Topography of Ice in Nares Strait 2003 to 2012

The last remaining multi-year ice exits the Arctic Ocean via Nares Strait to the west of Northern Greenland. Ice as thick as 15 meters is advected to the south through the 38 km wide channel. For nine years, we measured ice draft every 15 seconds with upward-looking ice profiling sonars in Nares Strait. Concurrent ocean current profiling yields estimates of ice velocity. Combining these with ice draft, we construct along-channel profiles of ice bottom topography from time series measurements. From 2003 to 2012 the presence of multi-year ice more than doubled. We correlate this finding with the ice in Nares Strait becoming more mobile. This increased mobility is caused by the shorter period during which ice arches stop all flux of ice. More specifically, we find the flux of ice to vary from 93 to 972 km³ per year. Our work allows us to identify individual floes, their roughness, as well as their flux on daily to annual time scales.