FIRE ISLAND, N.Y. — Starting at the water’s edge, B. J. Reynolds had rolled his surveying pole about 200 feet inland across the beach, the GPS receiver on top producing continuous elevation data that was recorded in a computer in his backpack.

Now Mr. Reynolds, a technician with the United States Geological Survey, had reached the line of dunes that runs the length of the 31-mile barrier island. To complete the elevation profile of this slice of the beach-dune system, he needed to run the equipment to the top.

“When we came out here before the storm, we could walk right up the dune,” Mr. Reynolds said. But that storm — Hurricane Sandy — had obliterated much of the dune, leaving a steep scarp face about 12 feet high. So a colleague from the National Park Service, Jordan Raphael, scrambled to the top, threw down a rope and hauled the pole and backpack up, taking the final measurements.

The work — in all, Mr. Reynolds and Mr. Raphael took about 10 profiles at intervals along the island on two brisk and sparkling days last week — is part of an effort by scientists to take advantage of a storm like no other in recent memory to learn more about how Fire Island, and all barrier islands, respond to and recover from major natural events.