sentence2_structure: Upwelling<>is<>the term for when deep ocean water rises to the surface$$$deep ocean water<>rises<>to the surface
sentence1: Conversely, upwelling zones are areas where the deep ocean water masses emerge to the surface.
sentence2: Upwelling is the term for when deep ocean water rises to the surface.
question: What is the term for when deep ocean water rises to the surface?