Environmental Physics Support of the Arctic Mobile Observing System (AMOS)
Abstract
The role of climate change on the Arctic Ocean will have important consequences to the world from a military, geopolitical, economic and environmental perspective. The reduction in sea-ice cover will permit year-round transit of surface ship traffic, which is expected to be primarily cargo shipping, with some military and tourism transport. In order for the US Navy to maintain operational control of the ocean near our coastline, particularly the clearing of the region of nuclear launch capable submarines, we must maintain acoustic superiority in a region that is considerably different environmentally than the usual theaters of temperate latitude operations. Naval and acoustic superiority require the understanding of how the environment is changing, particularly the ice cover and the changes in oceanography and background shipping noise. Applied Ocean Sciences (AOS) is pursuing a combination of underwater acoustic model development and environmental awareness algorithms to support this mission. Current US Naval models for Arctic oceanography and under ice acoustics are insufficient to address the growing need of the Arctic as an ASW theater. Applied Ocean Sciences will develop Arctic versions of environmental mission support. With the goal of deploying an AMOS distributed undersea system the acoustic propagation, communications performance and ocean adaptation algorithms will be developed and transitioned to the fleet via the NUWC-Newport Topside-C3. To meet this need for the year from March 2021 to September 2024, AOS proposes the following tasks, which will take the algorithms from a TRL 2 to 5.The three AOS Principal Investigators bring expertise in ocean acoustics, physical oceanography and mission command and control and will focus their efforts on developing algorithms that provide improved mission planning and execution in complex environments.Applied Ocean Sciences (AOS) has developed a fluid-fluid model for the PE which places a realization of the ice-seawater interface (as well as the ice-air interface) above the range dependent ocean. The ice parameters havebeen chosen to match measured data. The ice is hard and attenuative. Two ice roughness probability density functions (pdfs) are used, taken from the observations of Wadhams (Figure 8) sea ice for first year and multi-year ice. This explicitly rough (and lossy) surface takes the appropriate energy out of the water column and scatters sound as it interacts with the sea ice. Examples of the frequency dependent transmission loss (TL) are shown below in Figure 1. The sea ice has little impact on the propagation at 35 Hz, as the 180 m wavelength of sound is insensitive to roughness of 2 m in depth and 50 m spatial coherence in range. At 100 Hz and 800 Hz, however, the story is different. Both the loss of energy and the scattering of the forward field are evident.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2021
- Source ID
- N000142112393
Entities
People
- Kevin Heaney
Organizations
- Office of Naval Research
- United States Navy