Aff Starter Pack – Search for mh370
Advantage One – Seafloor Topography
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Advantage One – Seafloor TopographyBackground infoBackground and Thesis for this AdvantageThe word “topography” means “a field of science comprising the study of surface shape and features of the Earth”. “Seafloor topography” means the study of the shapes, twists, turns, and features on the floor of an ocean. The basic gist of this advantage is that humanity does not know very much about the bottom of the Indian Ocean – the area where most believe Flight 370 stands to be located. Even if the aff does not locate MH370, the process of mapping the ocean floor could be of great benefit to science and humanity. “Topographic” knowledge could be quite useful for scientific matters totally unrelated to the missing flight. Better put – this advantage defends the idea that “more knowledge = good” – it can help humanity better prepare for tsunamis and underwater earthquakes. It can help humanity better understand the climate, ecosystems, fishing habitats, etc. All of that knowledge can drive more informed actions by the public, by science, or by government. Top of the AdvantageTop level of AdvContention Two – Seafloor TopographyScience has much to learn about Oceans. 370’s search zone holds unique knowledge gaps vital for better forecasting of natural disasters. Surveys at greater depths are key.Smith & Marks ‘14 Walter H.F. Smith is a Geophysicist in NOAA's Laboratory for Satellite Altimetry and Chair of the scientific and technical sub-committee of GEBCOthis link opens in a new window, the international and intergovernmental committee for the General Bathymetric Charts of the Oceans. Smith earned a B.Sc. at the University of Southern California, M.A., M.Phil. and Ph.D. degrees at Columbia University, and was a post-doctoral fellow at the Institute for Geophysics and Planetary Physics of the Scripps Institution of Oceanography before joining NOAA in 1992. Karen Marks has worked as a Geophysicist since 1990 at the NOAA Laboratory for Satellite Altimetry of the U.S. National Oceanic and Atmospheric Administration in Silver Spring, Maryland, USA. She received a B.S. in Geology from the University of Florida, an M.S. in Geophysics from Boston College, and a Ph.D. in Geophysics from the University of Houston, with a dissertation on the geophysics of the Australian-Antarctic Discordance Zone. – Eos, Vol. 95, No. 21, May 27th 2014 – Full Journal Title is: “Eos, Transactions, American Geophysical Union”. It is a weekly magazine of geophysics. http://onlinelibrary.wiley.com/doi/10.1002/2014EO210001/pdf The depths in Figure 1 are from GEBCO [2010], which uses satellite altimetry to interpolate gaps between ship survey data publicly available in open sources [Smith and Sandwell, 1994, 1997]. The accuracy of the positions and depths in these survey data limits the accuracy of the satellite estimates. In addition, depth estimates from satellite altimetry are most accurate where the seafloor topography is moderate and composed of oceanic crust overlain by less than 200 meters of sediment [Smith and Sandwell, 1994]. Whittaker et al. [2013] estimate sediment thicknesses in the area varying from 12 meters to 1.5 kilometers, and Deep Sea Drilling Project site 256 (gray dot in Figure 1) found 251 meters of sediment [Davies et al., 1974]. The seabed in the MH370 search area records a complex geologic history of the breakup of Australia, India, and Antarctica approximately 130 million years ago [Williams et al., 2013a]. The shallowest depth in the area shown in Figure 1 is about 237 meters on Broken Ridge, a structure related to the separation of Australia and Antarctica whose conjugate, the Kerguelen Plateau, lies on the Antarctic plate. Within the acoustic search zone of Figure 1, the shallowest depth is about 1637 meters at the summit of Batavia Plateau. The deepest point in the area shown also lies within the acoustic search zone, where the trough of the Wallaby- Zenith Fracture Zone plunges to an estimated 7883 meters, just south of the Zenith Plateau. These plateaus are fragments of continental crust, leftovers of Indo-Australian continental breakup [Williams et al., 2013b], and are embedded in old, deep seafloor. The search for airplane debris in the open ocean is not without precedent: On 1 June 2009, Air France flight AF447 disappeared over the Atlantic Ocean. However, the present search for missing Malaysia Airlines flight MH370 takes place under very different circumstances. When AF447 disappeared, there was little doubt about where it would be found. The flight had not deviated significantly from its intended path from Rio de Janeiro to Paris, and the aircraft was routinely sending messages monitoring the health of its flight systems along with its position. Warning and failure messages generated by these systems in the last few minutes of flight helped to locate the crash site, and a surface search there found floating debris and fuel slicks the very next day. In addition, the AF447 crash site was in an area already 100% covered by a previous state-of-the-art bathymetric survey (MBES and GPS), and this knowledge of the undersea terrain helped searchers select and program autonomous underwater vehicles (AUVs) to search for the black boxes. Even so, they were not recovered until nearly 2 years after the crash. In comparison, the MH370 crash site is very poorly known. There are no measured depths in public databases at the locations where ping contacts were reported. Satellite altimetry estimates that depths at the Chinese and Australian contact locations are about 4300 and 5160 meters, respectively, but these estimates are quite uncertain and might be in error by approximately 250 meters or more. Selecting an appropriate AUV and programming its search path require knowledge of the terrain. A Bluefin 21 AUV initially deployed over Zenith Plateau to search for debris, for example, was not designed to operate at depths below 4500 meters. Lack of knowledge of seafloor topography has other consequences. Bottom topography steers surface currents [Gille et al., 2004] while bottom roughness controls ocean mixing rates [Kunze and Llewellyn Smith, 2004], and poor knowledge of these characteristics limits the accuracy of forecasts of everything from the path of floating debris to the path of tsunamis [Mofjeld et al., 2004] and the future of climate [Jayne et al., 2004]. 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. In many remote ocean basins the majority of available data are celestially navigated analog measurements [Smith, 1993] because systematic exploration of the oceans seems to have ceased in the early 1970s [Smith, 1993, 1998; Wessel and Chandler, 2011], leaving the ocean floors about as sparsely covered as the interstate highway system covers the United States [see Smith and Sandwell, 2004, Figure 2]. When these sparse soundings are interpolated by satellite altimetry, as in Figure 1, 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, 2004]. Although a new bathymetric satellite altimeter mission could improve this situation significantly [Smith and Sandwell, 2004], ships with echo sounders remain the best technology for ocean mapping. The global ocean deeper than 500 meters (that is, deeper than the continental shelves) could be fully surveyed with state-of-the art navigation and acoustic multibeam systems with a total effort of about 200 ship-years of vessel activity at a total cost less than that of a typical planetary exploration mission [Carron et al., 2001]. Until there is such an effort, knowledge of Earth’s ocean floors will remain limited to the resolution available from satellite altimetry, which is vastly poorer than our knowledge of the topographies of Earth’s Moon, Mars, and Venus. Perhaps the data collected during the search for MH370 will be contributed to public databanks and will be a start of greater efforts to map Earth’s ocean floor. (Note to students: Air France flight, or AF447, was a 2009 flight that departed from Rio de Janeiro in transit to Paris. It crashed near the coast of Brazil. It took about two years to recover the bulk of the wreckage. As you read about this Aff, you’ll notice that references in AF447 come-up frequently. It is worth noting that science was much more familiar with the seafloor topography of area of the Atlantic Ocean where AF447 crashed…. The phrase “AUV” appears in this card. It means “autonomous underwater vehicle”. Bluefin and CURV are examples of autonomous underwater vehicles…. “Tsunamis” – for those unfamiliar – are “tidal waves”.) This knowledge also boosts information that’s vital to marine conservation and cures from medicinal biodiversity.Amos ‘14 Jonathan Amos, BBC Science Correspondent – internally quoting Walter H.F. Smith and Karen Marks. Both are expert Geophysicists at the NOAA – “MH370 spur to 'better ocean mapping'” – BBC News – May 27th, 2014 – http://www.bbc.com/news/science-environment-27589433 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 publically 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. "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. (Note to students – “Bathymetry” is the study of underwater depth of lake or ocean floors…. “Medicinal biodiversity” is the idea that plants and animals have information in their genetic codes that could be of use when humanity confronts a disease). 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