Structures of spiral rainbands in numerically simulated tropical cyclones

Continued advances in computational technology have made it possible to numerically simulate tropical cyclones with the horizontal grid spacing on the same length scale as individual updrafts and downdrafts (~ 1 km). Explicit treatment of convection in such simulations of tropical cyclones leads to the appearance of many realistic-looking features of tropical cyclones, including spiral rainbands which are banded structures of convection in a spiral shape. However, their structures are yet to be fully verified against observations. This study will examine kinematic and thermodynamic structures of spiral rainbands in numerically simulated Hurricane Bill (2009) by making comparisons to available observations, including those from recent RAINEX program. Sensitivity of the rainband structures to horizontal and vertical grid spacings, and microphysics and boundary layer parameterizations will be explored as well.