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Fig. 12 Polar plots showing horizontal variation of amplitudes (cm) and phases ( ◦ ) of diurnal
(top two rows) and semidiurnal tidal constituents (bottom two rows) in MC as seen from bottom
instruments and satellite altimeter (OTIS) data. The legend indicates the site name and mean depth.
Notice differences in scale
Pressure-Measurements of Tides”, BPR-derived harmonic vectors have been subtracted from those higher up in the water column. We subtract these BPR signals
because, as they agree with altimetric tides, we can take them as representative of
surface tides. Therefore, its subtraction from harmonic signals obtained from pressure records higher up in the water column leads to the signal of coherent internal
tides. Semidiurnal tides appear spatially synchronised, and thus appear as standing
waves. The diurnal components (first two rows) show more variations at the bottom.
Those derived from altimetry (OTIS) show a clear and consistent eastward phase
increase (from lmc5 towards lmc8), and also a slight increase in amplitude. By contrast, the BPRs show in general a slight westward phase propagation, although somewhat more erratic. Especially the bottom pressure recorder at lmctrap behaves, as we
shall see later, somewhat differently for most frequencies. Comparing to harmonic
L. R. M. Maas et al.
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Fig. 12 Polar plots showing horizontal variation of amplitudes (cm) and phases ( ◦ ) of diurnal
(top two rows) and semidiurnal tidal constituents (bottom two rows) in MC as seen from bottom
instruments and satellite altimeter (OTIS) data. The legend indicates the site name and mean depth.
Notice differences in scale
Pressure-Measurements of Tides”, BPR-derived harmonic vectors have been subtracted from those higher up in the water column. We subtract these BPR signals
because, as they agree with altimetric tides, we can take them as representative of
surface tides. Therefore, its subtraction from harmonic signals obtained from pressure records higher up in the water column leads to the signal of coherent internal
tides. Semidiurnal tides appear spatially synchronised, and thus appear as standing
waves. The diurnal components (first two rows) show more variations at the bottom.
Those derived from altimetry (OTIS) show a clear and consistent eastward phase
increase (from lmc5 towards lmc8), and also a slight increase in amplitude. By contrast, the BPRs show in general a slight westward phase propagation, although somewhat more erratic. Especially the bottom pressure recorder at lmctrap behaves, as we
shall see later, somewhat differently for most frequencies. Comparing to harmonic