On the Horizontal Extent of the Canada Basin Thermohaline Steps

Abstract

Microstructure profiles of temperatures through the diffusive thermohaline staircase above the Atlantic layer core in the Canada Basin of the Arctic Ocean are used to investigate the horizontal scales of layers. Daily profiles during two periods, 23 March?3 April, and 17?26 April 1985, show that diffusive steps are present throughout the 200 km drift track. A 20 hour series on 22 April, sampled at about 5 profiles per hour, indicates that particular diffusive layers can be traced for at least 600 m. The temperature of some layers varies by up to 0.01°C h?1 (30 m lateral motion); therefore, we cannot reliably trace steps in this location if the sampling distance is larger than about 15 m. Analysis of a longer time series with variable spacing from 0.4 to 5 km indicates that layers can rarely be traced between profiles more than 1 km apart.