f Sign correction of P to S converted reflected waves by determination of the angle of illumination

When we attempt to proces or interpret P to S converted wave reflection data, we often encounter a reversal in the direction of polarization, or a "sign change", due to a reversal in the angle of illumination. It frequently happens that even events from a common specular reflection point will show this sign reversal on different data sets, or gathers. When data sets with reversals are stacked, either before or after migration, this phenomenon may cause destructive interference of desired events. The signal to noise ratio may actually be lower for the stacked events.