The coastal ocean most directly links deep water to human society, and as such has long been the subject of fascination, study, and appreciation. The small-scale processes our group focuses on play a dramatic role in the coastal ocean, setting the distribution of everything from pollutants to biologically essential nutrients that underlie the health of our fisheries and nearshore ecosystems.
Some of our work focuses on the role of so-called internal tide ‘solitons’ that are fairly ubiquitous in coastal areas. Many of our projects through the world involve study of internal waves - waves propagating not on the surface but on density interfaces within the ocean interior - often created by tidal flow over topography. When such waves propagate into increasingly shallow water, they often steepen up into very sharp, steep soliton trains. Though the primary action is sub-surface, near-surface convergences and divergences create the appearance of ‘slicks’ on the ocean surface that are often visible. The full complexity of the sub-surface structure of such waves can be visualized with a new fiber optic temperature sensing system, innovative technology developed for this application by MOD group PI's Rob Pinkel and Drew Lucas.
Internal waves play a particularly complex role in the sharp and often deep canyons that are frequently found on the west coast of North America. MOD Project Scientist Amy Waterhouse led 2012 fieldwork along with Ruth Musgrave that investigated internal tide breaking and associated turbulence in Eel Canyon, near Mendocino. ( Read their project website and journal results)
Closer to home, several group members have active projects in La Jolla Canyon, in our own backyard. Here large internal tides interact with mean flows and the sharp canyon bathymetry to greatly enhance the amount of turbulence, and turbulent upwelling of biologically essential nutrients within the canyon. We suspect this why La Jolla Canyon is oft observed to be a biological hot spot.
The complex interaction between coastal currents, their instabilities, internal waves, turbulence, and ecosystems is important not just in canyons, but throughout coastal California and around the world. Amy Waterhouse and MOD Professor Jen MacKinnon are participating in a large Office of Naval Research funded project to assess the interplay of these processes near Point Sal California. MOD graduate student André Palóczy will be leading an affiliated UC Ship Funds project to focus on the role sub-mesoscale coastal current instabilities play in mediating cross-shelf exchange of heat, nutrients and pollutants.