Monitoring the volume, freshwater and heat fluxes passing through Lancaster sound in the Canadian arctic archipelago

Abstract

A research project, consisting of instrumentation development and mooring work, has monitored the volume, heat and freshwater fluxes passing through Lancaster Sound, one of the three main pathways through the Canadian Arctic Archipelago. Instrumentation to measure the current direction of the Acoustic Doppler Current Profilers (ADCPs) moored in this region of low horizontal magnetic field strength have been successfully developed and implemented. Time series data from August 1998 to September 2001 of the salinity, temperature and velocity fields and the derived estimates of the volume, freshwater and heat fluxes passing through Lancaster Sound are reported. The fluxes exhibit large seasonal and interannual variabilities. Fluxes are small in fall and winter and reach their maxima in late summer. The seasonal eastward volume flux estimate ranged from a low of ‐0.01 Sv in the fall of 1998 to a maximum of 1.3 Sv in the summer of 2000. Its three‐year mean of 0.75 Sv varies interannually by ±0.25 Sv. Freshwater flux estimates vary similarly with minima in winter and maxima in late summer. They generally are one‐fifteenth of the volume fluxes; but are likely underestimated as their surface freshwater content is based on data from Conductivity‐Temperature‐Depth (CTD) sensors at 25–30 m depth thus missing fresher water above the summer halocline. The pack ice contribution to the freshwater flux is small as most of the year the pack ice is land‐fast; it accounts for less than 5% of the freshwater flux when spread over the entire year.