We would like to acknowledge D. Williamson for introducing us to the problem of wave 5 in aquaplanets, and M. Blackburn, B. Hoskins, J. Methven, and A. Speranza for useful comments on the setup of the experiments and the interpretation of the results. We also thank an anonymous reviewer whose suggestions helped to improve the paper. GZ gratefully acknowledges the kind hospitality provided by University of Reading. VL acknowledges the financial support provided by the FP7-ERC project NAMASTE (Ref. 257106).
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The phase of the correlation between complex wave amplitudes—also known as complex correlation—is equivalent to the weighted time mean of the phase difference between the two waves, where the weight is the product of the respective amplitudes.
Variations of 10° in the channel’s parameters lead to changes in the correction due to the effect of β < 1 m s−1.