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Sample records for great meteor seamount

  1. Evidence for age and evolution of Corner seamounts and Great Meteor seamount chain from multibeam bathymetry

    NASA Technical Reports Server (NTRS)

    Tucholke, Brian E.; Smoot, N. Christian

    1990-01-01

    The morphology of the Corner and Cruiser seamounts is discussed and the apparent age of seamount geomorphic features that are thought to have formed at sea level is derived. High-resolution, multibeam bathymetry of the seamounts shows geomorphic features such as guyots and terraces. The pattern of volcanism is consistent with the sequential formation of the New England, Corner, and Great Meteor chain seamounts above the New England hotspot. However, Late Cretaceous and Cenozoic absolute motion of the African plate over the hotspot differs significantly from predictions of the existing models. The derived age pattern of volcanism indicates formation of the Corner seamounts at ca. 80 Ma to 76 Ma.

  2. Evidence for age and evolution of Corner seamounts and Great Meteor seamount chain from multibeam bathymetry

    NASA Astrophysics Data System (ADS)

    Tucholke, Brian E.; Smoot, N. Christian

    1990-10-01

    The morphology of the Corner and Cruiser seamounts is discussed and the apparent age of seamount geomorphic features that are thought to have formed at sea level is derived. High-resolution, multibeam bathymetry of the seamounts shows geomorphic features such as guyots and terraces. The pattern of volcanism is consistent with the sequential formation of the New England, Corner, and Great Meteor chain seamounts above the New England hotspot. However, Late Cretaceous and Cenozoic absolute motion of the African plate over the hotspot differs significantly from predictions of the existing models. The derived age pattern of volcanism indicates formation of the Corner seamounts at ca. 80 Ma to 76 Ma.

  3. Great Meteor Seamount revisited: DETAILED INTERNAL WAVE TURBULENCE

    NASA Astrophysics Data System (ADS)

    van Haren, H.; Gostiaux, L.

    2012-04-01

    Turbulent vertical eddy diffusivity (Kz) and dissipation rate (eps) are estimated between 0.5 and 50 m above a slope of Great Meteor Seamount, Canary Basin, using 101 moored temperature sensors, 1-mK precision, sampling at 1 Hz. Detailed observed time-depth temperature images are split in two: a statically stable and a turbulence image. Averaged over a fortnight, the observed overall time-depth mean Kz=3+-1x10-3 m2 s-1 and eps=1.5+-0.7x10-7 W kg-1. Variations with time and depth are large, by up to four orders of magnitude. Although tidal variations do occur, shorter-scale variations are more intense. A particular tidal period shows multiple vigorous overturning events, the largest found away from the bottom during the downslope phase but just prior to arrival of an upslope moving, equally vigorous bore. The strength of the bore may be controlled by the intensity of the mixing just prior to it. The bore itself is turbulent from the bottom upward, up to some 40 m above it. Its mixing is most efficient providing large fluxes in extremely thin layers.

  4. The heavens on fire : the great Leonid meteor storms

    NASA Astrophysics Data System (ADS)

    Littmann, Mark

    Imagine the night sky so full of shooting stars that the firmament itself seems to be crashing to Earth. When the most spectacular of all meteor showers - the Leonids - passed in 1966, observers saw 40 every second. In 1833, three widely-separated observers described the Leonid storm as `the heavens on fire'. The returning Leonids are now reaching their peak with great activity expected in 1999 and 2000. The Heavens on Fire vividly tells the history of meteors, and especially the Leonids, whose terrifying beauty established meteor science. Mark Littmann traces the history and mythology of meteors, profiles the fascinating figures whose discoveries advanced the field, and explores how meteors have changed the course of life on Earth. He offers advice on how and where to make the best of the 1999 and 2000 Leonid storms. `a must-have for meteor enthusiasts.' Sky and Telescope

  5. Crowdsourcing, the great meteor storm of 1833, and the founding of meteor science.

    PubMed

    Littmann, Mark; Suomela, Todd

    2014-06-01

    Yale science professor Denison Olmsted used crowdsourcing to gather observations from across the United States of the unexpected deluge of meteors on 13 November 1833--more than 72,000/h. He used these observations (and newspaper accounts and correspondence from scientists) to make a commendably accurate interpretation of the meteor storm, overturning 2100 years of erroneous teachings about shooting stars and establishing meteor science as a new branch of astronomy. Olmsted's success was substantially based on his use of newspapers and their practice of news pooling to solicit observations from throughout the country by lay and expert observers professionally unaffiliated with Yale College and him. In today's parlance, Olmsted was a remarkably successful early practitioner of scientific crowdsourcing, also known as citizen science. He may have been the first to use mass media for crowdsourcing in science. He pioneered many of the citizen-science crowdsourcing practices that are still in use today: an open call for citizen participation, a clearly defined task, a large geographical distribution for gathering data and a rapid response to opportunistic events. Olmsted's achievement is not just that he used crowdsourcing in 1833 but that crowdsourcing helped him to advance science significantly.

  6. Spionidae (Polychaeta: Canalipalpata: Spionida) from seamounts in the NE Atlantic.

    PubMed

    Meißner, Karin; Bick, Andreas; Guggolz, Theresa; Götting, Miriam

    2014-04-10

    Spionidae (Polychaeta) collected from seamounts in the Atlantic Ocean were studied. Altogether six species were found of which two are new to science and one belongs to a new genus. Aonidella cf. dayi Maciolek in López-Jamar, 1989 and Glandulospio orestes gen. et sp. nov. were the most common species and occurred on both the Great and Little Meteor Seamount, the Irving Seamount and the Hyeres Seamount. Laonice norgensis Sikorski, 2003 and Malacoceros jirkovi Sikorski, 1992 have a wider distribution in the North Atlantic, including the Mediterranean Sea in case of L. norgensis. Aonides selvagensis Brito, Núñez and Riera, 2006 is only known from the Macaronesian Region. Dipolydora paracaulleryi sp. nov. has been collected from both the Great and Little Meteor Seamounts. All species are compared with morphological similar species and their taxonomy is discussed. Detailed descriptions are provided for the species new to science and descriptions of the previously known species are amended. Accompanying histological studies revealed the presence of very strong dorsoventral musculature in A. cf. dayi and for G. orestes gen. et sp. nov. the presence of glandular organs in the middle body region. Laonice maciolekae Aguirrezabalaga & Ceberio, 2005 was found to be a junior synonym of L. appellöfi Söderström, 1920 and is formally synonymised. Molecular data suggest gene flow between seamounts and autochthonous as well as allochthonous larval recruitment for different species. The results of previous studies by other authors, that polychaete communities of the North Atlantic Seamounts are characterized by low diversity, low rates of endemism, and the predominance of widely distributed (and cosmopolitan) species is not corroborated by our results. 

  7. Meteor Showers.

    ERIC Educational Resources Information Center

    Kronk, Gary W.

    1988-01-01

    Described are the history, formation, and observing techniques of meteors and comets. Provided are several pictures, diagrams, meteor organizations and publications, and meteor shower observation tables. (YP)

  8. Practical Meteor Stream Forecasting

    NASA Technical Reports Server (NTRS)

    Cooke, William J.; Suggs, Robert M.

    2003-01-01

    Inspired by the recent Leonid meteor storms, researchers have made great strides in our ability to predict enhanced meteor activity. However, the necessary calibration of the meteor stream models with Earth-based ZHRs (Zenith Hourly Rates) has placed emphasis on the terran observer and meteor activity predictions are published in such a manner to reflect this emphasis. As a consequence, many predictions are often unusable by the satellite community, which has the most at stake and the greatest interest in meteor forecasting. This paper suggests that stream modelers need to pay more attention to the needs of this community and publish not just durations and times of maxima for Earth, but everything needed to characterize the meteor stream in and out of the plane of the ecliptic, which, at a minimum, consists of the location of maximum stream density (ZHR) and the functional form of the density decay with distance from this point. It is also suggested that some of the terminology associated with meteor showers may need to be more strictly defined in order to eliminate the perception of crying wolf by meteor scientists. An outburst is especially problematic, as it usually denotes an enhancement by a factor of 2 or more to researchers, but conveys the notion of a sky filled with meteors to satellite operators and the public. Experience has also taught that predicted ZHRs often lead to public disappointment, as these values vastly overestimate what is seen.

  9. Introduction to Seamount Special Section

    NASA Astrophysics Data System (ADS)

    Watts, A. B.

    1984-12-01

    This special section is the outcome of a symposium held at the Lamont-Doherty Geological Observatory November 17-19, 1982, on the origin and evolution of seamounts. The topic for the symposium arose from the realization that although there is now a wealth of new ideas on the geology, geophysics, and geochemistry of the ocean floor, the study of seamounts has been relatively neglected despite their great importance to plate tectonics. One of the most interesting features of the ocean floor is the large number of small volcanoes or seamounts. Usually, these features are circular in plan view and have a sharp summit. There has been extensive debate in the literature about the significance of the different morphological types of seamounts. A traditional view has been that flattopped seamounts (e.g., guyots) formed as a result of subaerial erosion when the volcanoes were above sea level. Seamounts covered by fringing reefs or sediments (e.g., atolls), on the other hand, are believed to have formed when the original volcanic foundation subsided below sea level.

  10. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  11. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image s plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length "streak" meteor photome&y and two-station track determination. Meteor44 has been used to analyze data from the 2001.2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  12. Major and minor element geochemistry of deep-sea sediments in the Azores Platform and southern seamount region.

    PubMed

    Palma, Carla; Oliveira, Anabela; Valença, Manuela; Cascalho, João; Pereira, Eduarda; Lillebø, Ana I; Duarte, Armando C; Pinto de Abreu, Manuel

    2013-10-15

    The Azores Platform and the Irving and Great Meteor seamounts south of the archipelago (38°N-29°N) have rarely been studied geochemically, a fact which is surprising given that they represent the south-eastern limit of region V outlined in the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). The main aim of the present work was therefore to characterise the spatial variability of major and minor elements in deep-sea sediment cores from these two regions. XRD and geochemical analyses revealed that whereas the Azores Platform sediments are composed of a mixture of biogenic and detrital volcanic material, those at the seamounts are characterised by carbonated biogenic remains. The latter sediments were found to contain very low amounts of volcanic or hydrothermal detrital material, being almost entirely comprised of CaCO3 (more than 80%).

  13. Four years of meteor spectra patrol

    NASA Technical Reports Server (NTRS)

    Harvey, G. A.

    1974-01-01

    The development of the NASA-Langley Research Center meteor spectra patrol is described in general terms. The recording of very faint meteors was made possible by three great strides in optical and photographic technology in the 1960's: (1) the availability of optical-grade fused silica at modest cost, (2) the development of large transmission gratings with high blaze efficiency, and (3) the development of a method for avoiding plate fogging due to background skylight, which consisted of using a photoelectric meteor detector which actuates the spectrograph shutter when a meteor occurs in the field. The classification scheme for meteor spectra developed by Peter M. Millman is described.

  14. Eocene and Miocene extension, meteoric fluid infiltration, and core complex formation in the Great Basin (Raft River Mountains, Utah)

    NASA Astrophysics Data System (ADS)

    Methner, Katharina; Mulch, Andreas; Teyssier, Christian; Wells, Michael L.; Cosca, Michael A.; Gottardi, Raphaël.; Gébelin, Aude; Chamberlain, C. Page

    2015-04-01

    Metamorphic core complexes (MCCs) in the North American Cordillera reflect the effects of lithospheric extension and contribute to crustal adjustments both during and after a protracted subduction history along the Pacific plate margin. While the Miocene-to-recent history of most MCCs in the Great Basin, including the Raft River-Albion-Grouse Creek MCC, is well documented, early Cenozoic tectonic fabrics are commonly severely overprinted. We present stable isotope, geochronological (40Ar/39Ar), and microstructural data from the Raft River detachment shear zone. Hydrogen isotope ratios of syntectonic white mica (δ2Hms) from mylonitic quartzite within the shear zone are very low (-90‰ to -154‰, Vienna SMOW) and result from multiphase synkinematic interaction with surface-derived fluids. 40Ar/39Ar geochronology reveals Eocene (re)crystallization of white mica with δ2Hms ≥ -154‰ in quartzite mylonite of the western segment of the detachment system. These δ2Hms values are distinctively lower than in localities farther east (δ2Hms ≥ -125‰), where 40Ar/39Ar geochronological data indicate Miocene (18-15 Ma) extensional shearing and mylonitic fabric formation. These data indicate that very low δ2H surface-derived fluids penetrated the brittle-ductile transition as early as the mid-Eocene during a first phase of exhumation along a detachment rooted to the east. In the eastern part of the core complex, prominent top-to-the-east ductile shearing, mid-Miocene 40Ar/39Ar ages, and higher δ2H values of recrystallized white mica, indicate Miocene structural and isotopic overprinting of Eocene fabrics.

  15. The history of meteors and meteor showers

    NASA Astrophysics Data System (ADS)

    Hughes, David W.

    The history of meteors and meteor showers can effectively start with the work of Edmond Halley who overcome the Aristotelean view of meteors as being an upper atmospheric phenomenon and introduced their extraterrestrial nature. Halley also estimated their height and velocity. The observations of the Leonids in 1799, 1833 and 1866 established meteoroids as cometary debris. Two red herrings were caught — fixed radiants and hyperbolic velocities. But the 1890 to 1950 period with two-station meteor photography, meteor spectroscopy and the radar detection of meteors saw the subject well established.

  16. Meteor trajectory estimation from radio meteor observations

    NASA Astrophysics Data System (ADS)

    Kákona, J.

    2016-01-01

    Radio meteor observation techniques are generally accepted as meteor counting methods useful mainly for meteor flux detection. Due to the technical progress in radio engineering and electronics a construction of a radio meteor detection network with software defined receivers has become possible. These receivers could be precisely time synchronized and could obtain data which provide us with more information than just the meteor count. We present a technique which is able to compute a meteor trajectory from the data recorded by multiple radio stations.

  17. Can seamounts provide a good habitat for polychaete annelids? Example of the northeastern Atlantic seamounts

    NASA Astrophysics Data System (ADS)

    Surugiu, Victor; Dauvin, Jean-Claude; Gillet, Patrick; Ruellet, Thierry

    2008-11-01

    Two seamount groups in the northeastern Atlantic were investigated during the 1980s and 1990s: the first was located along the Iberian and African coasts (Galicia, to the north of Portugal; and the Ampere, Gorringe, Josephine and Seine banks near the Madeira-Canary Islands) and the second was located offshore of the southern part of the Azores Islands, included the Atlantis, Hyeres, Irving, Meteor and Plato banks. Among the invertebrates, Annelida, specifically Polychaeta, were studied as surrogates for the biogeographical relationship between coastal and mid-oceanic seamounts in the northeastern Atlantic and the fauna in these areas. The dominant families were Onuphidae (27.46%), Syllidae (18.23%), Eunicidae (15.65%), Amphinomidae (11.45%) and Nereididae (5.61%), representing 78.4% of the total fauna. Data analyses clearly distinguished two seamount groups, one for coastal seamounts and the other offshore. Although the species distinguished and the family composition at the sampled sites were different (i.e., most diversified at the Josephine site and most impoverished at the Irving site), no coastal/offshore faunal impoverishment gradient could be identified. Thus, it seems that seamount environments do not favour any relationship between planktotrophic development and the direct development of polychaetes. Though the number of apparent endemic species was low (<7%), it remained in keeping with other invertebrate groups. Still, while seamounts may well encourage oceanic biodiversity in some zoological groups, this was clearly not the case for the polychaetes. We offer two explanations for this paradox: pelagic productivity and local environmental conditions.

  18. Meteor Beliefs Project: ``Year of Meteors''

    NASA Astrophysics Data System (ADS)

    McBeath, Alastair; Drobnock, George J.; Gheorghe, Andrei Dorian

    2011-10-01

    We present a discussion linking ideas from a modern music album by Laura Veirs back to a turbulent time in American history 150 years ago, which inspired poet Walt Whitman to compose his poem "Year of Meteors", and the meteor beliefs of the period around 1859-1860, when collection of facts was giving way to analyses and theoretical explanations in meteor science.

  19. The Meteor Meter.

    ERIC Educational Resources Information Center

    Eggensperger, Martin B.

    2000-01-01

    Introduces the Meteor Scatter Project (MSP) in which high school students build an automated meteor observatory and learn to monitor meteor activity. Involves students in activities such as radio frequency survey, antenna design, antenna construction, manual meteor counts, and computer board configuration and installation. (YDS)

  20. Abundance of litter on Condor seamount (Azores, Portugal, Northeast Atlantic)

    NASA Astrophysics Data System (ADS)

    Pham, C. K.; Gomes-Pereira, J. N.; Isidro, E. J.; Santos, R. S.; Morato, T.

    2013-12-01

    Marine litter is an emerging problem for the world's ocean health but little is known on its distribution and abundance on seamounts and how it affects deep-sea ecosystems. The scientific underwater laboratory set up on Condor seamount offered an ideal case study for the first documentation of litter distribution on a shallow seamount with historical fishing. A total of 48 video transects deployed on the summit (n=45) and the northern flank (n=3) covered an area of 0.031 and 0.025km2, respectively, revealing 55 litter items. Litter density on the summit was 1439 litter items km-2, whilst on the deeper northern flank, estimates indicate densities of 397 litter items km-2. Lost fishing line was the dominant litter item encountered on both areas (73% of total litter on the summit and 50% on northern flank), all being entirely or partly entangled in the locally abundant gorgonians Dentomuricea cf. meteor and Viminella flagellum. Other items included lost weights, anchors and glass bottles. The predominance of lost fishing gear identifies the source of litter on Condor seamount as exclusively ocean-based and related to fishing activities. Abundance of litter on the Condor seamount was much lower than that reported from other locations closer to populated areas.

  1. Quadrantid Meteor, 2013

    NASA Video Gallery

    An allsky camera in New Mexico captured a brief video of this Quadrantid fireball meteor on Jan. 3, 2013 at 2:04 a.m. EST. The Quadrantid meteor shower occurs each January and derives its name from...

  2. Catalogue of representative meteor spectra

    NASA Astrophysics Data System (ADS)

    Vojáček, V.; Borovička, J.; Koten, P.; Spurný, P.; Štork, R.

    2016-01-01

    We present a library of low-resolution meteor spectra that includes sporadic meteors, members of minor meteor showers, and major meteor showers. These meteors are in the magnitude range from +2 to -3, corresponding to meteoroid sizes from 1 mm to10 mm. This catalogue is available online at the CDS for those interested in video meteor spectra.

  3. Radio Observations of Meteors.

    PubMed

    Millman, P M

    1954-08-27

    To summarize, we find that the radio technique of meteor observation enables us to extend the systematic recording of meteor rates down to the 9th or 10th magnitude; to determine satisfactory heights and velocities on a scale previously impossible; to calculate the orbits of meteor showers and individual meteors, in particular those that appear only in the daytime; and to study wind drift and fine structure in the ionosphere. The radio observations have quite definitely indicated that down to the 9th magnitude, corresponding to particles approximately 1 mm in diameter, meteors are members of the solar system and do not come from interstellar space.

  4. Precise Orbit Determination of Meteors by HPLA Radar and the MU Radar Meteor Head Echo Database

    NASA Astrophysics Data System (ADS)

    Nakamura, Takuji; Yamamoto, Mamoru; Tanaka, Yoshi; Kero, Johan; Szasz, Csilla; Watanabe, Juniichi; Abe, Shinsuke; Kastinen, Daniel

    Mass influx from the space into the terrestrial atmosphere is mainly caused by meteors. Meteors delivers various elements into the atmosphere, but the meteoric dust particles are also of great importance in the terrestrial atmosphere, as they act as nucleus for condensation and clouds and affect various atmospheric phenomena both in physical and chemical aspects. Thus, to investigate the meteor flux, orbits and their interactions in the upper atmosphere is very important but at the same time the method of investigation is limited, especially for the precise measurements High power large aperture (HPLA) radar observation is a recent technique to provide useful information on meteor influx and orbits, as well as interactions with the atmosphere. The recent development of the technique carried out using the middle and upper atmosphere radar (MU radar) of Kyoto University at Shigaraki (34.9N, 136.1S), which is a large atmospheric VHF radar with 46.5 MHz frequency, 1 MW output transmission power and 8330 m2 aperture array antenna, has established very precise orbit observations from meteor head echoes. Since 2009, orbital data of about 120,000 meteors have been collected. An open database (MU radar meteor head echo database: MURMHED) for research and education is now being created. In this study, we present the physical quantities and precisions obtained from the MU radar meteor head echo observations and the details of the open database.

  5. Rare Double Quadrantid Meteor Sighting

    NASA Video Gallery

    The wide-field meteor camera at NASA's Marshall Space Flight Center recorded these two simultaneous Quadrantid meteors on Jan. 4 at approximately 5 a.m. EST. Moving at 92,000 mph, the meteors flash...

  6. Meteor Beliefs Project: Introduction

    NASA Astrophysics Data System (ADS)

    McBeath, A.; Gheorghe, A. D.

    2003-05-01

    A new project to investigate beliefs in meteors and meteoric phenomena in past and present times using chiefly folklore, mythology, prose and poetic literature, is described. Some initial examples are given, along with a bibliography of relevant items already in print in IMO publications.

  7. The Eratosthenes Seamount - Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Ehrhardt, A.; Schnabel, M.; Damm, V.

    2012-04-01

    The Eratosthenes Seamount forms a prominent landmark in the Eastern Mediterranean. It is located south of Cyprus with the Levantine Basin on its eastern side, the Herodotus Basin on its western side and the Nile Cone south of the seamount. The Eratosthenes Seamount rises up to 750 m below sea surface and is about 1200 m higher than the surrounding seafloor of the Levantine Basin and the Nile Cone sediments. The Eratosthenes Seamount is considered as a continental fragment of the former African-Nubian Plate that was rifted to its present position relative to Africa during the formation of the Tethyan Ocean. In 2010 a detailed geophysical survey was carried out in the area of the Eratosthenes Seamount by the Federal Institute for Geosciences and Natural Resources of Germany including multichannel seismic (MCS), refraction seismics, magnetic, gravity and magnetotelluric data acquisition. First results show a highly deformed seamount, with a plateau-like top that is impacted by west-east trending graben formation. The slopes of the seamount are eroded showing deep incised ripple patterns and recent submarine landslides. The Eratosthenes Seamount produces also a prominent magnetic and gravity anomaly, both supporting its uniqueness in the area of the Eastern Mediterranean. Velocity information by refraction seismic modeling, as well as the models of the magnetic and gravity data show evidence for a volcanic core of the seamount with carbonate layers on top of the volcanic core. The slopes of the seamount terminate against a conspicuous rim-like escarpment that forms in addition the northern and western termination of the Messinian Evaporites in the study area. The MCS and refraction seismic data show a very deep Levantine Basin with maximum acoustic basement depths of 12 to 14 km very close to the slope of the Eratosthenes Seamount. The deepest sediments resolved by the MCS data are of Lower Cretaceous to Jurassic age. The refraction seismic model shows a 14 km thick

  8. High-Resolution Geomorphometry of Seamounts of the Young Walvis Ridge Guyot Province

    NASA Astrophysics Data System (ADS)

    Schnur, S. R.; Koppers, A. A.

    2012-12-01

    In February and March 2012, cruise MV1203 surveyed and dredged seamounts at the young end of the Walvis Ridge hotspot trail in the South Atlantic. The scientific goals were to better understand the hotspot origins of the Walvis Ridge by collecting rock samples for high-precision 40Ar/39Ar geochronology and by investigating the relationship between seamount morphology and different mechanisms of intra-plate volcanism. The area had until now been only sparsely-sampled, and most of the seamounts had never been mapped with multibeam. Here we present a geomorphometric analysis of edifice size and shape parameters from 74 seamounts of the young Walvis Ridge guyot province. The base data for each seamount consists of Simrad EM122 multibeam bathymetry combined with bathymetry from the SRTM30 PLUS compilation (V7.0: Becker et al., 2009; Sandwell and Smith, 2009), gridded at 180 m resolution. Multibeam coverage of individual seamounts ranges from 100% for small seamounts to 15% for large seamounts, with most seamounts having at least 50% coverage. Most of this data focuses on seamount flanks rather than flat guyot tops, covering the areas of greatest topographic variability even for seamounts with relatively low multibeam coverage. For each seamount we quantify edifice height, perimeter, volume, elongation, azimuth, irregularity and distance to nearest neighbor. These variables are compared to the age of the underlying crust, distance to the Mid-Atlantic Ridge and distance from the Etendeka flood basalts of Namibia, which are thought to signal the initial stages of hotspot volcanism at the old end of the chain. Additionally we assess how the addition of high resolution data affects these geomorphologic parameters. We will present an overview of the cruise outcomes as well as highlight unusual features observed in the new bathymetry and backscatter data. The cruise data suggest that the young Walvis Ridge guyot province holds great potential for further exploration and

  9. Global distribution of seamounts from Seasat profiles

    NASA Technical Reports Server (NTRS)

    Craig, Claire H.; Sandwell, David T.

    1988-01-01

    A new measurement techique based on a model of a Gaussian seamount loading a thin elastic lithosphere was developed to analyze seamounts that, until then, were not surveyed or seamounts with poor bathymetric coverage. The model predicts that the seamount diameter is equal to the peak-to-trough distance along the vertical deflection profile and that the flexural diameter of a seamount is related to the age of the lithosphere when the seamount formed. This model also suggests that these two measurements are relatively insensitive to the cross-track location from the seamount. These model predictions were confirmed using Seasat altimeter profiles crossing 14 surveyed seamounts in the Pacific. The analysis of the seamount distribution indicated considerable variations in population density and type across the oceans. Most notable among them are the absence of seamounts in the Atlantic, variations in population density across large fracture zones in the Pacific, and the prevalence of small signatures in the Indian Ocean.

  10. Meteor Researches at Khnure

    NASA Astrophysics Data System (ADS)

    Kolomiyets, Svitlana V.; Voloshchuk, Yuri I.; Kashcheyev, Boris L.; Slipchenko, Nikolay I.

    The Scientific Educational Center of Radioengineering of the Kharkiv National University of Radioelectronics (KHNURE: ) is one of the oldest radar meteor centers which was founded by B. L. Kashcheyev in 1958. The first automatic meteor radar system in Ukraine “MARS” is connected with our University. There are long-term observational series of meteor rates and orbital data in the Center. Fields of the KHNURE researches are: a structure of meteor showers a determination of meteoroid orbits an influx of cosmic rubbish in the Earth atmosphere search of parental bodies of meteoroids a statistic analysis of measurement results of radiometeors an estimation of errors of meteor radar measurements a search for real hyperbolic orbits and interstellar meteoroids. KHNURE disposes a unique electronic orbital catalogue. This catalogue contains the primary information velocities radiants and orbits of nearly 250000 radiometeoroids with masses from 0.001 to 0.000001 g. The “MARS” registered these data during observations of 1972 1978. From these data 5160 meteor streams are singled out. New classification of streams is made in view of their structure. The study of meteor stream orbits from the KHNURE data bank allow to predict orbits of a big number of undiscovered “dangerous” NEOs

  11. Meteor researches at KHNURE

    NASA Astrophysics Data System (ADS)

    Kolomiyets, Svitlana V.; Voloshchuk, Yuri I.; Kashcheyev, Boris L.; Slipchenko, Nikolay I.

    2005-01-01

    The Scientific Educational Center of Radioengineering of the Kharkiv National University of Radioelectronics (KHNURE: ) is one of the oldest radar meteor centers which was founded by B. L. Kashcheyev in 1958. The first automatic meteor radar system in Ukraine “MARS” is connected with our University. There are long-term observational series of meteor rates and orbital data in the Center. Fields of the KHNURE researches are: a structure of meteor showers a determination of meteoroid orbits an influx of cosmic rubbish in the Earth atmosphere search of parental bodies of meteoroids a statistic analysis of measurement results of radiometeors an estimation of errors of meteor radar measurements a search for real hyperbolic orbits and interstellar meteoroids. KHNURE disposes a unique electronic orbital catalogue. This catalogue contains the primary information velocities radiants and orbits of nearly 250000 radiometeoroids with masses from 0.001 to 0.000001 g. The “MARS” registered these data during observations of 1972 1978. From these data 5160 meteor streams are singled out. New classification of streams is made in view of their structure. The study of meteor stream orbits from the KHNURE data bank allow to predict orbits of a big number of undiscovered “dangerous” NEOs.

  12. Age progressive volcanism in the Tasmantid Seamounts

    NASA Astrophysics Data System (ADS)

    McDougall, Ian; Duncan, Robert A.

    1988-07-01

    The Tasmantid Seamounts comprise a northerly trending linear chain of submarine volcanoes that extend over more than 1300 km in the middle of the Tasman Basin, located to the east of the Australian continental margin. The volcanoes are situated upon deep oceanic crust of Late Cretaceous/Early Cenozoic age. Several of the volcanoes were built from sea floor depths of more than 4000 m to above sea level, and were then eroded to flat-topped mountains which have subsided to depths as great as 400 m. Basalt samples dredged from Gascoyne, Taupo, Derwent Hunter, Britannia and Queensland Seamounts have been dated by the K-Ar and 40Ar/ 39Ar methods, yielding results in the range 24 to 6.4 Ma, Early to Late Miocene. A progressive younging of the volcanism southward along the seamount chain at an average rate of 67 ± 5mm/year is indicated. The predicted present position of the volcanic focus is at 40.4°S latitude, and between 155° and 156°E longitude, virtually coincident with the epicentre of a recent large earthquake. These results provide strong evidence that the Tasmantid Seamounts represent a hotspot track, effectively recording motion of the Australian plate across the sublithospheric mantle source region for the volcanism. Comparison with results from hotspot traces on the same plate and on the African plate further demonstrate that these hotspots provide a useful frame of reference for plate motions, and that relative movement between individual hotspots must be less than about 5 mm/year.

  13. Minor meteor shower activity

    NASA Astrophysics Data System (ADS)

    Rendtel, J.

    2016-01-01

    Video meteor observations provide us with data to analyze structures in minor meteor showers or weak features in flux profiles. Samples obtained independently by other techniques allow to calibrate the data sets and to improve the confidence of results as demonstrated with a few results. Both, the confirmation of events predicted by model calculation and the input of observational data to improve the modelling results may help to better understand meteoroid stream evolution processes. Furthermore, calibrated data series can be used for studies of the long-term evolution of meteor shower activity.

  14. Influence of the meteoric stream on weather conditions: preliminary consideration

    NASA Astrophysics Data System (ADS)

    Granitskii, Lev V.; Borisevich, A. N.

    2000-12-01

    By the some estimation, about 150 tons of the meteoric matter are fall on the Earth every day. Some researchers note coincidence of the periods of activity of the most powerful meteoric stream with the periods of intensive falling of atmospheric precipitation. The unique meteoric stream Leonids represents the great interest as an example of possible correlation between meteors and power precipitation. The comet produced this stream is well known as Tempel-Tuttl comet, its orbital period is 33.3 years. With the same periodicity, the sharp strengthening of activity of a stream, which is called meteoric shower, is observed. Such meteoric stream during a night could cover the average monthly norm of fall of meteoric bodies at once in tens time. The analysis of meteorological data shows, that the winters of 1933, 1966, 1998 and 1999 years of a maximum Leonids activity are characterized by huge amount of snow. These anomalies have resulted in disasters in some of region. Under our suggestions, the anomaly rate of falling precipitation can be explained by the meteoric dust, which plays the role of the nucleuses of condensation. Thus, taking in to account the dada of regular meteoric stream, it's possible to make long term weather forecasting with the more preciseness.

  15. The Southern Argentine Agile Meteor Radar (SAAMER)

    NASA Astrophysics Data System (ADS)

    Janches, Diego

    2014-11-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53 S) in May 2008. SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large number of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars. In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions. The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source, of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables detailed study of showers at high southern latitudes (e.g July Phoenicids or Puppids complex). Finally, SAAMER is ideal for the deployment of complementary instrumentation in both, permanent

  16. Resolving Seamounts in Satellite Altimetry

    NASA Astrophysics Data System (ADS)

    Marks, K. M.; Smith, W. H.

    2006-12-01

    We have examined three factors influencing the use of satellite altimeter data to map seamounts and guyots in the deep ocean: (1) the resolution of seamount and guyot gravity anomalies by altimetry; (2) the non-linearity of the relationship between gravity and bathymetry; and (3) the homogeneity of the mass density within the seamount or guyot. When altimeter data are used to model the marine gravity anomaly field the result may have limited resolution due to noise levels in the altimeter data, track spacing of the satellite profiles, inclination angles of the orbits, and filters used to combine and interpolate the data (Sandwell and Smith, JGR, 1997). We compared the peak-to-trough amplitude of gravity anomalies in Sandwell and Smith`'s version 15.1 field to peak-to-trough amplitudes measured by gravimeters on board ships. The satellite gravity field amplitudes match ship measurements well over seamounts and guyots having volumes exceeding ~2000 km3. Over smaller volume seamounts, where the anomalies have most of their power at quite short wavelengths, the satellite field under-estimates the anomaly amplitude. If less filtering could be done, or a new mission with a lower noise level were flown, more of the anomalies associated with small seamounts might be resolved. Smith and Sandwell (Science, 1997) predicted seafloor topography from altimetric gravity assuming that the density of seafloor topography is nearly constant over ~100 km distances, and that the relationship between gravity and topography may be approximated by a liner filter over those distances. In fact, the true theoretical relationship is non-linear (Parker, Geophys. J. R. astr. Soc, 1972); it can be expressed as an N-th order expansion, with the N=1 term representing a linear filter and the N>1 terms accounting for higher-order corrections. We find that N=2 is a sufficient approximation at both seamounts and guyots. Constant density models of large volume guyots do not fit the observed gravity

  17. Photoacoustic Sounds from Meteors

    PubMed Central

    Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, GiGi; Spurný, Pavel

    2017-01-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with −11 to −13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that −12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs. PMID:28145486

  18. Persistent Leonid Meteor Trails

    NASA Astrophysics Data System (ADS)

    Drummond, J. D.; Milster, S. P.; Grime, B. W.; Gardner, C. S.; Liu, A. Z.; Chu, X.; Kelley, M. C.; Kruschwitz, C. A.; Kane, T. J.

    2000-10-01

    In 1998 and 1999 a campaign was conducted to study the lingering trails left by (brighter than -1.5 mag) Leonid meteors over the Starfire Optical Range near Albuquerque, NM, a facility owned by the Directed Energy Directorate of the Air Force Research Laboratory. Although not unique to the Leonids, lingering trails are characteristic of the brighter members of this shower, even in non-storm years. They are self-luminous from unknown chemiluminscent reactions involving both atmospheric and cometary species. A sodium lidar was used to probe the aftermath of several meteors, some of which left trails visible for more than 20 minutes. CCD images have been analyzed for four trails. The classical explanation of the double line appearance of many trails as shell burning in an optically thin cylinder is shown to be invalid. Surface brightnesses and line emission rates have been derived and indicate that the trails are overbright compared to non-Leonids by orders of magnitude, pointing perhaps to a compositional difference between lingering trails of Leonid and non-Leonid meteors. Because the atmospheric trajectory of the parent meteor is known, the winds and parameters of a gravity wave between 90-100 km above the Earth have been deduced from a single image taken 1-2 minutes after the meteor, or from a series of images. A five degree wide video camera was used to record the evolution of several trails, and a highlight video will be shown of this fascinating and mysterious phenomenon.

  19. Photoacoustic Sounds from Meteors

    NASA Astrophysics Data System (ADS)

    Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, Gigi; Spurný, Pavel

    2017-02-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with ‑11 to ‑13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that ‑12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.

  20. Photoacoustic sounds from meteors

    DOE PAGES

    Spalding, Richard; Tencer, John; Sweatt, William; ...

    2017-02-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with –11 to –13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally.more » Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that –12 brightness meteors can generate audible sound at ~25 dB SPL. As a result, the photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.« less

  1. Meteor Beliefs Project: meteors in the poems of John Donne

    NASA Astrophysics Data System (ADS)

    McBeath, A.; Gheorghe, A. D.

    2004-07-01

    An examination of the uses of meteor imagery in the poems of Englishman John Donne (1572-1631) is made, revealing a set of beliefs reflecting the period when ideas about astronomy, including meteors, were beginning to undergo radical change.

  2. Watching meteors on Triton

    NASA Astrophysics Data System (ADS)

    Pesnell, W. Dean; Grebowsky, J. M.; Weisman, Andrew L.

    2004-06-01

    The thin atmosphere of Neptune's moon Triton is dense enough to ablate micrometeoroids as they pass through. A combination of Triton's orbital velocity around Neptune and its orbital velocity around the Sun gives a maximum meteoroid impact velocity of approximately 19 km s -1, sufficient to heat the micrometeoroids to visibility as they enter. The ablation profiles of icy and stony micrometeoroids were calculated, along with the estimated brightness of the meteors. In contrast to the terrestrial case, visible meteors would extend very close to the surface of Triton. In addition, the variation in the meteoroid impact velocity as Triton orbits Neptune produces a large variation in the brightness of meteors with orbital phase, a unique Solar System phenomenon.

  3. An unusual meteor spectrum

    NASA Technical Reports Server (NTRS)

    Cook, A. F.; Hemenway, C. L.; Millman, P. M.; Swider, A.

    1973-01-01

    An extraordinary spectrum of a meteor at a velocity of about 18.5 + or - 1.0 km/s was observed with an image orthicon camera. The radiant of the meteor was at an altitude of about 49 deg. It was first seen showing a yellow red continuous spectrum alone at a height of 137 + or - 8 km which is ascribed to the first positive group of nitrogen bands. After the meteor had descended to 116 + or - 6 km above sea level it brightened rapidly from its previous threshold brightness into a uniform continuum, the D-line of neutral sodium appeared, and at height 105 + or - 5 km all the other lines of the spectrum also appeared. The continuum remained dominant to the end. Water of hydration and entrained carbon flakes of characteristic dimension about 0.2 micron or less are proposed as constituents of the meteoroid to explain these phenomena.

  4. METEORIC-HYDROTHERMAL SYSTEMS.

    USGS Publications Warehouse

    Criss, Robert E.; Taylor, Hugh P.

    1986-01-01

    This paper summarizes the salient characteristics of meteoric-hydrothermal systems, emphasing the isotopic systematics. Discussions of permeable-medium fluid dynamics and the geology and geochemistry of modern geothermal systems are also provided, because they are essential to any understanding of hydrothermal circulation. The main focus of the paper is on regions of ancient meteoric-hydrothermal activity, which give us information about the presently inaccessible, deep-level parts of modern geothermal systems. It is shown oxygen and hydrogen isotopes provide a powerful method to discover and map fossil hydrothermal systems and to investigate diverse associated aspects of rock alteration and ore deposition.

  5. Martian Meteor Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    20 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fairly young meteor impact crater on Mars that is about the same size ( 1 kilometer; 0.62 miles) as the famous Meteor Crater in northern Arizona, U.S.A. Like the Arizona crater, boulders of ejected bedrock can be seen on the crater's ejecta blanket and in the crater itself. This crater is located in the Aethiopis region of Mars near 4.7oN, 224.1oW. Sunlight illuminates the scene from the lower left.

  6. Age of Kōko Seamount, Emperor Seamount chain

    USGS Publications Warehouse

    Clague, David A.; Dalrymple, G. Brent

    1973-01-01

    KAr ages obtained by the conventional isotope-dilution and the 40Ar/39Ar techniques on two sanidine trachytes, four basalts, and a phonolite dredged from the top of Ko¯ko Seamount, 300 km north of the Hawaiian-Emperor bend, show that the seamount is 46.4 ± 1.1 my old. These data indicate that the volcanoes in the Hawaiian-Emperor chain continue to increase in age to the west and north beyond Midway Atoll, as predicted by the melting-spot hypothesis for the origin of the chain, and that the rate of volcanic migration along the chain was nonlinear between the time of formation of the island of Hawaii and Ko¯ko Seamount.

  7. Discovery of Leonid Meteoric Cloud

    DTIC Science & Technology

    2007-11-02

    as a local enhancement in sky brightness during the meteor shower in 1998. The radius of the trail, deduced from the spatial extent of the cloud, is...A meteoric cloud is a faint glow of sunlight scattered by the small meteoroids in the trail along a parent comets orbit. Here we report the first...detection of the meteoric cloud associated with the Leonid meteor stream. Our photometric observations, performed on Mauna Kea, Hawaii, reveal the cloud

  8. Asteroids, Comets, Meteors 1991

    NASA Technical Reports Server (NTRS)

    Harris, Alan W. (Editor); Bowell, Edward (Editor)

    1992-01-01

    Papers from the conference are presented and cover the following topics with respect to asteroids, comets, and/or meteors: interplanetary dust, cometary atmospheres, atmospheric composition, comet tails, astronomical photometry, chemical composition, meteoroid showers, cometary nuclei, orbital resonance, orbital mechanics, emission spectra, radio astronomy, astronomical spectroscopy, photodissociation, micrometeoroids, cosmochemistry, and interstellar chemistry.

  9. Video Meteor Fluxes

    NASA Technical Reports Server (NTRS)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  10. Studies of Transient Meteor Activity

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter M. M.

    2002-01-01

    Meteoroids bombard Earth's atmosphere daily, but occasionally meteor rates increase to unusual high levels when Earth crosses the relatively fresh ejecta of comets. These transient events in meteor activity provide clues about the whereabouts of Earth-threatening long-period comets, the mechanisms of large-grain dust ejection from comets, and the particle composition and size distribution of the cometary ejecta. Observations of these transient events provide important insight in natural processes that determine the large grain dust environment of comets, in natural phenomena that were prevalent during the time of the origin of life, and in processes that determine the hazard of civilizations to large impacts and of man-made satellites to the periodic blizzard of small meteoroids. In this proposal, three tasks form a coherent program aimed at elucidating various aspects of meteor outbursts, with special reference to planetary astronomy and astrobiology. Task 1 was a ground-based effort to observe periods of transient meteor activity. This includes: (1) stereoscopic imaging of meteors during transient meteor events for measurements of particle size distribution, meteoroid orbital dispersions and fluxes; and (2) technical support for Global-MS-Net, a network of amateur-operated automatic counting stations for meteor reflections from commercial VHF radio and TV broadcasting stations, keeping a 24h vigil on the level of meteor activity for the detection of new meteor streams. Task 2 consisted of ground-based and satellite born spectroscopic observations of meteors and meteor trains during transient meteor events for measurements of elemental composition, the presence of organic matter in the meteoroids, and products generated by the interaction of the meteoroid with the atmosphere. Task 3 was an airborne effort to explore the 2000 Leonid meteor outbursts, which are anticipated to be the most significant of transient meteor activity events in the remainder of the

  11. Geochemical fluxes related to alteration of a subaerially exposed seamount: Nintoku seamount, ODP Leg 197, Site 1205

    NASA Astrophysics Data System (ADS)

    RéVillon, Sidonie; Teagle, Damon A. H.; Boulvais, Philippe; Shafer, John; Neal, Clive R.

    2007-02-01

    Hole 1205A was drilled on Nintoku Seamount, which lies in the midportion of the Emperor Seamount Chain. This seamount was emergent ˜56 Myr ago but was submerged by 54 Ma, so the lavas have endured weathering in both subaerial and submarine environments. We have studied the petrology, mineralogy, and geochemistry of intercalated altered basalts, breccias, and soil samples recovered at Hole 1205A to quantify the chemical exchanges between the seamount and seawater and/or meteoric fluids. The secondary mineralogy is relatively uniform throughout the section and comprises smectite, Fe-oxyhydroxides, iddingsite, and Ca-carbonates. Soils are composed of variably altered basaltic clasts in a matrix of kaolinite, smectite, and vermiculite with minor goethite, hematite, and magnetite. Throughout the basement section, altered basalts, breccias, and soils are depleted in Si, Mg, Ca, Na, Sr, Rb, and Ba and enriched in Fe. Fe3+/FeT (up to ˜1), δ18O (up to ˜+20‰), and 87Sr/86Sr ratios are strongly elevated relative to primary igneous values. Differences in the 87Sr/86Sr ratios define an Upper Alteration Zone with 87Sr/86Sr close to 56 Ma seawater (˜0.7077) from a Lower Alteration Zone where 87Sr/86Sr are less elevated (˜0.704). The Lower Alteration Zone likely reflects interaction with a subaerial oxidizing fluid at low temperature. This zone probably retained most of the original subaerial weathering signature. The Upper Alteration Zone was altered through circulation of large quantities of cold oxidizing seawater that partially overprinted the subaerial weathering chemical characteristics. Altered samples were compared to estimated protolith compositions to calculate chemical gains and losses. Global chemical fluxes are calculated for the entire basement section using different lithological proportions models and different rates of oceanic island emplacement. Although the global construction rate of ocean islands is small compared to igneous accretion at mid

  12. Optical fluxes and meteor properties of the camelopardalid meteor shower

    NASA Astrophysics Data System (ADS)

    Campbell-Brown, M. D.; Blaauw, R.; Kingery, A.

    2016-10-01

    Observations of the Camelopardalid meteor shower in May 2014 were obtained with six different sets of cameras, with limiting meteor magnitudes varying from -2M to +7M. Shower fluxes were calculated for each of the systems, from which the mass index of the shower was found to be 2.17 ± 0.04. Faint meteors in the shower were found to be stronger than average, ablating at lower altitudes than meteors at the same speed recorded with the same system, while the brightest meteors had higher ablation heights and were therefore weaker than typical meteors. These findings can be explained if large Camelopardalids are weak agglomerations of more refractory grains, which are easily disrupted in space and keep the shower supplied with small material and depleted in large material.

  13. Zhamanshin meteor crater

    NASA Technical Reports Server (NTRS)

    Florenskiy, P. V.; Dabizha, A. I.

    1987-01-01

    A historical survey and geographic, geologic and geophysical characteristics, the results of many years of study of the Zhamanshin meteor crater in the Northern Aral region, are reported. From this data the likely initial configuration and cause of formation of the crater are reconstructed. Petrographic and mineralogical analyses are given of the brecciated and remelted rocks, of the zhamanshinites and irgizite tektites in particular. The impact melting, dispersion and quenching processes resulting in tektite formation are discussed.

  14. Meteor signature interpretation

    SciTech Connect

    Canavan, G.H.

    1997-01-01

    Meteor signatures contain information about the constituents of space debris and present potential false alarms to early warnings systems. Better models could both extract the maximum scientific information possible and reduce their danger. Accurate predictions can be produced by models of modest complexity, which can be inverted to predict the sizes, compositions, and trajectories of object from their signatures for most objects of interest and concern.

  15. Meteors in Australian Aboriginal Dreamings

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.; Norris, Ray P.

    2010-06-01

    We present a comprehensive analysis of Australian Aboriginal accounts of meteors. The data used were taken from anthropological and ethnographic literature describing oral traditions, ceremonies, and Dreamings of 97 Aboriginal groups representing all states of modern Australia. This revealed common themes in the way meteors were viewed between Aboriginal groups, focusing on supernatural events, death, omens, and war. The presence of such themes around Australia was probably due to the unpredictable nature of meteors in an otherwise well-ordered cosmos.

  16. Oceanographic aspects of the Emperor Seamounts region

    SciTech Connect

    Roden, G.I.; Taft, B.A.; Ebbesmeyer, C.C.

    1982-11-20

    Effects of the Emperor Seamount Chain on the thermohaline structure and baroclinic flow are investigated on the basis of historical hydrographic data. The amplitudes of dynamic height perturbations are 3 to 5 times larger west than east of the chain. The intensity of the thermal fronts is stronger west than east of the seamounts; near the crest of the southern seamounts, strong east-west thermohaline fronts and a strong northward baroclinic flow are observed. The Kuroshio Extension west of the seamount chain is a well-defined meandering current, the axis of which generally lies between 33/sup 0/ and 36/sup 0/N. The available data indicate that the Kuroshio Extension turns northward and then flows eastward through the gaps of the seamount chain. East of the seamounts, the Kuroshio Extension widens threefold and appears to be poorly defined.

  17. Meteor Beliefs Project: Meteoric references in Ovid's Metamorphoses

    NASA Astrophysics Data System (ADS)

    Gheorghe, A. D.; McBeath, A.

    2003-10-01

    Three sections of Ovid's Metamorphoses are examined, providing further information on meteoric beliefs in ancient Roman times. These include meteoric imagery among the portents associated with the death of Julius Caesar, which we mentioned previously from the works of William Shakespeare (McBeath and Gheorghe, 2003b).

  18. James Joule and meteors

    NASA Astrophysics Data System (ADS)

    Hughes, David W.

    1989 was the hundredth anniversary of the death of James Prescott Joule, the Prescott being his mother's family name and the Joule, rhyming with cool, originating from the Derbyshire village of Youlgreave. Joule is rightly famous for his experimental efforts to establish the law of conservation of energy, and for the fact that J, the symbol known as the mechanical equivalent of heat, is named after him. Astronomically his "light has been hidden under a bushel". James Joule had a major influence on the physics of meteors.

  19. Meteor fireball sounds identified

    NASA Technical Reports Server (NTRS)

    Keay, Colin

    1992-01-01

    Sounds heard simultaneously with the flight of large meteor fireballs are electrical in origin. Confirmation that Extra/Very Low Frequency (ELF/VLF) electromagnetic radiation is produced by the fireball was obtained by Japanese researchers. Although the generation mechanism is not fully understood, studies of the Meteorite Observation and Recovery Project (MORP) and other fireball data indicate that interaction with the atmosphere is definitely responsible and the cut-off magnitude of -9 found for sustained electrophonic sounds is supported by theory. Brief bursts of ELF/VLF radiation may accompany flares or explosions of smaller fireballs, producing transient sounds near favorably placed observers. Laboratory studies show that mundane physical objects can respond to electrical excitation and produce audible sounds. Reports of electrophonic sounds should no longer be discarded. A catalog of over 300 reports relating to electrophonic phenomena associated with meteor fireballs, aurorae, and lightning was assembled. Many other reports have been cataloged in Russian. These may assist the full solution of the similar long-standing and contentious mystery of audible auroral displays.

  20. Asteroids, Comets, Meteors 2014

    NASA Astrophysics Data System (ADS)

    Muinonen, K.; Penttilä, A.; Granvik, M.; Virkki, A.; Fedorets, G.; Wilkman, O.; Kohout, T.

    2014-08-01

    Asteroids, Comets, Meteors focuses on the research of small Solar System bodies. Small bodies are the key to understanding the formation and evolution of the Solar System, carrying signals from pre-solar times. Understanding the evolution of the Solar System helps unveil the evolution of extrasolar planetary systems. Societally, small bodies will be important future resources of minerals. The near-Earth population of small bodies continues to pose an impact hazard, whether it be small pieces of falling meteorites or larger asteroids or cometary nuclei capable of causing global environmental effects. The conference series entitled ''Asteroids, Comets, Meteors'' constitutes the leading international series in the field of small Solar System bodies. The first three conferences took place in Uppsala, Sweden in 1983, 1985, and 1989. The conference is now returning to Nordic countries after a quarter of a century. After the Uppsala conferences, the conference has taken place in Flagstaff, Arizona, U.S.A. in 1991, Belgirate, Italy in 1993, Paris, France in 1996, Ithaca, New York, U.S.A. in 1999, in Berlin, Germany in 2002, in Rio de Janeiro, Brazil in 2005, in Baltimore, Maryland, U.S.A. in 2008, and in Niigata, Japan in 2012. ACM in Helsinki, Finland in 2014 will be the 12th conference in the series.

  1. Co-rich Mn crusts from the Magellan Seamount cluster: the long journey through time

    NASA Astrophysics Data System (ADS)

    Glasby, Geoffrey P.; Ren, Xiangwen; Shi, Xuefa; Pulyaeva, Irina A.

    2007-10-01

    The Magellan seamounts began forming as large submarine shield volcanoes south of the equator during the Cretaceous. These volcanoes formed as a cluster on the small Pacific plate in a period when tectonic stress was absent. Thermal subsidence of the seafloor led to sinking of these volcanoes and the formation of guyots as the seamounts crossed the equatorial South Pacific (10-0°S) sequentially and ocean surface temperatures became too high for calcareous organisms to survive. Guyot formation was completed between about 59 and 45 Ma and the guyots became phosphatized at about 39-34 and 27-21 Ma. Ferromanganese crusts began formation as proto-crusts on the seamounts and guyots of the Magellan Seamount cluster towards the end of the Cretaceous up to 55 Ma after the formation of the seamounts themselves. The chemical composition of these crusts evolved over time in a series of steps in response to changes in global climate and ocean circulation. The great thickness of these crusts (up to 15-20 cm) reflects their very long period of growth. The high Co contents of the outer parts of the crusts are a consequence of the increasing deep circulation of the ocean and the resulting deepening of the oxygen minimum zone with time. Growth of the Co-rich Mn crusts in the Magellan Seamount cluster can be considered to be the culmination of a long journey through time.

  2. The Chelyabinsk meteor

    NASA Astrophysics Data System (ADS)

    Popova, O.; Jenniskens, P.; Shuvalov, V.; Emel'yanenko, V.; Rybnov, Y.; Kharlamov, V.; Kartashova, A.; Biryukov, E.; Khaibrakhmanov, S.

    2014-07-01

    A review is given about what was learned about the 0.5-Mt Chelyabinsk airburst of 15 February 2013 by field studies, the analysis of recovered meteorites, and numerical models of meteoroid fragmentation and airburst propagation. Previous events with comparable or larger energy in recent times include only the 0.5-Mt -sized 3 August 1963 meteor over the south Atlantic, for which only an infrasound signal was recorded, and the famous Tunguska impact of 1908. Estimates of the initial kinetic energy of the Tunguska impact range from 3 to 50 Mt, due to the lack of good observations at the time. The Chelyabinsk event is much better documented than both, and provides a unique opportunity to calibrate the different approaches used to model meteoroid entry and calculate the damaging effects of a shock wave from a large meteoroid impact. A better understanding of what happened might help future impact hazard mitigation efforts by calibrating models of what might happen under somewhat different circumstances. The initial kinetic energy is estimated from infrasonic signals and the fireball's lightcurve, as well as the extent of the glass damage on the ground. Analysis of video observations of the fireball and the shadow movements provided an impact trajectory and a record of the meteor lightcurve, which describes how that energy was deposited in the atmosphere. Ablation and fragmentation scenarios determine the success of attempts to reproduce the observed meteor lightcurve and deceleration profile by numerical modeling. There was almost no deceleration until peak brightness. Meteoroid fragmentation occurred in different forms, some part of the initial mass broke in well separated fragments, the surviving fragments falling on the ground as meteorites. The specific conditions during energy deposition determined the fraction of surviving mass. The extent of the glass damage was mapped by visiting over 50 villages in the area. A number of numerical simulations were conducted that

  3. Antarctic meteor observations using the Davis MST and meteor radars

    NASA Astrophysics Data System (ADS)

    Holdsworth, David A.; Murphy, Damian J.; Reid, Iain M.; Morris, Ray J.

    2008-07-01

    This paper presents the meteor observations obtained using two radars installed at Davis (68.6°S, 78.0°E), Antarctica. The Davis MST radar was installed primarily for observation of polar mesosphere summer echoes, with additional transmit and receive antennas installed to allow all-sky interferometric meteor radar observations. The Davis meteor radar performs dedicated all-sky interferometric meteor radar observations. The annual count rate variation for both radars peaks in mid-summer and minimizes in early Spring. The height distribution shows significant annual variation, with minimum (maximum) peak heights and maximum (minimum) height widths in early Spring (mid-summer). Although the meteor radar count rate and height distribution variations are consistent with a similar frequency meteor radar operating at Andenes (69.3°N), the peak heights show a much larger variation than at Andenes, while the count rate maximum-to-minimum ratios show a much smaller variation. Investigation of the effects of the temporal sampling parameters suggests that these differences are consistent with the different temporal sampling strategies used by the Davis and Andenes meteor radars. The new radiant mapping procedure of [Jones, J., Jones, W., Meteor radiant activity mapping using single-station radar observations, Mon. Not. R. Astron. Soc., 367(3), 1050-1056, doi: 10.1111/j.1365-2966.2006.10025.x, 2006] is investigated. The technique is used to detect the Southern delta-Aquarid meteor shower, and a previously unknown weak shower. Meteoroid speeds obtained using the Fresnel transform are presented. The diurnal, annual, and height variation of meteoroid speeds are presented, with the results found to be consistent with those obtained using specular meteor radars. Meteoroid speed estimates for echoes identified as Southern delta-Aquarid and Sextantid meteor candidates show good agreement with the theoretical pre-atmospheric speeds of these showers (41 km s -1 and 32 km s -1

  4. JEM-EUSO: Meteor and nuclearite observations

    NASA Astrophysics Data System (ADS)

    Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Arai, Y.; Asano, K.; Ave Pernas, M.; Baragatti, P.; Barrillon, P.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellinic, G.; Catalano, C.; Catalano, G.; Cellino, A.; Chikawa, M.; Christl, M. J.; Cline, D.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Dell'Oro, A.; De Simone, N.; Di Martino, M.; Distratis, G.; Dulucq, F.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Franceschi, A.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; Garipov, G.; Geary, J.; Gelmini, G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, J.-S.; Kim, S.-W.; Kim, S.-W.; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Maravilla, D.; Marcelli, L.; Marini, A.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Murakami, M. Nagano; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perez Cano, S.; Peter, T.; Picozza, P.; Pierog, T.; Piotrowski, L. W.; Piraino, S.; Plebaniak, Z.; Pollini, A.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Reardon, P.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez-Cano, G.; Sagawa, H.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Silva López, H. H.; Sledd, J.; Słomińska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Trillaud, F.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2015-11-01

    Meteor and fireball observations are key to the derivation of both the inventory and physical characterization of small solar system bodies orbiting in the vicinity of the Earth. For several decades, observation of these phenomena has only been possible via ground-based instruments. The proposed JEM-EUSO mission has the potential to become the first operational space-based platform to share this capability. In comparison to the observation of extremely energetic cosmic ray events, which is the primary objective of JEM-EUSO, meteor phenomena are very slow, since their typical speeds are of the order of a few tens of km/sec (whereas cosmic rays travel at light speed). The observing strategy developed to detect meteors may also be applied to the detection of nuclearites, which have higher velocities, a wider range of possible trajectories, but move well below the speed of light and can therefore be considered as slow events for JEM-EUSO. The possible detection of nuclearites greatly enhances the scientific rationale behind the JEM-EUSO mission.

  5. Radar observations of the Volantids meteor shower

    NASA Astrophysics Data System (ADS)

    Younger, J.; Reid, I.; Murphy, D.

    2016-01-01

    A new meteor shower occurring for the first time on 31 December 2015 in the constellation Volans was identified by the CAMS meteor video network in New Zealand. Data from two VHF meteor radars located in Australia and Antarctica have been analyzed using the great circle method to search for Volantids activity. The new shower was found to be active for at least three days over the period 31 December 2015 - 2 January 2016, peaking at an apparent radiant of R.A. = 119.3 ± 3.7, dec. = -74.5 ± 1.9 on January 1st. Measurements of meteoroid velocity were made using the Fresnel transform technique, yielding a geocentric shower velocity of 28.1 ± 1.8 km s-1. The orbital parameters for the parent stream are estimated to be a = 2.11 AU, e = 0.568, i = 47.2°, with a perihelion distance of q = 0.970 AU.

  6. Artificial meteor test towards: On-demand meteor shower

    NASA Astrophysics Data System (ADS)

    Abe, S.; Okajima, L.; Sahara, H.; Watanabe, T.; Nojiri, Y.; Nishizono, T.

    2016-01-01

    An arc-heated wind tunnel is widely used for ground-based experiments to simulate environments of the planetary atmospheric entry under hypersonic and high-temperature conditions. In order to understand details of a meteor ablation such as temperature, composition ratio and fragmentation processes, the artificial meteor test was carried out using a JAXA/ISAS arc-heated wind tunnel. High-heating rate around 30 MW/m2 and High-enthalpy conditions, 10000 K arc-heated flow at velocity around 6 km/s were provided. Newly developed artificial metallic meteoroids and real meteorites such as Chelyabinsk were used for the ablation test. The data obtained by near-ultraviolet and visible spectrograph (200 and 1100nm) and high-speed camera (50 μs) have been examined to develop more efficient artificial meteor materials. We will test artificial meteors from a small satellite in 2018.

  7. 50 CFR 665.209 - Fishing moratorium at Hancock Seamounts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Fishing moratorium at Hancock Seamounts... Hawaii Fisheries § 665.209 Fishing moratorium at Hancock Seamounts. Fishing for, and possession of, Hawaii bottomfish and seamount groundfish MUS in the Hancock Seamounts Ecosystem Management Area...

  8. 50 CFR 665.209 - Fishing moratorium on Hancock Seamount.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Fishing moratorium on Hancock Seamount... Hawaii Fisheries § 665.209 Fishing moratorium on Hancock Seamount. Fishing for Hawaii bottomfish and seamount groundfish MUS on the Hancock Seamount is prohibited through August 31, 2010....

  9. 50 CFR 665.209 - Fishing moratorium at Hancock Seamounts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Fishing moratorium at Hancock Seamounts... Hawaii Fisheries § 665.209 Fishing moratorium at Hancock Seamounts. Fishing for, and possession of, Hawaii bottomfish and seamount groundfish MUS in the Hancock Seamounts Ecosystem Management Area...

  10. 50 CFR 665.209 - Fishing moratorium at Hancock Seamounts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Fishing moratorium at Hancock Seamounts... Hawaii Fisheries § 665.209 Fishing moratorium at Hancock Seamounts. Fishing for, and possession of, Hawaii bottomfish and seamount groundfish MUS in the Hancock Seamounts Ecosystem Management Area...

  11. 50 CFR 665.209 - Fishing moratorium at Hancock Seamounts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Fishing moratorium at Hancock Seamounts... Hawaii Fisheries § 665.209 Fishing moratorium at Hancock Seamounts. Fishing for, and possession of, Hawaii bottomfish and seamount groundfish MUS in the Hancock Seamounts Ecosystem Management Area...

  12. Two slow meteors with spectra

    NASA Astrophysics Data System (ADS)

    Dubs, Martin; Sposetti, Stefano; Spinner, Roger; Booz, Beat

    2017-01-01

    On January 2, 2017 two peculiar meteors (M20170102_001216 and M20170102_015202) were observed by several stations in Switzerland. Both had a long duration, slow velocity, similar brightness and a very similar radiant. As they appeared in a time interval of 100 minutes, a satellite was suspected as a possible origin of these two observations. A closer inspection however showed that this interpretation was incorrect. The two objects were slow meteors. Spectra were taken from both objects, which were nearly identical. Together this points to a common origin of the two meteors.

  13. Pursuing a historical meteor shower

    NASA Astrophysics Data System (ADS)

    Watanabe, Jun-Ichi; Sato, Mikiya; Kasuga, Toshihiro

    2006-11-01

    The strong outburst of the Phoenicids was witnessed by people in a Japanese expedition ship, Soya, in 1956. After that, this meteor shower has never been observed at this activity level. Although its parent comet has not been strictly identified, the possible candidate was the comet D/1819W1 (Blanpain) which appeared only once in 1819. A newly discovered asteroid 2003WY25 becomes a clue to the mystery of this meteor shower. We introduce our result on the investigation of this meteor shower on the basis of the dust trail theory.

  14. Deep-sea fish distribution varies between seamounts: results from a seamount complex off New Zealand.

    PubMed

    Tracey, Dianne M; Clark, Malcolm R; Anderson, Owen F; Kim, Susan W

    2012-01-01

    Fish species data from a complex of seamounts off New Zealand termed the "Graveyard Seamount Complex' were analysed to investigate whether fish species composition varied between seamounts. Five seamount features were included in the study, with summit depths ranging from 748-891 m and elevation from 189-352 m. Measures of fish species dominance, rarity, richness, diversity, and similarity were examined. A number of factors were explored to explain variation in species composition, including latitude, water temperature, summit depth, depth at base, elevation, area, slope, and fishing effort. Depth at base and slope relationships were significant with shallow seamounts having high total species richness, and seamounts with a more gradual slope had high mean species richness. Species similarity was modelled and showed that the explanatory variables were driven primarily by summit depth, as well as by the intensity of fishing effort and elevation. The study showed that fish assemblages on seamounts can vary over very small spatial scales, in the order of several km. However, patterns of species similarity and abundance were inconsistent across the seamounts examined, and these results add to a growing literature suggesting that faunal communities on seamounts may be populated from a broad regional species pool, yet show considerable variation on individual seamounts.

  15. The Southern Argentina Agile Meteor Radar (SAAMER): Platform for comprehensive meteor radar observations and studies

    NASA Astrophysics Data System (ADS)

    Janches, D.; Hormaechea, J.; Pifko, S.; Hocking, W.; Fritts, D.; Brunini, C.; Close, S.; Michell, R.; Samara, M.

    2014-07-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53^oS) in May 2008 (Janches et al., 2013,2014). SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large numbers of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars (Janches et al., 2014). In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions (Pifko et al., 2014). The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, the SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source (Pifko et al., 2014), of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables to survey (Janches et al., 2013). It can effectively observe radiants from the ecliptic south

  16. Meteor Beliefs Project: Seven years and counting

    NASA Astrophysics Data System (ADS)

    McBeath, A.; Drobnock, G. J.; Gheorghe, A. D.

    2010-04-01

    The Meteor Beliefs Project's seventh anniversary is celebrated with an eclectic mixture of meteor beliefs from the 1799 Leonids in Britain, the folkloric link between meteors and wishing in some Anglo-American sources, how a meteoric omen came to feature in Nathaniel Hawthorne's 1850 novel The Scarlet Letter, and a humorous item from the satirical magazine Punch in 1861, all helping to show how meteor beliefs can be transformed by different parts of society.

  17. Coded continuous wave meteor radar

    NASA Astrophysics Data System (ADS)

    Vierinen, Juha; Chau, Jorge L.; Pfeffer, Nico; Clahsen, Matthias; Stober, Gunter

    2016-03-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

  18. How to estimate the affect of an intense meteor

    NASA Astrophysics Data System (ADS)

    Wu, G. J.

    In the present age the potential threat to space projects coming from some intense meteor storms has been noticed Meteoroids have not the big size and great mass of the man-made space debris but they have high velocities up to 11-72 km s -1 and energies In addition a tremendous number of meteoroids might be encountered in a short time Moreover the destroy of the meteoroids is extensive In an impact the shock waves can be generated and propagate along colliding bodies compressing and heating both the target and meteoroid-self A plasma cloud may enclose the target and expands into the surrounding vacuum emitting electromagnetic radiation in a wide spectral range Especially the increasing activity of mankind in space for scientific commercial and military purposes has lead to an increase in safety-related problems about the satellites space stations and astronauts The actual destroy has been recorded many times making the data being lost or solar panels being severely damaged even the satellite lost its control and culminated in an early end of the mission Up to date several new techniques for observing meteors and meteor showers have been developed However the initial definition about a meteor storm based on visual observations with a Zenithal Hourly Rate of above one thousand seems insufficient since it only means a storm or burst of meteors in numbers means an eyewitness could have a chance to see a spectacular meteor show How to define the intense activity of a meteor storm how to estimate and predict the affect of

  19. Detection of uncharted seamounts using satellite altimetry

    SciTech Connect

    Lazarewicz, A.P.; Schwank, D.C.

    1982-04-01

    The topography of the marine geoid (and corresponding sea surface) contains characteristic local features caused by sediments. These features can be successfully detected and located using matched filters to process single tracks of satellite altimeter data. Comparison of detected seamount features with the SNYBAPS and Scripps bathymetric data bases can reveal uncharted seamounts. This technique has been applied to 33 Seasat tracks in a region of the western Pacific bounded by 0 to 15 degrees North and 160 and 165 degrees East. From this analysis, we find three uncharted seamounts in this region. In all three cases, a detailed examination of the bathymetry shows no known bathymetric feature consistent with the detected signature. The method used to estimate the size and location of these uncharted seamounts is discussed.

  20. Kodiak seamount not flat-topped.

    PubMed

    Hamilton, E L; von Huene, R E

    1966-12-09

    Earlier surveys in the Aleutian Trench southeast of Kodiak Island, Alaska, indicated that Kodiak Seamount had a flat top and was a tablemount or guyot. This seamount is of special significance because it has been supposed that its surface was eroded at the same time as those of a line of guyots to the southeast. If so, its present position in the axis of the Aleutian Trench indicates that the line of guyots was formed before the trench. A two-part survey in 1965 showed that Kodiak Seamount is not flat-topped, and should be eliminated from the category of guyots. Reflection profiling records indicate that the seamount was formed before the adjacent sediments were deposited, and that the small trough, or moat, on the south side is a depositional feature probably formed by a scouring effect or by the acceleration of turbidity currents around the base of the mount.

  1. Meteor Beliefs Project: Shakespeare revisited and the Elizabethan stage's `blazing star'

    NASA Astrophysics Data System (ADS)

    Gheorghe, Andrei Dorian; McBeath, Alastair

    2007-06-01

    Some fresh Shakespearean citations of meteors, further to those given previously in the Project, are presented, along with a discussion of the Elizabethan stage's use of the `blazing star', with especial reference to the great comet of 1577.

  2. 75 FR 69015 - Fisheries in the Western Pacific; Hawaii Bottomfish and Seamount Groundfish; Measures To Rebuild...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-10

    ... Pacific; Hawaii Bottomfish and Seamount Groundfish; Measures To Rebuild Overfished Armorhead at Hancock Seamounts AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration... seamount groundfish at the Hancock Seamounts until the overfished U.S. stock of pelagic...

  3. Fisheries Aspects of Seamounts and Taylor Columns

    DTIC Science & Technology

    1986-09-01

    interaction with ocean currents. These recent biological studies have suggested that seamounts may support highly productive ecosystems (Borets, 1975...unique, highly productive ecosystem capable of, if managed properly, maintaining a renewable, commercially feasible resource. Of the seamounts with...the armorhead population. Due to a probable combination of overfishing and poor recruitment, the large fishery of the early 1970’s began a rapid

  4. The Structure and Distribution of Benthic Communities on a Shallow Seamount (Cobb Seamount, Northeast Pacific Ocean)

    PubMed Central

    Curtis, Janelle M. R.; Clarke, M. Elizabeth

    2016-01-01

    Partially owing to their isolation and remote distribution, research on seamounts is still in its infancy, with few comprehensive datasets and empirical evidence supporting or refuting prevailing ecological paradigms. As anthropogenic activity in the high seas increases, so does the need for better understanding of seamount ecosystems and factors that influence the distribution of sensitive benthic communities. This study used quantitative community analyses to detail the structure, diversity, and distribution of benthic mega-epifauna communities on Cobb Seamount, a shallow seamount in the Northeast Pacific Ocean. Underwater vehicles were used to visually survey the benthos and seafloor in ~1600 images (~5 m2 in size) between 34 and 1154 m depth. The analyses of 74 taxa from 11 phyla resulted in the identification of nine communities. Each community was typified by taxa considered to provide biological structure and/or be a primary producer. The majority of the community-defining taxa were either cold-water corals, sponges, or algae. Communities were generally distributed as bands encircling the seamount, and depth was consistently shown to be the strongest environmental proxy of the community-structuring processes. The remaining variability in community structure was partially explained by substrate type, rugosity, and slope. The study used environmental metrics, derived from ship-based multibeam bathymetry, to model the distribution of communities on the seamount. This model was successfully applied to map the distribution of communities on a 220 km2 region of Cobb Seamount. The results of the study support the paradigms that seamounts are diversity 'hotspots', that the majority of seamount communities are at risk to disturbance from bottom fishing, and that seamounts are refugia for biota, while refuting the idea that seamounts have high endemism. PMID:27792782

  5. The Structure and Distribution of Benthic Communities on a Shallow Seamount (Cobb Seamount, Northeast Pacific Ocean).

    PubMed

    Du Preez, Cherisse; Curtis, Janelle M R; Clarke, M Elizabeth

    2016-01-01

    Partially owing to their isolation and remote distribution, research on seamounts is still in its infancy, with few comprehensive datasets and empirical evidence supporting or refuting prevailing ecological paradigms. As anthropogenic activity in the high seas increases, so does the need for better understanding of seamount ecosystems and factors that influence the distribution of sensitive benthic communities. This study used quantitative community analyses to detail the structure, diversity, and distribution of benthic mega-epifauna communities on Cobb Seamount, a shallow seamount in the Northeast Pacific Ocean. Underwater vehicles were used to visually survey the benthos and seafloor in ~1600 images (~5 m2 in size) between 34 and 1154 m depth. The analyses of 74 taxa from 11 phyla resulted in the identification of nine communities. Each community was typified by taxa considered to provide biological structure and/or be a primary producer. The majority of the community-defining taxa were either cold-water corals, sponges, or algae. Communities were generally distributed as bands encircling the seamount, and depth was consistently shown to be the strongest environmental proxy of the community-structuring processes. The remaining variability in community structure was partially explained by substrate type, rugosity, and slope. The study used environmental metrics, derived from ship-based multibeam bathymetry, to model the distribution of communities on the seamount. This model was successfully applied to map the distribution of communities on a 220 km2 region of Cobb Seamount. The results of the study support the paradigms that seamounts are diversity 'hotspots', that the majority of seamount communities are at risk to disturbance from bottom fishing, and that seamounts are refugia for biota, while refuting the idea that seamounts have high endemism.

  6. Database of Properties of Meteors

    NASA Technical Reports Server (NTRS)

    Suggs, Rob; Anthea, Coster

    2006-01-01

    A database of properties of meteors, and software that provides access to the database, are being developed as a contribution to continuing efforts to model the characteristics of meteors with increasing accuracy. Such modeling is necessary for evaluation of the risk of penetration of spacecraft by meteors. For each meteor in the database, the record will include an identification, date and time, radiant properties, ballistic coefficient, radar cross section, size, density, and orbital elements. The property of primary interest in the present case is density, and one of the primary goals in this case is to derive densities of meteors from their atmospheric decelerations. The database and software are expected to be valid anywhere in the solar system. The database will incorporate new data plus results of meteoroid analyses that, heretofore, have not been readily available to the aerospace community. Taken together, the database and software constitute a model that is expected to provide improved estimates of densities and to result in improved risk analyses for interplanetary spacecraft. It is planned to distribute the database and software on a compact disk.

  7. A fast meteor detection algorithm

    NASA Astrophysics Data System (ADS)

    Gural, P.

    2016-01-01

    A low latency meteor detection algorithm for use with fast steering mirrors had been previously developed to track and telescopically follow meteors in real-time (Gural, 2007). It has been rewritten as a generic clustering and tracking software module for meteor detection that meets both the demanding throughput requirements of a Raspberry Pi while also maintaining a high probability of detection. The software interface is generalized to work with various forms of front-end video pre-processing approaches and provides a rich product set of parameterized line detection metrics. Discussion will include the Maximum Temporal Pixel (MTP) compression technique as a fast thresholding option for feeding the detection module, the detection algorithm trade for maximum processing throughput, details on the clustering and tracking methodology, processing products, performance metrics, and a general interface description.

  8. The making of meteor astronomy: part V.

    NASA Astrophysics Data System (ADS)

    Beech, M.

    1993-12-01

    The first true comparisons between the observations and the "rising vapors" hypothesis of meteor origins were made in the early eighteenth century. One of the key figures in the new meteoric dialogue was Edmond Halley.

  9. Meteor Shower Identification and Characterization with Python

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea

    2015-01-01

    The short development time associated with Python and the number of astronomical packages available have led to increased usage within NASA. The Meteoroid Environment Office in particular uses the Python language for a number of applications, including daily meteor shower activity reporting, searches for potential parent bodies of meteor showers, and short dynamical simulations. We present our development of a meteor shower identification code that identifies statistically significant groups of meteors on similar orbits. This code overcomes several challenging characteristics of meteor showers such as drastic differences in uncertainties between meteors and between the orbital elements of a single meteor, and the variation of shower characteristics such as duration with age or planetary perturbations. This code has been proven to successfully and quickly identify unusual meteor activity such as the 2014 kappa Cygnid outburst. We present our algorithm along with these successes and discuss our plans for further code development.

  10. Global Variation of Meteor Trail Plasma Turbulence

    NASA Technical Reports Server (NTRS)

    Dyrud, L. P.; Hinrichs, J.; Urbina, J.

    2011-01-01

    We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere will the resulting trail become plasma turbulent, what are the factors influencing the development of turbulence, and how do they vary on a global scale. Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars, and turbulence influences the evolution of specular radar meteor trails, particularly regarding the inference of mesospheric temperatures from trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and density, and ionospheric plasma density have on the variability of meteor trail evolution and the observation of nonspecular meteor trails, and demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends using non-specular and specular meteor trails.

  11. Leonid meteors, 2001 November 18

    NASA Astrophysics Data System (ADS)

    McGee, H. W.; Mobberley, M. P.

    2002-02-01

    Leonid meteors photographed from Palau, Micronesia, on 2001 November 18. Clockwise from top right: 3 meteors in Corvus, 19.18-19.20 UT; brilliant fireball in Orion, 18.48.30 UT; bright Leonid in Hydra, 19.06 UT. 50mm f/1.8 lens, 1600 ISO Fuji Superia film; M.P. Mobberley. Top left: Composite of three 5-minute exposures between 19.15 and 19.36 UT. 28mm f2.8 lens, 800 ISO Kodak Gold film; H.W. McGee.

  12. Wake in faint television meteors

    NASA Technical Reports Server (NTRS)

    Robertson, M. C.; Hawkes, Robert L.

    1992-01-01

    The two component dustball model was used in numerical lag computation. Detached grain lag is typically less than 2 km, with expected wakes of a few hundred meters. True wake in television meteors is masked by apparent wake due to the combined effects of image persistence and blooming. To partially circumvent this problem, we modified a dual MCP intensified CID video system by addition of a rotating shutter to reduce the effective exposure time to about 2.0 ms. Preliminary observations showed that only 2 of 27 analyzed meteors displayed statistically significant wake.

  13. Flexure modelling at seamounts with dense cores

    NASA Astrophysics Data System (ADS)

    Kim, Seung-Sep; Wessel, Paul

    2010-08-01

    The lithospheric response to seamounts and ocean islands has been successfully described by deformation of an elastic plate induced by a given volcanic load. If the shape and mass of a seamount are known, the lithospheric flexure due to the seamount is determined by the thickness of an elastic plate, Te, which depends on the load density and the age of the plate at the time of seamount construction. We can thus infer important thermomechanical properties of the lithosphere from Te estimates at seamounts and their correlation with other geophysical inferences, such as cooling of the plate. Whereas the bathymetry (i.e. shape) of a seamount is directly observable, the total mass often requires an assumption of the internal seamount structure. The conventional approach considers the seamount to have a uniform density (e.g. density of the crust). This choice, however, tends to bias the total mass acting on an elastic plate. In this study, we will explore a simple approximation to the seamount's internal structure that considers a dense core and a less dense outer edifice. Although the existence of a core is supported by various gravity and seismic studies, the role of such volcanic cores in flexure modelling has not been fully addressed. Here, we present new analytic solutions for plate flexure due to axisymmetric dense core loads, and use them to examine the effects of dense cores in flexure calculations for a variety of synthetic cases. Comparing analytic solutions with and without a core indicates that the flexure model with uniform density underestimates Te by at least 25 per cent. This bias increases when the uniform density is taken to be equal to the crustal density. We also propose a practical application of the dense core model by constructing a uniform density load of same mass as the dense core load. This approximation allows us to compute the flexural deflection and gravity anomaly of a seamount in the wavenumber domain and minimize the limitations

  14. Note on the 1972 Giacobinid meteor shower.

    NASA Technical Reports Server (NTRS)

    Harvey, G. A.

    1973-01-01

    It is shown that the 1972 Giacobinid meteor shower was extremely weak with a peak activity of two to three visual meteors per hour. Only two meteor spectra were obtained from the 17 slitless spectrograph systems operated by the Langley Research Center. The largely unexpected, essentially null results of the 1972 Giacobinid meteor shower observations are indicative of the present limited understanding and predictability of cosmic dust storms.

  15. The new July meteor shower

    NASA Astrophysics Data System (ADS)

    Zoladek, Przemyslaw; Wisniewski, Mariusz

    2012-12-01

    A new meteor stream was found after an activity outburst observed on 2005 July 15. The radiant was located five degrees west of the possible early Perseid radiant, close to the star Zeta Cassiopeiae. Numerous bright meteors and fireballs were observed during this maximum. Analysis of the IMO Video Database and the SonotaCo orbital database revealed an annual stream which is active just before the appearance of the first Perseids, with a clearly visible maximum at solar longitude 113°1. Activity of the stream was estimated as two times higher than activity of the Alpha Capricornids at the same time. The activity period extends from July 12 to 17, during maximum the radiant is visible at coordinates alpha = 5°9, delta = +50°5, and observed meteors are fast, with Vg = 57.4 km/s. The shower was reported to the IAU Meteor Data Center and recognized as a new discovery. According to IAU nomenclature the new stream should be named the Zeta Cassiopeiids (ZCS). %z Arlt R. (1992). WGN, Journal of the IMO, 20:2, 62-69. Drummond J. D. (1981). Icarus, 45, 545-553. Kiraga M. and Olech A. (2001). In Arlt R., Triglav M., and Trayner C., editors, Proceedings of the International Meteor Conference, Pucioasa, Romania, 21-24 September 2000, pages 45-51. IMO. Molau S. (2007). In Bettonvil F. and Kac J., editors, Proceedings of the International Meteor Conference, Roden, The Netherlands, 14-17 September 2006, pages 38-55. IMO. Molau S. and Rendtel J. (2009). WGN, Journal of the IMO, 37:4, 98-121. Olech A., Zoladek P., Wisniewski M., Krasnowski M., Kwinta M., Fajfer T., Fietkiewicz K., Dorosz D., Kowalski L., Olejnik J., Mularczyk K., and Zloczewski K. (2006). In Bastiaens L., Verbert J., Wislez J.-M., and Verbeeck C., editors, Proceedings of the International Meteor Conference, Oostmalle, Belgium, 15-18 September 2005, pages 53-62. IMO. Poleski R. and Szaruga K. (2006). In Bastiaens L., Verbert J., Wislez J.-M., and Verbeeck C., editors, Proceedings of the International Meteor

  16. Croatian Meteor Network: Ongoing work 2015 - 2016

    NASA Astrophysics Data System (ADS)

    Šegon, D.; Vida, D.; Korlević, K.; Andreić, Ž.

    2016-01-01

    Ongoing work of the Croatian Meteor Network (CMN) between the 2015 and 2016 International Meteor Conferences is presented. The current sky coverage is considered, software updates and updates of orbit catalogues are described. Furthermore, the work done on meteor shower searches, international collaborations as well as new fields of research are discussed. Finally, the educational efforts made by the CMN are described.

  17. New trends in meteor radio receivers

    NASA Astrophysics Data System (ADS)

    Rault, Jean-Louis

    2014-01-01

    Recent progresses in low cost—but performing—SDR (software defined radio) technology presents a major breakthrough in the domain of meteor radio observations. Their performances are now good enough for meteor work and should therefore encourage newcomers to join the meteor radio community.

  18. Review of the advances in meteor studies

    NASA Astrophysics Data System (ADS)

    Borovička, J.

    2014-07-01

    I will present a personal conference summary in the field of meteor studies. The most important advances concerning meteors since the last ACM conference (2012 in Japan) will be highlighted. The most interesting event, which occurred in between and was discussed also on this conference, was the Chelyabinsk superbolide. Nevertheless, progress was made also in other meteor studies.

  19. Comparing Eyewitness-Derived Trajectories of Bright Meteors to Ground Truth Data

    NASA Technical Reports Server (NTRS)

    Moser, D. E.

    2016-01-01

    The NASA Meteoroid Environment Office (MEO) is the only US government agency tasked with analyzing meteors of public interest. When queried about a meteor observed over the United States, the MEO must respond with a characterization of the trajectory, orbit, and size within a few hours. Using observations from meteor networks like the NASA All Sky Fireball Network or the Southern Ontario Meteor Network, such a characterization is often easy. If found, casual recordings from the public and stationary web cameras can be used to roughly analyze a meteor if the camera's location can be identified and its imagery calibrated. This technique was used with great success in the analysis of the Chelyabinsk meteorite fall. But if the event is outside meteor network coverage, if an insufficient number of videos are found, or if the imagery cannot be geolocated or calibrated, a timely assessment can be difficult if not impossible. In this situation, visual reports made by eyewitnesses may be the only resource available. This has led to the development of a tool to quickly calculate crude meteor trajectories from eyewitness reports made to the American Meteor Society. The output is illustrated in Figure 1. A description of the tool, example case studies, and a comparison to ground truth data observed by the NASA All Sky Fireball Network will be presented.

  20. Meteor Beliefs Project: Meteors in the Maori astronomical traditions of New Zealand

    NASA Astrophysics Data System (ADS)

    Britton, Tui R.; Hamacher, Duane W.

    2014-02-01

    We review the literature for perceptions of meteors in the Maori culture of Aotearoa or New Zealand. We examine representations of meteors in religion, story, and ceremony. We find that meteors are sometimes personified as gods or children, or are seen as omens of death and destruction. The stories we found highlight the broad perception of meteors found throughout the Maori culture, and note that some early scholars conflated the terms comet and meteor.

  1. Meteor storm forecasting: Leonids 1999-2001

    NASA Astrophysics Data System (ADS)

    Ferrin, I.

    1999-08-01

    We present a method for meteor storm forecasting, that we apply to the Leonids in 1999-2001. The method makes use of a plot where the particle density distribution around the comet is mapped (Fig. 1) and isolines of equal meteor intensity are drawn. The most significant result found is the existence of a ``ridge" or region of high particle density, that corresponds to the great Leonid storms and that we identify with the ``dust trails" that Sykes et al. (1990) and Sykes & Walker (1992) found behind all periodic comets. We present detailed calculations of the trajectories of meteoroids that will reproduce this ridge. We predict the intensity of upcoming Leonid showers by the position of the Earth in relation to the isolines. For 1999 we predict a zenith hourly rate (ZHR) of 3.5 K+/-1 K. For the year 2000 we can only limit the intensity to 5 K

  2. Modeling Meteor Flares for Spacecraft Safety

    NASA Technical Reports Server (NTRS)

    Ehlert, Steven

    2017-01-01

    NASA's Meteoroid Environment Office (MEO) is tasked with assisting spacecraft operators and engineers in quantifying the threat the meteoroid environment poses to their individual missions. A more complete understanding of the meteoroid environment for this application requires extensive observations. One manner by which the MEO observes meteors is with dedicated video camera systems that operate nightly. Connecting the observational data from these video cameras to the relevant physical properties of the ablating meteoroids, however, is subject to sizable observational and theoretical uncertainties. Arguably the most troublesome theoretical uncertainty in ablation is a model for the structure of meteoroids, as observations clearly show behaviors wholly inconsistent with meteoroids being homogeneous spheres. Further complicating the interpretation of the observations in the context of spacecraft risk is the ubiquitous process of fragmentation and the flares it can produce, which greatly muddles any attempts to estimating initial meteoroid masses. In this talk a method of estimating the mass distribution of fragments in flaring meteors using high resolution video observations will be dis- cussed. Such measurements provide an important step in better understanding of the structure and fragmentation process of the parent meteoroids producing these flares, which in turn may lead to better constraints on meteoroid masses and reduced uncertainties in spacecraft risk.

  3. Chasing Meteors With a Microscope.

    ERIC Educational Resources Information Center

    Jones, Richard C.

    1993-01-01

    Describes types of meteors and micrometeorites that enter the Earth's atmosphere. Presents an activity where students collect micrometeorites with a strip of tape in an undisturbed outdoor area. After 24 hours, they examine the tape by sandwiching it between 2 glass slides and view through a microscope at 100X. (PR)

  4. Physical and dynamical studies of meteors

    NASA Technical Reports Server (NTRS)

    Southworth, R. B.; Sekanina, Z.

    1973-01-01

    Interplanetary distributions from a sample of 20,000 radar meteor observations are presented. These distributions are freed from all known selection effects with the exception of a possible bias against fragmenting meteors which has not yet been adequately assessed. These data thus represent the largest and most accurate collection of radar meteor distributions. Both general average distribution and the distribution of meteor streams with their comet and asteroid associations are presented. Sporadic space density and space density of meteor streams are also included.

  5. Meteors Without Borders: a global campaign

    NASA Astrophysics Data System (ADS)

    Heenatigala, T.

    2012-01-01

    "Meteors Without Borders" is a global project, organized by Astronomers Without Borders and launched during the Global Astronomy Month in 2010 for the Lyrid meteor shower. The project focused on encouraging amateur astronomy groups to hold public outreach events for major meteor showers, conduct meteor-related classroom activities, photography, poetry and art work. It also uses social-media platforms to connect groups around the world to share their observations and photography, live during the events. At the International Meteor Conference 2011, the progress of the project was presented along with an extended invitation for collaborations for further improvements of the project.

  6. Recent Advances in Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Meachem, Terry; Cooke, William J.

    2003-01-01

    One of the most common (and obvious) problems with video meteor data involves the saturation of the output signal produced by bright meteors, resulting in the elimination of such meteors from photometric determinations. It is important to realize that a "bright" meteor recorded by intensified meteor camera is not what would be considered "bright" by a visual observer - indeed, many Generation II or III camera systems are saturated by meteors with a visual magnitude of 3, barely even noticeable to the untrained eye. As the relatively small fields of view (approx.30 ) of the camera systems captures at best modest numbers of meteors, even during storm peaks, the loss of meteors brighter than +3 renders the determination of shower population indices from video observations even more difficult. Considerable effort has been devoted by the authors to the study of the meteor camera systems employed during the Marshall Space Flight Center s Leonid ground-based campaigns, and a calibration scheme has been devised which can extend the useful dynamic range of such systems by approximately 4 magnitudes. The calibration setup involves only simple equipment, available to amateur and professional, and it is hoped that use of this technique will make for better meteor photometry, and move video meteor analysis beyond the realm of simple counts.

  7. Determination of the Meteor Limiting Magnitude

    NASA Technical Reports Server (NTRS)

    Kingery, A.; Blaauw, R.; Cooke, W. J.

    2016-01-01

    The limiting meteor magnitude of a meteor camera system will depend on the camera hardware and software, sky conditions, and the location of the meteor radiant. Some of these factors are constants for a given meteor camera system, but many change between meteor shower or sporadic source and on both long and short timescales. Since the limiting meteor magnitude ultimately gets used to calculate the limiting meteor mass for a given data set, it is important to have an understanding of these factors and to monitor how they change throughout the night, as a 0.5 magnitude uncertainty in limiting magnitude translates to a uncertainty in limiting mass by a factor of two.

  8. Pacific seamount volcanism in space and time

    NASA Astrophysics Data System (ADS)

    Hillier, J. K.

    2007-02-01

    Seamounts constitute some of the most direct evidence about intraplate volcanism. As such, when seamounts formed and into which tectonic setting they erupted (i.e. on-ridge or off-ridge) are a useful reflection of how the properties of the lithosphere interact with magma generation in the fluid mantle beneath. Proportionately few seamounts are radiometrically dated however, and these tend to be recently active. In order to more representatively sample and better understand Pacific seamount volcanism this paper estimates the eruption ages (tvolc) of 2706 volcanoes via automated estimates of lithospheric strength. Lithospheric strength (GTRrel) is deduced from the ratio of gravity to topography above the summits of volcanoes, and is shown to correlate with seafloor age at the time of volcanic loading (Δt) at 61 sites where radiometric constraints upon Δt exist. A trend of fits data for these 61, and with seafloor age (tsf) known, can date the 2706 volcanoes; tvolc = tsf - Δt. Widespread recurrences of volcanism proximal to older features (e.g. the Cook-Austral alignment in French Polynesia) suggest that the lithosphere exerts a significant element of control upon the location of volcanism, and that magmatic throughput leaves the lithosphere more susceptible to the passage of future melts. Observations also prompt speculation that: the Tavara seamounts share morphological characteristics and isostatic compensation state with the Musicians, and probably formed similarly; the Easter Island chain may be a modern analogy to the Cross-Lines; a Musicians - South Hawaiian seamounts alignment may be deflecting the Hawaiian hotspot trace.

  9. Jasper Seamount: Seven million years of volcanism

    SciTech Connect

    Pringle, M.S. ); Staudigel, H.; Gee, J. )

    1991-04-01

    Jasper Seamount is a young, mid-sized (690 km{sup 3}) oceanic intraplate volcano located about 500 km west-southwest of San Diego, California. Reliable {sup 40}Ar/{sup 39}Ar age data were obtained for several milligram-sized samples of 4 to 10 Ma plagioclase by using a defocused laser beam to clean the samples before fusion. Gee and Staudigel suggested that Jasper Seamount consists of a transitional to tholeiitic shield volcano formed by flank transitional series lavas, overlain by flank alkalic series lavas and summit alkalic series lavas. Twenty-nine individual {sup 40}Ar/{sup 39}Ar laser fusion analyses on nine samples confirm the stratigraphy: 10.3-10.0 Ma for the flank transitonal series, 8.7-7.5 Ma for the flank alkalic series, and 4.8-4.1 Ma for the summit alkalic series. The alkalinity of the lavas clearly increases with time, and there appear to be 1 to 3 m.y. hiatuses between each series. The age data are consistent with the complex magnetic anomaly of Jasper; however the dominant reversed polarity inferred from the anomaly suggests that most of the seamount formed at ca. 11 Ma, prior to the onset of Chron C5N. The duration of volcanism of Jasper Seamount is slightly longer than the duration of volcanism at Hawaiian volcanoes, suggesting that individual age data from seamounts may constrain the age of a seamount only to within about 7 m.y. unless the stage of volcanism can be unambiguously determined. Extrapolating from the results of our study, similar precision in age determinations should be possible on 50 mg of 1 Ma plagioclase from mid-ocean ridge basalt, opening new possibilities in the geochronology of young, low-potassium volcanic rocks.

  10. Extraterrestrial meteors: a martian meteor and its parent comet.

    PubMed

    Selsis, Franck; Lemmon, Mark T; Vaubaillon, Jérémie; Bell, James F

    2005-06-02

    Regular meteor showers occur when a planet approaches the orbit of a periodic comet--for example, the Leonid shower is evident around 17 November every year as Earth skims past the dusty trail of comet Tempel-Tuttle. Such showers are expected to occur on Mars as well, and on 7 March last year, the panoramic camera of Spirit, the Mars Exploration Rover, revealed a curious streak across the martian sky. Here we show that the timing and orientation of this streak, and the shape of its light curve, are consistent with the existence of a regular meteor shower associated with the comet Wiseman-Skiff, which could be characterized as martian Cepheids.

  11. Petrologic evolution of the Louisville seamount chain

    NASA Astrophysics Data System (ADS)

    Hawkins, James W.; Lonsdale, Peter F.; Batiza, Rodey

    The Louisville Seamount Chain (LSC) extends for 4300 km from Osbourn Seamount, at the junction of the Tonga and Kermadec Trenches, southeasterly towards the Pacific Antarctic Ridge. The chain is formed of 60 or more seamounts and guyots which are aligned along a trend concentric with the Emperor-Hawaii Chain. The Louisville Chain crosses at a low angle several fracture zones which are part of the Eltanin Fracture Zone system, but there is no apparent genetic relation between the two structures. Rocks collected from the Louisville Chain comprise a spectrum of rock types including alkalic basalt, hawaiite, and basanitoid. Some samples have compositions suggesting that they are transitional to tholeiitic basalt, but no true tholeiites have been collected from the seamounts. Osbourn Seamount, at the westernmost end of the chain, is capped with basanitoid; these have been dated as ˜66 Ma. Clinopyroxene phenocrysts in basaltic composition pebbles and detrital grains of clinopyroxene have been recovered from DSDP site 204, north of Osbourn Seamount, at subbottom depths of 112 to 114 meters (Late? Cretaceous age). Some of these pyroxenes have compositions indicating a tholeiitic parental magma, some were derived from alkalic magmas. Osbourn Seamount or an older neighbor were likely sources of the clastic sediments. This is an indication that the early stages of seamount volcanism included tholeiitic magmas, magmatism subsequently evolved through alkalic and basanitic types. Samples dredged from the carapaces of seamounts east of Osbourn are mainly alkalic basalt, or hawaiite, or both. The young, eastern end of the chain near Long. 139°10'W has alkalic basalt lavas. Modeling of trace element and REE data suggest that small amounts (e.g., 4%) melting of garnet Iherzolite could have provided the parental alkalic basalt magmas. Basanitoids represent slightly higher (˜9%) levels of melting. Element ratios of Ti/Zr, Nb/Zr, Y/Zr, Ba/La, La/Ce, La/Sm, Nb/La suggest that the

  12. Meteor observations under the INASAN supervision

    NASA Astrophysics Data System (ADS)

    Kartashova, A. P.; Bagrov, A. V.

    2012-09-01

    Meteor observations have the specific property: we do not know in advance neither area on the celestial sphere, not the time when the event occurs. Besides that, a meteor flash in the atmosphere has duration few seconds or less, and it is hard problem to gather enough photons from it to register a faint or fast meteor. There are a number of tasks in meteor astronomy for solution of which not only a simple registration of meteors in the optical range is required, but a high spatial and time resolution as well. Television method is the most acceptable for such a case and is widely used in the practice of meteor observations. Television meteor observations in Russia are carried out under the Institute of Astronomy of the Russian Academy of Sciences (INASAN) supervision in different regions of Russia: Moscow region, Irkutsk, Ryazan and North Caucasus. The TV system PatrolCa designed for observations in the wide field of view (the ordinary for most of meteor cameras), consists of the following components: the high resolution cameras Watec LCL-902HS, the wide-angle photograph objectives Canon 6/0.8 (F=6 mm, the aperture 1:0.8). The cameras have fields of view of 50°x40° and have a limiting magnitude (for meteors) of +4 m ÷ +5 m. The FAVOR (FAst Variability Optical Registrator) camera is used for observations of faint meteors at the North Caucasus [1]. The basic components of this camera are the following: the high-aperture lense objective with the aperture 150 mm and the focal length 180mm (the aperture 1:1.2), the image intensifier, the objective reversal, CCD receiver "Videoscan" VS-СTT285 2001. The CCD "Sony" ICX285 has format 1380 х 1024 pixels. The camera has a field of view of 18 ° х 20°, and has a limiting magnitude of above +10m (for meteors). The two cameras similar to FAVOR (named SMAC) were designed for double-station observations of faint meteors. The results of observations at these cameras are presented. The observations were held by both methods

  13. A review of the effects of seamounts on biological processes

    NASA Astrophysics Data System (ADS)

    Boehlert, George W.; Genin, Amatzia

    Seamounts interacting with oceanic currents create flow complexities which depend upon current speed, stratification, latitude, and seamount morphology. Seamount effects, which include internal wave generation, eddy formation, local upwelling, and closed circulation patterns called Taylor columns, have important effects upon pelagic and benthic ecosystems over seamounts. The biological effects of these current-topography interactions are poorly understood. Flow acceleration on upper flanks of seamounts may lead to low sedimentation but areas of high standing stocks of benthic fauna, particularly filter feeders. Other effects extend into the water column; nutrient enrichment and enhanced primary productivity occur over some seamounts. Longer observational periods will be necessary to understand the time-varying nature of such enhanced productivity and the extent to which it remains at the seamount or is advected away. At higher trophic levels, unusual patterns of distribution and abundance occur at some seamounts. Maintenance of high standing stocks of seamount-associated micronekton and demersal fishes suggests that seamounts are locations for high rates of energy transfer. The energy driving this biological productivity may either be generated from in situ processes or be advected from elsewhere and concentrated at the seamount; interdisciplinary studies will be necessary to better understand these ecosystems.

  14. Characteristics of Seamounts Near Hawaii as Viewed by GLORIA

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.

    1997-01-01

    Using images and data acquired from the GLORIA sonar system, 390 seamounts within the U.S. Hawaiian Exclusive Economic Zone (HEEZ) off Hawaii have been studied. Their diameters range from 1 to 57 km. with most less than 15 km. Seamount abundance increases exponentially with decreasing size. The areal density of observed seamounts having diameters greater than 1 km is 182/10(exp 6) sq km. The theoretical abundance of seamounts of all sizes normalized to a unit area is (309 +/- 17)/10(exp 6) sq km, about an order of magnitude less than other surveyed areas of the Pacific. This may reflect a lower abundance of Cretaceous seamounts in this region, the covering of small seamounts by sediment, or discrepancies from the use of different data sets to derive the abundance statistics. The seamounts have morphologies ranging from steep-sided, flat-topped structures to cones to more amorphous structures; they are similar to volcanoes found elsewhere on the seafloor. A suite of secondary features associated with the seamounts includes summit craters, summit mounds, coalesced boundaries, landslides, and graben. Several seamount chains are aligned parallel to Cretaceous fracture zones, consistent with an origin close to the ancestral East Pacific Rise. Others are aligned parallel to the Necker Ridge, suggesting that they formed contemporaneously with Necker in the plate interior. This observation, together with high abundances of seamounts where other intraplate igneous processes have occurred, suggests some seamounts formed since leaving the spreading center.

  15. The ALTAIR Meteor Measurements Program

    NASA Technical Reports Server (NTRS)

    Cooke, William J.

    2007-01-01

    Established in late 2006, the Meteor Measurements Program is in the process of using the ALTAIR radar located on Kwajelein Atoll to obtain radar observations of sporadic and shower meteoroids. The goals are to determine meteoroid masses, orbits, ballistic coefficients and densities, which shall be provided to the Meteoroid Environment Office (MEO) at Marshall Space Flight Center. These data and analyses shall then be used by the MEO to 1) Add a realistic density distribution to the new Meteoroid Engineering Model (MEM), which is the specified environment for vehicle design in the NASA Constellation (return to Moon) program. This program is the implementation of President Bush's Vision for Space Exploration (VSE). 2) Investigate the meteoroid velocity distribution at smaller masses. 3) Strive to understand the differences (biases) in meteoroid observations produced by systems like ALTAIR and those of the meteor patrol radars, such as the University of Western Ontario's CMOR system. This paper outlines the program details and its progress.

  16. High temperature condensates among meteors

    NASA Technical Reports Server (NTRS)

    Wilkening, L. L.

    1975-01-01

    It is noted that two meteors which exhibited no lines of iron or sodium in their spectra have been tentatively attributed to aubrites in order to explain their lack of iron. It is shown, however, that no meteorites, including aubrites, have simultaneously low abundances of iron and sodium and that possible parent materials other than aubrites must be considered for the observed meteors. Other possible parent materials considered in this letter include melilite and diopside, two minerals containing both Ca and Mg but neither Fe nor Na. It is suggested that meteoroids rich in Ca and Mg but lacking Fe and Na might form a reservoir for the so-called 'lost' elements (Ca, Mg, Al, Ti, the lanthanides, and other refractory elements) which are depleted in ordinary and enstatite chondrites relative to cosmic abundances.

  17. Artificial meteor ablation studies: Olivine

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Cunningham, G. G.

    1973-01-01

    Artificial meteor ablation was performed on a Mg-rich olivine sample using an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine sample was 98% olivine (including traces of olivine alteration products) and 2% chromite. Forsterite content of the original olivine was Fo-89. After ablation, the forsterite content had increased to Fo-94 in the recrystallized olivine. In addition, lamella-like intergrowths of magnetite were prevalent constituents. Wherever magnetite occurred, there was an increase in Mg and a corresponding decrease in Fe for the recrystallized olivine. The Allende fusion crust consisted of a recrystallized olivine, which was more Mg-rich and Fe-deficient than the original meteorite's olivine, and abundant magnetite grains. Although troilite and pentlandite were the common opaque mineral constituents in this meteorite, magnetite was the principal opaque mineral found in the fusion crust.

  18. The ecology of seamounts: structure, function, and human impacts.

    PubMed

    Clark, Malcolm R; Rowden, Ashley A; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I; Rogers, Alex D; O'Hara, Timothy D; White, Martin; Shank, Timothy M; Hall-Spencer, Jason M

    2010-01-01

    In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.

  19. The Ecology of Seamounts: Structure, Function, and Human Impacts

    NASA Astrophysics Data System (ADS)

    Clark, Malcolm R.; Rowden, Ashley A.; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I.; Rogers, Alex D.; O'Hara, Timothy D.; White, Martin; Shank, Timothy M.; Hall-Spencer, Jason M.

    2010-01-01

    In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.

  20. Kharkiv Meteor Radar System (the XX Age)

    NASA Astrophysics Data System (ADS)

    Kolomiyets, S. V.

    2012-09-01

    Kharkiv meteor radar research are of historic value (Kolomiyets and Sidorov 2007). Kharkiv radar observations of meteors proved internationally as the best in the world, it was noted at the IAU General Assembly in 1958. In the 1970s Kharkiv meteor automated radar system (MARS) was recommended at the international level as a successful prototype for wide distribution. Until now, this radar system is one of the most sensitive instruments of meteor radars in the world for astronomical observations. In 2004 Kharkiv meteor radar system is included in the list of objects which compose the national property of Ukraine. Kharkiv meteor radar system has acquired the status of the important historical astronomical instrument in world history. Meteor Centre for researching meteors in Kharkiv is a analogue of the observatory and performs the same functions of a generator and a battery of special knowledge and skills (the world-famous studio). Kharkiv and the location of the instrument were brand points on the globe, as the place where the world-class meteor radar studies were carried out. They are inscribed in the history of meteor astronomy, in large letters and should be immortalized on a world-wide level.

  1. Meteor Scatter Communication between Thule and Station Nord, Greenland

    DTIC Science & Technology

    1990-09-01

    capacity digital communication channel. In comparison with high yield satellite links, meteor scatter was too complex for widespread utilization then...great companionship during the field campaigns. To Mr. Eric Li , Dr. A. L. Snyder, Jr., Dr. G. S. Sales and Dr. J. A. Weitzen of the University of Lowell...geostationary satellites . Existing polar orbiting satellites intended for data collection are restricted for data of interest to the World Meteorological

  2. Tuna Longline Fishing around West and Central Pacific Seamounts

    PubMed Central

    Morato, Telmo; Hoyle, Simon D.; Allain, Valerie; Nicol, Simon J.

    2010-01-01

    Background Seamounts have been identified as aggregating locations for pelagic biodiversity including tuna; however the topography and prevailing oceanography differ between seamounts and not all are important for tuna. Although a relatively common feature in oceanic ecosystems, little information is available that identifies those that are biologically important. Improved knowledge offers opportunities for unique management of these areas, which may advance the sustainable management of oceanic resources. In this study, we evaluate the existence of an association between seamounts and tuna longline fisheries at the ocean basin scale, identify significant seamounts for tuna in the western and central Pacific Ocean, and quantify the seamount contribution to the tuna longline catch. Methodology/Principal Findings We use data collected for the Western and Central Pacific Ocean for bigeye, yellowfin, and albacore tuna at the ocean basin scale. GLMs were applied to a coupled dataset of longline fisheries catch and effort, and seamount location information. The analyses show that seamounts may be associated with an annual longline combined catch of 35 thousand tonnes, with higher catch apparent for yellowfin, bigeye, and albacore tuna on 17%, 14%, and 14% of seamounts respectively. In contrast 14%, 18%, and 20% of seamounts had significantly lower catches for yellowfin, bigeye and albacore tuna respectively. Studying catch data in relation to seamount positions presents several challenges such as bias in location of seamounts, or lack of spatial resolution of fisheries data. Whilst we recognize these limitations the criteria used for detecting significant seamounts were conservative and the error in identification is likely to be low albeit unknown. Conclusions/Significance Seamounts throughout the study area were found to either enhance or reduce tuna catch. This indicates that management of seamounts is important Pacific-wide, but management approaches must take

  3. Science Priorities for Seamounts: Research Links to Conservation and Management

    PubMed Central

    Clark, Malcolm R.; Schlacher, Thomas A.; Rowden, Ashley A.; Stocks, Karen I.; Consalvey, Mireille

    2012-01-01

    Seamounts shape the topography of all ocean basins and can be hotspots of biological activity in the deep sea. The Census of Marine Life on Seamounts (CenSeam) was a field program that examined seamounts as part of the global Census of Marine Life (CoML) initiative from 2005 to 2010. CenSeam progressed seamount science by collating historical data, collecting new data, undertaking regional and global analyses of seamount biodiversity, mapping species and habitat distributions, challenging established paradigms of seamount ecology, developing new hypotheses, and documenting the impacts of human activities on seamounts. However, because of the large number of seamounts globally, much about the structure, function and connectivity of seamount ecosystems remains unexplored and unknown. Continual, and potentially increasing, threats to seamount resources from fishing and seabed mining are creating a pressing demand for research to inform conservation and management strategies. To meet this need, intensive science effort in the following areas will be needed: 1) Improved physical and biological data; of particular importance is information on seamount location, physical characteristics (e.g. habitat heterogeneity and complexity), more complete and intensive biodiversity inventories, and increased understanding of seamount connectivity and faunal dispersal; 2) New human impact data; these shall encompass better studies on the effects of human activities on seamount ecosystems, as well as monitoring long-term changes in seamount assemblages following impacts (e.g. recovery); 3) Global data repositories; there is a pressing need for more comprehensive fisheries catch and effort data, especially on the high seas, and compilation or maintenance of geological and biodiversity databases that underpin regional and global analyses; 4) Application of support tools in a data-poor environment; conservation and management will have to increasingly rely on predictive modelling

  4. Science priorities for seamounts: research links to conservation and management.

    PubMed

    Clark, Malcolm R; Schlacher, Thomas A; Rowden, Ashley A; Stocks, Karen I; Consalvey, Mireille

    2012-01-01

    Seamounts shape the topography of all ocean basins and can be hotspots of biological activity in the deep sea. The Census of Marine Life on Seamounts (CenSeam) was a field program that examined seamounts as part of the global Census of Marine Life (CoML) initiative from 2005 to 2010. CenSeam progressed seamount science by collating historical data, collecting new data, undertaking regional and global analyses of seamount biodiversity, mapping species and habitat distributions, challenging established paradigms of seamount ecology, developing new hypotheses, and documenting the impacts of human activities on seamounts. However, because of the large number of seamounts globally, much about the structure, function and connectivity of seamount ecosystems remains unexplored and unknown. Continual, and potentially increasing, threats to seamount resources from fishing and seabed mining are creating a pressing demand for research to inform conservation and management strategies. To meet this need, intensive science effort in the following areas will be needed: 1) Improved physical and biological data; of particular importance is information on seamount location, physical characteristics (e.g. habitat heterogeneity and complexity), more complete and intensive biodiversity inventories, and increased understanding of seamount connectivity and faunal dispersal; 2) New human impact data; these shall encompass better studies on the effects of human activities on seamount ecosystems, as well as monitoring long-term changes in seamount assemblages following impacts (e.g. recovery); 3) Global data repositories; there is a pressing need for more comprehensive fisheries catch and effort data, especially on the high seas, and compilation or maintenance of geological and biodiversity databases that underpin regional and global analyses; 4) Application of support tools in a data-poor environment; conservation and management will have to increasingly rely on predictive modelling

  5. Big data era in meteor science

    NASA Astrophysics Data System (ADS)

    Vinković, D.; Gritsevich, M.; Srećković, V.; Pečnik, B.; Szabó, G.; Debattista, V.; Škoda, P.; Mahabal, A.; Peltoniemi, J.; Mönkölä, S.; Mickaelian, A.; Turunen, E.; Kákona, J.; Koskinen, J.; Grokhovsky, V.

    2016-01-01

    Over the last couple of decades technological advancements in observational techniques in meteor science have yielded drastic improvements in the quality, quantity and diversity of meteor data, while even more ambitious instruments are about to become operational. This empowers meteor science to boost its experimental and theoretical horizons and seek more advanced science goals. We review some of the developments that push meteor science into the big data era that requires more complex methodological approaches through interdisciplinary collaborations with other branches of physics and computer science. We argue that meteor science should become an integral part of large surveys in astronomy, aeronomy and space physics, and tackle the complexity of micro-physics of meteor plasma and its interaction with the atmosphere.

  6. Meteor Beliefs Project: Meteoric Imagery in SF, Part V: This Island Earth

    NASA Astrophysics Data System (ADS)

    McBeath, Alastair; Gheorghe, Andrei Dorian

    2007-04-01

    The classic 1950s science fiction film This Island Earth is discussed for its meteoric elements, along with a more recent movie which pokes fun at it, by way of celebrating the Meteor Beliefs Project's fourth anniversary.

  7. 75 FR 52921 - Fisheries in the Western Pacific; Hawaii Bottomfish and Seamount Groundfish; Management Measures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... Pacific; Hawaii Bottomfish and Seamount Groundfish; Management Measures for Hancock Seamounts to Rebuild... continue a moratorium on fishing for bottomfish and seamount groundfish at the Hancock Seamounts until the... also reclassify the management area around the Hancock Seamounts as an ecosystem management area....

  8. The Upsilon Pegasid Meteor Shower

    NASA Astrophysics Data System (ADS)

    Povenmire, H.

    1995-09-01

    On the morning of August 8, 1975, meteors were observed from a previously unrecognized radiant in Pegasus. The rates were approximately seven per hour [1]. The radiant was alpha = 350 degrees, delta = +19 degrees (2000.0). These meteors are characterized as swift, yellow-white and without significant ionization trains [1]. The average magnitude of several hundred meteors from this shower is approximately +3.50, slightly fainter than the Perseids which occur at the same time. A broad maximum seems to occur about August 8. The three active fireball networks (Prairie, MORP and European) were contacted in a search for previously recorded fireballs with negative results. Ceplecha [2] of the European Network computed the orbital elements using the FIRBAL program. On August 19, 1982 at 02:09:57 UT, a magnitude -14.76 f1reball occurred over the White Carpathian Mountains of Austria and Czechoslovakia. It was photographed by five cameras of the European Network. Reduction of this Upsilon Pegasid fireball (EN 190882A) showed it to be a type IIIb fireball [2] - that is, an extremely low density, cometary, snow-like material with a specific gravity of approximately 0.27 g/cm^3. This material ablates at high altitude and cannot produce sonic phenomena or meteorites. It is similar to the material in the Draconid meteor shower. The orbital elements derived from EN 190882A are given in Table I. Table I: Orbital elements for the Upsilon Pegasid stream from EN 190882A. omega = 305.9009 degrees Omega = 145.3431 degrees i = 85.0817 degrees q = 0.2022 e = 1.0 velocity = 51.8608 km/s Using these refined elements, Kronk [3] computed the radiant drift. The radiant drifts from the SSW to NNE at a relatively steep angle and at an average rate of 20 arc-min per day. An intensive literature search [3] revealed four double station Upsilon Pegasids which had previously been listed as sporadics. Institutions providing these data were Yale [4], Stalinabad [5], Tadjikistan [6] and Harvard [7

  9. Dynasonde Measurements of Ionospheric Meteor Effects

    NASA Astrophysics Data System (ADS)

    Berkey, F. T.; Sikdar, P.; Fish, C. S.; Jones, O.; Tsai, L.; Yen, C.

    2002-12-01

    The ionization created when meteoric particles impinge on the upper atmosphere has been studied extensively, both with optical methods and by radar techniques. Traditionally, meteor radars have been configured as dedicated, fixed-frequency systems that operate in the HF/VHF bands and are employed to measure winds and other parameters in the mesosphere-lower thermosphere region. It has long been recognized that ionosondes are capable of detecting meteor ionization although the sparse sounding format of most synoptic instruments does not facilitate a rigorous analysis of meteor ionization effects. Furthermore, most ionosonde-based studies have focused on meteor shower intervals when the meteor ionization is especially prominent (e.g. Chandra et. al., 2001). However, the capabilities of digital ionosondes such as the NOAA dynasonde allow the detailed study of various parameters of the meteor-induced ionization such as amplitude, polarization and spatial location, in addition to the time-of-flight, as a function of time and frequency. In this report, we will examine meteor ionization recorded by dynasondes located at Bear Lake (Utah) and Halley (Antarctica) demonstrating that these ionogram data can be used to distinguish between underdense and overdense meteor ionization. Other characteristics of the meteor-induced ionization, such as spatial location and Doppler velocity will also be presented. The dynasonde operated at the USU Bear Lake Observatory (42° N, 111° W) detects a large flux of meteor echoes and will be the primary source of data for this study. Chandra, H., et. al., Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes, Annales. Geophys., 19, 59-69, 2001.

  10. The Seamount Catalog in EarthRef.org

    NASA Astrophysics Data System (ADS)

    Keizer, P.; Koppers, A.; Staudigel, H.; Helly, J.

    2001-12-01

    Seamounts are prominent features on the ocean floor that provide us with important insights to geology, geochemistry, geophysics and paleoclimate. To make accessible a diverse set of seamount data we developed the Seamount Catalog on the EarthRef.org web site that is accessible via http://earthref.org/databases/SC/. The goal of our effort is to provide simple access to the widest possible variety in digital data files as related to seamount research in a geospatial context. Each seamount is described in terms of its location, basic morphological features, and the types of data available in the catalog. The Seamount Catalog includes a series of basic bathymetry maps, processed grid files and original multibeam data. At least one screen-optimized JPEG file is available for online viewing and the remaining (higher resolution) files are directly downloadable from the EarthRef.org web site. The grid files are based on multibeam bathymetry data merged with the predicted bathymetry database of Smith and Sandwell (1996; 1997). The Seamount Catalog data objects are extensively described in terms of metadata allowing for searches by location (lat/lon), region name, seamount name, sample name or reference. We hope to further develop the Seamount Catalog by adding geophysical and other seamount data, expanding its metadata catalog, working towards a metadata interchange format (*.mif) and establishing interoperability with other data bases. The geospatial character of the Seamount Catalog would allow for interoperability between existing geochemistry, paleomagnetic and biological (biota) databases. Data files available for downloading will be stored using the Storage Resource Broker technology (SRB) while the generated metadata will be stored in the Seamount Catalog itself. Such developments represent the first steps towards the creation of a digital seamount research environment that includes electronic access to data and ultimately also the tools for working with the data.

  11. Morphology and distribution of seamounts surrounding Easter Island

    USGS Publications Warehouse

    Rappaport, Y.; Naar, D.F.; Barton, C.C.; Liu, Z.-J.; Hey, R.N.

    1997-01-01

    We investigate the morphology and distribution of a seamount population on a section of seafloor influenced by both superfast seafloor spreading and hotspot volcanism. The population under investigation is part of a broad chain of seamounts extending eastward from the East Pacific Rise, near Easter Island. In order to define the morphological variability of the seamounts, basal shape, cross-sectional area, volume, flatness, and flank slope are plotted against height for 383 seamounts with heights greater than 200 m, based on bathymetry data collected by GLORI-B and SeaBeam 2000, during three cruises onboard the R/V Melville in the spring of 1993. Nearly complete swath mapping coverage of the seamounts is available for the analysis of size and shape distribution. We quantitatively describe the seamount population of this active region, in which seamounts cover ???27% of the seafloor, and account for ???4.2% of the total crustal volume. Over 50% of the total volume (61,000 km3) of seamounts used in this study is made up by the 14 largest seamounts, and the remaining volume is made up by the 369 smaller seamounts (>200 m in height). Our analysis indicates there are at least two seamount populations in the Easter Island-Salas y Gomez Island (25??-29??S, 113??-104??W) study area. One population of seamounts is composed of short seamounts (1200 m), shield-like, pointy cones (flatness ???1200 m) originate exclusively from a hotspot source, but only a portion of the smaller volcanoes (

  12. Fluid flow through seamounts and implications for global mass fluxes

    NASA Astrophysics Data System (ADS)

    Harris, Robert N.; Fisher, Andrew T.; Chapman, David S.

    2004-08-01

    Seamounts contribute to globally significant hydrothermal fluxes, but the dynamics and impacts of fluid flow through these features are poorly understood. Numerical models of coupled heat and fluid flow illustrate how seamounts induce local convection in the oceanic crust. We consider idealized axisymmetric seamounts and calculate mass and heat fluxes by using a coupled heat- and fluid-flow model. By using P. Wessel's global database of ˜15,000 seamounts identified through satellite gravimetry, we estimate that the mass flux associated with seamounts is ˜1014 kg/yr, a number comparable to estimated regional mass fluxes through mid-ocean ridges and flanks. In addition, the seamount-generated advective heat flux may be locally significant well beyond the 65 Ma average age at which advective lithospheric heat loss on ridge flanks ends. These flows may be important for facilitating geochemical exchange between the crust and ocean and may affect subseafloor microbial ecosystems.

  13. The origin of the Canary Island Seamount Province - New ages of old seamounts

    PubMed Central

    van den Bogaard, Paul

    2013-01-01

    The Canary Island Seamount Province forms a scattered hotspot track on the Atlantic ocean floor ~1300 km long and ~350 km wide, perpendicular to lithospheric fractures, and parallel to the NW African continental margin. New 40Ar/39Ar datings show that seamount ages vary from 133 Ma to 0.2 Ma in the central archipelago, and from 142 Ma to 91 Ma in the southwest. Combining 40Ar/39Ar ages with plate tectonic reconstructions, I find that the temporal and spatial distribution of seamounts is irreconcilable with a deep fixed mantle plume origin, or derivation from passive mantle upwelling beneath a mid-ocean ridge. I conclude that shallow mantle upwelling beneath the Atlantic Ocean basin off the NW African continental lithosphere flanks produced recurrent melting anomalies and seamounts from the Late Jurassic to Recent, nominating the Canary Island Seamount Province as oldest hotspot track in the Atlantic Ocean, and most long-lived preserved on earth. PMID:23838703

  14. The origin of the Canary Island Seamount Province - new ages of old seamounts.

    PubMed

    van den Bogaard, Paul

    2013-01-01

    The Canary Island Seamount Province forms a scattered hotspot track on the Atlantic ocean floor ~1300 km long and ~350 km wide, perpendicular to lithospheric fractures, and parallel to the NW African continental margin. New (40)Ar/(39)Ar datings show that seamount ages vary from 133 Ma to 0.2 Ma in the central archipelago, and from 142 Ma to 91 Ma in the southwest. Combining (40)Ar/(39)Ar ages with plate tectonic reconstructions, I find that the temporal and spatial distribution of seamounts is irreconcilable with a deep fixed mantle plume origin, or derivation from passive mantle upwelling beneath a mid-ocean ridge. I conclude that shallow mantle upwelling beneath the Atlantic Ocean basin off the NW African continental lithosphere flanks produced recurrent melting anomalies and seamounts from the Late Jurassic to Recent, nominating the Canary Island Seamount Province as oldest hotspot track in the Atlantic Ocean, and most long-lived preserved on earth.

  15. Meteor spectra in the EDMOND database

    NASA Astrophysics Data System (ADS)

    Koukal, J.; Gorková, S.; Srba, J.; Ferus, M.; Civiš, S.; di Pietro, C. A.

    2015-01-01

    We present a selection of five interesting meteor spectra obtained in the years 2014 and 2015 via CCTV video systems with a holographic grating, working in CEMENT and BRAMON meteor observation networks. Based on the EDMOND multi stations video meteor trajectory data an orbital classification of these meteors was performed. Selected meteors are members of the LYR, SPE, DSA and LVI meteor streams, one meteor is classified as sporadic background (SPO). In calibrated spectra the main chemical components were identified. Meteors are chemically classified based on relative intensities of the main spectral lines (or multiplets): Mg I (2), Na I (1), and Fe I (15). Bolide EN091214 is linked with the 23rd meteorite with known orbit (informally known as "Žďár"), two fragments of the parent body were found in the Czech Republic so far (August, 2015). For this particular event a time resolved spectral observation and comparison with laboratory spectra of LL3.2 chondritic meteorite are presented.

  16. Meteor Terminology poster translated into different languages

    NASA Astrophysics Data System (ADS)

    Perlerin, Vincent; Hankey, Mike

    2014-02-01

    The American Meteor Society (AMS) has created an educational poster that defines the major terms of the meteor terminology. This poster is an educational tool made available for free on the AMS website. We offer this poster to be translated and shared among the IMO members.

  17. Croatian Meteor Network: ongoing work 2014 - 2015

    NASA Astrophysics Data System (ADS)

    Šegon, D.; Andreić, Ž.; Korlević, K.; Vida, D.

    2015-01-01

    Ongoing work mainly between 2014-2015 International Meteor Conferences (IMC) has been presented. Current sky coverage, software updates, orbit catalogues updates, shower search updates, international collaboration as well as new fields of research and educational efforts made by the Croatian Meteor Network are described.

  18. Meteor radio detection. (Italian Title: Radiometeore, oggi)

    NASA Astrophysics Data System (ADS)

    Aglialoro, A.; Devetti, M.

    2013-08-01

    Meteor detection using the radio technique called "Meteor-Scatter" and some results obtained since 2005 by our team. This kind of activity has become difficult after the switch-off of analog TV; a hope may be a French VHF trasmitter: the Graves radar.

  19. Models of sporadic meteor body distributions

    NASA Technical Reports Server (NTRS)

    Andreev, V. V.; Belkovich, O. I.

    1987-01-01

    The distribution of orbital elements and flux density over the celestial sphere are the most common forms of representation of the meteor body distribution in the vicinity of the Earth's orbit. The determination of flux density distribution of sporadic meteor bodies was worked out. The method and its results are discussed.

  20. The Makings of Meteor Astronomy: Part XIII

    NASA Astrophysics Data System (ADS)

    Beech, M.

    1996-10-01

    In 1848, Sir John Lubbock advanced the hypothesis that meteors shine by reflected sunlight. He developed a set of equations describing the geometry of meteor encounters, and for a decade or so, his idea was at least marginally supported by other observers.

  1. Seamounts, Direct Blast and Volume Reverberation Upgrades

    DTIC Science & Technology

    1988-11-30

    Highway. Suits 1204. Arlington, VA 22202-4302. "n to the Office of Management and Budget. Peperworik Reduction Project (0704-0188). Washington. DC 2050M. 1...Subtitle. 5. Funding Numbers. Seamounts, Direct Blast And Volume Reverberation Upgrades proram Eemen No 3 7 85N Project No R02017 6. Author(s). L...Section Pae 1 INTRODUCTION ................................. 1-1 2 ASERT: DATA PREPARATION FOR ASTRAL ........... 2-1 2.1 Overview and Purpose of

  2. NOAA Research Vessel Explores Atlantic Ocean Seamounts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2014-10-01

    Mike Ford, a biological oceanographer with the National Oceanic and Atmospheric Administration (NOAA), sat rapt in front of a bank of high-definition monitors. They provided live video and data feeds from a tethered pair of instrument-laden remotely operated vehicles (ROVs) that were descending 4692 meters on their deepest dive ever. Their target: an unnamed and unexplored New England seamount discovered in the North Atlantic last year.

  3. Geophysical Age Dating of Seamounts using Dense Core Flexure Model

    NASA Astrophysics Data System (ADS)

    Hwang, Gyuha; Kim, Seung-Sep

    2016-04-01

    Lithospheric flexure of oceanic plate is thermo-mechanical response of an elastic plate to the given volcanic construct (e.g., seamounts and ocean islands). If the shape and mass of such volcanic loads are known, the flexural response is governed by the thickness of elastic plate, Te. As the age of oceanic plate increases, the elastic thickness of oceanic lithosphere becomes thicker. Thus, we can relate Te with the age of plate at the time of loading. To estimate the amount of the driving force due to seamounts on elastic plate, one needs to approximate their density structure. The most common choice is uniform density model, which utilizes constant density value for a seamount. This approach simplifies computational processes for gravity prediction and error estimates. However, the uniform density model tends to overestimate the total mass of the seamount and hence produces more positive gravitational contributions from the load. Minimization of gravity misfits using uniform density, therefore, favors thinner Te in order to increase negative contributions from the lithospheric flexure, which can compensate for the excessive positives from the seamount. An alternative approach is dense core model, which approximate the heterogeneity nature of seamount density as three bodies of infill sediment, edifice, and dense core. In this study, we apply the dense core model to the Louisville Seamount Chain for constraining flexural deformation. We compare Te estimates with the loading time of the examined seamounts to redefine empirical geophysical age dating of seamounts.

  4. Visual data of minor meteor showers limits of the method

    NASA Technical Reports Server (NTRS)

    Rendtel, Jurgen; Koschack, R.

    1992-01-01

    Visual meteor observations are carried out on a regular basis by many experienced observers worldwide, thus supplying information about activity of meteor showers. The limits of the method are determined by the accuracy of the detection of the meteor trail. This study shows that visual meteor observations provide reliable data for an observable hourly rate of greater than or equal to 3.

  5. The First Confirmed Videorecordings of Lunar Meteor Impacts

    NASA Technical Reports Server (NTRS)

    Dunham, D. W.; Cudnik, B.; Palmer, D. M.; Sada, P. V.; Melosh, J.; Beech, M.; Pellerin, L.; Asher, D.; Frankenberger R.; Venable R.

    2000-01-01

    North American observers recorded at least six meteors striking the Moon's surface during the Leonid meteor shower on 1999 Nov. 18. Each meteor produced a flash that was recorded from at least two separate locations, marking the first confirmed lunar meteor impacts.

  6. Radio Meteors Observations Techniques at RI NAO

    NASA Astrophysics Data System (ADS)

    Vovk, Vasyl; Kaliuzhnyi, Mykola

    2016-07-01

    The Solar system is inhabited with large number of celestial bodies. Some of them are well studied, such as planets and vast majority of big asteroids and comets. There is one group of objects which has received little attention. That is meteoroids with related to them meteors. Nowadays enough low-technology high-efficiency radio-technical solutions are appeared which allow to observe meteors daily. At RI NAO three methodologies for meteor observation are developed: single-station method using FM-receiver, correlation method using FM-receiver and Internet resources, and single-station method using low-cost SDR-receiver.

  7. The 2014 May Camelopardalid Meteor Shower

    NASA Technical Reports Server (NTRS)

    Cooke, Bill; Moser, Danielle

    2014-01-01

    On May 24, 2014 Earth will encounter multiple streams of debris laid down by Comet 209P LINEAR. This will likely produce a new meteor shower, never before seen. Rates predicted to be from 100 to 1000 meteors per hour between 2 and 4 AM EDT, so we are dealing with a meteor outburst, potentially a storm. Peak rate of 200 per hour best current estimate. Difficult to calibrate models due to lack of past observations. Models indicate mm size particles in stream, so potential risk to Earth orbiting spacecraft.

  8. Calibrating Video Cameras For Meteor Works

    NASA Astrophysics Data System (ADS)

    Khaleghy-Rad, Mona; Campbell-Brown, M.

    2006-09-01

    The calculation of the intensity of light produced by a meteor ablating in the atmosphere is crucial to determination of meteoroid masses, and to uncovering the meteoroid's physical structure through ablation modeling. A necessary step in the determination is to use cameras which have been end-to-end calibrated to determine their precise spectral response. We report here a new procedure for calibrating low-light video cameras used for meteor observing, which will be used in conjunction with average meteor spectra to determine absolute light intensities.

  9. Detecting small seamounts in AltiKa repeat cycle data

    NASA Astrophysics Data System (ADS)

    Marks, K. M.; Smith, W. H. F.

    2016-12-01

    We present a technique of stacking repeat cycles of satellite altimeter sea surface height profiles that lowers the noise and improves the resolution of small seamounts. Our approach differs from other studies because it uses the median (not the mean) of the stacks, which suppresses outliers. Seamounts as small as 720 m tall are easily detected in stacked 40 Hz AltiKa data profiles, and a 500 m tall seamount is perceptible. Noise variance decreases with an increase in the number of cycles stacked, and RMS noise dips below 2 cm when 11 or more cycles are stacked. Coherence analyses between geoid height and bathymetry show that full wavelengths down to about 10 km can be resolved. Comparisons of study areas with and without seamounts find that signal from small seamounts lies in the 10-28 km waveband. A simple Gaussian band-pass filter based on the seamount waveband passes signals that can be used in seamount detection studies. Such studies may find seamounts <2 km tall that are predicted to be abundant on the ocean floor.

  10. Physical and dynamical studies of meteors. Meteor-fragmentation and stream-distribution studies

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.; Southworth, R. B.

    1975-01-01

    Population parameters of 275 streams including 20 additional streams in the synoptic-year sample were found by a computer technique. Some 16 percent of the sample is in these streams. Four meteor streams that have close orbital resemblance to Adonis cannot be positively identified as meteors ejected by Adonis within the last 12000 years. Ceplecha's discrete levels of meteor height are not evident in radar meteors. The spread of meteoroid fragments along their common trajectory was computed for most of the observed radar meteors. There is an unexpected relationship between spread and velocity that perhaps conceals relationships between fragmentation and orbits; a theoretical treatment will be necessary to resolve these relationships. Revised unbiased statistics of synoptic-year orbits are presented, together with parallel statistics for the 1961 to 1965 radar meteor orbits.

  11. Analysis of the technical biases of meteor video cameras used in the CILBO system

    NASA Astrophysics Data System (ADS)

    Albin, Thomas; Koschny, Detlef; Molau, Sirko; Srama, Ralf; Poppe, Björn

    2017-02-01

    In this paper, we analyse the technical biases of two intensified video cameras, ICC7 and ICC9, of the double-station meteor camera system CILBO (Canary Island Long-Baseline Observatory). This is done to thoroughly understand the effects of the camera systems on the scientific data analysis. We expect a number of errors or biases that come from the system: instrumental errors, algorithmic errors and statistical errors. We analyse different observational properties, in particular the detected meteor magnitudes, apparent velocities, estimated goodness-of-fit of the astrometric measurements with respect to a great circle and the distortion of the camera. We find that, due to a loss of sensitivity towards the edges, the cameras detect only about 55 % of the meteors it could detect if it had a constant sensitivity. This detection efficiency is a function of the apparent meteor velocity. We analyse the optical distortion of the system and the goodness-of-fit of individual meteor position measurements relative to a fitted great circle. The astrometric error is dominated by uncertainties in the measurement of the meteor attributed to blooming, distortion of the meteor image and the development of a wake for some meteors. The distortion of the video images can be neglected. We compare the results of the two identical camera systems and find systematic differences. For example, the peak magnitude distribution for ICC9 is shifted by about 0.2-0.4 mag towards fainter magnitudes. This can be explained by the different pointing directions of the cameras. Since both cameras monitor the same volume in the atmosphere roughly between the two islands of Tenerife and La Palma, one camera (ICC7) points towards the west, the other one (ICC9) to the east. In particular, in the morning hours the apex source is close to the field-of-view of ICC9. Thus, these meteors appear slower, increasing the dwell time on a pixel. This is favourable for the detection of a meteor of a given

  12. Video meteor detection filtering using soft computing methods

    NASA Astrophysics Data System (ADS)

    Silađi, E.; Vida, D.; Nyarko, K.

    2015-01-01

    In this paper we present the current progress and results from the filtering of Croatian Meteor Network video meteor detections using soft computing methods such as neural networks and support vector machines (SVMs). The goal is to minimize the number of false-positives while preserving the real meteor detections. This is achieved by pre-processing the data to extract meteor movement parameters and then recognizing patterns distinct to meteors. The input data format is fully compliant with the CAMS meteor data standard, and as such the proposed method could be utilized by other meteor networks of the similar kind.

  13. Effects of meteoric debris on stratospheric aerosols and gases

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Toon, O. B.; Whitten, R. C.; Hamill, P.

    1981-01-01

    Characterizations of meteoric dust height and size distributions are obtained using Hunten's calculations of meteor ablation and recondensation rates. The contribution of meteor residues to aerosol composition, the role of meteoric dust as condensation nuclei, and the effects of meteor debris on aerosol size distributions are quantified, and particle surface areas are estimated. The potential importance of heterogeneous chemistry for stratospheric trace gases is discussed. The interaction between H2SO4 vapor and meteor metal vapors is investigated. It is concluded that meteoric particles may dominate the natural stratospheric aerosols at small (less than .01 micron radius) and large (greater than 1 micron radius) sizes under normal conditions.

  14. Geochemistry of hydrothermal plume in the Suiyo Seamount Caldera.

    NASA Astrophysics Data System (ADS)

    Shitashima, K.; Maeda, Y.

    2002-12-01

    Chemical compounds of the hot basalt origin are discharged into the deep ocean via hydrothermal plume by the deep-sea hydrothermal activity. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the hydrothermal plume are important to comprehend the oceanic geochemical cycles. Recently, it has been clarified that the variation of hydrothermal activity is greatly controlled in the tidal current. Not only geochemical observation but also physical observation, such as water current measurement, are necessary for the understanding of the deep-sea hydrothermal systems including the behavior of hydrothermal plume. In order to observe the diffusion process of hydrothermal plumes, sampling and chemical mapping of the hydrothermal plume and measurement of water current were carried out at the Suiyo Seamount Caldera during research cruises under the ?Archaean Park? project funded by MEXT. The three-dimensional acoustic current meters were moored at the height of 13m and 125m above the bottom in the Suiyo Seamount Caldera. At the 13m height, average water current speed and current direction were 10.46 cm/second and 228.1 degrees, respectively, and maximum water current speed was over 40.46 cm/second. On the other hand, average water current speed and current direction at the 125m height were 3.87 cm/second and 57.8 degrees, respectively. The strong water current of the southwest direction in 24 hours periods existed near bottom of the caldera. In addition, downward current and water temperature depreciation were observed, when there was the strong current in 24 hours periods. These results suggest that the low-temperature ocean water around the Suiyo Seamount flows toward the bottom of caldera periodically. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles and the in-situ pH sensor were installed on the ROV or manned submersible. The hydrothermal plume

  15. Emplacement and Growth of Serpentinite Seamounts on the Mariana Forearc

    NASA Astrophysics Data System (ADS)

    Oakley, A. J.; Taylor, B.; Moore, G. F.; Fryer, P.; Morgan, J. K.; Goodliffe, A. M.

    2004-12-01

    Seamounts comprised primarily of serpentinite muds are found on the outer forearc of the Izu-Bonin-Mariana subduction system. They represent some of the first material outputs of the recycling process that takes place in subduction zones. Therefore, understanding their evolution is necessary to correctly quantify the flux of material through the subduction system. Serpentinite seamounts have been described as mud diapirs, mud volcanoes, uplifted blocks of mantle material, and a composite of the latter two. Multi-channel seismic (MCS) data collected in 2002 from the outer Mariana forearc imaged, for the first time, the large-scale internal structure of these seamounts. These data, combined with new bathymetry, have provided insight into how the seamounts grow and deform with time and have allowed us to evaluate proposed models for their formation. The serpentinite seamounts rest on faulted and sedimented Mariana forearc basement. Flank flows of serpentinite muds downlap existing forearc substrate, leaving the underlying stratigraphy largely undisturbed. Reflections located 3.5-5 km beneath forearc basement may represent Moho, suggesting that the seamounts are built on anomalously thin forearc crust. A strong reflection at the summit of Big Blue, the largest serpentinite seamount in the Mariana Forearc, represents a collapse structure that has been partially in-filled by younger muds, supporting the idea that serpentinite seamount growth is episodic. Basal thrusts that incorporate forearc sediments at the toe of Turquoise Seamount provide evidence for seamount settling and lateral growth. We are conducting numerical simulations of seamount growth and evolution using the discrete element method (DEM), previously used to examine gravity spreading phenomena in magmatic volcanoes. Simulations employing distinctly low basal and internal friction coefficients provide a good match to the overall morphology of the serpentinite seamounts, and offer insight into their internal

  16. Quantitative Study of Seismogenic Potential Along Manila Trench: Effects of Scaborough Seamount Chain Subduction

    NASA Astrophysics Data System (ADS)

    Yu, H.; Liu, Y.; Li, D.; Ning, J.; Matsuzawa, T.; Shibazaki, B.; Hsu, Y. J.

    2014-12-01

    Modern seismicity record along the Manila Trench shows only infrequent Mw7 earthquakes, the lack of great earthquakes may indicate the subduction fault is either aseismically slipping or is accumulating strain energy toward rapid release in a megathrust earthquake. We conduct numerical simulations of the plate coupling, earthquake nucleation and dynamic rupture propagation processes along the Manila subduction fault (15-19.5ºN), taking into consideration the effects of plate geometry (including subducted seamounts), fault strength, rate-state frictional properties and pore pressure variations. Specifically, we use the bathymetry to depict the outline of Manila trench along its strike, 2681 background seismicity (1970/02/13 to 2013/09/06) from Chinese Earthquake Network Center and 540 focal mechanism solutions (1976/01/01 to 2013/01/27) from Global CMT project to constrain the geometry of the subducting Sunda/Eurasian slab. The compilation of seismicity and focal mechanism indicates the plate dipping angle gradually changes from 28º (south of the Scaborough Seamount Chain) to 12º (north of it). This geometric anomaly may due to the subducted part of the seamount chain. Preliminary modeling results using gabbro gouge friction data show that the Scaborough Seamount Chain could be a barrier to earthquake rupture propagation. Only earthquakes larger than Mw7 can overcome the barrier to rupture the entire Manila trench. Smaller earthquakes would cease rupturing when it encounters the seamount chain. Moreover, we propose that Manila trench subduction zone has the potential of rupturing in a Mw8 megathrust earthquake, if the simulation period is long enough for an Mw8 earthquake cycle and dynamic rupture overcomes the subducted Scaborough Seamount Chain. Our model parameters will be further constrained by laboratory rock mechanics experiments conducted on IODP Expedition 349, South China Sea (SCS), drilling samples (work in progress at China Earthquake Administration

  17. Microbial Ecology of Subseafloor Communities at Deep-sea Hydrothermal Seamounts of the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Bolton, S.; Butterfield, D. A.; Baross, J. A.; Sogin, M. L.

    2006-12-01

    Circulation of hydrothermal fluids and seawater occurs within the upper 500 m of porous oceanic crust and provides a rich environment for microbial growth in the subseafloor. Enrichment cultures, geochemical indicators, and sequence analyses of PCR amplicons of ribosomal RNA genes demonstrate that these crustal fluids host a microbial community composed of organisms indigenous to the subseafloor and organisms from other deep-sea habitats, such as seawater. However, the subseafloor microbial communities remain undersampled and our knowledge of what microbes are present and how they are distributed in this dynamic environment over time and space is fragmentary. This work focuses on determining the microbial diversity and genomic content of the subseafloor microbial community at geographically and geochemically distinct deep- sea hydrothermal seamounts. The approach uses a combination of methods, including DNA-based, culturing, and geochemical methods applied to diffuse fluids from two locations: Axial Seamount on the Juan de Fuca Ridge in the northeast Pacific Ocean (45.92° N, 130° W) and seamounts along the Mariana Arc (14-22° N, 143-146° E) in the western Pacific. Both locations host recently eruptive seamounts located above 2000 m with diffusely venting fluids that contain high concentrations of carbon dioxide. However, their geological and chemical setting differs greatly; Axial is a mid-ocean ridge seamount with fluids dominated by high concentrations of hydrogen sulfide, and the Mariana seamounts are at a convergent plate boundary and host a variety of fluids, including those with very low pH and high concentrations of particulate sulfur. Initial studies reveal bacterial communities at both sites consist mainly of epsilon-proteobacteria, a physiologically and phylogenetically diverse group known to have a widespread distribution and dominance in many deep-sea vent habitats. However, while subseafloor archaeal communities at Axial are composed of autotrophic

  18. The KUT meteor radar: An educational low cost meteor observation system by radio forward scattering

    NASA Astrophysics Data System (ADS)

    Madkour, W.; Yamamoto, M.

    2016-01-01

    The Kochi University of Technology (KUT) meteor radar is an educational low cost observation system built at Kochi, Japan by successive graduate students since 2004. The system takes advantage of the continuous VHF- band beacon signal emitted from Fukui National College of Technology (FNCT) for scientific usage all over Japan by receiving the forward scattered signals. The system uses the classical forward scattering setup similar to the setup described by the international meteor organization (IMO), gradually developed from the most basic single antenna setup to the multi-site meteor path determination setup. The primary objective is to automate the observation of the meteor parameters continuously to provide amounts of data sufficient for statistical analysis. The developed software system automates the observation of the astronomical meteor parameters such as meteor direction, velocity and trajectory. Also, automated counting of meteor echoes and their durations are used to observe mesospheric ozone concentration by analyzing the duration distribution of different meteor showers. The meteor parameters observed and the methodology used for each are briefly summarized.

  19. Oceanic sharks clean at coastal seamount.

    PubMed

    Oliver, Simon P; Hussey, Nigel E; Turner, John R; Beckett, Alison J

    2011-03-14

    Interactions between pelagic thresher sharks (Alopias pelagicus) and cleaner wrasse were investigated at a seamount in the Philippines. Cleaning associations between sharks and teleosts are poorly understood, but the observable interactions seen at this site may explain why these mainly oceanic sharks regularly venture into shallow coastal waters where they are vulnerable to disturbance from human activity. From 1,230 hours of observations recorded by remote video camera between July 2005 and December 2009, 97 cleaner-thresher shark events were analyzed, 19 of which were interrupted. Observations of pelagic thresher sharks interacting with cleaners at the seamount were recorded at all times of day but their frequency declined gradually from morning until evening. Cleaners showed preferences for foraging on specific areas of a thresher shark's body. For all events combined, cleaners were observed to conduct 2,757 inspections, of which 33.9% took place on the shark's pelvis, 23.3% on the pectoral fins, 22.3% on the caudal fin, 8.6% on the body, 8.3% on the head, 2.1% on the dorsal fin, and 1.5% on the gills respectively. Cleaners did not preferentially inspect thresher sharks by time of day or by shark sex, but there was a direct correlation between the amount of time a thresher shark spent at a cleaning station and the number of inspections it received. Thresher shark clients modified their behavior by "circular-stance-swimming," presumably to facilitate cleaner inspections. The cleaner-thresher shark association reflected some of the known behavioral trends in the cleaner-reef teleost system since cleaners appeared to forage selectively on shark clients. Evidence is mounting that in addition to acting as social refuges and foraging grounds for large visiting marine predators, seamounts may also support pelagic ecology by functioning as cleaning stations for oceanic sharks and rays.

  20. Large Meteor Tracked over Northeast Alabama

    NASA Video Gallery

    On the evening of May 18, NASA all-sky meteor cameras located at NASA’s Marshall Space Flight Center and at the Walker County Science Center near Chickamauga, Ga. tracked the entry of a large meteo...

  1. Monte Carlo modeling and meteor showers

    NASA Technical Reports Server (NTRS)

    Kulikova, N. V.

    1987-01-01

    Prediction of short lived increases in the cosmic dust influx, the concentration in lower thermosphere of atoms and ions of meteor origin and the determination of the frequency of micrometeor impacts on spacecraft are all of scientific and practical interest and all require adequate models of meteor showers at an early stage of their existence. A Monte Carlo model of meteor matter ejection from a parent body at any point of space was worked out by other researchers. This scheme is described. According to the scheme, the formation of ten well known meteor streams was simulated and the possibility of genetic affinity of each of them with the most probable parent comet was analyzed. Some of the results are presented.

  2. Man-Sized Meteor Over Macon

    NASA Video Gallery

    Astronomers at NASA's Marshall Space Flight Center have recorded the brightest meteor ever seen by their network. On May 20, 2011, six-foot diameter fragment of an unknown comet entered the atmosph...

  3. Comparison with Russian analyses of meteor impact

    SciTech Connect

    Canavan, G.H.

    1997-06-01

    The inversion model for meteor impacts is used to discuss Russian analyses and compare principal results. For common input parameters, the models produce consistent estimates of impactor parameters. Directions for future research are discussed and prioritized.

  4. SAGE III/Meteor - 3M

    NASA Technical Reports Server (NTRS)

    1999-01-01

    From left to right: Richard Rawls, Chip Holloway, and Art Hayhurst standing next to the Stratospheric Aerosol Gastropheric Experiment (SAGE)/Meteor - 3M flight instrument. Photographed in building 1250, 40 foot clean room.

  5. SAGE III/Meteor - 3M

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Back view of the SAGE III Bench Checkout Unit, Portable Image Generator (PIG) on tripod, and the Stratospheric Aerosol Gastropheric Experiment (SAGE)/Meteor - 3M flight instrument. Photographed in building 1250, 40 foot clean room.

  6. SAGE III/Meteor - 3M

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Full view of the SAGE III Bench Checkout Unit, Collimated Source Bench (CSB), Portable Image Generator (PIG) on tripod, and Stratospheric Aerosol Gastropheric Experiment (SAGE)/Meteor - 3M flight instrument. Photographed in building 1250, 40 foot clean room.

  7. Meteor showers associated with 2003EH1

    NASA Astrophysics Data System (ADS)

    Babadzhanov, P. B.; Williams, I. P.; Kokhirova, G. I.

    2008-06-01

    Using the Everhart RADAU19 numerical integration method, the orbital evolution of the near-Earth asteroid 2003EH1 is investigated. This asteroid belongs to the Amor group and is moving on a comet-like orbit. The integrations are performed over one cycle of variation of the perihelion argument ω. Over such a cycle, the orbit intersect that of the Earth at eight different values of ω. The orbital parameters are different at each of these intersections and so a meteoroid stream surrounding such an orbit can produce eight different meteor showers, one at each crossing. The geocentric radiants and velocities of the eight theoretical meteor showers associated with these crossing points are determined. Using published data, observed meteor showers are identified with each of the theoretically predicted showers. The character of the orbit and the existence of observed meteor showers associated with 2003EH1 confirm the supposition that this object is an extinct comet.

  8. Analysis of ALTAIR 1998 Meteor Radar Data

    NASA Technical Reports Server (NTRS)

    Zinn, J.; Close, S.; Colestock, P. L.; MacDonell, A.; Loveland, R.

    2011-01-01

    We describe a new analysis of a set of 32 UHF meteor radar traces recorded with the 422 MHz ALTAIR radar facility in November 1998. Emphasis is on the velocity measurements, and on inferences that can be drawn from them regarding the meteor masses and mass densities. We find that the velocity vs altitude data can be fitted as quadratic functions of the path integrals of the atmospheric densities vs distance, and deceleration rates derived from those fits all show the expected behavior of increasing with decreasing altitude. We also describe a computer model of the coupled processes of collisional heating, radiative cooling, evaporative cooling and ablation, and deceleration - for meteors composed of defined mixtures of mineral constituents. For each of the cases in the data set we ran the model starting with the measured initial velocity and trajectory inclination, and with various trial values of the quantity mPs 2 (the initial mass times the mass density squared), and then compared the computed deceleration vs altitude curves vs the measured ones. In this way we arrived at the best-fit values of the mPs 2 for each of the measured meteor traces. Then further, assuming various trial values of the density Ps, we compared the computed mass vs altitude curves with similar curves for the same set of meteors determined previously from the measured radar cross sections and an electrostatic scattering model. In this way we arrived at estimates of the best-fit mass densities Ps for each of the cases. Keywords meteor ALTAIR radar analysis 1 Introduction This paper describes a new analysis of a set of 422 MHz meteor scatter radar data recorded with the ALTAIR High-Power-Large-Aperture radar facility at Kwajalein Atoll on 18 November 1998. The exceptional accuracy/precision of the ALTAIR tracking data allow us to determine quite accurate meteor trajectories, velocities and deceleration rates. The measurements and velocity/deceleration data analysis are described in Sections

  9. 75 FR 51237 - Fisheries in the Western Pacific; Hawaii Bottomfish and Seamount Groundfish; Management Measures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

    ... Pacific; Hawaii Bottomfish and Seamount Groundfish; Management Measures for Hancock Seamounts to Rebuild...), Amendment 2 would continue a moratorium on fishing at Hancock Seamounts for armorhead (Pseudopentaceros wheeleri) and other bottomfish and seamount groundfish until the armorhead stock is rebuilt, establish...

  10. Meteor showers of the southern hemisphere

    NASA Astrophysics Data System (ADS)

    Molau, Sirko; Kerr, Steve

    2014-04-01

    We present the results of an exhaustive meteor shower search in the southern hemisphere. The underlying data set is a subset of the IMO Video Meteor Database comprising 50,000 single station meteors obtained by three Australian cameras between 2001 and 2012. The detection technique was similar to previous single station analysis. In the data set we find 4 major and 6 minor northern hemisphere meteor showers, and 12 segments of the Antihelion source (including the Northern and Southern Taurids and six streams from the MDC working list). We present details for 14 southern hemisphere showers plus the Centaurid and Puppid-Velid complex, with the η Aquariids and the Southern δ Aquariids being the strongest southern showers. Two of the showers (θ^2 Sagittariids and τ Cetids) were previously unknown and have received preliminary designations by the MDC. Overall we find that the fraction of southern meteor showers south of -30deg declination (roughly 25%) is clearly smaller than the fraction of northern meteor showers north of +30deg declination (more than 50%) obtained in our previous analysis.

  11. Meteoric Ions in Planetary Ionospheres

    NASA Technical Reports Server (NTRS)

    Pesnell, W. D.; Grebowsky, Joseph M.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Solar system debris, in the form of meteoroids, impacts every planet. The flux, relative composition and speed of the debris at each planet depends on the planet's size and location in the solar system. Ablation in the atmosphere evaporates the meteoric material and leaves behind metal atoms. During the ablation process metallic ions are formed by impact ionization. For small inner solar system planets, including Earth, this source of ionization is typically small compared to either photoionization or charge exchange with ambient molecular ions. For Earth, the atmosphere above the main deposition region absorbs the spectral lines capable of ionizing the major metallic atoms (Fe and Mg) so that charge exchange with ambient ions is the dominant source. Within the carbon dioxide atmosphere of Mars (and possibly Venus), photoionization is important in determining the ion density. For a heavy planet like Jupiter, far from the sun, impact ionization of ablated neutral atoms by impacts with molecules becomes a prominent source of ionization due to the gravitational acceleration to high incident speeds. We will describe the processes and location and extent of metal ion layers for Mars, Earth and Jupiter, concentrating on flagging the uncertainties in the models at the present time. This is an important problem, because low altitude ionosphere layers for the planets, particularly at night, probably consist predominantly of metallic ions. Comparisons with Earth will be used to illustrate the differing processes in the three planetary atmospheres.

  12. Jasper Seamount: seven million years of volcanism

    USGS Publications Warehouse

    Pringle, M.S.; Staudigel, H.; Gee, J.

    1991-01-01

    Jasper Seamount is a young, mid-sized (690 km3) oceanic intraplate volcano located about 500 km west-southwest of San Diego, California. Reliable 40Ar/39Ar age data were obtained for several milligram-sized samples of 4 to 10 Ma plagioclase by using a defocused laser beam to clean the samples before fusion. Gee and Staudigel suggested that Jasper Seamount consists of a transitional to tholeiitic shield volcano formed by flank transitional series lavas, overlain by flank alkalic series lavas and summit alkalic series lavas. Twenty-nine individual 40Ar/39Ar laser fusion analyses on nine samples confirm the stratigraphy: 10.3-10.0 Ma for the flank transitional series, 8.7-7.5 Ma for the flank alkalic series, and 4.8-4.1 Ma for the summit alkalic series. The alkalinity of the lavas clearly increases with time, and there appear to be 1 to 3 m.y. hiatuses between each series. -from Authors

  13. Seamounts are hotspots of pelagic biodiversity in the open ocean

    PubMed Central

    Morato, Telmo; Hoyle, Simon D.; Allain, Valerie; Nicol, Simon J.

    2010-01-01

    The identification of biodiversity hotspots and their management for conservation have been hypothesized as effective ways to protect many species. There has been a significant effort to identify and map these areas at a global scale, but the coarse resolution of most datasets masks the small-scale patterns associated with coastal habitats or seamounts. Here we used tuna longline observer data to investigate the role of seamounts in aggregating large pelagic biodiversity and to identify which pelagic species are associated with seamounts. Our analysis indicates that seamounts are hotspots of pelagic biodiversity. Higher species richness was detected in association with seamounts than with coastal or oceanic areas. Seamounts were found to have higher species diversity within 30–40 km of the summit, whereas for sets close to coastal habitat the diversity was lower and fairly constant with distance. Higher probability of capture and higher number of fish caught were detected for some shark, billfish, tuna, and other by-catch species. The study supports hypotheses that seamounts may be areas of special interest for management for marine pelagic predators. PMID:20448197

  14. Seamounts are hotspots of pelagic biodiversity in the open ocean.

    PubMed

    Morato, Telmo; Hoyle, Simon D; Allain, Valerie; Nicol, Simon J

    2010-05-25

    The identification of biodiversity hotspots and their management for conservation have been hypothesized as effective ways to protect many species. There has been a significant effort to identify and map these areas at a global scale, but the coarse resolution of most datasets masks the small-scale patterns associated with coastal habitats or seamounts. Here we used tuna longline observer data to investigate the role of seamounts in aggregating large pelagic biodiversity and to identify which pelagic species are associated with seamounts. Our analysis indicates that seamounts are hotspots of pelagic biodiversity. Higher species richness was detected in association with seamounts than with coastal or oceanic areas. Seamounts were found to have higher species diversity within 30-40 km of the summit, whereas for sets close to coastal habitat the diversity was lower and fairly constant with distance. Higher probability of capture and higher number of fish caught were detected for some shark, billfish, tuna, and other by-catch species. The study supports hypotheses that seamounts may be areas of special interest for management for marine pelagic predators.

  15. Seismic detections of the 15 February 2013 Chelyabinsk meteor from the dense ChinArray

    NASA Astrophysics Data System (ADS)

    Li, Lu; Wang, Baoshan; Peng, Zhigang; Wang, Weitao

    2016-08-01

    ChinArray is a dense portable broadband seismic network to cover the entire continental China, and the Phase I is deployed along the north-south seismic belt in southwest China. In this study, we analyze seismic data recorded on the ChinArray following the February 15, 2013 Chelyabinsk (Russia) meteor. This was the largest known object entering the Earth's atmosphere since the 1908 Tunguska meteor. The seismic energy radiated from this event was recorded by seismic stations worldwide including the dense ChinArray that are more than 4000 km away. The weak signal from the meteor event was contaminated by a magnitude 5.8 Tonga earthquake occurred ~20 min earlier. To test the feasibility of detecting the weak seismic signals from the meteor event, we compute vespagram and perform F-K analysis to the surface-wave data. We identify a seismic phase with back azimuth (BAZ) of 329.7° and slowness of 34.73 s/deg, corresponding to the surface wave from the Russian meteor event (BAZ ~325.97°). The surface magnitude ( M S) of the meteor event is 3.94 ± 0.18. We also perform similar analysis on the data from the broadband array F-net in Japan, and find the BAZ of the surface waves to be 316.61°. With the different BAZs of ChinArray and F-net, we locate the Russian meteor event at 58.80°N, 58.72°E. The relatively large mislocation (~438 km as compared with 55.15°N, 61.41°E by others) may be a result of the bending propagation path of surface waves, which deviates from the great circle path. Our results suggest that the dense ChinArray and its subarrays could be used to detect weak signals at teleseismic distances.

  16. Mesospheric temperature estimation from meteor decay times during Geminids meteor shower

    NASA Astrophysics Data System (ADS)

    Kozlovsky, Alexander; Lukianova, Renata; Shalimov, Sergey; Lester, Mark

    2016-02-01

    Meteor radar observations at the Sodankylä Geophysical Observatory (67° 22'N, 26° 38'E, Finland) indicate that the mesospheric temperature derived from meteor decay times is systematically underestimated by 20-50 K during the Geminids meteor shower which has peak on 13 December. A very good coincidence of the minimum of routinely calculated temperature and maximum of meteor flux (the number of meteors detected per day) was observed regularly on that day in December 2008-2014. These observations are for a specific height-lifetime distribution of the Geminids meteor trails and indicate a larger percentage of overdense trails compared to that for sporadic meteors. A consequence of this is that the routine estimates of mesospheric temperature during the Geminids are in fact underestimates. The observations do, however, indicate unusual properties (e.g., mass, speed, or chemical composition) of the Geminids meteoroids. Similar properties were found also for Quadrantids in January 2009-2015, which like the Geminids has as a parent body an asteroid, but not for other meteor showers.

  17. An Ecosystem Evaluation Framework for Global Seamount Conservation and Management

    PubMed Central

    Taranto, Gerald H.; Kvile, Kristina Ø.; Pitcher, Tony J.; Morato, Telmo

    2012-01-01

    In the last twenty years, several global targets for protection of marine biodiversity have been adopted but have failed. The Convention on Biological Diversity (CBD) aims at preserving 10% of all the marine biomes by 2020. For achieving this goal, ecologically or biologically significant areas (EBSA) have to be identified in all biogeographic regions. However, the methodologies for identifying the best suitable areas are still to be agreed. Here, we propose a framework for applying the CBD criteria to locate potential ecologically or biologically significant seamount areas based on the best information currently available. The framework combines the likelihood of a seamount constituting an EBSA and its level of human impact and can be used at global, regional and local scales. This methodology allows the classification of individual seamounts into four major portfolio conservation categories which can help optimize management efforts toward the protection of the most suitable areas. The framework was tested against 1000 dummy seamounts and satisfactorily assigned seamounts to proper EBSA and threats categories. Additionally, the framework was applied to eight case study seamounts that were included in three out of four portfolio categories: areas highly likely to be identified as EBSA with high degree of threat; areas highly likely to be EBSA with low degree of threat; and areas with a low likelihood of being EBSA with high degree of threat. This framework will allow managers to identify seamount EBSAs and to prioritize their policies in terms of protecting undisturbed areas, disturbed areas for recovery of habitats and species, or both based on their management objectives. It also identifies seamount EBSAs and threats considering different ecological groups in both pelagic and benthic communities. Therefore, this framework may represent an important tool to mitigate seamount biodiversity loss and to achieve the 2020 CBD goals. PMID:22905190

  18. An ecosystem evaluation framework for global seamount conservation and management.

    PubMed

    Taranto, Gerald H; Kvile, Kristina Ø; Pitcher, Tony J; Morato, Telmo

    2012-01-01

    In the last twenty years, several global targets for protection of marine biodiversity have been adopted but have failed. The Convention on Biological Diversity (CBD) aims at preserving 10% of all the marine biomes by 2020. For achieving this goal, ecologically or biologically significant areas (EBSA) have to be identified in all biogeographic regions. However, the methodologies for identifying the best suitable areas are still to be agreed. Here, we propose a framework for applying the CBD criteria to locate potential ecologically or biologically significant seamount areas based on the best information currently available. The framework combines the likelihood of a seamount constituting an EBSA and its level of human impact and can be used at global, regional and local scales. This methodology allows the classification of individual seamounts into four major portfolio conservation categories which can help optimize management efforts toward the protection of the most suitable areas. The framework was tested against 1000 dummy seamounts and satisfactorily assigned seamounts to proper EBSA and threats categories. Additionally, the framework was applied to eight case study seamounts that were included in three out of four portfolio categories: areas highly likely to be identified as EBSA with high degree of threat; areas highly likely to be EBSA with low degree of threat; and areas with a low likelihood of being EBSA with high degree of threat. This framework will allow managers to identify seamount EBSAs and to prioritize their policies in terms of protecting undisturbed areas, disturbed areas for recovery of habitats and species, or both based on their management objectives. It also identifies seamount EBSAs and threats considering different ecological groups in both pelagic and benthic communities. Therefore, this framework may represent an important tool to mitigate seamount biodiversity loss and to achieve the 2020 CBD goals.

  19. State-of-the-art meteor observing

    NASA Astrophysics Data System (ADS)

    Campbell-Brown, M.

    2014-07-01

    Meteors are an excellent way to sample the local population of small asteroidal and cometary material. Various methods are used to calculate the trajectory, energy, mass and orbit of meteoroids which collide with the atmosphere. Optical methods, including photographic and video observations, can provide information on how meteoroids ablate in the atmosphere, and from this their chemical and physical properties can be inferred. New observing systems have higher resolution than ever before, allowing details as small as a few meters to be distinguished in some cases (e.g. Weryk et al. 2013), and some optical systems are equipped with spectral detectors which allow the atomic composition of the meteoroids to be obtained. Computer automation of both the observing and data reduction process has become much more practical recently. Meteor patrol radars are capable of observing thousands of meteor orbits every day, allowing the details of the distribution of meteoroids at 1 au to be found (e.g. Brown et al. 2010). Radars can operate in daylight and through clouds, providing observations when optical methods fail. High power, large aperture radars allow the ionization curves of very small meteors to be used in the same way as optical light curves, and can also produce precise orbits for meteoroids (Kero et al. 2012). Other methods used to observe meteors, including infrasound, can estimate their position in the atmosphere and their energy, and are particularly useful for very bright fireballs (Ens et al., 2012). Recent advances in meteor observing techniques will be reviewed, including the systematic tracking of meteors with computer guided mirrors and a telescope, and multistation patrol radar observations.

  20. BRAMS: The Belgian RAdio Meteor Stations

    NASA Technical Reports Server (NTRS)

    Lamy, H.; Ranvier, S.; De Keyser, J.; Calders, S.; Gamby, E.; Verbeeck, C.

    2011-01-01

    In the last months, the Belgian Institute for Space Aeronomy has been developing a Belgian network for observing radio meteors using forward scattering technique. This network is called BRAMS for Belgian RAdio Meteor Stations. Two beacons emitting a circularly polarized pure sine wave toward the zenith act as the transmitters at frequencies of 49.97 and 49.99 MHz. The first one located in Dourbes (Southern Belgium) emits a constant power of 150 Watts while the one located in Ieper (Western Belgium) emits a constant power of 50 Watts. The receiving network consists of about 20 stations hosted mainly by radio amateurs. Two stations have crossed-Yagi antennas measuring horizontal and vertical polarizations of the waves reflected off meteor trails. This will enable a detailed analysis of the meteor power profiles from which physical parameters of the meteoroids can be obtained. An interferometer consisting of 5 Yagi-antennas will be installed at the site of Humain in order to determine the angular detection of one reflection point, allowing us to determine meteoroid trajectories. We describe this new meteor observing facility and present the goals we expect to achieve with the network.

  1. CAMS confirmation of previously reported meteor showers

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.; Nénon, Q.; Gural, P. S.; Albers, J.; Haberman, B.; Johnson, B.; Holman, D.; Morales, R.; Grigsby, B. J.; Samuels, D.; Johannink, C.

    2016-03-01

    Leading up to the 2015 IAU General Assembly, the International Astronomical Union's Working List of Meteor Showers included 486 unconfirmed showers, showers that are not certain to exist. If confirmed, each shower would provide a record of past comet or asteroid activity. Now, we report that 41 of these are detected in the Cameras for Allsky Meteor Surveillance (CAMS) video-based meteor shower survey. They manifest as meteoroids arriving at Earth from a similar direction and orbit, after removing the daily radiant drift due to Earth's motion around the Sun. These showers do exist and, therefore, can be moved to the IAU List of Established Meteor Showers. This adds to 31 previously confirmed showers from CAMS data. For each shower, finding charts are presented based on 230,000 meteors observed up to March of 2015, calculated by re-projecting the drift-corrected Sun-centered ecliptic coordinates into more familiar equatorial coordinates. Showers that are not detected, but should have, and duplicate showers that project to the same Sun-centered ecliptic coordinates, are recommended for removal from the Working List.

  2. Optical Meteor Systems Used by the NASA Meteoroid Environment Office

    NASA Technical Reports Server (NTRS)

    Kingery, A. M.; Blaauw, R. C.; Cooke, W. J.; Moser, D. E.

    2015-01-01

    The NASA Meteoroid Environment Office (MEO) uses two main meteor camera networks to characterize the meteoroid environment: an all sky system and a wide field system to study cm and mm size meteors respectively. The NASA All Sky Fireball Network consists of fifteen meteor video cameras in the United States, with plans to expand to eighteen cameras by the end of 2015. The camera design and All-Sky Guided and Real-time Detection (ASGARD) meteor detection software [1, 2] were adopted from the University of Western Ontario's Southern Ontario Meteor Network (SOMN). After seven years of operation, the network has detected over 12,000 multi-station meteors, including meteors from at least 53 different meteor showers. The network is used for speed distribution determination, characterization of meteor showers and sporadic sources, and for informing the public on bright meteor events. The NASA Wide Field Meteor Network was established in December of 2012 with two cameras and expanded to eight cameras in December of 2014. The two camera configuration saw 5470 meteors over two years of operation with two cameras, and has detected 3423 meteors in the first five months of operation (Dec 12, 2014 - May 12, 2015) with eight cameras. We expect to see over 10,000 meteors per year with the expanded system. The cameras have a 20 degree field of view and an approximate limiting meteor magnitude of +5. The network's primary goal is determining the nightly shower and sporadic meteor fluxes. Both camera networks function almost fully autonomously with little human interaction required for upkeep and analysis. The cameras send their data to a central server for storage and automatic analysis. Every morning the servers automatically generates an e-mail and web page containing an analysis of the previous night's events. The current status of the networks will be described, alongside with preliminary results. In addition, future projects, CCD photometry and broadband meteor color camera

  3. Search for seamounts in the southern Cook and Austral region

    SciTech Connect

    Lambeck, K.; Coleman, R.

    1982-04-01

    The existence of uncharted seamounts in the Cook-Austral region of the South Pacific has been investigated using GEOS 3 and SEASAT radar altimeter observations. Three previously uncharted submarine seamounts, provisionally named GEOS A to GEOS C, have been located between Mauke and Rimatara and a fourth, GEOS D, has been located east of Rurutu. This confirms that the Aitutaki-Mauke islands of the Southern Cooks are a continuation of the Austral chain. A second group of uncharted seamounts has been provisionally located some 200 km south of Rimatara and Maria and this is suggestive of a second seamount chain, south of the first, that includes Raratonga and Mangaia. Fabert Bank, to the south of Mangaia, appears to be mislocated by about 2/sup 0/ in longitude.

  4. Lagrangian observations of surface circulation at the Emperor Seamount chain

    NASA Technical Reports Server (NTRS)

    Vastano, A. C.; Hagan, D. E.; Mcnally, G. J.

    1985-01-01

    In a Kuroshio tracking experiment initiated in February 1977, two satellite-reporting buoys, drogued to 100-m depth, were released southeast of Kuyshu Island, Japan. These drifters crossed the Shatskiy Rise in the Kuroshio extension during May and October and then traversed the Emperor Seamount Chain. Although they reached the chain 117 days apart, their movements near the seamounts display remarkably similar patterns, demonstrating upstream meanders in the surface flow; cyclonic eddy activity immediately west of the chain; passage through the same gap associated with the Jingu and Nintoku seamounts; and a wavelike pattern present over the Hess Rise east of the chain. One drifter exhibited cyclonic eddy motion east of the chain in the lee of the Kinmei Seamount.

  5. Subduction of the Daiichi Kashima Seamount in the Japan Trench

    USGS Publications Warehouse

    Lallemand, S.; Culotta, R.; Von Huene, R.

    1989-01-01

    In 1984-1985, the Kaiko consortium collected Seabeam, single-channel seismic and submersible sampling data in the vicinity of the Daiichi-Kashima seamount and the southern Japan trench. We performed a prestack migration of a Shell multichannel seismic profile, that crosses this area, and examined it in the light of this unusually diverse Kaiko dataset. Unlike the frontal structure of the northern Japan trench, where mass-wasting appears to be the dominant tectonic process, the margin in front of the Daiichi-Kashima shows indentation, imbrication, uplift and erosion. Emplacement of the front one-third of the seamount beneath the margin front occurs without accretion. We conclude that the Daiichi-Kashima seamount exemplifies an intermediate stage between the initial collision and subduction of a seamount at a continental margin. ?? 1989.

  6. Thermal Constraints on Upper Basement Permeability Near a Venting Seamount

    NASA Astrophysics Data System (ADS)

    Hutnak, M.; Fisher, A. T.; Zuehlsdorff, L.; Spiess, V.

    2003-12-01

    We used transient numerical simulations of coupled heat and fluid transport to quantify relations between fluid fluxes, basement permeability, and the vigor of local convection on seafloor heat flow patterns adjacent to a basement outcrop through which warm hydrothermal fluids are discharged. These finite-element models are designed to replicate conditions near the Baby Bare outcrop on 3.5-Ma seafloor on the eastern flank of the Juan de Fuca Ridge, where 5-20 L/s of warm fluid seeps from the seafloor. Several transects of heat flow observations co-located along seismic reflection profiles around this feature provide observational constraints for the models. Heat flow is not greatly influenced by venting at the outcrop at distances of several kilometers from the point of sediment onlap, but values rise abruptly immediately adjacent to the outcrop. The model domain consisted of a 21 km x 5 km radial grid, with 8 sedimentary and 6 basalt units, and a characteristic node spacing of 20-500 meters. Conductive simulations include a small rise in heat flow near the outcrop as a result of conductive refraction, but the magnitude of the rise is much smaller than observed. Additional simulations were run using elevated basement thermal conductivity as a proxy for local convection, to evaluate the vigor of local convection required to generate large increases in heat flow near the outcrop. Nusselt numbers (the ratio of heat transported within the edifice by conduction and advection to that which would be transported by conduction alone) of 100 < Nu < 1000 are required in order to homogenize temperatures along the sediment-basement interface and closely match the observed heat flow profile. Interestingly, it is not necessary to vent any fluid at the outcrop to generate this pattern; local convection is sufficient. Fully-coupled simulations were run with fluid forced from the seamount at 5-20 L/s. We find that local convection occurs within the seamount in cases with

  7. All-sky Meteor Orbit System AMOS and preliminary analysis of three unusual meteor showers

    NASA Astrophysics Data System (ADS)

    Tóth, Juraj; Kornoš, Leonard; Zigo, Pavol; Gajdoš, Štefan; Kalmančok, Dušan; Világi, Jozef; Šimon, Jaroslav; Vereš, Peter; Šilha, Jiří; Buček, Marek; Galád, Adrián; Rusňák, Patrik; Hrábek, Peter; Ďuriš, František; Rudawska, Regina

    2015-12-01

    All-sky Meteor Orbit System (AMOS) is a semi-autonomous video observatory for detection of transient events on the sky, mostly the meteors. Its hardware and software development and permanent placement on several locations in Slovakia allowed the establishment of Slovak Video Meteor Network (SVMN) monitoring meteor activity above the Central Europe. The data reduction, orbital determination and additional results from AMOS cameras - the SVMN database - as well as from observational expeditions on Canary Islands and in Canada provided dynamical and physical data for better understanding of mutual connections between parent bodies of asteroids and comets and their meteoroid streams. We present preliminary results on exceptional and rare meteor streams such as September ɛ Perseids (SPE) originated from unknown long periodic comet on a retrograde orbit, suspected asteroidal meteor stream of April α Comae Berenicids (ACO) in the orbit of meteorites Příbram and Neuschwanstein and newly observed meteor stream Camelopardalids (CAM) originated from Jupiter family comet 209P/Linear.

  8. Analysis of historical meteor and meteor shower records: Korea, China, and Japan

    NASA Astrophysics Data System (ADS)

    Yang, Hong-Jin; Park, Changbom; Park, Myeong-Gu

    2005-05-01

    We have compiled and analyzed historical Korean meteor and meteor shower records in three Korean official history books, Samguksagi which covers the three Kingdoms period (57 B.C.-A.D. 935), Goryeosa of Goryeo dynasty (A.D. 918-1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392-1910). We have found 3861 meteor and 31 meteor shower records. We have confirmed the peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids, or Leonids through the Monte Carlo test. The peaks persist from the period of Goryeo dynasty to that of Joseon dynasty, for almost one thousand years. Korean records show a decrease of Perseids activity and an increase of Orionids/north-Taurids/Leonids activity. We have also analyzed seasonal variation of sporadic meteors from Korean records. We confirm the seasonal variation of sporadic meteors from the records of Joseon dynasty with the maximum number of events being roughly 1.7 times the minimum. The Korean records are compared with Chinese and Japanese records for the same periods. Major features in Chinese meteor shower records are quite consistent with those of Korean records, particularly for the last millennium. Japanese records also show Perseids feature and Orionids/north-Taurids/Leonids feature, although they are less prominent compared to those of Korean or Chinese records.

  9. ROAN Remote radio meteor detection sensor

    NASA Astrophysics Data System (ADS)

    Lesanu, C. E.

    2016-01-01

    Only few meteor enthusiasts across the world today, approaches systematically the radio meteor detection technique, one of the reasons being the difficulty to build and install proper permanent antennas, especially when low-VHF frequency opportunity transmitters are used as illuminators. Other reasons were in the past the relatively high cost of the entire system, receivers and computers, and not ultimately the high power consumption of the system in a 24/7 operation, when using regular personal computers. The situation changed in the recent years with the advent of the low cost software defined radio SDR receivers and low consumption/cost single board computers SBC. A commercial off-the-shelf hardware based remote radio meteor detection sensor is presented.

  10. Microbial community on oceanic ferro-manganese crusts from Takuyo-Daigo Seamount and Ryusei Seamount

    NASA Astrophysics Data System (ADS)

    Nitahara, S.; Kato, S.; Yamagishi, A.

    2012-12-01

    Background and Purpose Iron and manganese oxide deposits are often found on deep seafloor. Rocks covered with these oxides are called ferro-manganese crusts (Mn crusts), and are ubiquitously distributed on deep seafloor (Rona 2003). Because Mn crusts contain rare metals such as Co, Pt and rare earth element, it can be resources in the future. Mn crusts and microbes on Mn crusts may contribute to material, especially carbon and nitrogen circulation between hydrosphere and lithosphere. Mechanism of Mn crust formation is not completely understood. Wang et al. propose a model that microorganisms associate with initial Mn mineral deposition (Wang et al., 2011). There is a possibility that microbes may contribute to formation of Mn crust relying on their ability to oxidize Fe and Mn. However, there is limited information about diversity, spatial distribution and abundance of microbes on Mn crust surface. Our purpose is to clarify microbial community composition, spatial distribution, diversity and abundance of microbes on Mn crusts collected from Takuyo-Daigo seamount and Ryusei seamount. Method We collected Mn crusts, sediments and ambient seawater from Takuyo-Daigo seamount at the depth of 1200 m, 1419 m, 2209 m and 2991 m during NT09-02 cruise in Feb 2009 and Ryusei seamount at the depth of 1194 m, 2079 m during KY11-02 in Feb 2011 with remotely operated vehicle Hyper-Dolphin (JAMSTEC). Genomic DNA was extracted from each sample using Fast DNA kit for soil (Qbiogene). Partial 16S rRNA gene and amoA gene were amplified by PCR with prokaryote-universal primer set (Uni516F-Uni1407R) and bacterial and archaeal amoA specific primer sets. PCR products were cloned. The nucleotide sequences of randomly selected clones were determined. We performed phylogenetic and statistical analysis to determine microbial community compositions, and estimated diversity indices. We also estimated the copy numbers of 16S rRNA and amoA genes of Bacteria and Archaea by quantitative PCR. Results

  11. Topographically induced circulation patterns and mixing over Condor seamount

    NASA Astrophysics Data System (ADS)

    Bashmachnikov, I.; Loureiro, C. M.; Martins, A.

    2013-12-01

    Analysis of mean and oscillatory circulation patterns over Condor seamount, situated near the central group of the Azores islands, was performed. During 1.5 years of observations, at least half of the time an anticyclonic cap was established over the summit. The vortex was characterised by a strong asymmetry: it was shifted to the south of the summit and strongly stretched along the gentle eastern and western slopes of the seamount.

  12. Knut Lundmark, meteors and an early Swedish crowdsourcing experiment.

    PubMed

    Kärnfelt, Johan

    2014-10-01

    Mid twentieth century meteor astronomy demanded the long-term compilation of observations made by numerous individuals over an extensive geographical area. Such a massive undertaking obviously required the participation of more than just professional astronomers, who often sought to expand their ranks through the use of amateurs that had a basic grasp of astronomy as well as the night sky, and were thus capable of generating first-rate astronomical reports. When, in the 1920s, renowned Swedish astronomer Knut Lundmark turned his attention to meteor astronomy, he was unable to rely even upon this solution. In contrast to many other countries at the time, Sweden lacked an organized amateur astronomy and thus contained only a handful of competent amateurs. Given this situation, Lundmark had to develop ways of engaging the general public in assisting his efforts. To his advantage, he was already a well-established public figure who had published numerous popular science articles and held talks from time to time on the radio. During the 1930s, this prominence greatly facilitated his launching of a crowdsourcing initiative for the gathering of meteor observations. This paper consists of a detailed discussion concerning the means by which Lundmark's initiative disseminated astronomical knowledge to the general public and encouraged a response that might directly contribute to the advancement of science. More precisely, the article explores the manner in which he approached the Swedish public, the degree to which that public responded and the extent to which his efforts were successful. The primary aim of this exercise is to show that the apparently recent Internet phenomenon of 'crowdsourcing', especially as it relates to scientific research, actually has a pre-Internet history that is worth studying. Apart from the fact that this history is interesting in its own right, knowing it can provide us with a fresh vantage point from which to better comprehend and appreciate

  13. The Radio Meteor Zoo: a citizen science project

    NASA Astrophysics Data System (ADS)

    Calders, S.; Verbeeck, C.; Lamy, H.; Martínez Picar, A.

    2016-01-01

    Scientists from the BRAMS radio meteor network have started a citizen science project called Radio Meteor Zoo in collaboration with Zooniverse in order to identify meteor reflections in BRAMS spectrograms. First, a small-scale version of the Radio Meteor Zoo was carried out with a sample of meteor identifications in 12 spectrograms by 35 volunteers. Results are presented here and allowed us to define a method that reliably detects meteor reflections based on the identifications by the volunteers. It turns out that, if each spectrogram is inspected by 10 volunteers, hit and false detection percentages of 95% respectively 6% are expected. The Radio Meteor Zoo is online at https://www.zooniverse.org/projects/zooniverse/radio-meteor-zoo. Citizen scientists are kindly invited to inspect spectrograms.

  14. Exploring the relationship between meteor parameters based on photographic data

    NASA Astrophysics Data System (ADS)

    Yancheva, Y.; Hristova, S.; Bojurova, E.

    2016-01-01

    The paper presents an attempt to investigate the relationship between the luminosity and the linear length of the meteors, based on photographic observations of the Geminid meteor shower during the night of maximum in December 2015.

  15. Radar Observations of Meteor Interactions in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Mann, I.; Pellinen-Wannberg, A.; Tjulin, A.

    2011-12-01

    Solid particles entering the Earth's atmosphere produce meteors in the ionosphere, typically at 80 to 120 km altitude, but also beyond. The major process causing the meteor is the vaporization of the solid after heating by collision with the atmospheric particles; sputtering also occurs. A fraction of the material that is ablated from the entering objects re-condenses into meteoric smoke particles. Meteors are actively detected by backscattering of radar signals and they are observed, for instance, with the EISCAT (European Incoherent Scatter Scientific Association) radars. Meteor trail and headecho observations detect the ionisation that is associated with the meteor. They allow for studying the properties of the entering solid objects (dust and meteors) and the subsequent ionospheric interactions. We discuss the range of objects that can be detected with EISCAT and the capability of the measurements to find the formation of the meteoric smoke. We then consider the possibilities for measurements with the future EISCAT 3D.

  16. Trophodynamic studies on the Condor seamount (Azores, Portugal, North Atlantic)

    NASA Astrophysics Data System (ADS)

    Colaço, A.; Giacomello, E.; Porteiro, F.; Menezes, G. M.

    2013-12-01

    Compared to the surrounding ocean waters, seamounts are commonly considered habitats where biological productivity is higher and consumers proliferate. Despite their high productivity, studies of seamount trophic webs are still scarce and fragmentary, and little is known about the connections between the different compartments. What are the trophic interactions of seamount fauna? How do the pelagic and benthic environment couple? In order to answer these questions, stable isotopes δ15N and δ13C were measured in the organisms collected during the course of numerous campaigns at the Condor seamount in the North Atlantic. The Condor seamount food chain is composed of five trophic levels. Mesopelagic organisms are the link between the epipelagic environment and the benthic and benthopelagic organisms, bridging the gap between primary consumers and the 4th and 5th trophic chain levels. Our results demonstrate, through stable isotope analysis, the important role of mesopelagic organisms in the transfer of energy within the seamount food web, as modeling/theoretical studies have previously suggested.

  17. Otolith chemistry reveals seamount fidelity in a deepwater fish

    NASA Astrophysics Data System (ADS)

    Régnier, Thomas; Augley, Julian; Devalla, Sandhya; Robinson, Craig D.; Wright, Peter J.; Neat, Francis C.

    2017-03-01

    There are thousands of seamounts (underwater mountains) throughout the world's deep oceans, many of which support diverse faunal communities and valuable fish stocks. Although seamounts are often geographically and bathymetrically isolated from one another, it is not clear how biologically isolated they are from one another. We analysed the chemical signature of the otoliths of a deepwater fish, the roundnose grenadier (Coryphaenoides rupestris) to test the null hypothesis that there is random exchange between individuals from a seamount and other adjacent areas. The fish were sampled on the Scottish west coast, from the Rosemary Bank seamount and two adjacent locations of similar depth, in the same year at roughly the same time of year. We used flow-injection inductively coupled plasma mass spectrometry to measure trace element concentrations from micro-milled portions of the otolith corresponding to adult and juvenile life history stages. The elemental signatures of the fish from the seamount were distinguishable from the fish from the two other areas during both the juvenile and adult life-history phase. We infer that once juveniles settle on the seamount they remain there for the rest of their lives. Evidence for population structure should be factored into exploitation strategies to prevent local depletion and is an important consideration with respect to Rosemary bank being included in a network of Marine Protected Areas around Scotland.

  18. Infrasonic Tracking of the Chelyabinsk Meteor

    NASA Astrophysics Data System (ADS)

    Garces, M. A.; Smirnov, A.; Liszka, L.

    2013-12-01

    The Infrasonic Energy, Nth Octave (INFERNO) energy estimator of Garces (2013) is used in conjunction with the PMCC4 array processing algorithm to refine the chronology and energetics of infrasonic signals from the Chelyabinsk Meteor. We concentrate on infrasound array data from the closest stations: I31KZ (Aktyubinsk, Kazakhstan), I43RU (Dubna, Russia), and KURK (Kurchatov, Kazakhstan), using the published satellite trajectory as a starting point. This study systematically applies standardized, self-similar, logarithmic time-frequency multiresolution algorithms to infrasonic data with the aim of improving the temporal and spatial resolution of the arrivals associated with the meteor's impact.

  19. Meteor spectra from AMOS video system

    NASA Astrophysics Data System (ADS)

    Rudawska, Regina; Tóth, Juraj; Kalmančok, Dušan; Zigo, Pavol; Matlovič, Pavol

    2016-04-01

    Here we demonstrate the capability of the updated All-Sky Meteor Orbit System (AMOS) (called AMOS-Spec) to measure the main element abundances of meteors. The AMOS-Spec program has been created with the intention of carrying out regular systematic spectroscopic observations. At the same time, the meteoroid trajectory and pre-atmospheric orbit are independently measured from data collected by the AMOS camera network. This, together with spectral information, allows us to find the link between the meteoroid and its parent body, from both dynamical and physical consideration. Here we report results for 35 selected cases.

  20. Antarctic ozone - Meteoric control of HNO3

    NASA Technical Reports Server (NTRS)

    Prather, Michael J.; Rodriguez, Jose M.

    1988-01-01

    Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.

  1. In Situ Measurements of Meteoric Ions

    NASA Technical Reports Server (NTRS)

    Grebowsky, Joseph M.; Aiken, Arthur C.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Extraterrestrial material is the source of metal ions in the Earth's atmosphere, Each year approx. 10(exp 8) kg of material is intercepted by the Earth. The origin of this material is predominantly solar orbiting interplanetary debris from comets or asteroids that crosses the Earth's orbit. It contains a very small amount of interstellar material. On occasion the Earth passes through enhanced amounts of debris associated with the orbit of a decaying comet. This leads to enhanced meteor shower displays for up to several days. The number flux of shower material is typically several times the average sporadic background influx of material. Meteoric material is some of the earliest material formed in the solar system. By studying the relative elemental abundances of atmospheric metal ions, information can be gained on the chemical composition of cometary debris and the chemical makeup of the early solar system. Using in situ sampling with rocket-borne ion mass spectrometers; there have been approximately 50 flights that made measurements of the metal ion abundances at attitudes between 80 and 130 km. It is this altitude range where incoming meteoric particles am ablated, the larger ones giving rise to visible meteor. displays. In several rocket measurements isotopic ratios of different atomic ion mass components and metal molecular ion concentrations have been determined and used to identify unambiguously the measured species and to investigate the processes controlling the metal ion distributions The composition of the Earth's ionosphere was first sampled by an ion mass spectrometer flown an a rocket in 1956. In 1958 a rocket-borne ion spectrometer identified, fbr the first time, a layer of metal ions near 95 km. These data were interpreted as evidence of an extraterrestrial rather than a terrestrial source. Istomin predicted: "It seems probable that with some improvement in the method that analysis of the ion composition in the E-region may be used for determining

  2. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This book contains lesson plans that provide an integrated approach to incorporating Great Lakes environmental issues into elementary subjects. The book is divided into three subject areas: (1) History, which includes the origins of the Great Lakes, Great Lakes people, and shipwrecks; (2) Social Studies, which covers government, acid rain as a…

  3. Determination of meteor flux distribution over the celestial sphere

    NASA Technical Reports Server (NTRS)

    Andreev, V. V.; Belkovich, O. I.; Filimonova, T. K.; Sidorov, V. V.

    1992-01-01

    A new method of determination of meteor flux density distribution over the celestial sphere is discussed. The flux density was derived from observations by radar together with measurements of angles of arrival of radio waves reflected from meteor trails. The role of small meteor showers over the sporadic background is shown.

  4. Easy way to estimate meteor brightness on TV frames

    NASA Astrophysics Data System (ADS)

    Leonov, V. A.; Bagrov, A. V.

    2016-01-01

    The traditional method of the meteor brightness measurements claims that the meteor brightness is equal to the stellar magnitude of a star that looks like a meteor in the brightest point of its track. This rule was convenient for the comparison of meteor observations by different observers and for the analysis of the brightness distributions of meteors from observed showers. This traditional method suffers from systematic errors, particularly those that arise from using stellar brightness measured in specific spectral wave bands different from the observer's ones, but mainly due to neglecting the influence of the meteor angular velocity on the real meteor brightness. To get a proper estimate of the meteor brightness that is a measure of the ground meteor illumination in the non-systematic units, an observer must take into account that the effective exposition of a meteor image in any resolution element of its track is a few times shorter than the corresponding exposition of a star image in the same frame. We propose a very simple method for improved estimations of meteor brightness by applying a correction to the meteor stellar magnitude obtained within the traditional framework.

  5. A parent body search across several video meteor data bases

    NASA Astrophysics Data System (ADS)

    Šegon, D.; Gural, P.; Andreić, Ž.; Skokić, I.; Korlević, K.; Vida, D.; Novoselnik, F.

    2014-07-01

    A meteor stream search that uses all the known near-Earth objects (NEOs) as parent bodies, with their individual orbital elements as the starting point, has found statistically significant associations when applied to video meteor data bases. By using the combined CMN-SonotaCo data sets containing 133,652 video meteor orbits, 30 comets were associated with meteor showers of which only 23 were previously listed in the IAU MDC data base. Additionally, 43 asteroids with inclinations over 15 degrees may be associated to streams containing ten or more meteor orbits, each possibly representing a new meteor shower. Lastly, by using a modified search that compared the orbital similarity of each meteor to all other video meteors in the data base, 1093 groupings with more than ten meteors were found that may be indicative of several new minor showers. Of those groups, 6 new showers were found to be potentially associated to a parent body. Several dozen additional groups are planned for publication and submittal to the IAU for their consideration as newly discovered streams. Altogether 56,486 (42%) of the meteors in the combined video meteor data base are in one of the meteor stream groupings found, while the rest are likely sporadics. Further analysis is needed to prove that the groupings found are indeed minor showers.

  6. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  7. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  8. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  9. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  10. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  11. The activity of autumn meteor showers in 2006-2008

    NASA Astrophysics Data System (ADS)

    Kartashova, Anna

    2015-03-01

    The purpose of meteor observations in INASAN is the study of meteor showers, as the elements of the migrant substance of the Solar System, and estimation of risk of hazardous collisions of spacecrafts with the particles of streams. Therefore we need to analyze the meteor events with brightness of up to 8 m, which stay in meteoroid streams for a long time and can be a hazardous for the spacecraft. The results of our single station TV observations of autumn meteor showers for the period from 2006 to 2008 are presented. The high-sensitive hybrid camera (the system with coupled of the Image Intensifier) FAVOR with limiting magnitude for meteors about 9m. . .10m in the field of view 20 × 18 was used for observations. In 2006-2008 from October to November more than 3 thousand of meteors were detected, 65% from them have the brightness from 6m to 9m. The identification with autumn meteor showers (Orionids, Taurids, Draconids, Leonids) was carried out. In order to estimate the density of the influx of meteor matter to the Earth for these meteor showers the Index of meteor activity (IMA) was calculated. The IMA distribution for the period 2006 - 2008 is given. The distributions of autumn meteor showers (the meteors with brightness of up to 8 m) by stellar magnitude from 2006 to 2008 are also presented.

  12. Meteor Search by Spirit, Sol 668

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Annotated Meteor Search by Spirit, Sol 668

    The panoramic cameras on NASA's Mars Exploration Rovers are about as sensitive as the human eye at night. The cameras can see the same bright stars that we can see from Earth, and the same patterns of constellations dot the night sky. Scientists on the rover team have been taking images of some of these bright stars as part of several different projects. One project is designed to try to capture 'shooting stars,' or meteors, in the martian night sky. 'Meteoroids' are small pieces of comets and asteroids that travel through space and eventually run into a planet. On Earth, we can sometimes see meteoroids become brilliant, long 'meteors' streaking across the night sky as they burn up from the friction in our atmosphere. Some of these meteors survive their fiery flight and land on the surface (or in the ocean) where, if found, they are called 'meteorites.' The same thing happens in the martian atmosphere, and Spirit even accidentally discovered a meteor while attempting to obtain images of Earth in the pre-dawn sky back in March, 2004 (see http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html, and Selsis et al. (2005) Nature, vol 435, p. 581). On Earth, some meteors come in 'storms' or 'showers' at predictable times of the year, like the famous Perseid meteor shower in August or the Leonid meteor shower in November. These 'storms' happen when Earth passes through the same parts of space where comets sometimes pass. The meteors we see at these times are from leftover debris that was shed off of these comets.

    The same kind of thing is predicted for Mars, as well. Inspired by calculations about Martian meteor storms by meteor scientists from the University of Western Ontario in Canada and the Centre de Recherche en Astrophysique de Lyon in France, and also aided by other meteor research colleagues from NASA's Marshall Space Flight Center, scientists on

  13. Origins of nonvolcanic seamounts in a forearc environment

    NASA Astrophysics Data System (ADS)

    Fryer, Patricia; Fryer, Gerard J.

    The outer half of the Mariana forearc, the region between the trench axis and the active volcanic arc, contains numerous large seamounts formed entirely by nonvolcanic processes. These seamounts are up to 30 km in diameter and rise as much as 2 km from the seafloor around them. Within about 50 km of the trench axis most of the seamounts are horst blocks of uplifted forearc material. From 50 to about 120 km from the trench axis the seamounts are either sites of updomed forearc material caused by diapiric intrusion, or sites of extrusion of diapirically emplaced serpentinized ultra manes fiom the lower crust/upper mantle of the underlying forearc. The formation of the diapiric material comprising these seamounts is dependent on the evolution of the thermal structure of the shallow (above 30 km) portion of the overriding plate as a convergence zone develops. Changes in the thermal structure influence the distribution of the stability fields of various regional metamorphic facies within the forearc region. As a convergence zone evolves, the greenschist stability field retreats from the region of the trench axis and is replaced by the stability field of the lawsonite-albite-chlorite facies at shallow levels, and by that of the the blueschist facies at depth. The disappearance of the greenschist facies stability field from the forearc suggests that the serpentinite diapirs are either emplaced early in the history of the forearc or that serpentinite remains metastable within the outer forearc for tens of millions of years. The growth of the chlorite and blueschist stability fields may explain the apparent capacity of forearc regions to accommodate large amounts of fluids driven off the downgoing slab by compaction, desiccation, and dehydration reactions. Although conditions appropriate for the formation of either fault block seamounts or diapirically formed seamounts may exist in any forearc, the occurrence of the seamounts is dependent on the local tectonic environment

  14. Meteor Shower Activity Derived from "Meteor Watching Public-Campaign" in Japan

    NASA Technical Reports Server (NTRS)

    Sato, M.; Watanabe, J.

    2011-01-01

    We tried to analyze activities of meteor showers from accumulated data collected by public campaigns for meteor showers which were performed as outreach programs. The analyzed campaigns are Geminids (in 2007 and 2009), Perseids (in 2008 and 2009), Quadrantids (in 2009) and Orionids (in 2009). Thanks to the huge number of reports, the derived time variations of the activities of meteor showers is very similar to those obtained by skilled visual observers. The values of hourly rates are about one-fifth (Geminids 2007) or about one-fourth (Perseids 2008) compared with the data of skilled observers, mainly due to poor observational sites such as large cities and urban areas, together with the immature skill of participants in the campaign. It was shown to be highly possible to estimate time variation in the meteor shower activity from our campaign.

  15. Crustal deformation dynamics and stress evolution during seamount subduction: High-resolution 3-D numerical modeling

    NASA Astrophysics Data System (ADS)

    Ruh, Jonas B.; Sallarès, Valentí; Ranero, César R.; Gerya, Taras

    2016-09-01

    Seamounts or submarine volcanoes frequently collide with the overriding crust along presently active subduction zones locally modifying stress and permanent deformation patterns. Dynamics of this process is not fully understood, and several end-member scenarios of seamount-crust interaction are proposed. Here we use high-resolution 3-D numerical models to investigate evolution of crustal deformation and stress distribution within the upper plate induced by the underthrusting of subducting seamounts. The dynamical effects of the upper plate strength, subduction interface strength, and strain weakening of the crust are investigated. Experiment results demonstrate that characteristic crustal fracturing patterns formed in response to different seamount-crust interaction scenarios. Indenting seamounts strongly deform the overriding plate along a corridor as wide as the underthrusting seamount by constantly shifting subvertical shear zones rooted at the seamount extensions. A reentrant develops during initial seamount collision. A topographic bulge atop the seamount and lateral ridges emerge from further seamount subduction. Obtained stress pattern shows areas of large overpressure above the rearward and large underpressure above the trenchward flank of the seamount. Results of numerical experiments are consistent with seismic reflection images and seismic velocity models of the upper plate in areas of seamount subduction along the Middle America Trench and give important insights into the long-lasting question, whether subducting seamounts and rough seafloor act as barriers or asperities for megathrust earthquakes.

  16. Automated Meteor Fluxes with a Wide-Field Meteor Camera Network

    NASA Technical Reports Server (NTRS)

    Blaauw, R. C.; Campbell-Brown, M. D.; Cooke, W.; Weryk, R. J.; Gill, J.; Musci, R.

    2013-01-01

    Within NASA, the Meteoroid Environment Office (MEO) is charged to monitor the meteoroid environment in near ]earth space for the protection of satellites and spacecraft. The MEO has recently established a two ]station system to calculate automated meteor fluxes in the millimeter ]size ]range. The cameras each consist of a 17 mm focal length Schneider lens on a Watec 902H2 Ultimate CCD video camera, producing a 21.7 x 16.3 degree field of view. This configuration has a red ]sensitive limiting meteor magnitude of about +5. The stations are located in the South Eastern USA, 31.8 kilometers apart, and are aimed at a location 90 km above a point 50 km equidistant from each station, which optimizes the common volume. Both single station and double station fluxes are found, each having benefits; more meteors will be detected in a single camera than will be seen in both cameras, producing a better determined flux, but double station detections allow for non ]ambiguous shower associations and permit speed/orbit determinations. Video from the cameras are fed into Linux computers running the ASGARD (All Sky and Guided Automatic Real ]time Detection) software, created by Rob Weryk of the University of Western Ontario Meteor Physics Group. ASGARD performs the meteor detection/photometry, and invokes the MILIG and MORB codes to determine the trajectory, speed, and orbit of the meteor. A subroutine in ASGARD allows for the approximate shower identification in single station meteors. The ASGARD output is used in routines to calculate the flux in units of #/sq km/hour. The flux algorithm employed here differs from others currently in use in that it does not assume a single height for all meteors observed in the common camera volume. In the MEO system, the volume is broken up into a set of height intervals, with the collecting areas determined by the radiant of active shower or sporadic source. The flux per height interval is summed to obtain the total meteor flux. As ASGARD also

  17. The radiant distribution of AMOR radar meteors

    NASA Astrophysics Data System (ADS)

    Galligan, D. P.; Baggaley, W. J.

    2005-05-01

    A large data set provided by the highly sensitive Advanced Meteor Orbit Radar (AMOR) facility is used to investigate the structure of the sporadic meteor complex. The helion, antihelion and apex apparent sources are clearly found. Observational bias is then removed to reveal the true source distributions as observed on Earth. A long-standing problem in meteor science has been the difference in observed meteor flux between the helion and antihelion source directions. Consideration of the effects of atmospheric interference and Faraday rotation is found to lead to a closer balance between these. The orbital distributions present within the different regions are also discussed. The apex region is found to have a strong retrograde component and a weaker prograde component that exists at high southerly latitudes and that contains orbits with particularly high inclinations. The retrograde component reduces substantially after inclusion of observational bias corrections. Care should be taken in comparing the results presented here with those from other radar systems: AMOR is sensitive to dust as small in diameter as ~40μm, while the limiting sensitivity of most contemporary systems is an order of magnitude larger.

  18. BRAMS --- the Belgian RAdio Meteor Stations

    NASA Astrophysics Data System (ADS)

    Lamy, H.; Ranvier, S.; Martinez Picar, A.; Gamby, E.; Calders, S.; Anciaux, M.; De Keyser, J.

    2014-07-01

    BRAMS is a new radio observing facility developed by the Belgian Institute for Space Aeronomy (BISA) to detect and characterize meteors using forward scattering. It consists of a dedicated beacon located in the south-east of Belgium and in 25 identical receiving stations spread over the Belgian territory. The beacon transmits a pure sinusoidal wave at a frequency of 49.97 MHz with a power of 150 watts. A complete description of the BRAMS network and the data produced will be provided. The main scientific goals of the project are to compute fluxes, retrieve trajectories of individual objects, and determine physical parameters (speed, ionization, mass) for some of the observed meteor echoes. All these goals require a good knowledge of the radiation patterns of the transmitting and receiving antennas. Simulations have been made and will be validated with in-situ measurements using a UAV/drone equipped with a transmitter flying in the far-field region. The results will be provided. Each receiving station generates around 1 GB of data per day with typical numbers of sporadic meteor echoes of 1500--2000. An automatic detection method of these meteor echoes is therefore mandatory but is complicated by spurious echoes mostly due to airplanes. The latest developments of this automatic detection method will be presented and compared to manual counts for validation. Strong and weak points of the method will be presented as well as a possible alternative method using neural networks.

  19. Lake Erie Fireball Meteor, Orangeville View

    NASA Video Gallery

    This brief video shows a view of the Aug 8 fireball meteor that entered the atmosphere 54 miles above Lake Erie and moved SSE at 25 km/s, or 55,900 mph. This view is from the all sky camera in Oran...

  20. Lake Erie Fireball Meteor, Tavistock View

    NASA Video Gallery

    This brief video shows a view of the Aug 8 fireball meteor that entered the atmosphere 54 miles above Lake Erie and moved SSE at 25 km/s, or 55,900 mph. This view is from the all sky camera in Tavi...

  1. Bright Meteor Lights Up Atlanta Skies

    NASA Video Gallery

    This video shows a very bright meteor that streaked over the skies of Atlanta, Ga., on the night of Aug. 28, 2011. The view is from an all sky camera in Cartersville, Ga., operated by NASA’s Mars...

  2. Lake Erie Fireball Meteor, Mcmaster View

    NASA Video Gallery

    This brief video shows a view of the Aug 8 fireball meteor that entered the atmosphere 54 miles above Lake Erie and moved SSE at 25 km/s, or 55,900 mph. This view is from the all sky camera in Mcma...

  3. Meteor Search by Spirit, Sol 668

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Annotated Meteor Search by Spirit, Sol 668

    The panoramic cameras on NASA's Mars Exploration Rovers are about as sensitive as the human eye at night. The cameras can see the same bright stars that we can see from Earth, and the same patterns of constellations dot the night sky. Scientists on the rover team have been taking images of some of these bright stars as part of several different projects. One project is designed to try to capture 'shooting stars,' or meteors, in the martian night sky. 'Meteoroids' are small pieces of comets and asteroids that travel through space and eventually run into a planet. On Earth, we can sometimes see meteoroids become brilliant, long 'meteors' streaking across the night sky as they burn up from the friction in our atmosphere. Some of these meteors survive their fiery flight and land on the surface (or in the ocean) where, if found, they are called 'meteorites.' The same thing happens in the martian atmosphere, and Spirit even accidentally discovered a meteor while attempting to obtain images of Earth in the pre-dawn sky back in March, 2004 (see http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html, and Selsis et al. (2005) Nature, vol 435, p. 581). On Earth, some meteors come in 'storms' or 'showers' at predictable times of the year, like the famous Perseid meteor shower in August or the Leonid meteor shower in November. These 'storms' happen when Earth passes through the same parts of space where comets sometimes pass. The meteors we see at these times are from leftover debris that was shed off of these comets.

    The same kind of thing is predicted for Mars, as well. Inspired by calculations about Martian meteor storms by meteor scientists from the University of Western Ontario in Canada and the Centre de Recherche en Astrophysique de Lyon in France, and also aided by other meteor research colleagues from NASA's Marshall Space Flight Center, scientists on

  4. Luceafarul: a Romanian meteor-inspired poem.

    NASA Astrophysics Data System (ADS)

    McBeath, A.; Ghoerghe, A. D.

    1999-10-01

    The poem Luceafarul, written by Mihai Eminescu and first published in 1883, is considered as being the greatest Romanian poetic masterpiece. In commemorating the 110th anniversary of the author's death in 1999, the authors present here a short discussion of the poem's astronomical imagery, which includes the re-using of long-held beliefs about meteors from old Romanian myths and folklore.

  5. Geochemical Evolution of the Louisville Seamount Chain

    NASA Astrophysics Data System (ADS)

    Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; Lonsdale, P. F.

    2007-12-01

    The Louisville seamount chain is a 4300 km long chain of submarine volcanoes in the southwestern Pacific that is commonly thought to represent a hotspot track. It spans an ~80 Myr age range, comparable to that of the Hawaiian-Emperor chain (Koppers et al., G-cubed, 5 (6), 2004). The few previously dredged igneous samples are dominantly basaltic and alkalic, and have been inferred to represent post-shield volcanism (Hawkins et al., AGU Monograph, 43, 235, 1987). Their isotope and trace element signatures suggest an unusually homogenous mantle source (Cheng et al., AGU Monograph, 43, 283, 1987). Dredging in 2006, during the AMAT02RR cruise of the R.V. Revelle, was carried out in the hope of recovering both shield and post-shield samples and of exploring the geochemical evolution of the chain. Igneous rocks were recovered from 33 stations on 23 seamounts covering some 47 Myr of the chain's history. Our study, focusing on the major and trace element and Sr, Nd and Pb isotopic characteristics of these samples, shows that all are alkalic basalts, basanites and tephrites containing normative nepheline. Variations in major and trace elements appear to be controlled predominantly by variable extents of melting and fractional crystallization, with little influence from mantle source heterogeneity. Indeed, age-corrected isotopic values define only a narrow range, in agreement with long-term source homogeneity relative to the scale of melting; e.g., ɛNd varies from +4.1 to +5.7, 206Pb/204Pb from 19.048 to 19.281, and 87Sr/86Sr from 0.70362 to 0.70398. These values broadly fall within the fields of the proposed "C" or "FOZO" mantle end-members. However, small variations are present, with less radiogenic Nd and Pb isotope ratios at the older, western end of the chain, defining a trend toward a broadly EM2-like composition. Although some workers have postulated that the Louisville hotspot was the source of the ~120 Myr Ontong Java Plateau, our samples are isotopically distinct

  6. Spectral analysis of four meteors. [chemical compositions and spectral emissions

    NASA Technical Reports Server (NTRS)

    Harvey, G. A.

    1973-01-01

    Four meteor spectra are analyzed for chemical composition and radiative processes. The chemical compositions of the Taurid, Geminid, and Perseid meteors were found to be similar to that of a typical stony meteorite. The chemical composition of the sporadic meteor was found to be similar to that of a nickel iron meteorite. The radiation from optical meteors was found to be similar to that of a low temperature gas, except that strong, anomalous ionic radiation is superposed on the neutral radiation in bright, fast meteors.

  7. Meteor Beliefs Project: meteoritic weapons

    NASA Astrophysics Data System (ADS)

    Kristine Larsen, K.; McBeath, A.

    2012-01-01

    A discussion of meteoritic iron weapons and weapon-like tools is given, drawing on fictional, mythological, and real-world examples. The evidence suggests that no great significance was attached to such metal purely because of its "heavenly" provenance prior to the early 19th century AD, despite later assumptions, including during the period of increased interest in meteorites, cratering events and the early usage of meteoritic iron, beginning in the early 20th century.

  8. Comparison of TV magnitudes and visual magnitudes of meteors

    NASA Astrophysics Data System (ADS)

    Shigeno, Yoshihiko; Toda, Masayuki

    2008-08-01

    The generally accepted belief is that a meteor, with a large amount of infrared rays, can be captured brighter than it actually is by infrared-sensitive image intensifiers (I.I.) or CCD. We conducted observations of meteors using three methodologies: 1) I.I. with an attached filter that has the same spectral response as the human eye at night vision, 2) I.I. without the filter and 3) visually to determine meteor magnitudes. A total of 31 members of the astronomical club at Meiji University observed 50 Perseid meteors, 19 Geminid meteors as well as 44 sporadic meteors and the results were tabulated. The results helped us understand that on average I.I. can record meteors as brighter than visual observation by the magnitude equivalent of 0.5 for Perseids, 1.0 for Geminids and 0.5 for sporadic meteors. For I.I. with a filter that has the same spectral response the human eye at night vision, it turned out that we could obtain almost the same magnitude with observation by the human eye. We learned that a bright meteor with negative magnitude can be observed by I.I. brighter than the human eye. From several examples, we found I.I. could record a meteor with about -1 visual magnitude as brighter by about three magnitudes. We could probably do so because a bright meteor with negative magnitude may contain more infrared rays and the brightness could be amplified.

  9. Physical and dynamical studies of meteors. [radar observation of fragmentation

    NASA Technical Reports Server (NTRS)

    Southworth, R. B.; Sekanina, Z.

    1974-01-01

    Distribution of meteors in streams detected in the synoptic-year meteor sample plus a study of the fragmentation characteristics of the synoptic-year meteor sample are presented. Population coefficients and dispersion coefficients were determined for each meteor stream. These two parameters serve to determine the number of definite members of the stream in the sample used, and to estimate the actual space density of meteor streams. From results of the fragmentation study, it appears that the main body of most radar meteors does not ablate fragments layer by layer, but collapses rather suddenly under dynamic pressures on the order of 0,0002 dynes/cm. Furthermore, it is believed that fragmentation does not cause a serious selection effect in the radar meteor data.

  10. The Census of Marine Life on Seamounts: results from a global science program

    NASA Astrophysics Data System (ADS)

    Stocks, K.; Clark, M.; Rowden, A.; Consalvey, M.

    2010-12-01

    CenSeam (a Global Census of Marine Life on Seamounts) is a network of more than 500 scientists, policy makers and conservationists around the world. These participants are collaborating to increase our understanding of the factors driving seamount community composition and diversity, such that we can better understand and manage the effects of human activities. The major scientific outcomes of the CenSeam community include the findings that 1) Seamount community composition is often similar to surrounding habitats; however, community structure can be different. 2) Contrary to conventional wisdom, few seamounts follow island biogeography predictions. 3) Seamounts can support a higher benthic biomass than surrounding habitats. 4) Seamounts can support species and communities new to science, and represent range extensions for known species, which are being described from CenSeam voyages. 5) For the first time, the extent of the vulnerability and risk to seamount benthic communities from fishing has been quantified. 6) Whilst long assumed, CenSeam researchers have demonstrated that seamount communities are disturbed by fishing and are slow to recover. And 7) Seamounts might act as repositories of biodiversity during future periods of extreme environmental change, as they have likely done in the past. The major products of Censeam include 1) a book synthesizing seamount knowledge: Seamounts: Ecology, Fisheries and Conservation (from Blackwell Publishing); 2) a recent review of the structure and function of seamount benthic communities, human impacts, and seamount management and conservation (Ann Rev Mar Sci); 3) hundreds of scientific publications, including Special Issues in Marine Ecology and Oceanography (in collaboration with the Seamount Biogeogsciences Network), and a Special Collection in PLoSONE; 4) guidance documents and formal advising for seamount management communities, including the United Nations Environment Program, International Seabed Authority

  11. Results of Lunar Impact Observations During Geminid Meteor Shower Events

    NASA Technical Reports Server (NTRS)

    Suggs, R. J.; Suggs, R. M.

    2015-01-01

    the lunar environment associated with larger lunar impactors, but also provides statistical data for verification and improving meteoroid prediction models. Current meteoroid models indicate that the Moon is struck by a sporadic meteoroid with a mass greater than 1 kg over 260 times per year. This number is very uncertain since observations for objects in this mass range are few. Factors of several times, higher or lower, are easily possible. Meteor showers are also present to varying degrees at certain times of the year. The Earth experiences meteor showers when encountering the debris left behind by comets, which is also the case with 2 the Moon. During such times, the rate of shower meteoroids can greatly exceed that of the sporadic background rate for larger meteoroids. Looking for meteor shower impacts on the Moon at about the same time as they occur on Earth will yield important data that can be fed into meteor shower forecasting models, which can then be used to predict times of greater meteoroid hazard on the Moon. The Geminids are one such meteor shower of interest. The Geminids are a major meteor shower that occur in December with a peak intensity occurring usually during the 13th and 14th of the month and appearing to come from a radiant in the constellation Gemini. The Geminids are interesting in that the parent body of the debris stream is an asteroid, which along with the Quadrantids, are the only major meteor showers not originating from a comet. The Geminids parent body, 3200 Phaethon, is about 5 km in diameter and has an orbit that has a 22deg inclination which intersects the main asteroid belt and has a perihelion less than half of Mercury's perihelion distance. Thus, its orbit crosses those of Mars, Earth, Venus, and Mercury. The Geminid debris stream is by far the most massive as compared to the others. When the Earth passes through the stream in mid-December, a peak intensity of approx. equal 120 meteors per hour can be seen. Because of the

  12. Observed deep energetic eddies by seamount wake.

    PubMed

    Chen, Gengxin; Wang, Dongxiao; Dong, Changming; Zu, Tingting; Xue, Huijie; Shu, Yeqiang; Chu, Xiaoqing; Qi, Yiquan; Chen, Hui

    2015-11-30

    Despite numerous surface eddies are observed in the ocean, deep eddies (a type of eddies which have no footprints at the sea surface) are much less reported in the literature due to the scarcity of their observation. In this letter, from recently collected current and temperature data by mooring arrays, a deep energetic and baroclinic eddy is detected in the northwestern South China Sea (SCS) with its intensity, size, polarity and structure being characterized. It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s). The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy. More observations suggest that the deep eddy should not be an episode in the area. Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

  13. Observed deep energetic eddies by seamount wake

    NASA Astrophysics Data System (ADS)

    Chen, Gengxin; Wang, Dongxiao; Dong, Changming; Zu, Tingting; Xue, Huijie; Shu, Yeqiang; Chu, Xiaoqing; Qi, Yiquan; Chen, Hui

    2015-11-01

    Despite numerous surface eddies are observed in the ocean, deep eddies (a type of eddies which have no footprints at the sea surface) are much less reported in the literature due to the scarcity of their observation. In this letter, from recently collected current and temperature data by mooring arrays, a deep energetic and baroclinic eddy is detected in the northwestern South China Sea (SCS) with its intensity, size, polarity and structure being characterized. It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s). The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy. More observations suggest that the deep eddy should not be an episode in the area. Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

  14. Observed deep energetic eddies by seamount wake

    PubMed Central

    Chen, Gengxin; Wang, Dongxiao; Dong, Changming; Zu, Tingting; Xue, Huijie; Shu, Yeqiang; Chu, Xiaoqing; Qi, Yiquan; Chen, Hui

    2015-01-01

    Despite numerous surface eddies are observed in the ocean, deep eddies (a type of eddies which have no footprints at the sea surface) are much less reported in the literature due to the scarcity of their observation. In this letter, from recently collected current and temperature data by mooring arrays, a deep energetic and baroclinic eddy is detected in the northwestern South China Sea (SCS) with its intensity, size, polarity and structure being characterized. It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s). The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy. More observations suggest that the deep eddy should not be an episode in the area. Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport. PMID:26617343

  15. Great Lakes: Great Gardening.

    ERIC Educational Resources Information Center

    New York Sea Grant Inst., Albany, NY.

    This folder contains 12 fact sheets designed to improve the quality of gardens near the Great Lakes. The titles are: (1) "Your Garden and the Great Lakes"; (2) "Organic Gardening"; (3) "Fruit and Vegetable Gardening"; (4) "Composting Yard Wastes"; (5) "Herbicides and Water Quality"; (6)…

  16. Dredged trachyte and basalt from kodiak seamount and the adjacent aleutian trench, alaska.

    PubMed

    Forbes, R B; Hoskin, C M

    1969-10-24

    Blocky fragments of aegirine-augite trachyte (with accompanying icerafted gravels.) were recovered from the upper slopes of Kodiak Seamount in several dredge hauls. An alkali basalt pillow segment was also dredged from a moatlike depression, at a depth of 5000 meters, near the west base of the seamount. These retrievals confirm the volcanic origin of Kodiak Seamount and further support the view of Engel, Engel, and Havens that the higher elevations of seamounts are composed of alkali basalts or related variants.

  17. Dynamics of Dust Particles Released from Oort Cloud Comets and Their Contribution to Radar Meteors

    NASA Technical Reports Server (NTRS)

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Janches, Diego

    2012-01-01

    The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D < or approx. 10 microns are blown out from the solar system by radiation pressure, while those with D > or approx. 1 mm have a very low Earth-impact probability. The intermediate particle sizes, D approx. 100 microns represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a approx. 1 AU. They are expected to produce meteors with radiants near the apex of the Earth s orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e approx. 1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.

  18. DYNAMICS OF DUST PARTICLES RELEASED FROM OORT CLOUD COMETS AND THEIR CONTRIBUTION TO RADAR METEORS

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Janches, Diego

    2011-12-10

    The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D {approx}< 10 {mu}m are blown out from the solar system by radiation pressure, while those with D {approx}> 1 mm have a very low Earth-impact probability. The intermediate particle sizes, D {approx} 100 {mu}m, represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a {approx} 1 AU. They are expected to produce meteors with radiants near the apex of Earth's orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e {approx} 1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.

  19. Meteoroids, Meteors, and the Near-Earth Object Impact Hazard

    NASA Astrophysics Data System (ADS)

    Chapman, Clark R.

    2008-06-01

    In considering the modern-day hazard from infalling near-Earth asteroids and comets, the focus has shifted toward the smallest, most frequent impacts that can do damage on the ground, like the 1908 Tunguska aerial burst. There is considerable uncertainty about the potential for damage by objects in the range 20 to 100 m diameter. Since smaller, less dangerous, meter-sized meteoroids are part of a continuum of small interplanetary bodies, derived by a collisional cascade and Yarkovsky spin-up, research on such phenomena by meteor scientists can shed light on a vital question that will soon have great practical relevance as new telescopic searches for near-Earth asteroids come on line: what is the threshold size between harmless high-altitude airbursts and impacts that can cause lethal damage on the ground?

  20. Meteor velocity distribution and an optimum monitoring mathematical model

    NASA Technical Reports Server (NTRS)

    Volkov, N. G.; Salimov, O. N.

    1987-01-01

    At present, there are a great number of radio meteor, ionosphere and rocket observation data for the altitude range of 80 to 100 km which indicate the existence of large scale circulation systems in the mesopause to low thermosphere range which change regularly with season and latitude. But the existing observation network and observation programs are not optimal for revealing the main factors forming the circulation mode at these altitudes. A generalized optimum monitoring mathematical model is offered for consideration. The model input data are distribution density, response function, individual measurement root mean square uncertainty and detection effectiveness function. The model makes it possible to obtain the observation distribution density, the minimal possible dispersion and optimized system effectiveness.

  1. Residency and spatial use by reef sharks of an isolated seamount and its implications for conservation.

    PubMed

    Barnett, Adam; Abrantes, Kátya G; Seymour, Jamie; Fitzpatrick, Richard

    2012-01-01

    Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (~14 km away) and one grey reef shark completed a round trip of ~250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef.

  2. Residency and Spatial Use by Reef Sharks of an Isolated Seamount and Its Implications for Conservation

    PubMed Central

    Barnett, Adam; Abrantes, Kátya G.; Seymour, Jamie; Fitzpatrick, Richard

    2012-01-01

    Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (∼14 km away) and one grey reef shark completed a round trip of ∼250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef. PMID:22615782

  3. Interferometric Meteor Head Echo Observations using the Southern Argentina Agile Meteor Radar (SAAMER)

    NASA Technical Reports Server (NTRS)

    Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C; Michell, R.; Samara, M.

    2013-01-01

    A radar meteor echo is the radar scattering signature from the free-electrons in a plasma trail generated by entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head-echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF meteor radars (often called all-sky1radars) primarily detect the specular reflection of meteor trails traveling perpendicular to the line of sight of the scattering trail, while High Power and Large Aperture (HPLA) radars efficiently detect meteor head-echoes and, in some cases, non-specular trails. The fact that head-echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are very sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. In addition, the fact that the simultaneous detection of all different scattering mechanisms can be made with the same instrument, rather than requiring assorted different classes of radars, can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER) deployed at the Estacion Astronomica Rio Grande (EARG) in Tierra del Fuego, Argentina. The results presented here are derived from observations performed over a period of 12 days in August 2011, and include meteoroid dynamical parameter distributions, radiants and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

  4. Double station observation of Draconid meteor outburst from two moving aircraft

    NASA Astrophysics Data System (ADS)

    Koten, Pavel; Vaubaillon, Jeremie; Margonis, Anastasios; Tóth, Juraj; Ďuriš, František; McAulliffe, Jonathan; Oberst, Jürgen

    2015-12-01

    A Draconid meteor shower outburst was observed from the boards of two scientific aircraft on 8 October 2011. In this paper we report the results of this double station experiment. The beginning and terminal heights are similar to other Draconid observations and confirm the fragile nature of the meteoroids. From the distribution function of terminal heights, a critical mass was found to be about 3.5 g. A behaviour of the terminal heights changes at this point. Light curves of Draconid meteors show great variability with a maximum of the F-number distribution around 0.35, which also confirms fragility of the material. Observed radiants of the meteors are in agreement with the theoretical model. Although encounters with two different filaments were predicted, it is impossible to distinguish between them from the radiants as well as the orbital data. Despite the complications with the data processing the airborne mission shows that such double station experiment is possible and provides valuable insight into meteor structure and dynamics.

  5. Geophysical exploration of the Southeast Tyrrhenian Sea (Italy): Seamounts batimetries

    NASA Astrophysics Data System (ADS)

    Passaro, Salvatore; Milano, Girolamo

    2010-05-01

    The Tyrrhenian Sea is a young extensional basin in the Central Mediterranean that formed within a complex convergent boundary between Africa and Eurasian Plates. Its opening, associated to the west dipping subduction of the Ionian lithosphere, started about 11 My ago and was marked first by an EW and successively by an ESE directed extension. This last mainly affected the Southeast Tyrrhenian Sea and led to the formation of the Marsili ocean-like basin. This large-scale extension produced the onset of volcanism throughout the Tyrrhenian Sea and the formation of several seamounts. High values of heat flow (>150 mW m-2) and the thin crust (7 km on average) and lithosphere (30 km on average) testify the young age of formation of oceanic crust in the Southeast Tyrrhenian Sea. On November 2007, a multidisciplinary oceanographic survey was carried out in the Southeast Tyrrhenian Sea by a group of researchers of the IAMC-CNR (Naples), Osservatorio Vesuviano (INGV, Naples), NOAA (Seattle) and GNS (New Zealand) on board of the R/V Urania. The main aim of the survey was the identification and the exploration of potential active volcanic and/or hydrothermal vents on the seamounts located in the Southeast Tyrrhenian Sea. Twelve Tyrrhenian seamounts have been explored with a modified CTD system, in order to acquire "tow-yo" profiles in dynamic mode (real time monitoring of physical and chemical parameters of seawater along vertical/horizontal profiles). In addiction, Multibeam swath bathymetry was carried out over fifteen seamounts. The strategy for the achieving of the aim consisted in two phases: i) row multibeam acquisition of the sea floor morphology to verify, confirm or review all available data, ii) tow-yo activity and seawater sampling. Here, we show the main results of bathymetric data acquisition carried out over fifteen seamounts with the use of the Reson Seabat 8160 multibeam sonar system mounted on keel of the R/V Urania. The most interesting morphostructural

  6. Internal tidal currents over the summit of cross seamount

    USGS Publications Warehouse

    Noble, M.; Mullineaux, L.S.

    1989-01-01

    Spectral analysis of 46 days of record from a current meter deployed above the summit of Cross Seamount (approximately 300 km west of the Hawaiian Islands) indicates that the strongest current fluctuations were driven by the semidiurnal tide. The tides accounted for 28% of the variance in the current spectrum, were mainly baroclinic in character, and were propagated towards the west-northwest. The amplitude of the S2 current flowing parallel to the major axis of the current ellipse ranged between 4 and 9 cm-1 s. The S2 current was 1.5 times larger than the M2 current. This ratio is 4 times larger than is expected for this region of the Pacific and is not a general characteristics of flows over seamounts. Instantaneous current speeds over the seamount often exceeded 20 cm s-1 and were probably responsible for the small ripples observed on the sediment-covered regions of the summit. ?? 1990.

  7. Data processing of records of meteoric echoes

    NASA Astrophysics Data System (ADS)

    Dolinský, P.

    2016-01-01

    The data obtained in the period from 4 November 2014 to 31 July 2014 by our receiving and recording system was statistically processed. The system records meteoric echoes from the TV transmitter Lviv 49.739583 MHz (N49.8480° E24.0369°, Ukraine) using a 4-element Yagi antenna with horizontal polarization (elevation of 0° and azimuth of 60°), receiver ICOM R-75 in the CW mode, and a computer with a recording using HROFFT v1.0.0f. The main goal was to identify weak showers in these data. Mayor or strong showers are visible without processing (referred at IMC2015, Mistelbach). To find or to identify weaker showers is more difficult. Not all echoes are meteoric echoes, but also ionospheric echoes or lightning disturbances are present.

  8. The cometary and asteroidal origins of meteors

    NASA Technical Reports Server (NTRS)

    Kresak, L.

    1973-01-01

    A quantitative examination of the gravitational and nongravitational changes of orbits shows that for larger interplanetary bodies the perturbations by Jupiter strongly predominate over all other effects, which include perturbations by other planets, splitting of comet nuclei and jet effects of cometary ejections. The structure of meteor streams, indicates that the mutual compensation of the changes in individual elements entering the Jacobian integral, which is characteristic for the comets, does not work among the meteoroids. It appears that additional forces of a different kind must exert appreciable influence on the motion of interplanetary particles of meteoroid size. Nevertheless, the distribution of the Jacobian constant in various samples of meteor orbits furnishes some information on the type of their parent bodies and on the relative contribution of individual sources.

  9. A fireball analysis from Spanish meteor observations

    NASA Astrophysics Data System (ADS)

    Benítez Sánchez, O.; Ocaña González, F.

    2004-03-01

    Naked eye meteor records from Spain are used for an analysis of 3240 fireballs reported by members of the Sociedad de Observadores de Meteoros Y Cometas de España (SOMYCE) and by casual eye-witnesses from 1982 to 2000. This analysis concerns various areas, such as statistical studies of the colours and the frequency of fireballs in annual meteor showers. Annual and diurnal variations are also discussed. We describe the population index r for magnitudes brighter than m=-2 for ORI, VIR, AQU, TAU, CAP, QUA, GEM, LYR, LEO, KCG, PER and sporadic fireballs. The typical population index is always in the range ≃ 1.2 to 1.9, except for Perseids and Geminids. An investigation of visual fireballs radiants was attempted with the Radiant software. The sample of fireballs (282 fireballs with the path reported) only shows evidence for the Perseids and Leonids.

  10. An FDTD model of scattering from meteor head plasma

    NASA Astrophysics Data System (ADS)

    Marshall, R. A.; Close, S.

    2015-07-01

    We have developed a three-dimensional finite difference time domain (FDTD) model of scattering of radar waves from meteor head plasma. The model treats the meteor head plasma as a cold, collisional, and magnetized plasma, and solves Maxwell's equations and the Langevin equation simultaneously and self-consistently in and around the plasma. We use this model to investigate scattering of radar waves from a meteor head (the "head echo") under a range of plasma densities, meteor scale sizes, and wave frequencies. In this way we relate the radar cross section (RCS) to these variable parameters. We find that computed RCS disagrees with previous analytical theory at certain meteor sizes and densities, in some cases by over an order of magnitude. We find that the calculated meteor head RCS is monotonically related to the "overdense area" of the meteor, defined as the cross-section area of the part of the meteor where the plasma frequency exceeds the wave frequency. These results provides a physical measure of the meteor size and density that can be inferred from measured RCS values from ground-based radars. Meteoroid mass can then be inferred from the meteor plasma distribution using established methods.

  11. Radar and Meteors: Controversy over the Origin of Meteors in Postwar Astronomy

    NASA Astrophysics Data System (ADS)

    Sullivan, Woodruff T., III

    2006-12-01

    After World War II radio physicists and engineers discovered that radar reflections were readily obtained off the ionized trails left by meteors. The group led by Bernard Lovell at the Jodrell Bank Experimental Station of Manchester University, England, led the effort to design radar transmitters, receivers, and antenna systems that could better understand these reflections. First, an entire suite of daytime meteor showers was found to accompany the familiar nighttime showers. Next, associating with meteor astronomers such as Fred Whipple, Ernst Öpik, and Cuno Hoffmeister, Lovell found that his radar data could contribute to a longstanding controversy in the field: was there any portion of the meteors whose speeds indicated that they were on hyperbolic orbits and therefore of interstellar origin (i.e., >72 km/s), or did all meteoroids originate within the solar system? By 1953 the Jodrell Bank radar astronomers’ huge samples of echoes and measured speeds of meteors indicated that there were in fact no interstellar interlopers. This settled the question for most workers in the field, although Opik and Hoffmeister did not give in.

  12. Caldera Formation on the Vance Seamounts

    NASA Astrophysics Data System (ADS)

    Clague, D.; Paduan, J.; Cousens, B.; Cornejo, L.; Perfit, M.; Wendt, R.; Stix, J.; Helo, C.

    2006-12-01

    The Vance Seamounts are a chain of near-ridge volcanoes located just west of the southern Juan de Fuca Ridge. The six volcanoes are built on ocean crust ranging from 0.78 Ma at the southeastern end to 2.55 Ma in the northwest. Morphologic analysis indicates that the volcanoes were constructed sequentially and get younger to the southeast towards the ridge axis. Like many near-ridge volcanoes, some of the Vance Seamounts have large offset calderas that presumably formed above evacuated shallow magma chambers within the upper ocean crust. In summer 2006, we completed 6 dives using MBARI's ROV Tiburon to study the formation of these calderas. The floor of each caldera consists of flat-lying volcaniclastite, under about 25 cm of pelagic sediment. Some caldera floors have mounds of post-caldera pillow flows. The caldera walls have a lower section covered by talus and an upper section of interbedded massive flows with columnar joints (to 11 m thick) and pillow basalts. The top of each caldera wall has a unit of volcanic mudstone to sandstone ranging from 20 cm to 2 m thick. The fine matrix of many of these samples is green hydrothermal clay. The finest siltstone to mudstone samples appear to be layers of massive tan hydrothermal clays. Talus fragments, lava and volcaniclastite outcrops are universally coated and cemented by 1 to 4 cm-thick deposits of hydrothermal Mn-oxide crusts, even on the youngest of the volcanoes. Volcanic particles in the sandstones are mostly dense angular glass, but bubble-wall fragments (limu o Pele) are present and indicate formation during low-energy pyroclastic eruptions. Without the few percent limu o Pele fragments, the glass fragments would resemble those inferred to form by quench granulation. We suggest that quench granulation is actually pyroclastic fragmentation that occurs as coalesced magmatic gas bubbles disrupt the molten lava surface at the vents. Our observations confirm that the more southeasterly offset calderas truncated thick

  13. Structural peculiarities of the Quadrantid meteor shower

    NASA Technical Reports Server (NTRS)

    Isamutdinov, Sh. O.; Chebotarev, R. P.

    1987-01-01

    Systematic radio observations to investigate the Quadrantid meteor shower structure are regularly carried out. They have now been conducted annually in the period of its maximum activity, January 1 to 6, since 1966. The latest results of these investigations are presented, on the basis of 1981 to 1984 data obtained using new equipment with a limiting sensitivity of +7.7 sup m which make it possible to draw some conclusions on the Quadrantids shower structure both for transverse and lengthwise directions.

  14. The danger to satellites from meteor storms

    NASA Astrophysics Data System (ADS)

    Beech, M.; Brown, P.; Jones, J.; Webster, A. R.

    During past meteor storms impact probabilities of between 1 and 0.01 percent have be realized per 50m^2 of exposed surface area at altitudes corresponding to both GEO and LEO. The most likely meteoroid stream to yield a storm in the near future is that of the Leonids. Numerical simulations of the orbital evolution of hypothetical Leonid stream meteoroids suggest that storms may occur in the years 1999 and 2000.

  15. A global atmospheric model of meteoric iron

    NASA Astrophysics Data System (ADS)

    Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Höffner, Josef; Yi, Fan; Plane, John M. C.

    2013-08-01

    The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

  16. Meteor showers on the Earth from sungrazers

    NASA Astrophysics Data System (ADS)

    Sekhar, A.; Asher, D.

    2014-07-01

    1. C/2012 S1 (ISON) and C/1680 V1 (Newton's comet): Only very few past works [1,2,3] have looked into the aspects of meteor phenomena from sungrazing comets. Here we study whether feasible meteoroid ejection velocities in ISON and Newton's comet could bring the nodes close to the Earth's orbit so as to cause a visually spectacular meteor shower. Detailed analysis using Lagrange's planetary equations [4] shows that even at very high ejection velocities (˜ 1 km/s), the descending nodes of the meteoroids reach only 0.91 au (quite close to the Earth's orbit; which in itself is very rare for sungrazing orbits) in the case of ISON. For Newton's comet, the required ejection velocities are about 800 m/s for the descending node to reach 1 au. Such high ejection velocities are practically rare for big meteoroids (˜ 1 mm in diameter) which encounter Earth and hence spectacular visual meteor activity can be ruled out completely [5]. 2. Marsden Group versus other Sungrazing Families: A similar analysis using Lagrange's equations [6,7] was done on all the known sungrazing families [8]. We find that, only in the Marsden family, it could lead to substantial nodal dispersion in meteoroids so that the descending nodes can encounter Earth at ejection velocities of the order of few 100 m/s. This matches with the earlier significant works [1,2,9] which linked the Daytime Arietids (ARI) to the Marsden group. The fact that only a very small number of sungrazing orbits favour Earth intersection at low ejection velocities (out of the observed families so far) stands as the primary reason for the absence of regular meteor showers from them although sungrazers in itself are very frequent.

  17. Impact mechanics at Meteor Crater, Arizona

    USGS Publications Warehouse

    Shoemaker, Eugene Merle

    1959-01-01

    Meteor Crator is a bowl-shaped depression encompassed by a rim composed chiefly of debris stacked in layers of different composition. Original bedrock stratigraphy is preserved, inverted, in the debris. The debris rests on older disturbed strata, which are turned up at moderate to steep angles in the wall of the crater and are locally overturned near the contact with the debris. These features of Meteor Crater correspond closely to those of a crater produced by nuclear explosion where depth of burial of the device was about 1/5 the diameter of the resultant crater. Studies of craters formed by detonation of nuclear devices show that structures of the crater rims are sensitive to the depth of explosion scaled to the yield of the device. The structure of Meteor Crater is such as would be produced by a very strong shock originating about at the level of the present crater floor, 400 feet below the original surface. At supersonic to hypersonic velocity an impacting meteorite penetrates the ground by a complex mechanism that includes compression of the target rocks and the meteorite by shock as well as hydrodynamic flow of the compressed material under high pressure and temperature. The depth of penetration of the meteorite, before it loses its integrity as a single body, is a function primarily of the velocity and shape of the meteorite and the densities and equations of state of the meteorite and target. The intensely compressed material then becomes dispersed in a large volume of breccia formed in the expanding shock wave. An impact velocity of about 15 km/sec is consonant with the geology of Meteor Crater in light of the experimental equation of state of iron and inferred compressibility of the target rocks. The kinetic energy of the meteorite is estimated by scaling to have been from 1.4 to 1.7 megatons TNT equivalent.

  18. A Global Atmospheric Model of Meteoric Iron

    NASA Technical Reports Server (NTRS)

    Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Hoffner, Josef; Yi, Fan; Plane, John M. C.

    2013-01-01

    The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

  19. Development of a melting model for meteors

    NASA Astrophysics Data System (ADS)

    Dias, Bruno; Bariselli, Federico; Turchi, Alessandro; Frezzotti, Aldo; Chatelain, Philippe; Magin, Thierry

    2016-11-01

    Meteor phenomenon is a frequent event happening on planet Earth. Due to the high entry velocities of these objects, the surface of the material undergoes extreme heat loads. Since the material is mainly composed by several oxides, eventually, the surface temperature will overcome the melting point. In this study we propose a melting model, in order to understand the material behavior, coupled with a flow solver. A detailed study of the flow around the stagnation streamline is also presented.

  20. Elementary process and meteor train spectra

    NASA Technical Reports Server (NTRS)

    Ovezgeldyev, O. G.

    1987-01-01

    Mechanisms of excitation of individual spectral line radiation were studied experimentally and theoretically and it was demonstrated that such processes as oxidation, resonant charge exchange, dissociative recombination and others play an important part in the chemistry of excited particles. The foundation was laid toward simulating the elementary processes of meteor physics. Having a number of advantages and possibilities, this method is sure to find a wide use in the future.

  1. Photometric stellar catalogue for TV meteor astronomy

    NASA Astrophysics Data System (ADS)

    Leonov, V. A.; Bagrov, A. V.

    2016-01-01

    Photometry for ordinary astrophysics was carefully developed for its own purposes. As stars radiation is very similar to the blackbody radiation, astronomers measure star illumination in wide or narrow calibrated spectral bands. This is enough for star photometry with precise accuracy and for measuring their light flux in these bands in energetic units. Meteors are moving objects and do not allow collection of more photons then they emit. So meteor observers use the whole spectral band that can be covered by sensitivity of their light sensors. This is why measurements of stellar magnitudes of background stars by these sensors are not the same as catalogued star brightness in standard photometric spectral bands. Here we present a special photometric catalogue of 93 bright non-variable stars of the northern hemisphere, that can be used by meteor observers of standard background whose brightness are calculated in energetic units as well as in non-systematic stellar magnitudes in spectral wavelength of the WATEC 902 sensitivity.

  2. Meteor showers on Earth from sungrazing comets

    NASA Astrophysics Data System (ADS)

    Sekhar, A.; Asher, D. J.

    2014-01-01

    Sungrazing comets have always captured a lot of interest and curiosity among the general public as well as scientists since ancient times. The perihelion passage of comet C/2012 S1 (ISON) at the end of this year (on 2013 November 28) is an eagerly awaited event. In this work, we do a mathematical study to check whether meteoroids ejected from this comet during its journey around the Sun can produce spectacular meteor phenomena on Earth. Our calculations show that although the orbital elements of this comet are much more favourable than for most sungrazers to have its descending node near the Earth's orbit, even ejection velocities as high as 1 km s-1 do not induce sufficient nodal dispersion to bring meteoroids to Earth intersection during present times. A similar result applies to Newton's comet C/1680 V1 which has surprisingly similar orbital elements, although it is known to be a distinct comet from C/2012 S1. Our analysis also shows that for meteoroids ejected from all known sungrazing groups during recent epochs, only the Marsden family (with required ejection velocities of some hundreds of m s-1) can produce meteor phenomena during present times. In a broader sense, we indicate why we do not observe visually brilliant meteor showers from frequently observed sungrazers.

  3. Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on Lo'ihi Seamount and Kilauea Volcano

    USGS Publications Warehouse

    Clague, D.A.; Davis, A.S.; Bischoff, J.L.; Dixon, J.E.; Geyer, R.

    2000-01-01

    Glassy bubble-wall fragments, morphologically similar to littoral limu o Pele, have been found in volcanic sands erupted on Lo'ihi Seamount and along the submarine east rift zone of Kilauea Volcano. The limu o Pele fragments are undegassed with respect to H2O and S and formed by mild steam explosions. Angular glass sand fragments apparently form at similar, and greater, depths by cooling-contraction granulation. The limu o Pele fragments from Lo'ihi Seamount are dominantly tholeiitic basalt containing 6.25-7.25% MgO. None of the limu o Pele samples from Lo'ihi Seamount contains less than 5.57% MgO, suggesting that higher viscosity magmas do not form lava bubbles. The dissolved CO2 and H2O contents of 7 of the limu o Pele fragments indicate eruption at 1200??300 m depth (120??30 bar). These pressures exceed that generally thought to limit steam explosions. We conclude that hydrovolcanic eruptions are possible, with appropriate pre-mixing conditions, at pressures as great as 120 bar.

  4. Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area

    PubMed Central

    Geersen, Jacob; Ranero, César R.; Barckhausen, Udo; Reichert, Christian

    2015-01-01

    To date, the parameters that determine the rupture area of great subduction zone earthquakes remain contentious. On 1 April 2014, the Mw 8.1 Iquique earthquake ruptured a portion of the well-recognized northern Chile seismic gap but left large highly coupled areas un-ruptured. Marine seismic reflection and swath bathymetric data indicate that structural variations in the subducting Nazca Plate control regional-scale plate-coupling variations, and the limited extent of the 2014 earthquake. Several under-thrusting seamounts correlate to the southward and up-dip arrest of seismic rupture during the 2014 Iquique earthquake, thus supporting a causal link. By fracturing of the overriding plate, the subducting seamounts are likely further responsible for reduced plate-coupling in the shallow subduction zone and in a lowly coupled region around 20.5°S. Our data support that structural variations in the lower plate influence coupling and seismic rupture offshore Northern Chile, whereas the structure of the upper plate plays a minor role. PMID:26419949

  5. Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area.

    PubMed

    Geersen, Jacob; Ranero, César R; Barckhausen, Udo; Reichert, Christian

    2015-09-30

    To date, the parameters that determine the rupture area of great subduction zone earthquakes remain contentious. On 1 April 2014, the Mw 8.1 Iquique earthquake ruptured a portion of the well-recognized northern Chile seismic gap but left large highly coupled areas un-ruptured. Marine seismic reflection and swath bathymetric data indicate that structural variations in the subducting Nazca Plate control regional-scale plate-coupling variations, and the limited extent of the 2014 earthquake. Several under-thrusting seamounts correlate to the southward and up-dip arrest of seismic rupture during the 2014 Iquique earthquake, thus supporting a causal link. By fracturing of the overriding plate, the subducting seamounts are likely further responsible for reduced plate-coupling in the shallow subduction zone and in a lowly coupled region around 20.5°S. Our data support that structural variations in the lower plate influence coupling and seismic rupture offshore Northern Chile, whereas the structure of the upper plate plays a minor role.

  6. Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

    NASA Astrophysics Data System (ADS)

    Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C.; Michell, R.; Samara, M.

    2014-03-01

    A radar meteor echo is the radar scattering signature from the free electrons generated by the entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF all-sky meteor radars primarily detect the specular trails, while high-power, large-aperture (HPLA) radars efficiently detect meteor head echoes and, in some cases, nonspecular trails. The fact that head echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. Such systems would also permit simultaneous detection of all different scattering mechanisms using the same instrument, rather than requiring assorted different classes of radars, which can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER). The results presented here are derived from observations performed over a period of 12 days in August 2011 and include meteoroid dynamical parameter distributions, radiants, and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

  7. Diversity and endemism of the benthic seamount fauna in the southwest Pacific.

    PubMed

    de Forges, B R; Koslow, J A; Poore, G C

    2000-06-22

    Seamounts comprise a unique deep-sea environment, characterized by substantially enhanced currents and a fauna that is dominated by suspension feeders, such as corals. The potential importance of these steep-sided undersea mountains, which are generally of volcanic origin, to ocean biogeography and diversity was recognized over 40 years ago, but this environment has remained very poorly explored. A review of seamount biota and biogeography reported a total of 597 invertebrate species recorded from seamounts worldwide since the Challenger expedition of 1872. Most reports, based on a single taxonomic group, were extremely limited: 5 seamounts of the estimated more than 30,000 seamounts in the world's oceans accounted for 72% of the species recorded. Only 15% of the species occurring on seamounts were considered potential seamount endemics. Here we report the discovery of more than 850 macro- and megafaunal species from seamounts in the Tasman Sea and southeast Coral Sea, of which 29-34% are new to science and potential seamount endemics. Low species overlap between seamounts in different portions of the region indicates that the seamounts in clusters or along ridge systems function as 'island groups' or 'chains' leading to highly localized species distributions and apparent speciation between groups or ridge systems that is exceptional for the deep sea. These results have substantial implications for the conservation of this fauna, which is threatened by fishing activity.

  8. Endemicity, biogeograhy, composition, and community structure on a northeast pacific seamount.

    PubMed

    McClain, Craig R; Lundsten, Lonny; Ream, Micki; Barry, James; DeVogelaere, Andrew

    2009-01-01

    The deep ocean greater than 1 km covers the majority of the earth's surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a 'seamount', residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats.

  9. Meteoric water in metamorphic core complexes

    NASA Astrophysics Data System (ADS)

    Teyssier, Christian; Mulch, Andreas

    2015-04-01

    The trace of surface water has been found in all detachment shear zones that bound the Cordilleran metamorphic core complexes of North America. DeltaD values of mica fish in detachment mylonites demonstrate that these synkinematic minerals grew in the presence of meteoric water. Typically deltaD values are very negative (-120 to -160 per mil) corresponding to deltaD values of water that are < -100 per mil given the temperature of water-mica isotopic equilibration (300-500C). From British Columbia (Canada) to Nevada (USA) detachment systems bound a series of core complexes: the Thor-Odin, Valhalla, Kettle-Okanogan, Bitterroot -Anaconda, Pioneer, Raft River, Ruby Mountain, and Snake Range. The bounding shear zones range in thickness from ~100 m to ~1 km, and within the shear zones, meteoric water signature is recognized over 10s to 100s of meters beneath the detachment fault. The age of shearing ranges generally from Eocene in the N (~50-45 Ma) to Oligo-Miocene in the S (25-15 Ma). DeltaD water values derived from mica fish in shear zones are consistent with supradetachment basin records of the same age brackets and can be used for paleoaltimetry if coeval isotopic records from near sea level are available. Results show that a wave of topography (typically 4000-5000 m) developed from N to S along the Cordillera belt from Eocene to Miocene, accompanied by the propagation of extensional deformation and volcanic activity. In addition, each detachment system informs a particular extensional detachment process. For example, the thick Thor-Odin detachment shear zone provides sufficient age resolution to indicate the downward propagation of shearing and the progressive incorporation of footwall rocks into the hanging wall. The Kettle detachment provides a clear illustration of the dependence of fluid circulation on dynamic recrystallization processes. The Raft River system consists of a thick Eocene shear zone that was overprinted by Miocene shearing; channels of meteoric

  10. Weak interplate coupling by seamounts and repeating M approximately 7 earthquakes.

    PubMed

    Mochizuki, Kimihiro; Yamada, Tomoaki; Shinohara, Masanao; Yamanaka, Yoshiko; Kanazawa, Toshihiko

    2008-08-29

    Subducting seamounts are thought to increase the normal stress between subducting and overriding plates. However, recent seismic surveys and laboratory experiments suggest that interplate coupling is weak. A seismic survey in the Japan Trench shows that a large seamount is being subducted near a region of repeating earthquakes of magnitude M approximately 7. Both observed seismicity and the pattern of rupture propagation during the 1982 M 7.0 event imply that interplate coupling was weak over the seamount. A large rupture area with small slip occurred in front of the seamount. Its northern bound could be determined by a trace of multiple subducted seamounts. Whereas a subducted seamount itself may not define the rupture area, its width may be influenced by that of the seamount.

  11. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This booklet introduces an environmental curriculum for use in a variety of elementary subjects. The lesson plans provide an integrated approach to incorporating Great Lakes environmental issues into the subjects of history, social studies, and environmental sciences. Each of these sections contains background information, discussion points, and a…

  12. Multi-Year CMOR Observations of the Geminid Meteor Shower

    NASA Technical Reports Server (NTRS)

    Webster, A. R.; Jones, J.

    2011-01-01

    The three-station Canadian Meteor Orbit Radar (CMOR) is used here to examine the Geminid meteor shower with respect to variation in the stream properties including the flux and orbital elements over the period of activity in each of the consecutive years 2005 2008 and the variability from year to year. Attention is given to the appropriate choice and use of the D-criterion in the separating the shower meteors from the sporadic background.

  13. Theoretical and Observational Studies of Meteor Interactions with the Ionosphere

    DTIC Science & Technology

    2006-06-01

    Spaceborne Ultraviolet 251-384 nm Spectroscopy of a Meteor During the 1997 Leonid Shower , Meteorites and Planetary Science, 37. Jones, W., 1997...RTO-MP-IST-056 12 - 1 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Theoretical and Observational Studies of Meteor Interactions with the...ABSTRACT An intense flux of small-mass meteors has been seen in large-aperture radar scattering for many years. At high altitudes, these meteoroids

  14. Mesospheric observations by a forward scattering meteor radar basic setup

    NASA Astrophysics Data System (ADS)

    Madkour, Waleed; Yamamoto, Masa-yuki

    2016-08-01

    The durations of radio echo signals scattered from meteor ionized trails might not show a consistent increase corresponding to higher density trails due to the rapid removal of meteor ions at certain heights. Several studies have concluded the dominant role of the secondary ozone layer over diffusion in the removal of the meteor trails below 95 km through chemical oxidization of the meteor ions. Using a basic setup configuration of a forward scattering receiver, a trial to observe the mesospheric ozone concentration was performed by analyzing the meteor echo duration distributions. The forward scattered meteor echoes have the advantage of long durations that can enable observing the transition from the diffusion-removal regime to the chemistry-removal regime. The cumulative meteor echo duration distribution of two meteor showers, the Perseids and the Geminids, were analyzed over 10 years and the chemistry-removal regime in each shower was observed. The knee duration position at which a drop in the number of long overdense meteor echoes starts differed by around 30 seconds between the two showers. As the secondary ozone concentration is inversely related to the solar activity level, the Geminids 2011 corresponding to a high solar activity level showed a significant higher counts of long duration echoes compared to the Geminids 2006 during a low activity level, with the knee position shifted to longer duration. The knee positions obtained during the two distinct meteor showers and the two half solar cycle points are generally in agreement with the mesospheric ozone conditions expected in each case. However, continuous data record is required for the other meteor showers and the sporadic meteors at different heights to observe the mesospheric ozone concentration vertically and the full 11-years solar cycle.

  15. Satellite Remote Sensing of Atmospheric Meteoric Ions and Neutral Species

    DTIC Science & Technology

    2006-09-30

    times that of the Mg content. An examination of the content around the times of known meteor showers shows no measurable increases during or following...Fe. The heavy arrows at the bottom of Figure 2 represent the approximate times of major meteor showers . The data are smoothed with a 500 point medium...arrows indicate the times of meteor showers . There are no measurable increases associated with the showers , either at the shower commencement or

  16. The American Meteor Society's filter bank spectroscopy project

    NASA Astrophysics Data System (ADS)

    Gural, P.

    2015-01-01

    The American Meteor Society (AMS) has sponsored the development of an alternative method of meteor spectroscopy that relies on a set of eight very narrow band wavelength filters. The interference filters used are tuned to the dominant meteoric emission lines of Ca+, two Fe line regions, Mg, Na, Si+, the forbidden O line, and atmospheric O777. Discussion will include the design trade-offs, construction of the instrument, first light testing, and initial results.

  17. Diuble station observation of telescopic meteors in Mykolaiv

    NASA Astrophysics Data System (ADS)

    Kulichenko, M. O.; Shulga, O. V.; Sybiryakova, Ye. S.; Kozyryev, Ye. S.

    2017-02-01

    Meteor research using TV CCD unintensified techniques was started in 2011 in Nikolaev astronomical observatory (RI "NAO"). The method of meteor registration is based on the combined observation method developed at RI "NAO". The main accent of the research is made on the precise astrometry and meteoroid orbits calculation. In 2013 first double station meteors with low baseline were observed. Estimation of uncertainties of visible radiant equatorial coordinates, geocentric velocity and heliocentric meteoroid orbit parameters was carried out.

  18. Shigaraki middle and upper atmosphere radar meteor-head-echo database

    NASA Astrophysics Data System (ADS)

    Kero, J.; Nakamura, T.; Szasz, C.; Kastinen, D.; Watanabe, J.; Yamamoto, M.; Fujiwara, Y.; Abo, M.; Tanaka, Y.; Abe, S.

    2014-07-01

    Introduction: Mass infux from space into the terrestrial atmosphere is mainly caused by meteors. Meteors deliver various elements into the atmosphere and the meteoric dust particles are of great importance in the terrestrial atmosphere. For example, they act as nucleus for condensation and clouds and affect various atmospheric phenomena both in physical and chemical aspects. Thus, to investigate the meteor flux, orbits and their interactions in the upper atmosphere is very important but at the same time the method of investigation is limited, especially for precise measurements. High-power large-aperture (HPLA) radar observation is a recent technique to provide useful information on meteor infux and orbits, as well as interactions with the atmosphere. Since 2009 orbital data of about 120,000 meteors [2] have been collected using a novel head-echo analysis algorithm for the lower VHF band [1]. The data was collected using the middle and upper atmosphere radar (MU radar) of Kyoto University at Shigaraki (34.9N, 136.1S). The MU radar is a large atmospheric VHF radar with 46.5 MHz frequency, 1 MW output transmission power and 8330 m^2 aperture array antenna. An open database (MU radar meteor head echo database: MURMHED) for research and education is now being created. Database: The database currently holds 53 different parameters for each event and a number of associated time series consisting of range, height, radar cross section, signal to noise ratio, radial velocity and meteorid velocity. The database parameters are MJD, Year [UT], Month [UT], Day [UT], Hour [UT], Minute [UT], Second [UT], Duration [s], RA [deg], Dec [deg], Az [deg], Ze [deg], Az uncorr [deg], Ze uncorr [deg], Ze correction [deg], Obs initial vel [km/s], Geocentric vel [km/s], RCS [dBsm], SNR [dB], Start hgt [km], End hgt [km], Az of start point [deg], Ze of start point [deg], Az of end point [deg], Ze of end point [deg], Semimajor axis [au], Eccentricity, Perihelion dist [au], Lon of asc node [deg

  19. Optical and Radar Measurements of the Meteor Speed Distribution

    NASA Technical Reports Server (NTRS)

    Moorhead, A. V.; Brown, P. G.; Campbell-Brown, M. D.; Kingery, A.; Cooke, W. J.

    2016-01-01

    The observed meteor speed distribution provides information on the underlying orbital distribution of Earth-intersecting meteoroids. It also affects spacecraft risk assessments; faster meteors do greater damage to spacecraft surfaces. Although radar meteor networks have measured the meteor speed distribution numerous times, the shape of the de-biased speed distribution varies widely from study to study. Optical characterizations of the meteoroid speed distribution are fewer in number, and in some cases the original data is no longer available. Finally, the level of uncertainty in these speed distributions is rarely addressed. In this work, we present the optical meteor speed distribution extracted from the NASA and SOMN allsky networks [1, 2] and from the Canadian Automated Meteor Observatory (CAMO) [3]. We also revisit the radar meteor speed distribution observed by the Canadian Meteor Orbit Radar (CMOR) [4]. Together, these data span the range of meteoroid sizes that can pose a threat to spacecraft. In all cases, we present our bias corrections and incorporate the uncertainty in these corrections into uncertainties in our de-biased speed distribution. Finally, we compare the optical and radar meteor speed distributions and discuss the implications for meteoroid environment models.

  20. METEOR - an artificial intelligence system for convective storm forecasting

    SciTech Connect

    Elio, R.; De haan, J.; Strong, G.S.

    1987-03-01

    An AI system called METEOR, which uses the meteorologist's heuristics, strategies, and statistical tools to forecast severe hailstorms in Alberta, is described, emphasizing the information and knowledge that METEOR uses to mimic the forecasting procedure of an expert meteorologist. METEOR is then discussed as an AI system, emphasizing the ways in which it is qualitatively different from algorithmic or statistical approaches to prediction. Some features of METEOR's design and the AI techniques for representing meteorological knowledge and for reasoning and inference are presented. Finally, some observations on designing and implementing intelligent consultants for meteorological applications are made. 7 references.

  1. Quantifying the direct use value of Condor seamount

    NASA Astrophysics Data System (ADS)

    Ressurreição, Adriana; Giacomello, Eva

    2013-12-01

    Seamounts often satisfy numerous uses and interests. Multiple uses can generate multiple benefits but also conflicts and impacts, calling, therefore, for integrated and sustainable management. To assist in developing comprehensive management strategies, policymakers recognise the need to include measures of socioeconomic analysis alongside ecological data so that practical compromises can be made. This study assessed the direct output impact (DOI) of the relevant marine activities operating at Condor seamount (Azores, central northeast Atlantic) as proxies of the direct use values provided by the resource system. Results demonstrated that Condor seamount supported a wide range of uses yielding distinct economic outputs. Demersal fisheries, scientific research and shark diving were the top-three activities generating the highest revenues, while tuna fisheries, whale watching and scuba-diving had marginal economic significance. Results also indicated that the economic importance of non-extractive uses of Condor is considerable, highlighting the importance of these uses as alternative income-generating opportunities for local communities. It is hoped that quantifying the direct use values provided by Condor seamount will contribute to the decision making process towards its long-term conservation and sustainable use.

  2. Condor seamount (Azores, NE Atlantic): A morpho-tectonic interpretation

    NASA Astrophysics Data System (ADS)

    Tempera, Fernando; Hipólito, Ana; Madeira, José; Vieira, Sara; Campos, Aldino S.; Mitchell, Neil C.

    2013-12-01

    High-resolution datasets collected by multibeam and acoustic backscatter surveys were used to produce fine-scale seafloor nature and morpho-tectonic interpretations of the Condor seamount. Condor constitutes an elongated volcanic ridge that extends for 39 km and rises more than 1800 m from the surrounding seafloor. Constructive morphologies include (i) linear eruptive centres, (ii) volcanic cones with or without summit depressions, (iii) lava flows and (iv) hummocky sectors. Eruptive type is interpreted to vary with depth. On the deeper seamount extremities, the predominance of highly acoustically backscattering volcanic cones and hummocky terrain is interpreted to result from effusive eruptions not yet covered by sediment deposits. In contrast, the smoother relief of the central seamount flanks is interpreted as draping and infilling of the underlying effusive relief by (i) primary volcaniclastic deposits produced by explosive eruptions on the shallowest parts of the ridge, together with (ii) secondary volcanigenic sediments resulting from truncation of the seamount top by swell erosion and (iii) sediments resulting from biogenic production.

  3. Erratic Continental Rocks on Volcanic Seamounts off California and Oregon

    NASA Astrophysics Data System (ADS)

    Paduan, J. B.; Clague, D. A.; Davis, A. S.

    2006-12-01

    The seamounts off the California continental margin, and those well offshore of California and Oregon that formed near mid-ocean ridges, are all constructed of basaltic lava flows and volcanic breccias and sandstones. However, explorations of these seamounts using dredges, and more recently, the remotely operated vehicle Tiburon, frequently recover rocks of a wide assortment of continental lithologies including gabbro, granodiorite, silicic volcanics, limestone, dolomite, and metamorphic rocks. These rocks are often rounded like river and beach cobbles, and the softer rocks are bored as by worms or bivalves. They are covered with manganese oxide crusts of thicknesses that range from a patina to several cm, approaching the thickness on the in-situ basaltic rocks. These rocks are often easier to collect than the basalts. We recognize these rocks to be erratics of continental origin. Erratics have been documented as being transported by icebergs at higher latitudes, but this mechanism is unlikely to be responsible for the erratics we have found as far south as 31.9° N. Three brief papers published by K.O. Emery from 1941 to 1954 proposed that such erratics found in many thick sections of fine-grained sedimentary sequences such as the Monterey Formation, were transported long distances by kelp holdfasts, tree roots, or in the guts of pinnipeds. We propose that these vectors also transport erratics to seamounts, where they have been accumulating since the seamounts formed millions of years ago. Those seamounts that were once islands would have intercepted even more erratics along their shorelines while they stood above sea level. We have recovered or observed such erratics on the Vance Seamounts; Gumdrop, Pioneer, Guide, Davidson, Rodriguez, San Juan, Little Joe, and San Marcos Seamounts; on the muddy bottom of Monterey Bay; and on Northeast Bank and along the Patton Escarpment at the western edge of the California Borderland. These locations are as far as 250 nautical

  4. Mapping AUV Survey of Axial Seamount

    NASA Astrophysics Data System (ADS)

    Thomas, H.; Caress, D.; Conlin, D.; Clague, D.; Paduan, J.; Butterfield, D.; Chadwick, W.; Tucker, P.

    2006-12-01

    In late August and early September 2006, the MBARI Mapping Autonomous Underwater Vehicle (AUV) was deployed for 5 missions on Axial Seamount during a NOAA NeMO cruise on the R/V Thompson. The objective of the survey was to determine the geologic history of the summit of Axial Seamount using high resolution multibeam, sidescan, and sub-bottom profiler data. The Mapping AUV is a torpedo-shaped, 6000 m rated vehicle designed and constructed by MBARI. The vehicle is equipped with a 200 kHz multibeam sonar, 110 kHz and 410 kHz chirp sidescan sonar, and a 2-16 kHz sweep chirp sub-bottom profiler. The multibeam provides a 120-degree swath with 0.94 degree by 0.94 degree beam resolution. The endurance of the AUV is eight hours at 3 knots. Navigation derives from an inertial navigation system (INS) incorporating a ring laser gyro aided by GPS at the surface and by velocity-over- ground observations from a Doppler velocity log (DVL) when within 130 m of the seafloor. A navigational precision of 0.05 percent of distance traveled is achieved with continuous DVL bottom lock. An acoustic modem allows surface aiding of navigation during deep descents. The AUV ran two types of missions: those on the rim of the caldera were run at 90 m altitude with a line spacing of 250 m and those on the caldera floor were run at 50 m altitude with a line spacing of 150 or 175 m. The surveys covered most of 1998 lava flow on the south rim of the caldera and northern part of the south rift zone, the southern region of the caldera floor where hydrothermal vents are common, the northeast rim of the caldera where volcaniclastic deposits related to caldera collapse drape the surface, the north rift zone, and the northern portion of the caldera floor. The low-altitude maps have a resolution of 1 m, so large individual lava pillars and hydrothermal chimneys can be seen, fissures stand out clearly, and the regions of collapsed lobate flows and lava channels are prominent. Many of the flows, including the

  5. Gravimetric determination of densities of seamounts along the Bonin Arc

    NASA Astrophysics Data System (ADS)

    Ishihara, Takemi

    A new term "effective depth" is defined as the water depth including the nonlinear effect on a complete Bouguer correction. A least-squares method is used to determine the densities of seamounts from the linear relationship between free-air anomaly and the effective depth, which is calculated by applying a two-dimensional FFT to the bathymetric data. Densities of 19 seamounts along the Bonin Arc are determined using this least-squares method. For seven seamounts including two calderas and two islands, the densities are recalculated removing gravity effects of simple inner structures, which are inferred from the apparent density variations as functions of search radii. Generally speaking, with a track spacing less than 3 nautical miles and with a range of effective depths greater than 1 km, the densities can be determined with an accuracy of 0.05 g/cc. The determined densities have a wide range from 2.4 to nearly 3.0 g/cc. A relationship is recognized between densities of seamounts and their mean depths: the density increases with the depth and a prominent change in the rate of increase is seen at a depth of about 1 km. This is probably due to a decrease in porosity with increase in the depth. A clear pattern of densities is recognized for seamounts with mean depths of about 2 km: a density lower than 2.67 g/cc corresponds to an andesitic volcano and a density higher than 2.67 g/cc corresponds to a basaltic volcano. Two calderas are associated with high Bouguer anomalies.

  6. Caldera collapse at near-ridge seamounts: an experimental investigation

    NASA Astrophysics Data System (ADS)

    Coumans, Jason P.; Stix, John

    2016-10-01

    Collapse calderas are sub-circular volcanic depressions caused by subsidence of the magma reservoir roof during an eruption. Scaled physical models of caldera collapse using flat topography have been instrumental in investigating the spatial and temporal development of calderas, in particular, two distinctive sets of concentric ring faults, one reverse and one normal. More recent analog studies have investigated the effect of non-flat topography which alters the principle stress trajectories and resulting collapse structure. This work provides the basis for investigating how naturally scaled topographic loads may affect caldera collapse in relation to shallow magma reservoirs. The objective of this study is to understand how a near-ridge seamount affects caldera collapse from both a central and offset position as the seamount migrates above the magma reservoir as a result of plate motion. We utilize scaled analog models of caldera collapse in conjunction with three-dimensional (3D) laser scanning and digital particle image velocimetry (DPIV) to investigate caldera collapse dynamics at near-ridge seamounts. Experiments using a seamount cone positioned centrally above the magma reservoir result in (1) increased subsidence along the interior outward-dipping faults and (2) a preference to more symmetric collapse patterns as indicated by the subsidence profile and structure of the caldera relative to experiments with an offset cone. When the cone is offset, the collapse is asymmetric and trapdoor in nature, with the center of greatest subsidence displaced away from the region of largest topographic load. For these latter experiments, subsidence is focused where the roof is thinnest along an initial reverse fault, followed by a transition to an antithetic graben structure. The asymmetric collapse in the experiments results in a caldera with a tilted profile. Offset calderas at near-ridge seamounts are tilted towards the ridge axis, suggesting that they may have collapsed

  7. Present State and Prospects for the Meteor Research in Ukraine

    NASA Astrophysics Data System (ADS)

    Shulga, O.; Voloshchuk, Y.; Kolomiyets, S.; Cherkas, Y.; Kimakovskay, I.; Kimakovsky, S.; Knyazkova, E.; Kozyryev, Y.; Sybiryakova, Y.; Gorbanev, Y.; Stogneeva, I.; Shestopalov, V.; Kozak, P.; Rozhilo, O.; Taranukha, Y.

    2015-03-01

    ODESSA. Systematical study of the meteor events are being carried out since 1953. In 2003 complete modernization of the observing technique was performed, and TV gmeteor patrolh on the base of WATEC LCL902 cameras was created. @ wide variety of mounts and objectives are used: from Schmidt telescope F = 540 mm, F/D = 2.25 (field of view FOV = (0.68x0.51) deg, star limiting magnitude SLM = 13.5 mag, star astrometric accuracy 1-2 arcsec) up to Fisheye lenses F = 8 mm, F/D = 3.5 (FOV = (36x49) deg, SLM = 7 mag). The database of observations that was collected between 2003 and 2012 consists of 6176 registered meteor events. Observational programs on basis and non-basis observations in Odessa (Kryzhanovka station) and Zmeiny island are presented. Software suite of 12 programs was created for processing of meteor TV observations. It enables one to carry out the whole cycle of data processing: from image preprocessing up to orbital elements determination. Major meteor particles research directions: statistic, areas of streams, precise stream radiant, orbit elements, phenomena physics, flare appearance, wakes, afterglow, chemistry and density. KYIV. The group of meteor investigations has been functioning more than twenty years. The observations are carried out simultaneously from two points placed at the distance of 54 km. Super-isocon low light camera tubes are used with photo lens: F = 50mm, F/D = 1.5 (FOV = (23.5 x 19.0) deg, SLM = 9.5 mag), or F = 85, F/D = 1.5 (FOV = (13x11) deg, SLM = 11.5 mag). Astrometry, photometry, calculation of meteor trajectory in Earth atmosphere and computation of heliocentric orbit are realized in developed gFalling Starh software. KHARKOV. Meteor radio-observations have begun in 1957. In 1972, the radiolocation system MARS designed for automatic meteor registration was recognized as being the most sensitive system in the world. With the help of this system 250 000 faint meteors (up to 12 mag) were registered between 1972 and 1978 (frequency

  8. Meteor Beliefs Project: Meteoric imagery associated with the death of John Brown in 1859

    NASA Astrophysics Data System (ADS)

    Drobnock, G. J.; McBeath, A.; Gheorghe, A. D.

    2009-12-01

    An examination is made of metaphorical meteor imagery used in conjunction with the death of American anti-slavery activist John Brown, who was executed in December 1859. Such imagery continues to be used in this regard into the 21st century.

  9. Meteor Beliefs Project: some meteoric imagery in the works of William Shakespeare

    NASA Astrophysics Data System (ADS)

    McBeath, A.; Gheorghe, A. D.

    2003-08-01

    Passages from three of William Shakespeare's plays are presented, illustrating some of the beliefs in meteors in 16th-17th century England. They also reflect earlier beliefs and information which it is known Shakespeare drew on in constructing his works.

  10. A Global Model of Meteoric Sodium

    NASA Technical Reports Server (NTRS)

    Marsh, Daniel R.; Janches, Diego; Feng, Wuhu; Plane, John M. C.

    2013-01-01

    A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.

  11. A global model of meteoric sodium

    NASA Astrophysics Data System (ADS)

    Marsh, Daniel R.; Janches, Diego; Feng, Wuhu; Plane, John M. C.

    2013-10-01

    A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.

  12. Diversity, ecological distribution and biotechnological potential of Actinobacteria inhabiting seamounts and non-seamounts in the Tyrrhenian Sea.

    PubMed

    Ettoumi, Besma; Chouchane, Habib; Guesmi, Amel; Mahjoubi, Mouna; Brusetti, Lorenzo; Neifar, Mohamed; Borin, Sara; Daffonchio, Daniele; Cherif, Ameur

    2016-01-01

    In the present study, the ecological distribution of marine Actinobacteria isolated from seamount and non-seamount stations in the Tyrrhenian Sea was investigated. A collection of 110 isolates was analyzed by Automated Ribosomal Intergenic Spacer Analysis (ARISA) and 16S rRNA gene sequencing of representatives for each ARISA haplotype (n=49). Phylogenetic analysis of 16S rRNA sequences showed a wide diversity of marine isolates and clustered the strains into 11 different genera, Janibacter, Rhodococcus, Arthrobacter, Kocuria, Dietzia, Curtobacterium, Micrococcus, Citricoccus, Brevibacterium, Brachybacterium and Nocardioides. Interestingly, Janibacter limosus was the most encountered species particularly in seamounts stations, suggesting that it represents an endemic species of this particular ecosystem. The application of BOX-PCR fingerprinting on J. limosus sub-collection (n=22), allowed their separation into seven distinct BOX-genotypes suggesting a high intraspecific microdiversity among the collection. Furthermore, by screening the biotechnological potential of selected actinobacterial strains, J. limosus was shown to exhibit the most important biosurfactant activity. Our overall data indicates that Janibacter is a major and active component of seamounts in the Tyrrhenian Sea adapted to low nutrient ecological niche.

  13. Aging comets and their meteor showers

    NASA Astrophysics Data System (ADS)

    Ye, Quan-Zhi

    2016-10-01

    Comets are thought to be responsible for the terrestrial accretion of water and organic materials. The aging of comets is one of the most critical yet poorly understood problems in planetary astronomy. Here we attack this problem by examining different parts of the cometary aging spectrum of Jupiter-family comets (JFCs), a group of comets that dominates the cometary influx in the near-Earth space, using both telescopic and meteor observations.We examine two representative JFCs and the population of dormant comets. At the younger end of the aging spectrum, we examine a moderately active JFC, 15P/Finlay, and review the puzzle of the non-detection of the associated Finlayid meteor shower. We find that, although having been behaved like a dying comet in the past several 102 years, 15P/Finlay does possess ability for energetic outbursts without a clear reason. Towards the more aged end of the spectrum, we examine a weakly active JFC, 209P/LINEAR. By bridging telescopic observations at visible and infrared wavelength, meteor observations and dynamical investigations, we find that 209P/LINEAR is indeed likely an aged yet long-lived comet. At the other end of the spectrum, we examine the population of dormant near-Earth comets, by conducting a comprehensive meteor-based survey looking for dormant comets that have recently been active. We find the lower limit of the dormant comet fraction in the near-Earth object (NEO) population to be 2.0 ± 1.7%. This number is at the lower end of the numbers found using dynamical and telescopic techniques, which may imply that a significant fraction of comets in the true JFC population are weakly active and are not yet detected.These results have revealed interesting diversities in dying or dead comets, both in their behaviors as well as their natures. An immediate quest in the understanding of cometary aging would be to examine a large number of dying or dead comets and understand their general characteristics.

  14. Endemicity, Biogeography, Composition, and Community Structure On a Northeast Pacific Seamount

    PubMed Central

    McClain, Craig R.; Lundsten, Lonny; Ream, Micki; Barry, James; DeVogelaere, Andrew

    2009-01-01

    The deep ocean greater than 1 km covers the majority of the earth's surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a ‘seamount’, residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats. PMID:19127302

  15. Seafloor structure near the epicenter of the great 25 March 1998 Antarctic Plate earthquake

    NASA Astrophysics Data System (ADS)

    Nogi, Yoshifumi

    2013-01-01

    The great Antarctic Plate earthquake (M 8.1) that took place on 25 March 1998 was one of the largest oceanic intraplate strike-slip events ever recorded, but the cause of the earthquake is still unclear. Detailed marine geophysical surveys were conducted near the epicenter of the earthquake, and the results of swath bathymetry and the magnetic and gravity anomalies are presented. The data revealed the detailed structure of a seamount just south of the epicenter of the main shock. Two possible structures, which may represent the faults of the Antarctic Plate earthquake during the first subevent, were inferred from the geophysical data collected during the cruise by taking the uncertainties in the location of the epicenter and the distribution of the aftershocks into account, and the foot of the north-side escarpment of the seamount may indicate the main fault of the first strike-slip subevent of the Antarctic Plate earthquake. The north-side escarpment of the seamount was most likely formed before the Antarctic Plate earthquake, indicating that the earthquake occurred along preexisting structures. The magnetic anomaly and structural trends near the seamount are different from those in adjacent areas, and the area near the seamount is likely a block that was captured during ridge reorganization. Moreover, the area near the seamount may be a crustal fragment that was formed during initial rifting between Antarctica and Australia.

  16. Goals, technique and equipment of meteor study in Russia

    NASA Astrophysics Data System (ADS)

    Kartashova, A.; Bagrov, A. V.; Bolgova, G. T.; Kruchkov, S. V.; Leonov, V. A.; Mazurov, V. A.

    2013-09-01

    Institute of Astronomy RAS is one of the science institutes in the Russian Federation providing systematic optical meteor observations and supervises several meteor groups in our country. The main tasks of our investigations are dedicated to study meteoroid nature as well as meteoroid streams and meteoroid population in the Solar System. In the XXI century we in Russia carry out the reconstruction of our meteor astronomy due to possibilities of new meteor observation equipment (more powerful than were used before as visual and photographic methods) had made possible to select more interesting goals. First of our task is investigation of meteoroid streams crossing the Earth's orbit, and character of meteoroid distributions along of them. The multi stations meteor monitoring from located in the both hemispheres of the Earth can help in this study. According to the analysis of the evolution of meteor orbits, the compact and long lived meteoroid streams consist mainly from large particles. The observation equipment (cheap TV-cameras) with low limiting magnitude we use for gathering observational data. On the other hand, the observations of weak meteors are needed for new meteor shower indication (or confirmation of known meteor shower). The more effective way to do it is comparison of individual meteor orbits parameters (then calculation of radiants of meteor showers). The observations of space debris (as the meteors with low velocity - less 11.2 km/s) can be taking up within this task. The combination of high sensitive TV-cameras WATEC and super-fast lenses COMPUTAR are widely used for meteor TV-monitoring. The TVsystems for round-year meteor observations are fixed and are permanently oriented to the zenith area (the patrol camera - PatrolCa). The mobile TV-cameras (MobileCa) are used for double station observations (if it is possible) and located not far from main cameras PatrolCa (20-30 km). The mobile TVcameras observe 90% of main PatrolCa cameras FOV at altitudes

  17. Double camera configuration Assistant program for meteor stations

    NASA Astrophysics Data System (ADS)

    De Cicco, Marcelo

    2016-04-01

    Recently we build a program to assist double cameras coverage configuration. The DOCCA (double camera configuration assistant) software is in its first version, and is based on mathematic language, but yet helps the network to improve double detections meteors. It takes in account the distance stations, the high of an ideal meteor brightness, and an average ‘r’ factor for a typical shower.

  18. Investigation of meteor shower parent bodies using various metrics

    NASA Astrophysics Data System (ADS)

    Dumitru, B. A.; Birlan, M.; Nedelcu, A.; Popescu, M.

    2016-01-01

    The present knowledge of meteor showers identifies the small bodies of our Solar System as supply sources for meteor streams. Both comets and asteroids are considered as the origin of meteor showers. The new paradigm of "active asteroids" opens up a large field of investigation regarding the relationships between asteroids and meteors. Processes like ejection and disaggregation at impacts, rotational instabilities, electrostatic repulsion, radiation pressure, dehydration stress followed by thermal fractures, sublimation of ices are sources of matter loss from asteroids. Our objective is to find genetic relationships between asteroids and meteor showers using metrics based on orbital elements. For this objective we selected three metrics (Southworth and Hawkins, 1963; Asher et al. 1993, and Jopek, 1993, respectively), the recent MPC database and the more recent IAU meteor shower database. From our analysis, 41 of the meteor showers have probabilities of being produced (or to be fueled) by asteroids. Our sample of asteroids contains more than 1000 objects, all of them belonging to the Near-Earth Asteroid population. The systematic approach performed, based on the physical properties of our sample, reinforced the link between asteroids and their associated meteor shower.

  19. The 2011 Draconids: The First European Airborne Meteor Observation Campaign

    NASA Astrophysics Data System (ADS)

    Vaubaillon, Jeremie; Koten, Pavel; Margonis, Anastasios; Toth, Juraj; Rudawska, Regina; Gritsevich, Maria; Zender, Joe; McAuliffe, Jonathan; Pautet, Pierre-Dominique; Jenniskens, Peter; Koschny, Detlef; Colas, Francois; Bouley, Sylvain; Maquet, Lucie; Leroy, Arnaud; Lecacheux, Jean; Borovicka, Jiri; Watanabe, Junichi; Oberst, Jürgen

    2015-02-01

    On 8 October 2011, the Draconid meteor shower (IAU, DRA) was predicted to cause two brief outbursts of meteors, visible from locations in Europe. For the first time, a European airborne meteor observation campaign was organized, supported by ground-based observations. Two aircraft were deployed from Kiruna, Sweden, carrying six scientists, 19 cameras and eight crew members. The flight geometry was chosen such that it was possible to obtain double-station observations of many meteors. The instrument setup on the aircraft as well as on the ground is described in full detail. The main peak from 1900-dust ejecta happened at the predicted time and at the predicted rate. The second peak was observed from the earlier flight and from the ground, and was caused most likely by trails ejected in the nineteenth century. A total of 250 meteors were observed, for which light curve data were derived. The trajectory, velocity, deceleration and orbit of 35 double station meteors were measured. The magnitude distribution index was high, as a result of which there was no excess of meteors near the horizon. The light curve proved to be extremely flat on average, which was unexpected. Observations of spectra allowed us to derive the compositional information of the Draconids meteoroids and showed an early release of sodium, usually interpreted as resulting from fragile meteoroids. Lessons learned from this experience are derived for future airborne meteor shower observation campaigns.

  20. Comets and meteors in the beliefs of ancient mayas

    NASA Astrophysics Data System (ADS)

    Yershova, G. G.

    2001-12-01

    Data concerning the Mayan approach to comets and meteors have till now been available mostly from ethnographical and folklore sources which dealt, as a rule, with various beliefs and tokens. The studies of hieroglyphic texts of the Classic Period (AD 600-900) have proved that comets and meteors were undoubtedly known in this culture through astronomical observations and their periodicity.

  1. Abstracts for the International Conference on Asteroids, Comets, Meteors 1991

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Topics addressed include: chemical abundances; asteroidal belt evolution; sources of meteors and meteorites; cometary spectroscopy; gas diffusion; mathematical models; cometary nuclei; cratering records; imaging techniques; cometary composition; asteroid classification; radio telescopes and spectroscopy; magnetic fields; cosmogony; IUE observations; orbital distribution of asteroids, comets, and meteors; solar wind effects; computerized simulation; infrared remote sensing; optical properties; and orbital evolution.

  2. Meteor Showers of the Earth-crossing Asteroids

    NASA Astrophysics Data System (ADS)

    Pulat, Babadzhanov; Gulchekhra, Kokhirova

    2015-03-01

    The results of search for meteor showers associated with the asteroids crossing the Earthfs orbit and moving on comet-like orbits are given. It was shown that among 2872 asteroids discovered till 1.01.2005 and belonging to the Apollo and Amor groups, 130 asteroids have associated meteor showers and, therefore, are the extinct cometary nuclei.

  3. Correlating video meteors with GRAVES radio detections from the UK

    NASA Astrophysics Data System (ADS)

    Fleet, R.

    2015-01-01

    The area of meteor ablation layer illuminated by the GRAVES radar is low on the horizon from southern UK. A number of simultaneous video meteor and radio detections suggested that it was possible to record common events despite the unfavorable relative positions. This was investigated further to see what the constraints are and whether there is any prospect of obtaining useful data.

  4. First 3-D simulations of meteor plasma dynamics and turbulence

    NASA Astrophysics Data System (ADS)

    Oppenheim, Meers M.; Dimant, Yakov S.

    2015-02-01

    Millions of small but detectable meteors hit the Earth's atmosphere every second, creating trails of hot plasma that turbulently diffuse into the background atmosphere. For over 60 years, radars have detected meteor plasmas and used these signals to infer characteristics of the meteoroid population and upper atmosphere, but, despite the importance of meteor radar measurements, the complex processes by which these plasmas evolve have never been thoroughly explained or modeled. In this paper, we present the first fully 3-D simulations of meteor evolution, showing meteor plasmas developing instabilities, becoming turbulent, and inhomogeneously diffusing into the background ionosphere. These instabilities explain the characteristics and strength of many radar observations, in particular the high-resolution nonspecular echoes made by large radars. The simulations reveal how meteors create strong electric fields that dig out deep plasma channels along the Earth's magnetic fields. They also allow researchers to explore the impacts of the intense winds and wind shears, commonly found at these altitudes, on meteor plasma evolution. This study will allow the development of more sophisticated models of meteor radar signals, enabling the extraction of detailed information about the properties of meteoroid particles and the atmosphere.

  5. Numerical simulation of earthquake rupture sequences on the Manila thrust fault: Effects of seamount subduction

    NASA Astrophysics Data System (ADS)

    Yu, H.; Liu, Y.; Ning, J.; He, C.; Zhang, L.

    2015-12-01

    The Manila subduction zone is located at the convergent boundary between the Philippine Sea Plate and the Sunda/Eurasian Plate from offshore Taiwan to northern Luzon of Philippines, where only infrequent M7 earthquakes were observed in modern seismological instrumentation history. The lack of great events (M8+) indicates the subduction fault is either aseismically slipping or is accumulating strain energy toward rapid release in a great earthquake. Here we conduct numerical simulations of earthquake rupture sequences in the framework of rate-state-friction along the 15-19.5ºN segment of the 3D plate boundary with subducted seamounts. Rate-state frictional properties are constrained by laboratory friction experiments conducted on IODP Expedition 349, South China Sea (SCS), drilling samples from the basaltic basement rock under 100ºC - 600ºC, effective normal stress of 50 MPa and pore pressure of 100 MPa. During the modeled 2000-year period, the maximum magnitude of earthquakes is Mw7. Each sequence repeats every ~200 years and is consisted of three sub-events, event 1 (Mw7) that can overcome the barrier, where dip angle changes most rapidly along the strike, to rupture the entire fault. Events 2 (Mw 6.4) and 3 (Mw 5.7) are of smaller magnitudes and result in north-south segmented rupture pattern. We further quantify the potential of earthquake nucleation by the S-ratio (lower S ratio means the initial stress is closer to peak strength, hence more likely to nucleate an earthquake). The subducted seamount shows higher S-ratios than its surroundings mostly, implying an unlikely nucleate area. Our results are qualitatively similar to 2D subduction earthquake modeling by Herrendörfer et al. (2015, 2-3 events per supercycle and median long-term S is 0.5-1). Finally, we plan to use our coseismic rupture model results as inputs for a tsunami propagation model in SCS. Compared to the kinematic seafloor deformation input, our physics-based earthquake source model and its

  6. Meteoric Magnesium Ions in the Martian Atmosphere

    NASA Technical Reports Server (NTRS)

    Pesnell, William Dean; Grebowsky, Joseph

    1999-01-01

    From a thorough modeling of the altitude profile of meteoritic ionization in the Martian atmosphere we deduce that a persistent layer of magnesium ions should exist around an altitude of 70 km. Based on current estimates of the meteoroid mass flux density, a peak ion density of about 10(exp 4) ions/cm is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the correct density. Of these parameters, the peak density is most sensitive to the meteoroid mass flux density which directly determines the ablated line density into a source function for Mg. Unlike the terrestrial case, where the metallic ion production is dominated by charge-exchange of the deposited neutral Mg with the ambient ions, Mg+ in the Martian atmosphere is produced predominantly by photoionization. The low ultraviolet absorption of the Martian atmosphere makes Mars an excellent laboratory in which to study meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands.

  7. Meteor Trains - Terminology and Physical Interpretation

    NASA Astrophysics Data System (ADS)

    Borovička, Jirí

    2006-10-01

    This article presents a summary of various luminous phenomena that may follow after passage of a meteor. The terminology recommended by the International Astronomical Union in 1961 is used, which calls these phenomena trains. Nowadays, several types of trains can be clearly distinguished. The understanding of the underlying physical and chemical processes is, however, still not satisfactory and the nomenclature of different train phenomena has not yet been settled. In this paper I call them wake, green train, persistent train, and reflection train. Meteor wakes are formed by rarified non-equilibrium gas behind the meteoroid. The green train, produced by the radiation of the forbidden oxygen line at 557.7 nm, is created by reactions among atmospheric species. The persistent train is the most complex phenomenon with three phases of evolution. The afterglow phase is formed by cooling rarified gas. After that, atomic recombination phase follows. The third and most persistent continuum phase is probably fed by chemiluminescence. Finally, the reflection train occurs when sunlight is scattered by a dust cloud created by meteoroid disruption.

  8. The Taurid complex meteor showers and asteroids

    NASA Astrophysics Data System (ADS)

    Porubčan, V.; Kornoš, L.; Williams, I. P.

    2006-06-01

    The structure of the Taurid meteor complex based on photographic orbits available in the IAU Meteor database is studied. We have searched for potential sub-streams or filaments to be associated with the complex utilizing the Southworth-Hawkins D-criterion. Applying a strict limiting value for D=0.10, fifteen sub-streams or filaments, consisting of more than three members, could be separated out from the general complex. To confirm their mutual consistence as filaments, rather than fortuitous clumping at the present time, the orbital evolution over 5000 years of each member is studied. Utilizing the D-criterion we also searched for NEOs that might be associated with the streams and filaments of the complex and investigated the orbital evolution of potential members. Possible associations between 7 Taurid filaments and 9 NEOs were found. The most probable are for S Psc(b) -- 2003QC10, N Tau(a) -- 2004TG10, ο Ori -- 2003UL3 and N Tau(b) -- 2002XM35. Some of the potential parent objects could be either dormant comets or larger boulders moving within the complex. Three of the most populated filaments of the complex may have originated from 2P/Encke.

  9. THE RETURN OF THE ANDROMEDIDS METEOR SHOWER

    SciTech Connect

    Wiegert, Paul A.; Brown, Peter G.; Weryk, Robert J.; Wong, Daniel K.

    2013-03-15

    The Andromedid meteor shower underwent spectacular outbursts in 1872 and 1885, producing thousands of visual meteors per hour and described as ''stars fell like rain'' in Chinese records of the time. The shower originates from comet 3D/Biela whose disintegration in the mid-1800's is linked to the outbursts, but the shower has been weak or absent since the late 19th century. This shower returned in 2011 December with a zenithal hourly rate of approximately 50, the strongest return in over a hundred years. Some 122 probable Andromedid orbits were detected by the Canadian Meteor Orbit Radar while one possible brighter Andromedid member was detected by the Southern Ontario Meteor Network and several single station possible Andromedids by the Canadian Automated Meteor Observatory. The shower outburst occurred during 2011 December 3-5. The radiant at R.A. +18 Degree-Sign and decl. +56 Degree-Sign is typical of the ''classical'' Andromedids of the early 1800s, whose radiant was actually in Cassiopeia. Numerical simulations of the shower were necessary to identify it with the Andromedids, as the observed radiant differs markedly from the current radiant associated with that shower. The shower's orbital elements indicate that the material involved was released before 3D/Biela's breakup prior to 1846. The observed shower in 2011 had a slow geocentric speed (V{sub G} = 16 km s{sup -1}) and was comprised of small particles: the mean measured mass from the radar is {approx}5 Multiplication-Sign 10{sup -7} kg, corresponding to radii of 0.5 mm at a bulk density of 1000 kg m{sup -3}. Numerical simulations of the parent comet indicate that the meteoroids of the 2011 return of the Andromedids shower were primarily ejected during 3D/Biela's 1649 perihelion passage. The orbital characteristics, radiant, and timing as well as the absence of large particles in the streamlet are all broadly consistent with simulations. However, simulations of the 1649 perihelion passage necessitate going

  10. A processing method and results of meteor shower radar observations

    NASA Technical Reports Server (NTRS)

    Belkovich, O. I.; Suleimanov, N. I.; Tokhtasjev, V. S.

    1987-01-01

    Studies of meteor showers permit the solving of some principal problems of meteor astronomy: to obtain the structure of a stream in cross section and along its orbits; to retrace the evolution of particle orbits of the stream taking into account gravitational and nongravitational forces and to discover the orbital elements of its parent body; to find out the total mass of solid particles ejected from the parent body taking into account physical and chemical evolution of meteor bodies; and to use meteor streams as natural probes for investigation of the average characteristics of the meteor complex in the solar system. A simple and effective method of determining the flux density and mass exponent parameter was worked out. This method and its results are discussed.

  11. Diurnal variation of overdense meteor echo duration and ozone

    NASA Technical Reports Server (NTRS)

    Simek, Milos

    1992-01-01

    The diurnal variation of the median duration of overdense sporadic radar meteor echoes is examined. The meteors recorded in August, December, and January by the Ondrejov meteor radar during the period 1958-1990 were used for the analysis. A maximum median echo duration 1-3 hours after the time of local sunrise in the meteor region confirms the already known sunrise effect. Minimum echo duration occurring at the time of sunset seems to be the most important point of diurnal variation of the echo duration, when ozone is no longer dissociated by solar UV radiation. The effect of diurnal changes of the echo duration should be considered when the mass distribution of meteor showers is analyzed.

  12. First results on video meteors from Crete, Greece

    NASA Astrophysics Data System (ADS)

    Maravelias, G.

    2012-01-01

    This work presents the first systematic video meteor observations from a, forthcoming permanent, station in Crete, Greece, operating as the first official node within the International Meteor Organization's Video Network. It consists of a Watec 902 H2 Ultimate camera equipped with a Panasonic WV-LA1208 (focal length 12mm, f/0.8) lens running MetRec. The system operated for 42 nights during 2011 (August 19-December 30, 2011) recording 1905 meteors. It is significantly more performant than a previous system used by the author during the Perseids 2010 (DMK camera 21AF04.AS by The Imaging Source, CCTV lens of focal length 2.8 mm, UFO Capture v2.22), which operated for 17 nights (August 4-22, 2010) recording 32 meteors. Differences - according to the author's experience - between the two softwares (MetRec, UFO Capture) are discussed along with a small guide to video meteor hardware.

  13. Emplacement, growth, and gravitational deformation of serpentinite seamounts on the Mariana forearc

    NASA Astrophysics Data System (ADS)

    Oakley, A. J.; Taylor, B.; Fryer, P.; Moore, G. F.; Goodliffe, A. M.; Morgan, J. K.

    2007-08-01

    Serpentinite seamounts, representing some of the first material outputs of the recycling process that takes place in subduction zones, are found on the outer Mariana forearc. Multichannel seismic (MCS) and bathymetric data collected in 2002 image the large-scale structures of five seamounts, as well as the pre-seamount basement geometry and sediment stratigraphy. We present data from three edifices that provide insights into seamount growth and internal deformation processes and allow us to support the interpretation that serpentinite mud volcanoes are formed by the episodic eruption of mud flows from a central region. The presence of thrust faulting at the base of Turquoise and Big Blue Seamounts, along with the low surface slopes (5°-18°) of all the seamounts studied, lead us to infer that these edifices spread laterally and are subject to gravitational deformation as they grow. Numerical simulations using the discrete element method (DEM) were used to model their growth and the origins of features that we see in MCS sections, such as basal thrusts, inward-dipping reflections and mid-flank benches. The DEM simulations successfully reproduced many of the observed features. Simulations employing very low basal and internal friction coefficients (~0.1 and ~0.4, respectively) provide the best match to the overall morphology and structures of the serpentinite seamounts. However the simulations do not capture all of the processes involved in seamount growth, such as withdrawal of material from a central conduit leading to summit deflation; compaction, dewatering and degassing of mud flows; mass wasting in the form of sector collapse and growth upon a dipping substrate. A strong reflection beneath the summit of Big Blue, the largest serpentinite seamount on the Mariana forearc, represents the floor of a summit depression that has been partially in-filled by younger muds, supporting the idea that serpentinite seamounts grow by episodic mud volcanism. Boundaries of mud

  14. Circulation, stratification and seamounts in the Southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Pollard, Raymond; Read, Jane

    2017-02-01

    Circulation in the vicinity of six seamounts along the Southwest Indian Ridge was studied as part of a multidisciplinary survey in November 2009. Examination of altimetric data shows that several of the seamounts lie in the area of slow mean westward flow between the southern tip of Madagascar (25°S) and the Agulhas Return Current (ARC) flowing eastward between 37°S and 40°S. The mean westward drift of mesoscale features was 4.1±0.9 cm s-1. Integrated between Madagascar and 37°S, this westward drift can account for 50 Sv (1 Sv=106 m3 s-1), which, added to 25 Sv of southward flow past Madagascar, is sufficient to account for the total Agulhas Current transport of 70±21 Sv. The transport of the ARC was also measured, at two longitudes, down to 2000 m. Combined with earlier crossings of the ARC in 1986 and 1995, the full depth transport of the ARC is estimated at 71-85 Sv at longitudes 40-50°E, indicating that the Agulhas Current then ARC transport continues unreduced as far as 50°E before beginning to recirculate in the Southwest Indian Ocean subtropical gyre. The primary control on the circulation near each seamount was its position relative to any mesoscale eddy at the time of the survey. Melville lay on the flank of a cyclonic eddy that had broken off the ARC and was propagating west before remerging with the next meander of the ARC. Nearby Sapmer, on the other hand, was in the centre of an anticyclonic eddy, resulting in very weak stratification over the seamount at the time of the survey. Middle of What lies most often on the northern flank of the ARC, in strong currents, but was at the time of the survey near the edge of the same eddy as Sapmer. Coral, in the Subtropical Front south of the ARC, was in waters much colder, fresher, denser and more oxygenated than all the other seamounts. Walter was close to the path of eddies propagating southwest from east of Madagascar, while Atlantis, the furthest east and north seamount, experienced the weakest eddy

  15. The Updated IAU MDC Catalogue of Photographic Meteor Orbits

    NASA Technical Reports Server (NTRS)

    Porubcan, V.; Svoren, J.; Neslusan, L.; Schunova, E.

    2011-01-01

    The database of photographic meteor orbits of the IAU Meteor Data Center at the Astronomical Institute SAS has gradually been updated. To the 2003 version of 4581 photographic orbits compiled from 17 different stations and obtained in the period 1936-1996, additional new 211 orbits compiled from 7 sources have been added. Thus, the updated version of the catalogue contains 4792 photographic orbits (equinox J2000.0) available either in two separate orbital and geophysical data files or a file with the merged data. All the updated files with relevant documentation are available at the web of the IAU Meteor Data Center. Keywords astronomical databases photographic meteor orbits 1 Introduction Meteoroid orbits are a basic tool for investigation of distribution and spatial structure of the meteoroid population in the close surroundings of the Earth s orbit. However, information about them is usually widely scattered in literature and often in publications with limited circulation. Therefore, the IAU Comm. 22 during the 1976 IAU General Assembly proposed to establish a meteor data center for collection of meteor orbits recorded by photographic and radio techniques. The decision was confirmed by the next IAU GA in 1982 and the data center was established (Lindblad, 1987). The purpose of the data center was to acquire, format, check and disseminate information on precise meteoroid orbits obtained by multi-station techniques and the database gradually extended as documented in previous reports on the activity of the Meteor Data Center by Lindblad (1987, 1995, 1999 and 2001) or Lindblad and Steel (1993). Up to present, the database consists of 4581 photographic meteor orbits (Lindblad et al., 2005), 63.330 radar determined orbit: Harvard Meteor Project (1961-1965, 1968-1969), Adelaide (1960-1961, 1968-1969), Kharkov (1975), Obninsk (1967-1968), Mogadish (1969-1970) and 1425 video-recordings (Lindblad, 1999) to which additional 817 video meteors orbits published by Koten el

  16. Stepwise coupled mode scattering of ambient noise by a cylindrically symmetric seamount.

    PubMed

    Evans, Richard B

    2006-01-01

    The question of how underwater ambient noise, at low frequencies, interacts with seamounts is addressed. The vertical directivity of the ambient noise, with and without the seamount interaction, is of particular interest. The problem of ambient noise scattering by seamounts motivates the development of a numerical modeling procedure, based on stepwise coupled modes. The procedure is designed to analyze scattering from a cylindrically symmetric seamount. The stepwise coupled mode procedure is extended to more general boundary conditions and brought up to date in the process. An example, using the geometry of the Dickins seamount, suggests that the seamount removes energy from the steeply traveling ambient noise, for this case. The energy is not converted into angles near the horizontal; the energy is lost through bottom interaction and attenuation.

  17. Meteor Crater (Barringer Meteorite Crater), Arizona: Summary of Impact Conditions

    NASA Astrophysics Data System (ADS)

    Roddy, D. J.; Shoemaker, E. M.

    1995-09-01

    -field rock and meteorite ejecta parameters, 13) Inferred and estimated cloud-rise and fall-out conditions, 14) Late-stage meteorite falls after impact, 15) Estimated damage effect ranges, 16) Erosion of crater and ejecta blanket, 17) New topographic and digital maps of crater and ejecta blanket, 18) Other. (Suggestions are welcome) This compilation will contain expanded discussions of new data as well as revised interpretations of existing information. For example in Item 1, we suggest the impacting body most likely formed during a collision in the main asteroid belt that fragmented the iron-nickel core of an asteroid some 0.5 billion years ago. The fragments remained in space until about 50,000+/-3000 yrs ago, when they were captured by the Earth's gravitational field. In Item 3, the trajectory of the impacting body is interpreted by EMS as traveling north-northwest at a relatively low impact angle. The presence of both shocked meteorite fragments and melt spherules indicate the meteorite had a velocity in the range of about 13 to 20 km/s, probably in the lower part of this range [4]. In Item 4, the coherent meteorite diameter is estimated to have been 45 to 50 m with a mass of 300,000 to 400,000 tons, i.e., large enough to experience less than 1% in both mass ablation and velocity deceleration. During this time, minor flake-off of the meteorite's exterior produced a limited number of smaller fragments that followed the main mass to the impact site but at greatly reduced velocities. In Item 6, we estimate the kinetic energy of impact to be in the range of 20 to 40 Mt depending on the energy coupling functions used and corrections for angle of oblique impact. At impact, terrain conditions were about as we see them today, a gently rolling plain with outcrops of Moenkopi and a meter or so of soil cover. In Item 18, EMS estimates production of a Meteor Crater-size event should occur on the continents about every 50,000 years; interestingly, this is the age of Meteor Crater

  18. A study of meteor spectroscopy and physics from earth-orbit: A preliminary survey into ultraviolet meteor spectra

    NASA Technical Reports Server (NTRS)

    Meisel, D. D.

    1976-01-01

    Preliminary data required to extrapolate available meteor physics information (obtained in the photographic, visual and near ultraviolet spectral regions) into the middle and far ultraviolet are presented. Wavelength tables, telluric attenuation factors, meteor rates, and telluric airglow data are summarized in the context of near-earth observation vehicle parameters using moderate to low spectral resolution instrumentation. Considerable attenuation is given to the problem of meteor excitation temperatures since these are required to predict the strength of UV features. Relative line intensities are computed for an assumed chondritic composition. Features of greatest predicted intensities, the major problems in meteor physics, detectability of UV meteor events, complications of spacecraft motion, and UV instrumentation options are summarized.

  19. Dispersal and Retention of Benthic Invertebrate Larvae in Flows Near a Seamount

    DTIC Science & Technology

    1994-07-13

    of several seamount coral species was observed, and enhanced abundances of seabirds were documented near the seamount. On Volcano 7, a striking benthic...and a few (in particular, a barnacle and a serpulid worm) are found exclusively at the summit. Do these species have special life-history or behavioral...supported under this grant. During an expedition to Volcano 7 (a seamount off the coast of Mexico), a research team led by Karen Wishner investigated the

  20. On geoid heights and flexure of the lithosphere at seamounts

    NASA Astrophysics Data System (ADS)

    Watts, A. B.; Ribe, N. M.

    1984-12-01

    The sea surface height has now been mapped to an accuracy of better than ±1 m by using radar altimeters on board orbiting satellites. The major influence on the mean sea surface height is the marine geoid which is an equipotential surface. We have carried out preliminary studies of how oceanic volcanoes, which rise above the ocean floor as isolated seamounts and oceanic islands or linear ridges, contribute to the marine geoid. Simple one- and two-dimensional models have been constructed in which it is assumed that the oceanic lithosphere responds to volcanic loads as a thin elastic plate overlying a weak fluid substratum. Previous studies based on gravity and bathymetry data and uplift/subsidence patterns show that the effective flexural rigidity of oceanic lithosphere and the equivalent elastic thickness Te increase with the age of the lithosphere at the time of loading. The models predict that isolated seamounts emplaced on relatively young lithosphere on or near a mid-ocean ridge crest will be associated with relatively low amplitude geoid anomalies (about 0.4-0.5 m/km of height), while seamounts formed on relatively old lithosphere, on ridge flanks, will be associated with much higher amplitude anomalies (1.4-1.5 m/km). Studies of the Seasat altimetric geoid prepared by NASA's Jet Propulsion Laboratory support these model predictions; geoid amplitudes are relatively low over the Mid-Pacific Mountains and Line Islands, which formed on or near a mid-ocean ridge crest, and relatively high over the Magellan Seamounts and Wake Guyots, which formed off ridge. Direct modeling of the altimetric geoid over these features is complicated, however, by the wide spacing of the satellite tracks (which can exceed 100 km) and poor bathymetric control beneath individual satellite tracks. In regions where multibeam bathymetric surveys are available, models can be constructed that fit the altimetric geoid to better than ±1 m. Studies of geoid anomalies over the Emperor seamount

  1. Temperature tides determined with meteor radar

    NASA Astrophysics Data System (ADS)

    Hocking, W. K.; Hocking, A.

    2002-09-01

    A new analysis method for producing tidal temperature parameters using meteor radar measurements is presented, and is demonstrated with data from one polar and two mid-latitude sites. The technique further develops the temperature algorithm originally introduced by Hocking (1999). That earlier method was used to produce temperature measurements over time scales of days and months, but required an empirical model for the mean temperature gradient in the mesopause region. However, when tides are present, this temperature gradient is modulated by the presence of the tides, complicating extraction of diurnal variations. Nevertheless, if the vertical wavelengths of the tides are known from wind measurements, the effects of the gradient variations can be compensated for, permitting determination of temperature tidal amplitudes and phases by meteor techniques. The basic theory is described, and results from meteor radars at Resolute Bay (Canada), London (Canada) and Albuquerque (New Mexico, USA) are shown. Our results are compared with other lidar data, computer models, fundamental tidal theory and rocket data. Phase measurements at two mid-latitude sites (Albuquerque, New Mexico, and London, Canada) show times of maximum for the diurnal temperature tide to change modestly throughout most of the year, varying generally between 0 h and 6 h, with an excursion to 12 h in June at London. The semidiurnal tide shows a larger annual variation in time of maximum, being at 2 4 h in the winter months but increasing to 9 h during the late summer and early fall. We also find that, at least at mid-latitudes, the phase of the temperature tide matches closely the phase of the meridional tide, and theoretical justification for this statement is given. We also demonstrate that this is true using the Global Scale Wave Model (Hagan et al., 1999). Median values for the temperature amplitudes for each site are in the range 5 to 6 Kelvin. Results from a more northern site (Resolute Bay) show

  2. The MAGIC meteoric smoke particle sampler

    NASA Astrophysics Data System (ADS)

    Hedin, Jonas; Giovane, Frank; Waldemarsson, Tomas; Gumbel, Jörg; Blum, Jürgen; Stroud, Rhonda M.; Marlin, Layne; Moser, John; Siskind, David E.; Jansson, Kjell; Saunders, Russell W.; Summers, Michael E.; Reissaus, Philipp; Stegman, Jacek; Plane, John M. C.; Horányi, Mihály

    2014-10-01

    Between a few tons to several hundred tons of meteoric material enters the Earth's atmosphere each day, and most of this material is ablated and vaporized in the 70-120 km altitude region. The subsequent chemical conversion, re-condensation and coagulation of this evaporated material are thought to form nanometre sized meteoric smoke particles (MSPs). These smoke particles are then subject to further coagulation, sedimentation and global transport by the mesospheric circulation. MSPs have been proposed as a key player in the formation and evolution of ice particle layers around the mesopause region, i.e. noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). MSPs have also been implicated in mesospheric heterogeneous chemistry to influence the mesospheric odd oxygen/odd hydrogen (Ox/HOx) chemistry, to play an important role in the mesospheric charge balance, and to be a significant component of stratospheric aerosol and enhance the depletion of O3. Despite their apparent importance, little is known about the properties of MSPs and none of the hypotheses can be verified without direct evidence of the existence, altitude and size distribution, shape and elemental composition. The aim of the MAGIC project (Mesospheric Aerosol - Genesis, Interaction and Composition) was to develop an instrument and analysis techniques to sample for the first time MSPs in the mesosphere and return them to the ground for detailed analysis in the laboratory. MAGIC meteoric smoke particle samplers have been flown on several sounding rocket payloads between 2005 and 2011. Several of these flights concerned non-summer mesosphere conditions when pure MSP populations can be expected. Other flights concerned high latitude summer conditions when MSPs are expected to be contained in ice particles in the upper mesosphere. In this paper we present the MAGIC project and describe the MAGIC MSP sampler, the measurement procedure and laboratory analysis. We also present the attempts to

  3. Ocean eddies generated by seamounts in the north pacific.

    PubMed

    Royer, T C

    1978-03-10

    Small-scale (diameters of about 37 kilometers) fluctuations in dynamic topography north of Hawaii along 158 degrees W are well correlated with upstream seamounts. The fluctuations are subsurface but are manifested as baroclinic eddies at the sea surface. These eddies are confirmed by direct observations and supported by theoretical considerations. The eddies cause small-scale variability in the currents and hydrographic structures in this area, and they should be considered in any sampling programs of the region.

  4. Statistical self-similarity of hotspot seamount volumes modeled as self-similar criticality

    USGS Publications Warehouse

    Tebbens, S.F.; Burroughs, S.M.; Barton, C.C.; Naar, D.F.

    2001-01-01

    The processes responsible for hotspot seamount formation are complex, yet the cumulative frequency-volume distribution of hotspot seamounts in the Easter Island/Salas y Gomez Chain (ESC) is found to be well-described by an upper-truncated power law. We develop a model for hotspot seamount formation where uniform energy input produces events initiated on a self-similar distribution of critical cells. We call this model Self-Similar Criticality (SSC). By allowing the spatial distribution of magma migration to be self-similar, the SSC model recreates the observed ESC seamount volume distribution. The SSC model may have broad applicability to other natural systems.

  5. Subsidence and flexure along the Pratt-Welker seamount chain

    NASA Astrophysics Data System (ADS)

    Lambeck, K.; Penney, C. L.; Nakiboglu, S. M.; Coleman, R.

    1984-02-01

    A geophysical examination of the degree of isostatic compensation of guyots in the Pratt-Welker seamount chain in the Gulf of Alaska is presented in order to test the hypothesis of several previous studies that the origin of the Pratt-Welker chain cannot be attributed to a single cause. The test is carried out using GEOS 3 and Seasat altimeter data. The effective flexural rigidity of the lithosphere below all the seamounts in the chain is found to be less than about 10 to the 20th Nm, such that the isostatic state is local rather than regional. This may be the result of all seamounts having formed on an initially weak lithosphere. The subsidence of guyots in the chain is associated with numerous factors including thermal contraction of the seafloor, sediment loading, the flexure of the lithosphere prior to its subduction along the Aleutian Trench, and stress relaxation. The conclusions from the flexure and subsidence analyses are in agreement with the bulk of data from previous studies of the area.

  6. Meteoric Metal Layer in Mars' Atmosphere: Steady-state Flux and Meteor Showers

    NASA Astrophysics Data System (ADS)

    Crismani, Matteo; Schneider, Nicholas; Jain, Sonal; Plane, John; Diego Carrillo-Sanchez, Juan; Deighan, Justin; Stevens, Michael; Evans, Scott; Chaffin, Michael; Stewart, Ian; Jakosky, Bruce

    2016-04-01

    We report on a steady state metal ion layer at Mars produced by meteoric ablation in the upper atmosphere as observed by the Imaging Ultraviolet Spectrograph (IUVS) on MAVEN. The response of the Martian atmosphere to meteoroid influx constrains cometary activity, dust dynamics, ionospheric production at Mars and meteoric smoke may represent a site of nucleation for high altitude clouds. Using observations that span more than an Earth year, we find this layer is global and steady state, contrary to previous observations, but in accordance with predictions. IUVS observations cover a range of observation conditions, which allows us to determine the variability of the Mg+ layer seasonally and geographically. In December 2015, Mars encountered three predicted meteor showers, and analysis of these events will determine whether Mars' atmosphere responds to such events dramatically, as was the case with comet Siding Spring, or more similarly to Earth. Mg is also detected, but Mg/Mg+ less than predicted by factor >3, indicative of undetermined chemical processes in the Mars atmosphere.

  7. Comet Machholz and the Quadrantid meteor stream

    NASA Astrophysics Data System (ADS)

    Jones, J.; Jones, W.

    1993-04-01

    Until quite recently, the Quadrantid meteor stream was considered to be an 'orphan'. Because of the difficulty in accounting for the large difference in the longitudes of the ascending nodes, McIntosh (1990) suggested that Comet Machholz and the stream have a sibling rather than a parent-child relationship. Gonczi et al. (1992) proposed that gravitational perturbations by Jupiter may be amplified sufficiently by the 2:1 resonance of the stream with Jupiter to explain the difference in the longitudes of ascending nodes if the stream was born when the comet's perihelion distance was last at its minimum about 4000 yr ago. In this paper, we show by computer simulations that, if the comet was captured at its last close approach with Jupiter about 2200 yr ago, there has been sufficient time for the resulting stream to produce most of the features of the presently observed Quadrantid/Arietid/Southern Delta-Aquarid complex.

  8. Nitric oxide production by Tunguska meteor

    NASA Technical Reports Server (NTRS)

    Park, C.

    1978-01-01

    The nonequilibrium chemical processes of nitric oxide formation are computed for the wake of the Tunguska meteor of 1908. The wake characteristics are derived by carrying out an optically-thick radiation field analysis for ablation of the meteoroid. The wake flow field is approximated by a one-dimensional, well-stirred reactor model. Known characteristics of the Tunguska event are imposed as constraints, and three controlling parameters - chemical composition, density, and velocity - are varied over a range around the values derived by Korobeinikov et al. (1976) and Petrov and Stulov (1975). The calculation shows that at least 19 million tons of nitric oxide is produced between the altitudes of 10 and 50 km. The anomalous atmospheric phenomena following the event are attributed to the reactions involving nitric oxide thus produced and atmospheric ozone. It is speculated that the nitric oxide produced by the event fertilized the area near the fall, causing the observed rapid plant growth.

  9. On the ejection and dispersion velocities of meteor particles

    NASA Astrophysics Data System (ADS)

    Kresak, L.

    1992-07-01

    This paper is a reaction to the attempts to determine the ejection velocities of meteor particles from cometary nuclei using the statistics of photographic meteor orbits. It is argued that this is essentially impossible. The original dispersion velocities are masked completely by much larger measuring errors, and for all permanent meteor showers also by the accumulated effects of planetary perturbations. The perturbations, appearing after sufficient spread particles along the orbit, are on the average about 25-times more effective in the direction perpendicular to the orbital plane than in the direction of motion, and they are about 50-times more effective for typical comets of Jupiter family than for those of Halley type. The latter disproportion is responsible for the widely different distribution of the revolution periods of comets, annual meteor showers, and temporary meteor storms. In addition to direct spacecraft measurements, the only feasible sources of information on the ejection velocities are meteor storms, like the Draconids or Leonids, appearing only several times per century, and the cometary dust trail discovered by IRAS. Both of them indicate incomparably lower velocities than the meteor data - only a few meters per second - and a substantial role of the solar radiation pressure in the initial dispersion.

  10. The MU radar meteor head echo observation programme

    NASA Astrophysics Data System (ADS)

    Kero, Johan; Nakamura, Takuji; Nishimura, Koji; Meisel, David D.; Terasawa, Toshio; Masayoshi, Ueda; Fujiwara, Yasunori; Szasz, Csilla; Watanabe, Juniichi

    2012-07-01

    Earth's atmosphere is daily bombarded by billions of dust-sized particles. Those larger than a few tenths of a millimetre give rise to visible streaks of light on the night sky, meteors, or colloquially shooting stars. Meteor science contains many open questions, and the flux of extraterrestrial material into the Earth's atmosphere is one of them. High-power MST radars are powerful tools for providing new insights. This talk contains a review of meteor head echo observations with the 46.5 MHz Shigaraki Middle and Upper atmosphere (MU) radar in Japan (34.85N, 136.10E). We conducted a systematic set of monthly 24 h observations from 2009 June to 2010 December (>500 h) resulting in more than 100,000 high-quality meteor detections. Meteor showers are caused by the Earth intersecting streams of meteoroids on orbits still very similar to those of their parent bodies, usually comets. Meteor showers provide opportunities to compare head echo observations with other observation techniques and simulations. We present comparisons indicating that the head echo radar method provides precision and accuracy comparable to the photographic reduction of much brighter meteors with longer detectable trajectories.

  11. eMeteorNews: website and PDF journal

    NASA Astrophysics Data System (ADS)

    Roggemans, P.; Kacerek, R.; Koukal, J.; Miskotte, K.; Piffl, R.

    2016-01-01

    Amateur meteor workers have always been interested to exchange information and experience. In the past this was only possible via personal contacts by letter or by specialized journals. With internet a much faster medium became available and plenty of websites, mailing lists, Facebook groups, etc., have been created in order to communicate about meteors. Today there is a wealth of meteor data circulating on internet, but the information is very scattered and not directly available to everyone. The authors have been considering how to organize an easy access to the many different meteor related publications. The best solution for the current needs of amateur meteor observers proved to be a dedicated website combined with a PDF journal, both being free available without any subscription fee or registration requirement. The authors decided to start with this project and in March 2016 the website meteornews.org has been created. A first issue of eMeteorNews was prepared in April 2016. The year 2016 will be a test period for this project. The mission statement of this project is: "Minimizing overhead and editorial constraints to assure a swift exchange of information dedicated to all fields of active amateur meteor work."

  12. Why to start with eMeteorNews?

    NASA Astrophysics Data System (ADS)

    Roggemans, Paul

    2016-01-01

    Amateur meteor workers have always been interested to exchange information and experience. In the past this was only possible via personal contacts by letter or by specialized journals. With internet a much faster medium became available and plenty of websites, mailing lists, Facebook groups, etc., have been created in order to communicate about meteors. Today there is a wealth of meteor data circulating on internet, but the information is very scattered and not directly available to everyone. The authors have been considering how to organize an easy access to the many different meteor related publications. The best solution for the current needs of amateur meteor observers proved to be a dedicated website combined with a PDF journal, both being free available without any subscription fee or registration requirement. The authors decided to start with this project and in March 2016 the website meteornews.org has been created. A first issue of eMeteorNews has been prepared in May 2016. The year 2016 will be a test period for this project. The mission statement of this project is: “Minimizing overhead and editorial constraints to assure a swift exchange of information dedicated to all fields of active amateur meteor work.”

  13. Comet P/Machholtz and the Quadrantid meteor stream

    SciTech Connect

    Mcintosh, B.A. )

    1990-07-01

    Attention is drawn to the suggestive similarities between the calculated perturbation behavior of Comet P/Machholtz 1986 VIII, on the one hand, and on the other those of the Quadrantid, Delta Aquarid, and Arietid meteor streams. There appears to be adequate evidence for the formation by the Comets P/Machholtz and 1491-I, together with the three meteor streams, of a related complex controlled by Jupiter's gravitational perturbations; there is no comparably compelling information, however, bearing on the questions of parent-offspring or sibling relationships among these comets and meteor streams. 13 refs.

  14. New approaches to some methodological problems of meteor science

    NASA Astrophysics Data System (ADS)

    Meisel, David D.

    1987-08-01

    Several low cost approaches to continuous radio-scatter monitoring of the incoming meteor flux are described. Preliminary experiments were attempted using standard time frequency stations WWVH and CHU (on frequencies near 15 MHz) during nighttime hours. Around-the-clock monitoring using the international standard aeronautical beacon frequency of 75 MHz was also attempted. The techniques are simple and can be managed routinely by amateur astronomers with relatively little technical expertise. Time series analysis can now be performed using relatively inexpensive microcomputers. Several algorithmic approaches to the analysis of meteor rates are discussed. Methods of obtaining optimal filter predictions of future meteor flux are also discussed.

  15. Double station observation of faint meteors in Nikolaev

    NASA Astrophysics Data System (ADS)

    Kulichenko, Mykola; Shulga, Alexandr; Sybiryakova, Yevgeniya

    2016-07-01

    Meteor research using TV CCD unintensified techniques was started in 2011 in Nikolaev astronomical observatory (RI NAO). The method of meteor registration is based on combined observation method developed at RI NAO. The main accent of the research is made on precise astrometry and meteoroid orbits calculation. In 2013 first double station meteors with low baseline were observed. The accuracy of visible radiant estimation is 0.7" with baseline 5 km, and less 0.5" with baseline 11.8 km. The accuracy of velocity and height estimation is 0.5 km/s and 1-2 km.

  16. PRISMA, Italian network for meteors and atmospheric studies

    NASA Astrophysics Data System (ADS)

    Gardiol, D.; Cellino, A.; Di Martino, M.

    2016-01-01

    The aim of the PRISMA project is to develop the Italian participation in a network of European observing facilities whose primary targets are bright meteors (the so-called bolides and fireballs) and the recovery of meteorites. Several all-sky cameras have been recently installed in France (FRIPON project), and we propose to do the same in Italy, interconnecting the Italian network with the French one. Such a network is of great interest for the studies of interplanetary bodies and the dynamical and physical evolution of the population of small bodies of the Solar System and for the studies of collected meteorites. Those eventually recovered will be classified and investigated from the petrologic, genetic and evolutionary points of view, analyzed for their spectral characteristics and compared with known asteroids. The possibility to measure the radioactivity of samples shortly after the fall using gamma-ray spectrometers available in the Osservatorio Astrofisico di Torino laboratories, will allow us to reveal the presence of short-lived cosmogenic radioisotopes. PRISMA is also very suitable for the purposes of atmospheric studies. This includes the statistics of cloud coverage and lightning frequencies, as well as the comparison of the optical depth measured using satellites and PRISMA cameras.

  17. A decadal survey of the Daytime Arietid meteor shower using the Canadian Meteor Orbit Radar

    NASA Astrophysics Data System (ADS)

    Bruzzone, J. S.; Brown, P.; Weryk, R. J.; Campbell-Brown, M. D.

    2015-01-01

    We present results from a 12 year survey of the Daytime Arietid meteor shower using the Canadian Meteor Orbit Radar, a VHF backscattering orbital meteor radar, covering the interval 2002-2013. This survey recorded more than 2 × 104 Daytime Arietid orbits having representative masses of 8 × 10-8 kg and sizes of ≈0.4 mm. The core activity for the Arietids is found in the range 73.5° ≤ λ⊙ ≤ 84.5° and shows a broad 4-d maximum centred near λ⊙ = 80.5° of 0.04 meteoroids km-2 h-1 producing meteors of equivalent radio magnitude of +6.5 from a mean radiant at αg = 44.9° ± 1.1°, δg = 25.5° ± 1 .0°. During the plateau of shower peak activity, the mass index of the stream reaches a minimum with s = 1.6-1.7. Contamination from another nearby shower (likely the Daytime Zeta Perseids) and/or sub-streams showing different orbits compared to the core of the stream is evident in the interval 60.5° ≤ λ⊙ ≤ 71.5°. Similar contamination beyond λ⊙ = 84.5° may be due to the Helion sporadic source. We also characterized the deceleration profiles for Daytime Arietid meteor echoes using several independent speed techniques including Fresnel pre-t0, Fresnel amplitude oscillation and time-of-flight speeds which together with modelling produced a best estimate for the stream's out-of-atmosphere speed of v∞ = 40.5 ± 0.7 km s-1. The mean radar orbit from our study is noticeably smaller in semi-major axis and eccentricity than is found for larger Arietids measured with optical systems, a difference which if real indicates a particle-size sorting of the stream orbit. The broad activity maximum, long duration of activity and particle-size dependence of the orbital elements suggest the stream is too old to have been solely formed during the breakup of the parent comet of the Marsden sunskirters about a millennium ago as proposed by Sekanina & Chodas.

  18. Is there a seamount effect on microbial community structure and biomass? The case study of Seine and Sedlo seamounts (northeast Atlantic).

    PubMed

    Mendonça, Ana; Arístegui, Javier; Vilas, Juan Carlos; Montero, Maria Fernanda; Ojeda, Alicia; Espino, Minerva; Martins, Ana

    2012-01-01

    Seamounts are considered to be "hotspots" of marine life but, their role in oceans primary productivity is still under discussion. We have studied the microbial community structure and biomass of the epipelagic zone (0-150 m) at two northeast Atlantic seamounts (Seine and Sedlo) and compared those with the surrounding ocean. Results from two cruises to Sedlo and three to Seine are presented. Main results show large temporal and spatial microbial community variability on both seamounts. Both Seine and Sedlo heterotrophic community (abundance and biomass) dominate during winter and summer months, representing 75% (Sedlo, July) to 86% (Seine, November) of the total plankton biomass. In Seine, during springtime the contribution to total plankton biomass is similar (47% autotrophic and 53% heterotrophic). Both seamounts present an autotrophic community structure dominated by small cells (nano and picophytoplankton). It is also during spring that a relatively important contribution (26%) of large cells to total autotrophic biomass is found. In some cases, a "seamount effect" is observed on Seine and Sedlo microbial community structure and biomass. In Seine this is only observed during spring through enhancement of large autotrophic cells at the summit and seamount stations. In Sedlo, and despite the observed low biomasses, some clear peaks of picoplankton at the summit or at stations within the seamount area are also observed during summer. Our results suggest that the dominance of heterotrophs is presumably related to the trapping effect of organic matter by seamounts. Nevertheless, the complex circulation around both seamounts with the presence of different sources of mesoscale variability (e.g. presence of meddies, intrusion of African upwelling water) may have contributed to the different patterns of distribution, abundances and also changes observed in the microbial community.

  19. Seismic stratigraphy of Detroit Seamount, Hawaiian-Emperor seamount chain: Post-hot-spot shield-building volcanism and deposition of the Meiji drift

    NASA Astrophysics Data System (ADS)

    Kerr, Bryan C.; Scholl, David W.; Klemperer, Simon L.

    2005-07-01

    Detroit Seamount, one of the northernmost seamounts of the Hawaiian-Emperor seamount chain, was formed at ca. 76 Ma. New seismic data suggest renewed volcanism as late as 25 m.y. after initial seamount formation. We use high-resolution single-channel seismic (SCS) data acquired over the summit of Detroit Seamount in 2001 on Ocean Drilling Program (ODP) Leg 197, supplemented by older SCS data acquired as part of the GLORIA mapping program of the U.S. Geological Survey, to characterize the seismic stratigraphy of Detroit Seamount. Volcanic edifices occur on the summit of the seamount and are older than the oldest beds of the Meiji drift (early Oligocene: ca. 34 Ma). On the basis of ash layers in ODP drill holes, we suggest the edifices were active throughout much of the Eocene (ca. 52-34 Ma), with activity possibly extending into the early Oligocene (<34 Ma). Hence the age difference between the shield-building lavas and the postshield cones on Detroit is far greater than the shield/postshield age differences observed on the Hawaiian Islands, suggesting that renewed volcanic activity and tectonic collapse may be possible on any of the Hawaiian Islands. We confirm earlier assertions that the thick sediment cap, Oligocene and younger in age, was deposited by an ocean-bottom current with a southeastward flow direction, along the northeast facing flank of the Emperor Seamount chain. This sediment cap, the Meiji drift, was deposited by a lower-velocity current than many other sediment drifts. A low-angle normal fault, dipping ˜19°, suggests topographic collapse of Detroit seamount sometime during the Eocene or late Cretaceous.

  20. Petrogenesis of Near-Ridge Seamounts: AN Investigation of Mantle Source Heterogeneity and Melting Processes

    NASA Astrophysics Data System (ADS)

    Baxter, N. L.; Perfit, M. R.; Lundstrom, C.; Clague, D. A.

    2010-12-01

    Near-ridge (NR) seamounts offer an important opportunity to study lavas that have similar sources to ridge basalts but have been less affected by fractionation and homogenization that takes place at adjacent spreading ridge axes. By studying lavas erupted at these off-axis sites, we have the potential to better understand source heterogeneity and melting and transport processes that can be applied to the ridge system as a whole. One purpose of our study is to investigate the role of dunite conduits in the formation of near-ridge seamount chains. We believe that near-ridge seamounts could form due to focusing of melts in dunite channels located slightly off-axis and that such conduits may be important in the formation and transport of melt both on- and off-axis (Lundstrom et al., 2000). New trace element and isotopic analyses of glasses from Rogue, Hacksaw, and T461 seamounts near the Juan de Fuca Ridge (JdFR), the Lamont Seamounts adjacent to the East Pacific Rise (EPR) ~ 10°N, and the Vance Seamounts next to the JdFR ~45°N provide a better understanding of the petrogenesis of NR seamounts. Our data indicate that lavas from these seamounts have diverse incompatible trace element compositions that range from highly depleted to slightly enriched in comparison to associated ridge basalts. Vance A lavas (the oldest in the Vance chain) have the most enriched signatures and lavas from Rogue seamount on the JdFR plate have the most depleted signatures. Sr-Nd-Pb isotopic ratios indicate that NR seamount lava compositions vary within the chains as well as within individual seamounts, and that there is some mixing between heterogeneous, small-scale mantle sources. Using the program PRIMELT2.XLS (Herzberg and Asimow, 2008), we calculated mantle potential temperatures (Tp) for some of the most primitive basalts erupted at these seamounts. Our data indicate that NR seamount lavas have Tp values that are only slightly higher than that of average ambient mantle. Variations in

  1. Organic matter composition and macrofaunal diversity in sediments of the Condor Seamount (Azores, NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Bongiorni, Lucia; Ravara, Ascensão; Parretti, Paola; Santos, Ricardo S.; Rodrigues, Clara F.; Amaro, Teresa; Cunha, Marina R.

    2013-12-01

    In recent years increasing knowledge has been accumulated on seamounts ecology; however their sedimentary environments and associated biological communities remain largely understudied. In this study we investigated quantity and biochemical composition of organic matter and macrofaunal diversity in sediments of the Condor Seamount (NE Atlantic, Azores). In order to test the effect of the seamount on organic matter distribution, sediment samples were collected in 6 areas: the summit, the northern and southern flanks and bases, and in an external far field site. Macrofauna abundance and diversity were investigated on the summit, the southern flank and in the far field site. The organic matter distribution reflected the complex hydrodynamic conditions occurring on the Condor. Concentrations of organic matter compounds were generally lower on the whole seamount than in the far field site and on the seamount summit compared to flanks and bases. A clear difference was also evident between the northern and southern slopes of the Condor, suggesting a role of the seamount in conditioning sedimentation processes and distribution of food resources for benthic consumers. Macrofauna assemblages changed significantly among the three sampling sites. High abundance and dominance, accompanied by low biodiversity, characterized the macrofauna community on the Condor summit, while low dominance and high biodiversity were observed at the flank. Our results, although limited to five samples on the seamount and two off the seamount, do not necessarily support the paradigm that seamounts are more biodiverse than the surrounding seafloor. However, the abundance (and biomass), functional diversity and taxonomical distinctiveness of the macrofaunal assemblages from the Condor Seamount suggest that seamounts habitats may play a relevant role in adding to the regional biodiversity.

  2. Changes in nematode communities in different physiographic sites of the condor seamount (north-East atlantic ocean) and adjacent sediments.

    PubMed

    Zeppilli, Daniela; Bongiorni, Lucia; Serrão Santos, Ricardo; Vanreusel, Ann

    2014-01-01

    Several seamounts are known as 'oases' of high abundances and biomass and hotspots of biodiversity in contrast to the surrounding deep-sea environments. Recent studies have indicated that each single seamount can exhibit a high intricate habitat turnover. Information on alpha and beta diversity of single seamount is needed in order to fully understand seamounts contribution to regional and global biodiversity. However, while most of the seamount research has been focused on summits, studies considering the whole seamount structure are still rather poor. In the present study we analysed abundance, biomass and diversity of nematodes collected in distinct physiographic sites and surrounding sediments of the Condor Seamount (Azores, North-East Atlantic Ocean). Our study revealed higher nematode biomass in the seamount bases and values 10 times higher in the Condor sediments than in the far-field site. Although biodiversity indices did not showed significant differences comparing seamount sites and far-field sites, significant differences were observed in term of nematode composition. The Condor summit harboured a completely different nematode community when compared to the other seamount sites, with a high number of exclusive species and important differences in term of nematode trophic diversity. The oceanographic conditions observed around the Condor Seamount and the associated sediment mixing, together with the high quality of food resources available in seamount base could explain the observed patterns. Our results support the hypothesis that seamounts maintain high biodiversity through heightened beta diversity and showed that not only summits but also seamount bases can support rich benthic community in terms of standing stocks and diversity. Furthermore functional diversity of nematodes strongly depends on environmental conditions link to the local setting and seamount structure. This finding should be considered in future studies on seamounts, especially in

  3. Changes in Nematode Communities in Different Physiographic Sites of the Condor Seamount (North-East Atlantic Ocean) and Adjacent Sediments

    PubMed Central

    Zeppilli, Daniela; Bongiorni, Lucia; Serrão Santos, Ricardo; Vanreusel, Ann

    2014-01-01

    Several seamounts are known as ‘oases’ of high abundances and biomass and hotspots of biodiversity in contrast to the surrounding deep-sea environments. Recent studies have indicated that each single seamount can exhibit a high intricate habitat turnover. Information on alpha and beta diversity of single seamount is needed in order to fully understand seamounts contribution to regional and global biodiversity. However, while most of the seamount research has been focused on summits, studies considering the whole seamount structure are still rather poor. In the present study we analysed abundance, biomass and diversity of nematodes collected in distinct physiographic sites and surrounding sediments of the Condor Seamount (Azores, North-East Atlantic Ocean). Our study revealed higher nematode biomass in the seamount bases and values 10 times higher in the Condor sediments than in the far-field site. Although biodiversity indices did not showed significant differences comparing seamount sites and far-field sites, significant differences were observed in term of nematode composition. The Condor summit harboured a completely different nematode community when compared to the other seamount sites, with a high number of exclusive species and important differences in term of nematode trophic diversity. The oceanographic conditions observed around the Condor Seamount and the associated sediment mixing, together with the high quality of food resources available in seamount base could explain the observed patterns. Our results support the hypothesis that seamounts maintain high biodiversity through heightened beta diversity and showed that not only summits but also seamount bases can support rich benthic community in terms of standing stocks and diversity. Furthermore functional diversity of nematodes strongly depends on environmental conditions link to the local setting and seamount structure. This finding should be considered in future studies on seamounts, especially in

  4. One year of United Kingdom Meteor Observation Network

    NASA Astrophysics Data System (ADS)

    Kacerek, Richard; Campbell-Burns, Peter

    2014-01-01

    United Kingdom Meteor Observation Network (UKMON) began data gathering in April 2012 with its first station placed in Ash Vale, Surrey. This contribution shows our progress of building a network in the UK during one year.

  5. Meteor Outbursts and Storms from the Spacecraft Hazard Perspective

    NASA Technical Reports Server (NTRS)

    Cooke, William; Moser, Danielle; Suggs, Rob

    2004-01-01

    The recent Leonid meteor storms have propelled meteor shower forecasting from an idea into the realm of practical application, invoked several times per year by numerous spacecraft. This paper will describe shower activity predictions, which give zenith hourly rate (ZHR) as a function of time, and how these are translated into spacecraft risks. Common spacecraft meteor shower mitigation strategies will also be discussed, and the important issue as to when to implement such operations considered. It should be noted that, while the recent meteor storms did not result in the loss of a vehicle, there were a few spacecraft anomalies attributed to Leonid strikes, and the nature of these will be commented upon. Finally, we assess the current state of the art in shower forecasting, and take a look "down the road" at some possible outbursts in the near future.

  6. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    NASA Astrophysics Data System (ADS)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.; Steele, A.; Treiman, A.

    2016-09-01

    Methane plumes in the martian atmosphere were previously reported, but their source remains a mystery. We hypothesize a meteor shower source, as we find a correlation between Mars/cometary orbit encounters and detections of plumes.

  7. Meteoric aspects of the Earth-grazing asteroid 2004 FH

    NASA Astrophysics Data System (ADS)

    Langbroek, M.

    2004-07-01

    A search for meteors potentially associated with the recent spectacular earthgrazing asteroid 2004 FH in the IAU photographic meteor database yields three meteors from the Harvard project, which is probably not enough to support the notion that 2004 FH is one of the larger meteoroids in a stream. The theoretical radiant is located at alpha = 226 g, delta = -4 g (for March 19), and meteors would have v_infty of about 13.2 km/s, which is very slow. Asteroid 2004 FH would only be dangerous if it is an M-class asteroid. A stony asteroid of this size and speed would disintegrate almost completely in the atmosphere without doing much harm. An M-class (iron) asteroid, however, would shower down fragments weighing many tons, creating a crater field with craters up to 100+ meters wide, and serious blast damage within a few kilometers.

  8. NASA Meteor Cam Video of June 2, 2016 Arizona Fireball

    NASA Video Gallery

    Video obtained from the NASA meteor camera situated at the MMT Observatory on the site of the Fred Lawrence Whipple Observatory, located on Mount Hopkins, Arizona, in the Santa Rita Mountains. Cred...

  9. Improving Photometric Calibration of Meteor Video Camera Systems

    NASA Technical Reports Server (NTRS)

    Ehlert, Steven; Kingery, Aaron; Cooke, William

    2016-01-01

    Current optical observations of meteors are commonly limited by systematic uncertainties in photometric calibration at the level of approximately 0.5 mag or higher. Future improvements to meteor ablation models, luminous efficiency models, or emission spectra will hinge on new camera systems and techniques that significantly reduce calibration uncertainties and can reliably perform absolute photometric measurements of meteors. In this talk we discuss the algorithms and tests that NASA's Meteoroid Environment Office (MEO) has developed to better calibrate photometric measurements for the existing All-Sky and Wide-Field video camera networks as well as for a newly deployed four-camera system for measuring meteor colors in Johnson-Cousins BV RI filters. In particular we will emphasize how the MEO has been able to address two long-standing concerns with the traditional procedure, discussed in more detail below.

  10. Density variations of meteor flux along the Earth's orbit

    NASA Technical Reports Server (NTRS)

    Svetashkova, N. T.

    1987-01-01

    No model of distribution of meteor substance is known to explain the observed diurnal and annual variations of meteor rates, if that distribution is assumed to be constant during the year. Differences between the results of observations and the prediction of diurnal variation rates leads to the conclusion that the density of the orbits of meteor bodies changes with the motion of the Earth along its orbit. The distributions of the flux density over the celestial sphere are obtained by the method described previously by Svetashkova, 1984. The results indicate that the known seasonal and latitudinal variations of atmospheric conditions does not appear to significantly affect the value of the mean flux density of meteor bodies and the matter influx onto the Earth.

  11. On the accuracy of orbits from video meteor observations

    NASA Astrophysics Data System (ADS)

    Skokić, I.; Šegon, D.; Kurtović, G.

    2016-01-01

    The velocity limits of the meteor shower's geocentric velocity distribution from the CAMS meteoroid database were determined and used to calculate perturbed orbits. These were compared with the mean stream orbit using the DSH dissimilarity criterion. It was found that for the slow meteor showers (Alpha Capricornids and Geminids), the resulting orbits are within the generally accepted cutoff values for stream associations, while for the faster showers (Perseids, Orionids and Quadrantids) the resulting orbits differ significantly from their mean stream orbit.

  12. The investigation of multiplet structures in meteor spectra

    NASA Astrophysics Data System (ADS)

    Mozgova, Alona; Churyumov, Klim

    2016-07-01

    The structures of the iron multiplets and some other elements observed in spectra of meteor comas were considered. The catalog of iron multiplets lines was made. For each term there are indicated energy levels and wavelengths of spectral lines. For clearly explaining the transitions that accompany the radiation in given multiplets the complete Grotrian diagrams were constructed. Spectral analysis has an important role in understanding the physical processes which occur in meteor comas. Each meteor spectrum contains a large number of spectral lines belonging to atoms of different chemical elements and has a multiplet structures. The multiplets are usually spaced pairs or triples of lines but the multiplet may consist of one or more lines than three. The studying of multiplet structures in meteor spectra makes it possible to investigate the properties and a behavior of atoms of the meteor body matter. It can be used for creating models of physical and chemical processes which occur during the meteor flight in the Earth's atmosphere. For some tasks of meteor physics it needs to know not only the wavelength of a line and its belonging to some multiplet, but also both the excitation potentials of the upper and lower levels. This is useful, for example, for the study of the atoms distribution over the levels and how it differs from the Boltzmann distribution, as well as for the construction of curves growth and for determining the temperature excitation in the meteor coma, etc. For this purpose, the Walt Grotrian diagrams or chart of terms are built. They show the allowed transitions between the energy levels of the atoms. These diagrams can be used for one or more electrons (multielectrons) in the atom. The specific selection rules are taken into account in their construction. These rules are related to the change in angular momentum of the electron.

  13. Origin of meteor swarms of the Arietid and Geminid types

    SciTech Connect

    Lebedinets, V.N.

    1985-10-01

    The author proposes a physical mechanism for the formation of meteor swarms on orbits of small size and very small perihelion distance, similar to the orbits of Arietid and Geminid meteor swarms, which are rarely encountered among the larger bodies of the solar system, and he justifies the mechanism mathematically. He shows that comets can transfer to such orbits from orbits of large size during evaporation of their ice nuclei under the action of reactive drag.

  14. Meteor Beliefs Project: Spears of GodSpears of God

    NASA Astrophysics Data System (ADS)

    Hendrix, Howard V.; McBeath, Alastair; Gheorghe, Andrei Dorian

    2012-04-01

    A selection of genuine or supposedly sky-fallen objects from real-world sources, a mixture of weapons, tools and "magical" objects of heavenly provenance, are drawn from their re-use in the near-future science-fiction novel Spears of God by author Howard V Hendrix, with additional discussion. The book includes other meteoric and meteoritic items too, some of which have been the subject of previous Meteor Beliefs Project examinations.

  15. Geochemistry and petrogenesis of volcanic rocks from Daimao Seamount (South China Sea) and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Yan, Quanshu; Castillo, Paterno; Shi, Xuefa; Wang, Liaoliang; Liao, Lin; Ren, Jiangbo

    2015-03-01

    The South China Sea (SCS) experienced three episodes of seafloor spreading and left three fossil spreading centers presently located at 18°N, 17°N and 15.5°N. Spreading ceased at these three locations during magnetic anomaly 10, 8, and 5c, respectively. Daimao Seamount (16.6 Ma) was formed 10 my after the cessation of the 17°N spreading center. Volcaniclastic rocks and shallow-water carbonate facies near the summit of Daimao Seamount provide key information on the seamount's geologic history. New major and trace element and Sr-Nd-Pb isotopic compositions of basaltic breccia clasts in the volcaniclastics suggest that Daimao and other SCS seamounts have typical ocean island basalt-like composition and possess a 'Dupal' isotopic signature. Our new analyses, combined with available data, indicate that the basaltic foundation of Daimao Seamount was formed through subaqueous explosive volcanic eruptions at 16.6 Ma. The seamount subsided rapidly (> 0.12 mm/y) at first, allowing the deposition of shallow-water, coral-bearing carbonates around its summit and, then, at a slower rate (< 0.12 mm/y). We propose that the parental magmas of SCS seamount lavas originated from the Hainan mantle plume. In contrast, lavas from contemporaneous seamounts in other marginal basins in the western Pacific are subduction-related.

  16. An introduction to the physical oceanography of six seamounts in the southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Read, Jane; Pollard, Raymond

    2017-02-01

    Exploratory surveys of six seamounts in the Southwest Indian Ocean provide a description of physical processes induced by seamounts along the Southwest Indian Ridge. Mean currents (15-25 cm s-1) in the vicinity of each seamount were dominated by mesoscale eddies. The dominant seamount-driven process was the generation of internal tides by the barotropic tide interacting with the seamount crests. This led to enhanced shear in the vicinity of the crests resulting in mixing where stratification was weak, for example in the core of an anticyclonic mesoscale eddy or where there had been a winter mixed layer. Tidally driven up- and downwelling was observed at the seabed with associated variability in bottom temperature of up to 3 °C over a tidal cycle. Vertical displacement of isopycnals by internal tidal waves reached 200 m peak to trough. Fluorescence in the surface (eutrophic) layer could thus extend down to the seamount crest on each tidal cycle. Apparently spatial variations in short conductivity/temperature/depth sections across each seamount were probably aliased temporal variations from the strong tidal signal. Evidence for Taylor caps or other potential trapped circulations at the seamount crest was weak, most likely because currents associated with mesoscale eddies were too strong to allow their formation.

  17. Megafauna associated with bathyal seamounts in the central North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Wilson, Raymond R.; Smith, Kenneth L.; Rosenblatt, Richard H.

    1985-10-01

    Sixteen fish species and 31 invertebrate species were identified on Horizon Guyot and five other bathyal seamounts in the central North Pacific Ocean from trawl and baited-trap collections augmented with video camera recordings. The seamount fauna shows zoogeographic affinities with fauna of the Indo-West Pacific as does the marine shore fauna of central Pacific Islands.

  18. Fish Biodiversity of the Vitória-Trindade Seamount Chain, Southwestern Atlantic: An Updated Database

    PubMed Central

    Pinheiro, Hudson T.; Mazzei, Eric; Moura, Rodrigo L.; Amado-Filho, Gilberto M.; Carvalho-Filho, Alfredo; Braga, Adriana C.; Costa, Paulo A. S.; Ferreira, Beatrice P.; Ferreira, Carlos Eduardo L.; Floeter, Sergio R.; Francini-Filho, Ronaldo B.; Gasparini, João Luiz; Macieira, Raphael M.; Martins, Agnaldo S.; Olavo, George; Pimentel, Caio R.; Rocha, Luiz A.; Sazima, Ivan; Simon, Thiony; Teixeira, João Batista; Xavier, Lucas B.; Joyeux, Jean-Christophe

    2015-01-01

    Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management. PMID:25738798

  19. 50 CFR Table 22 to Part 679 - Alaska Seamount Habitat Protection Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Alaska Seamount Habitat Protection Areas 22 Table 22 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... ZONE OFF ALASKA Pt. 679, Table 22 Table 22 to Part 679— Alaska Seamount Habitat Protection Areas...

  20. 50 CFR Table 22 to Part 679 - Alaska Seamount Habitat Protection Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Alaska Seamount Habitat Protection Areas 22 Table 22 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... ZONE OFF ALASKA Pt. 679, Table 22 Table 22 to Part 679— Alaska Seamount Habitat Protection Areas...

  1. 50 CFR Table 22 to Part 679 - Alaska Seamount Habitat Protection Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Alaska Seamount Habitat Protection Areas 22 Table 22 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... ZONE OFF ALASKA Pt. 679, Table 22 Table 22 to Part 679— Alaska Seamount Habitat Protection Areas...

  2. 50 CFR Table 22 to Part 679 - Alaska Seamount Habitat Protection Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Alaska Seamount Habitat Protection Areas 22 Table 22 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... ZONE OFF ALASKA Pt. 679, Table 22 Table 22 to Part 679— Alaska Seamount Habitat Protection Areas...

  3. 50 CFR Table 22 to Part 679 - Alaska Seamount Habitat Protection Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Alaska Seamount Habitat Protection Areas 22 Table 22 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... ZONE OFF ALASKA Pt. 679, Table 22 Table 22 to Part 679— Alaska Seamount Habitat Protection Areas...

  4. 15 CFR Appendix F to Subpart M of... - Davidson Seamount Management Zone

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 3 2013-01-01 2013-01-01 false Davidson Seamount Management Zone F Appendix F to Subpart M of Part 922 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... Sanctuary Pt. 922, Subpt. M, App. F Appendix F to Subpart M of Part 922—Davidson Seamount Management...

  5. 15 CFR Appendix F to Subpart M of... - Davidson Seamount Management Zone

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 3 2012-01-01 2012-01-01 false Davidson Seamount Management Zone F Appendix F to Subpart M of Part 922 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... Sanctuary Pt. 922, Subpt. M, App. F Appendix F to Subpart M of Part 922—Davidson Seamount Management...

  6. 50 CFR 665.200 - Hawaii bottomfish and seamount groundfish fisheries. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Hawaii bottomfish and seamount groundfish fisheries. 665.200 Section 665.200 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.200 Hawaii bottomfish and seamount groundfish fisheries....

  7. 50 CFR 665.200 - Hawaii bottomfish and seamount groundfish fisheries. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Hawaii bottomfish and seamount groundfish fisheries. 665.200 Section 665.200 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.200 Hawaii bottomfish and seamount groundfish fisheries....

  8. 50 CFR 665.200 - Hawaii bottomfish and seamount groundfish fisheries. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Hawaii bottomfish and seamount groundfish fisheries. 665.200 Section 665.200 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.200 Hawaii bottomfish and seamount groundfish fisheries....

  9. 15 CFR Appendix F to Subpart M of... - Davidson Seamount Management Zone

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 3 2014-01-01 2014-01-01 false Davidson Seamount Management Zone F Appendix F to Subpart M of Part 922 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... Sanctuary Pt. 922, Subpt. M, App. F Appendix F to Subpart M of Part 922—Davidson Seamount Management...

  10. Fish biodiversity of the Vitória-Trindade Seamount Chain, southwestern Atlantic: an updated database.

    PubMed

    Pinheiro, Hudson T; Mazzei, Eric; Moura, Rodrigo L; Amado-Filho, Gilberto M; Carvalho-Filho, Alfredo; Braga, Adriana C; Costa, Paulo A S; Ferreira, Beatrice P; Ferreira, Carlos Eduardo L; Floeter, Sergio R; Francini-Filho, Ronaldo B; Gasparini, João Luiz; Macieira, Raphael M; Martins, Agnaldo S; Olavo, George; Pimentel, Caio R; Rocha, Luiz A; Sazima, Ivan; Simon, Thiony; Teixeira, João Batista; Xavier, Lucas B; Joyeux, Jean-Christophe

    2015-01-01

    Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management.

  11. 50 CFR 665.200 - Hawaii bottomfish and seamount groundfish fisheries. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Hawaii bottomfish and seamount groundfish fisheries. 665.200 Section 665.200 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.200 Hawaii bottomfish and seamount groundfish fisheries....

  12. 50 CFR 665.200 - Hawaii bottomfish and seamount groundfish fisheries. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Hawaii bottomfish and seamount groundfish fisheries. 665.200 Section 665.200 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.200 Hawaii bottomfish and seamount groundfish fisheries....

  13. Geophysical investigation of seamounts near the Ogasawara Fracture Zone, western Pacific

    NASA Astrophysics Data System (ADS)

    Lee, T.-G.; Lee, K.; Hein, J. R.; Moon, J.-W.

    2009-03-01

    This paper provides an analysis of multi-channel seismic data obtained during 2000-2001 on seamounts near the Ogasawara Fracture Zone (OFZ) northwest of the Marshall Islands in the western Pacific. The OFZ is unique in that it is a wide rift zone that includes many seamounts. Seven units are delineated on the basis of acoustic characteristics and depth: three units (I, II, and III) on the summit of seamounts and four units (IV, V, VI, and VII) in basins. Acoustic characteristics of layers on the summit of guyots and dredged samples indicate that the seamounts had been built above sea level by volcanism. This was followed by reef growth along the summit margin, which enabled deposition of shallow-water carbonates on the summit, and finally by subsidence of the edifices. The subsidence depth of the seamounts, estimated from the lower boundary of unit II, ranges between 1,550 and 2,040 m. The thick unit I of the southern seamounts is correlated with proximity to the equatorial high productivity zone, whereas local currents may have strongly affected the distribution of unit I on northern seamounts. A seismic profile in the basin around the Ita Mai Tai and OSM4 seamounts shows an unconformity between units IV and V, which is widespread from the East Mariana Basin to the Pigafetta Basin.

  14. 15 CFR Appendix F to Subpart M of... - Davidson Seamount Management Zone

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Davidson Seamount Management Zone F Appendix F to Subpart M of Part 922 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... Sanctuary Pt. 922, Subpt. M, App. F Appendix F to Subpart M of Part 922—Davidson Seamount Management...

  15. 15 CFR Appendix F to Subpart M of... - Davidson Seamount Management Zone

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 3 2011-01-01 2011-01-01 false Davidson Seamount Management Zone F Appendix F to Subpart M of Part 922 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... Sanctuary Pt. 922, Subpt. M, App. F Appendix F to Subpart M of Part 922—Davidson Seamount Management...

  16. Discovery of the 2011 eruption at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Chadwick, B.; Nooner, S. L.; Butterfield, D. A.; Lilley, M. D.; Clague, D. A.; Caress, D. W.; Dziak, R. P.; Haxel, J. H.

    2011-12-01

    A new lava flow was discovered on the seafloor at Axial Seamount during an expedition in late July on R/V Atlantis with ROV Jason to conduct time-series monitoring and sampling. Major changes in depth, lava morphology, and the burial of pre-existing markers, monuments, and instruments made it clear that the new lava had not been there during the previous visit in August 2010. Pre-existing high-resolution bathymetry in the area aided in recognizing that the seafloor had changed significantly. The 2011 lava appears to have been erupted along the upper south rift, in a similar location to the 1998 eruption. The 2011 lava appears to be constrained by pre-existing topography to the east, but flowed at least 2 km downslope to the west, where it fills pre-existing channels and basins, and came with 170 m of the ASHES vent field near the SW caldera wall. The morphology of the 2011 lava is pillowed near the thin margins of the flows, and lobate elsewhere. The thin margins are the only places where the 2011 lava appears black, shiny, and new. Elsewhere where the lava is thicker it is covered by an orange/tan "eruption mat" (also observed after the 1998 eruption) that appears to be hydrothermal in origin, and is probably associated with cooling of the flow. In such places the 2011 lava looks deceptively "old". No collapse features were observed in the 2011 lavas, in marked contrast to the 1998 lava flow. This suggests that the 2011 eruption was longer-lived and larger in volume, consistent with the longer flow lengths. A fuller view of the extent of the 2011 lava flows will be provided by a coordinated re-survey collected with the MBARI mapping AUV on the heels of our Atlantis cruise. Hydrothermal venting on the 2011 lava flow was limited to isolated snow-blower vents and pre-existing vent sites, but we likely did not find all the sources of new venting in our limited dive time, based on the extremely poor visibility near the seafloor. CTD casts showed near bottom plumes up

  17. ``Hiss, clicks and pops'' - The enigmatic sounds of meteors

    NASA Astrophysics Data System (ADS)

    Finnegan, J. A.

    2015-04-01

    The improbability of sounds heard simultaneously with meteors allows the phenomenon to remain on the margins of scientific interest and research. This is unjustified, since these audibly perceived electric field effects indicate complex, inconsistent and still unresolved electric-magnetic coupling and charge dynamics; interacting between the meteor; the ionosphere and mesosphere; stratosphere; troposphere and the surface of the earth. This paper reviews meteor acoustic effects, presents illustrating reports and hypotheses and includes a summary of similar and additional phenomena observed during the 2013 February 15 asteroid fragment disintegration above the Russian district of Chelyabinsk. An augmenting theory involving near ground, non uniform electric field production of Ozone, as a stimulated geo-physical phenomenon to explain some hissing `meteor sounds' is suggested in section 2.2. Unlike previous theories, electric-magnetic field fluctuation rates are not required to occur in the audio frequency range for this process to acoustically emit hissing and intermittent impulsive sounds; removing the requirements of direct conversion, passive human transduction or excited, localised acoustic `emitters'. Links to the Armagh Observatory All-sky meteor cameras, electrophonic meteor research and full construction plans for an extremely low frequency (ELF) receiver are also included.

  18. The 2014 KCG Meteor Outburst: Clues to a Parent Body

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea V.; Brown, Peter G.; Spurny, Pavel; Cooke, William J.

    2015-01-01

    The Kappa Cygnid (KCG) meteor shower exhibited unusually high activity in 2014, producing ten times the typical number of meteors. The shower was detected in both radar and optical systems and meteoroids associated with the outburst spanned at least five decades in mass. In total, the Canadian Meteor Orbit Radar, European Network, and NASA All Sky and Southern Ontario Meteor Network produced thousands of KCG meteor trajectories. Using these data, we have undertaken a new and improved characterization of the dynamics of this little-studied, variable meteor shower. The Cygnids have a di use radiant and a significant spread in orbital characteristics, with multiple resonances appearing to play a role in the shower dynamics. We conducted a new search for parent bodies and found that several known asteroids are orbitally similar to the KCGs. N-body simulations show that the two best parent body candidates readily transfer meteoroids to the Earth in recent centuries, but neither produces an exact match to the KCG radiant, velocity, and solar longitude. We nevertheless identify asteroid 2001 MG1 as a promising parent body candidate.

  19. Optical observations of meteors in RI Nikolaev Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Shulga, Alexander; Sybiryakova, Yevgeniya; Kulichenko, Nikolay; Vovk, Vasyl

    2015-08-01

    Video observations of meteors at the RI NAO are conducted using meteor patrol, which includes 6 optical telescopes (4 lenses: f = 85 mm, f/1.8; 2 lenses: f = 100 mm, f/2.0) equipped with a TV CCD cameras WAT-902H2 (768×576, 8.6×8.3µ). The field of view of 4 telescopes is 3.2°×4.2° and 2.7°×3.6° for 2 telescopes. System doesn't have any intensifier. Each video system is contained in a hermetic capsule to prevent it from rain and other aggressive meteorological conditions. Cameras work in the interlace mode with rate 50 half-frames per second.During 2011-2014 4135 single station meteors were observed. The mean duration of observed meteor trajectories are in 0.05-0.6 s. Double station observation campaigns has been started in September 2013 and it is still working with baseline 11.8 km. During September 2013 - September 2014 total number of observed meteor trajectories was 1757. Number of double station meteors - 328. The mean accuracy of visible radiant determination is less than 0.5 arc sec, more than 80% of radiates have standard deviation less than 0.2 arc sec.

  20. Geochemical Diversity of Near-Ridge Seamounts: Insights into Oceanic Magmatic Processes and Sources

    NASA Astrophysics Data System (ADS)

    Baxter, N. L.; Perfit, M. R.; Wendt, R. E.; Lundstrom, C.; Clague, D. A.

    2009-12-01

    Geochemical studies of lavas erupted at seamounts that form in close proximity to active mid-ocean ridges provide an opportunity to better understand the composition of shallow mantle underneath spreading ridges and how it melts in order to form new oceanic crust. This is because while on-axis samples mostly reflect homogenization of melts within the axial magma lens, seamount lavas bypass this process providing a window into the diversity of melts produced in the melting column. We have analyzed lavas from small near-axis seamounts and two larger near-ridge seamount chains for trace elements and Sr-Nd-Pb isotopes: the Lamont Seamounts adjacent to the East Pacific Rise (EPR) ~ 10°N and the Vance Seamounts next to the Juan de Fuca Ridge (JdFR) ~45°N. One purpose of the study is to test the hypothesis that near ridge seamount chains reflect focusing of melts by dunite channels in the upwelling asthenospheric mantle and that such conduits might affect melting in the shallow mantle (Lundstrom et al., 2000). Our results indicate that lavas from these seamounts have incompatible trace element patterns varying from very depleted to moderately enriched (found at the oldest, most distant Vance seamounts) relative to typical mid-ocean ridge basalts (MORB). Trace element compositions and Sr-Nd-Pb isotope data show that lava compositions vary significantly between seamounts in the chain as well as within individual seamounts. Overall, the Vance and Lamont seamount lavas are more primitive and diverse than associated ridge samples. These variations can be explained by multiple sources as well as different extents of melting, and are unlikely to reflect shallow level fractional crystallization. Sr-Nd-Pb isotope data also indicate some mixing between mantle end members. The significant variations in incompatible trace element and isotopic compositions that are somewhat correlated suggest that the mantle underneath the seamounts is heterogeneous on a small scale. The fact that

  1. Deformation and faulting of subduction overriding plate caused by a subducted seamount

    NASA Astrophysics Data System (ADS)

    Ding, Min; Lin, Jian

    2016-09-01

    We conducted numerical experiments to simulate elastoplastic deformation of the overriding plate caused by a subducted seamount. Calculations revealed development of a distinct pair of fault-like shear zones, including a landward dipping forethrust fault initiated from the seamount top and a seaward dipping backthrust fault from the landward base of the seamount. Significant dome-shaped surface uplift was predicted above the thrust faults. Lesser-developed seaward dipping backthrust faults were calculated to develop under certain conditions. The overriding plate was calculated to deform in two stages: In Stage I, elastic deformation leads to the formation of fault-like shear zones. After major faults have cut through the entire plate, plastic deformation on faults dominates Stage II. On the subduction interface, compressional normal stress was calculated to increase on the landward leading flank of the seamount and decrease on the seaward trailing flank. These changes, together with associated stress singularities at seamount edges, could affect earthquake processes.

  2. Seasonal Variation in Meteor Decay Time Profiles Measured by a Meteor Radar at King Sejong Station (62°S, 58°W), Antarctica

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, J.; Lee, C.; Jee, G.

    2008-12-01

    A VHF meteor radar at King Sejong Station (62°S, 58°W), Antarctica has been detecting echoes from more than 20,000 meteors per day since March 2007. Meteor echoes are decayed typically within seconds as meteor trail plasma spread away or are neutralized. Assuming that diffusion is the only process for decay of meteor echo signals, the atmospheric temperatures and pressures have been inferred from the measured meteor decay times at the peak meteor altitudes around 90 km. In this study, we analyze altitude profiles of meteor decay times in each month, which clearly show a maximum at 80 ~ 85 km. The maximum appears at higher altitude during austral summer than winter. The fast decay of meteor signals below the maximum cannot be explained by atmospheric diffusion which decreases with increasing atmospheric densities. We find that the measured meteor decay time profiles can be fitted with a loss rate profile, in addition to diffusion, with a peak altitude of 55 ~ 73 km and a peak rate of 4 ~ 15 sec- 1. The additional loss of meteor plasma may be due to electron absorption by icy particles in the mesosphere, but the estimated peak altitudes are much lower than the layers of NLC or PME. The estimated peak loss rates seem to be too large to be accounted by absorption by icy or dust particles. We will discuss other processes to explain the fast meteor times and their variation over season.

  3. The ecology of xenophyophores (Protista) on eastern Pacific seamounts

    NASA Astrophysics Data System (ADS)

    Levin, Lisa A.; Thomas, Cynthia L.

    1988-12-01

    Large, agglutinating protozoans of the class Xenophyophorea are the dominant epifaunal organisms on soft and hard substrates of many bathyal seamounts in the eastern Pacific Ocean off Mexico. Observations made with the submersible Alvin and remotely towed camera sleds on 17 seamounts at 31°, 20°, 13° and 10°N revealed more than ten distinct xenophyophore test morphologies. Most of these appear to represent previously undescribed species. Reticulate forms are numerically dominant at 20°, 13° and 10°N. Xenophyophore abundances increase with decreasing latitude, being rare at 30°N, present at densities of 0.1-1.0 m -2 at 20° and 13°N and often exceeding 1.0 m -2 at 10°N, occasionally reaching 10-18 m -2. Highest concentrations are observed on caldera floors near the base of steep caldera walls, at depths between 1700 and 2500 m. Most individuals select sand-size pelagic foraminiferan tests (63-500 μm) and exclude pebble, silt and clay-size particles for test construction. Xenophyophore on seamounts modify the structure of metazoan communities and may play a role in maintenance of infaunal diversity. Twenty-seven xenophyophore tests were found to provide habitat for 16 major macrofaunal taxa (152 individuals) and three meiofaunal taxa (333 individuals). The presence of xenophyophores also enhances the abundance of isopods, tanaids, ophiuroids, nematodes and harpacticoid copepods dwelling in sediments surrounding the tests. Mobile megafauna are attracted to sediment beneath and adjacent to xenophyophores. We suggest that xenophyophores, which are abundant on many topographic features in deep water (e.g. guyots, trenches, canyons and continental slopes), are a functionally important component of deep-sea benthic communities and require further autecological and synecological investigation.

  4. Seismic Stratigraphy of Detroit Seamount: Observations From ODP Leg 197

    NASA Astrophysics Data System (ADS)

    Kerr, B. C.; Scholl, D. W.

    2002-12-01

    In July-August of 2001, ODP Leg 197 drilled Detroit Seamount of the Emperor seamount chain to obtain cores of basaltic lava flows. Prior to drilling, the JOIDES Resolution, performed high-resolution single-channel seismic surveys in the vicinity of preliminary site locations to help confirm suitability for drilling, and to collect digital seismic data. At least two seismic lines (about 10 km in length) cross directly over each of the two drill sites. On Detroit Seamount, a significant west-northwest-striking normal fault occurs in the basement with the hanging wall to the northeast. The apparent offset in the basement increases to the northwest from approximately 160 m to nearly 450 m. Normal faults with offsets on the order of tens of meters occur to the north east of the primary basement escarpment. Upward termination of sediment reflections near the escarpment suggests concurrent faulting and deposition. The lower section of the Meiji sediment drift sequence appears to have been blown over the basement topography, suggesting the faulted basement could have been channeling flow of the Meiji current. A channel in sea floor topography coincides with the faulted basement. The topography of the sediment bedforms also exhibit large amplitudes deep in the section, which decrease in amplitude higher up in section, indicating that the sediment is not simply settling to the ocean floor, but is being transported and deposited along the sea floor. Currently, we are generating synthetic seismograms using physical properties and logging tool measurements from ODP Sites 883, 1203, and 1204. The synthetic seismograms will help correlate reflections from sedimentary and volcanic units with the stratigraphy observed at the drill sites.

  5. 3-D modelling of seamount topography from satellite altimetry

    SciTech Connect

    Baudry, N. ); Calmant, S. )

    1991-06-01

    The authors develop a complete set of algorithms to perform 3D modelling of seamount bathymetry from satellite altimetry. The first stage of the data processing consists in gridding the geoid: to account for the long wavelength errors geoid heights are first bias-adjusted at cross-overs. Then a collocation on a regular grid is performed, accounting for the altimeter errors. In a second stage, geoid heights are converted into bathymetry. No simplifying assumption on the shape and location of the bathymetry highs is necessary. Bathymetric uncertainties due to the data sampling and the parameters of the mechanical and crustal models are evaluated.

  6. Upward-moving low-light meteor. I: Observation results

    NASA Astrophysics Data System (ADS)

    Kozak, P. M.; Watanabe, J.

    2017-01-01

    The results of TV-detecting an earth-atmosphere-grazing low-light meteor are presented. The meteor was registered near Kyiv, Ukraine, on 23 September 2003 at UT = 20:55:52 during the Autumn Equinox observations. It was registered with both observational cameras within the altitude range H ≈ 115.6 div 117.9 km (Δ {H} ≈ - 2.3 km), the zenith distance of its radiant varying within the bounds of {Z_R} ≈ 93.7° div 94.0°. After 3D reconstruction of the trajectory, the perigee distance of the meteor was found {R_P} ≈ {{6467}}{{.4}} km, while the altitude of the minimal encounter with earth above sea level was{H_P} = 101.7 km. Traveling with the velocity of {υ}_{∞} ≈ 62.9 km/s, the meteor reached the view fields of the cameras ˜426 km after the perigee (˜6.8 s), and left them at the height of ˜461 km, practically not changing its absolute magnitude which varied in the range of {2.9^m} div {4.1^m} . Thus, the meteor remained inside the view fields of the cameras for ˜0.5 s, passing the distance of ˜35˜ km during this time. The right ascension and declination of geocentric radiant of the meteor before perigee were {α _G} ≈ 79.3°, {δ _G} ≈ - 4.2° accordingly, and the geocentric velocity {υ_G} ≈ 61.9 km/s, while after the perigee {α _G} ≈ 78.1°, {δ _G} ≈ - 2.8°, and {υ_G} ≈ 61.9 km/s (the atmosphere deceleration was neglected). The computations of heliocentric orbit elements of the meteor led to the conclusion that the meteoroid does not belong to any known meteor streams. While traveling through the view fields of the cameras, the meteor lost the mass of ˜ 5 × 10-3 g. Since the meteor was registered at the heights where ablation must become lower and eventually stop, one can assert that the meteoroid left the earth atmosphere saving part of its mass.

  7. Upward-moving low-light meteor. I: Observation results

    NASA Astrophysics Data System (ADS)

    Kozak, P. M.; Watanabe, J.

    2017-01-01

    The results of TV-detecting an earth-atmosphere-grazing low-light meteor are presented. The meteor was registered near Kyiv, Ukraine, on 23 September 2003 at UT = 20:55:52 during the Autumn Equinox observations. It was registered with both observational cameras within the altitude range H ≈ 115.6 div 117.9 km (Δ H ≈ - 2.3 km), the zenith distance of its radiant varying within the bounds of Z_R ≈ 93.7° div 94.0°. After 3D reconstruction of the trajectory, the perigee distance of the meteor was found R_P ≈ 6467.4 km, while the altitude of the minimal encounter with earth above sea level was H_P = 101.7 km. Traveling with the velocity of υ_∞ ≈ 62.9 km/s, the meteor reached the view fields of the cameras ˜426 km after the perigee (˜6.8 s), and left them at the height of ˜461 km, practically not changing its absolute magnitude which varied in the range of 2.9^m div 4.1^m. Thus, the meteor remained inside the view fields of the cameras for ˜0.5 s, passing the distance of ˜35˜ km during this time. The right ascension and declination of geocentric radiant of the meteor before perigee were α_G ≈ 79.3°, δ_G ≈ - 4.2° accordingly, and the geocentric velocity υ_G ≈ 61.9 km/s, while after the perigee α_G ≈ 78.1°, δ _G ≈ - 2.8°, and υ_G ≈ 61.9 km/s (the atmosphere deceleration was neglected). The computations of heliocentric orbit elements of the meteor led to the conclusion that the meteoroid does not belong to any known meteor streams. While traveling through the view fields of the cameras, the meteor lost the mass of ˜ 5 × 10-3 g. Since the meteor was registered at the heights where ablation must become lower and eventually stop, one can assert that the meteoroid left the earth atmosphere saving part of its mass.

  8. Tidal influence on particulate organic carbon export fluxes around a tall seamount

    NASA Astrophysics Data System (ADS)

    Turnewitsch, Robert; Dumont, Matthew; Kiriakoulakis, Kostas; Legg, Sonya; Mohn, Christian; Peine, Florian; Wolff, George

    2016-12-01

    As tall seamounts may be 'stepping stones' for dispersion and migration of deep open ocean fauna, an improved understanding of the productivity at and food supply to such systems needs to be formed. Here, the 234Th/238U approach for tracing settling particulate matter was applied to Senghor Seamount - a tall sub-marine mountain near the tropical Cape Verde archipelago - in order to elucidate the effects of topographically-influenced physical flow regimes on the export flux of particulate organic carbon (POC) from the near-surface (topmost ⩽ 100 m) into deeper waters. The comparison of a suitable reference site and the seamount sites revealed that POC export at the seamount sites was ∼2-4 times higher than at the reference site. For three out of five seamount sites, the calculated POC export fluxes are likely to be underestimates. If this is taken into account, it can be concluded that POC export fluxes increase while the passing waters are advected around and over the seamount, with the highest export fluxes occurring on the downstream side of the seamount. This supports the view that biogeochemical and biological effects of tall seamounts in surface-ocean waters might be strongest at some downstream distance from, rather than centred around, the seamount summit. Based on measured (vessel-mounted ADCP) and modelled (regional flow field: AVISO; internal tides at Senghor: MITgcm) flow dynamics, it is proposed that tidally generated internal waves result in a 'screen' of increased rates of energy dissipation that runs across the seamount and leads to a combination of two factors that caused the increased POC export above the seamount: (1) sudden increased upward transport of nutrients into the euphotic zone, driving brief pulses of primary production of new particulate matter, followed by the particles' export into deeper waters; and (2) pulses of increased shear-driven aggregation of smaller, slower-settling into larger, faster-settling particles. This study

  9. The Effect of Plate Structure on Intraplate Volcanism, Kodiak-Bowie Seamount Chain, Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Reece, R. S.; Christeson, G. L.; Gulick, S. S.; Barth, G. A.; Van Avendonk, H. J.

    2012-12-01

    Newly acquired ocean bottom seismometer (OBS) and multi-channel seismic (MCS) data in the vicinity of the Kodiak-Bowie Seamount Chain and Aja Fracture Zone reveal the character and structure of the Pacific Plate, overlying sediment, and seamounts in the Gulf of Alaska. Our data include two marine wide-angle OBS profiles, two coincident MCS profiles, and several nearby MCS profiles, including lines parallel to and crossing the Seamount Chain and Fracture Zone. This new data may help to reveal the character of the Kodiak-Bowie Seamount Chain and associated intraplate volcanism, much of which is concealed by the Surveyor and Baranof sedimentary fan systems. The Kodiak-Bowie Seamount Chain stretches over 1000 km across the Gulf of Alaska, from the Aleutian Trench in the northwest to offshore Queen Charlotte Islands in the southeast. The ages of the seamounts range from 24 Ma at Kodiak Seamount in the northwest to ≥0.7 Ma at Bowie Seamount in the southeast. Although the seamounts are largely age-progressive, some members of the chain are dated significantly out of sequence. Previous studies suggest the possibility that the majority of seamounts in the chain could be products of the Bowie plume. The Gulf-wide Aja Fracture Zone intersects the Kodiak-Bowie Seamount Chain in the central Gulf at the location of the seismic lines. Preliminary tomographic inversions of the seismic data reveal significant changes in crustal thickness across the Aja Fracture Zone, including at least a 3 km step up in the moho from south to north. Additionally, the region north of the Fracture Zone exhibits a 3 km thick low velocity zone in the upper crust, which is double the thickness of the same feature south of the fracture zone. This low velocity zone in the upper crust may be representative of intraplate volcanism associated with the Kodiak-Bowie Chain; several higher velocity perturbations within this zone are coincident with the locations of major seamounts. We will further refine

  10. In the Footsteps of Charles Darwin: Patterns of Coastal Subsidence and Uplift Associated with Seamount Subduction, Basal Fore-arc Erosion and Seamount Accretion in Latin America

    NASA Astrophysics Data System (ADS)

    Fisher, D. M.; Kirby, S. H.; David, S. W.

    2004-12-01

    In Geological Observations on South America (1846), Charles Darwin described beds of late Cenozoic marine seashells that were uplifted to elevations as much as several hundred meters above some localities on the western coastline of South America and implied that the whole coast was uplifting at geologic time scales. We know now that such evidence is generally restricted to coastal embayments above fore-arc basins where offshore seamounts are colliding with the South American fore arc (e.g., the Juan Fernandez seamount chain, Valpariso Basin and Valpariso Bay). We suggest that the phenomena of basal fore-arc erosion and basin formation and coastal uplift are closely related to effects of seamount subduction. Marine multibeam sonar images and multichannel seismic reflection surveys by others demonstrate that seamounts, although locally cut by normal faults in the outer-rise/near-trench region, initally subduct intact and the primary interaction with the toe of the fore arc is plowing, with material eroded from the fore arc that accumulates above and on the margins of the seamount. Submarine landslides above such regions over-steepened by plowing can lead to coastal embayments far upslope of the plowing. Such plowing interaction can therefore lead to the formation of large forearc basins and coastal embayments such as those at Valpariso, Chile, or narrow corridors of subsidence in the wake of subducting seamounts in Costa Rica. It is also known that the transition between interplate thrust seismicity, representing mechanical coupling between the plates, and aseismic slip occurs at depths of typically 30-60 km and often geographically near coastlines that mark the boundary between outer fore-arc subsidence and inner fore-arc uplift. We suggest that decoupling can occur at the base of seamounts (i.e., the originally sedimented seafloor on which the seamount lavas are laid down) and that such seamounts can be accreted to the fore arc above and lead to coastal uplift

  11. Tidal currents and anticyclonic motions on two North Pacific seamounts

    USGS Publications Warehouse

    Genin, A.; Noble, M.; Lonsdale, P.F.

    1989-01-01

    Near-bottom currents were measured for several days at three sites on the summits of Fieberling Guyot (32??26???N, 127??46???W) and Horizon Guyot (19??15???N, 160??00???W). Three moorings comprised of two current meters were deployed on each summit; two moorings were deployed on opposite sides of the rim of the summit and one mooring was deployed near the center of the summit. The observed currents were strong, with maximum speeds of 48 and 24 cm s-1 on Fieberling and Horizon, respectively. The currents at specific frequencies were enhanced relative to those in the surrounding ocean. Diurnal currents were the dominant component of the current field on Fieberling Guyot. They accounted for 39-68% of the energy and had amplitudes around 12 cm s-1. We suspect that these diurnal currents were waves trapped over the seamount. Semidiurnal internal tidal currents were the strongest currents over Horizon Guyot, with amplitudes around 4 cm s-1. The flow patterns determined in this study seemed to affect the biological and geological characteristics of the seamounts. ?? 1990.

  12. Dynamical Model for the Toroidal Sporadic Meteors

    NASA Astrophysics Data System (ADS)

    Pokorný, Petr; Vokrouhlický, David; Nesvorný, David; Campbell-Brown, Margaret; Brown, Peter

    2014-07-01

    More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.

  13. Dynamical model for the toroidal sporadic meteors

    SciTech Connect

    Pokorný, Petr; Vokrouhlický, David; Nesvorný, David; Campbell-Brown, Margaret; Brown, Peter E-mail: vokrouhl@cesnet.cz E-mail: margaret.campbell@uwo.ca

    2014-07-01

    More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.

  14. Automated Optical Meteor Fluxes and Preliminary Results of Major Showers

    NASA Technical Reports Server (NTRS)

    Blaauw, R.; Campbell-Brown, M.; Cooke, W.; Kingery, A.; Weryk, R.; Gill, J.

    2014-01-01

    NASA's Meteoroid Environment Office (MEO) recently established a two-station system to calculate daily automated meteor fluxes in the millimeter-size-range for both single-station and double-station meteors. The cameras each consist of a 17 mm focal length Schneider lens (f/0.95) on a Watec 902H2 Ultimate CCD video camera, producing a 21.7x15.5 degree field of view. This configuration sees meteors down to a magnitude of +6. This paper outlines the concepts of the system, the hardware and software, and results of 3,000+ orbits from the first 18 months of operations. Video from the cameras are run through ASGARD (All Sky and Guided Automatic Real-time Detection), which performs the meteor detection/photometry, and invokes MILIG and MORB (Borovicka 1990) codes to determine the trajectory, speed, and orbit of the meteor. A subroutine in ASGARD allows for approximate shower identification in single-station detections. The ASGARD output is used in routines to calculate the flux. Before a flux can be calculated, a weather algorithm indicates if sky conditions are clear enough to calculate fluxes, at which point a limiting magnitude algorithm is employed. The limiting stellar magnitude is found using astrometry.net (Lang et al. 2012) to identify stars and translated to the corresponding shower and sporadic limiting meteor magnitude. It is found every 10 minutes and is able to react to quickly changing sky conditions. The extensive testing of these results on the Geminids and Eta Aquariids is shown. The flux involves dividing the number of meteors by the collecting area of the system, over the time interval for which that collecting area is valid. The flux algorithm employed here differs from others currently in use in that it does not make the gross oversimplication of choosing a single height to calculate the collection area of the system. In the MEO system, the volume is broken up into a set of height intervals, with the collecting areas determined by the position of the

  15. Temporal patterns in the acoustic signals of beaked whales at Cross Seamount.

    PubMed

    Johnston, D W; McDonald, M; Polovina, J; Domokos, R; Wiggins, S; Hildebrand, J

    2008-04-23

    Seamounts may influence the distribution of marine mammals through a combination of increased ocean mixing, enhanced local productivity and greater prey availability. To study the effects of seamounts on the presence and acoustic behaviour of cetaceans, we deployed a high-frequency acoustic recording package on the summit of Cross Seamount during April through October 2005. The most frequently detected cetacean vocalizations were echolocation sounds similar to those produced by ziphiid and mesoplodont beaked whales together with buzz-type signals consistent with prey-capture attempts. Beaked whale signals occurred almost entirely at night throughout the six-month deployment. Measurements of prey presence with a Simrad EK-60 fisheries acoustics echo sounder indicate that Cross Seamount may enhance local productivity in near-surface waters. Concentrations of micronekton were aggregated over the seamount in near-surface waters at night, and dense concentrations of nekton were detected across the surface of the summit. Our results suggest that seamounts may provide enhanced foraging opportunities for beaked whales during the night through a combination of increased productivity, vertical migrations by micronekton and local retention of prey. Furthermore, the summit of the seamount may act as a barrier against which whales concentrate prey.

  16. Seasonal changes in fish assemblage structure at a shallow seamount in the Gulf of California.

    PubMed

    Jorgensen, Salvador J; Klimley, A Peter; Muhlia-Melo, Arturo; Morgan, Steven G

    2016-01-01

    Seamounts have generally been identified as locations that can promote elevated productivity, biomass and predator biodiversity. These properties attract seamount-associated fisheries where elevated harvests can be obtained relative to surrounding areas. There exists large variation in the geological and oceanographic environment among the thousands of locations that fall within the broad definition of seamount. Global seamount surveys have revealed that not all seamounts are hotspots of biodiversity, and there remains a strong need to understand the mechanisms that underlie variation in species richness observed. We examined the process of fish species assembly at El Bajo Espiritu Santo (EBES) seamount in the Gulf of California over a five-year study period. To effectively quantify the relative abundance of fast-moving and schooling fishes in a 'blue water' habitat, we developed a simplified underwater visual census (UVC) methodology and analysis framework suitable for this setting and applicable to future studies in similar environments. We found correlations between seasonally changing community structure and variability in oceanographic conditions. Individual species responses to thermal habitat at EBES revealed three distinct assemblages, a 'fall assemblage' tracking warmer overall temperature, a 'spring assemblage' correlated with cooler temperature, and a 'year-round assemblage' with no significant response to temperature. Species richness was greatest in spring, when cool and warm water masses stratified the water column and a greater number of species from all three assemblages co-occurred. We discuss our findings in the context of potential mechanisms that could account for predator biodiversity at shallow seamounts.

  17. Generation of mesoscale hydrodynamic phenomena by the Grappler and Whiting Seamounts, southeast of Puerto Rico

    SciTech Connect

    Capella, J.E.

    1983-01-01

    This work presents the results of research on topographically generated mesoscale eddies in the region of the Grappler and Whiting Seamounts which are located 22 km southeast of Puerto Rico. Three different data sets were used: (1) site specific hydrographic data, (2) satellite images from TIROS/NOAA, Landsat and Skylab satellites, and (3) free-drifting drogued-buoy tracks. A reference current meter station was established at the Benchmark B OTEC site (17/sup 0/ 57.3' N, 65/sup 0/ 51.5' W), at a depth of 20 meters. Predictions from numerical and analytical models were tested using the site specific data and then compared to experimental results. The hydrographic and drogue data definitively establish the presence of perturbations over the seamounts which are qualitatively consistent with model predictions. Closed contour regions in the distribution of dynamic heights, temperature, salinity and dissolved oxygen were found in the surface and subsurface waters above the top of Grappler Seamount. Horizontal flow perturbations, detected down to 100m, probably extend deeper. Whiting Seamount's effect was detected in the depth range from 200 to 300m, also near its top. Two distinct warm and cold regions were detected over this seamount. A cyclonic eddy-like feature located close to Grappler Seamount, in the satellite images, also suggests that eddies are being shed from the seamount region. 42 refs., 22 figs., 3 tabs.

  18. Prokaryote diversity and viral production in deep-sea sediments and seamounts

    NASA Astrophysics Data System (ADS)

    Danovaro, Roberto; Corinaldesi, Cinzia; Luna, Gian Marco; Magagnini, Mirko; Manini, Elena; Pusceddu, Antonio

    2009-05-01

    Despite the fact that marine prokaryotes and viruses have been increasingly investigated over the last decade, knowledge on prokaryote diversity and viral production in bathyal sediments is limited. We investigated microbial variables in the deep-sea sediments around two seamounts at 3000-m depth in the Tyrrhenian Sea and sediments located at the same depth, but not affected by the presence of the seamounts. We hypothesized that seamounts altered significantly prokaryotes-viruses interactions in surrounding deep-sea sediments. Sediments surrounding seamounts were characterised by prokaryotic abundances significantly higher than those observed in non-seamount sediments. Benthic viral production was about double in sediments close to seamounts than in non-seamount sediments, where virus turnover was up to 3 times lower. Total Bacteria, as assessed by CARD-FISH, dominated prokaryotic community structure, whereas Archaea accounted on average for approximately 10%. The fraction of Crenarchaeota was always higher than Euryarchaeota. Bacterial diversity, estimated using ARISA, was high, with up to 127 different microbial operational taxonomic units (OTUs) in a single sample. Archaeal richness (determined using T-RFLP of the 16S rRNA gene) ranged from 12 to 20 OTUs, while Archaeal evenness was comprised between 0.529±0.018 and 0.623±0.08. Results represent a pointer for future investigations dealing with the interactions between viruses and prokaryotes in deep-sea sediments.

  19. Division F Commission 22: Meteors, Meteorites, and Interplanetary Dust

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter; Borovička, Jiří; Watanabe, Jun-Ichi; Jopek, Tadeusz; Abe, Shinsuke; Consolmagno, Guy J.; Ishiguro, Masateru; Janches, Diego; Ryabova, Galina O.; Vaubaillon, Jérémie; Zhu, Jin

    2016-04-01

    Commission 22 (Meteors, Meteorites and Interplanetary Dust) was established at the first IAU General Assembly held in Rome in 1922, with William Frederick Denning as its first President. Denning was an accountant by profession, but as an amateur astronomer he contributed extensively to meteor science. Commission 22 thus established a pattern that has continued to this day that non-professional astronomers were welcomed and valued and could play a significant role in its affairs. The field of meteors, meteorites and interplanetary dust has played a disproportional role in the astronomical perception of the general public through the majestic displays of our annual meteor showers. Those in the field deployed many techniques uncommon in other fields of astronomy, studying the ``vermin of space'', the small solid bodies that pervade interplanetary space and impact Earth's atmosphere, the surface of the Moon, and that of our satellites in orbit. Over time, the field has tackled a wide array of problems, from predicting the encounter with meteoroid streams, to the origin of our meteorites and the nature of the zodiacal cloud. Commission 22 has played an important role in organizing the field through dedicated meetings, a data centre, and working groups that developed professional-amateur relationships and that organized the nomenclature of meteor showers. The contribution of Commission 22 to the field is perhaps most readily seen in the work of the presidents that followed in the footsteps of Denning.

  20. Simulating Meteor Shower Observations In The Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    McAuliffe, J. P.; Christou, A. A.

    2005-08-01

    It is known that fast meteoroids entering the martian atmosphere give rise to bright, detectable meteors (Adolfsson et al, Icarus 119, 144, 1996). Although single meteors have already been detected at Mars (Selsis et al., Nature 435, 581, 2005), the characterisation of the martian meteor year will require a large number of detections. Experience at the Earth suggests that data storage and bandwidth resources to conduct such surveys will be substantial, and may be prohibitive. In an attempt to quantify the problem in detail, we have simulated meteor shower detection in the martian and terrestrial atmospheres. For a given shower, we assume a meteoroid stream flux, size distribution and velocity based on current knowledge of Earth streams as well as the proximity of certain comets' orbits to that of Mars. A numerical code is used to simulate meteoroid ablation in a model martian and terrestrial atmosphere. Finally, using the same baseline detector characteristics (limiting magnitude, sky coverage) we generate detection statistics for the two planets. We will present results for different types of showers, including strong annual activity and episodic outbursts from Halley-type and Jupiter family comets. We will show how detection efficiency at Mars compares to the Earth for these showers and discuss optimum strategies for monitoring the martian atmosphere for meteor activity. Astronomy research at Armagh Observatory is funded by the Northern Ireland Department of Culture, Arts and Leisure (DCAL).

  1. Long duration meteor echoes characterized by Doppler spectrum bifurcation

    NASA Astrophysics Data System (ADS)

    Bourdillon, A.; Haldoupis, C.; Hanuise, C.; Le Roux, Y.; Menard, J.

    2005-03-01

    We report on a new category of long lasting meteor echoes observed occasionally with HF and VHF radars. These meteoric returns, which have lifetimes from many seconds to a few minutes, are characterized by a distinct Doppler spectral signature showing a pronounced Doppler bifurcation which includes narrow bands of discrete Doppler velocities, often of opposite polarity. The large signal to noise ratios and the narrowness of the spectra imply that coherent or Bragg scattering is not of relevance here, therefore these echoes do not associate with the long living meteor-induced backscatter (MIB) from the lower E region. A reasonable interpretation needs to explain both the Doppler spectrum bifurcation and the long echo duration. As such, we propose the idea of a structured vertical wind shear in the lower E region which traps different fragments of a meteor trail plasma in the same way that sporadic E layers form. These trail parts inside the shear-related wind profile may act as relatively long-lasting meteoric reflectors moving with different Doppler velocities, also of opposite polarity.

  2. Largest meteor since Tunguska event explodes above Russian city

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-02-01

    The meteor that disintegrated in the atmosphere above Chelyabinsk, Russia, on 15 February, injuring more than 1000 people and causing widespread property damage from the shock wave, is the largest such incident since the 1908 Tunguska event in Siberia, according to Paul Chodas, research scientist in the Near-Earth Object (NEO) program office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. During a 15 February teleconference, Chodas said it was an "incredible coincidence" that asteroid DA14 passed safely by Earth on the same day as the Chelyabinsk meteor; the 45-meter-wide asteroid sped by the planet at a distance of just 27,700 kilometers away on its closest approach. He stressed that the meteor was not related to DA14. The meteor "was coming from the wrong direction and at a completely different velocity," he said, noting that the orbit of the meteor went out to the asteroid belt while the orbit of DA14 "is very Earth-like, it does not go out so far."

  3. Petrology and tectonic significance of seamounts within transitional crust east of Orphan Knoll, offshore eastern Canada

    NASA Astrophysics Data System (ADS)

    Pe-Piper, Georgia; Meredyk, Shawn; Zhang, Yuanyuan; Piper, David J. W.; Edinger, Evan

    2013-12-01

    The Early Cretaceous separation of Newfoundland from Iberia-Ireland is a classic example of a magma-poor continental margin with hyperextension and with widespread minor magmatism resulting in seamounts. This study defines the distribution of seamounts east of Orphan Knoll, and documents and interprets the geochemical character of the one recovered lava sample. Video imagery of lava outcrops, and the sample, were obtained by ROV from Orphan seamount, one of a linear series of small seamounts overlying transitional thinned continental crust on the seaward side of Orphan Knoll. New multibeam bathymetry and legacy seismic data show several seamounts that extend irregularly along the fault-bound NE margin of Orphan Knoll. Whole rock geochemistry shows the sample to be highly alkaline basanite or possibly tephrite. Diopside-hedenbergite, kaersutite and K-feldspar phenocrysts were analyzed by electron microprobe and scanning electron microscope, and alteration minerals including kaolinite were identified by X-ray diffraction. The highly alkaline character of the basanite is similar only to Early Cretaceous volcanic and sub-volcanic rocks erupted through thick continental crust of the Mesoproterozoic Grenville Orogeny. The location of the linear set of seamounts is related to margin-parallel faults on the seaward side of Orphan Knoll that provided a pathway for magma, although ENE-trending lineaments in individual seamounts or seamount groups suggest the influence of oceanic fracture zones. A lower gradient crest to Orphan seamount above 2,200 m suggests subaerial erosion, consistent with the presence of kaolinite as an alteration product and the absence of lava pillows at and above this depth.

  4. Meteoric 10Be in soil profiles - A global meta-analysis

    USGS Publications Warehouse

    Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.

    2010-01-01

    In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric 10Be in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10Be distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric 10Be. Percent organic carbon and pH are not significantly related to meteoric 10Be concentration when all data are complied.The compilation shows that meteoric 10Be concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric 10Be concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric 10Be concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric 10Be concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric 10Be concentration correlate with the total measured meteoric 10Be inventory of the soil profile.In order to refine the use of meteoric 10Be as an estimator of soil erosion rate, we compare near-surface meteoric 10Be concentrations to total meteoric 10Be soil inventories. These trends are used to calibrate models of meteoric 10Be loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.

  5. Phytoplankton and nutrient dynamics of six South West Indian Ocean seamounts

    NASA Astrophysics Data System (ADS)

    Sonnekus, Martinus J.; Bornman, Thomas G.; Campbell, Eileen E.

    2017-02-01

    A survey of six seamounts and two transects through the subtropical convergence zone (SCZ) in the South Indian Ocean in November and December 2009 showed a strong latitudinal gradient from the subtropics to the Sub-Antarctic Front. Concentrations of oxygen, nitrate, nitrite, soluble reactive phosphorous as well as phytoplankton biomass (measured as chlorophyll a) increased while salinity and temperature decreased with an increase in latitude. These differences resulted in significant differences between seamounts. The chlorophyll a maximum became shallower at higher latitudes, changing from a depth of 85 m in the subtropics to 35 m over the seamounts and in the SCZ. The mixed layer depth also increased from 50 m in the subtropics to 100 m at higher latitude stations. The N:P and N:Si ratio indicated that NO3- was limiting at all the seamounts except one, at which SiO4 was the limiting nutrient. The phytoplankton community also showed a latitudinal gradient with decreasing diversity and a change in dominance from dinoflagellates in the tropics to diatoms towards the SCZ. The dominant diatom genus of the survey (>50% of the cell counts) was Pseudo-nitzschia. Nutrients exhibited an inverse linear relationship with temperature and salinity. The oligotrophic subtropical areas differed from the mesotrophic seamounts in temperature while waters over seamounts north and south of the Agulhas Return Current (ARC) differed in salinity. The phytoplankton (148 taxa) responded to these differences, showing three communities: subtropical seamount phytoplankton (Atlantis Seamount, Walters Seamount and off-mount samples), phytoplankton of the waters north of the ARC (Melville Bank, Sapmer Bank, Middle of What Seamount) and phytoplankton south of the ARC (Coral Seamount, SCZ1) characterised by a bloom of Phaeocystis antarctica. The environmental drivers most strongly linked to these observed differences were nitrate, temperature and oxygen. These environmental drivers displayed a

  6. Meteoric-like fabrics forming in marine waters. Implications for the use of petrography to identify diagenetic environments

    SciTech Connect

    Melim, L.A.; Swart, P.K.; Maliva, R.G.

    1995-08-01

    Petrographic fabrics have long been used to identify meteoric diagnesis of carbonate sediments. However, on the basis of oxygen isotopic data, we document similar fabrics forming in marine pore fluids in the shallow subsurface of Great Bahama Bank. Therefore, petrographic fabrics alone are not reliable indicators of diagenetic environments, even for shallow-water sediments. In our study, skeletal grainstones show two distinct diagenetic assemblages: either dissolution of aragonitic grains and minimal cementation (high-permeability intervals) or abundant blocky spar cement and neomorphism of aragonitic skeletal grains (low-permeability intervals). These marine-burial fabrics are present as shallow as 110 m below sea level, well above the aragonite compensation depth, a feature that must be considered for models of diagenesis in ancient carbonate sediments. Marine-burial diagenesis may be important in ancient carbonate sediments deposited in moderate water depths or in shallow water during rising sea level where meteoric diagenesis is suppressed. 17 refs., 5 figs.

  7. Morphology, petrography, age and origin of Fogo Seamount chain, offshore eastern Canada

    NASA Astrophysics Data System (ADS)

    Pe-Piper, G.; de Jonge, A.; Piper, D. J. W.; Jansa, L. F.

    2003-04-01

    The Fogo Seamounts are located approximately 500 km offshore from Newfoundland to the southwest of the Grand Banks of Newfoundland. This complex seamount chain is early Cretaceous in age and is partially buried under later continental slope deposits. It has in the past been ascribed to the passage of a Canary or Azores hot spot. The seamounts are developed along the northeastern transform margin of the Jurassic central Atlantic Ocean. The Narwhal F-99 well was drilled in 1986 on the continental slope into one buried seamount. In this study, we bring together unpublished data on the bathymetry, seismic-reflection character, and distribution of the Fogo Seamounts and interpret new petrographic, geochemical, isotopic and geochronological data from a dredge sample from the central part of the seamount chain and from the Narwhal F-99 well, making comparisons with other offshore volcanic rocks on the eastern Canadian margin. Petrographically, the seamount samples consist of vitrophyric basalt, with clinopyroxene at Narwhal and kaersutite in the dredge sample. Chemically, the samples are olivine basalt with a low Mg number and low concentration of transition metals. Trace element and REE abundances are similar to those of other early Cretaceous volcanic rocks on the southeast Canadian margin. Three petrogenetic types of mafic magma are recognised in the area. The dredge sample is typical OIB rather alkalic basalts and similar to those in other seamount chains. Rocks at Narwhal and Brant have a greater signature of a depleted mantle source (are more tholeiitic). All have Nd isotopes similar to the Newfoundland and New England seamounts. In Orpheus graben to the northwest, there appears to have been greater crustal contamination, either from the crust in the region or from mantle previously enriched in crustal contaminants. The dredge sample gave a 40Ar/39Ar age of 130.3 +/- 1.3 Ma (Hauterivian). A K/Ar age from the Narwhal F-99 well of 127 +/- 6 Ma is inconsistent with

  8. Constraining the Physical Properties of Meteor Stream Particles by Light Curve Shapes Using the Virtual Meteor Observatory

    NASA Technical Reports Server (NTRS)

    Koschny, D.; Gritsevich, M.; Barentsen, G.

    2011-01-01

    Different authors have produced models for the physical properties of meteoroids based on the shape of a meteor's light curve, typically from short observing campaigns. We here analyze the height profiles and light curves of approx.200 double-station meteors from the Leonids and Perseids using data from the Virtual Meteor Observatory, to demonstrate that with this web-based meteor database it is possible to analyze very large datasets from different authors in a consistent way. We compute the average heights for begin point, maximum luminosity, and end heights for Perseids and Leonids. We also compute the skew of the light curve, usually called the F-parameter. The results compare well with other author's data. We display the average light curve in a novel way to assess the light curve shape in addition to using the F-parameter. While the Perseids show a peaked light curve, the average Leonid light curve has a more flat peak. This indicates that the particle distribution of Leonid meteors can be described by a Gaussian distribution; the Perseids can be described with a power law. The skew for Leonids is smaller than for Perseids, indicating that the Leonids are more fragile than the Perseids.

  9. Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology

    USGS Publications Warehouse

    Ludvigson, Greg A.; Gonzalez, Luis A.; Metzger, R.A.; Witzke, B.J.; Brenner, Richard L.; Murillo, A.P.; White, T.S.

    1998-01-01

    Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO3), forms predominantly in wetland soils and sediments, and is common in the geologic record. Ancient sphaerosiderites are found in paleosol horizons within coal-bearing stratigraphic intervals and, like their modern counterparts, are interpreted as having formed in water-saturated environments. Here we report on sphaerosiderites from four different stratigraphic units, each of which has highly variable 13C and relatively stable 18O compositions. The unique isotopic trends are analogous to well-documented meteoric calcite lines, which we define here as meteoric sphaerosiderite lines. Meteoric sphaerosiderite lines provide a new means of constraining ground-water ??18O and thus allow evaluation of paleohydrology and paleoclimate in humid continental settings.

  10. Observation error propagation on video meteor orbit determination

    NASA Astrophysics Data System (ADS)

    SonotaCo

    2016-04-01

    A new radiant direction error computation method on SonotaCo Network meteor observation data was tested. It uses single station observation error obtained by reference star measurement and trajectory linearity measurement on each video, as its source error value, and propagates this to the radiant and orbit parameter errors via the Monte Carlo simulation method. The resulting error values on a sample data set showed a reasonable error distribution that makes accuracy-based selecting feasible. A sample set of selected orbits obtained by this method revealed a sharper concentration of shower meteor radiants than we have ever seen before. The simultaneously observed meteor data sets published by the SonotaCo Network will be revised to include this error value on each record and will be publically available along with the computation program in near future.

  11. French Meteor Network for High Precision Orbits of Meteoroids

    NASA Technical Reports Server (NTRS)

    Atreya, P.; Vaubaillon, J.; Colas, F.; Bouley, S.; Gaillard, B.; Sauli, I.; Kwon, M. K.

    2011-01-01

    There is a lack of precise meteoroids orbit from video observations as most of the meteor stations use off-the-shelf CCD cameras. Few meteoroids orbit with precise semi-major axis are available using film photographic method. Precise orbits are necessary to compute the dust flux in the Earth s vicinity, and to estimate the ejection time of the meteoroids accurately by comparing them with the theoretical evolution model. We investigate the use of large CCD sensors to observe multi-station meteors and to compute precise orbit of these meteoroids. An ideal spatial and temporal resolution to get an accuracy to those similar of photographic plates are discussed. Various problems faced due to the use of large CCD, such as increasing the spatial and the temporal resolution at the same time and computational problems in finding the meteor position are illustrated.

  12. Tunguska meteor fall of 1908 - Effects on stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Toon, O. B.; Park, C.; Whitten, R. C.; Pollack, J. B.; Noerdlinger, P.

    1981-01-01

    The Tunguska meteor, whose disintegration over Siberia in 1908 may have generated as much as 30 million metric tons of nitric oxide (NO) in the stratosphere and mesosphere, is discussed. The photochemical aftereffects of the event are simulated using a comprehensive model of atmospheric trace composition. Calculations are made which indicate that up to 45% of the ozone in the Northern Hemisphere may have been depleted by the meteor's nitric oxide cloud early in 1909 and that large ozone reductions may have persisted until 1912. Measurements of atmospheric transparency by the Smithsonian Astrophysical Observatory for the years 1909-1911 reveal evidence of a steady ozone recovery from unusually low levels in early 1909, implying a total ozone deficit of 30 + or - 15%. The coincidence in time between the observed ozone recovery and the Tunguska meteor fall suggests that the event may provide a test of current ozone depletion theories.

  13. Automatic Video System for Continues Monitoring of the Meteor Activity

    NASA Astrophysics Data System (ADS)

    Koten, Pavel; Fliegel, Karel; Vítek, Stanislav; Páta, Petr

    2011-05-01

    In this paper we present current progress in development of new observational instruments for the double station video experiment. The Meteor Automatic Imager and Analyser (MAIA) system is based on digital monochrome camera JAI CM-040 and well proved image intensifier XX1332. Both the observations as well as the data processing will be fully automatic. We are expecting the recorded data of better quality and both spatial and time resolution in comparison with currently used analogue system. The main goal of the MAIA project is to monitor activity of the meteor showers and sporadic meteor each night for the period of at least 3 years. First version of the system was already assembled and has been intensively tested in the optical laboratory. Optical properties were measured and the result confirmed our expectations according to image quality and resolution. First night sky observation was already carried out.

  14. Investigation of Relationships between Known Meteor Streams and Recently Recovered NEOs

    NASA Astrophysics Data System (ADS)

    Micheli, Marco; Tholen, D. J.; Elliott, G. T.; Troyer, J. M.

    2009-09-01

    In the past few years we recovered many single-opposition NEOs. A few of these objects are thought to be associated with known meteor streams, but the linkage is often unconfirmed because of a lack of precise orbital information on the parent object. The addition of a second opposition to the observed orbital arc greatly improves the predictability of their past motion, allowing us to back-integrate their orbital evolution long enough to extract meaningful predictions of associated meteoric activity. In this work we will present the results of this type of analysis on a few of these objects. The most interesting case is probably the recently recovered 2001 HA4, tentatively associated by Peter Jenniskens with the annual stream known as ω-Piscids (OPC, IAU code #217). The present radiant of the stream does not match the asteroidal orbit very well, with a declination discrepancy close to 20 degrees. With our integration we tested if old particles released in the past could match the present radiant: the discrepancy cannot be reduced by more than a few degrees, also assuming unreasonably large ejection velocities and radiation pressure effects. We also investigated the possibility of a different stream at the other node, and we found a reasonable match with the Daytime q-Pegasids (QPE, IAU code #130). Another object recovered by our team is 1997 QK1, proposed by Jenniskens as parent for the July Centaurids (JCE, IAU code #179). We checked if a compact meteor cloud associated with the object could have hit the Earth in 1896, explaining a short lived outburst observed that year from Sydney. The outburst radiant could be matched only by old and dispersed particle clouds, but not with compact recently ejected material. Acknowledgement: our observations were funded by grant AST 0709500 from the U.S. National Science Foundation.

  15. On Meteoric Dust Particles in the Near-Earth Space Environment

    NASA Astrophysics Data System (ADS)

    Mahmoudian, Alireza; Farahani, Majid Mazraeh Ei; Mohebalhojeh, Ali R.; Scales, Wayne

    2016-07-01

    Over 40 metric tons of meteoric dust enters the earth's atmosphere every day. This dust settles and creates natural dust layers in the altitude ranges between 80 and 100 kilometers which spans the earth's upper mesosphere to lower thermosphere. The dust layers in the lower atmosphere have a great impact on climate, human health as well as communication and navigation signals. The main goal of this study is the role of meteoric smoke particles on the formation of Polar Mesospheric Clouds (PMC). Recent rocket experiments have detected the presence of these particles. Since these dust layers are immersed in the earth's upper atmosphere, they become charged due to collection of electrons and ions from the earth's ionospheric plasma. Noctilucent Clouds NLCs are a fascinating visual manifestation of these dust layers. So-called Polar Mesospheric Summer Echoes PMSEs are radar echoes that are a direct consequence of the sub-visible charged dust that exists at altitudes above NLC regions. Polar Mesospheric Summer Echoes (PMSE) are strong echoes that have been typically observed in the frequency range from 50MHz to 1.3GHz and in the altitude about 85km. Unlike PMSE, Polar mesospheric winter echoes (PMWE) are less known. PMWE appear at a lower altitude and is weaker in comparison with PMSE. The focus of this study is on meteoric smoke particles and how they affect PMWE source region. Parameters associated with smoke dust particles such as size distribution, charging characteristics, density and positive or negative charge will be considered. The second part of this presentation will be on the effect of gravity waves on PMC. Full coupling to a turbulent neutral field with a statistical analysis will be discussed. Impact of a neutral turbulence driving field on small amplitude plasma fluctuations in such a configuration and some of the important consequences will be also presented. This has important consequences for electric field and potential measurements on rocket probes as

  16. UV spectroscopy of a Stardust reentry capsule as an artificial meteor

    NASA Astrophysics Data System (ADS)

    Abe, S.; Yamamoto, M.-Y.; Yano, H.; Ebizuka, N.; Watanabe, J.-I.; Mukai, T.

    On January 15 2006 an airborne observatory NASA DC-8 was flying at the eastern edge of the Nevada state line to observe an artificial meteor formed by the Stardust Sample Return Capsule SRC during its entering the earth s atmosphere The SRC observing campaign organized by NASA Ames Research Center P I Dr Peter Jenniskens was a great success The SRC emission appeared at 9 57 00 UT that was just predicted time and grew up to be a bright fire ball on the night sky Finally the SRC had a soft landing in the US Air Force s Utah Test and Training Range at 10 10 UT A spectroscopic observation in the wavelength between 300 and 650 nm together with an optical imaging observation were performed using an Image-Intensified High-Definition TV camera and WATEC video camera respectively Since the front of SRC was covered with a heat shielding ablator composed of PICA Phenolic Impregnated Carbon Ablator carbon related emission such as C 2 CN which are most likely produced from the exterior of the carbon-carbon composite material were expected It was also predicted for a main part of emission from SRC in UV region that atmospheric thermo plasma such as N 2 NH OH emissions came out from the shock front reacted with the Earth s atmosphere In this paper we present a first result of UV spectrum of an artificial meteor with its optical image The details of physical and chemical processes of SRC compared with natural meteors will be discussed

  17. A new approach to compute accurate velocity of meteors

    NASA Astrophysics Data System (ADS)

    Egal, Auriane; Gural, Peter; Vaubaillon, Jeremie; Colas, Francois; Thuillot, William

    2016-10-01

    The CABERNET project was designed to push the limits of meteoroid orbit measurements by improving the determination of the meteors' velocities. Indeed, despite of the development of the cameras networks dedicated to the observation of meteors, there is still an important discrepancy between the measured orbits of meteoroids computed and the theoretical results. The gap between the observed and theoretic semi-major axis of the orbits is especially significant; an accurate determination of the orbits of meteoroids therefore largely depends on the computation of the pre-atmospheric velocities. It is then imperative to dig out how to increase the precision of the measurements of the velocity.In this work, we perform an analysis of different methods currently used to compute the velocities and trajectories of the meteors. They are based on the intersecting planes method developed by Ceplecha (1987), the least squares method of Borovicka (1990), and the multi-parameter fitting (MPF) method published by Gural (2012).In order to objectively compare the performances of these techniques, we have simulated realistic meteors ('fakeors') reproducing the different error measurements of many cameras networks. Some fakeors are built following the propagation models studied by Gural (2012), and others created by numerical integrations using the Borovicka et al. 2007 model. Different optimization techniques have also been investigated in order to pick the most suitable one to solve the MPF, and the influence of the geometry of the trajectory on the result is also presented.We will present here the results of an improved implementation of the multi-parameter fitting that allow an accurate orbit computation of meteors with CABERNET. The comparison of different velocities computation seems to show that if the MPF is by far the best method to solve the trajectory and the velocity of a meteor, the ill-conditioning of the costs functions used can lead to large estimate errors for noisy

  18. Long-time observation of meteor induced layers with ionosonde

    NASA Astrophysics Data System (ADS)

    Yusupov, Kamil; Akchurin, Adel

    2016-07-01

    It is considered that the main theory explaining appearance of sporadic E is the theory of wind shear, which means (includes) the presence and movement of nodes converging tidal wind through the height region of the most frequent occurrence Es (120-140km) [Mathew et. all, 1998]. However, the appearance of intense layers, following its name, are sporadic, and such variability cannot to explain by the influence of tidal waves only. Another indication inconsistency theory of wind shear is the appearance of so-called transient Es layers [Maruiama, 2003]. The distinctive feature of this trace is the high critical frequency (> 5 MHz), a constant height, weak amplitude, all trace semitransparent and short lifetime [Maruiama et. all, 2003 and 2008 and references there]. Because of duration, such layer is opposite to the traditional persistent Es layer, which we do not consider in this paper. Various researchers have used different terms for such spontaneous Es, it is meteor echo, meteor induced Es, spontaneously formed sporadic Es patches resulting of the Fresnel scattering from a region of enhanced plasma density along the meteor trail, transitory Es and transient Es. Since the term transient Es is unstable, to avoid confusion, we will stick to this term. Since meteor echo is not fully satisfy this term by some parameter, we will describe the properties of transient Es based on the ionogram properties and not from physics of its origin. We used data from our ionosonde with one-minute ionogram repetition rate for 2010-2014 years. For processing performed a method are using to select beatings and the ionosphere reflectivity of the layers by means A-, H-and AΣ-map [Akchurin, 2011; Yusupov, 2014]. This maps allow to collect transient Es appearance over a long-time. Such statistics comparison with meteor showers activity showed good agreement. It shows the presence of the transient Es formation mechanism, which coupling with meteors.

  19. Towards a paleolatitude record from the Louisville Seamount trail

    NASA Astrophysics Data System (ADS)

    Gee, J. S.; Pressling, N.; Hoshi, H.; Yamazaki, T.; Scientists, E. 3; IODP Expedition 330 Scientists

    2011-12-01

    The 4300 km long Louisville Seamount trail is the South Pacific counterpart of the much better studied Hawaii-Emperor chain. Both chains are thought to reflect motion of the Pacific plate over persistent mantle melting anomalies although the stationarity of these hotspots, and thus their suitability as a reference frame for Pacific plate motions, remains uncertain. Drilling at the Emperor Seamounts documented an ~15° southward shift of the Hawaiian hotspot between about 80 and 50 Ma. IODP Expedition 330 provided the first drillcore samples from the Louisville chain, with a primary goal of documenting the paleolatitudes of seamounts with ages comparable to those drilled in the Hawaii-Emperor chain. Six sites were drilled on five Louisville guyots. The recovered materials include sediments, submarine lava flows/pillows, less abundant subaerial flows and a substantial proportion of volcaniclastic and hyaloclastite material. Sites U1374 and U1373 on Rigil Guyot (28.6°S, ~73 Ma) penetrated 522m and 66m, respectively, and yielded about thirty cooling units including both normal and reversed polarity flows. Approximately 20 normal polarity cooling units were recovered from the 233m cored interval at Site U1372 on Canopus Guyot (26.5°, ~76 Ma). Site U1376 on Burton Guyot (32.2°, ~64 Ma) penetrated 182m, with 11 reversed polarity flows. A total of 17 reversed polarity cooling units were sampled at Hadar Guyot (38.2°S, ~50 Ma) despite more limited penetration. Characteristic remanent magnetization directions were determined for more than 22,000 two-cm intervals on the archive half cores. The most reliable of these data were used to calculate average directions for individual core pieces that compare well with results from stepwise demagnetization of nearly 500 discrete samples. Because of the abundance of (mostly submarine) volcaniclastic material recovered, estimating the paleolatitude for the Louisville guyots is less straightforward than for the sites on the Hawaii

  20. A Short Cultural-Astronomical History on Asteroids, Comets and Meteors in Romania

    NASA Astrophysics Data System (ADS)

    Grigore, V.; Gheorghe, A. D.

    2012-05-01

    The poster presents significant moments in astronomy history and culture of meteors, comets and asteroids in Romania and the modern role of the Romanian Society for Meteors and Astronomy (SARM) in research, education, and culture in these fields.

  1. An Automatic Video Meteor Observation Using UFO Capture at the Showa Station

    NASA Astrophysics Data System (ADS)

    Fujiwara, Y.; Nakamura, T.; Ejiri, M.; Suzuki, H.

    2012-05-01

    The goal of our study is to clarify meteor activities in the southern hemi-sphere by continuous optical observations with video cameras with automatic meteor detection and recording at Syowa station, Antarctica.

  2. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kanq; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; Tauber, Michael E.; Venkatapathy, Ethiraj

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup. Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood. On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heat shields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kWcm2. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses.With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  3. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A.; Brandis, Aaron M.; Chen, Yih-Kanq; Jaffe, Richard L.; Saunders, David A.; Stern, Eric C.; Tauber, Michael E.; Venkatapathy, Ethiraj

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup. Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood. On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is less than 13 km/s (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/cm2. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to greater than 20 km/s; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current

  4. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kang; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; Tauber, Michael E.; Venkatapathy, Ethiraj

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup.Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood.On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/sq cm. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  5. Results of the IMO Video Meteor Network - September 2015

    NASA Astrophysics Data System (ADS)

    Molau, S.; Crivello, S.; Goncalves, R.; Saraiva, C.; Stomeo, E.; Kac, J.

    2016-02-01

    The September 2015 report of IMO Video Meteor Network observations is presented, covering more than 11 000 hours of observations with over 53 000 meteors being recorded. A recently discovered minor shower of the kappa-Cepheids cannot be identified in the 2015 Network data. The chi-Cygnids, a minor shower discovered in 2015, is confirmed based on the 2015 data, and data going back to 1999. The flux density profiles are shown for the shower for the period 2012-2015. The peak in 2015 is reached between September 14 and 17.

  6. IAU MDC Photographic Meteor Orbits Database: Version 2013

    NASA Astrophysics Data System (ADS)

    Neslušan, L.; Porubčan, V.; Svoreň, J.

    2014-05-01

    A new 2013 version of the IAU MDC photographic meteor orbits database which is an upgrade of the current 2003 version (Lindblad et al. 2003, EMP 93:249-260) is presented. To the 2003 version additional 292 orbits are added, thus the new version of the database consists of 4,873 meteors with their geophysical and orbital parameters compiled in 41 catalogues. For storing the data, a new format enabling a more simple treatment with the parameters, including the errors of their determination is applied. The data can be downloaded from the IAU MDC web site: http://www.astro.sk/IAUMDC/Ph2013/

  7. Hemispherical radiating pattern antenna design for radio meteor observation

    NASA Astrophysics Data System (ADS)

    Kákona, J.

    2016-01-01

    A highly directional pattern antenna is usually used for radio meteor observations, but these types of antennas became impractical in cases where we have multiple transmitters spread around a reception station. In that situation the hemispherical sensitivity of the antenna is more important than directional antenna gain. We present a hemispherical radiation pattern antenna design which could be modified for almost any observational frequency reflective by a meteor trail. The symmetry of the radiation pattern of such antenna allows an easy construction of antenna arrays which could be used for the angular measurement of received signals.

  8. A simplified interferometer design for use with meteor radars

    NASA Astrophysics Data System (ADS)

    Poole, L. M. G.

    2004-04-01

    A relatively simple design for a meteor radar interferometer with 4 receiving antennas is described. A basic 3 element interferometer provides a set of possible directions for each radio echo detected. The ambiguity is resolved using a 4th antenna, placed according to the results of a numerical simulation. Details of the procedure are provided. The resolution in echo direction is between ˜1° and ˜2° for altitudes (elevations) above ˜30° at all azimuths. A general purpose meteor radar based on this principle has been in use since 1986 at Grahamstown, South Africa.

  9. Meteor Orbit Determinations with Multistatic Receivers Using the MU Radar

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yasunori; Hamaguchi, Yoshiyuki; Nakamura, Takuji; Tsutsumi, Masaki; Abo, Makoto

    2008-06-01

    The MU radar of RISH (Research Institute for Sustainable Humanosphere, Kyoto University), which is a MST radar (46.5 MHz, 1 MW peak power), has been successfully applied to meteor studies by using its very high versatility. The system has recently renewed with 25 channel digital receivers which significantly improved the sensitivity and precision of interferometer used in meteor observation. The transmission is now synchronized to GPS signals, and two external receiving sites with a ranging capability has additionally been operated in order to determine the trajectories and speeds of meteoroids.

  10. Asteroidal meteors detected by MU radar head-echo observations

    NASA Astrophysics Data System (ADS)

    Abe, S.; Kero, J.; Nakamura, T.; Fujiwara, Y.; Kastinen, D.; Watanabe, J.; Hashiguchi, H.

    2016-01-01

    The recent development of the technique carried out using the middle and upper atmosphere radar (MU radar) of Kyoto University at Shigaraki (34.9N, 136.1S), which is large atmospheric VHF radar with 46.5 MHz frequency, 1 MW output transmission power and 8330 m2 aperture array antenna, has established very precise orbital determination from meteor head echoes. A tremendous number, more than 150000, of observed precise orbits of meteoroids by the MU radar meteor head-echo observation will shed light on new discoveries of meteoroids. Here we report some interesting features related with asteroids or distinct comets.

  11. About comparative models of meteor orbital data for different radars

    NASA Astrophysics Data System (ADS)

    Kolomiyets, Svitlana

    2016-07-01

    There is an electronic data base (~ 250, 000 orbits of faint radar meteors till +12^M) in the Kashcheyev LAB of KhNURE (Kharkiv, Ukraine). It is important if this data base will become open. Two scientific teams (from New Zealand and from Canada) are the principal expert on similar radar dataset (~500,000 and more than 3 million, respectively). The Kharkiv team will prepare the data for implementation in the IAU Meteor Data Centre and the virtual Observatory. We will develop a standard model for comparison of data from different radars.

  12. The METEOR trial: no rush to repair a torn meniscus.

    PubMed

    Hwang, Yong Gil; Kwoh, C Kent

    2014-04-01

    It is uncertain whether arthroscopic partial meniscectomy is better than physical therapy in patients who have a symptomatic torn meniscus on top of osteoarthritis of the knee. The Meniscal Repair in Osteoarthritis Research (METEOR) trial concluded that physical therapy is acceptable at first, and that surgery is not routinely needed. In patients assigned to physical therapy who eventually needed surgery, the delay resulting from a trial of conservative management did not impair outcomes at 12 months from the initial presentation. Here, we analyze the background, design, findings, and clinical implications of the METEOR trial.

  13. Performance of Watec 910 HX camera for meteor observing

    NASA Astrophysics Data System (ADS)

    Ocaña, Francisco; Zamorano, Jaime; Tapia Ayuga, Carlos E.

    2014-01-01

    The new Watec 910 HX model is a 0.5 MPix multipurpose video camera with up to ×256 frames integration capability. We present a sensitivity and spectral characterization done at Universidad Complutense de Madrid Instrument Laboratory (LICA). In addition, we have carried out a field test to show the performance of this camera for meteor observing. With respect to the similar model 902 H2 Ultimate, the new camera has additional set-up controls that are important for the scientific use of the recordings. However the overall performance does not justify the extra cost for most of the meteor observers.

  14. Theoretical and observational determinations of the ionization coefficient of meteors

    NASA Astrophysics Data System (ADS)

    Jones, William

    1997-07-01

    We examine the problem of the determination of the ionization coefficient beta from both the theoretical and observational points of view. In the past, theoretical evaluations of beta in terms of the relevant scattering cross-sections have used the Massey-Sida formula, which we show to give results which are plainly incorrect. We derive an integral equation for beta and compare the results of its application to copper and iron with laboratory simulations. Agreement for the variation of the ionization coefficient with velocity is good. The ionization coefficient has been determined observationally by Verniani & Hawkins from a comparison of radar and visual observations, employing the luminous efficiency tau also obtained observationally by Verniani. However, this determination of tau would appear to be invalidated by fragmentation. There is good evidence that the radiation of cometary meteors is dominated by that of iron in the visual range, and we have accordingly re-analysed the data of Verniani & Hawkins using the luminous efficiency of iron obtained in simulation experiments. However, it is not possible to choose an iron concentration which gives agreement between the determination of the ionization coefficient by this means and its determination from the theoretical equation in terms of either scattering coefficients or simulation methods. The observational ionization coefficients are much lower than predicted by the present theory and we provisionally explain this as a consequence of transfer of charge from the meteoric ion to a molecule of the air. It is now possible for the meteoric atom to be re-ionized, but it is also possible at sufficiently high initial line densities for significant dissociative recombination of the electrons and nitrogen or oxygen to take place. This recombination will not take place in meteor trains simulated in an ionization chamber. We thus conclude that the present theory is limited to faint radio meteors at lower velocities (v<~35

  15. The Cyclone meteor radar system for routine wind measurements in the lower thermosphere

    NASA Technical Reports Server (NTRS)

    Lysenko, I. A.; Mikhailiek, P. P.; Petrov, B. I.

    1987-01-01

    A new meteor wind radar system called Cyclone was devised to extend and update the meteor radar network and for unattended operation. The Cyclone meteor radar system obtains information from four directions simultaneously. To automate data processing a special digital device was developed. An algorithm used to determine the Doppler shifts was adopted, which makes it possible to eliminate selectivity with respect to slow velocity meteor drifts. The operation of the Cyclone system is described.

  16. Detecting Forward-Scattered Radio Signals from Atmospheric Meteors Using Low-Cost Software Defined Radio

    NASA Astrophysics Data System (ADS)

    Snjegota, Ana; Rattenbury, Nicholas James

    2017-02-01

    The forward scattering of radio signals from atmospheric meteors is a known technique used to detect meteor trails. This article outlines the project that used the forward-scattering technique to observe the 2015 August, September, and October meteor showers, as well as sporadic meteors, in the Southern Hemisphere. This project can easily be replicated in any part of the world and is a suitable, low-cost project designed for students who are interested in astronomy.

  17. A test of the comet hypothesis of the Tunguska Meteor Fall - Nature of the meteor 'thermal' explosion paradox

    NASA Technical Reports Server (NTRS)

    Liu, V. C.

    1978-01-01

    The hypothesis that a comet was responsible for the Tunguska Meteor Fall is rejected because the hypothesis does not seem to account for the intense terminal spherical shock. A porous meteoroid model is proposed, and an analysis indicates that an entity of this type might produce an aerodynamic heat flux large enough to account for the terminal meteor explosion. It is suggested that the presence of olivine and of highly irregular macrostructure in meteors might indicate the presence of some porosity. For a highly porous meteoroid, it is postulated that during entry into the atmosphere the aerodynamic heat transfer at its external or pore walls would become so intensified as to cause either complete ablation with popping or a solid-liquid-vapor phase transition accompanied by an explosion.

  18. Great Practices

    EPA Pesticide Factsheets

    The National Great Practice Compendium highlights outstanding activities, technologies, and programs that prevent trash from entering the aquatic environment and/or that reduce the overall volume of trash that is generated.

  19. Great Apes

    USGS Publications Warehouse

    Sleeman, Jonathan M.; Cerveny, Shannon

    2014-01-01

    Anesthesia of great apes is often necessary to conduct diagnostic analysis, provide therapeutics, facilitate surgical procedures, and enable transport and translocation for conservation purposes. Due to the stress of remote delivery injection of anesthetic agents, recent studies have focused on oral delivery and/or transmucosal absorption of preanesthetic and anesthetic agents. Maintenance of the airway and provision of oxygen is an important aspect of anesthesia in great ape species. The provision of analgesia is an important aspect of the anesthesia protocol for any procedure involving painful stimuli. Opioids and nonsteroidal anti-inflammatory drugs (NSAIDs) are often administered alone, or in combination to provide multi-modal analgesia. There is increasing conservation management of in situ great ape populations, which has resulted in the development of field anesthesia techniques for free-living great apes for the purposes of translocation, reintroduction into the wild, and clinical interventions.

  20. Frequency synchronization of blue whale calls near Pioneer Seamount.

    PubMed

    Hoffman, Michael D; Garfield, Newell; Bland, Roger W

    2010-07-01

    Vocalizations of blue whales were recorded with a cabled hydrophone array at Pioneer Seamount, 50 miles off the California coast. Most calls occurred in repeated sequences of two-call pairs (A, then B). The B call is a frequency-modulated tone highly repeatable in form and pitch. A model of this sound is described which permits detecting very small frequency shifts. B calls are found to be aligned in frequency to about one part in 180. This requires very fine pitch discrimination and control over calling frequency, and suggests that synchronizing to a common frequency pattern carries some adaptive advantage. Some possibilities for acoustic sensing by whales requiring this fine frequency resolution are discussed.

  1. The magnetisation of Rosemary Bank Seamount, Rockall Trough, northeast Atlantic

    NASA Astrophysics Data System (ADS)

    Miles, P. R.; Roberts, D. G.

    1981-08-01

    Rosemary Bank is a non-uniformly magnetised seamount in the northern Rockall Trough. The reversely magnetised major component of the anomaly field was simulated by a numerical method and modelled using the Talwani three-dimensional magnetics program. The results suggest a higher Koenigsberger ratio than earlier reported for Rosemary Bank and a remanent magnetisation vector compatible with post-Jurassic formation and probably of a Late Cretaceous to Tertiary age. The limited depth to the base of the model implies that Rosemary Bank post-dates the underlying basement in agreement with a volcanic origin. The residual of the observed anomaly field is interpreted as being caused by normally magnetised bodies within and on top of the bank. This suggests subsequent volcanic activity during an interval of normal polarity.

  2. Composition and origin of hydrothermal ironstones from central Pacific seamounts

    USGS Publications Warehouse

    Hein, J.R.; Hsueh-Wen, Y.; Gunn, S.H.; Gibbs, A.E.; Chung-ho, W.

    1994-01-01

    Ironstones recovered from five Late Cretaceous seamounts in the central Pacific region probably formed during late-stage edifice-building volcanism. Ironstones are dense and compact with the appearance of brown chert. The ironstones are characterized by a goethite mineralogy with FeOOH contents up to 88%, extreme fractionation of Fe and Mn, low trace-element and rare earth element abundances, low Co Zn ratios, and isotopic equilibration temperatures of about 20-45 ??C. These characteristics indicate that the ironstones formed from hydrothermal fluids. Ironstones probably formed below the seawater-seafloor interface, as indicated by their occurrence as a proximal hydrothermal deposit, presence of primary goethite cement, pervasive replacement of rocks by goethite, and absence of interbedded pyro-clastic beds. ?? 1994.

  3. Extraordinarily high biomass benthic community on Southern Ocean seamounts.

    PubMed

    Thresher, R E; Adkins, J; Fallon, S J; Gowlett-Holmes, K; Althaus, F; Williams, A

    2011-01-01

    We describe a previously unknown assemblage of seamount-associated megabenthos that has by far the highest peak biomass reported in the deep-sea outside of vent communities. The assemblage was found at depths of 2-2.5 km on rocky geomorphic features off the southeast coast of Australia, in an area near the Sub-Antarctic Zone characterised by high rates of surface productivity and carbon export to the deep-ocean. These conditions, and the taxa in the assemblage, are widely distributed around the Southern mid-latitudes, suggesting the high-biomass assemblage is also likely to be widespread. The role of this assemblage in regional ecosystem and carbon dynamics and its sensitivities to anthropogenic impacts are unknown. The discovery highlights the lack of information on deep-sea biota worldwide and the potential for unanticipated impacts of deep-sea exploitation.

  4. Extraordinarily high biomass benthic community on Southern Ocean seamounts

    PubMed Central

    Thresher, R. E.; Adkins, J.; Fallon, S. J.; Gowlett-Holmes, K.; Althaus, F.; Williams, A.

    2011-01-01

    We describe a previously unknown assemblage of seamount-associated megabenthos that has by far the highest peak biomass reported in the deep-sea outside of vent communities. The assemblage was found at depths of 2–2.5 km on rocky geomorphic features off the southeast coast of Australia, in an area near the Sub-Antarctic Zone characterised by high rates of surface productivity and carbon export to the deep-ocean. These conditions, and the taxa in the assemblage, are widely distributed around the Southern mid-latitudes, suggesting the high-biomass assemblage is also likely to be widespread. The role of this assemblage in regional ecosystem and carbon dynamics and its sensitivities to anthropogenic impacts are unknown. The discovery highlights the lack of information on deep-sea biota worldwide and the potential for unanticipated impacts of deep-sea exploitation. PMID:22355636

  5. 75 FR 17070 - Fisheries in the Western Pacific; Hawaii Bottomfish and Seamount Groundfish Fisheries; Fishery...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... National Oceanic and Atmospheric Administration 50 CFR Part 665 RIN 0648-XU60 Fisheries in the Western Pacific; Hawaii Bottomfish and Seamount Groundfish Fisheries; Fishery Closure AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ]...

  6. 76 FR 10524 - Hawaii Bottomfish and Seamount Groundfish Fisheries; Fishery Closure

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    ... Seamount Groundfish Fisheries; Fishery Closure AGENCY: National Marine Fisheries Service (NMFS), National... closing the commercial and non-commercial fisheries in the main Hawaiian Islands ] fishery for seven... INFORMATION CONTACT: Jarad Makaiau, Sustainable Fisheries Division, NMFS Pacific Islands Region,...

  7. Chemically diverse, sporadic volcanism at seamounts offshore southern and Baja California

    USGS Publications Warehouse

    Davis, A.S.; Gunn, S.H.; Bohrson, W.A.; Gray, L.-B.; Hein, J.R.

    1995-01-01

    Compositions of lavas from seven small to medium-sized seamounts offshore southern and Baja California, include low-K2O tholeiitic, transitional, and mildly to moderately alkalic basalt and their differentiates. The seamounts with these MORB-like lavas are inferred to have formed at or near the spreading center. Based on 40Ar/39Ar laser fusion techniques, MORB-like lava from one of the northern edifices is as old as the underlying oceanic crust (>20 Ma), indicating that it originated at a spreading center. Other seamount lava ages are much younger than the oceanic crust on which they reside. Some of the seamounts with transitional and alkalic lavas may have formed as part of a short, age-progressive chain formed by a short-lived mantle plume. Many others, may have resulted from upwelling mantle diapirs in response to localized extension. -from Authors

  8. Volcanic inflation of Axial Seamount since the 1998 eruption

    NASA Astrophysics Data System (ADS)

    Nooner, S. L.; Chadwick, W.

    2010-12-01

    Since 2000, ambient seawater pressure has been precisely measured at five seafloor benchmarks inside the summit caldera at Axial Seamount in order to measure their relative depth and monitor volcanic inflation that has been occurring since an eruption in 1998. A remotely operated vehicle has been used to deploy a mobile pressure recorder (MPR) in campaign-style surveys, with additional seawater pressure data collected at the caldera center with multiyear deployments of continuously recording bottom pressure recorders (BPRs). Our previous measurements at Axial Seamount have shown steady inflation of the caldera center through 2007 and the spatial pattern of uplift has been consistent with magma storage in a shallow reservoir underlying the caldera at a depth of 3.5 km. This is the only location in the world where long-term monitoring of volcanic inflation has been accomplished at a submarine volcano. Here we present the results of new pressure data (both MPR and BPR) collected during a cruise on board the R/V Thomas Thompson in August-September 2010 and using the Jason ROV. Three years have passed since the previous survey, providing enough time to distinguish between two alternative models of inflation and magma recharge for the volcano. This allows us to refine our forecast for the next eruption at Axial and estimate total uplift that has occurred since the 1998 eruption. During the 2010 survey we also deployed new concrete benchmarks to replace our original galvanized steel benchmarks. The new benchmarks are larger and much heavier, and we expect them to be much more durable and stable over long time periods and help keep measurement errors as small as possible. We installed a sixth benchmark at a new site within the caldera, near the Ashes vent field, which will help constrain our modeling of the inflation signal in future years.

  9. An attempt to explain VLF propagation perturbations associated with single meteors

    NASA Astrophysics Data System (ADS)

    Rault, J.-L.; Delcourt, J.-J.

    2016-01-01

    A first evidence of sudden changes in the amplitude of distant VLF radio transmissions related to single meteors was found during GEM 2010 meteor shower radio observations. Based on many similar observations gathered during different meteor showers, this paper is dedicated to the corresponding physical phenomena involved at the level of the D layer of the Earth ionosphere.

  10. Analysis of molecular nitrogen emisson bands on TV spectrograms of meteors

    NASA Astrophysics Data System (ADS)

    Mukhamednazarov, S.; Amandurdyev, D.; Mal'Tseva, N. V.

    TV spectrograms of three sporadic meteors are compared with photographic spectrograms. It is shown that intense air luminescence is observed in the spectra of fast and relatively faint meteors. It is noted that this luminescence should be taken into account when determining meteor parameters. Emissions of molecular bands and atomic lines of air in the TV spectra are analyzed.

  11. Comets, meteors, and eclipses: Art and science in early Renaissance Italy

    NASA Astrophysics Data System (ADS)

    Olson, R. J. M.; Pasachoff, J. M.

    2002-11-01

    We discuss eight trecento (fourteenth century) paintings containing depictions of astronomical events to reveal the revolutionary advances made in both astronomy and naturalistic painting in early Renaissance Italy, noting that an artistic interest in naturalism predisposed these pioneering painters to make their scientific observations. In turn, the convincing representations of their observations of astronomical phenomena in works of art rendered their paintings more believable, convincing. Padua was already a renowned center for mathematics and nascent astronomy (which was separating from astrology) when Enrico Scrovegni commissioned the famous Florentine artist Giotto di Bondone to decorate his lavish family chapel (circa 1301-1303). Giotto painted a flaming comet in lieu of the traditional Star of Bethlehem in the Adoration of the Magi scene. Moreover, he painted a historical apparition that he recently had observed with a great accuracy even by modern standards. Halley's Comet of 1301 (Olson, 1979). While we do not know the identity of the artist's theological advisor, we discuss the possibility that Pietro d'Abano, the Paduan medical doctor and "astronomer" who wrote on comets, might have been influential. We also compare Giotto's blazing comet with two others painted by the artist's shop in San Francesco at Assisi (before 1316) and account for the differences. In addition, we discuss Giotto's pupil, Taddeo Gaddi, reputed to have been partially blinded by a solar eclipse, whose calamity may find expression in his frescoes in Santa Croce, Florence (1328-30; 1338?). Giotto also influenced the Sienese painter Pietro Lorenzetti, two of whose Passion cycle frescoes at Assisi (1316-20) contain dazzling meteor showers that reveal the artist's observed astronomical phenomena, such as the "radiant" effect of meteor showers, first recorded by Alexander von Humboldt in 1799 and only accepted in the nineteenth century. Lorenzetti also painted sporadic, independent

  12. Geophysical investigation of seamounts near the Ogasawara fracture zone, western Pacific

    USGS Publications Warehouse

    Lee, T.-G.; Lee, Kenneth; Hein, J.R.; Moon, J.-W.

    2009-01-01

    This paper provides an analysis of multi-channel seismic data obtained during 2000-2001 on seamounts near the Ogasawara Fracture Zone (OFZ) northwest of the Marshall Islands in the western Pacific. The OFZ is unique in that it is a wide rift zone that includes many seamounts. Seven units are delineated on the basis of acoustic characteristics and depth: three units (I, II, and III) on the summit of seamounts and four units (IV, V, VI, and VII) in basins. Acoustic characteristics of layers on the summit of guyots and dredged samples indicate that the seamounts had been built above sea level by volcanism. This was followed by reef growth along the summit margin, which enabled deposition of shallow-water carbonates on the summit, and finally by subsidence of the edifices. The subsidence depth of the seamounts, estimated from the lower boundary of unit II, ranges between 1,550 and 2,040 m. The thick unit I of the southern seamounts is correlated with proximity to the equatorial high productivity zone, whereas local currents may have strongly affected the distribution of unit I on northern seamounts. A seismic profile in the basin around the Ita Mai Tai and OSM4 seamounts shows an unconformity between units IV and V, which is widespread from the East Mariana Basin to the Pigafetta Basin. Copyright ?? The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.

  13. Fractures, not Plumes, Have Controlled Major Seamount Volcanism in the Pacific over 170 Million Years

    NASA Astrophysics Data System (ADS)

    Natland, J. H.; Winterer, E. L.

    2003-12-01

    The distribution of guyots and atolls and large volcanic islands on the Pacific plate can be used to outline the likely connection between stresses acting on the plate and the gradual development of large, linear volcanic chains over the past 170 Ma. We construe three general periods with different stress regimes in the history of the Pacific plate. 1) During the Jurassic and Early Cretaceous, the Pacific plate was surrounded by ridge segments and there were no major stress alignments within it. Within-plate volcanism thus assumed the scattered arrangement for the condition of no tectonic stress (1), and the large Magellan and Wake seamount clusters formed. Near the eastern boundaries of the plate, complex and shifting patterns of ridge reorganization dictated formation of very long, splayed, near-axis ridges such as Horizon Guyot and Necker Ridge. 2) At about 90 Ma, the growing middle-aged Pacific plate achieved its first persistent stress regime with the formation of subduction boundaries along its western or northwestern margin. The plate was no longer static but began to move over the asthenosphere and into the mantle. Subduction boundaries and the overall direction of subduction are uncertain, but this imparted a general yet not fully stable component of tension across the plate, producing the NNW Gilbert-Marshall, Line and Emperor Seamount ridges, generally orthogonal to the overall direction of least principal stress. The Line Island seamount chain, being near ridge axes, sustained a variable stress regime. It thus has no age progression of rocks dated between 70-90 Ma (2), great width, and a dual orientations of ridges. 3) By 47 Ma, nearly half of the boundaries of the Pacific plate now were trenches spanning from the Aleutians to New Zealand. In addition, northward migration of the Indian plate and Australia caught a major portion of the westerly moving Pacific plate between the northeast corner of the Tonga Trench and the Aleutians. The plate could not

  14. Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice.

    PubMed

    Gabrielli, Paolo; Barbante, Carlo; Plane, John M C; Varga, Anita; Hong, Sungmin; Cozzi, Giulio; Gaspari, Vania; Planchon, Frédéric A M; Cairns, Warren; Ferrari, Christophe; Crutzen, Paul; Cescon, Paolo; Boutron, Claude F

    2004-12-23

    An iridium anomaly at the Cretaceous/Tertiary boundary layer has been attributed to an extraterrestrial body that struck the Earth some 65 million years ago. It has been suggested that, during this event, the carrier of iridium was probably a micrometre-sized silicate-enclosed aggregate or the nanophase material of the vaporized impactor. But the fate of platinum-group elements (such as iridium) that regularly enter the atmosphere via ablating meteoroids remains largely unknown. Here we report a record of iridium and platinum fluxes on a climatic-cycle timescale, back to 128,000 years ago, from a Greenland ice core. We find that unexpectedly constant fallout of extraterrestrial matter to Greenland occurred during the Holocene, whereas a greatly enhanced input of terrestrial iridium and platinum masked the cosmic flux in the dust-laden atmosphere of the last glacial age. We suggest that nanometre-sized meteoric smoke particles, formed from the recondensation of ablated meteoroids in the atmosphere at altitudes >70 kilometres, are transported into the winter polar vortices by the mesospheric meridional circulation and are preferentially deposited in the polar ice caps. This implies an average global fallout of 14 +/- 5 kilotons per year of meteoric smoke during the Holocene.

  15. Anomalous meteors from the observations with super-isocon TV systems

    NASA Astrophysics Data System (ADS)

    Kozak, P.; Watanabe, J.; Sato, M.

    2014-07-01

    There is a range of both optical and radar observations of meteors the behavior of which essentially differs from the behavior of most meteors. In some cases such meteors cannot be explained in the frame of the classic physical theory of meteors, in other cases the meteors are just of rare type. First of all these are the meteors with true hyperbolic velocities. In spite of the fact that most of hyperbolic orbits are the results of calculation errors, the meteors with extremely high velocities appreciably exceeding the hyperbolic limit of 73 km/s exist and can be of interstellar origin [1--3]. Another very rare phenomenon describes the possible cluster structure of meteor streams, which could be connected with the ejection of the substance from the cometary nucleus shortly before collision of the particles with the Earth [4]. Among anomalies connected with the meteor motion in the atmosphere one can note, first of all, the ultra-high altitudes of meteor beginnings exceeding 130--140 km [5--7]. Some other observations point to the beginning heights of bright meteors from Leonid shower on altitudes near 200 km [8]. The classic physical theory of meteors cannot explain their radiation on such high altitudes because of low air density [9]. Recently the results of TV observations of meteors with diffusive and cloudy structure appeared [9,10]. The results of observations in which, according to author's opinion, the meteors have a few kilometers transverse jets [9--11] were presented as well. There are video frames with bright meteor obtained with high temporal resolution, where authors declared the radiation, which could be an effect of a spread directly of the shock wave [12]. During many years' double-station observations of meteors which have been carrying out at Astronomical Observatory of Kyiv National Taras Shevchenko University the ultra-sensitive TV transmitting tubes of super-isocon type were used [7]. Given type of the tube is one of the most sensitive in the

  16. Sea-surface and deep-magnetic data at Vavilov Seamount, Tyrrhenian Sea

    NASA Astrophysics Data System (ADS)

    Muccini, Filippo; Cocchi, Luca; Locritani, Marina; Carmisciano, Cosmo

    2016-04-01

    Sea surface and deep magnetic data were acquired at Vavilov seamount, in the Tyrrhenian sea. Vavilov seamount is located in the central portion of the homonymous Vavilov basin. The seamount stands about 2800 meters above the seafloor at 3600 meters depth, with the top at about 800 meters below the sea level. Oceanization of the basin occurred during the Late Miocene-Early Pliocene. The magnetic data were collected in 2011 on board the Nave Ammiraglio Magnaghi by using a Marine Magnetics Seaspy magnetometer. The sea surface magnetic survey was realized with two different grids: the first regional one, with 13 parallel lines about 43 Km long, 3 Km spaced (104° N oriented) and 6 tie control lines about 40 Km long, 5 Km spaced (014° N oriented). The second one was realized to better define the volcanic structure of the seamount, and was achieved by acquiring 12 magnetic parallel lines (104° N), 18 Km long and 1 Km spaced. The deep magnetic data were collected by towing a magnetic sensor coupled with a L3 sidescan sonar Klein 3000. A set of 5 parallel lines were acquired in correspondence of the bathymetric top of the seamount with the sensor flying at about constant depth of 700 meters. These data represents the first near-bottom magnetic data collected for Vavilov seamount and it allows comparison between sea-surface and deep magnetic data.

  17. Seafloor deformation and forecasts of the April 2011 eruption at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Chadwick, William W.; Nooner, Scott L.; Butterfield, David A.; Lilley, Marvin D.

    2012-07-01

    Axial Seamount is an active submarine volcano located at the intersection between the Cobb hotspot and the Juan de Fuca spreading centre in the northeast Pacific Ocean. The volcano has been closely monitored since it erupted in 1998 (refs , ). Since then, Axial Seamount seemed to exhibit a similar inflation-deflation cycle to basaltic volcanoes on land and, on that basis, was expected to erupt again sometime before 2014 or 2020 (refs , ). In April 2011 Axial Seamount erupted. Here we report continuous measurements of ocean bottom pressure that document the deflation-inflation cycle of Axial Seamount between 1998 and 2011. We find that the volcano inflation rate, caused by the intrusion of magma, gradually increased in the months leading up to the 2011 eruption. Sudden uplift occurred 40-55min before the eruption onset, which we interpret as a precursor event. Based on our measurements of ground deformation through the entire eruption cycle at Axial Seamount, we suggest that another eruption could occur as early as 2018. We propose that the long-term eruptive cycle of Axial Seamount could be more predictable compared with its subaerial counterparts because the volcano receives a relatively steady supply of magma through the Cobb hotspot and because it is located on thin oceanic crust at a spreading plate boundary.

  18. Isolated communities of Epsilonproteobacteria in hydrothermal vent fluids of the Mariana Arc seamounts.

    PubMed

    Huber, Julie A; Cantin, Holly V; Huse, Susan M; Welch, David B Mark; Sogin, Mitchell L; Butterfield, David A

    2010-09-01

    Low-temperature hydrothermal vent fluids represent access points to diverse microbial communities living in oceanic crust. This study examined the distribution, relative abundance, and diversity of Epsilonproteobacteria in 14 low-temperature vent fluids from five volcanically active seamounts of the Mariana Arc using a 454 tag sequencing approach. Most vent fluids were enriched in cell concentrations compared with background seawater, and quantitative PCR results indicated that all fluids were dominated by bacteria. Operational taxonomic unit-based statistical tools applied to 454 data show that all vents from the northern end of the Mariana Arc grouped together, to the exclusion of southern arc seamounts, which were as distinct from one another as they were from northern seamounts. Statistical analysis also showed a significant relationship between seamount and individual vent groupings, suggesting that community membership may be linked to geographical isolation and not geochemical parameters. However, while there may be large-scale geographic differences, distance is not the distinguishing factor in the microbial community composition. At the local scale, most vents host a distinct population of Epsilonproteobacteria, regardless of seamount location. This suggests that there may be barriers to exchange and dispersal for these vent endemic microorganisms at hydrothermal seamounts of the Mariana Arc.

  19. The prediction of meteor showers from all potential parent comets

    NASA Astrophysics Data System (ADS)

    Neslušan, Luboš; Hajduková, Mária; Tomko, Dušan; Kaňuchová, Zuzana; Jakubík, Marián

    2014-02-01

    The objectives of this project are to predict new meteor showers associated with as many as possible known periodic comets and to find a generic relationship of some already known showers with these comets. For a potential parent comet, we model a theoretical stream at the moment of its perihelion passage in a far past, and follow its dynamical evolution until the present. Subsequently, we analyze the orbital characteristics of the parts of the stream that approach the Earth's orbit. Modelled orbits of the stream particles are compared with the orbits of actual photographic, video, and radar meteors from several catalogues. The whole procedure is repeated for several past perihelion passages of the parent comet. To keep our description compact but detailed, we usually present only either a single or a few parent comets with their associated showers in one paper. Here, an overview of the results from the modelling of the meteor-shower complexes of more than ten parent bodies will be presented. This enables their diversities to be shown. Some parent bodies may associate meteor showers which exhibit a symmetry of their radiant areas with respect to the ecliptic (ecliptical, toroidal, or showers of an ecliptic-toroidal structure), and there are showers which have no counterpart with a similar ecliptical longitude on the opposite hemisphere. However, symmetry of the radiant areas of the pair filaments with respect to the Earth's apex is visible in almost all the complexes which we examined.

  20. The mass and speed dependence of meteor air plasma temperatures

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  1. Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session Asteroids, Meteors, Comets includes the following topics: 1) Where Some Asteroid Parent Bodies; 2) The Collisional Evolution of the Main Belt Population; 3) On Origin of Ecliptic Families of Periodic Comets; 4) Mineralogy and Petrology of Laser Irradiated Carbonaceous Chondrite Mighei; and 5) Interaction of the Gould Belt and the Earth.

  2. Optical meteor fluxes and application to the 2015 Perseids

    NASA Astrophysics Data System (ADS)

    Blaauw, R. C.; Campbell-Brown, M.; Kingery, A.

    2016-11-01

    This paper outlines new methods to measure optical meteor fluxes for showers and sporadic sources. Many past approaches have found the collecting area of a detector at a fixed 100 km altitude, but this approach considers the full volume, finding the area in 2 km height intervals based on the position of the shower or sporadic source radiant and the population's velocity. Here, the stellar limiting magnitude is found every 10 min during clear periods and converted to a limiting meteor magnitude for the shower or sporadic source having fluxes measured, which is then converted to a limiting mass. The final output is a mass-limited flux for meteor showers or sporadic sources. Presented are the results of these flux methods as applied to the 2015 Perseid meteor shower as seen by the Meteoroid Environment Office's eight wide-field cameras. The peak Perseid flux on the night of 2015 August 13 was measured to be 0.002989 meteoroids/km2/hr down to 0.00051 g, corresponding to a ZHR of 100.7.

  3. A (revised) confidence index for the forecasting of meteor showers

    NASA Astrophysics Data System (ADS)

    Vaubaillon, J.

    2016-01-01

    A confidence index for the forecasting of meteor showers is presented. The goal is to provide users with information regarding the way the forecasting is performed, so several degrees of confidence is achieved. This paper presents the meaning of the index coding system.

  4. Limitations of the current methods used to compute meteors orbits

    NASA Astrophysics Data System (ADS)

    Egal, A.; Gural, P.; Vaubaillon, J.; Colas, F.; Thuillot, W.

    2015-10-01

    The Cameras for BEtter Resolution NETwork (CABERNET) project aims to provide the most accurate meteoroid orbits achievable working with digital recordings of night sky imagery. The level of performance obtained is governed by the technical attributes of the collection systems and having both accurate and robust data processing. The technical challenges have been met by employing three cameras, each with a field of view of 40°x26° and a spatial (angular) resolution of 0.01°/pixel. The single image snapshots of meteors achieve temporal discrimination along the track through the use of an electronic shutter coupled to the cameras, operating at a sample rate between 100Hz and 200Hz. The numerical processing of meteor trajectories has already been explored by many authors. This included an examination of the intersecting planes method developed by Ceplecha (1987), the least squares method of Borovicka (1990), and the multi-fit parameterization method published by Gural (2012). After a comparison of these three techniques, we chose to implement Gural 's method, employing several non-linear minimization techniques and trying to match the modeling as close as possible to the basic data measured, i.e. the meteor space-time positions in the sequence of images. This approach results in a more precise and reliable way to determine both the meteor trajectory and velocity through the atmosphere.

  5. SPA Meteor Section Results: January-March 2004

    NASA Astrophysics Data System (ADS)

    McBeath, Alastair

    2007-06-01

    Details from analyzed reports submitted to the SPA Meteor Section for the first quarter of 2004 are presented and discussed, with notes on some other events drawn to the Section's attention. A Quadrantid maximum in visual and radio results at about 04h UT on January 4 can be implied, perhaps with visual ZHRs of order 150-230, though moonlight made this value less reliable than the ideal. Some details are given on a meteoritic daylight fireball over northern Spain on January 4 at 16h46m UT, and another fireball over Belgium-Germany on January 21, at app. 05h33m UT. A mysterious `meteor storm' sighting from February 19/20 was almost certainly not meteoric, but the first observation of a meteor in the atmosphere of Mars from March 7, probably was. One more widely-seen fireball, this time for the UK, occurred around 22h03m UT on March 25/26, for which an approximate surface track could be established. An obituary for the author's father Peter McBeath (1923-2004), who died at the end of March, completes the article.

  6. Improving Photometric Calibration of Meteor Video Camera Systems

    NASA Technical Reports Server (NTRS)

    Ehlert, Steven; Kingery, Aaron; Suggs, Robert

    2016-01-01

    We present the results of new calibration tests performed by the NASA Meteoroid Environment Oce (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the rst point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric ux within the camera band-pass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at 0:20 mag, and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to 0:05 ?? 0:10 mag in both ltered and un ltered camera observations with no evidence for lingering systematics.

  7. Radar meteor orbital structure of Southern Hemisphere cometary dust streams

    NASA Technical Reports Server (NTRS)

    Baggaley, W. Jack; Taylor, Andrew D.

    1992-01-01

    The Christchurch, New Zealand meteor orbit radar (AMOR) with its high precision and sensitivity, permits studies of the orbital fine structure of cometary streams. PC generated graphics are presented of data on some Southern Hemisphere Streams. Such data can be related to the formation phase and subsequent dynamical processes of dust streams.

  8. Assessing risk from dangerous meteoroids in main meteor showers

    NASA Astrophysics Data System (ADS)

    Murtazov, A.

    2015-01-01

    The risk from dangerous meteoroids in main meteor showers is calculated. The showers were: Quadrantids-2014; Eta Aquariids-2013, Perseids-2014 and Geminids-2014. The computed results for the risks during the shower periods of activity and near the maximum are provided.

  9. CAMS newly detected meteor showers and the sporadic background

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.; Nénon, Q.; Gural, P. S.; Albers, J.; Haberman, B.; Johnson, B.; Morales, R.; Grigsby, B. J.; Samuels, D.; Johannink, C.

    2016-03-01

    The Cameras for Allsky Meteor Surveillance (CAMS) video-based meteoroid orbit survey adds 60 newly identified showers to the IAU Working List of Meteor Showers (numbers 427, 445-446, 506-507, and part of 643-750). 28 of these are also detected in the independent SonotaCo survey. In total, 230 meteor showers and shower components are identified in CAMS data, 177 of which are detected in at least two independent surveys. From the power-law size frequency distribution of detected showers, we extrapolate that 36% of all CAMS-observed meteors originated from ∼700 showers above the N = 1 per 110,000 shower limit. 71% of mass falling to Earth from streams arrives on Jupiter-family type orbits. The transient Geminids account for another 15%. All meteoroids not assigned to streams form a sporadic background with highest detected numbers from the apex source, but with 98% of mass falling in from the antihelion source. Even at large ∼7-mm sizes, a Poynting-Robertson drag evolved population is detected, which implies that the Grün et al. collisional lifetimes at these sizes are underestimated by about a factor of 10. While these large grains survive collisions, many fade on a 104-y timescale, possibly because they disintegrate into smaller particles by processes other than collisions, leaving a more resilient population to evolve.

  10. Asteroids, comets, meteors, and their interrelations. Part II: Editorial review

    NASA Astrophysics Data System (ADS)

    Muinonen, Karri; Granvik, Mikael; Penttilä, Antti; Gritsevich, Maria

    2016-04-01

    The Asteroids, Comets, Meteors 2014 (ACM 2014) conference was organized in Helsinki in June 30-July 4, 2014, with the first collection of the peer-reviewed papers published in December 2015 in the Special Issue of Planetary and Space Science (Muinonen et al., 2015). The present issue contains the second collection of papers from ACM 2014.

  11. Nuclear test monitoring system detected meteor explosion over Russia

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-10-01

    Sound waves from the Chelyabinsk meteor, which exploded over Russia on 15 February 2013, were detected by 20 infrasound stations that are part of the international monitoring system operated by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The fireball was the most energetic event observed since the 1908 Tunguska meteorite impact and is the most energetic event detected by the CTBTO network.

  12. Dispersion of meteor trails in the geomagnetic field.

    PubMed

    Robson, R E

    2001-02-01

    A meteor trail is modeled by a long column of weakly ionized plasma, whose dispersion is controlled by the geomagnetic field and the requirement to maintain effective space charge neutrality. First we consider scattering of a radar signal from an underdense trail and derive an expression for the amplitude of the backscattered signal as a function of time. Then, starting from the basic momentum balance equations for electrons and ions in a partially ionized plasma, we require divergences of ion and electron fluxes to be equal, plus assume equality of the flux components along the magnetic field direction. The analysis is really applicable to a whole range of plasma problems, although we focus upon meteor trails for now. It is found that charged particle densities satisfy a diffusion equation and we obtain an expression for the ambipolar diffusion tensor and expressions for the ambipolar electric field, valid for arbitrary relative orientations of the magnetic field and meteor trail axis. Results are somewhat different from previous analyses in the meteor literature.

  13. The mass and speed dependence of meteor air plasma temperatures.

    PubMed

    Jenniskens, Peter; Laux, Christophe O; Wilson, Michael A; Schaller, Emily L

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  14. Leonid meteor ablation, energy exchange and trail morphology

    SciTech Connect

    Zinn, John; Judd, O'Dean P.; ReVelle, D. O.

    2002-01-01

    This paper describes theoretical model studies of the interaction of Leonid meteoroids with the earth's atmosphere. Subject to some modest-to-strenuous approximations we compute the rates of ablation and deceleration, energy deposition, and terminal altitudes of the meteors as functions of their initial mass and bulk density, velocity, trajectory entry angle, drag coefficient, heat of ablation, and an ablation energy transfer fraction. We find that the dominant energy deposition in the atmosphere is associated with the stopping of the ablated meteor particles and vapor by the surrounding air. Then having computed the energy deposition rates versus altitude we compute the hydrodynamic and radiative expansion of the hot wake material in the radial direction, along with the associated air chemistry. From the computed results we can then plot two-dimensional temperature contours -- as functions of the instantaneous distance behind the meteor and radial distance from the center of the wake, at various altitudes along the meteor's path. We also compute the rates of emission of radiation and the radiative efficiency, and discuss comparisons with observations.

  15. The 2017 Meteor Shower Activity Forecast for Earth Orbit

    NASA Technical Reports Server (NTRS)

    Moorehead, Althea; Cooke, Bill; Moser, Danielle

    2017-01-01

    Most meteor showers will display typical activity levels in 2017. Perseid activity is expected to be higher than normal but less than in 2016; rates may reach 80% of the peak ZHR in 2016. Despite this enhancement, the Perseids rank 4th in flux for 0.04-cm-equivalent meteoroids: the Geminids (GEM), Daytime Arietids (ARI), and Southern delta Aquariids (SDA) all produce higher fluxes. Aside from heightened Perseid activity, the 2017 forecast includes a number of changes. In 2016, the Meteoroid Environment Office used 14 years of shower flux data to revisit the activity profiles of meteor showers included in the annual forecast. Both the list of showers and the shape of certain major showers have been revised. The names and three-letter shower codes were updated to match those in the International Astronomical Union (IAU) Meteor Data Center, and a number of defunct or insignificant showers were removed. The most significant of these changes are the increased durations of the Daytime Arietid (ARI) and Geminid (GEM) meteor showers. This document is designed to supplement spacecraft risk assessments that incorporate an annual averaged meteor shower flux (as is the case with all NASA meteor models). Results are presented relative to this baseline and are weighted to a constant kinetic energy. Two showers - the Daytime Arietids (ARI) and the Geminids (GEM) - attain flux levels approaching that of the baseline meteoroid environment for 0.1-cm-equivalent meteoroids. This size is the threshold for structural damage. These two showers, along with the Quadrantids (QUA) and Perseids (PER), exceed the baseline flux for 0.3-cm-equivalent particles, which is near the limit for pressure vessel penetration. Please note, however, that meteor shower fluxes drop dramatically with increasing particle size. As an example, the Arietids contribute a flux of about 5x10(exp -6) meteoroids m(exp -2) hr-1 in the 0.04-cm-equivalent range, but only 1x10(exp -8) meteoroids m(sub -2) hr-1 for the 0

  16. Devolatilization or melting of carbonates at Meteor Crater, AZ?

    NASA Astrophysics Data System (ADS)

    Hörz, F.; Archer, P. D.; Niles, P. B.; Zolensky, M. E.; Evans, M.

    2015-06-01

    We have investigated the carbonates in the impact melts and in a monolithic clast of highly shocked Coconino sandstone of Meteor Crater, AZ to evaluate whether melting or devolatilization is the dominant response of carbonates during high-speed meteorite impact. Both melt- and clast-carbonates are calcites that have identical crystal habits and that contain anomalously high SiO2 and Al2O3. Also, both calcite occurrences lack any meteoritic contamination, such as Fe or Ni, which is otherwise abundantly observed in all other impact melts and their crystallization products at Meteor Crater. The carbon and oxygen isotope systematics for both calcite deposits suggest a low temperature environment (<100 °C) for their precipitation from an aqueous solution, consistent with caliche. We furthermore subjected bulk melt beads to thermogravimetric analysis and monitored the evolving volatiles with a quadrupole mass spectrometer. CO2 yields were <5 wt%, with typical values in the 2 wt% range; also total CO2 loss is positively correlated with H2O loss, an indication that most of these volatiles derive from the secondary calcite. Also, transparent glasses, considered the most pristine impact melts, yield 100 wt% element totals by EMPA, suggesting complete loss of CO2. The target dolomite decomposed into MgO, CaO, and CO2; the CO2 escaped and the CaO and MgO combined with SiO2 from coexisting quartz and FeO from the impactor to produce the dominant impact melt at Meteor Crater. Although confined to Meteor Crater, these findings are in stark contrast to Osinski et al. (2008) who proposed that melting of carbonates, rather than devolatilization, is the dominant process during hypervelocity impact into carbonate-bearing targets, including Meteor Crater.

  17. Towards a global model of the meteoric metal layers

    NASA Astrophysics Data System (ADS)

    Plane, John; Feng, Wuhu; Marsh, Daniel; Janches, Diego; Chipperfield, Martyn; Burrows, John P.; Sinnhuber, Miriam

    This paper will describe a major new initiative to develop a global model of the Na, Fe, Ca and Mg layers which are produced in the upper mesosphere and lower thermosphere by mete-oric ablation. The 4M (Multi-scale Modelling of Mesospheric Metals) project brings together three components: the injection of meteoric constituents into the atmosphere; the neutral and ion-molecule chemistries of these four metals; and a general circulation model of the whole atmosphere. The injection rates are calculated by combining the meteoric input function (MIF), an astro-nomical model which determines the meteoric size distribution and infall velocity distribution as a function of location and time, and a chemical ablation model (CABMOD), which calcu-lates the ablation rates of the different meteoric elements for a meteoroid of specified mass and velocity. The atmospheric chemistries of Na, Fe, Ca and Mg are now quite well understood: the kinetics of most of their important atmospheric reactions have been studied in the laboratory under appropriate conditions. This has enabled 1-dimensional models of these metallic layers to be produced, which compare satisfactorily with observations by ground-based lidar and space-borne spectrometers. The global model which has been chosen for the 4M project is the Whole Atmosphere Chemistry Climate Model (WACCM), developed at NCAR (Boulder). The model extends from 0 -140 km and includes a full treatment of neutral chemistry and lower E region ion chemistry. We will present the initial results on modelling the global Na and Fe layers.

  18. Implications from Meteoric and Volcanic Infrasound Measured in the Netherlands

    NASA Astrophysics Data System (ADS)

    Evers, L.

    2003-12-01

    Infrasound observations started in the Netherlands in 1986. Since then, several array configurations and instruments have been developed, tested and made operational. Currently, three infrasound arrays are continuously measuring infrasound with in-house developed microbarometers. The array apertures vary from 30 to 1500 meters and the number of instruments from 6 to 16 microbarometers. The inter-array distance ranges from 50 up to 150 km. This dense network of infrasound arrays is used to distinguish between earthquakes and sources in the atmosphere. Sonic booms, for example, can be experienced in the same manner as small (gas induced) earthquakes. Furthermore, Comprehensive Nuclear-Test-Ban Treaty (CTBT) related research is done. Meteors are one of the few natural impulsive sources generating energy in kT TNT equivalent range. Therefore, the study of meteors is essential to the CTBT where infrasound is applied as monitoring technique. Studies of meteors in the Netherlands have shown the capability of infrasound to trace a meteor through the stratosphere. The propagation of infrasound is in first order dependent on the wind and temperature structure of the atmosphere. The meteor's path could be reconstructed by using ECMWF atmospheric models for wind and temperature. The results were compared to visual observations, confirming the location, direction and reported origin time. The accuracy of the localization mainly depends on the applied atmospheric model and array resolution. Successfully applying infrasound depends on the array configuration that should be based on the -frequency depend- spatial coherence of the signals of interest. The array aperture and inter-element distance will play a decisive role in detecting low signal-to-noise ratios. This is shown by results from studies on volcanic infrasound from Mt. Etna (Italy) detected in the Netherlands. Sub-array processing on the 16 element array revealed an increased detectability of infrasound for small

  19. Open-source meteor detection software for low-cost single-board computers

    NASA Astrophysics Data System (ADS)

    Vida, D.; Zubović, D.; Šegon, D.; Gural, P.; Cupec, R.

    2016-01-01

    This work aims to overcome the current price threshold of meteor stations which can sometimes deter meteor enthusiasts from owning one. In recent years small card-sized computers became widely available and are used for numerous applications. To utilize such computers for meteor work, software which can run on them is needed. In this paper we present a detailed description of newly-developed open-source software for fireball and meteor detection optimized for running on low-cost single board computers. Furthermore, an update on the development of automated open-source software which will handle video capture, fireball and meteor detection, astrometry and photometry is given.

  20. Anomalous photometrical displays in faint meteors from TV observations in Kyiv

    NASA Astrophysics Data System (ADS)

    Kozak, P. M.

    2016-10-01

    Analysis of a large range of results of modern TV meteor observations for searching presence their of the meteors with highly displayed anomalies in kinematic and photometrical characteristics has been carried out. In parallel, the results of Kyiv meteor group observations obtained with the help of observational systems equipped by high sensitive transmitting TV tubes of superisocon type, which have a range of highly displayed anomalies in a meteor development are presented. Comparative qualitative analysis of the observational data containing anomalous displays in meteor photometrical parameters, in part in their light curves is carried out, and the conclusions about physical reality of technical artifacts of the selected anomalies are done.

  1. Great Comets

    NASA Astrophysics Data System (ADS)

    Burnham, Robert

    2000-05-01

    Spectacular and mysterious objects that come and go in the night sky, comets have dwelt in our popular culture for untold ages. As remnants from the formation of the Solar system, they are objects of key scientific research and space missions. As one of nature's most potent and dramatic dangers, they pose a threat to our safety--and yet they were the origin of our oceans and perhaps even life itself. This beautifully illustrated book tells the story of the biggest and most awe-inspiring of all comets: those that have earned the title "Great." Robert Burnham focuses on the Great comets Hyakutake in 1996 and Hale-Bopp in 1997, which gripped attention worldwide because, for many, they were the first comets ever seen. He places these two recent comets in the context of their predecessors from past ages, among them the famous Comet Halley. Great Comets explains the exciting new discoveries that have come from these magnificent objects and profiles the spaceprobes to comets due for launch in the next few years. The book even takes a peek behind Hollywood's science-fiction fantasies to assess the real risks humanity faces from potential impacts of both comets and asteroids. For everyone interested in astronomy, this exciting book reveals the secrets of the Great Comets and provides essential tools for keeping up to date with comet discoveries in the future. Robert Burnham has been an amateur astronomer since the mid-1950s. He has been a senior editor of Astronomy magazine (1986-88) and is the author of many books and CD-ROMS, including Comet Hale-Bopp: Find and Enjoy the Great Comet and Comet Explorer.

  2. Meiofauna assemblages of the Condor Seamount (North-East Atlantic Ocean) and adjacent deep-sea sediments

    NASA Astrophysics Data System (ADS)

    Zeppilli, Daniela; Bongiorni, Lucia; Cattaneo, Antonio; Danovaro, Roberto; Santos, Ricardo Serrão

    2013-12-01

    Seamounts are currently considered hotspots of biodiversity and biomass for macro- and megabenthic taxa, but knowledge of meiofauna is still limited. Studies have revealed the existence of highly diverse meiofauna assemblages; however most data are mainly qualitative or focused only on specific groups, thus preventing comparisons among seamounts and with other deep-sea areas. This study, conducted on Condor Seamount (Azores, North-East Atlantic Ocean), describes variation in abundance, biomass, community structure and biodiversity of benthic meiofauna from five sites located on the Condor Seamount: and one site away from the seamount. While the summit of the seamount hosted the highest alpha biodiversity, the flanks and the bases showed a rich meiofauna assemblage in terms of abundance and biomass. The observed marked differences in grain size composition of sediments reflected the oceanographic conditions impacting different sectors of the Condor seamount, and could play an important role in the spatial distribution of different meiofaunal taxa. Trophic conditions (biochemical composition of organic matter) explained 78% of the variability in the meiofauna biomass pattern while sediment grain influenced the vertical distribution of meiofauna and only partially explained meiofaunal taxa composition. This study provides a further advancement in the knowledge of meiofaunal communities of seamounts. Only a deeper understanding of the whole benthic communities (including meiofauna) will allow to elaborate effective management and conservation tools for seamount ecosystems.

  3. A synthetical index of the potential threats about intense activities of meteors

    NASA Astrophysics Data System (ADS)

    Wu, Guang-jie

    2006-10-01

    In the present age, several techniques for the application to the observation of meteors and meteor showers have been developed in modern meteor astronomy. The initial definition for a meteor storm based on the visual observation with a Zenithal Hourly Rate of above 1000 seems insufficient now, since it only means a storm or burst of meteors in numbers and means that an eyewitness could have a chance to see a spectacular meteor show. Up to now, peoples have also recorded the meteoric flashes on the Moon during the Leonid meteor showers. Especially, the increasing activities of mankind in space for scientific, commercial and military purposes, have led to an increase in the problems concerning the safety of the satellites, space stations and astronauts. How the intense activity of a meteor storm is defined and forecast, some new points of view are needed. In this paper, several aspects about the intensity of the meteor storm are analyzed, including the number, mass, impulse, energy, electric charge, different purposes and different physical meanings. Finally, a synthetical index denoting the activity and potential threat of an intense meteor shower is suggested.

  4. Variations of Magnitude and Ionization Along the Traces of the Same Meteors

    NASA Astrophysics Data System (ADS)

    Narziev, Mirhusen

    2016-07-01

    Using the results of simultaneous television and basic radar observations of meteors from points 4-5, received during the periods of activity of the main annual meteor showers α - Kaprikornis, δ - Akvarids, Geminids, Quadrantids and Orionids in 1979 in GisAO, the variation of magnitude and linear electronic density along a traces of the same meteors were studied. It was determined that for meteors with velocities of 23-69 km/c the course of variation of magnitude and linear electronic density along the traces of the same meteors were fairly coordinated among themselves. The received results are compared with the similar data received for weaker meteors in Harward (Illinois). It is concluded that the difference between radar-tracking and photographic magnitude depends on the speed of meteors.

  5. Video and photometric observations of a sprite in coincidence with a meteor-triggered jet event

    SciTech Connect

    Suszcynsky, D. M.; Strabley, R.; Roussel-Dupre, R.; Symbalisty, E. M. D.; Armstrong, R. A.; Lyons, W. A.; Taylor, M.

    1999-12-27

    Video and photometric observations of a meteor-triggered ''jet'' event in association with the occurrence of a sprite were collected during the SPRITES '98 campaign. The event raises interest in the question of possible meteoric triggering of upper atmospheric transients as originally suggested by Muller [1995]. The event consisted of three stages: (1) the observation of a moderately bright meteor, (2) the development of a sprite in the immediate vicinity of the meteor as the meteor reached no lower than {approx}70 km altitude, and (3) a slower-forming jet of luminosity that appeared during the late stages of the sprite and propagated back up the ionization trail of the meteor. The event is analyzed in terms of its geometry, its relevance to the meteor, and the implications to existing theories for sprite formation. (c) 1999 American Geophysical Union.

  6. Petrological variability in recent magmatism at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Dreyer, B. M.; Clague, D. A.; Gill, J. B.

    2011-12-01

    Axial Seamount is known for its compositional homogeneity. We report on petrological variability in lavas from the summit caldera and rims of Axial Seamount during the last ~1.2ka and its implications for shallow crustal magma dynamics. AUVs have mapped the summit at ~1 m resolution, and ROVs have collected numerous lavas and volcaniclastic cores. Geospatial, superpositional, compositional, and age constraint data were used to outline flow units and construct geologic maps. Nearly 200 glasses from summit lavas were analyzed for major elements. A subset of ~20 samples were analyzed for selected trace elements, Pb-, U-, and Th- isotope ratios, and 226Ra and 210Pb. The results a) confirm a high degree compositional homogeneity, b) demonstrate a more restricted range in Pb-isotope ratios than previous data, c) indicate uniform compositional source component(s) genetically linked to that of the Cobb-Eickelberg seamount chain, and d) expand the dataset of distinctly-low 230Th/232Th lavas and subdivide them into geospatial groups. Hundreds of volcaniclastic grains collected from subsurface depths of up to several tens of cm analyzed for major elements extend the record of summit magmatism beyond what is exposed. Summit lava glasses are compositionally N-MORB. Summit volcaniclastics range to higher MgO (+1%); thus, magmatism likely included more mafic episodes than is recorded in the flows as yet sampled or that volcaniclastics preferentially sample higher temperature lavas. Negative correlation of CaO/Al2O3 with MgO in all glasses suggests fractionation from parental melt(s) of plag ± ol but not cpx. K2O/TiO2 ranges are typical for much of the JdFR. Summit lavas range from aphyric to ~35% plag phyric ± a few % ol. Plag-phyric summit lavas tend to have greater MgO (>7.5%), lower CaO/Al2O3 (<0.80), and lower K2O/TiO2 (<0.10) compared to aphyric lavas. For ~18 caldera flows with absolute or relative age control, plag-phyric lavas are older than aphyric lavas, the oldest of

  7. Great Expectations for "Great Expectations."

    ERIC Educational Resources Information Center

    Ridley, Cheryl

    Designed to make the study of Dickens'"Great Expectations" an appealing and worthwhile experience, this paper presents a unit of study intended to help students gain (1) an appreciation of Dickens' skill at creating realistic human characters; (2) an insight into the problems of a young man confused by false values and unreal ambitions…

  8. Impulsive Seafloor Signals from the 2015 Eruption of Axial Seamount

    NASA Astrophysics Data System (ADS)

    Garcia, C.; Wilcock, W. S. D.; Tan, Y. J.; Tolstoy, M.

    2015-12-01

    Axial Seamount is a hotspot volcano on the Juan de Fuca Ridge that has erupted three times over the past two decades. The most recent eruption was recorded by a cabled seismic network in the southern half of the summit caldera that has been operated by the Ocean Observatories Initiative (OOI) since November 2014. After five months of increasing seismicity, a 10-hour seismic crisis involving thousands of earthquakes began at 0500 GMT on April 24, 2015 accompanied by ~2 m of deflation in the central caldera (Nooner et al., this meeting). Local seismicity declined rapidly after the eruption, but thousands of impulsive waterborne events were observed across the network starting immediately after the seismic crisis. Over 1500 events per day were recorded on April 25 and 26, decreasing to less than 500 per day after May 1, and ceasing altogether around May 20. Each event comprises a train of three to five consistently spaced arrivals visible on all 3 seismometer channels with a broad frequency content of 10-100 Hz. The timing of arrivals across the network is consistent with water column multiples from a seafloor source to the north. A subset of events has been manually picked and located by modeling travel times of the first three arrivals assuming flat bathymetry at a range of depths between 1500-1800 m and a sound speed of 1.5 km/s. The preliminary locations are clustered around Axial Seamount's northern rift at a distance of 10-15 km from the north rim of the caldera. In July, an OOI cruise discovered fresh pillow lavas up to 100 m thick and 670 m wide, and extending for 7 km along the rift in the same region (Kelley et al., this meeting). The source of the impulsive events is uncertain and could involve gas explosions, bubble collapse, and thermal or mechanical cracking, but their colocation with the fresh lava flow suggests that ocean bottom seismic networks can not only track the faulting and fracturing associated with subsurface magma movements but also the

  9. Near-ridge seamount chains in the northeastern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Clague, David A.; Reynolds, Jennifer R.; Davis, Alicé S.

    2000-07-01

    High-resolution bathymetry and side-scan data of the Vance, President Jackson, and Taney near-ridge seamount chains in the northeast Pacific were collected with a hull-mounted 30-kHz sonar. The central volcanoes in each chain consist of truncated cone-shaped volcanoes with steep sides and nearly flat tops. Several areas are characterized by frequent small eruptions that result in disorganized volcanic regions with numerous small cones and volcanic ridges but no organized truncated conical structure. Several volcanoes are crosscut by ridge-parallel faults, showing that they formed within 30-40 km of the ridge axis where ridge-parallel faulting is still active. Magmas that built the volcanoes were probably transported through the crust along active ridge-parallel faults. The volcanoes range in volume from 11 to 187 km3, and most have one or more multiple craters and calderas that modify their summits and flanks. The craters (<1 km diameter) and calderas (>1 km diameter) range from small pit craters to calderas as large as 6.5×8.5 km, although most are 2-4 km across. Crosscutting relationships commonly show a sequence of calderas stepping toward the ridge axis. The calderas overlie crustal magma chambers at least as large as those that underlie Kilauea and Mauna Loa Volcanoes in Hawaii, perhaps 4-5 km in diameter and ˜1-3 km below the surface. The nearly flat tops of many of the volcanoes have remnants of centrally located summit shields, suggesting that their flat tops did not form from eruptions along circumferential ring faults but instead form by filling and overflowing of earlier large calderas. The lavas retain their primitive character by residing in such chambers for only short time periods prior to eruption. Stored magmas are withdrawn, probably as dikes intruded into the adjacent ocean crust along active ridge-parallel faults, triggering caldera collapse, or solidified before the next batch of magma is intruded into the volcano, probably 1000-10,000 years

  10. Seasonal changes in fish assemblage structure at a shallow seamount in the Gulf of California

    PubMed Central

    Klimley, A. Peter; Muhlia-Melo, Arturo; Morgan, Steven G.

    2016-01-01

    Seamounts have generally been identified as locations that can promote elevated productivity, biomass and predator biodiversity. These properties attract seamount-associated fisheries where elevated harvests can be obtained relative to surrounding areas. There exists large variation in the geological and oceanographic environment among the thousands of locations that fall within the broad definition of seamount. Global seamount surveys have revealed that not all seamounts are hotspots of biodiversity, and there remains a strong need to understand the mechanisms that underlie variation in species richness observed. We examined the process of fish species assembly at El Bajo Espiritu Santo (EBES) seamount in the Gulf of California over a five-year study period. To effectively quantify the relative abundance of fast-moving and schooling fishes in a ‘blue water’ habitat, we developed a simplified underwater visual census (UVC) methodology and analysis framework suitable for this setting and applicable to future studies in similar environments. We found correlations between seasonally changing community structure and variability in oceanographic conditions. Individual species responses to thermal habitat at EBES revealed three distinct assemblages, a ‘fall assemblage’ tracking warmer overall temperature, a ‘spring assemblage’ correlated with cooler temperature, and a ‘year-round assemblage’ with no significant response to temperature. Species richness was greatest in spring, when cool and warm water masses stratified the water column and a greater number of species from all three assemblages co-occurred. We discuss our findings in the context of potential mechanisms that could account for predator biodiversity at shallow seamounts. PMID:27651985

  11. Distribution of zooplankton biomass at three seamounts in the NE Atlantic

    NASA Astrophysics Data System (ADS)

    Martin, Bettina; Christiansen, Bernd

    2009-12-01

    During different seasons of the years 2003-2005 in the NE Atlantic, zooplankton were sampled with a MOCNESS (multiple opening/closing net and environmental sensing system, mesh size 333 μm) above the slopes and summits of Seine, Sedlo and Ampère seamounts and at remote reference sites outside the influence of the seamounts (far field). Wet weights of different zooplankton size classes (<0.5, 0.5-2, >2 cm) were measured. Night and day hauls were analysed in order to detect diel vertical migrations of the zooplankton, as well as a possible trapping effect due to the shallow topography. Biomass concentrations, independent of daytime, season and summit height, were reduced above the summits at all three seamounts compared to the slope and far-field sites. No trapping effect or retention of biomass was apparent above the seamounts. The vertical distribution patterns of the size class <0.5 cm did not differ between night and day hauls at most sites, but indications of diel vertical migrations were found in the larger size fractions. With the exception of gelatinous organisms, zooplankton >0.5 cm were nearly absent above the summits of Seine and Ampère seamounts, but considerable numbers were found above the slopes and at the far-field sites. Possible explanations for the observed distribution patterns of zooplankton biomass and size classes are discussed, including retention and lateral advection due to the hydrography at the seamounts, as well as predation by resident seamount fish.

  12. The MAGIC Meteoric Smoke Particle Sampler - Description and Results

    NASA Astrophysics Data System (ADS)

    Hedin, J.

    2013-12-01

    Between a few to several hundred tons of meteoric material enters the Earth's atmosphere each day, and much of this material ablates in the 70 -130 km region of the atmosphere. Already in the early 1960's it was suggested that meteoroid ablation products could recondense and form solid nanometer-scale smoke particles in the altitude range of the mesosphere and lower thermosphere (MLT). These so-called meteoric smoke particles (MSPs) are then subject to further coagulation, sedimentation, and transport by the mesospheric meridional circulation which in turn determines the latitudinal and seasonal variation of the MSP distribution. MSPs have been suggested to be important for a variety of atmospheric phenomena: 1. they are the most likely candidate for the nuclei of mesospheric ice particles (NLC and PMSE); 2. they provide surface area on which heterogeneous chemical reactions take place and may influence, for example, the water vapor distribution and Ox/HOx chemistry in the mesosphere; 3. they act as ultimate sink in mesospheric metal chemistry by scavenging various gas-phase products of meteoric ablation; 4. they can significantly influence the ionospheric D-region charge balance by scavenging free electrons and positive ions; and 5. they may be involved in the formation of NAT particles in polar stratospheric clouds and the destruction of ozone. Given the above points, it is obvious that there is a large scientific interest in the properties and global distribution of MSPs. Basic information about MSP properties is today available from optical occultation measurements (AIM/SOFIE) and, more indirectly, from in-situ measurements of the charged particle population. In order to understand the role of meteoric smoke particles in the mesosphere and their impact on that environment their presence must be certified and their physical characterization (number density, size distribution, shape, composition etc.) determined. A way to obtain maximum information about particle

  13. Dynamical Model for the Zodiacal Cloud and Sporadic Meteors

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Janches, Diego; Vokrouhlický, David; Pokorný, Petr; Bottke, William F.; Jenniskens, Peter

    2011-12-01

    The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving at the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (gsim 105 yr at 1 AU) than postulated in the standard collisional models (~104 yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) × 1011 km2 and ~4 × 1019 g, respectively, in a good agreement with previous studies. The mass input required to keep the zodiacal cloud in a steady state is estimated to be ~104-105 kg s-1. The input is up to ~10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 μm and 1 cm is found to be ~15,000 tons yr-1 (factor of two uncertainty), which is a large share of the accretion flux measured by the Long Term Duration

  14. Dynamical Model for the Zodiacal Cloud and Sporadic Meteors

    NASA Technical Reports Server (NTRS)

    Nesvorny, David; Janches, Diego; Vokrouhlicky, David; Pokorny, Petr; Bottke, William F.; Jenniskens, Peter

    2011-01-01

    The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving to the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (approx. > 10(exp 5) yr at 1 AU) than postulated in the standard collisional models (approx 10(exp 4) yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite (IRAS) to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) 10(exp 11) sq km and approx. 4 10(exp 19) g, respectively, in a good agreement with previous studies. The mass input required to keep the Zodiacal Cloud (ZC) in a steady state is estimated to be approx. 10(exp 4)-10(exp 5) kg/s. The input is up to approx 10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes, and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 micron and 1 cm is found to be approx 15,000 tons/yr (factor of 2 uncertainty), which is

  15. Morphometry of Concepcion Bank: Evidence of Geological and Biological Processes on a Large Volcanic Seamount of the Canary Islands Seamount Province.

    PubMed

    Rivera, Jesus; Canals, Miquel; Lastras, Galderic; Hermida, Nuria; Amblas, David; Arrese, Beatriz; Martín-Sosa, Pablo; Acosta, Juan

    2016-01-01

    Concepcion Bank is the largest seamount in the Canary Islands Seamount Province (CISP), an oceanic area off NW Africa including 16 main seamounts, the Canaries archipelago and the Selvagens subarchipelago. The Bank is located 90 km northeast of Lanzarote Island and has been identified as a candidate Marine Protected Area (MPA) to be included in the Natura 2000 network. A compilation of complementary datasets consisting of multibeam bathymetry, TOPAS seismic reflection profiles, side scan sonar sonographs, Remotely Operated Vehicle video records and seafloor samples allowed describing in detail and ground truthing the submarine landforms and bioconstructions exhibited by the bank. The Concepcion Bank presently rises up to 2,433 m above the adjacent seafloor and exhibits two main domains: an extensive summit plateau and steep flanks. The sub-round summit plateau is 50km by 45 km and ranges from 158 to 1,485 m depth. The steep flanks that bound it descend to depths ranging between 1,700 and 2,500 m and define a seamount base that is 66km by 53 km. This morphology is the result of constructive and erosive processes involving different time scales, volumes of material and rates of change. The volcanic emplacement phase probably lasted 25-30 million years and was likely responsible for most of the 2,730 km3 of material that presently form the seamount. Subsequently, marine abrasion and, possibly, subaerial erosion modulated by global sea level oscillations, levelled the formerly emerging seamount summit plateau, in particular its shallower (<400 m), flatter (<0.5°) eastern half. Subsidence associated to the crustal cooling that followed the emplacement phase further contributed the current depth range of the seamount. The deeper and steeper (2.3°) western half of Concepcion Bank may result from tectonic tilting normal to a NNE-SSW fracture line. This fracture may still be expressed on the seafloor surface at some scarps detected on the seamount's summit. Sediment waves

  16. American Meteor Society Fireball reporting system and mobile application

    NASA Astrophysics Data System (ADS)

    Hankey, M.

    2014-07-01

    The American Meteor Society (AMS) founded in 1911 pioneered the visual study of meteors and has collected data relating to meteor observations and bright fireballs for over 100 years. In December 2010, the online fireball reporting system was upgraded to an interactive application that utilizes Google Maps and other programmatic methods to pinpoint the observer's location, azimuth and elevation values with a high degree of precision. The AMS has collected 10s of 1000s of witness reports relating to 100s of events each year since the new application was released. Three dimensional triangulation methods that average the data collected from witnesses have been developed that can determine the start and end points of the meteor with an accuracy of <50 km (when compared to published solutions provided by operators of all sky cameras). RA and DEC radiant estimates can also be computed for all significant events reported to the AMS. With the release of the mobile application, the AMS is able to collect more precise elevation angles than through the web application. Users can file a new report directly on the phone or update the values submitted through a web report. After web users complete their fireball report online, they are prompted to download the app and update their observation with the more precise data provided by the sensors in the mobile device. The mobile app also provides an accurate means for the witness to report the elapsed time of the fireball. To log this value, the user drags the device across the sky where they saw the fireball. This process is designed to require no button click or user interaction to start and stop the time recording. A count down initiates the process and once the user's phone crosses the plane of azimuth for the end point of the fireball the velocity timer automatically stops. Users are asked to log the recording three times in an effort to minimize error. The three values are then averaged into a final score. Once enough

  17. GREAT optics

    NASA Astrophysics Data System (ADS)

    Wagner-Gentner, Armin; Graf, Urs U.; Philipp, Martin; Rabanus, David; Stutzki, Jürgen

    2004-10-01

    The German REceiver for Astronomy at Terahertz frequencies (GREAT) is a first generation PI instrument for the SOFIA telescope, developed by a collaboration between the MPIfR, KOSMA, DLR, and the MPAe. The first three institutes each contribute one heterodyne receiver channel to operate at 1.9, 2.7 and 4.7 THz, respectively. A later addition of a e.g. 1.4 THz channel is planned. The GREAT instrument is developed to carry two cryostats at once. That means that any two of the three frequencies can be observed simultaneously. Therefore, we need to be able to quickly exchange the optics benches, the local oscillator (LO) subsystems, and the cryostats containing the mixer devices. This demands a high modularity and flexibility of our receiver concept. Our aim is to avoid the need for realignment when swapping receiver channels. After an overview of the common GREAT optics, a detailed description of several parts (optics benches, calibration units, diplexer, focal plane imager) is given. Special emphasis is given to the LO optics of the KOSMA 1.9 THz channel, because its backward wave oscillator has an astigmatic output beam profile, which has to be corrected for. We developed astigmatic off-axis mirrors to compensate this astigmatism. The mirrors are manufactured in-house on a 5 axis CNC milling machine. We use this milling machine to obtain optical components with highest surface accuracy (about 5 microns) appropriate for these wavelengths. Based on the CNC machining capabilities we present our concept of integrated optics, which means to manufacture optical subsystems monolithically. The optics benches are located on three point mounts, which in conjunction with the integrated optics concept ensure the required adjustment free optics setup.

  18. Petrology of ultramafic xenoliths from Loihi Seamount, Hawaii

    USGS Publications Warehouse

    Clague, D.A.

    1988-01-01

    Ultramafic xenoliths were recovered in four alkalic lava flows from Loihi Seamount at depths between 2200 and 1400 m. No xenolith bearing flows were sampled near the summit despite a concentrated dredge program. The flows, three of alkalic basalt and one of basanite, contain common olivine megacrysts and small xenoliths of dunite, rarer harzburgite, and a single wehrlite. Olivine megacrysts as large as 8 mm are Fo84-88.6 and contain magnesiochromite inclusions with 1.1-3.5 wt.% TiO2. Dunite contains Fo83.5-88.5 olivine, meganesiochromite with 1.5-6.9 wt.% TiO2 (avg. 3.2 wt.), and extremely rare chrome-rich diopside. The wehrlite contains euhedral Fo85.9 olivine and magnesiochromite with 1.9-4.7 wt.% TiO2, poikilitically enclosed in chrome-rich diposide (Wo45.4En48.0s6.6). Most of the olivine megacrysts, dunite, and the wehrlite are cumulates of Loihi alkalic lavas that accumulated in a magma storage zone located at least 16 km below sea level. The rarity of dunite related to tholeiitic magmas supports the interpretation that the alkalic lavas at Loihi generally predate the tholeiitic lavas. -from Author

  19. Quantifying the eruption cycle at Axial Seamount using submarine geodesy

    NASA Astrophysics Data System (ADS)

    Nooner, S. L.; Chadwick, B.

    2011-12-01

    Bottom pressure instruments within the caldera of Axial Seamount recorded subsidence during eruptions in 1998 and again in April 2011, for a total repeat time of 13 years. We present here a summary of the vertical deformation history at Axial and describe what that tells us about changes in magma supply over an entire eruption cycle. Over the last 13 years we have used a combination of continuously recording bottom pressure recorder (BPR) instruments and campaign style mobile pressure recorder (MPR) surveys to document changes in the elevation of the caldera floor. These observations of caldera deformation directly reflect changes in the magmatic system throughout the entire volcanic eruption cycle. Rapid inflation of the volcano (>50 cm/yr) started immediately after the 1998 eruption and began slowing exponentially within a few months, ultimately transitioning to a constant linear inflation rate of 15 cm/yr that continued until the 2011 eruption. We interpret these two different inflation regimes as the surface manifestation of two entirely different recharge mechanisms within the magma chamber: 1) Short-duration poroelastic flow and viscoelastic relaxation immediately following eruption, and 2) Long-term linear recharge from the mantle. The second mechanism suggests that long-term flow rates from the mantle are controlled by permeability rather than pressure at Axial. Finally, we present evidence that the pattern of deformation at Axial can be used as a method of forecasting future eruptions here.

  20. Quantitative Approach To Seamount Volumes And Eruption Rates For Serpentinite Mud Volcanoes

    NASA Astrophysics Data System (ADS)

    Fedenczuk, T.; Fryer, P.

    2008-12-01

    Serpentinite mud volcanoes in the Mariana forearc are formed by the hydration of mantle peridotite with slab- derived fluids. We calculated the volumes of five seamounts (Pacman, Celestial, Conical, Turquoise, and Big Blue Seamounts) using bathymetric, and (where available) multi-channel seismic reflection data. We interpolated the underlying pre-emplacent surfaces of each seamount using three methods (kriging, harmonic, and multiquadratic radial function), and three estimation techniques to define the pre-eruption seafloor surface beneath the seamounts (perimeter outline, wide area grid, and a geologically interpreted subsurface). We compared the percent difference between each. The interpolation methods produced volume results that differ as follows: 1.9% between kriging and the multiquadratic radial function, 3.6% between kriging and the harmonic function, and 3.8% between multiquadratic radial and the harmonic function. The techniques for determining the subsurface had larger percent differences as follows: 22% between the wide area grid and the geologic interpretation, 20% between geologic interpretation and the perimeter technique, and 18% between wide area grid and the perimeter technique. Based on linear regression results with a high R2, we conclude that there is a strong correlation between the results provided by all three methods. Based on the similarity of all of the regression slopes and their proximity to 1, we can conclude that no method will consistently over- or underestimate the volumes. The geologic interpretation technique should be used when subsurface data (seismic, drill cores, etc.) is available, or when workers have a strong geologic understanding and/or experience in the area. The other two techniques (perimeter and wide area grid) may be useful for large scale comparison studies that include many tens or hundreds of seamounts (or other features), where time constraints and a need for a systematic and repeatable approach is required, or