The variation of temperature and salinity within Arctic leads during the summer

Temperature and salinity were measured within Arctic leads during a two-month period during the summer of 1998 as part of the SHEBA field experiment. Underway measurements at a depth of 15 cm were made with a CTD mounted on the bow of a 3-m skiff. In addition, profiles of temperature, salinity and optical properties were made with a second CTD on sections across the lead. Daily measurements were made primarily in the same lead, but on several occasions temperature and salinity profiles were also measured in several leads with a CTD lowered from a helicopter. When the melt season began, a fresh layer with very low salinity (2 psu) and temperature well above freezing (2 C) formed at the surface of the lead. This layer persisted and grew to a depth of over 1 m until it was mixed into the upper ocean by the action of a passing storm in late July. The focus of this paper is on the horizontal variation of temperature and salinity within the lead and the relationship of the variability to depth, distance from the lead edge, ice velocity, and air-lead exchanges of heat and momentum. Helicopter measurements in multiple leads illustrate the effect of lead age (time since opening) on temperature and salinity.