Objective Updraft Tracking in Mesoscale Models – Hurricane Rainband Convective Properties

An objective updraft tracking algorithm was developed, taking into account the dynamical properties of moist convection and its vertical continuity. Instead of focusing on microphysical properties to track convection (as in radar applications), we focus on tracking the updraft through vertical velocity continuity in both three-dimensional space and time. This extensible and objective approach allows users to track and examine the properties of individual updrafts as they form and evolve in model simulations.

To test this algorithm, we apply it to convection in the rainband region of simulated hurricanes. For comparison, we use the algorithm in two hurricane simulations: a 2-km horizontal resolution RAMS simulation and a 1-km horizontal resolution WRF simulation. By collecting data in and around these updrafts, we perform basic statistical analyses to determine spatial and temporal trends in the convective structure and local environmental thermodynamics. The rainband convective updrafts in the two simulations show similar features, including convective tilts and integrated local buoyancy, despite their differing model physics and setups.

An additional benefit of this technique is the ability to extrapolate regions of convective initiation. Utilizing simple advective extrapolation, statistics about convective initiation regions in the rainband region have been accumulated and analyzed. Statistically significant differences between long-lived and short-lived convection can be determined statistically.

Although this algorithm code has not yet been released publicly, plans are being made for its release in the near future.