Monday, Feb. 2, 2009 | Google couldn’t have made the big splash it made Monday with its new version of Google Earth — which for the first time includes simulated oceans — without a global map of the ocean floor developed by Scripps Institution of Oceanography geophysicist David Sandwell.

The online, high-resolution replica of the planet that has changed the way people study geography — and spy on their neighbors — now allows users to virtually dive into the ocean and explore the two-thirds of Earth that is underwater from legendary surf spots to remote ocean environments like the Mariana Trench.

The maps needed by Google to make the undersea simulation happen are the result of more than a decade of work by Sandwell, and Walter Smith of the National Oceanic and Atmospheric Administration. They used a combination of depth measurements recorded by ships and a method they developed based on satellite readings to build a model of the seafloor topography, including shelves, canyons and reefs.

“It is really gratifying and enjoyable to see our work presented in such a public way,” said Sandwell in his Scripps Institution office hours after the new version of Google Earth was unveiled at the California Academy of Sciences in Francisco.

Experts said today that the updated Goggle application will dramatically improve ocean research.

“It is hard for me to identify ocean hot spots to present to policymakers,” Serge Dedina, executive director of Wildcoast in Imperial Beach told the Los Angeles Times. “Now I have the capacity to cost-effectively zoom in on my desktop and print what areas need to be conserved and what the potential impact of human activities might have on the area.”

Sandwell’s greatest hope is that the new application reveals just how little we know about the bottom of the ocean, and that it spurs new interest and investment in ocean mapping. Better mapped oceans would give geologists the ability to more accurately predict where the brunt of tsunamis will hit on land, give oceanographers a better understanding of how the depth of the ocean affects tides and perhaps allow biologists to identify new sea species.

“We want to show exactly how poorly mapped the oceans are, especially when compared to the land,” he said.

Google Earth on land has such detail and high resolution that you can see someone sitting inside a parked car. Ocean mapping, which is called bathymetry, is crude by comparison. Even the maps developed by Sandwell and Smith have areas the size of Colorado with little information as to what is under the water. This is because only 10 percent of the ocean floor has been mapped over the decades by ships using sonar technology, which provides the highest level of detail.

Much of this ship mapping has been done near the coasts, which is why the new version of Google Earth has dramatic images such as the canyons that create the renowned surf break at Black’s Beach. To map the remaining 90 percent in this manner would take 120 ship years, or 120 ships working for one year — and cost about $2 billion, Sandwell said.

Lacking the $2 billion, Sandwell and Smith mapped the rest using a method called satellite altimetry, which infers ocean bottom’s topography by measuring the bumps and dips on the surface. The bumps are caused by the gravitational pull that undersea masses create, and the size of the bump on the ocean’s surface determines the size of the mountain under the ocean.

They got as far as they did thanks to data from a satellite launched by the Navy in 1985 after it realized that it would have to measure the tilt of the earth in order to accurately fire nuclear missiles from submarines. And the satellite, beyond identifying the tilt of the ocean’s surface, ended up being useful for other things, Sandwell said.

The Navy declassified the data in 1995, which allowed Sandwell and Smith to begin ocean mapping in earnest. Their project got more funding — and attention — in 2005, after a nuclear submarine crashed into an uncharted undersea mountain in route to Guam from Brisbane, Austrailia. “The Navy realized that they had to know more about what is underneath the ocean,” Sandwell said.

The Navy commissioned an update of the project, which Sandwell and Smith completed in September. Earlier in the year, Google came to the Scripps Institution for a presentation, but were vague about their plans for the updated Google Earth. Sandwell said he didn’t even know until very recently that Google had downloaded the updated maps, which were posted for free on the Scripps Institution’s website.

“Google was doing Google ocean, and voilà, they have this wonderful dataset,” Sandwell said. “Good timing for them.”

Please contact David Washburn directly at david.washburn@voiceofsandiego.org with your thoughts, ideas, personal stories or tips. Or set the tone of the debate with a letter to the editor.

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