Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Geophysical”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Satellite-tracking and Earth dynamics research programs

The activities carried out by the Smithsonian Astrophysical Observatory (SAO) are described. The SAO network continued to track LAGEOS at highest priority for polar motion and Earth rotation studies, and for other geophysical investigations, including crustal dynamics, Earth and ocean tides, and the general development of precision orbit determination. The network performed regular tracking of several other retroreflector satellites including GEOS-1, GEOS-3, BE-C, and Starlette for refined determinations of station coordinates and the Earth's gravity field and for studies of solid Earth dynamics. A major program in laser upgrading continued to improve ranging accuracy and data yield. This program includes an increase in pulse repetition rate from 8 ppm to 30 ppm, a reduction in laser pulse width from 6 nsec to 2 to 3 nsec, improvements in the photoreceiver and the electronics to improve daylight ranging, and an analog pulse detection system to improve range noise and accuracy. Data processing hardware and software are discussed.

Source record↗
NASA NTRS1981

Bathymetric and tectonics of Indian Ocean using MAGSAT data

The quality of the MAGSAT data was assessed, especially the characterization of spikes. The spectral passbands of significance to geophysical analysis were analyzed, including computations of spectral coherence between nearby repeating satellite tracks. A spectrum modeling effort was begun which is designed to show the effect of spacecraft attitude on the observability of magnetic anomalies. The data obtained is to be used to compute crustal anomaly maps by modeling the equivalent dipoles in the project area.

Sailor, R. V.↗
NASA NTRS1981

Investigation from Japanese MAGSAT team

The acquisition of tapes which contain vector and scalar data decimated at an interval of 0.5 sec, together with time and position data, is reported. Progress in the study of magnetic anomalies in the vicinity of Japan and in electric currents in the ionosphere and magnetosphere is also reported. MAGSAT data was used in obtaining a map of total force anomaly for the area of latitude 10-70 deg N and longitude 110-170 deg E. One of the outstanding features in the map of the magnetic anomaly is a negative magnetic anomaly in the Okhotsk Sea, which is of geophysical interest because of its possible connection with high heat flow values in that area.

Fukushima, N.↗
NASA NTRS1982

Analyzing the Broken Ridge area of the Indian Ocean using magnetic and gravity anomaly maps and geoid undulation and bathymetry data

A higher resolution anomaly map of the Broken Ridge area (2 degree dipole spacing) was produced and reduced to the pole using quiet time data for this area. The map was compared with equally scaled maps of gravity anomaly, geoid undulation, and bathymetry. The ESMAP results were compared with a NASA MAGSAT map derived by averaging data in two-degree bins. A survey simulation was developed to model the accuracy of MAGSAT anomaly maps as a function of satellite altitude, instrument noise level, external noise model, and crustal anomaly field model. A preliminary analysis of the geophysical structure of Broken Ridge is presented and unresolved questions are listed.

Lazarewicz, A. R.↗
NASA NTRS1982

NOSS Altimeter Detailed Algorithm specifications

The details of the algorithms and data sets required for satellite radar altimeter data processing are documented in a form suitable for (1) development of the benchmark software and (2) coding the operational software. The algorithms reported in detail are those established for altimeter processing. The algorithms which required some additional development before documenting for production were only scoped. The algorithms are divided into two levels of processing. The first level converts the data to engineering units and applies corrections for instrument variations. The second level provides geophysical measurements derived from altimeter parameters for oceanographic users.

Hancock, D. W.↗
NASA NTRS1982

The Nimbus satellite system: Remote sensing R&D platform of the 70's

Originally conceived to be the future operational weather satellite, the Nimbus series of seven satellites became the work horse and experimental backbone of the NASA/NOAA space research program. Early problems in developing the attitude control system and proving its operational characteristics in the simulated space environment are discussed. The program proved itself many times over; contributing substantially to the scientific knowledge of atmospherics and weather. As application/research vehicles, the seven Nimbus spacecraft were used for the development, test and application of a variety of new and advanced meteorological and geophysical remote sensing instruments and associated data transmission and processing techniques.

Haas, I. S.↗
NASA NTRS1981

Integrated and spectral energy flows of the GLAS GCM

Methods to analyze the generation, transport, and dissipation of energy to study geophysical fluid flows are discussed. Energetics analyses are pursued in several directions: (1) the longitudinal and time dependence on the energy flow to the stratosphere was examined as a function of geographical sector; (2) strong and weak energy flows were correlated by medium range forecasts; (3) the one dimensional spectral results (Fourier services around latitude circles) were extended to spherical harmonics over a global domain; (4) the validity of vertical velocities derived from mass convergence was examined for their effect on the conversion of eddy available potential energy to eddy kinetic energy.

Tennebaum, J.↗
NASA NTRS1981

Analyze satellite-tracking laser data in order to study satellite ephemerides, solid-Earth and ocean tides and laser system performance

The decrease in the semimajor axis of Lageos is considerably larger than expected. Gravitational effects, reference system effects, solar radiation pressure, Earth albedo pressure, neutral atmospheric drag, the Poynting Robertson Effect, and electrodynamic effects were used in explaining the observations. Quick look data provided are used to determine the Earth's polar motion and length of day. This process is routine, and provides these geophysical data every five days.

Gaposchkin, E. M.↗
NASA NTRS1981

A survey of the theory of the Earth's rotation

The theory of the Earth's rotation and the geophysical phenomena affecting it is examined. First principles are reviewed and the problem of polar motion and UT1 variations is formulated in considerable generality and detail. The effects of Earth deformations and the solid Earth tides are analyzed.

Cannon, W. H.↗
NASA NTRS1982

The reduction, verification and interpretation of MAGSAT magnetic data over Canada

Correlations between the MAGSAT scalar anomaly map produced at the Earth Physics ranch and other geophysical and geological data reveal relationships between high magnetic field and some metamorphic grade shields, as well as between low magnetic field and shield regions of lower metamorphic grade. An intriguing contrast exists between the broad low anomaly field over the Nasen-Gakkel Ridge (a spreading plate margin) and the high anomaly field over Iceland (part of a spreading margin). Both regions have high heat flow, and presumably thin magnetic crust. This indicates that Iceland is quite anomalous in its magnetic character, and possible similarities with the Alpha Ridge are suggested. Interesting correlations exist between MAGSAT anomalies around the North Atlantic, after reconstructing the fit of continents into a prerifting configuration. These correlations suggest that several orogenies in that region have not completely destroyed an ancient magnetization formed in high grade Precambrian rocks.

Coles, R. L.↗
NASA NTRS1982

Earth Resources: A continuing bibliography with indexes, issue 33

This bibliography list 436 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution sytems, instrumentation and sensors, and economic analysis.

Source record↗
NASA NTRS1982

Satellite tracking and earth dynamics research programs

The SAO laser site in Arequipa continued routine operations throughout the reporting period except for the months of March and April when upgrading was underway. The laser in Orroral Valley was operational through March. Together with the cooperating stations in Wettzell, Grasse, Kootwikj, San Fernando, Helwan, and Metsahove the laser stations obtained a total of 37,099 quick-look observations on 978 passes of BE-C, Starlette, and LAGEOS. The Network continued to track LAGEOS at highest priority for polar motion and Earth rotation studies, and for other geophysical investigations, including crustal dynamics, Earth and ocean tides, and the general development of precision orbit determination. The Network performed regular tracking of BE-C and Starlette for refined determinations of station coordinate and the Earth's gravity field and for studies of solid earth dynamics. Monthly statistics of the passes and points are given by station and by satellite.

Source record↗
NASA NTRS1982

A bibliography of planetary geology principal investigators and their associates, 1981 - 1982

Over 800 publications submitted by researchers supported through NASA's Planetary Geology Program are cited and an author/editor index is provided. Entries are listed under the following subjects: (1) general interest topics; (2) solar system, comets, asteroids, and small bodies; (3) geologic mapping, geomorphology, and stratigraphy; (4) structure, tectonics, geologic and geophysical evolution; (5) impact craters: morphology, density, and geologic studies; (6) volcanism; (7) fluvial, mass wasting, and periglacial processes; (8) Eolian studies; (9) regolith, volatile, atmosphere, and climate; (10) remote sensing, radar, and photometry; and (11) cartography, photogrammetry, geodesy, and altimetry.

Plescia, J. B.↗
NASA NTRS1981

Determining solutions of hyperbolic systems from incomplete data

An investigation is conducted regarding first-order hyperbolic systems of partial differential equations, taking into account problems for which complete initial data are not available. Problems of the considered kind arise in geophysical applications where satellites are used to collect data. In global weather prediction, it is possible to derive atmospheric temperature and pressure reasonably well over the whole globe from satellite measurements; obtaining the wind field globally is more difficult. It is pointed out that a simple model of atmospheric flow investigated in numerical weather prediction is governed by the shallow water equations. The effect of the Coriolis term on the linearized shallow-water equations is studied.

Bube, K. P.↗
NASA NTRS1982

Limits on the lunar temperature profile

Limits on the selenotherm are estimated using (1) a preferred set of bounds on the lunar electrical conductivity profile; (2) published laboratory conductivity vs. temperature data for an olivine and several aluminous orthopyroxenes; and (3) estimates for the Al2O3 content of the deep interior suggested by bulk composition models. The inferred limits are narrowest in the depth range 450 to 1350 km and are in accord with independent geophysical constraints. Thermal history models which yield present-day selenotherms that are in best agreement with these limits are those which permit subsolidus convection at depths greater than 800 km in the moon.

Hood, L. L.↗
NASA NTRS1982

Relationships between the Birkeland currents, ionospheric currents, and electric fields

Currents and electric fields in the ionosphere are calculated using a global model of the electron density including conjugate coupling along field lines. Incoherent scatter and rocket measurements of high-latitude electron densities are used to derive realistic variations of the polar conductivities as a function of magnetic activity. The Birkeland currents are specified in terms of three indices, and the relationship between these parameters and the auroral electrojets indices is examined along with the polar cap potential and the electric field at lower latitudes. A mathematical model of the currents, electric fields, and energy inputs produced by field aligned currents is developed, which is consistent with and specifiable in terms of measured geophysical indices.

Bleuler, E.↗
NASA NTRS1980

A model of early lunar differentiation

The presence of anorthosites and the scarcity of complementary mafic rocks in the lunar crust suggest a body of melt with depth of the order of the depth of the crust itself (about 60 km). This depth is consistent with geophysical and geochemical models which call for a depth of melting of the order of 200-500 km. The major and minor element compositions of the ancient pristine rocks require complex igneous processes if the moon accreted homogeneously and has chondritic interelement ratios among the refractory elements. Anorthosites crystallized from magmas that had assimilated plagioclase and a light REE-enriched component. KREEP as well as most of the troctolites and norites formed from relatively primitive magmas that were mixed with a LIL-enriched, Sc-Ti depleted component. Assimilation and mixing processes inferred for pristine rocks are consistent with crystallization from a convecting magma ocean which initially developed a floating anorthosite crust with a plagioclase-saturated boundary layer beneath it, transitional in temperature and composition to the main body of the magma beneath it.

Longhi, J.↗