gTr_Surf2kLev = dSPvolSurf2kLev(i,j,k,bi,bj) * SurfVal
& ( gTr_Surf2kLev + gTr_Below2kLev + gTr_kLev2Above )
& ( gTr_Surf2kLev + gTr_Below2kLev)
_RL gTr_Surf2kLev, gTr_Below2kLev, gTr_kLev2Above,