus phase. Deep convection transitions to stratiform precipitation, with characteristic vertical-dipole heating and vertical motion profiles.

How can the recurrence of similar structure at different scales be explained? Synthetic-data exercises illustrate that simple aliasing of small scales onto large (the Building Block hypothesis) is not enough. Rather, large-scale waves apparently modulate convective cloud processes in ways that are similar to how an MCS is organized (the Prototype concept). This raises questions and hypotheses about convective modulation by larger scales generally, and about the wave-like nature of MCSs themselves.


Session 8D, Tropical Convection II
Wednesday, 26 April 2006, 10:30 AM-12:00 PM, Big Sur

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