RADAR ALTIMETER S on-board
the Jason-1, TOPEX, Envisat, and GFO
satellites obtained profi les of sea surface
height on transects across the Indian
Ocean between two and nine hours after
the December 26 Sumatra earthquake.
The data are received hours to days after
“real time,” too late to be used in
detection and warning of tsunamis. We
compared the sea level anomaly profi les
of December 26 measured along the
satellite tracks (Figure 1D-G) with the
measurements on previous passes of the
same satellites 10 days, 35 days, and 17
days earlier. This allowed us to remove
the majority of permanent and slowly
varying features of sea level, revealing
transient signals. The altimeters also
provide wind speed and wave height
data, and these allowed us to interpret a
sea-level anomaly at 16°S in the Jason-
1 profi le (Figure 1D) as being due to a
severe storm. The remaining sea-level
anomaly signal appears to be associated
with the tsunami. The signal of the
leading edge two hours after the earthquake
is particularly prominent, with
an amplitude of 60 cm and two narrow
peaks where the NOAA tsunami model
forecast shows two overlapping peaks
coalescing into one broad (250 km)
crest. Increased sea-surface roughness at
spatial scales from 150 to 15 km wavelengths
also appears inside the portion
of the ocean excited by the tsunami.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84372/1/oceanography_tsunami.pd
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