Much information contained in Richard Godfrey's reply at:
https://www.mh370search.com/2024/05/05/n...mment-2885
Richard Godfrey on 23 October 2024 at 10:12
@ventus45,
A complete analysis would comprise the full CTBTO data set (without gaps) from HA01 Cape Leeuwin, HA04 La Crozet Islands and HA08 Diego Garcia. There is scientific data from the Australian IMOS system and secret military data from the US SOSUS system. There are infrasound stations at IS04 Shannon Australia, IS06 Cocos Islands and IS23 Kerguelen Islands, that may add useful information to the hydroacoustic stations.
Usama Kadri published the Cardiff University findings in Nature on 2nd May 2024. Out of about two decades of hydroacoustic data available from the CTBTO, a comprehensive study was undertaken of 100 hours of data identified as having the potential for containing signals pertaining to acoustic signatures of aircraft crashing into the sea. Ten historical aircraft accidents that occurred in open sea locations were selected for this study.
The idea was first put forward in 2014 by Dr. Alec Duncan of Curtin University, Australia who is cited in the new research. Nature published an article on 12th June 2014 titled “Sound clue in hunt for MH370”, but the results were inconclusive.
The Comprehensive Test Ban Treaty Organisation (CTBTO) has hydrophone stations around the Indian Ocean. Dr. Tom Kunkle, Dr. Richard Stead and Dr. Ed Fenimore of Los Alamos National Laboratory in the USA have also analysed the data and also say the results are inconclusive.
My co-author Prof. Simon Maskell is the Scientific Advisor to Ocean Infinity for the recently proposed underwater search for MH370 planned for November 2024. He has a member of his team looking at the CTBTO data. Simon reports that it doesn’t look like there’s any positive evidence of the sensors having a confirmed detection of having “heard” the aircraft hit the sea. However, he thinks we can use that “negative information” to help localise the search area. He has someone using models for acoustic propagation through the oceans assessing whether there is anything useful we can extract from the data and the lack of data.
Reply
John Finlay on 23 October 2024 at 11:14
There would only have been noise for the sensors if there was a high speed impact. This “negative information” would support that there was a controlled ditching.
Reply
Richard Godfrey on 23 October 2024 at 11:34
@John Finlay,
I disagree. There would only be noise for the sensors if there was a high speed impact and a SOFAR channel clear of obstacles and the noise was not contaminated by underwater seismic events (Earthquakes, Volcanoes), exploration companies setting of explosives when conducting seismic surveys or ice breaking off from the Antarctic.
The speed of sound in the ocean varies with depth. In the deep ocean at mid-latitudes, the slowest sound speed occurs at a depth of about 800 to 1000 meters and creates the SOund Fixing And Ranging (SOFAR) channel.
Sound is focused in the sound channel because the sound waves are continually bent, or refracted, towards the region of lower sound speed. The SOFAR channel acts like a wave guide for the sound.
The way in which sound speed changes with depth is not the same everywhere in the ocean because the ocean temperature and salinity profiles that determine sound speed can differ greatly from one location in the ocean to another.
Whenever sound reflects from the rough ocean surface or seafloor, some sound energy is scattered and lost. A sound wave that hits the ocean surface or seafloor many times will be too weak to be detected.
Sound that does not hit the ocean surface or seafloor will still lose energy to absorption. Low-frequency sounds lose very little energy to absorption, however. The result is that low-frequency sounds that do not interact with the ocean surface or seafloor can be detected after traveling long distances through the ocean.
The amount of absorption increases as the frequency of the sound increases, and higher frequency sounds are therefore only detectable at shorter distances. The distances at which sounds can be detected depend on the frequency, how loud the source is, and how loud the background (ambient) noise is.
Sound waves traveling in the sound channel follow many different paths. When the sound source and receiver are located at the depth of the sound speed minimum, called the SOFAR or sound channel axis, sound waves travel nearly straight down the axis and cycle above and below the axis, almost reaching both the surface and bottom.
Although sound travels away from a sound source in all directions, only sound traveling away from a source on paths that leave the source at specific angles will reach a receiver at a specific location. The sound waves traveling on these different paths have slightly different travel times. A single explosive source will therefore be heard as a number of separate arrivals, leading to the characteristic signature of a SOFAR transmission building up to a climax.
Sound paths from a source near the surface come together, or converge, creating regions of higher sound pressure at about the same depth as the source every 50-60 km away from it. These regions of higher sound pressure are called convergence zones. In between the convergence zones, there are regions of lower sound pressure called shadow zones.
In addition to the complexities of detecting the crash of MH370 in the SOFAR channel, there is evidence from the 41 floating debris finds recovered to date, which show a large scale disintegration of the aircraft. There are items of debris from the interior and exterior and from every part of the aircraft, nose to tail, fuselage to wings. This was not a soft landing or controlled ditching, like the Hudson River ditching, where the aircraft remained largely intact.
Much obliged Sir – fascinating and illuminating. Thanks for taking the time. 'K'..
https://www.mh370search.com/2024/05/05/n...mment-2885
Richard Godfrey on 23 October 2024 at 10:12
@ventus45,
A complete analysis would comprise the full CTBTO data set (without gaps) from HA01 Cape Leeuwin, HA04 La Crozet Islands and HA08 Diego Garcia. There is scientific data from the Australian IMOS system and secret military data from the US SOSUS system. There are infrasound stations at IS04 Shannon Australia, IS06 Cocos Islands and IS23 Kerguelen Islands, that may add useful information to the hydroacoustic stations.
Usama Kadri published the Cardiff University findings in Nature on 2nd May 2024. Out of about two decades of hydroacoustic data available from the CTBTO, a comprehensive study was undertaken of 100 hours of data identified as having the potential for containing signals pertaining to acoustic signatures of aircraft crashing into the sea. Ten historical aircraft accidents that occurred in open sea locations were selected for this study.
The idea was first put forward in 2014 by Dr. Alec Duncan of Curtin University, Australia who is cited in the new research. Nature published an article on 12th June 2014 titled “Sound clue in hunt for MH370”, but the results were inconclusive.
The Comprehensive Test Ban Treaty Organisation (CTBTO) has hydrophone stations around the Indian Ocean. Dr. Tom Kunkle, Dr. Richard Stead and Dr. Ed Fenimore of Los Alamos National Laboratory in the USA have also analysed the data and also say the results are inconclusive.
My co-author Prof. Simon Maskell is the Scientific Advisor to Ocean Infinity for the recently proposed underwater search for MH370 planned for November 2024. He has a member of his team looking at the CTBTO data. Simon reports that it doesn’t look like there’s any positive evidence of the sensors having a confirmed detection of having “heard” the aircraft hit the sea. However, he thinks we can use that “negative information” to help localise the search area. He has someone using models for acoustic propagation through the oceans assessing whether there is anything useful we can extract from the data and the lack of data.
Reply
John Finlay on 23 October 2024 at 11:14
There would only have been noise for the sensors if there was a high speed impact. This “negative information” would support that there was a controlled ditching.
Reply
Richard Godfrey on 23 October 2024 at 11:34
@John Finlay,
I disagree. There would only be noise for the sensors if there was a high speed impact and a SOFAR channel clear of obstacles and the noise was not contaminated by underwater seismic events (Earthquakes, Volcanoes), exploration companies setting of explosives when conducting seismic surveys or ice breaking off from the Antarctic.
The speed of sound in the ocean varies with depth. In the deep ocean at mid-latitudes, the slowest sound speed occurs at a depth of about 800 to 1000 meters and creates the SOund Fixing And Ranging (SOFAR) channel.
Sound is focused in the sound channel because the sound waves are continually bent, or refracted, towards the region of lower sound speed. The SOFAR channel acts like a wave guide for the sound.
The way in which sound speed changes with depth is not the same everywhere in the ocean because the ocean temperature and salinity profiles that determine sound speed can differ greatly from one location in the ocean to another.
Whenever sound reflects from the rough ocean surface or seafloor, some sound energy is scattered and lost. A sound wave that hits the ocean surface or seafloor many times will be too weak to be detected.
Sound that does not hit the ocean surface or seafloor will still lose energy to absorption. Low-frequency sounds lose very little energy to absorption, however. The result is that low-frequency sounds that do not interact with the ocean surface or seafloor can be detected after traveling long distances through the ocean.
The amount of absorption increases as the frequency of the sound increases, and higher frequency sounds are therefore only detectable at shorter distances. The distances at which sounds can be detected depend on the frequency, how loud the source is, and how loud the background (ambient) noise is.
Sound waves traveling in the sound channel follow many different paths. When the sound source and receiver are located at the depth of the sound speed minimum, called the SOFAR or sound channel axis, sound waves travel nearly straight down the axis and cycle above and below the axis, almost reaching both the surface and bottom.
Although sound travels away from a sound source in all directions, only sound traveling away from a source on paths that leave the source at specific angles will reach a receiver at a specific location. The sound waves traveling on these different paths have slightly different travel times. A single explosive source will therefore be heard as a number of separate arrivals, leading to the characteristic signature of a SOFAR transmission building up to a climax.
Sound paths from a source near the surface come together, or converge, creating regions of higher sound pressure at about the same depth as the source every 50-60 km away from it. These regions of higher sound pressure are called convergence zones. In between the convergence zones, there are regions of lower sound pressure called shadow zones.
In addition to the complexities of detecting the crash of MH370 in the SOFAR channel, there is evidence from the 41 floating debris finds recovered to date, which show a large scale disintegration of the aircraft. There are items of debris from the interior and exterior and from every part of the aircraft, nose to tail, fuselage to wings. This was not a soft landing or controlled ditching, like the Hudson River ditching, where the aircraft remained largely intact.
Much obliged Sir – fascinating and illuminating. Thanks for taking the time. 'K'..