Since the hounds picked up its scent again last July, an iceberg the size of Rhode Island has sparked growing unease as it inches toward the busy shipping lanes off the tip of South America. Now the berg, dubbed B-10A, has a companion: A-22B, a similarly sized superberg. Both promise to fissure and calve in the coming months, spawning hundreds of progeny that could threaten sightseeing cruises and antarctic resupply ships.
It may sound an easy task to track bergs of such immensity, but B-10A went missing last winter. The U.S. Defense Meteorological Satellite Program, which surveils monster bergs from the sky most of the year, puts on its night goggles during the dark antarctic winter and sniffs out icebergs from the heat differences between ice and water. But thermal sensing can't penetrate clouds, which happened to be thick last winter.
Now scientists have a new tool for finding wayward icebergs. Last summer, David G. Long of Brigham Young University in Provo, Utah, was imaging sea ice in the southern ocean using NASA's SeaWinds scatterometer, which analyzes the backscatter of radio waves off ocean waves to measure wind speed across the water's surface. Not looking for the missing B-10A, Long nonetheless found it on his first radar run. Now he's using the method to analyze how B-10A influences the world around it: Through unknown mechanisms, the superberg is changing its own low cloud cover. Cloud veil or no, the berg can run, but it can't hide.
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