Modulational Instability of Nonlinearly Interacting Incoherent Sea   States
  The modulational instability of nonlinearly interacting spatially incoherent Stokes waves is analyzed. Starting from a pair of nonlinear Schroedinger equations, we derive a coupled set of wave-kinetic equations by using the Wigner transform technique. It is shown that the partial coherence of the interacting waves induces novel effects on the dynamics of crossing sea states. 
P. K. Shukla, M. Marklund, L. Stenflo