Manipulating Geophysical Lagrangian Coherent Structures: Theory and Experiment*

Geophysical Lagrangian Coherent Structures (LCSs) act as transport barriers in geophysical flows, hindering proper mixing in coastal areas and potentially leading to ocean forbidden zones. Disrupting or partially breaking these LCSs in coastal regions could alleviate these forbidden zones and improve the health of coastal ecosystems. However, the significant amount of power driving geophysical flows raises key questions about the feasibility of manipulating kilometer-scale LCSs in an energetically viable manner. 

Our theoretical analysis reveals that it is possible to manipulate LCSs using less than 1% of the energy driving the geophysical LCSs. We further demonstrate the practicality of this strategy through experiments conducted in a laboratory setting using thin-layer electromagnetically driven flow. We significantly manipulated the LCSs using just 1% of the energy that drives them. Our findings indicate that geophysical LCSs can be effectively manipulated with only a small fraction of the energy compared to that of the background flow, presenting a promising approach for environmental management in coastal areas.