Long-term observations of the variability of abyssal plain currents from Ocean Networks Canada’s seafloor observatory.
A NEPTUNE node is located at a central site on the abyssal plain over the Juan de Fuca plate. At this site there is an upward-looking 75kHz acoustic Doppler current profiler and a CTD/O2 sensor. The current profiler provides currents over the bottom 500 m of the water and the CTD/O2 provides temperature, salinity, dissolved oxygen and pressure a few metres above the bottom.
Here we present continuous observations of currents collected over six years. The rich data set shows variability from interannual to tidal time scales. Low-frequency variability of currents that can be modelled as a passage of deep eddies are observed. Water property variability suggest that bottom water heating can initiate the influx of denser water into the basin in a yet to determined periodicity.
The results are preliminary but suggest a much more dynamic setting than expected that can be contrasted dynamics of flow over rough topography at the nearby Juan de Fuca Ridge.