Making observations in a world of drifting ice

Scientist shares her experience of visiting Arctic Circle on board Chinese icebreaker Xuelong

At the end of September, China's seventh Arctic expedition team returned to Shanghai. Of the 128 team members involved, five were from the Ocean University of China in Qingdao, Shandong province and Cao Yong was the only female to make scientific observations on the ice.

"Exploring the mysteries of the North Pole has been my dream since I worked on my PhD program in 2005," she said.

"My husband helped me prepare, offering to look after our baby and enhancing my faith in myself for the journey."

The expedition began on July 11, when the team boarded the icebreaker Xuelong, or "Snow Dragon", and sailed out into the East China Sea. They went through the Bering Sea and entered the Arctic Circle, a world of drifting ice.

Cao was responsible for taking measurements of conductivity, temperature and ocean depth as well as collecting water, ice and snow samples. Most of her observations could be made from the ship, but occasionally she had to go onto the ice to work around scientific observation stations.

The expedition stopped at seven observation stations - one permanent, the rest temporary. Each was visited by the scientists, who had to wear thermal protective suits every time they left the ship. The suits were nicknamed "the penguin costume" because of the way they restricted the wearer's movements. Each suit weighed 4 kilograms.

"We had to carry a sensor and walk across the ice for about three hours at a time, but because of the suits our underclothes quickly became soaked with sweat. If we had stopped walking, we could have frozen," said Cao, adding "there were some challenges, but the expedition also recorded a number of firsts, which we are all proud of."

These achievements included the Xuelong's first deployment of a drift-towing ocean profiler, which collects hydrographic data from the upper layer of the ocean under the ice, the first exploration of the Mendeleyev Ridge by a team from Ocean University, the first time they had photographed melt pond distribution using an unmanned aerial vehicle and the first time they had measured the thickness of sea ice using ground-penetrating radar.

A notable decline in the extent of Arctic sea ice was observed this year, compared with previous expeditions, Cao said.

"In the past, Xuelong could only sail at a speed of 3 to 4 knots in the high latitude ice zone. But this year we reached 7 knots, which could prove the decline of the sea ice," she said.

Li Tao, captain of the seventh Arctic Expedition Group's Team One, said Cao did all the work assigned to her despite the tough conditions.

"In the field she was a tomboy, never saying no to any assignment. She really tested her limits and completed all the intensive work," Li said.

Yet Cao revealed her feminine side when she put her sewing skills to use making a protective cover for sensitive instruments on the ship's deck and repairing a broken trawl net.

"Over 78 days and nights we traveled 13,000 nautical miles. We experienced gales and gusts, bitter cold and big swells, but it was all worth it to collect the valuable data, spot the cute polar bears and see the fantastic northern lights," she said, adding that the expedition's reports and papers will be released by the end of the year.