We address the synthesis of distributed control policies to enable a homogeneous team of mobile sensing agents to maintain a desired spatial distribution in a geophysical flow environment. Geophysical flows are natural large-scale fluidic environments such as oceans, eddies, jets, and rivers. In this work, we assume the agents have a 'map' of the fluidic environment consisting of the locations of the Lagrangian coherent structures (LCS). LCS are time-dependent structures that divide the flow into dynamically distinct regions, and are time-dependent extensions of stable and unstable manifolds. Using this information, we design agent-level hybrid control policies that leverage the surrounding fluid dynamics and inherent environmental noise to enable the team to maintain a desired distribution in the workspace. We validate the proposed control strategy using flow fields given by: 1) an analytical time-varying wind-driven multi-gyre flow model, 2) actual flow data generated using our coherent structure experimental testbed, and 3) ocean data provided by the Navy Coastal Ocean Model (NCOM) database.