All the above equations are for
*downgoing*
waves.
To get equations for
*upcoming*
waves you need only change the
signs of *z* and .Letting *D* denote a
*downgoing*
wavefield and *U* an
*upcoming*
wavefield, equation (), for example,
is found in Table .7.

Using the exploding-reflector concept, it is the upcoming wave equation that is found in both migration and diffraction programs. The downgoing wave equation is useful for modeling and migration procedures that are more elaborate than those based on the exploding-reflector concept.

12/26/2000