Geoscience Reference
In-Depth Information
T
(a)
(b)
Max
Fig. 6.15 (a) Altimetry sea-level taken along track 129 of the Jason-1 satellite for Cycle 109 and
along the same track 10 days earlier for Cycle 108; and (b) wavelet analysis of the sea level profile
in (a). The theoretical curve, calculated in accordance with the linear dispersion law for surface
gravitational waves, shows the calculated 'onset' moments of the respective spectral components.
Letter “T” indicates the tsunami wavefront (Courtesy of E.A. Kulikov) (see also Plate 15 in the
Colour Plate Section on page 323)
readily singled out in the record of ocean-level variations in time, but not in space.
A sole 'instantaneous shot' of the ocean level along the track is insufficient for
reliable identification of a tsunami wave—it will just be invisible against the back-
ground of other processes. But, by comparing the data obtained from two or more
satellites travelling along the same track with a certain time delay between them,
it is possible to single out a tsunami wave against a noisy background. Anyhow,
such an approach will require significant enhancement of the number of satellites,
equipped with altimeters.
