Fig. 6

Adjusted Feynman diagrams of (a) LSB and (b) USB generations of interactions between the 10-day wave [\(\frac{1}{10d}\),1] and the semidiurnal migrating tide [2cpd,2]. (c,d) Same plots as (a,b) but for the 16-day wave [\(\frac{1}{16d}\),1]. Each panel comprises three arrows, two of which go into a vertex denoting the parent waves and one comes out the vertex representing the secondary wave (SW). Since [f,s] and [\(-f\),\(-s\)] represent the same wave, we use \(f\ge 0\) in the current work to denote all waves. The red solid and blue dashed arrows represent waves exporting and accepting energy in the interaction, respectively, according to the Manley–Rowe relation (e.g. He et al. (2017)). In each panel, the blue arrows’ vector sum equals the sum of the red, entailed by the phase-matching relations