Thursday, January 26, 2012

Tracking the great Japan tsunami debris field: wood blocks and satellites

In order to better understand the flow of marine debris from the Japan tsunami last year, a team of researchers is using...marine debris.

That is, they have deposited near the leading edge of the debris field a series of satellite-reporting buoys and hundreds of wooden blocks imprinted with a website address and phone number, where beachcombers and boaters who find them can report their location.

(Image: One of the wooden blocks. If you find one, please report where you located it. The address to use is Credit: IPRC.)

The preliminary data from the program is indicating that the debris currently is flowing west-to-east somewhat north of the Northwestern Hawaiian Islands, and thus far has not started coming ashore. More on that at the end of this report.

The marine debris survey is designed to help better understand the likely impacts of the millions of tons of material that was washed into the sea by the March 11, 2011, earthquake and tsunami in Japan.

“One thing is certain: the debris is hazardous to navigation, marine life, and when washed ashore, to coastlines,” said a press release from the International Pacific Research Center at the University of Hawai`i.

Researchers thus far have largely depended on already deployed floaters and computer current and wind models to make estimates of the debris field’s location. They’ve been helped by reports from a few ships that have transited the field.

The models suggested that debris could be arriving in the Northwestern Hawaiian Islands this winter, hitting Midway Atoll and the islands of the Papahānaumokuākea National Marine Monument. Ship reports as early as September showed the debris field just 250 miles northwest of Midway.

Teams from the University of Hawai`i at Mānoa and at Hilo, the Scripps Institution of Oceanography and the Ocean Recovery Alliance, developed a plan to deploy a drifter array across the front of the debris field. They developed 11 satellite-tracked buoys that are designed to mimic the motion of different kinds of debris, and put them in the water between Midway and the debris field. The satellite signals from the buoys will help researchers understand how the field is moving in the local currents of the region.

In a decidedly lower-tech program, they also deployed 400 wooden blocks in the water, each branded with information on how people finding them can respond.

“If boaters, fishermen and beachgoers find these blocks and contact the scientists by the information on the blocks, they will also increase understanding of the motion of debris and currents in this remote region,” the release said.

It added: “Among the most important results of the expedition was the recognition that tsunami debris has recently not advanced towards Midway, but instead has been flowing eastward well to the north of the atolls.

“Analysis of the ocean-current field shows why: For the past weeks, the general flow around all Hawaiian Islands has been from the southwest, producing a front located 300-400 miles northwest of the Midway. This front and associated northeastward jet keep the tsunami debris north of the least for the time being.”

Learn more about the debris tracking project here.

The researchers on the project are Nikolai Maximenko and Jan Hafner of IPRC, Doug Woodring of Ocean Recovery, Luc a Centurioni of Scripps Institution of Oceanography and Hank Carson of the University of Hawai`i at Hilo.

© Jan TenBruggencate 2012

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