  Here, we show through a statistical analysis that rogue waves in broadband
non-breaking seas are spatially asymmetric. In addition to the top-down
asymmetry due to nonlinear effects, we show that the two troughs adjacent to
the rogue wave crest are generally of different depths, which is unlike the
conventional picture of rogue waves with symmetric fore and aft troughs often
obtained from model equations. The rogue-wave trough asymmetry is demonstrated
for sea states 4 to 6 on Douglas Sea Scale. Considering the deepest trough
leads to approximately 10% increase in the calculation of the mean rogue-wave
height compared to previous results for rogue waves reported with symmetric
troughs. This implies that estimates of rogue-wave trough-crest amplitudes
based on model equations should be re-assessed upward for all realistic oceanic
conditions.
