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  • GEOPHYSICS  (21,936)
  • 1
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    In:  Other Sources
    Publication Date: 2019-04-02
    Description: At the last International Reference Ionosphere (IRI) Workshop it was decided that future editions of the model should include a representationof the aurroral oval boundaries. In this paper we review the different existing parameterizations of the auroral oval discussing their data base, boundary criteria, matematical formation, and overall usefulness for IRI. As a first candidate for incorporation into IRI we recomment the parameterization of the Feldstein ovals by Holzworth and Meng. Ways of implementing this model into IRI are discussed. We will also address adjustability with user-provided boundaries or boundary-related parameters, to better support strom-related studies.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 16; 1; p. (1)13-(1)16
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  • 2
    Publication Date: 2019-03-13
    Description: Airborne laser radar studies of molecular and aerosol density of lower atmosphere
    Keywords: GEOPHYSICS
    Type: NASA-TN-D-5558
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  • 3
    Publication Date: 2019-01-29
    Description: Satellite tracking system intercomparisons based on GEOS 2 satellite data - GEOS 2 program conference
    Keywords: GEOPHYSICS
    Type: NASA-TM-X-67272
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  • 4
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    In:  CASI
    Publication Date: 2019-01-29
    Description: Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. Examples are given of coordinated programs in Alaska which involve satellites, radars, ground optical instrumentation, and other types of observing satellites for the study of auroras.
    Keywords: GEOPHYSICS
    Type: NASA-CR-138156
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  • 5
    Publication Date: 2019-01-29
    Description: Proceedings of conference on significant results obtained by ERTS-1 - Vol. 2
    Keywords: GEOPHYSICS
    Type: E73-10825 , NASA-TM-X-66283 , X-650-73-127
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  • 6
    Publication Date: 2019-01-29
    Description: Conservation laws and preferred frames in relativistic gravity
    Keywords: GEOPHYSICS
    Type: NASA-CR-127277 , OAP-284
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  • 7
    Publication Date: 2019-01-29
    Description: Gravimetric and geometric investigations with GEOS 1 and GEOS 2 - GEOS 2 conference
    Keywords: GEOPHYSICS
    Type: NASA-TM-X-67271
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  • 8
    Publication Date: 2019-01-29
    Description: The author has identified the following significant results. The supply, demand, and impact relationships of California's water resources as exemplified by the Feather River project and other aspects of the California Water Plan are discussed.
    Keywords: GEOPHYSICS
    Type: E74-10621 , NASA-CR-138731
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  • 9
    Publication Date: 2019-01-29
    Description: Summaries are presented on the use of ATS-1 data to analyze low frequency oscillations of the earth's magnetic field and hydromagnetic wave polarization.
    Keywords: GEOPHYSICS
    Type: NASA-CR-138802
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  • 10
    Publication Date: 2019-01-29
    Description: Skylab data has been used: (1) as an aid to resource management in Northern California; (2) to assess and monitor change in the Southern California environment; and (3) for resource inventory and analysis of The California Desert Program.
    Keywords: GEOPHYSICS
    Type: E74-10495 , NASA-CR-136899
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  • 11
    Publication Date: 2019-01-29
    Description: University of California investigations to determine the usefulness of modern remote sensing techniques have concentrated on the water resources of the state. The studies consider in detail the supply, demand, and impact relationships.
    Keywords: GEOPHYSICS
    Type: NASA-CR-136945
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  • 12
    Publication Date: 2019-01-29
    Description: The University of California has been conducting an investigation which seeks to determine the usefulness of modern remote sensing techniques for studying various components of California's earth resources complex. Most of the work has concentrated on California's water resources, but with some attention being given to other earth resources as well and to the interplay between them and California's water resources.
    Keywords: GEOPHYSICS
    Type: E74-10136 , NASA-CR-136181
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  • 13
    Publication Date: 2019-01-29
    Description: Conference on significant results obtained from ERTS-1 MSS and RBV data - Vol. 3
    Keywords: GEOPHYSICS
    Type: E73-10826 , NASA-TM-X-66284 , X-650-73-155
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  • 14
    Publication Date: 2019-01-29
    Description: Integrated study of California resource complex through remote sensing from aircraft and spacecraft and socio-economic factors affecting resource management
    Keywords: GEOPHYSICS
    Type: NASA-CR-125828
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  • 15
    Publication Date: 2019-01-29
    Description: Procedures and techniques for determining earth resources from high altitude aircraft and Apollo 9 photographs
    Keywords: GEOPHYSICS
    Type: NASA-SP-275 , LC-73-170325
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  • 16
    Publication Date: 2019-01-29
    Description: Conference on Earth Resources Program including geology and geography
    Keywords: GEOPHYSICS
    Type: NASA-TM-X-66913
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  • 17
    Publication Date: 2019-01-29
    Description: Studying geology, geochemistry, and biology of Iceland and Surtsey as examples of new and extreme environments
    Keywords: GEOPHYSICS
    Type: NASA-TM-X-62009
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  • 18
    Publication Date: 2019-01-25
    Description: The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth-viewing sensor being developed as a facility instrument for the Earth Observing System (EOS) to be launched in the late 1990s. MODIS consists of two separate instruments that scan a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, Sun-synchronous, platform at an altitude of 705 km. Of primary interest for studies of atmospheric physics is the MODIS-N (nadir) instrument which will provide images in 36 spectral bands between 0.415 and 14.235 micrometers with spatial resoulutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean and atmosperhic processes. The intent of this lecture is to describe the current status of MODIS-N and its companion instrument MODIS-T (tilt), a tiltable cross-track scanning radiometer with 32 uniformly spaced channels between 0.410 and 0.875 micrometers, and to describe the physical principles behind the development of MODIS for the remote sensing of atmospheric properties. Primary emphasis will be placed on the main atmospheric applications of determining the optical, microphysical and physical properties of clouds and aerosol particles form spectral-reflection and thermal-emission measurements. In addition to cloud and aerosol properties, MODIS-N will be utilized for the determination of the total precipitable water vapor over land and atmospheric stability. The physical principles behind the determination of each of these atmospheric products will be described herein.
    Keywords: GEOPHYSICS
    Type: In: The use of EOS for studies of atmospheric physics; Proceedings of the International School of Physics (Enrico Fermi), Course 115, Varenna, Italy, Jun. 26 - Jul. 6, 1990 . A95-89225; p. 253-285
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  • 19
    Publication Date: 2019-01-25
    Description: Magellan radar imaging and topography data are now available for a number of volcanoes on Venus greater than 100 km in radius. These data can be examined to reveal evidence of the flexural response of the lithosphere to the volcanic load. On Venus, erosion and sediment deposition are negligible, so tectonic evidence of deformation around large volcanoes should be evident except where buried by very young flows. Radar images reveal that most tectonic features and flow units on the flanks of these volcanoes have predominantly radial orientations. However, both Tepev Mons in Bell Regio and Sapas Mons in Atla Regio exhibit circumferential graben on their flanks. In addition, images reveal several flow units with an annular character around the north and west flanks of Tepev Mons. This pattern most likely results from ponding of flows in an annular flexural moat. Maat Mons in Atla Regio and Sif Mons in Eistla Regio are examples of volcanoes that lack circumferential graben and annular flows; discernible flow units and fractures on these constructs appear to be predominantly radial. Altimetry data can also provide evidence of flexural response. Tepev Mons is partially encircled by depressions that may be sections of a flexural moat that has not been completely filled. The locations of these depressions generally coincide with the annular flows described above. There is weaker evidence for such depressions around Maat Mons as well. The lack of circumferential tectonic features around most volcanoes on Venus might be explained by gradual moat filling and coverage by radial flows. The depressions around Tepev (and possible Maat) may indicate that this process is currently continuing. We use analytic models of plate flexure in an axisymmetric geometry to constrain the elastic plate thickness supporting Tepev Mons. If we consider the outer radius of the ponded flows to be the edge of a moat, we find that models with elastic plate thickness of 10-20 km fit best. Finite element models of a volcanic load detached from the underlying lithosphere predict overthrusting and radial normal faulting at the volcano's edge. Such a mechanism for the formation of radial rift zones on Venus volcanoes would make such features analogous to structures on the flanks of volcanoes on Earth.
    Keywords: GEOPHYSICS
    Type: Tectonic History of the Terrestrial Planets; 1 p
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  • 20
    Publication Date: 2019-01-25
    Description: A preliminary paleomagnetic study of the impact breccia matrix and clasts has produced surprising results--nearly antipodal normal and reversed polarity magnetic vectors are observed in different portions of the core. Near-antipodal magnetizations within a segment of matrix and within individual samples rule out core inversion as the explanation of the dual polarity. In both the dense and the sandy matrix breccias, the magnetizations of clasts and matrix within the same core segment are identical; this negative 'conglomerate test' indicates that magnetization originated after impact. Paleomagnetic study of the Manson Impact Structure is an attempt to refine the Ar-40/Ar-39 age (65.7 +/- 1 m.y.) that suggests Manson to be a Cretaceous-Tertiary boundary impact. Refinement is possible because the boundary occurs within a reversed polarity interval (29R) of only 0.5 m.y. duration. The two breccia types in the Manson structure were both examined: one of a very dense matrix and apparently partially melted, and the breccia stratigraphically below it of granular or 'sandy' chloritic matrix. Samples were taken from the matrixes and a wide variety of clast compositions, including granite, diabase, gneiss, amphibolite, and melted granite. Currently, measurements have been made on 22 samples, using 30-35 steps of either alternating field (AF) or thermal demagnetization.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1347-1348
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  • 21
    Publication Date: 2019-01-25
    Description: The determination of the shape and size of terrestrial impact craters is problematic, yet is critical to understanding cratering mechanics and for scaling bolide mass, volume, and impact velocity with crater size and target response. The problem is particularly difficult in older geological terrains (e.g. Precambrian) which are more likely to have suffered post-impact deformation and hence distortion of the original structure and/or where weathering may have partly removed or obscured its original shape. Traditionally, a number of features are used to assist us in determining the shape and size of an impact structure. These include the following: (1) the occurrence of faults, especially those disposed concentrically relative to the crater--the outermost ring faults being interpreted as indicating a viable minimum diameter; and (2) the development of so-called breccias, some of which are also associated with faults (e.g. the Sudbury Breccia developed within the target rocks of the Sudbury Structure of Onta rio, Canada). 'Breccia' is not a satisfactory term because a number of breccia-types exist at impact sites (e.g. fall-back breccias and in-situ brecciated target material). Of relevance to crater diameter determination is the recognition of discrete zones and fault- and shock-related pseudotachylyte. Pseudotachylyte is a rock type comprising a fine-grained, usually dark matrix containing clasts of minerals and/or rock derived from the country rock target material. It origin is normally attributed to high-speed slip (including vibration) along a slip surface (i.e. fault) or to the passage of a shock wave through the host material. The clasts can occur as angular fragments (i.e. like a breccia), but are more commonly developed as rounded to sub-rounded fragments. Significantly, the scale of these pseudotachylytes can range from sub-millimeter thick veinlets to dyke-like bodies up to 1 km or more thick. It is the latter, larger occurrence which has been referred to as 'breccia.' The smaller-sized occurrence is generally not recognized in the field, nor is it traditionally associated with its larger counterpart.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1335-1336
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  • 22
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    In:  Other Sources
    Publication Date: 2019-01-25
    Description: There is evidence that the terrestrial magnetic field is connected with the Earth's mantle: (1) there are magnetic anomalies that do not take part in the westward drift of the main field, but are fixed with respect to the mantle; (2) the geomagnetic pole position flips in a particular way by preferred meridional paths during a reversal; and (3) magnetic polarity reversals are correlated with the activations of geological processes. These facts may be explained if we take into account that a significant horizontal temperature gradient can exist in the top levels of the liquid core because of the different thermoconductivity of the different areas of the core-mantle boundary. These temperature inhomogeneities can penetrate the core because fluxes along the core boundary (the thermal wind) can be strongly suppressed by a small redistribution of the chemical composition in the top of the core. The nonparallel gradients of the temperature, density, and composition on the top of the core create a curled electric field that produces a current and a magnetic field. This seed-field can be amplified by motions in the core. The resulting field does not forget the seed-field distribution and in this way the field on the Earth surface (that can be created only in regions with high conductivity, i.e. in the core) is connected with the core-mantle boundary. Contrary to the usual approach to the dynamo problem, we will take into account that the seed field of thermoelectric origin is acting not only at some initial moment of time but permanently.
    Keywords: GEOPHYSICS
    Type: Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 413-414
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  • 23
    Publication Date: 2019-01-25
    Description: A popular, as well as scientifically rigorous, scenario for the origin of life on Earth involves the production of organic molecules by interaction of lightning (or other forms of energy) with a chemically reducing atmosphere in the early history of Earth. Experiments since the 1950's have convincingly demonstrated that the yield of organic molecules is high when the atmosphere contains molecular hydrogen, methane, ammonia, and water vapor. Additional work has also shown that such a highly reducing atmosphere might not, however, have been sufficiently long-lived in the presence of intense solar ultraviolet radiation for life to have formed from it. One way of maintaining such an atmosphere would be to have a continual replenishment of the reduced gases by prolonged volcanic outgassing from a reducing of Earth's interior. The length of time that this replenishment might need to continue is in part constrained by the flux of asteroids onto the Earth's surface containing sufficient energy to destroy most, if not all, life that had developed up to that point in time. If a reducing atmosphere is a key ingredient for the origin of life on Earth, the time of the last environmental sterilization due to large impacts would be an important constraint. In a deep marine setting (e.g., hydrothermal vent), the last global sterilization might have occurred at 4200-4000 Ma. On the Earth's surface, the last global sterilization event might have occurred at 4000-3700 Ma. If these are meaningful constraints, how likely is it that a reducing atmosphere could have survived on the Earth until about 3800 Ma ago? Due to the importance of replenishing this atmosphere with reducing components by volcanic outgassing from the mantle, geochemical information on the history of the mantle's oxidation state would be useful for addressing this question. Geochemical and experimental data discussed in this abstract suggest that extrusive mafic volcanics derived from the upper mantle have had oxidation states near the fayalite-magnetite quartz buffer throughout the last 3800 Ma. At magmatic temperatures, the gases released from volcanoes having this oxidation state would have been, as they are today, composed dominantly of carbon dioxide and water vapor, and would not contain the ingredients for maintaining a reducing atmosphere. Consequently, geochemical data do not favor the survival of a reducing atmosphere until about 3800 Ma. Alternative venues and pathways for the origin of life need to be investigated (e.g., hydrothermal vents along oceanic ridges).
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 395-396
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  • 24
    Publication Date: 2019-01-25
    Description: Magnetite-wuestite spherules collected from deep-sea sediments are thought to have originally been Fe-Ni metal particles at the top of the atmosphere that were oxidized and melted during entry into the earth's atmosphere. Some likely sources for the metal particles are Fe-Ni interplanetary dust particles (IDP's) and metal or sulfide from stony IDP's that separated after melting. Davis et al. reported that four of these spherules are enriched in the heavy isotopes of iron, with enrichments of 8-23%/amu. We have developed a technique for analysis of both iron and nickel isotopes on the same ion microprobe spot and have applied this technique to a number of deep-sea spherules in order to better understand the processes leading to isotopic mass fractionation. Eight spherules show iron and nickel isotopic mass fractionation, with iron and nickel enriched in the heavy isotopes by 10-19%/amu and 4-32%/amu, respectively. If the mass fractionations are due to Rayleigh fractionation during evaporation, these spherules lost 76-94% of their original mass. We have analyzed the four magnetite-wuestite spherules for which iron isotopic data were reported by Davis et al. as well as four new spherules.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 373-374
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  • 25
    Publication Date: 2019-01-25
    Description: The K/T boundary sequence is exposed in uplifted carbonate sediments of the southwest peninsula of Haiti. It is found at 15 localities within the Beloc formation, a sequence of limestone and marls interpreted as a monoclinal nappe structure thrust to the north. This tectonic deformation has affected the K/T boundary deposit to varying degrees. In some cases the less competent K/T deposit has acted as a slip plane leading to extensive shearing of the boundary layer, as well as duplication of the section. The presence of glassy tektites, shocked quartz, and an Ir anomaly directly link the deposit to a bolide impact. Stratigraphic and sedimentological features of the tripartite sequence indicate that it was formed by deposition from ballistic fallout of coarse tektites, emplacement of particle gravity flows and fine grained fallout of widely dispersed impact ejecta.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 251-252
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  • 26
    Publication Date: 2019-01-25
    Description: This study aims at quantifying the effect of rheology on the plan-view shapes of lava flows. Plan-view shapes of lava flows are important because they reflect the processes governing flow emplacement and may provide insight into lava flow rheology and dynamics. In our earlier investigation, it was reported that plan-view shapes of tholeite basalts are fractal, having a characteristic shape regardless of scale. It was also found one could use the fractal dimension (a parameter which quantifies flow margin convolution) to distinguish between the two major types of basalts: a'a and pahoehoe. Encouraged by these earlier results, a similar method for use on silicic flows are being developed and our preliminary work is presented.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 207-208
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  • 27
    Publication Date: 2019-01-25
    Description: Coarse, spherule-bearing, elastic units have been discovered at 10 marine sites that span the K/T boundary in northeastern Mexico. We examined one of the best exposed sites in Arroyo el Mimbral, northwest of Tampico. The Mimbral outcrop displays a layered elastic unit up to 3 m thick enclosed by marly limestones of the Mendez (Latest Maastrichian) and Velasco (Earliest Danian) Formations. At its thickest point, this channelized elastic unit is comprised of 3 subunits: (1) a basal, poorly-sorted, ungraded calcareous spherule bed 1 m thick containing relict impact glass and shocked mineral grains, (2) a massive set of laminated calcite-cemented sandstones up to 2 m thick with plant debris at its base, (3) capped by a thin (up to 20 cm) set of rippled sandstone layers separated by silty mudstone drapes containing a small (921 pg/g) iridium anomaly. This tripartite elastic unit is conformably overlain by marls of the Velasco Formation. We also visited the La Lajilla site east of Ciudad Victoria; its stratigraphy is similar to Mimbral's, but its elastic beds are thinner and less extensive laterally. The Mimbral elastic unit has been interpreted previously as being deposited by a megawave or tsunami produced by an asteroid impact on nearby Yucatan (Chicxulub crater). However, a presumed 400-m paleodepth of water at the Mimbral site, channeling of the spherule subunit into the underlying Mendez Formation marls, and the overtopping of the basal, spherule-bearing subunit by the laminated sandstone subunit, all suggest a combined debris flow/turbidite origin for this elastic unit similar to that proposed for Upper Pleistocene sand/silt beds occurring elsewhere in the Gulf of Mexico. In this latter model, the sediment source region for the elastic unit is the lower continental shelf and slope escarpment. For the K/T unit at Mimbral, we propose that thick ejecta blanket deposits composed mostly of spherules were rapidly loaded onto the lower shelf and slope from an impact-generated ejecta curtain.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 143-144
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  • 28
    Publication Date: 2019-01-25
    Description: Models of most magmatic processes, including realistic models of planetary lava flows require accurate data on the rheological properties of magma. Previous studies suggest that field and laboratory rheological properties of Hawaiian lavas can be calculated from their physico-chemical properties using a non-Newtonian rheology model. The present study uses new measurements of the rheological properties of crystallizing lavas to show that this is also true for lavas from Mount Etna. Rheological measurements on quenched Etna basalts were made in a specially designed furnace using a Haake Rotovisco viscometer attached to a spindle which has been designed to eliminate slippage at the melt-spindle interface. Using this spindle, we have made measurements at lower temperatures than other workers in this field. From these measurements, Mount Etna lavas are Newtonian at temperatures above 1120 C and they are thixotropic pseudoplastic fluids with a yield strength at lower temperatures. The close agreement between calculated and measured rheology over the temperature range 1084 - 1125 C support the use of the non-Newtonian rheology model in future modeling of planetary lava flows.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1149-1150
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  • 29
    Publication Date: 2019-01-25
    Description: The approximately 180-km-diameter Chicxulub crater lies buried by approximately 1 km of sediment on the northwestern corner of the Yucatan Peninsula, Mexico. Geophysical, stratigraphic and petrologic evidence support an impact origin for the structure and biostratigraphy suggests that a K/T age is possible for the impact. The crater's location is in agreement with constraints derived from proximal K/T impact-wave and ejecta deposits and its melt-rock is similar in composition to the K/T tektites. Radiometric dating of the melt rock reveals an age identical to that of the K/T tektites. The impact which produced the Chicxulub crater probably produced the K/T extinctions and understanding the now-buried crater will provide constraints on the impact's lethal effects. The outstanding preservation of the crater, the availability of detailed gravity and magnetic data sets, and the two-component target of carbonate/evaporites overlying silicate basement allow application of geophysical modeling techniques to explore the crater under most favorable circumstances. We have found that the main features of the gravity and magnetic field anomalies may be produced by the crater lithologies.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1105-1106
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  • 30
    Publication Date: 2019-01-25
    Description: The objective is to obtain UV, visible, and near-IR reflectivity spectra for several magnetic Brazilian soils/rocks and compare them to corresponding data for Mars to see if these materials satisfy both magnetic and spectral constraints for Mars. Selected physical properties of the magnetic Brazilian soils/rocks are presented. In general, the spectral features resulting from ferric crystal-field transitions are much better defined in the spectra of the magnetic Brazilian soils/rocks than in Martian spectral data. Presumably, this results from a relatively higher proportion of crystalline ferric oxides for the former. The apparent masking of the spectral signature of maghemite by hematite or goethite for the Brazilian samples implies the magnetic and spectral constraints for Mars can be decoupled. That is, maghemite may be present in magnetically-significant but optically-insignificant amounts compared to crystalline hematite.
    Keywords: GEOPHYSICS
    Type: Program and Abstracts for Clay Minerals Society 28th Annual Meeting; p 161
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  • 31
    Publication Date: 2019-01-25
    Description: POLE (Polar Ozone Lidar Experiment) is a cooperative project between the French and Italian services. It was started with the implementation of a first depolarization backscattering lidar for measurements both of background stratospheric aerosols and Polar Stratospheric Clouds (PSCs). A complex Ozone lidar was also installed which will replace the backscattering system and extend its measurements to tropospheric and stratospheric Ozone and to stratospheric and mesospheric temperatures. This new system allows also the measurement of the backscattered and depolarized signal produced by PSCs and background aerosols. The depolarization technique seemed to be quite efficient in the detection of different types of PSCs.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Research Center, International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects; p 51-53
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  • 32
    Publication Date: 2019-01-25
    Description: Lidar backscatter soundings of stratospheric aerosol layer were routinely made at the IFU, Garmisch-Partenkirchen. After 1979 significant perturbations of the stratosphere were observed after volcano eruptions from 1980 to 1985. A volcanically quiescent period followed until the eruption at the end of 1989. Determinations of particle extinction, mass and surface area of the stratospheric particulate load are important in climatic considerations and heterogeneous chemistry effects. Balloon-borne particle counter measurements are used to derive height and time resolved conversion factors to convert lidar backscatter data to extinction, mass and surface area values. This is done by combining particle size distributions with Mie backscatter and extinction functions. These conversion factors are applicable to midlatitude lidar observations and were used to convert ruby lidar measurement at the IFU.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Research Center, International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects; p 50
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  • 33
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    In:  Other Sources
    Publication Date: 2019-01-25
    Description: Validation of observations is an important part of any remote sensing program. With respect to aerosols this is exceedingly difficult because each technique typically measures a different aerosol parameter. Correlative sensors, therefore, must be capable of measuring the same parameter over the same size range or include enough measurements to properly characterize the aerosol, possibly with the assistance of models. In any correlative measurement program, simultaneity in space and time is required. This can be less restrictive during periods of atmospheric stability. The discussion is presented which is focused on the validation programs developed for NASA's Stratospheric Aerosol Measurement (SAM II), and the Stratospheric Aerosol and Gas Experiments I and II (SAGE I and II). To date these were limited to the stratosphere. Since satellite sensors are capable of providing near-global and long-term observations, periodic correlative observations over various global locations and seasons are required for assuring that data quality is unchanged, or for understanding any changes observed.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Research Center, International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects; p 49
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  • 34
    Publication Date: 2019-01-25
    Description: Measurements of acidic and basic gases that coexist with fine particle (less than 2.5 micron) may be useful for determining the impact of these species on global climate changes and determining species that influence stratospheric ozone levels. Annular denuders are well suited for this purpose. A new concentric annular denuder system, consisting of a three channel denuder, a Teflon coated cyclone preseparator, and a multistage filter pack was developed, evaluated, and shown to provide reliable atmospheric measurements of SO2, HNO2, HNO3, NH3, SO4(=), NH4(+), NO3(-), and H(+). For example, the precision of the annular denuder for the ambient measurements of HNO3 and nitrates at concentrations between 0.1 to 3 microgram/cu m was + or - 12 and 16 pct., respectively. The 120 x 25 mm three channel denuder is encased in a stainless steel sheath and has annular spaces that are 1 mm wide. This design was shown to have nearly identical capacity for removal of SO2 as conventional 210 x 25 mm single channel denuder configurations. The cyclone preseparator was designed and tested to have a D sub 50 cutoff diameter of 2.5 micron and minimal retention of HNO3.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Research Center, International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects; p 41
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  • 35
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    Publication Date: 2019-01-25
    Description: Following preliminary investigations of the low frequency electric and magnetic fields that may exists in the Earth-ionospheric cavity, measurements were taken with state-of-the art spectrum analyzers. As a follow up to this activity, an investigation was initiated to determine sources and values for possible low frequency signal that would appear in the cavity. The lowest cavity resonance is estimated at about 8 Hz, but lower frequencies may be an important component of our electromagnetic environment. The potential field frequencies produced by the electron were investigated by a classical model that included possible cross coupling of the electric and gravitation fields. During this work, an interesting relationship was found that related the high frequency charge field with the extremely low frequency of the gravitation field. The results of numerical calculations were surprisingly accurate and this area of investigation is continuing. The work toward continued development of a standardized monitoring facility is continuing with the potential of installing the prototype at West Virginia State College early in 1990. This installation would be capable of real time monitoring of ELF signals in the Earth-ionoshpere cavity and would provide some directional information. A high gain, low noise, 1/f frequency corrected preamplifier was designed and tested for the ferrite core magnetic sensor. The potential application of a super conducting sensor for the ELF magnetic field detection is under investigation. It is hoped that a fully operational monitoring network could pinpoint the location of ELF signal sources and provide new information on where these signals originate and what causes them, assuming that they are natural in origin.
    Keywords: GEOPHYSICS
    Type: Maryland Univ., The 1989 NASA-ASEE Summer Faculty Fellowship Program in Aeronautics and Research; p 27
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  • 36
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    Publication Date: 2019-01-25
    Description: The planetary boundary layer (PBL) is the lowest layer of the atmosphere in contact with the Earth's surface. It plays an important role in atmospheric circulation and dynamics by influencing surface fluxes of moisture, heat, and momentum. The PBL is characterized by its turbulence structure. Organized convection within the PBL may generate gravity waves within the free troposphere. These waves can propagate vertically, modifying global circulation. Remote sensing of the PBL using a downward-looking lidar is providing new insight into dynamic processes of this important layer and its connection with wave generation. An airborne lidar is an ideal tool to study the PBL. The lidar is installed on the NASA Electra aircraft. It consists of a frequency doubled Nd:YAG laser aligned with a 40 cm diameter telescope. As the laser beam propagates downward from the aircraft toward the surface, it is scattered by the aerosols and molecules in the atmosphere. Generally, there is a sharp gradient of aerosol scattering associated with the PBL top, with high aerosol scattering from within the PBL, and generally very low scattering from the free atmosphere above. It is this gradient in aerosol scattering that is used to visualize the structure of the PBL. A small portion of the scattered radiation is collected by the telescope, filtered, detected by a photomultiplier, and digitized at 100 nsec rate. The horizontal resolution is typically around 13 m, using a 10 Hz laser and a nominal aircraft moves, the resolution of features in the atmosphere below the aircraft is about 15 x 13 m. Results from several studies are presented and discussed.
    Keywords: GEOPHYSICS
    Type: NASA, Washington, 4th Airborne Geoscience Workshop; p 43
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  • 37
    Publication Date: 2019-01-25
    Description: The response of mesospheric ozone and temperature to short term solar ultraviolet variations related the the 27 day rotation of the Sun has been recently detected from analysis of satellite measurements. A systematic depletion of ozone was detected near 70 km, which is attributed to solar Lyman alpha photodissociation of water vapor with subsequent catalytic destruction of O(x) by HO(x) and temperature feedback effects resulting from the unexpectedly strong temperature/UV response near 70 km. The nature of latitudinal and semiannual variations in the ozone/UV and temperature/UV response were isolated. Observed variations are compared to theoretical models.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 67
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  • 38
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Optical Society of America, Topical Meeting on Laser and Optical Remote Sensing: Instrumentation and Techniques. Technical Digest Series, Volume 18; p 218-221
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  • 39
    Publication Date: 2019-01-25
    Description: There are given results of the numerical experiments on modelling the influence of solar activity on chemical composition and temperature of the middle atmosphere. The consideration is made for peculiarities of solar activity impact under different values of antropogenic pollution of the atmosphere with chlorofluorocarbons and other stuff.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 117
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  • 40
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    Publication Date: 2019-01-25
    Description: An inverse Poisson integral technique was used to determine a gravity field on the geoid which, when continued by analytic free space methods to the topographic surface, agrees with the observed field. The computation is performed in three stages, each stage refining the previous solution using data at progressively increasing resolution (1 x 1 deg, 5 x 5', 5/8 x 5/8') from a decreasing area of integration. Reduction corrections are computed at 5/8 x 5/8' granularity by differencing the geoidal and surface values, smoothed by low-pass filtering and sub-sampled at 5' intervals. The 1 x 1 deg averages of the reduction corrections thus obtained for 172 1 x 1 deg squares in western North America are discussed. The 1 x 1 deg mean reduction corrections are predominantly positive, varying from -3 to +15 mgal, with values in excess of 5 mgal for 26 squares. Their mean and rms values are +2.4 and 3.6 mgal respectively and they correlate well with the mean terrain corrections. The mean and rms contributions from the three stages of computation are: 1 x 1 deg stage +0.15 and 0.7 mgal; 5 x 5' stage + 1.0 and 1.6 mgal; and 5/8 x 5/8' stage +1.3 and 1.8 mgal. These results reflect a tendency for the contributions to become larger and more systematically positive as the wavelengths involved become shorter. The results are discussed in terms of two mechanisms; the first is a tendency for the absolute values of both positive and negative anomalies to become larger when continued downwards and, the second, a non-linear rectification, due to the correlation between gravity anomaly and topographic height, which results in the values continued to a level surface being systematically more positive than those on the topography.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 107
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  • 41
    Publication Date: 2019-01-25
    Description: Present crustal evolution models fail to account for the generation of the large volume of continental crust in the required time intervals. All Archaean plate tectonic models, whether invoking faster spreading rates, similar to today's spreading rates, or longer ridge lengths, essentially propose that continental crust has grown by island arc accretion due to the subduction of oceanic crust. The petrological differences that characterize the Archaean from later terrains result from the subduction of hotter oceanic crust into a hotter mantle. If the oceanic crust was appreciably thicker in the Archaean, as geothermal models would indicate, this thicker crust is surely going to have an effect on tectonic processes. A more valid approach is to compare the possible styles of convergence of thick oceanic crust with modern convergence zones. The best modern analog occurs where thick continental crust is colliding with thick continental crust. Oceanic crustal collision on the scale of the present-day Himalayan continental collision zone may have been a frequent occurrence in the Archaean, resulting in extensive partial melting of the hydrous underthrust oceanic crust to produce voluminous tonalite melts, leaving a depleted stabilized basic residuum. Present-day island arc accretion may not have been the dominant mechanism for the growth of the early Archaean crust.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Growth of Continental Crust; p 168
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  • 42
    Publication Date: 2019-01-25
    Description: If plotted on mass vs time diagrams, geologic entities (for example, continental and oceanic crust, sediments, and mineral resources) display an exponential (power law) relationship, with entity per unit time increasing toward the present. This relationship is consistent with the concept of recycling and can be simulated mathematically. The approach is based on the plate tectonic theory and considers area-age or mass-age distributions of crystalline basement and sediments for major global tectonic realms. Each tectonic realm is characterized by a specific lifespan, which is an inverse function of its recycling rate. The estimated average half-area of half-mass ages are given. The corresponding parameters for continental crust are 690 Ma for K/Ar, and approximately 1200 Ma for Rb/St and U-Th/Pb dating pairs. Tectonic diversity preserved in the geologic record is therefore a function of time, with oceanic tectonic realms, because of their rapid recycling, underrepresented in the rocks older than approximately 300 Ma. The Sm/Nd isotopic systematic of sediments suggest that, for a near steady-state post-Archean sedimentary mass, recycling is approximately 90 + or - 5 percent cannibalistic. This yields an estimated upper limit on crust-mantle exchange via sediment subduction of approximately 1.1 + or - 0.5 x 10 g a(sup -1) considerably less than demanded by isotopic constraints. The discrepancy may indicate the existence of additional loci, such as orogenic belts, for significant crust-mantle interaction.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Growth of Continental Crust; P 156
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  • 43
    Publication Date: 2019-01-25
    Description: Large Ion Lithophile (LIL) depletion in Lewisian granulites is discussed. Severe depletions in U, Th, and other LIL have been well documented in Lewisan mafic and felsic gneisses, but new Pb isotopic analyses show little or no depletion in lithologies with high solidus temperatures, such as peridotite. This suggests that LIL transport in this terrane took place by removal of partial melts rather than by pervasive flooding with externally derived CO2. The Pb and Nd isotopic data gathered on these rocks show that the depletion and granulite metamorphism are distinct events about 250 Ma apart. Both fluid inclusions and cation exchange geothermometers date from the later metamorphic event and therefore have little bearing on the depletion event, suggesting a note of caution for interpretations of other granulite terranes.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Growth of Continental Crust; p 48
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  • 44
    Publication Date: 2019-01-25
    Description: Experimentalists, data analysts, and theoreticians were brought together to study and interpret the results of four solstice campaigns conducted prior to the symposium. Emphasis was placed on campaigns III and V. Topics discussed included: review of the data and evaluation of the consistency with available theoretical models; interpretation of the data; recommendations on how the Atmospheric Tides Middle Atmosphere Program (ATMAP) results should reach the open literature such that the advancement of middle atmosphere science and the proprietary rights of the individual experimenters are best served; and recommendations concerning future campaigns and the future emphasis of ATMAP.
    Keywords: GEOPHYSICS
    Type: Middle Atmosphere Program. Handbook for Map, volume 21; p 12-55
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  • 45
    Publication Date: 2019-01-25
    Description: Topics addressed include: methods of tidal analysis; tidal climatologies for the month of December and June; guidelines for construction of monthly climatologies; and future plans.
    Keywords: GEOPHYSICS
    Type: Middle Atmosphere Program. Handbook for MAP, volume 21; p 65-69
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  • 46
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 483-489
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  • 47
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 462-467
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  • 48
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 429-441
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  • 49
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 400-409
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  • 50
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 395-399
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  • 51
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 370-378
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  • 52
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 341-350
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  • 53
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 301-310
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  • 54
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 274-281
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  • 55
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    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 218-236
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  • 56
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 165-174
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  • 57
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 138-146
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  • 58
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 110-116
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  • 59
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 79-86
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  • 60
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 212-213
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  • 61
    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: Illinois Univ. Middle Atmosphere Program. Handbook for MAP. Volume 2: (NASA-CR-175509); p 175-183
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  • 62
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    Publication Date: 2019-01-25
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Programs. Handbook for MAP, Vol. 1; p 39-41
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  • 63
    Publication Date: 2019-01-25
    Description: With the advent of the NASA Space Transportation System, regular flights of a large manned spacecraft, the Space Shuttle Orbiter, became a reality. From the earliest mission containing space science instruments as a payload on the third flight of the Orbiter (STS-3), it became apparent that the disturbance caused by the interaction of this orbiting system with the low Earth orbit (LEO) environment resulted in adverse conditions for the performance of scientific observations of the Orbiter natural environment and for certain high sensitivity optical observations. The interaction of the Space Shuttle Orbiter system can be divided into two parts, the structure-environment interaction, and the outgas cloud-environment interaction. These interaction are briefly discussed.
    Keywords: GEOPHYSICS
    Type: JPL, Space Technology Plasma Issues in 2001; p 309
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  • 64
    Publication Date: 2019-01-25
    Description: A series of workshops were conducted for intercomparison of middle atmosphere data from a variety of sounding systems. The purposes were several: intercomparison of temperature data from various sources: characterization of any observed differences with an attempt to understand those differences, and to provide guidance to users of the data as to the validity of derived quantitites.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, volume 21; p 79-110
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  • 65
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    Publication Date: 2019-01-25
    Description: Highly volatile elements (e.g., T1, Pb, B, C1, Br, etc.) in the Earth's crust occur in C-chondrite proportions, and so do the atmospheric noble gases Ne, Ar, and Kr. This has led to the suggestion that the Earth acquired its volatiles from a late veneer of C-chondrite-like material. A glaring exception is Xe, which is depleted approx. 20x relative to Ne, Ar, Kr. Three explanations are discussed for the depletion: (1) Xe is preferentially trapped in the crust, either in sediments (3) or in Antarctic ice (4); (2) the Earth's noble gas inventory is non-chondritic (5); or (3) Xe is incompletely outgassed from the mantle.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Institute The 47th Ann. Meteoritical Soc. Meeting; 1 p
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  • 66
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    Publication Date: 2019-01-25
    Description: An overview of the OGO program is presented. Brief descriptions of the six OGO spacecraft, and the experiments on each are included.
    Keywords: GEOPHYSICS
    Type: NASA-SP-7601
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  • 67
    Publication Date: 2019-01-25
    Description: Range and structure of atmospheric density from 30 to 120 km - analysis of statistical models and deviations from U.S. standard and Patrick reference atmospheres
    Keywords: GEOPHYSICS
    Type: NASA-CR-61322
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  • 68
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    Publication Date: 2019-01-25
    Description: Solid Earth and Ocean Physics Program plans and recommendations for R and D
    Keywords: GEOPHYSICS
    Type: NASA-CR-1579
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  • 69
    Publication Date: 2019-01-25
    Description: Astrogeologic studies - crater investigations
    Keywords: GEOPHYSICS
    Type: NASA-CR-82745
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  • 70
    Publication Date: 2019-01-25
    Description: Terrestrial test sites and aircraft flights used in preparing for remote sensing from Earth orbital spacecraft
    Keywords: GEOPHYSICS
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  • 71
    Publication Date: 2019-01-25
    Description: Resonant modes of electromagnetic field in dielectric cavity between Earth and ionosphere
    Keywords: GEOPHYSICS
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  • 72
    Publication Date: 2019-01-25
    Description: Magnetic reconnaissance of Sierra Madera, Texas, and nearby igneous intrusions, considering possible meteoritic impact
    Keywords: GEOPHYSICS
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  • 73
    Publication Date: 2019-01-25
    Description: Direct observation of electron precipitation with rockets and satellites, showing that results agree with fluxes predicted from optical measurement of auroras
    Keywords: GEOPHYSICS
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  • 74
    Publication Date: 2019-01-25
    Description: Rocket and satellite investigations of ionospheric electron and ion collision frequencies, solar radiation, D, E and F regions, plasma frequency probe, etc
    Keywords: GEOPHYSICS
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  • 75
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    Publication Date: 2019-01-25
    Description: Orthicon television auroral films indicating more motion and internal structure than is apparent by direct viewing
    Keywords: GEOPHYSICS
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  • 76
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    Publication Date: 2019-01-25
    Description: Different rockets with various payload capabilities for specific upper atmospheric investigations
    Keywords: GEOPHYSICS
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  • 77
    Publication Date: 2019-01-25
    Description: Convective heat transfer data from free flight in wind tunnels
    Keywords: GEOPHYSICS
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  • 78
    Publication Date: 2018-12-01
    Description: A three-dimensional, time dependent current collection model of a satellite has been developed for the TSS-1 system. The system has been simulated particularly for the Research of Plasma Electrodynamics (ROPE) experiment. The Maxwellian distributed particles with the geomagnetic field effects are applied in this numerical simulation. The preliminary results indicate that a ring current is observed surrounding the satellite in the equatorial plane. This ring current is found between the plasma sheath and the satellite surface and is oscillating with a time scale of approximately 1 microsec. This is equivalent to the electron plasma frequency. An hour glass shape of electron distribution was observed when the viewing direction is perpendicular to the equatorial plane. This result is consistent with previous findings from Linson (1969) and Antoniades et al. (1990). Electrons that are absorbed by the satellite are limited from the background ionosphere as indicated by Parker and Murphy (1967).
    Keywords: GEOPHYSICS
    Type: AIAA PAPER 92-2988
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  • 79
    Publication Date: 2019-04-02
    Description: Measurements by single-frequency satellite altimeter (Geosat, ERS-1) require a ionospheric correction to account for the signal time delay in the ionosphere. We propose using the International Reference Ionosphere (IRI) for the determination of this time delay. To investigate the effectiveness of an IRI correction, we have compared the IRI values with ionospheric corrections deduce from measurements by the dual-frequency Topex altimeter. By measuring at two frequencies, the Topex instrument can record (and thus eliminate) the ionospheric influence. We find that IRI agrees with the Topex data much better than the model that is currently used in Geosat data analysis. In particular the earlier model does not represent the equatorial double-peak (equator anomaly) clearly seen in the Topex data. Overall, the use of IRI results in a 30% improvement (over the older model) in the accuracy of ionospheric corrections computed for the first year of the Topex mission.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 15; 2; p. 113-119
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  • 80
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    Publication Date: 2019-04-02
    Description: This paper was presented during the special session that was held at the 1993 International Reference Ionosphere (IRI) Workshop in honor of Karl Rawer's 80th birthday. It retraces the steps that led from the start of the IRI project to the present edition of the model highlighting the important role that the honoree played in guiding IRI from infancy to maturity. All summary view graphs are reproduced at the end of the article.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 15; 2; p. 7-10
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  • 81
    Publication Date: 2019-03-30
    Description: An international conference on high-latitude ionospheric modeling produced 27 papers in the areas of ionospheric mapping, electron density and distribution, ion density and distribution, ionospheric storems, ionospheric composition, and ionospheric sounding techniques. Upgrades to the International Reference Ionosphere (IRI) model were proposed in several papers.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 16; 1
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  • 82
    Publication Date: 2019-03-29
    Description: Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 15; 12
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  • 83
    Publication Date: 2019-03-29
    Description: The main subject of the symposium was 'off-median phenomena'. The title denotes a range of problems that are rarely considered in 'pure science' studies of the ionosphere. The appearance of regular ionospheric variations is well known. Most of these depend on evident solar-geophysical influences like day and night, solar zenith angle, the seasons, geomagnetic control, solar activity, etc. Applicants and theoreticians as well used to work with monthly medians so that the in fact existing and quite important day-to-day variability is systematically overlooked. It is evident that a descriptive model like the International Reference Ionosphere (IRI) would be inadequate if this variability were denied. Interesting contributions from the symposium on 'off-median phenomena' and the IRI are presented.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 15; 2
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  • 84
    Publication Date: 2019-01-29
    Description: Barium releases from Javelin and Nike-Tomahawk sounding rockets for ion cloud study of earth electric and magnetic fields
    Keywords: GEOPHYSICS
    Type: NASA-SP-264
    Format: application/pdf
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  • 85
    Publication Date: 2019-01-25
    Description: Modern Earth science is beginning to examine interactions among the different terrestrial components at all temporal and spatial scales. Such a global perspective requires an integrated remote-sensing program, the Earth Observing System (EOS), which uses instruments throughout the electromagnetic spectrum to collect data about the Earth's surface, oceans and atmosphere over a range of selected scales. At the finest scales, we will require instruments capable of detailed sampling both spatially and spectrally. We have designed the High-Resoulution Imaging Spectrometer (HIRIS) to acquire simultaneous images in 192 spectral bands in the dominant wavelengths of the solar spectrum, 0.4 to 2.5 micrometers, at a spectral sampling interval of 10 nm. The ground instantaneous field of view (GIFOV) will be 30 m over a 24 km swath. A pointing capability will allow image acquisition up to +52 deg/-30 deg down track and +/-45 deg or more cross-track. Thus we will be able to study surface spectral bidirectional reflectance properties and variations in atmospheric attenuation with viewing angle. The cross-track pointing will also allow multiple viewing opportunities during one 16-day orbital revisit cycle, so that any part of the Earth may be imaged in a two-day period.
    Keywords: GEOPHYSICS
    Type: In: The use of EOS for studies of atmospheric physics; Proceedings of the International School of Physics (Enrico Fermi), Course 115, Varenna, Italy, Jun. 26 - Jul. 6, 1990 . A95-89225; p. 287-298
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  • 86
    Publication Date: 2019-01-25
    Description: On Earth, giant radiating dyke swarms are usually preserved as fan-shaped fragments which have been dismembered from their original configuration by subsequent plate tectonic rifting events. Analysis of the largest fragments and consideration of their original configuration has led to the idea that many swarms are plume related, and that dyke swarms radiate away from plume centers. Magellan radar data reveal abundant intact giant radiating swarms on Venus which are similar in scale and pattern to those on Earth. The absence of intense weathering and plate tectonic processes on Venus accounts for the preservation of the primary radiating patterns. It is characteristic of both Earth and Venus that giant radiating dikes are emplaced laterally for distances of at least 2000 km away from plume centers. At distances beyond the influence of the plume on both Earth and Venus, the radiating dyke pattern is often swept into a linear pattern aligned with the regional stress field. There is tremendous potential synergism between the characterization and analysis of terrestrial dyke swarms (where significant erosion has revealed their structure and emplacement directions at depth) and the giant swarms of Venus (where the complete circumferential structure is preserved, and the surface fracture systems above near surface dikes and the nature of the central source regions are revealed). In this study, we report on the characteristics of radial dyke swarms on Earth and Venus and draw some preliminary comparisons from the two perspectives. In summary, on both planets there is evidence for plume-related magmatic centers associated with vertical and lateral injection of magma over considerable distances (up to at least 2000 km). The abundance of very broadly radiating swarms on Venus supports the notion that the swarms on Earth were radiating over broad sectors at the time of intrusion but were dissected by later events. The Venus data show that a swarm can change from radiating (proximal) to regional (distal) subparallel orientations. An implication for Earth is that many regional linear swarms which do not have a radiating pattern may be due to fragmentation of the swarm during later plate tectonic rifting. Completion of the global classification and census of Venus features, comparison to the terrestrial synthesis, and documentation of the mode of emplacement of dikes in these environments (buffered and unbuffered conditions) should lead to additional general insight into mechanisms of formation and evolution and their relation to plumes.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 447-448
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  • 87
    Publication Date: 2019-01-25
    Description: Ancient, stable, continental cratons possess thick, subcontinental-lithospheric mantle 'keels' which favor particularly the emplacement of diamondiferous kimberlites and included peridotites and eclogites. These refractory mantle samples of the roots provide hard constraints on the theories of formation, growth, and evolution of these cratons. Xenoliths containing only primary garnet and clinopyroxene (eclogites), although rare in most kimberlites, can retain the geochemical signatures of their parent protoliths (e.g., subducted oceanic crust, ancient mantle) thus offering the opportunity to address mantle processes which may have taken place at earlier times in the Earth's history. In fact, it has been postulated that some eclogites are residues from the accretion of the early Earth. Nd and Sr isotopic data are presented which may be interpreted as evidence of an early (greater than 4 Ga) mantle differentiation event. The kimberlites of Yakutia are located both marginal and central to the Siberian craton, and a wide variety of xenoliths are present within them. The Siberian mantle samples have received little attention in the western world, largely because suitable suites of Yakutian samples have not been readily available. Importantly, there is evidence that metasomatism of the Siberian lithosphere has been considerably less intense or extensive than for the Kaapvaal craton. Therefore, it should be considerably easier to elicit the igneous/metamorphic histories of Siberian kimberlitic xenoliths. One of the notable features of the Siberian eclogites is the common appearance of diamonds, especially in the Mir and Udachnaya pipes. In all, eight eclogite samples (eight garnet separates and eight clinopyroxene separates) have been analyzed to date on the Udachnaya pipe, seven from our group.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1321-1322
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  • 88
    Publication Date: 2019-01-25
    Description: Drilling of Nx core in late 1953 into an anomalous zone of disturbed rocks northwest of Manson, Iowa disclosed presence of extensive breccias including crystalline rocks brought to the surface from depths of 4 km or more. Hole 2-A penetrated breccias dominated by leucocratic igneous and metamorphic lithologies, later interpreted to be part of a general ringed peak complex within a 35 km wide impact structure produced about 65 Ma ago. Proof of this origin was given in 1966 by NMS through recognition of shock metamorphic features in 2-A materials during a cursory examination of samples provided by R.A. Hoppin, University of Iowa. A detailed study of this material now underway has revealed that most breccia clasts in 2-A show abundant and varied evidence of shock damage, including extensive planar deformation features (PDF) in quartz, K-feldspar, plagioclase, and a pyroxene and varying degrees of isotropization and incipient melting in feldspars.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1303-1304
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  • 89
    Publication Date: 2019-01-25
    Description: At or near the end of the Cretaceous, at least two large impact events occurred in the western hemisphere. One impact formed the 180-km diameter Chicxulub crater on the northern tip of the Yucatan peninsula. Another formed the 35-km diameter Manson structure in western Iowa. Several lines of evidence, including the chemical and isotopic composition of glass found in the K/T boundary layer at sites in the Gulf of Mexico and Caribbean region, the regional variation in thickness and the size of spherules in the K/T boundary layer, and indications at and near the boundary of disturbance and deposition of beds by giant waves in the Gulf of Mexico, point to Chicxulub as a major source of K/T boundary material, including a lower layer of clay at K/T boundary sites in western North America. The size, abundance, and mineral and lithic composition of shocked grains from an upper K/T boundary layer found at western North American sites, on the other hand, point to Manson as a possible source crater. More than one impact seems to be indicated by the K/T boundary stratigraphy in western North America, and present constraints on the age of the Manson structure suggest that it, as well as Chicxulub, may be a K/T boundary crater. Multiple craters produced over a relatively short interval of time are much more likely to have been formed by impact of comets rather than by impact of asteroids. Among likely mechanisms that could have produced multiple craters at or near the time of the K/T boundary are as follows: (1) splitting of a comet shortly before impact with Earth (impacts may have been spaced over about an hour), (2) fragmentation of a very large, Sun-grazing, periodic comet to form a compact stream of comets that intercepted the Earth's orbit (impacts may have been spread over about a century), and (3) perturbation of the Oort comet cloud by a passing massive object to form a comet shower in the inner solar system (impacts may have been spread over about a million years). Only in the first two cases are the impacts likely to have been close enough in time to contribute to the observed K/T boundary layers. All mechanisms could have produced many more than two craters.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1301-1302
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  • 90
    Publication Date: 2019-01-25
    Description: The K-T-aged Chicxulub Impact Structure is buried beneath the Tertiary carbonate rocks of the Northern Yucatan Platform. Consequently its morphology and structure are poorly understood. Reprocessed Bouguer (onshore) and Free Air (offshore) gravity data over Northern Yucatan reveal that Chicxulub may be a 200-km-diameter multi-ring impact basin with at least three concentric basin rings. The positions of these rings follow the square root of 2 spacing rule derived empirically from analysis of multi-ring basins on other planets indicating that these rings probably correspond to now-buried topographic basin rings. A forward model of the gravity data along a radial transect from the southwest margin of the structure indicates that the Chicxulub gravity signature is compatible with this interpretation. We estimate the basin rim diameter to be 204 +/- 16 km and the central peak ring diameter (D) is 104 +/- 6 km.
    Keywords: GEOPHYSICS
    Type: Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1283-1284
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