bluuebunny/crossref_metadata_2025 huggingface dataset:
Paleomagnetic results from Early Eocene intrusions, north‐central Montana: Implications for North American apparent polar‐wandering
Authors: Diehl J. F. , Beske‐Diehl S. , Beck M. E. , Hearn B. C.
Published: February 2008

Paleomagnetic poles have been determined from two Early Eocene igneous centers located in the north‐central Montana alkalic province. The mean paleomagnetic pole for the Highwood Mountains lies at 81.2°N, 167.3°E (N = 29; α95 = 7.1; k = 15.4) while the corresponding pole for the Bearpaw Mountains is located at 80.5°N, 198.4°E (N = 18; α95 = 5.8; k = 37.0). Combining these results with studies on Eocene rocks from Wyoming, gives a reference pole located at 81.7°N, 171.2°E with a circle of 95% confidence of 4.4°. This data, when compared to other early Tertiary results, the Cretaceous stillstand poles and the well grouped mid‐Tertiary poles from the continental interior, suggest that for the period 120 to 15 m.y.B.P. apparent polar‐wandering for North America occurred as a succession of rapid shifts of the geomagnetic pole separated by periods of stillstand.
A Paleocene paleomagnetic pole for North America from alkalic intrusions, central Montana
Authors: Jacobson D. , Beck M. E. , Diehl J. F. , Hearn B. C.
Published: February 2008

The apparent polar wandering path from Late Cretaceous through early Tertiary time is not well defined. We have collected 33 paleomagnetic sites from the Paleocene Moccasin, Judith, and Little Rocky Mountains and from these a North American Paleocene paleomagnetic pole position has been determined at 174.9°W long., 80.5°N lat., with a circle of 95% confidence of 5.6°. This pole location serves as a Paleocene reference pole and enhances the North American apparent polar wandering path for a critical period of its history.
Particle flux decrease‐increase events at synchronous orbit and the temporal sequence of aurora during substorms
Authors: Erickson K. N. , Winckler J. R.
Published: February 2008

A systematic temporal correlation has been found between the energetic particle intensity variations measured at 6.6 RE and the development of large scale auroral features. The intensification and equatorward drift of eastwest oriented stable discrete homogeneous auroral arc systems coincides with the decrease in energetic particle intensity at 6.6 RE as the nightside magnetosphere develops into a more tail‐like configuration. The subsequent major breakup of the aurora coincides with the recovery in particle intensity as the field returns to a more dipolar configuration. Since this prominent decrease‐increase sequence must be related to the intensification or inward convection of the tail current plasma sheet configuration followed by its diversion or dissipation, the auroral correlation documented here closely links the auroral particle precipitation to the plasma sheet and tail current dynamics.
Possible minimum depths of large historical earthquakes in eastern North America
Authors: Acharya Hemendra
Published: February 2008

For instrumentally recorded earthquakes of magnitude > 5.0 in northeastern North America, focal depth has been estimated using corner periods. Agreement has been noted between these estimates and estimates obtained by assuming a spherical source and using absence of surface faulting as a boundary condition. This suggests that in eastern North America the minimum depth of earthquakes with magnitude mblg ≥ 6.0 would be about 10 km.
Mantle plumes and the thermal stability of the D″ layer
Authors: Yuen D. A. , Peltier W. R.
Published: February 2008

The interpretation of the seismic D″ layer at the base of the mantle as the lower thermal boundary layer of a whole mantle convective circulation has several important geophysical consequences. Because of the strong temperature dependence of mantle viscosity, which sharply reduces the viscosity in the boundary layer itself, this region could be strongly unstable against secondary convective instability. Linear stability analyses presented here show that this destabilization is in fact dramatic, the fastest growing disturbances being characterized by growth times on the order of 106 years and spatial scales on the order of 10² km for a wide variety of plausible lower mantle conditions. The highly nonlinear evolution of the resulting “thermal turbulence” may be such that fastest growing disturbances mature into thermal plumes which rise rapidly to the base of the lithosphere where they may induce intense partial melting.
Stratospheric NO2 at night from stellar spectra in the 440 Nm region
Authors: Naudet J. P. , Rigaud P. , Huguenin D.
Published: February 2008

NO2 was measured in the stratosphere at night by means of a balloon‐borne spectrometer, pointing at a bright rising star, in the 427 to 452 nm range. The vertical distribution of NO2 was deduced using the tangent ray technique between 23 and 38 km. The concentration was (6±1.5)×109 mol.cm−3 at 25 km, passing through a minimum of (2±1)×109 mol.cm−3 at 29 km and rising again up to (4±0.8)×109 mol.cm−3 at 32 km.
Some features of inverted‐V events as seen from simulated double layers
Authors: Singh Nagendra , Thiemann Heinz
Published: February 2008

Results from a numerical simulation of a double layer show some important features of electron fluxes during auroral events; strong heating of the thermal and precipitating electrons is seen. Extremely low frequency fluctuations observed during inverted‐V events are also seen in the simulation. Fluctuations are caused by a relaxation type of oscillation involving the plasma and the instabilities through the formation of cavitons.
On the relationship between secular brightness changes of Titan and solar variability
Authors: Pollack James B. , Rages Kathy , Toon Owen B. , Yung Yuk L.
Published: February 2008

Titan’ geometric albedo varied noticeably from 1972 to 1978, in phase with variations in solar activity [Lockwood and Thompson, 1979]. We carry out a series of radiative transfer and aerosol formation calculations in order to demonstrate the feasibility of the following scenario for these secular brightness changes: solar activity changes, especially in the UV output of the Sun, result in alterations to the mass production rate of aerosols in Titan’s atmosphere, which lead to modifications of their microphysical properties. The latter, in turn, cause the albedo to vary. Current estimates of the change in the solar UV radiation below the dissociation limit of methane imply alterations to the mean radius of the aerosols over an 11‐yr solar cycle that are consistent in sign and magnitude with those required to explain the observed secular brightness changes.
Stimulation of Pc 1 geomagnetic pulsations by naturally occurring repetitive VLF activity
Authors: Fraser‐Smith A. C. , Helliwell R. A.
Published: February 2008

Several different mechanisms have been suggested for the natural stimulation of Pc 1 geomagnetic pulsation events. These mechanisms include hydromagnetic noise in the magnetosphere, bursts of radiation from high‐energy charged particles, or sferics from lightning discharges. Guided by the results of experiments to generate Pc 1 pulsations by VLF transmissions into the magnetosphere, and by the theory that has been developed in support of these experiments, we now propose a new mechanism: the stimulation of Pc 1 pulsation events by naturally occurring repetitive VLF signals. The VLF signals may be echoing whistlers, periodic chorus elements, or other periodic or quasiperiodic VLF wavetrains echoing along a geomagnetic field line. Preliminary support for this hypothesis is provided by a comparison of the Pc 1 pulsations and VLF activity occurring at Roberval, Quebec, during 9 intervals of simultaneous Pc 1 pulsation and VLF measurement.
On the effect of parallel electric fields on chorus
Authors: Brinca Armando L.
Published: February 2008

Consideration of a geomagnetic‐field‐aligned electric field
in the nonlinear evolution of the cyclotron resonance between electrons and parallel whistler mode waves modifies the conditions required to phase trap energetic particles. Assuming that the deeply trapped, long interacting electrons play the major role in the emissions generated by this nonlinear cyclotron resonance, we utilize a simple phenomenological mechanism to study the influence of the electric field on the ground spectral shapes of equatorial chorus. The alterations brought about by the existence of
are sufficiently pronounced to warrant speculations on the potential use of the chorus spectrograms as a diagnostic tool of geomagnetic‐field‐aligned electric fields, expected to occur, at least temporarily, beyond the plasmasphere.
Is UV laser induced fluorescence a method to monitor tropospheric OH?
Authors: Ortgies G. , Gericke K.‐H. , Comes F. J.
Published: February 2008

Calculations are presented which demonstrate the important interference of laser generated OH in ambient air with tropospheric OH if LIF technique is used. A comparison of previous measurements with the results of our calculations shows that the measured tropospheric OH concentration is within the order of magnitude of laser generated OH.
Ionospheric density enhancement during relativistic electron precipitation
Authors: Foster J. C. , Doupnik J. R. , Stiles G. S.
Published: February 2008

The temporal evolution of the ionospheric density enhancement produced by a widespread REP has been observed with the Chatanika Radar. The REP was associated with a substorm particle energization event, and both the ionospheric absorption and density perturbation exhibited a ∼90 min periodicity associated with the particles' longitudinal drift. A 80 keV characteristic energy for the precipitating electrons is deduced from ground‐based and satellite data. At the maximum of the event, electrons deposited ∼50 ergs/cm² sec in the ionosphere, producing a peak density of 5×105 cm−3 at 89 km altitude. At that time the radar observed densities greater than 105 cm−3 between 70 km and 110 km altitude and riometer absorption at 30 MHz was ∼12 db.
Spectrophotometry of IO: Preliminary Voyager 1 results
Authors: Soderblom L. , Johnson T. , Morrison D. , Danielson E. , Smith B. , Veverka J. , Cook A. , Sagan C. , Kupferman P. , Pieri D. , Mosher J. , Avis C. , Gradie J. , Clancy T.
Published: February 2008

Multispectral images of Io acquired with the Voyager 1 narrow‐angle camera agree with Earth‐based spectrophotometry to better than 10%. Although the surface materials have general spectral properties similar to various allotropes of sulfur, their ultraviolet (UV) reflectances are much higher. It is likely that varying amounts of SO2 frost mixed with or absorbed on sulfur‐rich materials raises the UV reflectance. The possible association with large amounts of SO2 with low temperature forms of sulfur in the white patches on Io is consistent with Io surface models in which SO2 and S exist in thermally stable stratified zones.
On the secular behavior of seasonal changes in ozone column density
Authors: Vernazza J. , Foukal P.
Published: February 2008

We have studied the daily Dobson measurements of ozone column made between 1957 and 1975. The ozone column density measured at the seasonal minima in the northern hemisphere, shows a clear increase over these years. The amount of increase is approximately 4‐5% between latitudes of 15N and 60N, and 11% in the data obtained between 60N and 90N. The seasonal maxima show no evidence for an increase during the same time period, in the northern hemisphere. We conclude that the secular increase of global ozone noted between approximately 1960 and 1970 by a number of authors, is caused by a physical mechanism that leads to an increase in the seasonal minima, while allowing the seasonal maxima to remain roughly constant.
Elevation changes near the San Gabriel Fault, southern California
Authors: Reilinger Robert
Published: February 2008

Analysis of repeated leveling observations in the vicinity of the San Gabriel fault in Southern California indicate subsidence immediately south of the fault relative to points to the north, south, and east. These observations were previously interpreted as reflecting tectonic motions associated with either the "Palmdale Bulge" or with preseismic effects of the San Fernando earthquake. Relative subsidence between 1953 and 1964 reaches approximately 9 cm and extends over a distance of more than 20 km. Subsidence occurs directly above the Saugus aquifer and shows a temporal correlation with the history of water level decline within the aquifer. The degree of subsidence of individual benchmarks is roughly proportional to the product of aquifer thickness and water level decline at the location of the benchmarks. These observations strongly suggest that movements of the surface near the San Gabriel Fault, previously inferred to be of tectonic origin, actually result from near surface sediment compaction within the Saugus basin.
On the charge state of the anomalous oxygen component
Authors: Klecker B. , Hovestadt D. , Gloeckler G. , Fan C. Y.
Published: February 2008

We report our observations of a phase lag between the intensity variations of high energy galactic cosmic rays and the quiet time oxygen flux in the energy region 7.6‐24 MeV/nucleon during the time period 1974‐1975. Phase lag or hysteresis effects have been observed during the 11‐year solar cycle for low energy galactic cosmic rays and several authors have shown that this hysteresis effect is a function of the velocity and rigidity (and therefore of the ionic charge) of the particles. Assuming a similar rigidity dependence of the phase lag during the transient intensity decrease of both galactic cosmic rays and the anomalous oxygen component in the time period 1974‐1975, and comparing the phase lag as observed for protons and helium during the same period with our oxygen measurements, we derive an upper limit of ∼4 for the ionic charge of the anomalous oxygen component.
Spatial correlation of large historical earthquakes and moderate shocks >10 km deep in eastern North America
Authors: Acharya Hemendra
Published: February 2008

A good spatial correlation is noted between historical earthquakes with epicentral intensity ≥VIII (MM) and recent moderate size earthquakes with focal depth >10 km, suggesting that large historical earthquakes in eastern North America may be associated with deep‐seated faults.
A theoretical assessment of the O3/H2O interference problem in the detection of natural levels of OH via laser induced fluorescence
Authors: Davis D. D. , Rodgers M. O. , Fischer S. D. , Heaps W. S.
Published: February 2008

Theoretical calculations are presented which estimate the possible magnitude of the O3/H2O derived OH interference signal resulting from the use of the laser‐induced fluorescence technique in measuring natural levels of tropospheric OH. Critical to this new assessment has been the measurement of the nascent OH quantum state distribution resulting from the reaction O(¹D) + H2O → 2OH, and an assessment of the subsequent rotational relaxation of the OH species when formed in high k levels.
Mass spectrometric detection of pre‐condensation nuclei in the stratosphere ‐ Evidence for a stratospheric gas to particle conversion mechanism
Authors: Arnold F. , Henschen G.
Published: February 2008

Electrically charged species having masses larger than 327 atomic mass units have been detected in the stratosphere by a newly designed balloon‐borne mass spectrometer. The particles appear to be arranged in a layer peaking around 30 km altitude where their abundance is at least comparable to that of “normal” ions. The peak has a very steep top and a less pronounced bottom. Arguments are put forward favoring an interpretation of the observed particles as charged “multi‐ion complexes”. A possible role of the newly detected particles in the physics and chemistry of stratospheric aerosols and trace gases is discussed.
Applications of the concept of generalized vorticity to space plasmas
Authors: Banks P. M. , Edwards W. F. , Rasmussen C. , Thompson R. C.
Published: February 2008

A reformulation of the momentum equation for electrons or ions in a collisionless plasma leads to an equation which describes the behavior of the plasma in terms of a generalized vorticity. This vorticity, which includes contributions from
and the magnetic field, is both divergence‐free and conserved along plasma flow streamlines. When the plasma has zero vorticity, a special relation is established; i.e.
. This result appears to have application to small scale magnetic features within both conventional space plasmas and superconductors.
The role of the inner boundary in models of focused interplanetary transport of solar particles
Authors: C. K. Ng , Kok‐Yong Wong
Published: February 2008

In models of focused interplanetary transport of solar particles, the presence and nature of the inner boundary may play an influential role, depending on the focusing strength of the interplanetary magnetic field. In an exponential magnetic field, when the inner boundary is located further in than physically reasonable, the artificial region between the injection point and the inner boundary acts as a reservoir, focusing the particles therein and retarding the escape of injected particles from the inner solar system.
H2 abundance in the atmosphere of Venus
Authors: Kumar Shailendra , Hunten Donald M. , Taylor Harry A.
Published: February 2008

The in situ measurements from the Pioneer Venus Orbiter (PVO) Ion Mass Spectrometer have led to the detection of H2+ ions in the Venus ionosphere. Although H2+ is a minor ion, its measurement provides the first direct clue for determining the H2 abundance in the upper atmosphere of Venus. A photochemical model using PVO measurements is used to derive an H2 mixing ratio of 10 ppm below 140 km altitude. The presence of this much H2 confirms our previous prediction that the reactions of O+ with H2 and subsequent recombination of OH+ provide an important source of nonthermal H observed in the Venus exosphere. The estimated escape flux for H is ∼108 cm−2 s−1
A model forming the transverse ranges of California by subduction of the Murray transform
Authors: Keller B.
Published: February 2008

The East Pacific Rise collided with western North America in the last 30 m.y. A model in which the preexisting transform geometry was preserved as the actively spreading ridge was subducted under the continent accounts for the gross features of tectonic geometry of the west coast including the mountain blocks and deep Neogene sediment basins of the Transverse Ranges. The present day geometry in this model has transform motion at the surface along the San Andreas Fault and parallel features with decoupling to the East along the old subduction interface.
A comparison of ozone measurements
Authors: Mauersberger K. , Finstad R. , Anderson S. , Robbins D.
Published: February 2008

A mass spectrometer beam experiment and a UV absorption instrument (modified Dasibi instrument) have simultaneously measured ozone mixing ratios in the stratosphere (20‐40 km). Both experiments were independently calibrated using absolute standards. The ozone profiles obtained during three balloon descents are in excellent agreement; fine structures are resolved by both experiments. The RMS uncertainty in ozone mixing ratios is about 3% for either instrument.
Concentration of carbon monoxide in the upper stratosphere
Authors: Zander R. , Leclercq H. , Kaplan L. D.
Published: February 2008

The concentration of telluric carbon monoxide has been determined in the upper stratosphere from infrared solar spectra recorded by balloon on October 1978 and September 1979, over Texas, USA. The average mixing ratios were found to be (2.1∓.3)×10−8ppv and (3.7∓.4)×10−8ppv above the float altitudes of 30.6 and 36.8 km, respectively. The concentration profile deduced from all our measurements indicates that the CO mixing ratio increases in the upper stratosphere, from (1∓.3)×10−8ppv at 30.6 km, to about 4×10−8ppv above 41 km.
Measurements of long delayed radio echoes in the auroral zone
Authors: Freyman Robert W.
Published: February 2008

A high‐latitude, earth‐based high‐frequency (9.9MHz) radiowave backscatter technique for the real‐time detection of Long Delayed Echoes was tested at College, Alaska. Over 2000 apparent LDE were detected and recorded from 15 to 22 July, 1980.

A positive correlation was obtained between the number of reflections per unit time and the probable entry of enhanced solar plasma into the magnetosphere and/or local disturbed magnetic conditions. The modes and paths by which the signals propagate are yet to be established. However, regardless of their origin, the echoes seem to be genuine and these observations are therefore unique in the study of LDE radiowave propagation phenomenology.
The production rate of C+ from the photoionization of CO and CO2
Authors: Samson James A. R. , Masuoka T. , Huntress W. T.
Published: February 2008

The dissociative photoionization cross sections for the production of C+ ions are presented for the spectral region from the dissociative ionization threshold to 90 Å. The cross sections are considerably larger than previously published data and should therefore influence the calculations of the C+ concentrations in the Mars and Venus ionospheres. It is suggested that the released energy in the C+ fragment ion could reduce the loss rate of the ions in collisional processes, thereby accounting for the apparent discrepancies between the observed and calculated C+ ion density in the Venus ionosphere.
Recent observations of HF and HCl in the upper stratosphere
Authors: Zander R.
Published: February 2008

Concentrations of gas phase hydrofluoric‐ and hydrochloric acid have been determined in the upper stratosphere from near‐infrared solar spectra recorded in the course of balloon fights from Palestine, Texas, USA (32°N latitude), in October 1978 and in September 1979. The average mixing ratios for HF deduced respectively from these flights are (4.8±.3)×10−10ppv above 30.3km and (6.2±.5)×10−10ppv above 36.8km. This observed difference is ascribed to an increase in the HF concentration out to at least 37km. The HCl mixing ratios deduced from the 1978 flight yield (4.5±.6)×10−10ppv at 21.7km, (7.5±.7)×10−10ppv at 27.5 km and (2.1±.4)×10−9ppv above 30.5km. Observations in 1979 imply an average HCl mixing ratio above 36.8km of (2.4±.4)×10−9ppv. Our data do not indicate a measurable temporal trend of the HCl concentration above 30km.
High‐pressure stability and thermodynamic properties of CoSiO3
Authors: Bohlen Steven R. , Boettcher A. L.
Published: February 2008

We determined the stability of CoSiO3 relative to Co2SiO4+SiO2 with reversed experiments in a piston‐cylinder apparatus. Our data at 1023, 1173, 1323, and 1473 K indicate instability of CoSiO3 below 17.2, 18.0, 19.1, and 20.4 Kbars. ΔG298° and ΔH298° (from oxides) calculated from our data between 900 and 1500 K are −12.5±0.2 kJ and −8.0±0.2 kJ, respectively. The dP/dT slopes of phase transformations in Fe‐bearing systems in planetary interiors that are inferred from Co analogues may be incorrect.
Potential for geochemical experiments in large scale tests
Authors: Vidale Rosemary
Published: February 2008

Geochemical problems that would benefit from large scale experiments include: 1) the determination of the physical properties of the many common rocks that are chemically homogeneous on the scale of 5‐100 cm but not on a scale of 1‐5 cm, 2) the study of the influence of rock textures and compositions and of the chemistry of the pore solution on stress corrosion cracking, and 3) the study of chemical transport within gradients in temperature, chemical potentials and stress. The ultimate goal of a few well‐chosen large scale studies should be the development of predictive models.
Experience with in situ measurement of rock deformability
Authors: Bieniawski Z. T.
Published: February 2008

Although in situ tests have the advantage of involving a large volume or rock tested under the same environmental conditions as are prevailing in the rock mass, such tests are expensive and time consuming. In addition, there are a number of controversial questions pertinent to in situ tests.

This presentation discusses the first‐hand experience with three in situ test methods. These are: (i) plate bearing tests, (ii) large and small flat jack tests, and (iii) Goodman jack tests. By identifying the problems associated with in situ testing, useful lessons can be learned for large scale laboratory testing in geomechanics.
Acquisition and preparation of specimens of rock for large‐scale testing
Authors: Watkins D. J.
Published: February 2008

The techniques used for acquisition and preparation of large specimens of rock for laboratory testing depend upon the location of the specimen, the type of rock and the equipment available at the sampling site. Examples are presented to illustrate sampling and preparation techniques used for two large cylindrical samples of granitic material, one pervasively fractured and one containing a single fracture.
Borehole studies of rock engineering problems in large scale laboratory equipment
Authors: Daemen Jaak J. K.
Published: February 2008

A testing facility which includes provisions for access to a co‐axial borehole in a cylindrical rock sample will provide the necessary means to study a number of engineering geomechanics problems that can not be investigated readily with presently available equipment. Examples include the stability of deep boreholes; the sealing performance of well cementing and plugging; the influence of size, shape, stress gradient and energy concentration effects on rock failure about underground openings (simulating deep shafts and tunnels in hard intact rock); influence of discontinuities and reinforcement on opening stability; ground‐interaction modeling of tunnel support mechanics. Approximate ranges for desirable loading conditions (axial and laterial rock stress, fluid pressure and flow, temperature, geochemical environment) are suggested for some of these problems as well as requirements for in‐hole instrumentation. A large scale laboratory testing facility will find immediate use for the study of many important rock engineering problems.
Hugoniot equation of state of periclase to 200 GPa
Authors: Vassiliou M. S. , Ahrens Thomas J.
Published: February 2008

New shock wave data on {100} oriented single crystal periclase covering the pressure range from 160 to 200 GPa suggest that MgO is described by a single Hugoniot up to 200 GPa, with no displacive phase transitions of volume change greater than 1‐1.5 per cent. For a third order finite strain fit, with KO constrained to its ultrasonically determined value of 162.7 GPa, the implied KO′ of 4.27 ± 0.24 is in agreement with ultrasonically determined value of 4.17 ± 0.14. The new data indicate a somewhat steeper Hugoniot than that suggested by previously published shock wave results under 120 GPa. A previously published result at 258 GPa shows more compression in the light of the present data than would be expected for MgO in the B1 structure, and may signal the onset of a phase transition, although we cannot confidently make this interpretation. If MgO forms an ideal solid solution with FeO, our data does not support the occurrence of a significant transition in magnesiowustite at lower mantle pressures.
Stratospheric sulfate from the Gareloi Eruption, 1980: Contribution to the "ambient" aerosol by a poorly documented volcanic eruption
Authors: Sedlacek W. A. , Mroz E. J. , Heiken G.
Published: February 2008

While sampling stratospheric aerosols during July‐August 1980 a plume of "fresh" volcanic debris was observed in the Northern hemisphere. The origin of this material seems to be a poorly documented explosive eruption of Gareloi volcano in the Aleutian Islands. The debris was sampled at an altitude of 19.2 km ‐ almost twice the height of observed eruption clouds. Such remote, unobserved or poorly documented eruptions may be a source that helps maintain the "ambient" stratospheric aerosol background.
The sunrise ozone depletion problem of the upper stratosphere
Authors: Aimedieu P. , Rigaud P. , Barat J.
Published: February 2008

The sunrise ozone depletion problem has been recently raised with regards to the stratospheric model validity question. The results of two morning flights at 42 km altitude which showed a 5% depletion of the ozone concentration during half hour following the break of the dawn are examined here. These measurements are discussed by comparison with those of several authors. Our measurements are consistent with all these results already published. This leads to the conclusion that the ozone concentration decreases at sunrise in the 40 km altitude range and up.
Effects of lithospheric rigidity on ocean floor bathymetry and heat flow
Authors: Jarvis Gary T. , Peltier W. R.
Published: February 2008

The observed quasi‐rigid behaviour of surface plates in the course of their relative motion is a consequence of the high viscosity which obtains in the cold near surface region. By assigning a particular constant velocity as the upper boundary condition in a numerical model of mantle convection, we have investigated the effect of lithospheric rigidity on the variation of oceanic bathymetry and heat flow as a function of ocean floor age. Predicted variations of both bathymetry and heat flow at the surface of mantle wide convection cells which are partially heated from within, exhibit the same qualitative behaviour as data compiled for the major ocean basins. The bathymetry varies with distance x from the spreading centre initially as x½ but subsequently flattens with respect to an x½ reference curve whereas the heat flow closely follows an x−½ decay over most of the convection cell. Consequently the viability of the mechanism for sea floor flattening proposed by Jarvis and Peltier (1980) is increased when a constant surface velocity, characteristic of rigid plates, is incorporated in the model. This model successfully predicts both that the bathymetry should flatten and that the heat flow should not.
Parting in giant garnets as an indicator of Late Brittle Deformation at Gore Mountain, Warren County, N.Y.
Authors: Valentino A. J. , Sclar C. B.
Published: February 2008

The Barton garnet deposit contains large garnet crystals (2.5 ‐ 25 cm) disseminated through a gabbro‐derived garnet amphibolite. These crystals are characterized by two sets of parting planes which intersect at about 80° and have a constant attitude throughout the amphibolite. The results of X‐ray diffraction studies on the parting planes of the garnet crystals by the back‐reflection Laue method and by X‐ray diffractometry show that the parting‐plane sets are not crystallographically controlled by the lattice of the garnet and that the garnets are not oriented in the amphibolite. Each parting set in the giant garnets and its corresponding parallel joint set in the amphibolite matrix are interpreted as brittle fractures which developed in response to a discrete tectonic episode.
A formula for calculating theoretical photoelectron fluxes resulting from the He+ 304 Å solar spectral line
Authors: Richards P. G. , Torr D. G.
Published: February 2008

We present a method for evaluating the ionospheric photoelectron fluxes resulting from the 304 Å solar radiation. This method can be used to verify the full theoretical calculation of these specific photoelectron fluxes. The formula may also be useful in monitoring variations in the 304 Å solar flux whenever direct solar flux measurements are unavailable. We have also performed photoelectron flux calculations using two different sets of inelastic electron collision cross sections. Fluxes obtained using an old set of cross sections are in good agreement with measured fluxes from Atmosphere Explorer‐E but are up to a factor of two larger at energies between 20 and 30 eV than fluxes from most other previously published theoretical calculations. However, spectra obtained with a newer larger set of collision cross sections are in agreement with the other theoretical models, but not with the measured spectra. This suggests that the disagreement between ionospheric photoelectron theory and experiment might be resolved by a review of the electron collision cross sections used in the theoretical models.
Extended positive ion composition measurements in the stratosphere ‐ Implications for neutral trace gases
Authors: Henschen G. , Arnold F.
Published: February 2008

The composition of stratospheric positive ions has been measured over an extended altitude range (24‐42 km) using balloon‐borne mass spectrometers. It was found that proton hydrate and non proton hydrate ions, mostly H+(X)L(H2O)M coexist throughout this region. The fractional abundance of non proton hydrate ions decreases somewhat with increasing height. Implications for the abundance of X, which probably is CH3CN are discussed.
Lidar observations of volcanic clouds in the stratosphere over Fukuoka, caused by eruptions of Mt. St. Helens in May 1980
Authors: Hirono M. , Fujiwara M. , Shibata T. , Kugumiya N.
Published: February 2008

A sudden increase of stratospheric aerosols has been observed by a Nd‐YAG lidar at the wavelengths 1.064 µm (F) and 0.532 µm (S) since June 4th, 1980 (all times JST = GMT +9). The increase is thought to be caused by the eruption of Mt. St. Helens in May, 1980. The initial increase began at an altitude of about 15km and the scattering ratio at wavelength F reached a maximum on June 5th. This indicates that the aerosol mixing ratio is about 70 times the non‐volcanic ratio at the same altitude. The extinction of the vertically incident direct solar radiation has been calculated to be 2 × 10−2 on the average for June and July, which is 4.6 and 3 times the non‐volcanic value, respectively, for the fall of 1979.

After examination of the size distribution of aerosols inferred from a comparison of profiles at the F and S wavelengths and data by other measurements, it may be concluded that our lidar has seen relative temporal and spatial variations of the aerosols fairly well, but underestimated their absolute magnitude due to the assumption of clean air near 30km. A method for correcting the underestimation would increase the extinction by a factor of 1.4 ‐ 2.0. This method is described and global distribution of aerosol inventory estimated on the basis of a two dimensional analysis.
Ground‐based microwave observations of mesospheric H2O in January, April, July, and September 1980
Authors: Thacker D. L. , Gibbins C. J. , Schwartz P. R. , Bevilacqua R. M.
Published: February 2008

The 616−523 rotational transition at 22.2 GHz has been used to measure the H2O vertical profile in the upper stratosphere and mesosphere. Observations were made during January, April, July, and September 1980 and, except in April, the average profile was characterized by a 10 ppmv layer between 60 and 70 km and a decrease in concentration to less than 1 ppmv above 80 km.
Trends of atmospheric methane in the southern hemisphere
Authors: Fraser P. J. , Khalil M. A. K. , Rasmussen R. A. , Crawford A. J.
Published: February 2008

Atmospheric observations spanning the past three years show that methane increased at 1.2 (±0.3)% per year at Cape Grim in Tasmania (41°S). This rate of increase can be compared to the 1.9 (±0.4)% per year observed at Cape Meares in Oregon (45°N) over the past two years. Over the corresponding period the concentration at Cape Grim increased by 1.4 (±0.4)% per year. The southern hemisphere data also suggest seasonal variations with minimum concentrations in March and maximum in September. These results are based on 26 large volume, stable air samples collected cryogenically in stainless steel flasks and 75 smaller volume air samples collected in glass flasks, all analyzed by a gas chromatograph using a flame ionization detector.
Juan De Fuca Plate – Aseismic subduction at 1.8 cm/yr
Authors: Acharya Hemendra
Published: February 2008

Volcanic activity in the Cascades in historic times suggests that the Juan De Fuca plate is underthrusting aseismically at about 1.8 cm/yr. This rate of underthrusting is identical to the rate computed from sediment studies.
On the vertical‐incidence VHF backscattered power profile from the stratosphere
Authors: Balsley B. B. , Gage K. S.
Published: February 2008

The slope of vertical incidence VHF backscattered power profiles from the stratosphere can be deduced from atmospheric stability profiles in conjunction with a recently‐developed model of backscattering from horizontally‐stratified refractivity structure in the clear air. The close resemblance of these theoretical profiles to profiles obtained from a number of different locations using the (MST) Doppler radar technique shows that vertical‐incidence VHF backscattering in the stratosphere arises from stable, horizontal laminae of radio refractive index that 1) have horizontal dimensions of many tens of meters, and 2) are distributed randomly throughout the stratosphere.
Multiply reflected standing Alfven waves in the IO torus: Pioneer 10 observations
Authors: Walker Raymond , Kivelson Margaret
Published: February 2008

Observations from the Voyager 1 pass by the Io flux tube strongly indicate that large amplitude standing Alfvén waves are generated as Jovian plasma flows past Io. Recently Gurnett and Goertz (1981) have proposed that this Io generated standing Alfvén wave system extends an appreciable way around the Io L‐shell. In this paper, we present observations of magnetic perturbations found in the Pioneer 10 record as it crossed the Io L‐shell. The field perturbations are qualitatively consistent with the passage of the spacecraft through a standing Alfvén wave pattern. The observations imply an Alfvén Mach number of 0.03, which is 1/5 of the value inferred from Voyager 1 observations. This implies a lower plasma density at the time of the Pioneer 10 flyby.
Altitude smearing due to instrumental resolution in MST radar measurements
Authors: Sato Toru , Fukao Shoichiro
Published: February 2008

Altitude smearing involved in MST radar measurements with low altitude resolutions is discussed, using the data obtained at Arecibo with an altitude resolution as high as 150 m. The smearing is of great concern in the case where the altitude resolution is as low as 3 km. The wind velocity deduced with the 3‐km resolution is biased from the true velocity where the wind shear is large. The bias of the order of 10 m/s persists for hours. Moreover, there appear spurious velocity fluctuations, which do not correspond to any of the fluctuating components in true velocity variation. Also, most of detailed layered structures detected with 150‐m altitude resolution are smeared out with 3‐km resolution. The present result strongly suggests that we should be careful enough in interpreting MST radar data obtained with altitude resolutions as low as 3 km.
Comments [on “Theoretical and experimental assessment of the O3/H2O interference problem…in the detection of OH…”]by Davis et al.
Authors: Wang Charles C. , Davis L. I.
Published: February 2008

This comment attempts to point out that the analysis of Davis et. al. on O3/H2O interference is in agreement with our published theoretical and experimental results, but their calibrations of OH measurements appear to be inconsistent. Possible resolution of this inconsistency is suggested.
On the three‐dimensional magnetic structure of the plasmoid created in the magnetotail at substorm onset
Authors: Hones E. W. , Birn J. , Bame S. J. , Paschmann G. , Russell C. T.
Published: February 2008

Reconnection of magnetic field lines at a neutral line that forms in the near‐earth region of the plasma sheet at substorm onset creates, from some longitudinal sector of the plasma sheet, a plasmoid that is then free to flow out of the magnetotail into the magnetosphere's wake. The magnetic field in the departing plasmoid frequently displays a strong positive or negative YSM component that has been difficult to reconcile with the reconnection geometry as it is traditionally depicted in two dimensions. We show that this deviation of the magnetic field is a manifestation of a draping of the newly reconnected field line loops toward the tail's central (midnight) meridian and that the draping is a consequence of the three‐dimensional plasma flow associated with the reconnection process.
Anomalous atmospheric spectral features between 300 and 310 nm interpreted in light of new ozone absorption coefficient measurements
Authors: McPeters Richard D. , Bass Arnold M.
Published: February 2008

Continuous scan data from the solar backscattered ultraviolet instrument on Nimbus 7, after known scattering and ozone absorption effects have been subtracted, reveals real structure in the atmospheric albedo between 300 and 310 nm, a region in which spectral anomalies have been reported in ground based observations. We find that these spectral anomalies are largely explained as structure at the one to five percent level in the ozone absorption coefficient as measured by Bass and Paur. Previous ozone absorption coefficient measurements were insufficiently accurate to resolve this structure.
Possible effect of the cloud electrification on the downdraft in thunderstorms
Authors: Kamra A. K.
Published: February 2008

Changes in the velocity of the raindrops due to electrical forces acting on them will change the drag force imparted by the drops to the air through which they are falling. These changes in the drag force have been argued to influence the initiation and development of the downdraft in thunderstorms. Changes in the development of balance levels and the effect of inclined electric fields have also been discussed in this context.
Verification of the crustal component in satellite magnetic data
Authors: von Frese R. R. B. , Hinze W. J. , Sexton J. L. , Braile L. W.
Published: February 2008

To investigate the utility of satellites for mapping crustal magnetic anomalies, POGO (Polar Orbiting Geophysical Observatory) and preliminary MAGSAT magnetometer data are compared with scalar aeromagnetic data obtained by the U.S. Naval Oceanographic Office (NOO)‐Vector Magnetic Survey of the conterminous U.S.A. POGO and available MAGSAT data demonstrate remarkable consistency over the study region. The NOO aeromagnetic data are low‐pass filtered for wavelengths larger than about 4° and spherically upward continued to 450 km elevation by equivalent point source inversion for direct comparison with POGO satellite magnetometer observations. The upward continued NOO data show that most of the energy is in the long wavelength ( ≅ 1000‐3000 km) anomalies. Removal of these wavelengths by suitable filtering reveals a residual anomaly field that corresponds well with the satellite anomalies, thus demonstrating that the satellite data are useful for mapping crustal magnetic anomalies. A number of correlations between the NOO, POGO and preliminary MAGSAT data are evident at satellite elevations, including a prominent transcontinental magnetic high which extends from the Anadarko Basin of the eastern Texas panhandle to the Cincinnati Arch. The transcontinental magnetic high is breached by negative anomalies located over the Rio Grande Rift and Mississippi River Aulacogen.
Application of dipole modeling to magnetic anomalies
Authors: Schmitz Dave , Frayser J. B. , Cain Joseph C.
Published: February 2008

A least‐squares technique is developed to obtain dipoles, which, when combined with an existing global field model, represent the relatively isolated magnetic anomalies which are residual to the high order (greater than 20) spherical harmonic internal geomagnetic field model. This combination of models (global spherical harmonic and local dipole) forms an efficient and compact representation of the geomagnetic field. The technique involves simultaneously solving for all three components of moment and of position of a dipole.

The technique is applied to the mega‐anomaly west of Australia in a region about Broken Ridge, using data and spherical harmonic models separately constructed from POGO and MAGSAT spacecraft. The resulting equivalent dipoles agree fairly well and may be averaged to a 1 T·km³ dipole buried at 60 to 70 km depth near 32°S, 97°E oriented horizontally with a small (3±3°) east declination.

This article contains supplementary material.
Sunward or anti‐sunward electric current in space below the MAGSAT level
Authors: Suzuki Akira , Fukushima Naoshi
Published: February 2008

The total electric current passing through the plane enclosed by the MAGSAT orbit can be calculated with a direct application of Maxwell's equation. A preliminary analysis of MAGSAT data for a very quiet day (November 5, 1979) shows that such a current amounts to 2·106 Amperes in its maximum intensity. The direction of current flow seems to vary; it was sunward around 0h and 9h UT, and anti‐sunward around 3h and 18h UT on that day. It is desirable to continue the analysis for the other days, in order to check whether or not the above tendency holds every day.
Evaluation of high latitude disturbances with MAGSAT (The importance of the MAGSAT geomagnetic field model)
Authors: Zanetti L. J. , Potemra T. A. , Sugiura M.
Published: February 2008

Studies of Birkeland current systems have been conducted primarily with low altitude satellite magnetometer data whereas electrojet current signatures have been usually analyzed with data from ground‐based magnetometer chains. However, the MAGSAT magnetometer data set allows magnetic disturbances due to both field‐aligned and electrojet currents to be examined simultaneously. This is mainly due to MAGSAT’s ∼400 km altitude, thus providing data closer to the electrojet current system than has been previously available from satellite measurements. Of additional importance are the superior accuracy, both in sensitivity and attitude, of the magnetic field measurements obtained by MAGSAT and last, but not least, the availability of an accurate magnetic field model of the concurrent epoch (based on the MAGSAT data set) that allows one to obtain a better baseline than previous models. The aforementioned points are emphasized and both Birkeland and electrojet currents have been analyzed in a case study for November 13, 1979.
A search for seamounts in the Southern Cook and Austral Region
Authors: Lambeck K. , Coleman R.
Published: February 2008

The existence of uncharted seamounts in the Cook‐Austral region of the South Pacific has been investigated using GEOS 3 and SEASAT radar altimeter observations. Three previously uncharted submarine seamounts, provisionally named GEOS A to GEOS C, have been located between Mauke and Rimatara and a fourth, GEOS D, has been located east of Rurutu. This confirms that the Aitutaki‐Mauke islands of the Southern Cooks are a continuation of the Austral chain. A second group of uncharted seamounts has been provisionally located some 200 km south of Rimatara and Maria and this is suggestive of a second seamount chain, south of the first, that includes Raratonga and Mangaia. Fabert Bank, to the south of Mangaia, appears to be mislocated by about 2° in longitude.
The spokes in Saturn's rings: A new approach
Authors: Carbary J. F. , Bythrow P. F. , Mitchell D. G.
Published: February 2008

We propose that zonal winds in Saturn’s atmosphere cause superrotation of the ionosphere and by virtue of field‐aligned currents generate a potential of ∼ 16 kV across the B‐ring. Such a potential can momentarily polarize ∼ 1‐10µm size ice particles in a radial sense and thus create the spectacular spokes. A resulting current flowing radially through the B‐ring would give rise to a power of ∼ 107 W, which is close to that dissipated in an SED burst.
Current carrying properties of double layers and low frequency auroral fluctuations
Authors: Singh Nagendra , Schunk R. W.
Published: February 2008

Numerical simulations showed recurring interruption and recovery of electron and ion currents through double layers. The time period τ of the recurring phenomena is governed by the ion dynamics; for ions with a drift Vi entering the simulation plasma such that Vi≲Vti, the ion thermal speed, τ is governed by the ion transit time from the location of ion injection to the location of the double layer. On the other hand, when Vi>Vti ion‐acoustic modes also appear in the electron‐ and ion‐current fluctuations. The electron current fluctuations are governed by the ion current through the Langmuir criterion. It is suggested that some low frequency auroral fluctuations could possibly be explained by current fluctuations through double layers.