Purple Fringing Artifact
To my knowledge, the only practical optical role for UV filters in digital photography relates not to scatter, but to an artifact known as "purple fringing" (PF). PF is most commonly seen in digital images but also occurs in film images. It typically appears as a multipixel band of bright purple surrounding the peripheral edges of dark objects cast against a bright background. Central edges are spared. Backlit leaves set against a bright sky are a common PF scenario. A widely accepted theory of purple fringing has yet to emerge, but it's most likely a high-order lens aberration akin to but different from run of the mill chromatic aberration, which instead produces soft red and green fringes on opposite sides of affected objects.