Dynamics of diffusive-convective staircases in the ocean

Diffusive-convective (DC) staircases in the ocean are observed across a wide range of settings, but their formation, structure and persistence are not fully understood. Theories for DC staircases are reviewed to identify mechanisms governing their development and evolution. Staircase evolution through layer merging and possibly interface splitting, including the relationship to background turbulence, is assessed. Oceanographic examples illustrate the variety of settings in which DC staircases are found, and how they can persist under weak turbulence but are disrupted when turbulence becomes sufficiently strong. Key open questions are identified, highlighting the challenge of linking small-scale processes to the large-scale coherence and persistence of DC staircases in the ocean. This article is part of the theme issue 'Anti-diffusive transport and layering: from sub-cellular to astrophysical scales'.