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Lines depicting where ship-based soundings have been made radiate from the Hawaiian Islands. They are part of an update of Google Earth's ocean terrain. |
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Internet
information giant Google updated ocean data in its Google Earth
application this week, reflecting new bathymetry data assembled by
Scripps Institution of Oceanography, UC San Diego, NOAA researchers and
many other ocean mapping groups from around the world.
The
newest version of Google Earth includes more accurate imagery in
several key areas of ocean using data collected by research cruises over
the past three years.
"The
original version of Google Ocean was a newly developed prototype map
that had high resolution but also contained thousands of blunders
related to the original archived ship data," said David Sandwell, a
Scripps geophysicist. "UCSD undergraduate students spent the past three
years identifying and correcting the blunders as well as adding all the
multibeam echosounder data archived at the National Geophysical Data
Center in Boulder, Colorado."
"The
Google map now matches the map used in the research community, which
makes the Google Earth program much more useful as a tool for planning
cruises to uncharted areas," Sandwell added.
For
example, the updated, more precise data corrects a grid-like artifact
on the seafloor that was misinterpreted in the popular press as evidence
of the lost city of Atlantis off the coast of North Africa.
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Discovery Tablemount, South Atlantic Ocean. Google bathymetry with Melville multibeam superimposed.
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Through
several rounds of upgrades, Google Earth now has 15% of the seafloor
image derived from shipboard soundings at 1-km resolution. Previous
versions only derived about 10% of their data from ship soundings and
the rest from depths predicted by Sandwell and NOAA researcher Walter
Smith using satellite gravity measurements. The two developed the
prediction technique in 1994. The satellite and sounding data are
combined with land topography from the NASA Shuttle Radar Topography
Mission (SRTM) to create a global topography and bathymetry grid called
SRTM30_PLUS.
This
new version includes all of the multibeam bathymetry data collected by
U.S. research vessels over the past three decades including 287 Scripps
expeditions from research vessels Washington, Melville and Revelle.
UCSD undergraduate student Alexis Shakas processed all the U.S.
multibeam data and then worked with Google researchers on the global
integration.
The
next major upgrade to the grid will occur later this year using a new
gravity model having twice the accuracy of previous models. The new
gravity information is being collected by a European Space Agency
satellite called CryoSat that was launched in February 2010.
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