A multitude of physical and biological processes occur in the ocean over a wide
range of temporal and spatial scales. Many of these processes are nonlinear and
highly variable, and involve interactions across several scales and oceanic disciplines.
For example, sound propagation is infl uenced by physical and biological
properties of the water column and by the seabed. From observations and conservation
laws, ocean scientists formulate models that aim to explain and predict dynamics
of the sea. This formulation is intricate because it is challenging to observe
the ocean on a sustained basis and to transform basic laws into generic but usable
models. There are imperfections in both data and model estimates. It is important
to quantify such uncertainties to understand limitations and identify the research
needed to increase accuracies, which will lead to fundamental progress
