My current work focuses on the momentum budget in the Southern Ocean, a dynamically unique region that governs much of the carbon and heat exchange between the deep ocean and the atmosphere. I use basin-scale model data from the Southern Ocean State Estimate (SOSE) to give a large-scale dynamical context to what we can see in regional observations from the cDrake Experiment.
Wind forcing at the surface of the Southern Ocean provides the momentum source, pushing the fluid eastward. Most (95%) of this momentum exits the ocean via topographic form stress, wherein the solid earth pushes back (westward) on the eastward flowing fluid (details here). The image below shows the six-year time mean wind stress field and topographic form stress field from SOSE, looking north from Antarctica. South America appears on the right, Australia in the middle, and the southern tip of Africa on the very top left; black lines show the mean Antarctic Circumpolar Current streamfunction.
We are now working with basin-scale SOSE data and observational data from the Drake Passage to identify the mechanisms by which momentum is carried from source to sink.
More than half of momentum input at the surface appears to reach the seafloor on short timescales (<10 days) via barotropic waves moving through the system. The rest of the surface momentum input may be carried by interfacial form stress, a mechanism that influences the structure of the upwelling branch of the Meridional Overturning Circulation. The plot below shows hot spots of winter variability of interfacial form stress across the neutral density surface γ = 28.2 kg/m3, roughly the interface between Lower Circumpolar Deep Water and Antarctic Bottom Water.
Masich, J., T. K. Chereskin, and M. R. Mazloff (2015), Topographic form stress in the Southern Ocean State Estimate, J. Geophys. Res. Oceans, 120, 7919–7933, doi:10.1002/2015JC011143. Link.
Masich, J., Mazloff, M. R., and Chereskin, T. K. Interfacial form stress in the Southern Ocean. In prep.
Masich, J., Chereskin, T. K. and Mazloff, M. R. (2015), Topographic form stress in the Southern Ocean State Estimate.
J. Geophys. Res. Oceans. doi:10.1002/2015JC011143.
Masich, J., M. Mazloff, and T. K. Chereskin. Interfacial form stress in the Southern Ocean. In prep.
Masich, J., T. K. Chereskin, and M. R. Mazloff. Momentum balance in the Southern Ocean. PC14D-2091, 2016. Poster presentation at Ocean Sciences Meeting, New Orleans, LA, Feb 2016.
Masich, J., T. K. Chereskin, and M. R. Mazloff. Sources and sinks of momentum in the Southern Ocean State Estimate. 80363, 2015. Poster presentation at American Geophysical Union Fall Meeting, San Francisco, CA, Dec 2015.
Millar, J. J., T. K. Chereskin, and D. R. Watts. Four-year observations of interfacial form stress in the northern Drake Passage. 14505, 2014. Poster presentation at Ocean Sciences Meeting, Honolulu, HI, Feb 2014.
Millar, J. J., T. K. Chereskin, and M. Mazloff. Exploring the Southern Ocean State Estimate in the Drake Passage: Assimilation and Analysis of an Inverted Echo Sounder Array. Oral and poster presentation at C-SOBOM NSF Science and Technology Center review Student and Postdoc Symposium, Princeton NJ, Oct 2012.
Millar, J. J., S. T. Gille, J. Sprintall, and M. Frantz. Assessing XCTD fall-rate errors using concurrent XCTD and CTD profiles in the Southern Ocean. OS21F-1565, 2010. Poster presentation at American Geophysical Union Fall Meeting, San Francisco CA, Dec 2010.
Millar, J. J. and R. W. Schmitt. Parameterizing the mixing due to salt fingers. 873, 2008. Poster presentation at Ocean Sciences Meeting, Orlando FL, Feb 2008.
Millar, J. J., C. Orellana, and N. Mujica. Experimental characterization of supercritical bifurcation in the presence of noise. Poster presentation at the Southern Workshop on Granular Materials, Vina del Mar, Chile, 2006