Hello Caleb,
There is no exact way to do this, but there is an approximate approach. You can try to define a few (dummy) tracers along the water-air interface, maybe associate them with the AMMGID (ALE multi-material group ID) of water. Some tracers may deviate from this interface positions, but hopefully some may be able to stay there. Their positions will give you the info you need. The commands you can try are *DATABASE_TRACER or *DATABASE_TRACER_ALE. Pls give that a try.
Ian Do
You are navigating away from the AIS Discovery experience