  Pollution plume monitoring using autonomous vehicles is important due to the
adverse effect of pollution plumes on the environment and associated monetary
losses. Using the advection-diffusion plume dispersion model, we present a
control law design to track dynamic concentration level curves. We also present
a gradient and divergence estimation method to enable this control law from
concentration measurement only. We then present the field testing results of
the control law to track concentration level curves in a plume generated using
Rhodamine dye as a pollution surrogate in a near-shore marine environment.
These plumes are then autonomously tracked using an unmanned surface vessel
equipped with fluorometer sensors. Field experimental results are shown to
evaluate the performance of the controller, and complexities of field
experiments in real-world marine environments are discussed in the paper.
