An Extended Data Set of Hurricane Eyewall Sizes and Slopes

In a previous study, Stern and Nolan (2009) constructed azimuthal-mean wind fields of hurricanes from three-dimensional wind fields generated from pseudo-dual-Doppler observations obtained by the NOAA P3 aircraft and made available to the research community by the Hurricane Research Division. Multiple penetrations (legs) during each flight were composited together to make azimuthal-mean wind fields that were representative over the course of the flight.

It was found that the outward slope of the radius of maximum winds (RMW) as a function of height showed a strong and nearly linear correlation with the size of the inner core (as measured by the RMW at 2 km altitude), and showed no relationship to either current intensity or recent intensity change. These results contrasted with assertions made in previous studies.

For Stern and Nolan (2009), sufficient data was available to construct only 17 azimuthal-mean hurricane wind fields. Since then, more wind fields have become available, from storms observed after the period previously used (2004-2006). The same methods have been applied to these additional data sets resulting in an increase of the number of azimuthal-mean wind fields to 39. In addition to confirming the previous conclusions, the expanded data set has been used to compute the slopes of the eyewall updraft and the 20 dBZ reflectivity surface as an indicator of the eye/eyewall interface. Their relationships to storm size, intensity, and intensity change will be discussed.