Modeling of seismic exploration noise reduction in the Marginal Ice Zone
Invited paper
Norwegian Defence Research Est. (FFI)
Tuesday 2 june, 2015, 15:00 - 15:20
0.8 Rome (118)
Abstract:
This paper presents measurements and modeling of ambient noise from recordings
in the Marginal Ice Zone (MIZ) of the Fram Strait, with focus on noise due to
distant seismic exploration. A P-3C aircraft mission flown in June 2011
deployed twenty sonobuoys in the MIZ from open water to within the ice cover.
Data were analyzed for low-frequency (10 Hz - 1 kHz) noise levels, with noise
attributed to distant seismic exploration identified. A reduction of these
levels with distance into the MIZ has been observed and explained in terms of
attenuation due to the ice cover. Propagation loss in the ocean-ice
environment
of the MIZ is modeled using a raytrace numerical model that includes range-
dependent reflection loss due to an elastic ice cover. Environmental input to
this modeling is taken from the TOPAZ4 ocean data assimilation system and from
satellite images. Propagation loss, sea-ice reflection loss, and noise
reduction dependence on sea-ice parameters and distribution is modeled and
discussed.