MH370 spur to 'better ocean mapping'

 
Bluefin-21 The Bluefin-21 sub aborted its first dive because it was about to exceed its depth limits

Scientists have welcomed the decision to make all ocean depth data (bathymetry) gathered in the search for missing Malaysia Airlines flight MH370 publicly available.

A detailed survey of 60,000 sq km of seabed is to be undertaken to help refine the hunt for the lost jet.

The depth and shape of Earth's ocean floor is very poorly known.

Leading researchers say the MH370 example should be a spur to gather much better data elsewhere in the world.

The search has been hampered by the lack of a high-resolution view of the bed topography west of Australia.

This was apparent on the very first dive made by an autonomous sub investigating possible sonar detections of the aircraft's cockpit voice and flight data recorders.

It was forced to cut short the mission because it encountered depths that exceeded its operating limit of 4,500m. There are places thought to exceed 7,800m.

Australian Transportation Safety Board (ATSB) officials said this week that an area in the southern Indian Ocean the size of Tasmania would now be subject to a full survey using multibeam echo sounders (MBES).

A Chinese navy vessel, Zhu Kezhen, has already started on the project. It will be joined by a commercial ship in June, with the work likely to take three months.

Drs Walter Smith and Karen Marks have assessed the paucity of bathymetric data in the region in an article for EOS Transactions, the weekly magazine of the American Geophysical Union.

The pair work for the US National Oceanic and Atmospheric Administration (Noaa).

They say only two publicly accessible data-acquisition sorties have been conducted close to where search vessels made possible black box detections, and "both expeditions occurred prior to the use of modern multibeam echo sounders, so depth measurements were collected by single, wide-beam echo sounders that recorded on analogue paper scrolls, the digitizing of which is often in error by hundreds of metres".

Modern MBES uses GPS to precisely tie measurements to a particular location. The equipment can not only sense depth very accurately (to an error typically of 2%), but can also return information on seafloor hardness - something that would be important in looking for wreckage in soft sediment.

Just 5% of a vast region, 2,000km by 1,400km, which includes the search locality, has any sort of direct depth measurement, Smith and Marks say.

The rest - 95% - is covered by maps that are an interpolation of satellite data. These have a resolution no better than 20km. Maps of the arid surface of Mars are considerably better.

Ocean floor The depth numbers in the map are estimates, with 95% of the view built from satellite altimetry data

"The state of knowledge of the seafloor in the MH370 search area, although poor, is typical of that in most of Earth's oceans, particularly in the Southern Hemisphere," the pair write.

"In many remote ocean basins the majority of available data are celestially navigated analogue measurements because systematic exploration of the oceans seems to have ceased in the early 1970s, leaving the ocean floors about as sparsely covered as the interstate highway system covers the United States.

"When these sparse soundings are interpolated by satellite altimetry, the resulting knowledge of seafloor topography is 15 times worse in the horizontal and 250 times worse in the vertical than our knowledge of Martian topography."

Smith and Marks hope that the detailed survey work now being conducted in the search for MH370 will be a catalyst to gather better data in other parts of the globe.

High-resolution bathymetry has myriad uses.

"Better knowledge of the ocean floor means better knowledge of fish habitats. This is important for marine conservation, and could help us find biological resources including new medicines," Dr Smith told BBC News.

"It means also a better ability to assess the mineral resource potential of the seabed. And it means better knowledge of the obstacles to flow that cause turbulence and mixing in the oceans.

"We need this mixing and circulation information to make good models of future climate. All of these things depend on knowing the topography of the sea floor."

The Australian Joint Agency Coordination Centre, which disseminates all information on the hunt for MH370, confirmed that the MBES survey data would be publicly available.

"The bathymetry data gathered in the course of the search for MH370 will become the property of the Australian Government. Recognising the importance of that data, it will be made available to the public via both Australian and international databases," the JACC told the BBC.

Interpolation of ocean-floor shape by satellite

Measuring the seafloor graphic
  • Most ocean maps are derived from satellite altimeter measurements
  • Satellites infer ocean-floor features from the shape of the sea surface
  • They detect surface height anomalies driven by variations in local gravity
  • The gravity from the extra mass of mountains makes the water pile up
  • In lower-mass regions, such as over troughs, the sea-surface will dip
  • Limited high-resolution ship data has calibrated the satellites' maps

On Tuesday, all the raw satellite data from the London telecommunications company Inmarsat was also put in the public domain.

It was this information that led investigators to look for wreckage in the southern Indian Ocean.

 
Jonathan Amos, Science correspondent Article written by Jonathan Amos Jonathan Amos Science correspondent

More on This Story

Comments

This entry is now closed for comments

Jump to comments pagination
 
  • rate this
    0

    Comment number 59.

    If indeed the above is the correct search zone
    the plane turned east (off the handshake arc)
    towards land, possibly Learmouth (under pilot
    control), but had to ditch due to fuel depletion.

    My suspicion to this day.

    Who, what and why brought them to that point
    hopefully time will tell to bring closure to all the
    families and friends so traumatically affected.

  • rate this
    0

    Comment number 58.

    #56 AnEnquiringMind, #54 Paul

    You would think given todays technology and five minutes that you could design something better. -
    Single unified recorder stream, dual or quad redundancy, flash drives as storage -
    10 redundant storage units throughout plane. Some with beacons, some float, .. survive high pressure, high temperatures.
    Can design flash drives to survive a 10,000 gravity impact.

  • rate this
    +2

    Comment number 57.

    An amazing legacy to come out of such a terrible tragedy.
    This data will be invaluable in creating better bathymetric maps so perhaps future searches may be more fruitful. I would hope that this can give some comfort to the families, knowing that their loss will in some small way enrich us all.

  • rate this
    +1

    Comment number 56.

    "Black Boxes" = Cockpit Voice Recorder and other Technical Boxes
    positioned in the tailplane of an aircraft, the tailplane being the first
    in a ditch, as opposed to a pitch, good or bad, to take the brunt of the impact.

    Ok?

  • rate this
    +4

    Comment number 55.

    48.David Evans
    "...seems the only plausible explanation"
    -----------------------------------

    Apart from all the other much more plausible explanations, you mean?

    Ridiculous!

 

Comments 5 of 59

 

Features

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.