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Showing papers in "Geophysical Research Letters in 1976"


Journal ArticleDOI
TL;DR: In this article, the authors analyzed the geochemical properties of a chondritic reservoir with high Fe, high Fe basalt, Ti basalt and alkali basalts and compared the results with the present value of the source regions of the earth.
Abstract: ^(147)Sm ɑ-decays to ^(143)Nd so that ^(143)Nd/^(144)Nd reflects the time-integrated Sm/Nd environment of a sample. The increase in 143/144 in a reservoir with chondritic Sm/Nd is 1.2% in 4.5AE. There exists sufficient variation of Sm/Nd to cause sizeable effects in 143/144. Young samples were measured to elucidate the nature of their source regions. An oceanic high Fe, Ti basalt (113152) and alk. basalt (113031), a continental alk. besalt (BCR-l), an apatite (Khibiny massif) and two reagent "normals", NN1 and NN2, were analyzed. Isotopic ratios of NN2 and BCR-1, normalized to 148/144=0.241572 are tabulated. Following the pioneering work of Lugmair, et al. (EPSL 27, 79) our 143/144 data are presented relative to the total rock value for Juvinas (0.51278). the present value of a chondritic reservoir. Data are given as deviations from this value in parts in 10^4 (є) and show a wide range. Nd in the source regions of the rock samples evolved in an environment of approximately chondritic Sm/Nd (±5%) over the history of the earth. Small variations exist, reflecting long time scale differences of Sm/Nd in the source regions. The low Sm/Nd observed in alkali basalts cannot reflect an ancient source region with low Sm/Nd as є is near zero. REE patterns of alkali basalts must thus reflect relatively recent fractionation from a source with essentially chondritic relative abundances. Study of initial ^(143)Nd/^(144)Nd in conjunction with REE patterns promises to contribute important petrogenetic information.

1,106 citations


Journal ArticleDOI
TL;DR: In this article, a priori distinction between "continental" and "oceanic" igneous rocks was made between flood basalts and mid-ocean ridge (MOR) tholeiitic basalts.
Abstract: Continental flood basalts and mid-ocean ridge (MOR) tholeiitic basalts have distinctly different ^(143)Nd/^(144)Nd which may permit a priori distinction between "continental" and "oceanic" igneous rocks. Initial ^(143)Nd/^(144)Nd of continental igneous rocks through time fall on a Sm/Nd evolution curve with chondritic REE abundance ratio. These observations indicate that many continental igneous rocks are derived from a reservoir with chondritic REE pattern which may represent primary material remaining since the formation of the earth. Oceanic igneous rocks are derived from a different ancient reservoir which has Sm/Nd higher than chondritic. Initial ^(143)Nd/^(144)Nd and ^(87)Sr/^(86)Sr in young basalts from both oceans and continents show a strong correlation suggesting that Sm-Nd and Rb-Sr fractionation events in the mantle may be correlative and caused by the same process. From this correlation Rb/Sr for the earth is inferred to be 0.029.

640 citations


Journal ArticleDOI
TL;DR: In this article, it is shown that photodissociation of CSO (and possibly CS2) may provide an interesting stratospheric source of SO2 and further conversion of this SO2 to H2SO4 may contribute significantly to the nonvolcanic background sulfate layer in the stratosphere.
Abstract: Photodissociation of CSO (and possibly CS2) may provide an interesting stratospheric source of SO2 and further conversion of this SO2 to H2SO4 may contribute significantly to the non-volcanic background sulfate layer in the stratosphere. Assuming a tropospheric background volume mixing ratio of 2-3 × 10−10, as indicated by some tropospheric measurements, the input of SO2 in the stratosphere coming from the decay of CSO is estimated to be 6 × 106 - 107 molecules cm−2s−1. Little is known about the sources and sinks of CSO. It is, therefore, clear that, as a matter of caution, a possible growth of industrial releases of CSO (and CS2) into the atmosphere, e.g., from coal combustion, should be watched carefully with regard to their influence on the stratospheric aerosol layer and the earth's radiation balance.

586 citations


Journal ArticleDOI
TL;DR: A satellite-borne ion mass spectrometer experiment has detected fluxes of O/sup+/ and H/sup +/ ions flowing up out of the ionosphere in the auroral and polar regions as discussed by the authors.
Abstract: A satellite-borne energetic ion mass spectrometer experiment has detected fluxes of O/sup +/ and H/sup +/ ions flowing up out of the ionosphere in the auroral and polar regions. The observed ions have energies in the keV range, narrow pitch-angle distributions aligned along the magnetic field direction and peak flux intensities of the order of 10/sup 8/ (cm/sup 2/-sec-sterad-keV)/sup -1/. The observations were made at altitudes between 5000 and 8000 km on both the day and nightsides of the earth. (AIP)

456 citations


Journal ArticleDOI
TL;DR: The magnetic field lines in this sunward sector of the boundary layer are closed, and the plasma flow has a component transverse to the field as mentioned in this paper, which is a site of continual transfer of plasma, momentum and energy from the magnetosheath to the magnetosphere.
Abstract: Observations with the Los Alamos Scientific Laboratory (LASL) plasma probe and the Goddard Space Flight Center (GSFC) magnetometer on the IMP 6 satellite show that the magnetospheric boundary layer, first identified along the flanks of the magnetosphere, is also present at the magnetosphere's sunward surface. The magnetic field lines in this sunward sector of the boundary layer are closed, and the plasma flow has a component transverse to the field. These observations suggest that the boundary layer is a site of continual transfer of plasma, momentum and energy from the magnetosheath to the magnetosphere. These transfer processes supply plasma and magnetic field to the magnetotail. Also, they produce, indirectly, the dawn-to-dusk electric field across the polar cap, the field-aligned currents that border the dayside polar cap, and the soft particle fluxes that characterize the cleft precipitation, including recently reported dawn-dusk asymmetries of these fluxes. Magnetosheath plasma directly enters the outer few hundred to few thousand kilometers of the magnetosphere's surface to form the boundary layer. There it is enabled to flow across the magnetic field (and approximately parallel to the magnetosphere's surface) by becoming electrically polarized. Leakage of the polarization charge along magnetic field lines to the earth produces themore » dayside high latitude effects mentioned above. The polarizing current flowing across the boundary layer interacts with the magnetic field to oppose the boundary layer plasma flow, taking up its momentum. In this way the magnetic field lines are pulled downstream. The process described here is independent of the interplanetary magnetic field (IMF) and thus may constitute the principal transfer mechanism during prolonged periods of northward IMF when the magnetosphere is very quiet. It is not clear how the effects of southward IMF are superposed on this process. (AIP)« less

453 citations


Journal ArticleDOI
TL;DR: In this article, the interaction regions between adjacent solar-wind streams have been identified between 1 and 5 AU by Pioneer 10 and 11 magnetic-field and plasma measurements, and a relatively large fraction of the interactions are accompanied by either forward shocks, reverse shocks, or shock pairs.
Abstract: Interaction regions between adjacent solar-wind streams have been identified between 1 and 5 AU by Pioneer 10 and 11 magnetic-field and plasma measurements. Beyond 1 AU, a relatively large fraction of the interaction regions have been found to be accompanied by either forward shocks, reverse shocks, or shock pairs. The observations are consistent with previous theoretical proposals that the interaction between adjacent streams leads to the development of corotating interplanetary shocks.

416 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported the discovery of a large anomaly in the isotopic composition of Mg in a Ca-Al rich chondrule from the Allende meteorite.
Abstract: We report the discovery of a large anomaly in the isotopic composition of Mg in a Ca-Al rich chondrule from the Allende meteorite. This anomaly is manifest independently of instrumental fractionation and is due to an enrichment of about 1.3 percent in ^(26)Mg while the abundances of ^(25)Mg and ^(24)Mg are terrestrial in value. There is a strong correlation in this chondrule between the ^(26)Mg excess and the Al/Mg ratio so that the most plausible cause of the anomaly is the in situ decay of now extinct ^(26)Al (τ_½ = 0.72 × 10^6 yr). Mineral phases extracted from a Ca-Al-rich aggregate have distinct Al/Mg but show identical, small Mg anomalies which are apparent after correction for fractionation (δ^(26)Mg = 0.3%). These data indicate that this aggregate was isotopically homogenized in a high Al/Mg environment after the decay of ^(26)Al had occurred or that some of the Mg anomalies are due to effects other than in situ decay of ^(26)Al.

345 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported the discovery of a large anomaly in the isotopic composition of Mg in a Ca-Al rich chondrule from the Allende meteorite.
Abstract: The first two paragraphs of this paper were omitted from the January 1976 issue due to an oversight by the AGU Office. We report the discovery of a large anomaly in the isotopic composition of Mg in a Ca-Al rich chondrule from the Allende meteorite. This anomaly is manifest independently of instrumental fractionation and is due to an enrichment of about 1.3 percent in 26Mg while the abundances of 25Mg and 24Mg are terrestrial in value. There is a strong correlation in this chondrule between the 26Mg excess and the Al/Mg ratio so that the most plausible cause of the anomaly is the in situ decay of now extinct 26Al (τ½ = 0.72 × 106 yr). Mineral phases extracted from a Ca-Al-rich aggregate have distinct Al/Mg but show identical, small Mg anomalies which are apparent after correction for fractionation (δ26Mg = 0.3%). These data indicate that this aggregate was isotopically homogenized in a high Al/Mg environment after the decay of 26Al had occurred or that some of the Mg anomalies are due to effects other than in situ decay of 26Al.

342 citations


Journal ArticleDOI
TL;DR: In this paper, the principle of electrokinetic phenomena induced by ground water flow associated with earthquakes is proposed to provide a possible means of earthquake prediction, which may be used for earthquake control by controlling the water flow with an artificial electric potential field.
Abstract: Electrokinetic phenomena induced by ground water flow associated with earthquakes are proposed to provide a possible means of earthquake prediction. Detectable variations of earth currents, electric potential and geomagnetic field may be caused by diffusion of fluid into a dilatant focal region. The principle of electrokinetic phenomena may be used for earthquake control by controlling the water flow with an artificial electric potential field.

329 citations


Journal ArticleDOI
TL;DR: In this article, the power law profile for wind speed is shown to be consistent with observed height variation of Weibull wind speed probability distribution functions which have been found to fit observed wind speed distributions (at least above relevant threshold wind speeds).
Abstract: For use in various wind engineering applications (eg wind energy conversion, wind loads on structures, air pollution transport) it is desirable to have a consistent relationship by which to project height variations of both "instantaneous" (eg few minute average) winds and parameters of the wind speed probability distribution The power law V2/V1 = (Z2/Z1)n is often used for height projection of wind profiles, with the exponent n sometimes taken as depending on surface conditions or on atmospheric stability The power law profile for wind speed is shown here to be consistent with observed height variation of Weibull wind speed probability distribution functions which have been found to fit observed wind speed distributions (at least above relevant threshold wind speeds) For consistency between the wind speed profiles and the height variation of the Weibull wind speed probability distributions, it is necessary only that the exponent n vary as n = a + b ln V1, where a and b are constants whose values depend on the reference height at which wind speed V1 is measured For a reference height of 10 m, it is found that a = 037 and b = −00881 (with V1 in m/s) adequately describes both the observed height variation of wind speed and wind speed probability distributions

287 citations


Journal ArticleDOI
TL;DR: In this article, a numerical simulation of the non-linear evolution of the collisional Rayleigh-Taylor instability using a set of equations appropriate for the equatorial F region ionosphere has been performed.
Abstract: A numerical simulation of the non-linear evolution of the collisional Rayleigh-Taylor instability using a set of equations appropriate for the equatorial F region ionosphere has been performed. Our results show that the irregularities produced by the instability grow on the bottomside of the F region peak, as predicted by linear theory, and then the irregularities nonlinearly bubble through to the topside, where linear theory predicts no irregularities. Fourier analysis of the irregularities show one dimensional power law power spectrum for both the vertical and horizontal directions.

Journal ArticleDOI
TL;DR: In this article, a Rayleigh-Taylor gravitational instability operating on the bottom side of the F peak is explained for strong radar echoes typically observed in patch-like structures at high altitudes.
Abstract: Recent rocket probe, barium cloud and radar measurements conducted during equatorial spread F conditions are interpreted in terms of a Rayleigh-Taylor gravitational instability operating on the bottomside of the F peak. The persistent theoretical problems associated with strong radar echoes typically observed in patch-like structures at high altitudes are explained in terms of regions of depleted plasma density which buoyantly rise against the gravitational field.

Journal ArticleDOI
TL;DR: The detection limit depended on the quality of the photographic exposure and reached 2 · 106 cm−3 in the most favourable cases as mentioned in this paper, while the average detection limit remained below 4 · 106cm−3.
Abstract: OH has been detected in the lower troposphere by optical absorption of the Q1 2 (A²Σ+, v = O, X²Π, v = O) line at 307.995 nm along a 7.8 km path above Julich (51° North, 6° East). The detection limit depended on the quality of the photographic exposure and reached 2 · 106 cm−3 in the most favourable cases. OH generally remained below 4 · 106 cm−3, the average detection limit. But on several occasions during the observation period from mid August to November 1975 concentrations up to 7 · 106 cm−3 were observed.

Journal ArticleDOI
TL;DR: Although Mars' magnetosphere accelerates charged particles, whereas Mercury's magnetosphere apparently does not as discussed by the authors, and this difference results from the fact that rapid steady-state convection, and the associated particle acceleration, cannot occur in a Martian magnetosphere because of its connection to a highly conducting ionosphere.
Abstract: Although Mercury and Mars appear to have magnetospheres of comparable size, Mercury's magnetosphere accelerates charged particles, whereas Mars' magnetosphere apparently does not. We propose that this difference results from the fact that rapid steady-state convection, and the associated particle acceleration, cannot occur in a Martian magnetosphere because of its connection to a highly conducting ionosphere. Mercury, which has no conducting ionosphere and probably an insufficiently conducting surface, can exhibit rapid solar-wind-induced convection and hence particle acceleration in its magnetospheric tail.

Journal ArticleDOI
TL;DR: In this article, the densities of a fertile peridotite (PHN 1611) and a depleted sterile peridotsite(PHN 1569) have been calculated from the cell dimensions of the component minerals, the mineral analyses, and the bulk rock analyses.
Abstract: Densities of a fertile peridotite (PHN 1611) and a depleted sterile peridotite (PHN 1569) have been calculated to be 3.39 and 3.30, respectively. These densities were calculated from the cell dimensions of the component minerals, the mineral analyses, and the bulk rock analyses. Studies of kimberlite nodules suggest that lighter, sterile peridotites overlie heavier, more fertile peridotites uniformly in the upper mantle beneath southern Africa. A temperature difference of 500°C reduces the density of fertile peridotite PHN 1569 to approximately 3.33, which is insufficient to cause it to float in sterile peridotite. However, if fertile peridotite PHN 1569 undergoes 25% partial melting and the garnet is dissolved, its zero pressure density would be reduced to approximately 3.2, which is less than that of depleted, sterile mantle.

Journal ArticleDOI
TL;DR: A rough estimate of the efficiency of fixation yields the value of 1026 NO2 molecules per lightning stroke in this article, where NO2 was observed during a lightning storm by means of absorption spectra associated with NO2.
Abstract: Nitrogen fixation in the atmosphere has been observed during a lightning storm by means of absorption spectra associated with NO2. A rough estimate of the efficiency of fixation yields the value of 1026 NO2 molecules per lightning stroke.

Journal ArticleDOI
TL;DR: In this paper, a nonthermal component in H with a scale height of about 70 km has been observed near the limb off the subsolar point, providing a total apparent number density of 90 per cu cm.
Abstract: Reduction of data from the three Mariner 10 encounters to this date have allowed identification of helium and hydrogen as atmospheric constituents. Subsolar point densities are estimated at 4500 per cu cm for He and 8 per cu cm for the thermal component of H. A nonthermal component in H with a scale height of about 70 km has been observed near the limb off the subsolar point, providing a total apparent number density of 90 per cu cm. Upper limits on other atmospheric constituents have been reduced an order of magnitude. A very tentative identification of O has been obtained but the uncertainty is large and we require further data reduction for confirmation.

Journal ArticleDOI
TL;DR: Using an airborne mounted UV tunable laser system, natural tropospheric OH radical concentrations at 7 and 11.5 km are reported for the first time in this article, where the technique employed was that of Laser Induced Fluorescence where the OH radicals were excited at 2820.6A with the fluorescence being monitored at ∼3095A.
Abstract: Using an airborne mounted UV tunable laser system, natural tropospheric OH radical concentrations at 7 and 11.5 km are here reported for the first time. The technique employed was that of Laser Induced Fluorescence where the OH radicals were excited at 2820.6A with the fluorescence being monitored at ∼3095A. Sampling of the OH was carried out continuously using a laminar flow intake manifold in which the UV laser beam (7mm diameter) was passed through the center core of the gas stream. Measurements at 32° north latitude and 21° north latitude at 7 and 11.5 km revealed significant latitude and altitude variations of the OH radical during the month of October 1975. Details on the importance of these measurements to tropospheric chemistry are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors reported two recent in-situ measurements of ground-state atomic oxygen in the stratosphere between altitudes of 29 and 43 km using a resonance fluorescence technique that was previously employed for the measurement of ground state atomic oxygen.
Abstract: The letter reports two recent in-situ measurements of OH in the stratosphere between altitudes of 29 and 43 km using a resonance fluorescence technique that was previously employed for the measurement of ground-state atomic oxygen. The experimental technique is described in detail along with the photon detector and the absolute-calibration procedure. The results are found to indicate OH concentrations that approach the maximum predicted by current stratospheric photochemical theory.

Journal ArticleDOI
TL;DR: In this article, the authors estimate that the present global production of N2O from coal and fuel oil sources is 1.6 Mtons N 2O(N) per year and is increasing at a rate of ∼ 3.5% per year.
Abstract: Measurements of N2O in the effluent gases from the burning of coal and fuel oil show that these are significant anthropogenic sources of atmospheric N2O. We estimate that the present global production of N2O from these sources is 1.6 Mtons N2O(N) per year and is increasing at a rate of ∼ 3.5% per year. Catalytic converters for the reduction of NO emissions also represent a major potential source of atmospheric N2O.

Journal ArticleDOI
TL;DR: In view of the predicted increases in the combustion of fossil fuels, particularly coal, it is likely that the importance of combustion as a source of atmospheric nitrous oxide will increase as mentioned in this paper.
Abstract: Recent measurements of the exhaust gases in the stacks of power plants burning coal and natural gas have shown high levels of nitrous oxide. Calculations based upon the known combustion parameters of the power plants and extrapolated to the current world production of coal and natural gas indicate that combustion may be a significant source of nitrous oxide in the atmosphere. In view of the predicted increases in the combustion of fossil fuels, particularly coal, it is likely that the importance of combustion as a source of atmospheric nitrous oxide will increase. As a result of the current uncertainty regarding the size of the various sources and sinks of nitrous oxide in the atmosphere, it would appear that the question of the importance of combustion to the atmospheric nitrous oxide budget deserves further scrutiny.

Journal ArticleDOI
TL;DR: In this article, it was shown that the Earth's N2O budget is severely limited, and it may not be excluded, a priori, that not only the source but also its sink is affected by man, and therefore it is essential that a well balanced, interdisciplinary research effort now be designed to increase our knowledge of all aspects of the earth's nutrient cycles.
Abstract: Our understanding of the marine and terrestrial nitrogen budgets is severely limited. For instance, atmospheric data indicate a residence time of N2O in the atmosphere of about 10 years and consequently sources and sinks of atmospheric N2O of the order of 130×106 ton N/year. Such large sources and especially sinks for atmospheric N2O have not been satisfactorily identified and it may not be excluded, a priori, that not only the N2O source, but also its sink is affected by man. The limited knowledge about the earth's N2O budget so far obtained is in favor of the view that there is no imminent danger of large ozone reductions following the predicted increase in the input of fixed nitrogen in the soil by the year 2000. However, it seems likely that, with unchanged agricultural practices, there will develop serious long term problems, certainly in a world of exponential growth, and, for best action, it is essential that a well balanced, interdisciplinary research effort now be designed to increase our knowledge of all aspects of the earth's nutrient cycles.

Journal ArticleDOI
TL;DR: In this article, the authors show a decreasing mixing ratio with altitude in the lower stratosphere, reaching its maximum concentration at an altitude above 21 km (the limiting height of the observations to date).
Abstract: HCl has been observed in both the troposphere and stratosphere from ground-based and airborne spectroscopic measurements of the 1-0 band at 3-micron wavelength. The results, which are specific to the HCl molecule in the gas phase, show a decreasing mixing ratio with altitude in the lower stratosphere. The stratospheric layer, which commences at about 15 km, reaches its maximum concentration at an altitude above 21 km (the limiting height of the observations to date). The local value for the volume mixing ratio at 21 km is 7 + or - 1 times 10 to the minus 10th. However, the zenith column abundance observed above 21 km implies that the mixing ratios at greater altitudes are unlikely to reach values much in excess of the local value at 21 km.

Journal ArticleDOI
TL;DR: In this article, the presence of a temperature inversion near 75 km has been observed at a number of widely scattered locations and on occasion synoptically, and no attempt is made in this note to explain the existence of the inversion.
Abstract: Measurements of temperature in the mesosphere have indicated the occurrence of a temperature inversion near 75 km. Acoustic grenades, falling spheres, thermistors, and pitot probes indicate that this feature also occurs at a number of widely scattered locations, and on occasion has been observed synoptically. No attempt is made in this note to explain the presence of the inversion, only to point out its existence.

Journal ArticleDOI
TL;DR: In this paper, the potential effect of nitrous oxide (N2O) on stratospheric ozone have emphasized the need for research to identify sources and sinks of atmospheric N2O.
Abstract: Recent articles concerning the potential effect of nitrous oxide (N2O) on stratospheric ozone have emphasized the need for research to identify sources and sinks of atmospheric N2O. Work reported shows that soils have a significant capacity for uptake of N2O and may represent an important natural sink for atmospheric N2O. Uptake of N2O by soils is a microbial process involving reduction of N2O to N2. It is promoted by anaerobic conditions and by organic substances that promote growth of soil microorganisms, and it is retarded by nitrate. Studies with nine Iowa surface soils showed that their capacity for uptake of N2O under conditions favorable for denitrification of nitrate was much greater than their capacity for release of this gas.

Journal ArticleDOI
TL;DR: The bulk moduli of silicate and oxide solid solutions depend very little on iron content, but are diagnostic of crystal structure as discussed by the authors, and the upper mantle mineral assemblages as a function of depth are: I. olivine + pyroxene + garnet (200-400 km), II. β-spinel+ pyroxen-garnet solid solution (400-500 km), III. (β + γ) − spinel + pyx-ga s.s.
Abstract: The bulk moduli of silicate and oxide solid solutions depend very little on iron content, but are diagnostic of crystal structure. Comparison of laboratory with seismic data suggests that the upper mantle mineral assemblages as a function of depth are: I. olivine + pyroxene + garnet (200-400 km), II. β-spinel + pyroxene-garnet solid solution (400-500 km), III. (β + γ) − spinel + pyx-ga s.s.(500-600) km, IV. γ-spinel + SiO2 (stishovite) or mixed oxides (650-800 km) and V. mixed oxides or perovskite + MgO(>800 km). The 650 km discontinuity is primarily due to phase changes in the pyroxene-garnet, rather than the olivine, portion of the mantle.

Journal ArticleDOI
TL;DR: Sun-aligned arcs are long and sometimes narrow optical structures which are oriented in the sun-earth direction and which occur in the polar cap, generally during intervals of low magnetic activity as discussed by the authors.
Abstract: Sun-aligned arcs are long and sometimes narrow optical structures which are oriented in the sun-earth direction and which occur in the polar cap, generally during intervals of low magnetic activity. Their appearance, as seen by the DMSP and ISIS-2 satellite photometers, is examined with respect to the north-south orientation of the interplanetary magnetic field. In the DMSP pictures it is found that they appear when the IMF is directed northward. In 16 out of 18 unambiguous observations of sun-aligned arcs by ISIS-2, the IMF was directed northward; for the other two no IMF data was available. These results provide evidence for a strong correlation between the northward direction of the IMF and the occurrence of sun-aligned arcs in the northern polar cap.

Journal ArticleDOI
TL;DR: In this article, the quasi-neutral sheet model of Alfven [1968] as modified by Hill [1974] was studied and the current distribution and the magnetic field reversal were computed compatible with a new invariant of the particle motion.
Abstract: We study the quasi-neutral sheet model of Alfven [1968] as modified by Hill [1974]. If the particle motion is adiabatic the model implies a trapped particle population. In the opposite limit of Speiser [1970] and Eastwod [1972] we compute the current distribution and the magnetic field reversal compatible with a new invariant of the particle motion.

Journal ArticleDOI
TL;DR: In this article, the equation of state and electronic structure of body-centered cubic potassium were investigated theoretically by the quantum-mechanical SAPW method and the results predicted a series of pressure-induced electronic phase changes brought about by the sequential filling of initially unoccupied d-like electronic states.
Abstract: The equation of state and electronic structure of body-centered cubic potassium are investigated theoretically by the quantum-mechanical SAPW method. The results predict a series of pressure-induced electronic phase changes brought about by the sequential filling of initially unoccupied d-like electronic states. In addition to the discontinuous density changes that accompany these phase transitions, the presence of the d-like bands makes potassium extremely compressible. At pressures as low as 500 kb (0°K), the ionic radius of potassium becomes compatible with that of iron and its electronic structure becomes like that of a typical transition metal. These properties should greatly enhance the miscibility of potassium in iron or iron-sulfide melts.

Journal ArticleDOI
TL;DR: A thermal model of the earth's surface has been developed and used to determine the thermal inertia of a test site in the Mojave Desert, California as mentioned in this paper, which can aid in the differentiation of the various lithologic materials in the test site.
Abstract: A thermal model of the earth's surface has been developed and used to determine the thermal inertia of a test site in the Mojave Desert, California. The model, which includes meteorological heating terms as well as radiation and conduction heating terms, is used with remotely sensed surface temperature and reflectance data to determine the thermal inertia of the surface materials at the test site. The thermal inertia is displayed in image form, and can aid in the differentiation of the various lithologic materials in the test site. Since this thermal property is representative of the upper several cm of the surface, it complements visible and reflected near-IR image data.