Conveners
T1.3 e-poster session: e-poster session - T1.3 - The Oceans and their Properties
- Georgios Haralabus (CTBTO Preparatory Commission, Vienna, Austria)
- Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria)
T1.3 e-poster session: T1.3 - The Oceans and their Properties
- Georgios Haralabus (CTBTO Preparatory Commission, Vienna, Austria)
- Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria)
Description
T1.3
The CTBT IMS hydroacoustic sensor network composed of 6 hydrophone stations and 5 T-phase is part of the global CTBT verification regime. The hydrophone stations consist of hydrophone triplets. Each hydrophone is suspended in the ocean at a depth close to the SOFAR channel axis and anchored by a riser cable to the ocean floor. The geometry of the triplets and dedicated data processing allow...
Despite the progress made both in hardware and numerical techniques, 3D acoustic propagation for stratified oceans in cartesian coordinates, is still a challenge. In 2019, an approach to this problem restricted to short-range distances, using the Boundary Element Method (BEM), was reported (Li et al. J. Comput. Phys. 392, (2019): 694-712.). The BEM is a widespread method that exhibits certain...
The ocean is subject to complex dynamics that can produce time variant sound speed gradients with horizontal scales with potential to impact medium to high frequency acoustic propagation. Some of these features can critical grazing angles that may result in horizontal sound refraction, producing areas of stronger and weaker energy, time delays in the acoustic arrivals and changes on multi-path...
Offshore seismic surveys with airgun array sources are currently widespread in all the oceans. They constitute one of the most powerful and systematic impulsive noise sources in marine environments. The sound pulses from large airgun arrays generate signals that contain sufficient energy in the 5-60 Hz band to propagate ocean-basin scales at ranges of hundreds to thousands of kilometres. Under...
Anthropogenic noise pollution may mask natural sounds, which are fundamental to survival and reproduction of wildlife, especially for marine cetaceans as they are highly dependent on underwater sounds for basic life functions.
In the 21st century, shipping in the ocean has increased significantly and causes low frequency (10–100 Hz) noise which affects or hinders vital communication of...
The hydroacoustic component of the IMS network consists of a series of five island-based seismic stations and six cabled hydrophone installations located in the Indian, Pacific and Atlantic Oceans. In this study, we focus only on hydrophone stations, which provide low back ground high quality data: each one of these stations hosts a set of three hydrophones deployed at a depth of the SOFAR...
The six CTBT IMS hydroacoustic hydrophone stations, comprising 11 triplets in total, record continuous data sampled at 250 Hz. Marine mammal vocalizations are frequently identified in these recordings and form an integral part of the HA stations’ undersea soundscapes, as reported in numerous scientific publications. During regular IMS hydrophone data quality checks, occasional short duration...
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is operating and maintaining the international monitoring system of seismic, infrasound, hydroacoustic and airborne radionuclide facilities to detect a nuclear explosion over the globe. The monitoring network of CTBTO, especially with regard to infrasound and hydroacoustic, is quite unique because the network covers the globe, and...
Following an eruption series at Kadovar Island, Papua New Guinea, the hydroacoustic datasets acquired by CTBT International Monitoring System (IMS) hydroacoustic (HA) hydrophone station HA11, Wake Island, were examined. HA11 is located approximately 3500 km northeast from Kadovar. Active eruptions restarted in January 2018 after a quiet period of three centuries. Cross-correlation analysis...
Abstract: In view of the low accuracy of the far-field modeling of underwater explosion sound propagation, the normal mode-parabolic equation method is used to carry out the modeling of hydroacoustic propagation to optimize the ability of far-field propagation simulation. This method combines the advantages of the normal mode model method and the parabolic equation method, adopts local normal...
The six hydroacoustic hydrophone stations within the CTBTO’s International Monitoring System comprise a total of 11 triplets. These triplets have a 20-year design life with no scheduled underwater segment maintenance actions and are based on a linear non-modular design which offers the advantages of high reliability and efficient deployment in one continuous operation. However, a triplet...
The International Monitoring System (IMS) of the CTBTO includes hydroacoustic stations composed of underwater hydrophones placed at the depth of the SOFAR channel. Since the hydroacoustic component of the network is designed to detect underwater nuclear explosions, events of special interest are impulsive underwater explosions. Among these, we studied several underwater explosions detonated...
On 18 June 2020, energetic underwater acoustic T-phase signals were recorded at the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) hydrophone station HA03, located at the Juan Fernandez Islands, Chile. In this work, we investigate the origin of these T-phases, which were associated to an M7.4 submarine earthquake with epicenter in the Kermadec Trench located...
On 1 October 2015, the cargo ship SS El Faro was lost approximately 120 km east of Long Island, The Bahamas, during the Hurricane Joaquin. Here, we analyze underwater sound phases potentially associated with the loss of this vessel, recorded by station HA10 of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) located at Ascension Island, Mid-Atlantic Ocean....
