Published online 7 July 2011 | Nature | doi:10.1038/news.2011.402

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Gaping holes in data threaten long-term wind and water measurements.

Pirate attacks have become a serious danger to shipping in the Indian Ocean. MOHAMED DAHIR/AFP/Getty Images

Piracy is stopping oceanographers and meteorologists from collecting data vital to understanding the Indian monsoon and rainfall patterns in the United States, researchers say.

Pirate activity off the coast of Somalia has skyrocketed in recent years. The first surge came in 2008, when there were 135 attacks; from January 2010 to January 2011 there were more than 280 reported incidents. Shipping insurers have been increasing the size of the 'exclusion zone' — the region of the Indian Ocean in which vessels must have special insurance to cover them against piracy. The added risk and cost is steadily driving the ships whose weather reports are used in research farther offshore.

As a result, a long-running collection of wind data in the Indian Ocean now has a giant gap, says meteorologist Shawn Smith of Florida State University in Tallahassee. And a project aiming to install an array of buoys in the Indian Ocean is likely to remain unfinished.

Annual forecasts of the Indian monsoon are unlikely to be affected, scientists say, because there are alternative satellite data sources for that. But long-term studies of these climate systems will be affected. "A 'data hole' in such a dynamically important region is a big deal," says Gerald Meehl of the National Center for Atmospheric Research in Boulder, Colorado, who studies climate systems in the tropical Pacific.

“We've recovered equipment with bullet holes.” Michael McPhaden, PMEL



Although there have been no recent reports of attacks on scientists at sea, there have been close calls. "A research ship once had to outrun pirates," says Smith. Researchers are worried that as the pirates increase their range of attack, the impact on science will get worse.

Winds of change

Meteorologists have long tracked the Somali low-level jet, also called the East African jet — a wind pattern that blows from the coast of Africa northeast across the Arabian Sea to India in summer. "It's the primary source of moisture coming in to drive their summer monsoon," says Smith.

Earth-based wind data in this area come from merchant ships that take weather measurements as a matter of course. A map of ship reports from August 2008 reveals a steady stream of traffic along the Somali coast, right through the core of the Somali jet. But in August 2009, an area of about 2.5 million square kilometres is completely barren of observations (see map), thanks to ships moving to a recommended distance of more than 1,100 km offshore to avoid the pirates1. "All of a sudden in late 2008 we saw this giant hole," says Smith. "There are definitely other gaps in our records, but not for geopolitical reasons."

A comparison of data coverage for August 2008 versus August 2009. Click for a larger version. EOS

Smith's group at Florida State University, which produces a monthly wind map of the area for scientific use, used to compare its Earth-based data to results from the QuikSCAT satellite, which used radar to map the shape of surface waves and infer wind speeds. There was usually good agreement between the two, arguably making ground-based measurements less important. But QuikSCAT failed in November 2009. There are alternatives, but some say the WINDSAT instrument on the Coriolis satellite, launched in 2003, has been unreliable for storm systems, and the European ASCAT satellite, launched in 2007, has a coarser resolution and a smaller field of view.

As Florida State University starts to use alternative satellite data to help create its wind maps, says Smith, it will need ground-based data to calibrate the results. And for long-term studies, he adds, there's no replacement for ground-based data. "If you're interested in knowing whether the system has changed over, say, the past 50 years, the only way you can do that is with the surface data, because that's all that existed 20 years ago," says Smith.

Buoy vandalism

A second project affected by piracy is the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA). Similar to counterpart projects in the tropical Pacific (known as TAO) and the Atlantic (ironically named PIRATA), RAMA will use an array of buoys in the Indian Ocean to monitor everything from wind speed to ocean temperatures at depth.

Those data are expected to help understand the Madden–Julian Oscillation — a 30–60 day cycle of wet and dry weather that moves eastwards across the tropical Pacific from the Indian Ocean. This climate system has been linked to Asian monsoons and to flooding on North America's west coast, but what triggers it is poorly understood.

Over the past 6 years, 30 of 46 planned buoys have been installed; 13 of the 16 remaining are in the insurers' exclusion zone. One of the RAMA cruises came within 150 km of a hijacking in 2008, says Michael McPhaden at the Pacific Marine Environmental Laboratory in Seattle, whose lab is heading the project.

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"Now that [piracy] is really heating up, we're exercising a much greater degree of caution," he says. For one research cruise that entered the exclusion zone for a few days in October 2010, he says, the scientists hired a military escort. Other cruises have simply not been attempted. And some of the buoys already installed have been affected. "We've recovered equipment with bullet holes," McPhaden says.

"It's something that many scientists working in this area are concerned about, but we have absolutely no control over it," explains McPhaden, who is frustrated by the problems. "We have challenges already, like fisherman vandalism, and the difficulties of international collaboration. Then you throw in this wild card and it makes it even more difficult. But we're holding course as best we can."