The shear of the outgoing null normal of the dynamical horizon gives a measure of the ingoing flux of transverse gravitational radiation. The behaviour of the shear was studied in a binary black hole scenario and interesting correlations were found between the transverse gravitational modes infalling at the horizon and the transverse modes at null infinity.
Relevant works:
News from horizons in binary black hole mergers [Phys. Rev. Lett. 125121101].
Post merger shear studies.