Isopleths (Hovmoller Diagrams) of the sea-level variation on latitudinal or longitudinal sections demonstrate specific points in which the sea level is stationary (nearly zero values of the sea-level heights) for a time interval. A phase discontinuity of the sea-level variation takes place near such points, which results, because of the phase jump, in converting wave crests into troughs. In general, the wave movement pattern may be said to consist of standing-progressive waves, or more specifically, Rossby's, on accounting their spatial-temporal scales: wavelengths from several kilometers to thousands and periods from several days to several years. A set of sea-level anomaly fields in the northwestern Pacific is taken from the AVISO site, and the seasonal alteration in them is eliminated by filtering out . Meanwhile, longitudinal isopleths drawn by the same data do not contain wave crests testifying of any wave movements. A similar conclusion is suggested by analysis of the wavelet-isopleths (spatial-temporal