The School of Earth and Atmospheric Sciences presents Dr. Kurt Polzin, Woods Hole Oceanographic InstitutionA Brazil Basin RepriseA series of recent modeling studies (Drake et al. 2022, Ogden and Ferrari submitted, Ledwell submitted) concerning an iconic tracer release in the Brazil Basin (Polzin et al. 1997, Ledwell et al. 2000) document levels of  diapycnal mixing required to explain the long term dispersion of the tracer about its target surface.  The required mixing is inconsistent with microstructure observations obtained during the experiment.  This inconsistency has helped sustain a community myth about “Missing Mixing”.  This presentation will discuss the details of the tracer injection effort, leading to the conclusion that the the microstructure observations need to be taken at face value and are likely consistent with the tracer dispersion.  The presentation will conclude by discussing ongoing and future efforts to address what is missing from the observational record:  the near boundary coupling of the bottom boundary layer to the internal wavefield above steep and rough topography.