Boundary layer roll dynamic and thermodynamic structures as determined by dropwindsondes

Since 1997, 59 dropwindsonde profiles within tropical cyclone eyewalls

have reported extreme horizontal wind speeds (arbitrarily defined as wind

speed > 90ms-1). From these profiles, a schematic of the structure of

the features in which the extreme horizontal wind speed is located is

proposed. The features are located generally on the inner edge of the

eyewall, and curve upward, outward, and upwind with height. They are

in localized regions of relatively high vertical vorticity, and are

usually associated with updrafts and relatively high equivalent

potential temperature, suggesting convective meso- or miso-cyclones.