Analyses of storm-relative winds reveal familiar features, including near-logarithmic wind speed profiles below low-level jets (Franklin et al. 2003; Powell et al. 2003), strong near-surface inflow layers that penetrate the eyewall region (Montgomery et al. 2006; Zhang et al. 2011, 2013), and outward sloping of the eyewall with height (Stern and Nolan 2009; Hazelton et al. 2013; Stern et al. 2014). These kinematic analyses also depict differences between composite groups, seen most notably in the horizontal and vertical extent of the low-level jet, near-surface inflow maxima, and the radial profile of tangential wind. To the best of our knowledge, these differences found in the hurricane boundary layer are new in observational literature. Questions and potential ramifications of these findings---for example, on radial convergence, convection, and possibly intensification---are discussed.
Composited thermodynamic fields illustrate plainly the warm-core nature of hurricanes, nearly moist adiabatic conditions outside of the eye and above the frictional inflow layer, and the reservoir of moist static energy in the low-level hurricane eye. Static stability is variable across composite groups, especially near the top of the frictional inflow layer, in the eyewall region, and in the low-level eye. Equivalent potential temperatures in the hurricane eye and in the lowest 100 m are markedly different between groups. In the context of intensity change, apparent kinematic and thermodynamic signals are broken down to explain physically the differences between composite groups. Hopefully, these explanations will provide guidance and insight for future endeavors to model or otherwise understand the intertwined behavior between a hurricane and its boundary layer.