Iceberg B31, as big as a city, could move into shipping lanes

A research team led by Grant Bigg of the University of Sheffield has been tracking the ice island with synthetic aperture radar and visible satellite imagery, while also modeling the drift of the ice.

“It has been very interesting how little sea ice there has been in the area,” Bigg said. “In the video, you can certainly see clouds suggesting strong katabatic wind flow off the glacier in the first month or two, which would have kept the Bay ice-free and helped guide the iceberg out.”

“B31 has been well-tracked,” said David Jones of the British Antarctic Survey (BAS). In January 2013, a few months after a rift was detected in the ice shelf of Pine Island Glacier, Jones and colleagues flew over the region and dropped 37 javelin-shaped Aircraft Deployable Ice Observation Systems (ADIOS) onto the ice. ADIOS is basically a GPS tracker, and it is helping researchers monitor the glacier’s movements. Two of the ADIOS javelins were dropped on top of B31 before it broke off from the continent. “Thanks to the early detection of its calving by the IceBridge program, we have been able to study its dynamics from early on in its lifecycle.”

“We are doing some research on local ocean currents to try to explain the motion properly. It has been surprising how there have been periods of almost no motion, interspersed with rapid flow,” Bigg added. “There were a couple of occasions early on when there might have been partial grounding or collisions with the seafloor, as B31 bounced from one side of the Bay to the other.”

“While some mass was lost very early on in the life of B-31, it has remained pretty much the same shape since early December and is still about six times the size of Manhattan,”

NIC last observed B31 at 72° 23′ South latitude, 108° 03′ West longitude. Bigg added that “the iceberg is now well out of Pine Island Bay and will soon join the more general flow in the Southern Ocean, which could be east or west in this region.”