bluuebunny/crossref_metadata_2025 huggingface dataset:
An improved discriminant for test ban verification using short and long period spectral parameters
Authors: Tjøstheim D. , Husebye E. S.
Published: February 2008

Spectral estimates for Rayleigh and Love waves have been combined with autoregressive parameters for P‐waves and used for discriminating between nuclear explosions and earthquakes in Eurasia. Obtained results using NORSAR data indicate that this new discriminant is superior to the conventional mb∶Ms criterion.
new fine structure cooling rate
Authors: Hoegy Walter R.
Published: February 2008

One of the dominant electron cooling processes in the ionosphere is caused by electron impact induced fine structure transitions among the ground state levels of atomic oxygen. This fine structure cooling rate is based on theoretical cross sections. Recent advances in the numerical cross section determinations to include polarization effects and more accurate representations of the atomic target result in new lower values. These cross sections are employed in this paper to derive a new fine structure cooling rate which is between 40% and 60% of the currently used rate. A new generalized formula is presented for the cooling rate (from which the fine structure cooling rate is derived), valid for arbitrary mass and temperature difference of the colliding particles and arbitrary inelastic energy difference.
On the occurrence of magnetopause crossings at 6.6 RE
Authors: Russell C. T.
Published: February 2008

Examination of slightly over two years of ATS‐1 magnetic field data show that the magnetopause at local noon is within synchronous orbit (6.6 earth radii geocentric) 0.3% of the time.
The effects of the α‐β phase transformation on the creep properties of hydrolytically‐weakened synthetic quartz
Authors: Kirby Stephen H.
Published: February 2008

Nine rectangular prisms of hydro‐thermally‐grown synthetic quartz crystals with 900 atomic ppm H+ were loaded in compression at 1400 bars stress and temperatures between 403 and 764°C. The a and c directions were at 45° to the compression direction, and the slip system
appears to operate over the entire range of temperatures. The strain vs. time curves were sigmoidal in shape; an incubation stage of accelerating creep rates was followed by a hardening stage in which creep rates decreased with time. The creep rate (⋵) vs. temperature (T) data were found to fit very well an Arrehenius law of the form

urn:x-wiley:00948276:media:grl497:grl497-math-0002
where E* is the activation energy for creep. E* is 38.9 ± 2.1 kcal/mole in the α field and 14.3 ± 4.7 kcal/mole in the β field. An offset in the maximum strain rates occurs at the transition temperature, with the β phase creeping at less than half the rate of the α phase. It is suggested that the changes in creep parameters are due to the effects of the inversion on the rates of oxygen diffusion associated with the dissolved water, which hydrolytically weakens the crystals. The α‐β transformation involves rather subtle structural changes. No bond breaking occurs and the change in density is rather small. The transformations responsible for the transition zone of the mantle are reconstructive (involving extensive bond breaking and complete atomic reorganization) and the density changes are large. Thus the potential for large effects of these transformations on creep properties is even greater.
UV stellar occultation measurements of nighttime equatorial ozone
Authors: Riegler G. R. , Atreya S. K. , Donahue T. M. , Liu S. C. , Wasser B. , Drake J. F.
Published: February 2008

The Princeton University Ultraviolet Spectrometer‐Telescope on the NASA Orbiting Astronomical Observatory Copernicus was used for stellar occultation measurements of atmospheric ozone. Two sets of observations of the target star β‐Cen were carried out on 26 July 1975 and 13‐14 June 1976 at wavelengths from 2550Å to 3100Å. After unfolding of the data, ozone density profiles near the equator within 3 hours of local midnight were obtained at altitudes from 47 to 114 km. A secondary maximum at 97 km has been observed in both sets of data. The ozone density between 47 and 75 km is a factor of 2 to 3 times as large as current models predict. At the lower boundary, about half the ozone destruction should be caused by NOx and ClOx. Above 55 km, virtually all loss is due to HOx. These results suggest an overestimate of HOx and ClOx loss processes or a serious underestimate of the Ox production rate. A minimum in O3 density near 87 km and a maximum at about 97 km are probably caused by reactions of O3 with atomic hydrogen and maximum nocturnal O3 production near 97 km.
EUV flux variation during end of solar cycle 20 and beginning cycle 21, observed from AE‐C satellite
Authors: Hinteregger H. E.
Published: February 2008

Minimum levels of solar EUV fluxes appear to have occurred about 14 months before July 1976, the month designated as the start of Cycle 21 (minimum of monthly mean value of sunspot number, RZ). The EUV minimum, observed by the EUVS experiment on AE‐C, occurred around 20 April 1975 under conditions of a spotless disk and of a simultaneous minimum in F10.7. Another rise of quiet‐disk EUV, observed a few months before July 1976, was found in the low‐excitation lines such as 584 Å He I and 1026 Å H Ly‐β. The transition‐region lines of Fe X at 174.5 and 177.2 Å showed a substantial gradual rise later, toward the end of 1976 and mainly in early 1977, when periods of spotless disk with simultaneously minimal F10.7<70 no longer existed. EUV fluxes for days of "high" activity (RZ>30 with F10.7>80) on different sides of the sunspot minimum show drastically different relations to F10.7.
Correlated oxygen and magnesium isotope anomalies in Allende Inclusions, I: Oxygen
Authors: Clayton Robert N. , Mayeda Toshiko K.
Published: February 2008

Two Ca‐Al‐rich inclusions from the Allende meteorite have been found to have undergone large mass‐fractionation of oxygen isotopes subsequent to incorporation of the nucleosynthetic 16O‐anomaly found in other Allende inclusions. The magnitude of the oxygen isotope fractionations is in constant ratio to the magnesium isotope fractionations found in the same inclusions by Wasserburg, Lee and Papanastassiou. The observations support earlier theories of the addition of supernova ejecta into the solar nebula just prior to collapse and condensation.
Non linear sounding of the ionospheric plasma
Authors: Lavergnat J. , Bauer P. , Delahaye J. Y. , Ney R.
Published: February 2008

This paper describes the observation of a ionospheric resonant wave‐wave interaction experiment. The unsolved physical questions, raised by these experiments, and their geophysical implications are presented.
Luna 24: Opaque mineral chemistry of gabbroic and basaltic fragments from Mare Crisium
Authors: Haggerty Stephen E.
Published: February 2008

Spinels and ilmenites are relatively sparse in the Luna 24 gabbro and basalts. Spinel compositions show some affinities to those of spinels in Apollo 12, Apollo 14 and Luna 16 basalts; a characteristic feature is high Al2O3, reaching a maximum of 19.8 wt%. A comparison of spinels in the Luna 24 gabbro with those in other deep‐seated lunar intrusive rocks shows a characteristic trend for Fe/Mg. This trend is systematic from gabbro to anorthosite to troctolite and is interpreted to be P‐T dependent. Compositions of spinels in the gabbro fall within the Cr/Al trend defined by the spinels of the basalts, but form a Fe/Mg trend parallel to that of the basalts; this relationship suggests that both the gabbro and the basalts are derived from a closely similar source region, with the basalts originating at a slightly greater depth than the gabbro. The spinels in both rock types are considered to have formed at high crustal levels, at low pressures. The Luna 24 data suggest that the compositional discontinuities which exist between chromian spinels and titanian spinels in a large proportion of mare basalts are the result of nucleation of chromian spinels at high crustal levels prior to eruption, and of titanian spinels during melt crystallization at the lunar surface.
Earthquake aftershocks as Green's functions
Authors: Hartzell Stephen H.
Published: February 2008

A method is presented for modeling earthquake strong ground motion, which uses the aftershocks associated with a large earthquake as Green's functions. A major earthquake, with a large rupture surface, is modeled by a collection of point sources distributed over the fault plane. The response of each point source is approximated by the ground motion of the closest associated aftershock. By using the aftershock responses, the effects of the true earth structure are included in the modeling process. This method is used to model the El Centro displacement record for the 1940 Imperial Valley earthquake.
Measures of dissipation in viscoelastic media
Authors: O'Connell R. J. , Budiansky B.
Published: February 2008

Various definitions have been adopted for the commonly used quality parameter Q, with consequent ambiguities. We propose a standard definition of the intrinsic Q of a linear viscoelastic material, and discuss its connection with several other measures of dissipation.
Core Formation: Catastrophic or continuous? Sr and Pb isotope geochemistry constraints
Authors: Vidal Philippe , Dosso Laure
Published: February 2008

The negative trend between 87Sr/86Sr and 206Pb/204Pb ratios shown by most oceanic island basalts and the Rb‐Sr and Pb mantle isochrons are ascribed to the end of sulfide segregation, about 2 b.y. ago, in the deep mantle, because this process produces an opposite evolution of µ (238U/204Pb) and Rb/Sr ratios of the residual rocks. These sulfides probably contributed to the core growth. Other isotopic arguments lead to the conclusion of an early and quick core formation; it is, however, proposed here that the core growth continued, but at much slower rate, for ca. 3 b.y. after the initial separation.
Vertical distribution of NO2 in the stratosphere as determined from balloon measurements of solar spectra in the 4500Å region
Authors: Goldman A. , Fernald F. G. , Williams W. J. , Murcray D. G.
Published: February 2008

The stratospheric NO2 mixing ratio profile in the 20‐40 km altitude range is derived from balloon‐borne observations of the solar spectrum in the visible region. By comparisons of high sun and low sun spectra at float altitude (∼40 km), a number of NO2 features are identified. The resulting NO2 profile shows a gradual increase above 20 km to a peak value of 13 ppb(v) near 35 km, followed by a gradual decrease to 10.5 ppb(v) at 40 km.
Interlaboratory calibration of atmospheric nitrous oxide measurements
Authors: Rasmussen R. A. , Pierotti David
Published: February 2008

We conducted an intercalibration program among eleven laboratories making measurements of N2O in the atmosphere in December 1976. The laboratories responding to the intercalibration effort included five in the United States, one in Canada, two in Great Britain, and two in West Germany. The laboratories were in good agreement on the atmospheric concentration of nitrous oxide, with one exception. Excluding the one result which showed an anomalously low value, the other ten laboratories show a mean concentration of 323.5 ± 8.7 ppb v/v N2O for the Northern Hemisphere tropospheric background level for mid‐1976. These results are in agreement with most recent atmospheric measurements of N2O, although some groups have reported values approximately 10% lower. However, the preponderance of recent evidence suggests very strongly that the absolute concentration of nitrous oxide in the troposphere is between 315 and 330 ppb v/v.
Oxygen fugacity of basaltic magmas and the role of gas‐forming elements
Authors: Sato Motoaki
Published: February 2008

It is probable that elemental carbon exists in the source region of a basaltic magma and is suspended in the magma during ascent. As carbon has a large redox capacity, it is probably in control of the magmatic fO2 from the source region to the deep crustal environment. Isothermally carbon becomes more reducing with decreasing pressure, and thus reduces the host magma upon ascent. If a magma is anhydrous (e.g., lunar basalts), the reduction by carbon continues through the extrusive phase and the relative fO2 decreases rapidly until buffered by the precipitation of a metallic phase. If a magma is hydrous (e.g., terrestrial basalts), reduction by carbon is eventually superceded by oxidation due to the loss of H2, which is generated by the reaction of C with H2O and also by the thermal dissociation of H2O, and ferric iron is produced. Cumulus crystallization of ferrous silicates also contributes to the oxidation of magma. The relative fO2 of a hydrous magma initially decreases as the magma ascends from the source region, and then increases until magnetite crystallization curbs the rising trend of the relative fO2.
A method for continuous measurement of radon in water of springs for earthquake prediction
Authors: Friedmann H. , Hernegger F.
Published: February 2008

A method for the continuous measurement of radon in water, which uses a ionisation chamber, is described. The ionisation current (in the range of 10−11 A) is strictly proportional to the radon content in the water. It is supposed that there is a connection between the radon concentration in groundwater and springs and earthquakes. We therefore think that this connection might be used for earthquake prediction. A research project for that purpose had been started in Austria.
The effect of N2+ recombination on the aeronomic determination of the charge exchange rate coefficient of O+(²D) with N2
Authors: Torr D. G. , Orsini N.
Published: February 2008

The Atmosphere Explorer (AE) data are reexamined in the light of new laboratory measurements of the N2+ recombination rate coefficient α. The new measurements support earlier measurements which yielded values of α significantly lower than the AE values. It is found that the values for α determined from the satellite data can be reconciled with the laboratory measurements, if the charge exchange rate coefficient for O+(²D) with N2 is less than one‐quarter of that derived in the laboratory by Rutherford and Vroom [1971]. Atomic oxygen quenching of O+(²D) must be less than 3 × 10−11 cm³s−1.
Constitution of the San Andreas Fault Zone at depth
Authors: Wang Chi‐yuen , Lin Wunan , Wu Francis T.
Published: February 2008

The seismic velocities for the San Andreas fault zone in central California are interpreted in the light of new experimental data for the velocities of compressional and shear waves in fault gouges collected from central California. Under confining pressures the velocities of seismic waves in fault gouge are in the same range as those in a velocity model for the San Andreas fault. Numerical modeling of density in interpreting the gravity anomalies across the fault suggests a zone of relatively low density at depth. These findings indicate that fault gouge may exist down to a depth of 10 km. If this is the case, the mechanical behavior of the San Andreas fault would be greatly influenced by the gouge.
Decomposition of N2O over particulate matter
Authors: Rebbert Richard E. , Ausloos Pierre
Published: February 2008

Nitrous oxide is shown to undergo both a thermal and a photochemical decomposition at 296 K when it is adsorbed on various dry sands. The photochemical process occurs with light of wavelengths greater than 280 nm where gaseous N2O does not absorb. At low pressures (<0.1 torr) the half‐life for the thermal decomposition of nitrous oxide to nitrogen when placed in contact with ∼5 gms of heat treated Tunisian sand in a one‐liter vessel was 350 ± 35 days. Under certain photolytic conditions this half‐life was reduced. The efficiency of the photolytic process for a particular sand depends on the pressure (fraction of surface covered) and on the wave‐length of light. For Tunisian sand at 1.1 torr and with the full mercury arc (>280 nm), the destruction efficiency is ∼2 × 10−5 molecules/incident photon.

These results indicate that particulate matter in the troposphere may be responsible for the decomposition of nitrous oxide and hence act as an atmospheric sink for N2O. However, moisture causes a drastic reduction in the number of molecules dissociated per incident photon.
Estimates of current changes in the geomagnetotail associated with a substorm
Authors: Lui A. T. Y.
Published: February 2008

Magnetic field variations in the near‐earth magnetotail during a weak magnetospheric substorm are studied by two approximate methods to estimate quantitatively the changes in the cross‐tail current. Analysis of the event indicates that the magnetic field variations can be interpreted as a tailward retreat of the cross‐tail current sheet location by ∼0.4‐3.5 RE and an overall reduction of the current density by ∼5‐25%. These changes are accompanied by enhancement of magnetic field‐aligned currents and earthward flowing plasma. The general features of the observations are consistent with the idea that the cross‐tail currents is being diverted into the ionosphere at the substorm onset in association with earthward drainage of plasma in the plasma sheet.
Transmitter simulation of power line radiation effects in the magnetosphere
Authors: Park C. G. , Chang D. C. D.
Published: February 2008

Harmonic radiation from electrical power transmission lines is known to trigger strong emissions in the magnetosphere in the range of a few kilohertz. To study this phenomenon on a controlled basis, an experiment was conducted using a very‐low‐frequency transmitter at Siple, Antarctica (L ≃ 4) and a receiver at its conjugate station, Roberval, Quebec, Canada. Many important features of power‐line‐induced emissions including their frequency dependence, rapid amplitude variations, and spectral forms could be simulated by transmitting waveforms containing sidebands with 50 and 100 Hz frequency separations. It is found that power line effects can be simulated by radiating as little as 0.5 W at a given frequency. The results also demonstrate that the magnetosphere can generate sidebands at frequencies up to 25 Hz from the transmitter frequency. This explains why power‐line‐induced emissions sometimes show frequency components 20‐30 Hz from exact multiples of the fundamental power frequency.
Evidence of an extra‐terrestrial source for the mesospheric sodium layer
Authors: Clemesha B. R. , Kirchhoff V. W. J. H. , Simonich D. M. , Takahashi H.
Published: February 2008

Lidar observations of the mesospheric sodium layer, made at São José dos Campos (23°S, 46°W), show three distinct types of organized structure in the vertical distribution of sodium. Profiles averaged over several days show a smooth but asymmetrical distribution. A sequence of profiles for a given night normally shows a wavelike structure which descends through the layer with time. Very occasionally an extremely narrow peak is observed at a constant height for several hours. On one occasion a layer 2.5 km wide, with scale heights of 700 m on the bottomside and 900 m on the topside, was observed to persist at a constant height for three hours. It is concluded that such a layer could neither be produced by neutral density perturbations nor by photochemical processes and therefore indicates a source of sodium in the mesosphere.
Ultraviolet and infrared absorption cross sections of gas phase HO2NO2
Authors: Graham Richard A. , Winer Arthur M. , Pitts James N.
Published: February 2008

Ultraviolet absorption cross sections for gas‐phase HO2NO2 have been measured from 190 to 330 nm at 269 K and 20 torr total pressure. The HO2NO2 cross sections vary smoothly from 1.6 × 10−17 cm² molecule−1 at 190 nm to ˜2 × 10−20 cm² molecule−1 at 330 nm, and thus photolysis may be the major loss process for HO2NO2 in the stratosphere. High resolution infrared absorptivities for HO2NO2 were also determined in the present study since these data are needed for possible quantitative evaluation of HO2NO2 stratospheric concentrations. The infrared cross sections for the 802.7 and 1304.2 cm−1 Q‐branches of HO2NO2 at 0.06 cm−1 resolution are 2.1 × 10−18 and 1.8 × 10−18 cm² molecule−1, respectively.
The O2 (C³Δu → a¹Δg) bands in the nightglow spectrum of Venus
Authors: Slanger T. G. , Black G.
Published: February 2008

The 4000‐7000 Å nightglow spectrum of Venus, as reported by the Russian Venera 9 and 10 probes, is composed primarily of the 0‐v″ progression of the O2(c¹Σu− → X³Σg−) system. Recent observations in a laboratory afterglow system have established other O2 emissions in the same spectral region. Based on this work, closer scrutiny of the Venera spectrum reveals the presence of the C³Δu → a¹Δg 0−v′ progression, known as the Chamberlain system in the terrestrial airglow, and thus the C³Δu → a¹Δg bands are the first identified O2 emission that is common to both Earth and Venus.²
Origin of the solar‐magnetic‐cycle dependent semiannual variation in galactic cosmic‐ray flux
Authors: Levy E. H.
Published: February 2008

In this paper we point out that the general dipole‐like symmetry of the interplanetary magnetic field produces a heliospheric latitude variation in the density of modulated galactic cosmic rays. This density variation gives the observed semiannual variation in the galactic cosmic‐ray flux observed at Earth, which changes phase with the sign of the solar magnetic field. We derive an explicit expression for the symmetric cosmic‐ray density gradient in the direction perpendicular to the solar equatorial plane and use it to derive a value for the cosmic‐ray diffusion coefficient perpendicular to the average interplentary magnetic field.
The reaction of ClOO with NO
Authors: Wongdontri‐Stuper Wanee , Simonaitis R. , Heicklen Julian
Published: February 2008

Reactions of ClOO with NO were studied by the photolysis of Cl2 in the presence of NO and O2 with or without added N2 using steady state photolysis. ClOO is formed by the reversible reaction The results indicate that ClOO reacts with NO via two channels: The atmospherically important values k2aK1,−1 = (1.5 ± 0.6) × 10−32 cm6 s−1 and k2bK1,−1 = (1.6 ± 1.0) × 10−31 cm6 s−1 were evaluated at 298°K based on the value of (1.1 ± 0.3) × 10−31 cm6 s −1 for the reaction The ratio k2b/k2a was found to be 11.0 ± 2.2. The values of k2aK1,−1 and k2bK1,−1 obtained in the present work when combined with a reasonable value of K1,−1 at stratospheric temperatures indicates that reactions 2a and 2b are probably not important in the stratosphere.
Vortices in magnetospheric plasma flow
Authors: Hones E. W. , Paschmann G. , Bame S. J. , Asbridge J. R. , Sckopke N. , Schindler K.
Published: February 2008

Two‐ and three‐dimensional plasma measurements made in the early morning sector of the plasma sheet with the LASL/MPI analyzers on the ISEE 1 and 2 satellites reveal that the bulk flow of plasma there is sometimes characterized by a pronounced vortical, or circulating motion. Its effect is seen as a recurrent or continuing rotation of the bulk flow vector in a plane sometimes moderately inclined with respect to the ecliptic plane. Remarkably, this rotation has a preferred sense, i.e., clockwise when viewed from above the ecliptic plane. The period for a 360 degree rotation ranges from 5 to 20 minutes and the flow can experience several complete rotations in a relatively uninterrupted sequence. On one occasion this type of behavior of the plasma continued for 9 hours. The speed of the plasma's circulating motion ranges from ∼30 km/sec to ∼200 km/sec. The size of the plasma vortices is estimated as several earth radii. Most of these vortices have been observed during periods of moderate geomagnetic activity. One tentative interpretation of the observations visualizes a "vortex street" convecting earthward along the axis of the magnetotail.
ISEE observations of flux transfer events at the dayside magnetopause
Authors: Russell C. T. , Elphic R. C.
Published: February 2008

Magnetic field measurements from the ISEE 1 and 2 spacecraft are examined in the vicinity of the magnetopause near local noon on a typical pass when the magnetosheath field is southward. The data clearly show evidence for patchy impulsive reconnection. The flux transfer rate for these events is at least of the order of 1 to 2 × 1012 Maxwells per second, and possibly greater. This rate is similar to rates deduced for magnetopause erosion events. Not only are these observations relevant to the substorm process, but the impulsive nature of the flux transfer events leads to boundary oscillations that could also be the source of long period magnetic pulsations in the outer magnetosphere.
Isotopic composition of the anomalous xenon in the Murchison Meteorite
Authors: Smith Stephen P.
Published: February 2008

The calculated isotopic composition of the anomalous new xenon component enriched in 128Xe, 130Xe, and 132Xe discovered by Srinivasan and Anders [1978] in Murchison depends strongly on the technique used to partition the measured spectra among the different components present in the sample. With little a priori justification, Srinivasan and Anders initially assume 134Xe and 136Xe are absent from the new component to derive a composition that matches calculated spectra of xenon produced by s‐process nucleosynthesis. The reported data when plotted on xenon three‐isotope diagrams fall on mixing lines that may be extrapolated to define an allowed range of end point compositions for the new component. This approach to the data yields a well‐defined family of unusual xenon spectra, none of which is the same as the composition obtained by Srinivasan and Anders, and none of which is directly compatible with a component of pure s‐process nucleosynthesis.
Reply to “Isotopic Composition of the anomalous xenon in the Murchison Meteorite” by Stephen P. Smith
Authors: Srinivasan B. , Anders Edward
Published: February 2008

Smith's reinterpretation of the data of Srinivasan and Anders is misleading, because it treats a 4‐component system as a 2‐component system, using a pseudocomponent whose existence, let alone constancy, is at variance with extensive data on Murchison and Allende. The derived "well defined" spectra are of doubtful significance, being based on the fit of a straight line to a curving set of 4 points.
Temporal variation in the attenuation of earthquake coda near Stone Canyon, California
Authors: Chouet Bernard
Published: February 2008

We present evidence of a temporal trend in the attenuation properties of the high frequency coda of local earthquakes near Stone Canyon, central California. The trend appears as a systematic increase in the energy content of the coda of earthquakes with similar magnitudes and locations over a period of about a year. Present theoretical interpretations of the coda do not satisfactorily explain this observation. Possible explanations are considered.
Remote measurement of CℓO in the stratosphere
Authors: Menzies Robert T.
Published: February 2008

CℓO has been detected in the stratosphere from observations of the solar spectrum in the infrared, in a small spectral interval near 12 µm. The observations were made with a balloon‐borne laser heterodyne radiometer, launched from Palestine, Texas on September 20. By comparing high sun spectra with a number of sequential spectra taken during sunset, an altitude profile has been calculated in the 29‐38 km altitude range. The results show a peak mixing ratio in excess of one ppb above 34 km, and a rapid decrease in mixing ratio with decreasing altitude below 34 km.
The role of water content in the magnetization of sediments
Authors: Verosub Kenneth L. , Ensley Ross A. , Ulrick James S.
Published: February 2008

We have developed a new experimental procedure in order to study the role of water content in the acquisition of post‐depositional detrital remanent magnetism by a sediment. The procedure leads to the determination of the magnetic direction recorded by a sediment as a function of the water content present when that sediment experiences a change in the direction of an applied magnetic field. Experiments with a variety of sediments indicate that in most cases, regardless of the water content, the sediment does not become remagnetized. Such behavior requires a re‐assessment of the importance of the theoretical notion that at high water contents the magnetic carriers remain mobile within fluid‐filled voids and hence are able to realign along a new applied field. Analysis of the magnetic properties of sediment samples initially stirred in zero and non‐zero magnetic fields leads to the conclusion that the magnetization of the sediments may arise from small‐scale, shear‐induced liquefaction.
A comparison of the magnetization of detrital and chemical sediments from Lake Zurich
Authors: Giovanoli Federico
Published: February 2008

Glacial clay and silt rhythmites retain a stable remanent magnetization. Their remanence directions yield a clockwise loop with a periodicity of about 400 years. When diagenetically formed iron sulphides are present, then the magnetization direction curves are not correlatable.
Particle flocculation: One possible control on the magnetization of deep‐sea sediments
Authors: Ellwood Brooks B.
Published: February 2008

Anisotropy of magnetic susceptibility measurements have been used to describe the orientations of magnetic grains in sediments from the South Atlantic Ocean. It has been observed that magnetic grain long axis alignment is normal to the expected bottom current direction in the Vema Channel. Traction transport is the inferred mechanism for this alignment. It is proposed here that one possible explanation for this process is sediment aggregation into large floccules (>16 µm), which are of low density due to entrapped water and can therefore become elogated and aligned due to shear produced by bottom currents. The resulting poorly compacted bottom sediment compresses after accumulation of small amounts of overburden. Below ∼ 2 meters the compressed magnetic fabric, residing in the larger magnetic grains, is consistent with expected current deposited primary sedimentary fabric.

The process of particle aggregation, current controlled deposition, compaction, and particle dewatering and breakup can explain the remanent magnetic characteristics observed in some deep‐sea sediments. A DRM inclination error of ∼11°, found at the top of core CH115‐61, disappears with depth in the core; RM inclinations steepen to −50° consistent with an axial geocentric magnetic field inclination for the site. It is suggested that orientations of very small magnetic grains are initially constrained within large floccules and that a DRM inclination error is produced during deposition. Later, floccule disaggregation and dewatering allows realignment of these very small grains along the geomagnetic field direction.
British geomagnetic master curve 10,000‐0 yr B.P. for dating European sediments
Authors: Thompson R. , Turner G. M.
Published: February 2008

Palaeomagnetic inclination records are demonstrated for the first time to be repeatable between lakes. These magnetic variations can now be interpreted with confidence as being a true geomagnetic record. New radiocarbon age determinations refine the time scale of secular changes recorded in Britain over the last 104 years. The paired D & I magnetic measurements form a detailed master curve of 23 features for dating European sediments. The improved records and time scale show that neither the declination nor inclination fluctuations have been periodic. Tight or clockwise looping of the geomagnetic vector has been dominant over Britain since 10,000 B.P.
An explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field
Authors: Kelley M. C. , Fejer B. G. , Gonzales C. A.
Published: February 2008

Anomalous reversals of the zonal equatorial electric field component have sometimes been observed when the interplanetary magnetic field turns northward from a steady southerly direction. We suggest that this reversal is associated with a sudden change in the convection electric field in the magnetosphere and present measurements to support this explanation. Although slower variations in the convection field are shielded from the low latitude ionosphere by polarization charges at the inner edge of the ring current, these charges may require an hour or more to vary. A sudden decrease in the cross‐tail electric field will thus be accompanied by a dusk‐dawn perturbation electric field across the inner magnetosphere.
Determination of the stratospheric residence time from the total β activity of Antarctic and Greenland snows
Authors: Pourchet M. , Pinglot F.
Published: February 2008

The β‐activity in polar snow reflects the combined effects of fallout from and radioactive decay in the stratospheric reservoir of nuclear debris, which has become virtually uniform since the last bomb tests in 1965. This makes it possible to estimate the stratospheric residence time from the decrease in the β activity of snow with age (depth). The residence times thus determined for Antarctica and Greenland average 1.63 years and are in good agreement with published estimates from atmospheric measurements.
The upper mantle transition region: Eclogite?
Authors: Anderson Don L.
Published: February 2008

The upper mantle transition region is usually considered to be peridotite which undergoes a series of phase changes involving spinel and post‐spinel assemblages. There are difficulties associated with attempts to explain the 220, 400 and 670 km discontinuities in terms of phase changes in a peridotitic mantle. Moreover, in a differentiated earth there should be large quantities of eclogite in the upper mantle. Eclogite is denser than Al2O3‐poor mantle to depths of 670 km, but it stays in the garnet stability field to pressures in excess of those required to transform depleted mantle to denser phases such as ilmenite and perovskite. Eclogite, therefore, remains above 670 km. The seismic properties of the transition region are more consistent with eclogite than peridotite. Most of the mantle's inventory of incompatible trace elements may be in this layer, which is a potential source region for some basalt magmas. The radioactivity in this layer is the main source of mantle heat flow, 0.7 µcal/cm² sec, and drives upper mantle convection.
Martian wind activity detected by a seismometer at Viking Lander 2 site
Authors: Nakamura Yosio , Anderson Don L.
Published: February 2008

The seismic ‘background noise’ detected by the seismometer on the Viking lander 2 has an extremely high correlation with the measured wind speed at the landing site. When displayed in a compressed form, the nearly continuous seismic data clearly exhibit the diurnal as well as seasonal variations of the Martian wind activity. A preliminary spectral analysis of the long‐term variation of the background noise indicates persistent spectral peaks at periods near 1.5, 3, 7 and 10‐20 sols for the first 560 sols (0.84 Martian year) of observation.
The Apollo 17 drill core: Comparative modal petrology and phase chemistry of the > 20µm and <20µm soil fractions
Authors: Labotka T. C. , Vaniman D. T. , Papike J. J.
Published: February 2008

We have determined the mode and phase chemistry of the 20‐10µm soil fraction for three levels in the Apollo 17 drill core and compared them to the > 20µm fraction. The results indicate that the 20‐10µm fracton is enriched in Al2O3‐rich clear glass and to a minor extent in olivine and depleted in pyroxene and ilmenite relative to the >20µm fraction. Plagioclase and pyroxene of highland‐type compositions are relatively more abundant in the 20‐10µm fraction as well. These contrasts in mode and phase chemistry explain the enrichment in Al2O3 and depletion in FeO and TiO2 in the <20µm fraction which are observed in bulk chemical analyses of soil fractions. The contribution of highland‐derived material increases with decreasing grain size. Highland material contributes 14% to 30% to the mode of the fused soil‐free 200‐20µm fraction, but 25% to 55% of the fused soil‐free 20‐10µm fraction. The enrichment of highland‐derived material in the finer size fractions can be explained by the finer grain‐size distribution of the more mature highland soil derived from the local massifs. A more effective transport of finer‐grained particles may also contribute to this enrichment but we have no compelling evidence for this effect at the present time.
Possible detection of energetic Jovian heavy ions at Skylab orbit
Authors: Price P. Buford
Published: February 2008

Evidence for the presence of sodium ions at a concentration ∼10% that of oxygen among the particles with energies 10 to 20 MeV/nucleon seen with a detector on Skylab suggests that Jupiter is a significant source of energetic heavy particles inside the earth's magnetosphere. A numerical estimate based on the density of energetic sodium ions at 50 RJ measured on Voyager I indicates that the source strength is adequate.
The ionosphere of Saturn: Predictions for Pioneer 11
Authors: Waite J. H. , Atreya S. K. , Nagy A. F.
Published: February 2008

Model calculations indicate that the lower ionosphere of Saturn is controlled by photochemical processeswith basic features similar to the Jovian ionosphere. The scale height of the upper ionosphere is large (∼3350 km). A peak electron density of ∼105cm−3 2250 km above a 1019cm−3 reference level is expected assuming an eddy coefficient at the homopause of 1.3 × 106cm²s−1 and a relatively hot exosphere at 1300K.
Periodicities in volcanism and longitudinal magma flow on the East Pacific Rise at 23°N
Authors: Lewis Brian T. R.
Published: February 2008

Reflection profiling data across the East Pacific Rise at the mouth of the Gulf of California show an axial high north and an axial valley south of the Tamayo Fracture Zone which converts to a high as one proceeds southwards. On the south side of the fracture zone there is a highly symmetrical distribution of ridges and valleys across the rise axis. Rocks dredged from the ridges are pillow basalts whereas rocks drilled in the valleys on DSDP Leg 65 are massive basalts. It is shown that this axial valley is probably not a steady‐state featurebut rather a periodic feature associated with variations in magma supply rate; the ridges are interpreted as ancient axial highs; and the valleys as ancient axial valleys in which massive basalt flows were ponded. The most recent volcanic ridge appears to be time transgressive suggesting that the volcanic periodicities are associated with longitudinal flow. A consequence of longitudinal flow is that at the fracture zone the flow will be impeded resulting in the observed differences between the rise axis on the north and the south sides of the Tamayo.
Rates of the reactions of 111‐trichloroethane (methyl chloroform) and 112‐trichloroethane with OH
Authors: Jeong Kyu‐Man , Kaufman Frederick
Published: February 2008

Highly purified samples of the two chlorocarbons were reacted with OH over the temperature range 278 to 460 K in a discharge‐flow system with resonance fluorescence detection of OH. Arrhenius expressions within 95% confidence limitsnot including systematic errorsare (5.49 ± 1.40) × 10−12 exp[−(1832 ± 98)/T] cm³ s−1 for CH3CCl3 and (1.57 ± 0.20) × 10−12 exp[−(463 ± 46)/T] cm³ s−1 for CH2ClCHCl2. The important methyl chloroform reaction is slower and its temperature dependence somewhat steeper than earlier measurements had indicatedpresumably due to the presence of faster reacting olefinic impurities in prior studies. Implications for stratospheric ozone reduction by ClOx catalysis and for the tropospheric OH‐budget are discussed briefly.
Latitudinal distribution of the sources of carbon monoxide in the troposphere
Authors: Hameed Sultan , Stewart Richard W.
Published: February 2008

We have constructed a vertically and zonally averaged model of the troposphere which calculates photochemical interactions and diffusive North‐South transport of trace species. The model can be used to calculate the latitudinal distribution of the source function of a species if its concentration distribution is known. We have applied this procedure to carbon monoxide and find large sources outside the industrialized belt in the Northern Hemisphere.
Spatial distribution of plasma in the Io torus
Authors: Bagenal Fran , Sullivan James D. , Siscoe George L.
Published: February 2008

In situ measurements of ion densities and temperatures have been analyzed to produce profiles of these plasma parameters along the Voyager 1 inbound trajectory between 7 and 5 RJ. The temperature profile shows a sharp decrease by a factor of ∼50 between 5.8 and 5.2RJ corresponding to a temperature gradient of ∼7 × 105 per RJ. The electron density profile, inferred from the ion density measurements, has two maxima at 5.7 and 5.3 RJ. A two‐dimensional model of the spatial distribution of various ionic species in the Io plasma torus has been constructed. Using this model a contour map of electron density in a meridional plane has been made, it exhibits a well‐defined inner edge to the torus at 5.6 RJ. The contour map of S+ ion density indicates that most of the S+ ions are concentrated close to the centrifugal symmetry surface and radially inward of the larger electron density maximum near 5.7 RJ.
Ray tracing of Jovian kilometric radiation
Authors: Green James Lauer , Gurnett Donald A.
Published: February 2008

Results of computer ray tracing of Jovian kilometric radiation from 56.2 kHz to 1 MHz in a model Jovian magnetosphere with an Io torus are presented. Ray tracing calculations indicate that the Io torus presents a propagation barrier to the radiation and that the Jovian kilometric radiation must be generated in the L‐O mode from a source near Jupiter on field lines passing through the Io torus. One effect of the Io torus is to refract the rays away from the magnetic equator forming a shadow zone at radial distances beyond the torus. In general, at radial distances greater than 10 Jovian radii, as the wave frequency increases (> 200 kHz) so does the magnetic latitude of the shadow zone. These and other features of the ray tracing calculations are in good qualitative agreement with the observations from the plasma wave receiver and planetary radio astronomy experiment on board both Voyagers 1 and 2.
Airglow measurements of the variation of the O+(²P) ionization frequency during solar cycle 21
Authors: Abreu V. J. , Skinner W. R. , Hays P. B.
Published: February 2008

The ionization rate of O+(²P) ions is determined from measurements of the 7320‐30‐Å emission of O+(²D‐²P) during the development of the present solar cycle. The results compare favorably to the variation of the F10.7 index and to the ionization rate computed using the solar EUV flux as measured by the EUV spectrometer on the Atmosphere Explorer satellites.
Ground radon survey of a geothermal area in Hawaii
Authors: Cox Malcolm E.
Published: February 2008

Rates of ground radon emanation, in the Puna geothermal area on the lower east rift of Kilauea volcano, were measured by alpha particle sensitive cellulose nitrate films. The survey successfully defined an area of thermal significance associated with the rift structure, and suggests that a thermally driven ground gas convection system exists within, and peripheral to, the rift. This type of survey was found suitable for the basaltic island environment characteristic of Hawaii and is now used in Hawaii as a routine geothermal exploration technique.
Large scale three dimensional P velocity structure beneath the western U.S. and the lost Farallon Plate
Authors: Romanowicz Barbara A.
Published: February 2008

The results of a recent large scale three‐dimensional study of P velocity beneath North America are analyzed from the point of view of the search for the fossil Farallon plate in the mantle beneath the western edge of the North American continent.

The large scale velocity structure obtained in the western U.S. is compatible with independent finer scale seismic studies and suggests that the Farallon plate can be traced to depths of 300 to 450 km along the entire North‐South extent of the area. At greater depth, no clear evidence is found for its presence: it has either not reached it or is no longer distinguishable from the surrounding mantle.

On the basis of the 3‐D velocity study we also venture to predict that, whereas in the central and southern part of the western U.S. the top of the plate seems to have sunk to depths in excess of 200 km, it should still be present at shallower depths beneath the Northwestern region. This is in agreement with the progressive migration to the North of the Mendocino transform‐transform‐trench triple junction and its present day position.
Comparison of near coincident LRIR and OAO‐3 measurements of equatorial night ozone profiles
Authors: Gille John C. , Anderson Gail P. , Bailey Paul L.
Published: February 2008

The Limb Radiance Inversion Radiometer (LRIR), the infrared limb scanner on Nimbus 6, obtained equatorial night ozone profiles on 25 and 28 July, 1975, at nearly the same longitudes as the UV stellar occultation measurements made from the OAO‐3 Copernicus observatory on 26 July, 1975. The LRIR determinations agree with many other data sources, but average roughly a factor of 3 lower than the Copernicus results. The LRIR results do not support the suggestion that there are serious gaps in understanding the chemistry of mesospheric ozone.
A stratospheric aerosol increase
Authors: Rosen James M. , Hofmann David J.
Published: February 2008

Large disturbances were noted in the stratospheric aerosol content in the midlatitude northern hemisphere commencing about 7 months after the eruption of La Soufriere and less than 1 month after the eruption of Sierra Negra. The aerosol was characterized by a very steep size distribution in the 0.15 to 0.25 µm radius range and contained a volatile component. Measurements near the equator and at the South Pole indicate that the disturbance was widespread. These observations were made before the May 18 eruption of Mt. St. Helens.
Microwave remote sensing of soil moisture content over bare and vegetated fields
Authors: Wang J. R. , Shiue J. C. , McMurtrey J. E.
Published: February 2008

Remote measurements of soil moisture contents over bare fields and fields covered with orchard grass, corn, and soybean were made during October 1979 with 1.4 GHz and 5 GHz microwave radiometers mounted on a truck. Ground truth of soil moisture content, ambient air and soil temperatures was acquired concurrently with the radiometric measurements. The biomass of the vegetation was sampled about once a week. The measured brightness temperatures over bare fields were compared with those of radiative transfer model calculations using as inputs the acquired soil moisture and temperature data with appropriate values of dielectric constants for soil‐water mixtures. Good agreement was found between the calculated and the measured results over 10°‐70° incident angles. The presence of vegetation was found to reduce the sensitivity of soil moisture sensing. At 1.4 GHz the sensitivity reduction ranged from ∼20% for 10‐cm tall grassland to over 60% for the dense soybean field. At 5 GHz the corresponding reduction in sensitivity ranged from ∼70% to ∼90%.
Lidar measurements of atmospheric lithium
Authors: Jegou Jean‐Pierre , Chanin Marie‐Lise , Mégie Gérard , Blamont Jacques E.
Published: February 2008

The Haute‐Provence Observatory (44° N, 6°E)lidar facility has been extended to study the atmospheric lithium and its isotopic ratio Li7/Li6 in the upper atmosphere. The experimental features have been improved in order to lower the detection limit to 3.105 cm−2 for the total abundance with a resolution of 1.2 km in the altitude profile. The night‐time measurements have been carried out from November 1977 to December 1979 and show some characteristic trends.

The seasonal variation of the total abundance is similar to the one observed for sodium. The altitude profile is variable during the night. Total abundance fluctuations and peaks with small scale heights (1.5 km) are observed on numerous occasions. The layer is sensitive to high‐altitude artificial releases, like CAMEO in November 1978, and to impinging meteor showers. It is concluded that study of the behavior of atmospheric lithium and sodium should further our understanding of the alkali‐metals chemistry.