Les courant moyens - quel rôle jouent-ils dans l'effet Doppler ?

In the ocean, internal waves commonly occur together with other, large-scale (mean) flows. How are the wave properties affected by such mean flows? In the oceanographic literature, mean flows are often said to create a "Doppler shift". It has passed unnoticed, however, that the term "Doppler shift" is being employed in an ambiguous way. Upon closer examination, it appears that two quite distinct concepts of ''Doppler shifts'' feature in the literature; they are sometimes conflated, resulting in erroneous interpretations.