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Motivated by heightened interest in the role of polar regions in climate and global change, a group of scientists from various institutions and disciplines recently conducted a joint field study of the crack-like openings called leads that are created by deformation of the Arctic pack ice. The study, called the Lead Experiment, known as LeadEx, was conducted during March and April 1992 in the Beaufort Sea approximately 300 km north of Deadhorse, Alaska. Sponsored by the Office of Naval Research, it was designed to clarify the effect of open leads on the polar ocean and atmosphere.

Ranging from a few meters to thousands of meters wide, leads have been long considered important to the thermodynamics of the polar regions. Because a winter lead exposes relatively warm water to the cold atmosphere, either directly or through a very thin layer of ice, leads can account for half the total heat flux from the ocean [Badgley, 1966], even though they occupy less than 10% of the surface area. Open leads, thin ice (<1.0 m), and thick ice (>1.0 m) may contribute equally to the total heat flux [Maykut, 1978]. Because salt is rejected as seawater freezes, leads have a major effect on the salinity of the ocean mixed layer.