Quadrant distribution of tropical cyclone inner-core kinematics in relation to environmental shear

Airborne Doppler radar data collected in tropical cyclones by National Oceanic and Atmospheric Administration WP-3D aircraft over an eight-year period (2003-2010) is used to statistically analyze the vertical structure of tropical cyclone eyewalls with reference to the deep layer environmental shear. The diversity of storm intensities and environmental shear magnitudes allow determination of the interaction between shear and convection in a variety of shear environments. Analysis of the radar reflectivity and vertical motion indicates that convective evolution within the inner core generally conforms to patterns shown by previous studies: convection initiates downshear-right, matures downshear-left and weakens upshear. The vertical distribution of radar reflectivity and vertical air motion shown by this dataset indicates details of the interaction. In particular, the data show the development of upper-level downdrafts in conjunction with mature convection downshear-left and a maximum of their frequency upshear-left. Intense updraft and downdraft frequencies also vary with the shear asymmetry. Focus on the most extreme drafts, we find that the strongest updrafts occur primarily within the eyewall. The most intense downdrafts concentrate along the eyewall edges, but exhibit considerable radial variability, being particularly common in the upshear-left quadrant. Composite cross-sections of vertical and radial flow adjacent to the strong updrafts and downdrafts show the strongest updrafts tending to be collocated with low-level inflow and upper-level outflow superimposed on the background flow. In contrast, strong downdrafts occur in association with low-level outflow and upper-level inflow.