ALUM: no longer at INSTAAR

Cheryl Harrison

Cheryl Harrison

Research Associate

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I am a Research Associate at CU Boulder working on modeling oceanic biophysical interactions, including the effects of nuclear war and asteroid impacts on ocean circulation, biogeochemistry and fisheries.

As a postdoc at NCAR I worked on applications of the eddy resolving CESM BEC global ocean earth system model, focusing on two projects:  1) How resolving the mesoscale circulation (10-100 km) affects biological production and carbon export to the deep ocean on global and regional scales and  2) Simulating ocean turtle migration pathways in the same model, applying robotic control methods to back out optimal behavior.

Previously, I worked on biophysical interactions leading to coastal hypoxia (low oxygen) in upwelling systems at OSU. For this work I used a reduced order biogeochemical complexity model to assess how the dominant timescales of biological production, export, and sinking affect retention and focusing of biological material over the shelf bottom, where bacterial decay causes low oxygen events that can kill benthic fisheries.  The fundamental biogeochemical timescales in the coastal ecosystem interact with the physical forcing and the resulting dynamical flow, so that moderate upwelling and mid-shelf return flow provide optimal conditions for developing hypoxia.

For my PhD I used dynamical systems techniques to study transport barriers and biophysical interactions associated with coherent structures in the ocean, using remote sensing and ocean model velocity data. Coherent structures such as eddies, jets and filaments are observed throughout the global ocean. The transport of nutrient-rich water in productive upwelling systems (such as our local California current system) is controlled by these coherent structures, with extensive effects up the food chain. However, coherent structure boundaries have been difficult to map, and their effects on biology are only starting to be fully understood. Lagrangian coherent structures (LCS), a recently developed technique from dynamical systems theory, allow us to identify the framework of structures that control mixing as well as identify persistent transport boundaries important for biophysical interactions. I applied LCS off the California coast, testing their robustness and using them to study coastal mixing with specific emphasis on marine larval transport and settlement. Understanding the kinematics of larval transport (which is currently poorly understood) will help us understand ecosystem dynamics and effectively manage coastal ecosystems.