Vorticity Power Law in a Simulated Tornadic Supercell

From hurricanes (or tropical cyclones) to tornadoes, atmospheric vortices range in horizontal scale from hundreds of kilometers to tens of meters. It is a well-known fact that a power law exists relating the radial velocity, as well as its derived vertical vorticity, to a function of the atmospheric vortices’ radii. However, how the power law relationship varies as a function of time and height within a tornadic supercell before, during and after tornadogenesis is still not well understood because previous studies were hampered by the lack of very high spatiotemporal resolution data. Using simulations from a tornadic supercell with a horizontal grid spacing of 50 m and a temporal resolution of 1 min, this study investigates the time-height evolution of the vorticity power law and its relation with tornadogenesis. Consistent with the findings of Cai (2005), preliminary results indicate that an increase in the slope of vorticity power law at low levels was associated with the intensification of the mesocyclone and the slope peaked near the time of tornadogenesis. Moreover, the maximum slope generally occurred below ~500 m AGL, which suggests tornadogenesis first occurs in the lower boundary layer.