Applications of Radar-Derived Shear Products Using an Updated Linear Least-Squares Derivative Technique

The linear least-squares derivative (LLSD) technique is a mathematical method used to calculate the cross-azimuthal component of wind shear, commonly known as azimuthal shear, in Doppler radar velocity fields. Recently, work was completed to optimize the mathematical foundation of LLSD used to compute azimuthal shear, correcting previously documented inaccuracies and resulting in a more exact method of calculation. Operationally, this quantity serves as the basis for the rotation track product generated by the National Severe Storms Laboratory (NSSL), which is widely used to highlight tornado and mesocyclone paths. New work has begun investigating the utility of expanding the use of azimuthal shear in a variety of other radar-based meteorological applications, such as the identification of small-scale, non-supercellular circulations. In addition, exploring the expansion of LLSD use beyond azimuthal shear, applying the technique to the calculation of the along-azimuth component of shear (effectively, two-dimensional divergence) shows promise in a number of applications, including the detection of downbursts and convergent boundaries. This work serves as a summary of applications both presently operational and under development that utilize the LLSD technique to produce velocity-derived shear-based products.