title: Spatial field shifts in ocean acoustic environmental sensitivity analysis.
abstract: This article examines the effects of spatial field shifts in ocean acoustic environmental sensitivity analysis. Acoustic sensitivity studies are typically based on comparing acoustic fields computed for a reference environmental model and for a perturbed model in which one or more parameters have been changed. The perturbation to the acoustic field due to the perturbed environment generally includes a component representing a spatial shift of the field (i.e., local field structure remains coherent, but shifts in range and/or depth) and a component representing a change to the shifted field. Standard sensitivity measures based on acoustic perturbations at a fixed point can indicate high sensitivity in cases where the field structure changes very little, but is simply shifted by a small spatial offset; this can conflict with an intuitive understanding of sensitivity. This article defines and compares fixed-point and field-shift corrected sensitivity measures. The approaches are illustrated with examples of deterministic sensitivity (i.e., sensitivity to a specific environmental change) and stochastic sensitivity (sensitivity to environmental uncertainty) in range-independent and range-dependent environments.
authors.affiliation: School of Earth and Ocean Sciences, University of Victoria, Victoria British Columbia, V8W 3P6 Canada.
authors.forename: Stan E
authors.initials: SE
authors.lastname: Dosso
authors.forename: Michael G
authors.initials: MG
authors.lastname: Morley
authors.forename: Peter M
authors.initials: PM
authors.lastname: Giles
authors.forename: Gary H
authors.initials: GH
authors.lastname: Brooke
authors.forename: Diana F
authors.initials: DF
authors.lastname: McCammon
authors.forename: Sean
authors.initials: S
authors.lastname: Pecknold
authors.forename: Paul C
authors.initials: PC
authors.lastname: Hines