International Airgun Modelling Workshop: Validation of Source Signature and Sound Propagation Models – Dublin (Ireland), 16 July 2016

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The Airgun Modelling Workshop is now closed for registrations. Please contact the organisers (Michele Halvorsen, René Dekeling or Michael Ainslie) with a request to join a waiting list in case of cancellations.

BACKGROUND

The possible impact of seismic surveys on marine life has given regulators and scientists a shared interest in quantifying the sound field produced by an airgun or array of airguns. Predictions do not always agree well with measurements, and the reasons for the disagreement are often not understood.  It is necessary to build confidence in model accuracy by demonstrating that the different modelling techniques produce the same solution for a well-specified problem, or if they do not, to investigate the implications of different methods, assumptions or approximations in order to understand how and why they differ. 

Propagation in shallow water and in deep water are both relevant, with different challenges arising from each.  In shallow water there are uncertainties caused by unknown seabed parameters, while in deep water the difficulties are associated with propagation distances of thousands of kilometres.  The near field is of interest because it includes distances that are relevant to potential physiological effects, while  distances beyond the near field, up to tens of kilometres, are relevant to behavioural disturbance; both types of impact are relevant. At even greater distances, of hundreds of kilometres or more, the contribution from airguns to the ambient sound might become an issue, especially in deep water.

WORKSHOP OBJECTIVE
Our purpose is to meet the demand for increasingly precise assessments of environmental impacts, requiring accurate characterization of the airgun array sound field. We choose to start with the shallow water case because for a model comparison we can eliminate uncertainties in model inputs by specifying these inputs carefully.  The specified scenarios for shallow water will include propagation distances from the near field up to a few tens of kilometres from the array.

The specific goals are:

  • to provide  well-specified biologically relevant scenarios for acoustic propagation, involving received sound pressure and particle motion at pre-specified distances from an airgun array in shallow water;
  • to obtain a set of solutions to these scenarios by combining airgun signature and sound propagation models;
  • to provide a comparison of the various model results, to quantify the differences between them, and to provide a description of the causes of these differences;
  • where appropriate, to identify and correct any errors or extreme deviations.

ORGANISING COMMITTEE

Michael A. Ainslie, TNO (michael.ainslie@tno.nl)
Michele B. Halvorsen, CSA Ocean Sciences Inc. (MHalvorsen@conshelf.com)
René Dekeling, Netherlands Ministry of Infrastructure and Environment (rene.dekeling@minienm.nl)

SCIENTIFIC COMMITTEE

Airgun signatures: Robert M. Laws PhD CEng, Schlumberger Gould Research
Propagation of sound: Kevin D. Heaney PhD FASA, OASIS Inc.
Impact of sound: Michele B. Halvorsen PhD FASA, CSA Ocean Sciences Inc.

SPONSORS

The International Airgun Modelling Workshop is sponsored by Rijkswaterstaat of the Netherlands Ministry of Infrastructure and Environment, the E&P Sound & Marine Life Joint Industry Programme, the US National Oceanic and Atmospheric Administration, the US Bureau of Ocean Energy Management, and the Acoustical Society of America.