Upwelling fronts: implications and unknowns

Existing observations of coastal upwelling fronts and of upwelling filaments are reviewed. Attention is given to isolating those aspects where dynamic understanding and knowledge of physical-biological coupling are weak. Theoretical results are then reviewed with the goal of providing some insight on those issues. In view of shortfalls in present knowledge, two interdisciplinary field studies are suggested to examine the stability of upwelling fronts and the mechanisms of exchange across them.