Steering dynamics of hurricanes based on satellite-derived far-field winds

It is known from vorticity dynamics that a vortex line moves with a speed equal to the environmental flow at the vortex location. Equivalently, a “vortex” such as a hurricane can often be resolved into an axisymmetric (azimuthal) component and a dipolar component that convects the vortex pattern. This fact has motivated many researchers since the late 50’s to determine the hurricane steering flow and steering level.

However, in the last decade, it has become clear that the dynamics of a hurricane are strongly influenced by boundary conditions at the ocean surface as well as in the upper troposphere (potential vorticity anomaly).

In this work, we propose to evaluate the steering dynamics of hurricanes using the far-field winds obtained from satellite imagery. Instead of attempting to identify a steering flow or potential vorticity in a complex flow pattern near the hurricane core, we envision to make use of the smoother synoptic-scale winds to deduce the dynamics of the hurricane. The research is based on recent work (Noca et al. 1999, J. Fluids Struct. Vol 13, pp 551-578) which provides the tools for evaluating the dynamics of bodies or bound vortices, using far-field flow velocity information. The proposed methodology removes the need for identifying boundary conditions and for resolving complex, three-dimensional flow patterns near the hurricane center.