Spiral rainbands as seen in numerically simulated hurricanes

The question as to whether spiral rainbands have positive or negative effects on hurricane intensity continues to be debated in the literature. In recent years, numerical simulations of hurricanes have become a useful research tool to examine the effects of spiral rainbands on hurricanes. This is because steady improvements in computational technology have made it possible to simulate tropical cyclones with convective features on the same length scale as individual updrafts and downdrafts. This study examines spiral rainbands as seen in numerically simulated hurricanes and makes comparisons to observed kinematic and thermodynamic structures of spiral rainbands. In addition, we also examine the conclusions from a previous study by the authors (Moon and Nolan 2009, J. Atmos. Sci.) that the observed mesoscale kinematic structures associated with spiral rainbands – such as the overturning secondary circulation, the descending mid-level radial inflow, and the tangential wind maximum on the radially outward side – can be explained by their mesoscale diabatic heating structures. Sensitivity of numerically simulated spiral rainbands in hurricanes to horizontal and vertical grid spacing, and microphysics, planetary boundary layer parameterizations will be examined as well.