Extreme waves that appear from nowhere: On the nature of rogue waves

We have numerically calculated chaotic waves of the focusing nonlinear Schrr̈odinger equation (NLSE), starting with a plane wave modulated by relatively weak random waves. We show that the peaks with highest amplitude of the resulting wave composition (rogue waves) can be described in terms of exact solutions of the NLSE in the form of the collision of Akhmediev breathers.