... depth, and ηn+ .5 is the interfacial displacementbetween layers n and n + 1. The hydrostatic geopotential function isgn+ .5 ηn+ .5 = φn+1− φn, n = 1, . . . , N − 1 , (5. 20) and gn+ .5 = ... ρnρ0 (5. 21)is the reduced gravity for the interface n + .5. The vertical velocity atthe interfaces iswn+ .5 =Dηn+ .5 Dt, n = 1, . . . , N − 1 . (5. 22) And the buoyancy field isbn+ .5 = −2gn+ .5 Hn+ ... characteristics converge on theforward side of the wave and diverge on the backward side. This leadsto a steepening of the front of the wave form and a reduction of its slopein the back. Since V is...