Principal Investigator:John F. Gamache
Collaborating scientist(s):
Hugh E. Willoughby
Michael Black
Frank D. Marks, Jr.
Peter G. Black
Christopher Samsury/The Weather Channel



Objective: To document the structure of Hurricane Olivia during the NOAA aircraft research mission conducted on 24 September 1994. To document the evolution of the wind field during the 3+ hours of airborne Doppler observations. 
Rationale: The two most important forecast parameters for tropical cyclones are the future positions of the hurricane (track) and future strength of the winds (intensity). The goal of the airborne mission was to document at 1/2 hour resolution the changes in the tangential, radial and vertical winds, as well as the precipitation structure and intensity, in the core of the storm.

It has been the goal of this experiment (appropriately called the Eyewall Evolution Experiment) since first proposed to document the wind field changes in a storm with increasing winds.  Up until then, the intensification of a hurricane had not been observed by airborne Doppler as well as it was in Hurricane Olivia was on 24 September 1994.

Method: Perform the analysis of wind speed and direction for each of the 7 "snapshots" of the inner core wind field. Document the change with time in the wind field. Note the relationship of wind and reflectivity to average shear of wind within the storm core. 

The analyses show that the overall reflectivity distribution changed little over the 3+ hour period (Figure 1a and 1b). The water under the storm was warm and the mean wind within the core of the storm varied little more than 5 m/s with height (Figure 2), and thus there was little disruption by wind shear.

The structure however was apparently conducive to slow deepening. This can be seen in the progression of radius-height averaged analyses of tangential wind shown in Figure 3.

Last modified: 02/05/00