Research Summaries

Back Long Term Observations of Inertial Waves and Turbulent Diffusivity in the Upper Pycnocline of the Beuafort and Chukchi Seas

Fiscal Year 2018
Division Graduate School of Engineering & Applied Science
Department Oceanography
Investigator(s) Shaw, William
Sponsor Office of Naval Research (Navy)
Summary We propose to modify well proven Autonomous Ocean Flux Buoys to extend their measurements of heat, salt and momentum turbulent fluxes just below the ocean/ice interface (e.g. Stanton et al 2012) to include observations of pycnocline diffusivity over a 6m layer well within the seasonal pycnocline, 50m below the ice floe supporting the buoy. A 7m long faired instrument frame (Figure 2) supports three sets of sensors which will be continuously sampled as they drift with the ice for approximately one year (see http://www.oc.nps.edu/~stanton/fluxbuoy/index.html) . The frame consists of top and bottom T/C sensors, and three 2m spar sections that support precision temperature sensors. In the middle of each section a fp07 (7ms fast response) thermistor sampled at 200 Hz measures thermal microstructure down to mm scales, resolving the thermal dissipation cutoff scale. This allows thermal variance dissipation rates, ? to be estimated every 2 minutes from the reported thermal wavenumber spectra. Precision T/S measurements (pumped MicroCat T/C sensors) at the top and bottom of the frame define the mean density gradient for this layer, while 18 temperature sensors spanning the frame resolve both the mean thermal gradients, finescale thermal structure and vertical strain rates, all reported as 120 second ensembles with 10 ?K resolution. Advective velocity of the frame through the water is determined from the ADCP current profiler (to scale the ? calculation), which is part of the current AOFB instrument suite, while the vertical gradient of the current profile provides estimates of the shear across the frame. The modified Pycnocline AOFBs (PAOFBs) will continue to be deployed adjacent to a WHOI Ice Tethered Profiler to provide water column T/S structure and hence stratification and heat content either side of the diffusivity frame every 3 hours.
Keywords Arctic Oceanography Ocean-Ice Interaction Pycnocline Mixing Upper Ocean Turbulence
Publications Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal
Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal