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Ocean Research


December 2011 Issue

Birth of Underwater Volcano Studied by Spanish Researchers
After detecting the initial seismic movements associated with the birth of an underwater volcano in early October, scientists with Spain's Institute of Oceanography (IEO) only needed 15 days to map its formation in high resolution.

Scientists on board the IEO's ship Ramón Margalef completed the bathymetry in two days by tracing parallel scans. They found the volcanic cone had reached a height of 100 meters, and the lava tongue had been flowing down its side. In 1998, the same area was mapped the oceanographic ship Hespérides. Using a GIS, these older images were superimposed onto those just taken, thus confirming the birth of the volcano.

"This is probably the first time that such a young underwater volcano has been mapped in such high resolution," said Juan Acosta, head of the campaign to study the volcanic cone.

The base of the volcano lies at a depth of 300 meters. It is conical and 100 meters high with a base diameter of 700 meters and a crater width of 120 meters. Scientists have also created graphs of the gas plumes that are consistently coming out of the main crater and the surrounding cracks. For more information, visit www.ieo.es.

Scientists Predict Faster Retreat for Antarctica's Thwaites Glacier
The retreat of Antarctica's fast-flowing Thwaites Glacier is expected to speed up within 20 years, once the glacier detaches from an underwater ridge that is holding it back, according to a study published in October in Geophysical Research Letters.

Thwaites Glacier, which drains into West Antarctica's Amundsen Sea, is being closely watched for its potential to raise global sea levels. Scientists had previously identified a rock feature off West Antarctica that appeared to be slowing the glacier's slide into the sea. But this study is the first to connect it to a larger ridge, using geophysical data collected during flights over Thwaites Glacier in 2009 under NASA's Ice Bridge campaign.

The newly discovered ridge is 700 meters tall, with two peaks—one that anchors the glacier and another farther offshore that held the glacier in place between 55 and 150 years ago, the authors said. For more information, visit www.agu.org.

International Team to Drill Beneath Antarctic Ice Shelf
A team of researchers funded by NASA and the National Science Foundation will travel in December to Antarctica to determine how changes in the waters circulating under an active ice sheet are causing a glacier to accelerate and drain into the sea.

The scientific expedition will be the most extensive yet that has deployed to Pine Island Glacier, a region that concerns scientists because of its potential to cause a rapid rise in sea level. Satellite measurements have shown this area is losing ice and surrounding glaciers are thinning, raising the possibility that the ice could flow rapidly out to sea.

The multidisciplinary group of 13 scientists, led by Robert Bindschadler, emeritus glaciologist of NASA's Goddard Space Flight Center, will depart from the McMurdo Station in Antarctica in mid-December and spend six weeks on the ice shelf.

Scientists have determined the interaction of winds, water and ice is driving ice loss from the glacier. Gusts of increasingly strong westerly winds push cold surface waters away from the continent, allowing warmer waters that normally hover at depths below the continental shelf to rise. Upwelling warm waters spill over the border of the shelf and move along the seafloor, back to where the glacier rises from the bedrock and floats, causing it to melt.

The team will use a hot water drill to make a hole through the ice shelf. After the drill hits the ocean, the scientists will send a camera down into the cavity to observe the underbelly of the ice shelf and to analyze the seabed, which is approximately 1,640 feet below the ice. Next the team will lower an instrument package that includes a profiler, which will move up and down a cable attached to the seabed, measuring temperature, salinity and currents from approximately 10 feet below the ice to just above the seabed.

A second hole will support a similar instrument array fixed to a pole stuck to the underside of the ice shelf. This instrument will measure how ice and water exchange heat. The team also will insert a string of 16 temperature sensors in the lowermost ice to freeze inside and become part of the ice shelf. The sensors will measure how fast heat is transmitted upward through the ice when hot flushes of water enter the ocean cavity.

Sridhar Anandakrishnan, a geophysicist with Pennsylvania State University, will study the shape of the ocean cavity and the properties of the bedrock under the Pine Island Glacier ice shelf through reflective seismology. Measurements will be taken in about three dozen spots using helicopters. For more information, visit www.nasa.gov.

Polluted Atmosphere Linked to Stronger Cyclones in Arabian Sea
Pollution is making Arabian Sea cyclones more intense, according to a study in published in November in Nature. Traditionally, prevailing wind shear patterns prohibit cyclones in the Arabian Sea from becoming major storms. The paper suggests that weakening winds have enabled the formation of stronger cyclones in recent years, including storms in 2007 and 2010 that were the first recorded storms to enter the Gulf of Oman.

Researchers note that weakening wind patterns during the last 30 years correspond with a buildup of aerosols in the atmosphere over India, which deflect sunlight away from the surface, creating dimming at ground level. This dimming may be responsible for more intense cyclones, the study said.

The aerosol buildup creates formations known as atmospheric brown clouds, in which smog from diesel emissions, soot and other by-products of biomass burning accumulate and become widespread to a degree significant enough to affect regional climate.

Because of their large-scale dimming effects, these clouds have a mitigating effect on the warming of the ocean in the region. For more information, visit www.nature.com.


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