bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of equatorial electron densities measured by whistlers and by a satellite radio technique
Authors: Carpenter D. L. , Anderson R. R. , Bell T. F. , Miller T. R.
Published: February 2008

For the first time, data on magnetospheric equatorial electron density from multiple whistler paths have been compared with in situ satellite measurements of electron density along near‐equatorial orbits. The whistler data were recorded at Siple, Antarctica (L ∼ 4.2) on June 28 and July 10, 1978, and at Palmer, Antarctica (L ∼ 2.3) on April 10, 1978. The satellite data were obtained by the University of Iowa Plasma Wave Experiment sweep frequency receiver (SFR) on ISEE‐1 during passes that remained within ∼±15° of the observing whistler station's longitude. The compared data are mostly in the range 3 < L < 5.2 and represent the nightside magnetosphere under calm to moderately disturbed magnetic conditions. The results show good agreement on density levels, and support the assumption that the electron density distribution along the high altitude part of field lines in the outer plasmasphere can be described by a diffusive‐equilibrium model. The data further suggest that the densities within the observed whistler ducts were within less than 30% of the mean or interduct level, and that over the L ranges of the comparisons, there were no significant east‐west density gradients within about ±15° of the whistler station's longitude.
Dissipation and turbulent heating of plasma in Jupiter’s magnetosphere
Authors: Barbosa D. D.
Published: February 2008

Voyager 1 observations of plasma waves in the dayside Jovian magnetosphere which show a correlation with measurements of localized concentrations of cool thermal plasma are presented. This moderately intense broadband electrostatic noise is shown to be of sufficient intensity to accelerate superthermal ions to energies ∼ 1 keV and higher. This process can account for the extensive heating of plasma in the magnetosphere and can energize a fraction of heavy ions to injection threshold for a high‐energy second stage acceleration mechanism. A brief discussion of the relation of this noise to Jovian magnetospheric dynamics is included.
40Ar/39Ar dating of terrestrial minerals with a continuous laser
Authors: York Derek , Hall Chris M. , Yanase Yotaro , Hanes John A. , Kenyon W. John
Published: February 2008

A new method of fusing samples for 40Ar/39Ar dating using a continuous argon‐ion laser is presented. Samples of hornblende, biotite, muscovite and slate were fused with a continuous laser and the results obtained agree with acres determined using our radio‐frequency (RF) fusion system. By varying the laser beam power level, it was possible to perform a step‐heating laser fusion of the slate which closely matched two RF step‐heating runs on the same material. Thus, not only does the continuous laser give an age‐microprobe capability, but it can routinely perform multi‐step heating experiments which are crucial to 40Ar/39Ar age interpretation.
A laboratory study of the dissociative excitation of the N+(5S) state
Authors: Erdman P. W. , Espy P. J. , Zipf E. C.
Published: February 2008

The prominent auroral emission feature near λ2145 Å has been tentatively identified as the N+ (5S) doublet lines [λ2139.68 Å and λ2143.55 Å]. Dissociative excitation of N2 by electron impact with a predicted cross section value ≥2 × 10−18 cm² has been proposed as the source of this metastable species. We have observed the N+ (5S) emission lines for the first time in a laboratory electron‐impact experiment and found that the cross section has a value of ∼ 3 × 10−21 cm² at 100 eV. This result eliminates dissociative excitation as a significant N+ (5S) source in auroras. Observation of the spatial distribution of the doublet radiation around the electron beam has provided some insights into the radiative lifetime of the 5S state, and we show that τr ∼ 5 µsec if the fragment ions are produced with a kinetic energy of ∼ 3 eV but ∼ 100 µsec if the N+ ions are formed with thermal energies.
Attenuation of wind waves by artificial surface films of different chemical structure
Authors: Hühnerfuss H. , Alpers W. , Lange P. A. , Walter W.
Published: February 2008

Experiments in a wind wave tunnel have shown that spectra of wind generated waves are modified by monomolecular surface films. Apart from the well known decrease of energy density two additional effects have been observed: a shift of the energy peak maximum and a dip in the short wavelength region of the gravity wave spectrum. Two mechanisms which would cause the shift of the peak maximum and one mechanism possibly contributing to the spectrum dip in the short gravity wave range are discussed.
Radio evidence for shock acceleration of electrons in the solar corona
Authors: Cane H. V. , Stone R. G. , Fainberg J. , Stewart R. T. , Steinberg J. L. , Hoang S.
Published: February 2008

A new class of kilometer wavelength solar radio bursts has been observed with the ISEE‐3 Radio Astronomy Experiment. These events resemble groups of ordinary type III bursts but have some unique properties. They are very intense and have durations considerably longer than groups of type III bursts. The new class of events do not necessarily occur at the times of reported meter wavelength type III activity and therefore do not appear to be the continuation of such activity to long wavelengths. Instead they occur at the reported times of type II events, which are indicative of a shock wave. An examination of records from the Culgoora Radio Observatory shows that the associated type II bursts have fast drift elements emanating from them i.e. herringbone structure. It is proposed that the new class of bursts are the long wavelength continuation of herringbone structure and it seems probable that the electrons producing the radio emission are accelerated by shocks. The new type of events will be referred to as shock accelerated (SA) events. The characteristics of SA events are discussed.
Static fatigue of granite at 200°C
Authors: Kranz Robert L. , Harris William J. , Carter Neville L.
Published: February 2008

Cylinders of Barre and Westerly granites have been compressed to failure in static fatigue tests under dry and wet conditions at 1 Kb confining pressure and temperatures of 24° and 200°C. The effect of increasing temperature and water content is, as expected, to weaken the rocks appreciably and to reduce the time to failure, at constant stress, by about two orders of magnitude. The activation energy estimated for dry Barre granite deformed in the temperature range 24° to 200°C is 10.2 Kcal/mol which seems reasonable and is consistent with other work at higher temperatures. Extrapolation of the static fatique equations obtained for specimens deformed at 200°C, both wet and dry, to 108 years yields maximum stress differences near 3 Kb. While such extrapolations may be reasonable for intact material over time‐spans of interest to national concerns, the stresses obtained seem unreasonably high for tectonic deformations. The discrepancy probably results from the very short durations of the tests which do not permit effective operation, at these low temperatures, of the several thermally‐activated weakening effects of H2O on silicates.
In‐situ evidence for a low degree of S‐wave anisotropy in the oceanic upper mantle
Authors: Clowes Ron M. , Au Daniel
Published: February 2008

A seismic refraction survey using ocean bottom seismometers with one vertical and two horizontal component geophones was carried out off western Canada. This report presents one feature of a comprehensive interpretation of the data set, that dealing with shear‐wave velocity anisotropy in the uppermost mantle. Amplitude‐and traveltime‐corrected SV record sections for two profiles, EX2 approximately parallel to the spreading ridge and EX3 approximately parallel to the direction of spreading, were compiled. From an interpretation based on comparisons with synthetic seismograms, the shear wave velocity in the upper mantle is 4.5 km/s for EX2 and 4.6 km/s for EX3. The corresponding compressional wave velocities are 8.3 km/s and 7.5 km/s. The significant difference in P‐wave velocities is attributed to azimuthal velocity anisotropy of the type normally found in the Pacific basin. In contrast, the small difference in S‐wave velocities suggests a very low degree of shear wave anisotropy. The combination gives a prominent anisotropy in values of Poisson's ratio for the upper mantle, the first in‐situ evidence for this feature. These results are consistent with laboratory measurements on ultramafic rock samples from ophiolite complexes.
Mean meridional winds in the mid‐ and high‐latitude summer mesosphere
Authors: Nastrom G. D. , Balsley B. B. , Carter D. A.
Published: February 2008

We examine the mean meridional flow in the summer upper mesosphere using data from the Poker Flat MST radar and all other available stations. The observed mean flow is equatorward at about 10‐15 ms−1 near 60°N, about an order of magnitude larger than expected from numerical model results. The Rayleigh friction coefficient required to balance the coriolis torque associated with this flow is about 4 days−1, about ten times larger than values currently used in numerical models.
Ionospheric electron content depletions associated with amplitude scintillations in the equatorial region
Authors: DasGupta A. , Aarons J. , Klobuchar J. A. , Basu Santimay , Bushby A.
Published: February 2008

The diurnal and seasonal behavior of the depletions in the ionospheric electron content, associated with amplitude scintillations measured at Arequipa, Peru for about one year around the recent solar maximum period, are presented. The seasonal variation shows asymmetrical equinoctial maxima, the February‐April period having markedly higher occurrences. Amplitude scintillation measurements at 1.54 GHz and 257 MHz at the nearby magnetic equatorial station Huancayo, Peru also show a similar pattern. A comparison of the three sets of data indicates the simultaneous development of irregularities of different scale sizes and earlier erosion of the smaller scale irregularities.
Evidence for solar magnetic loops beyond 1 Au
Authors: Sarris E. T. , Krimigis S. M.
Published: February 2008

In this work, we present observations of energetic particles injected by solar flarges into extended solar magnetic looplike structures. From the development of the angular distributions of the intensities of energetic protons (Ep ≥ 300 keV, Ep ≥ 25 MeV) and electrons (Ee ≥ 220 keV), we have inferred that energetic particles are bouncing between two magnetic mirrors and have obtained for the first time estimates of the extent of magnetic loops to distances ∼ 3.5 AU from the sun.
A problem in representing the core magnetic field of the Earth using spherical harmonics
Authors: Carle H. M. , Harrison C. G. A.
Published: February 2008

It is customary to represent the magnetic field of the Earth by a series of spherical harmonic coefficients of the magnetic potential up to a certain degree and order, usually about thirteen. Although this has certain computational advantages, such as upward and downward continuation, we show that there are also serious disadvantages. For instance, the use of spherical harmonics up to a certain degree does not remove from the surface fields all wavelengths greater than a certain value. This can be shown both theoretically and using observations. It is also shown that the total field magnitudes represented by spherical harmonics up to a certain degree have minimum wavelengths equal to the circumference of the Earth divided by twice the maximum degree of harmonic used. We discuss briefly the implications concerning how surface fields are separated into core and crustal components.
Spatial resolution and repeatability of MAGSAT crustal anomaly data over the Indian Ocean
Authors: Sailor R. V. , Lazarewicz A. R. , Brammer R. F.
Published: February 2008

Preliminary results from analysis of individual MAGSAT tracks in the eastern Indian Ocean demonstrate the resolution capability and repeatability of these data. Spectrum analysis indicates that 250 km is the absolute lower limit for resolving crustal magnetic anomalies in Magsat along‐track data. Spectral coherence analysis of closely‐spaced tracks shows that magnetic anomaly features with wavelengths greater than 700 km are highly repeatable from track to track.
Preliminary correlations of MAGSAT anomalies with tectonic features of Africa
Authors: Hastings David A.
Published: February 2008

An overview of the MAGSAT scalar anomaly map for Africa has suggested a correlation of MAGSAT anomalies with major crustal blocks of uplift or depression and different degrees of regional metamorphism. The strongest MAGSAT anomalies in Africa are closely correlated spatially with major tectonic features. Although a magnetic anomaly caused by a rectangular crustal block would be offset from the block's center by the effects of magnetic inclination, an anomaly caused by real crustal blocks of varying uplift, depression, and degree of regional metamorphism would be located nearer to the locus of greatest vertical movement and highest grade of metamorphism. Thus, the Bangui anomaly may be caused by a central old Precambrian shield, flanked to the north and south by two relatively young sedimentary basins.
A mechanical model of precursory source processes for some large earthquakes
Authors: Dmowska Renata , Li Victor C.
Published: February 2008

A mechanical model is presented of precursory source processes for some large earthquakes along plate boundaries. It is assumed that the pre‐seismic period consists of the upward progression of a zone of slip from lower portions of the lithosphere towards the Earth's surface. The slip front is blocked by local asperities of different size and strength; these asperities may be zones of real alteration of inherent strength, or instead may be zones which are currently stronger due to a local slowdown of a basically rate‐dependent frictional response. Such blocking by a single, large asperity, or array of asperities, produces quiescence over a segment of plate boundary, until gradual increase of the stress concentration forces the slip zone through the blocked region at one end of the gap, thus nucleating a seismic rupture that propagates upwards and towards the other end. This model is proposed to explain certain distinctive seismicity patterns that have been observed before large earthquakes, notably quiescence over the gap zone followed by clustering at its ends prior to the main event. A discussion of mechanical factors influencing the process is presented and some introductory modelling, performed with the use of a generalized Elsasser model for lithospheric plates and the "line spring" model for part‐through flaws (slip zones) at plate boundaries, is outlined briefly.
Comet‐like interaction of Venus with the solar wind III the atomic oxygen corona
Authors: Wallis Max K.
Published: February 2008

Suprathermal atomic oxygen constituting an extensive exospheric corona give rise to new heavy ions within the solar plasma flowing around Venus. Because their gyro‐radii are large compared with transverse scales, the O+ ions do not simply effect a drag due to ‘mass loading’ of the flow. Some precipitate into the ionosphere and provide a novel ion source. Also, the back‐reaction on the flow not only decelerates it, but also deviates it laterally and essentially asymmetrically about the planet.
Seasonal variation in the occurrence time of the equatorial midnight temperature bulge
Authors: Bamgboye D. K. , McClure J. P.
Published: February 2008

We have reexamined incoherent scatter radar data on electron and ion temperature from the Jicamarca Radar Observatory (12°S, 77°W; 1°N diplat) for the period 1967‐68 and early 1969. We find clear evidence of systematic nighttime temperature increases presumably associated with the “midnight pressure bulge” and the collapse of the middle latitude F region. A significant new finding is that the temperature enhancements tend on the average to occur about two hours before midnight in the local summer and about one hour after midnight in the local winter. The bulges appear in various shapes and the enhancement magnitudes vary considerably from barely detectable to many tens of degrees Kelvin, but show a definite tendency to be smaller in winter than in summer, when increases of up to 200 K are sometimes observed. Changeover from “summer” to “winter” behavior occurs within two months or less around equinox. Our results are consistent with the hypothesis of a nighttime equatorial temperature bulge moving with the antisolar meridian, but, at Jicamarca, systematically centered ∼ 30° west of this meridian ( ∼ 2 hrs before midnight) near the December solstice and ∼ 15° east of it near the June solstice. Our data have relevance to the questions of seasonal changes in the phase and amplitude of the tidal modes responsible for the midnight pressure and temperature bulge.
Solar irradiance in the stratosphere: Implications for the Herzberg continuum absorption of O2
Authors: Frederick J. E. , Mentall J. E.
Published: February 2008

The third Solar Absorption Balloon Experiment performed measurements of the attenuated solar irradiance between 200 and 210 nm as the payload ascended from 32 to 39 km. Comparison of these data with calculations based on ozone and pressure measurements made from the payload shows more solar radiation reaching the middle stratosphere than is predicted by O2 and O3 cross sections which are widely used in photochemical modeling. Consideration of the uncertainties in the balloon data and laboratory experiments indicates that the discrepancy can best be removed by adopting Herzberg continuum cross sections for O2 which are equal to or slightly less than the smallest values which have appeared in the literature.
A stratospheric aerosol increase during 1981, observed by Lidar over mid‐Europe
Authors: Reiter R. , Jäger H. , Carnuth W. , Funk W.
Published: February 2008

After the middle of May 1981 lidar observations at Garmisch‐Partenkirchen recorded a marked enhancement of the aerosol backscattering from the lower stratosphere. Until the end of July several distinct aerosol layers could be detected which thereafter merged into a broad homogeneous layer. The eruption of volcano Alaid, Kurile Islands, on 28 April is suggested as the source of this recent stratospheric aerosol increase. This aerosol disturbance is of about the same magnitude as that caused by Mount St. Helens in May 1980. Significant climatic effects are not predicted.
A composite focal mechanism for microearthquakes along the northeastern border of the Caribbean Plate
Authors: Frankel Arthur
Published: February 2008

Seismograms from a local seismic network in the Virgin Islands portion of the northeastern Caribbean are used to determine a composite focal mechanism for 26 microearthquakes along the North America ‐ Caribbean plate boundary. Only one nodal plane of the focal mechanism could be constrained from P‐wave first motion data alone. P/SV amplitude ratios observed for these events were compared to theoretical amplitude ratios calculated for different focal mechanisms. This procedure constrained the dip of the second nodal plane to be shallower than about 50°, ruling out the possibility of a transform fault in this portion of the plate boundary. The resulting focal mechanism indicates that oblique underthrusting of the North American plate beneath the Caribbean plate occurs in the area. This oblique motion is accommodated along a thrust plane that dips at a relatively shallow angle beneath the Virgin Islands platform.
Rocket observation of the NII 2143A dayglow
Authors: Barth Charles A. , Steele Robert E.
Published: February 2008

The NII 2143A doublet has been observed in the earth's dayglow with a rocket spectrometer at an altitude of 200 km. The slant column emission rate of this airglow is 333±67 Rayleighs at a zenith angle of 87.6°. The likely excitation mechanisms are photoionization of molecular nitrogen by solar extreme ultraviolet radiation and photoelectron impact excitation of molecular nitrogen.
Measurements of the aerosol and ice crystal populations in tropical stratospheric cumulonimbus anvils
Authors: Knollenberg R. G. , Dascher A. J. , Huffman D.
Published: February 2008

A pair of particle size spectrometers was flown aboard the NASA U‐2 operating from the Canal Zone to make measurements of the aerosol and ice crystal budgets in cirrus produced by thunderstorms in the tropics. Measurements indicate that fairly large crystals up to 1 mm in size are injected into the stratosphere during cumulonimbus activity. Ice water contents range from a few thousandths to a few hundredths of a gram per cubic meter. Because the ambient temperature is typically around −80°C the mass of the larger crystals largely returns to lower altitudes before evaporating. Aerosol size distributions indicate a curious narrow growth mode between 0.15 and 0.2 µm in cirrus anvils which is absent outside these clouds. The presence of this narrow mode is attributed to near water saturation produced at cloud top. Nucleation of new ice crystals as well as aerosol is hypothesized.
The analysis of variance of an underdetermined geodetic displacement problem
Authors: Darby Desmond
Published: February 2008

It has been suggested recently that point displacements in a free geodetic network traversing a strike‐slip fault may be estimated from repeated surveys by minimizing only those displacement components normal to the strike. It is desirable to justify this procedure. We construct, from estimable quantities, a deformation parameter which is an F‐statistic of the type occurring in the analysis of variance of linear models not of full rank. A test of its significance provides the criterion to justify the displacement solution. It is also interesting to study its behaviour as one varies the supposed strike of the fault. Justification of a displacement solution using data from a strike‐slip fault is found, but not for data from a rift valley. The technique can be generalized to more complex patterns of deformation such as those expected near the end‐zone of a fault in a dislocation model.
Loss of oxygen from Venus
Authors: EcElroy M. B. , Prather M. J. , Rodriguez J. M.
Published: February 2008

Ionization of thermal and non‐thermal oxygen atoms above the plasmapause on Venus supplies an escape flux for O averaging 6 × 106 atoms cm ²sec−1. Hydrogen and oxygen atoms escape with stoichiometry characteristic of water. It is argued that escape of H is controlled by the oxidation state of the atmosphere, regulated by escape of O.
The spectrum of the Jovian aurora 1150–1700 Å
Authors: Durrance Samuel T. , Feldman Paul D. , Moos H. Warren
Published: February 2008

A series of observations of the northern hemisphere of Jupiter was made in January 1981 using the International Ultraviolet Explorer short‐wavelength spectrograph. Exposures of 15 minutes each were made at regular intervals of about 45 minutes around the time when Jupiter's north magnetic pole was tilted toward the Earth. The auroral emissions of H Lyman‐α, and the H2 Lyman‐ and Werner‐bands are seen to emanate from a localized region near the north pole. Their intensity increases and decreases in a periodic way as the planet rotates with the maximum occuring at λ III ∼185°. Using the three observations nearest the observed maximum, a composite spectrum of the aurora is obtained with about 8 Å resolution and high signal‐to‐noise ratio, and many of the H2 Lyman‐ and Werner‐bands in this spectral region (1150–1700 Å) are identified. This spectrum is compared with a laboratory H2 spectrum and with photoabsorption cross sections for CH4 and C2H6. An upper limit to the slant column density of these hydrocarbons above the auroral emissions is found to be ∼ 2×1017 cm−2.
The atmospheric lifetimes of CFC 11 and CFC 12
Authors: Owens A. J. , Steed J. M. , Miller C. , Filkin D. L. , Jesson J. P.
Published: February 2008

A two‐dimensional (2‐D) chemical model of the atmosphere is used to investigate the stratospheric removal rates of the Chlorofluorocarbons CFC 11 (CFCl3) and CFC 12 (CF2Cl2). Assuming equivalent vertical transport rates, one‐dimensional (1‐D) models are shown to overestimate the atmospheric lifetime of CFC 11 by ∼10% because of their neglect of latitudinal effects. The present Du Pont 1‐D and 2‐D models have somewhat different effective transport rates and give steady state CFC 11 atmospheric lifetimes of 75 and 60 years, respectively, assuming no tropospheric destruction mechanism. For CFC 12, the corresponding calculated lifetimes are 140 and 120 years.
Fabry‐Perot interferometer measurements of thermospheric neutral wind gradients and reversals at Arecibo
Authors: Friedman J. F. , Herrero F. A.
Published: February 2008

Direct measurements of the meridional neutral winds in the thermosphere with the Arecibo Observatory Fabry‐Perot Interferometer show the post‐midnight meridional wind reversal that was inferred from previous incoherent scatter radar ion‐drift data and airglow intensity maps, and observed in‐situ with the Atmosphere Explorer‐E satellite NATE experiment. Data are shown for three nights between October 29 and December 9, 1981. For this period, the meridional wind is observed to be northward after sunset, turning southward before midnight with velocities which often exceed 100 m/sec, and after midnight its direction reverses to northward for one to two hours. The post‐midnight reversal is recurrent, and propagates from the equator, as predicted ort the basis of previous meridional airglow intensity measurements. On some nights the reversal is observed only to the south of Arecibo. In those cases it is possible to measure the wind velocity gradient which is set up by the convergent flow. The night of 29/30 October 1981 shows a gradient of about (0.3m/s)/km associated with the reversal (00‐0100 LT). Two hours later (0300 LT) an equatorward propagating disturbance with speed of propagation of about 700 m/s is observed. The gradients associated with the disturbance and with the reversal are of the same order of magnitude, giving changes of more than 150 m/sec in a horizontal distance of 500 km. The velocity gradient changes direction as a consequence of the passage of the disturbance. The simultaneous meridional airglow intensity distributions follow the direction of the velocity gradient.
A discrepancy between long‐ and short‐period mechanisms of earthquakes near the Long Valley Caldera
Authors: Wallace Terry , Given Jeff , Kanamori Hiroo
Published: February 2008

The largest events in the 1980 Mammoth Lakes earthquake sequence show a discrepancy between fault mechanisms which are determined on the basis of the local short‐period first motions and those determined by modeling of long‐period regional and teleseismic waveforms. The short‐period solutions are left‐lateral strike‐slip on north‐striking, near vertical planes. The long‐periods invariably require a much more moderately dipping fault plane with a significant dip‐slip (normal) component. Persistence of disagreements between short‐ and long‐period polarities to teleseismic distances suggests that the source‐time functions are complicated and may be responsible for at least part of the discrepancy. In addition, there seems to be a systematic difference between local short‐period polarities and teleseismic long‐period polarities that is related to travel paths across portions of Long Valley Caldera. It is possible that a low velocity zone related to recent magmatic activity is causing the deflection of local seismic rays, thus distorting the fault plane projection.
the two‐component auroral electrojet
Authors: Kamide Y.
Published: February 2008

By using the AL index for one year as well as some of the IMS meridian chain records, the longitudinal center of the substorm westward electrojet is examined. Although on the average AL is most often dominated by stations located near 0300 MLT, the westward electrojet during the expansion and maximum phase of substorms tends to be centered in the premidnight to early morning sector, and, during the recovery phase, it is most intense in morning hours. It is suggested that the substorm‐associated westward electrojet consists of two components which have different characteristic times; one produced mainly by Hall conductivity enhancements which dominate in the midnight sector and the other one by southward electric fields in the morning sector.
Terrestrial continuum radiation observations with GEOS‐1 and ISEE‐1
Authors: Etcheto J. , Christiansen P. J. , Gough M. P. , Trotignon J. G.
Published: February 2008

Examples of results from a dual satellite (GEOS‐1 and ISEE‐1) study of terrestrial non‐thermal electromagnetic continuum radiation are presented. The problems of sources and generation mechanisms are discussed in the context of simultaneous measurements of radiation arrival directions, radiation cut‐offs, and detailed spectral observations. The results, which imply significant contributions from the magnetospheric volume to the low frequency (‘trapped’) component, confirm the near‐plasmapause as the source of the higher frequency (‘escaping’) component. The detection of significant X mode radiation and the implied presence of localized non‐directive sources lead us to conclude that current theories of generation are inadequate.
Lidar observations of dust layers' transience in the stratosphere following the El Chichon volcanic eruption
Authors: D'Altorio Alfonso , Visconti Guido
Published: February 2008

Intense stratospheric dust layers have been observed with a lidar at L'Aquila (42°N, 13°E) during the months of July and August 1982. These features were located at 22‐26Km with a maximum scattering ratio of 13. In one occasion a layer was also observed at 32Km. Maximum integrated scattering is of the order of 0.001 sr−1. The almost daily frequency of the observations has revealed an unusually fast decrease of the altitude of the layers with an apparent velocity of 0.2‐0.3Km/day. This pattern is repeated in both the high altitude layers observed. It is speculated that this effect could be attributed to the zonal distribution of the dust which in turn could depends on dust formation process.
First infrared measurement of atmospheric NO2 from the ground
Authors: Camy‐Peyret C. , Flaud J.‐M. , Laurent J. , Stokes G. M.
Published: February 2008

High resolution Fourier transform spectra of the atmosphere in the 2850 ‐ 2950 cm−1 region have been recorded from the ground using the sun as a source. For the first time, many NO2 absorption peaks belonging to the ν1 + ν3 band and its associated hot band ν1 + ν2 + ν3 − ν2 have been located. Among them, 13 well isolated features have been used to determine NO2 vertical column densities. Indeed, from the analysis of 4 spectra recorded at air masses of 10.7, 5.4, 3.1 and 10.8, that is for the 3 first ones just after sunrise and in the early morning and for the last one just before sunset, vertical column densities of 1.84 ± 0.34, 1.80 ± 0.28, 1.74 ± 0.44 and 3.24 ± 0.46 1015 molecule.cm−2 have been obtained. The good absolute accuracy of these results is due to the use of several lines having a wide enough range of intensities and of lower state energy levels.
Tidal‐current channeling in the San Andreas Fault, California
Authors: Johnston M. J. S. , Ware R. H. , Mueller R.
Published: February 2008

Measurements of magnetic fields along the San Andreas fault indicate that inhomogeneous tidally generated current systems flow in and around the fault system. These currents limit measurements of short‐term local fields of tectonomagnetic origin to about 0.3 nT but can be easily removed. Ocean‐tidal induction into a complex fault zone with higher than average electrical conductivity appears to be a more likely explanation than either piezomagnetic effects due to solid‐earth tides or ionospheric‐tidal induction. The amplitudes of the induced diurnal harmonics decrease fairly linearly to the southeast along the fault. This result is consistent with expectations from a hotter and more conductive crust and upper mantle in southern California, as indicated by heat‐flow data for this region.
Observations of optical emissions on STS‐4
Authors: Mende S. B. , Garriott O. K. , Banks P. M.
Published: February 2008

Following the discovery of intense vehicle glow of the space shuttle on the STS‐3 mission, a new experiment to probe this phenomenon was developed and flown on the shuttle STS‐4 mission. A conventional camera was equipped with an objective transmission grating and several photographic exposures were taken of the shuttle tail from the aft flight deck window. Vehicle glow surrounding shuttle surfaces exposed to the ram direction was observed on a long (400 second) exposure. From analysis of the resulting spectral data it appears that the shuttle glow has a diffuse spectral component in the region 6300 to 8000A. In addition, it has been possible to assess the spectral character of light emitted by the firing of a reaction control system thruster. Our data show that the light emitted from the thruster gases is confined to wavelengths shorter than 7200A.
A feldspar‐liquid geothermometer
Authors: Smith Michael P.
Published: February 2008

An expression that can be used to accurately calculate one atmosphere equilibration temperatures from the compositions of coexisting feldspars and liquids was derived from experimentally studied natural systems and a wide range of simple systems. This expression is a superior predictor of temperature compared to other feldspar‐liquid geothermometers.
Three dimensional velocity image of a barrier associated with a moderate Pyrenean Earthquake
Authors: Grasso Jean Robert
Published: February 2008

The prominent role of barriers is now well recognized in both the initialization and the extension of the earthquake rupture. The mapping of barriers is therefore important in understanding the physical processes by which earthquakes occur. We invert 800 P wave travel times from an aftershock sequence following a moderate earthquake (mb = 5.1) in the Pyrenean area (France) using a stochastic inverse technique to derive a three‐dimensional velocity image of the structure. We have carried out two scales of imagery. Both scales reveal the presence of a high velocity contrast (+ 8 %) at the eastern limit of the aftershock zone. This velocity anomaly corresponds to a geometric discontinuity in the trace of the major fault and can be mapped down to a depth of 8 km. This article contains supplementary material.
Ozone densities in the lower mesosphere measured by a limb scanning ultraviolet spectrometer
Authors: Rusch D. W. , Mount G. H. , Barth C. A. , Rottman G. J. , Thomas R. J. , Thomas G. E. , Sanders R. W. , Lawrence G. M. , Eckman R. S.
Published: February 2008

The ozone content of the earth's atmosphere between 1 mb and 0.08 mb has been measured as a function of latitude and season by an ultraviolet spectrometer on the Solar Mesosphere Explorer spacecraft. The ozone mixing ratio is found to be highly variable in time and space during the winter of 1982 with maxima occuring in the winter hemisphere during January and February at all pressure levels. The latitude gradients near spring equinox are relatively small. A relative maximum occurs at latitudes between 15 and 30°S in January and February.
Mesospheric ozone depletion during the Solar Proton Event of July 13, 1982 Part I Measurement
Authors: Thomas R. J. , Barth C. A. , Rottman G. J. , Rusch D. W. , Mount G. H. , Lawrence G. M. , Sanders R. W. , Thomas G. E. , Clemens L. E.
Published: February 2008

The near infrared spectrometer and the ultraviolet spectrometer on the Solar Mesosphere Explorer (SME) observed the ozone density as a function of latitude and altitude during the solar proton event of July 13, 1982. Airglow at 1.27 µm was observed at the earth's limb. The altitude profiles of the emission were inverted providing ozone densities. The ozone densities observed showed a clear decrease during the event. The maximum depletion seen was 70%. The decrease was observed in the northern high latitudes at mesospheric altitudes. The decrease was very short lived, lasting less than a day.
Lidar observations of the El Chichón dust cloud at 23°S
Authors: Clemesha B. R. , Simonich D. M.
Published: February 2008

Lidar observations of the stratospheric aerosol scattering at São José dos Campos (23°S, 46°W) show a very large increase in the stratospheric aerosol burden to have occurred in mid‐1982. Peak scattering ratios greater than 5 have been observed, as compared with pre‐enhancement values between 1.1 and 1.2, representing an increase by more than an order of magnitude in particulate scattering. It is concluded that the main source of the dust was the eruption of El Chichón in Mexico in late March and early April of 1982.
High medieval auroral incidence over China and Japan: Implications for the medieval site of the geomagnetic pole
Authors: Siscoe George L. , Verosub Kenneth L.
Published: February 2008

The catalog of historical oriental aurorae compiled by Keimatsu lists 116 aurorae from China and 31 aurorae from Japan in the period 801 to 1400 AD. The two listings have no events in common. If they are considered as independent random samples from the same population, the lack of overlapping events can be used to determine the probabilities of different medieval auroral occurrence frequencies over the China‐Japan quarter. We find that there is a 95 percent probability that the average rate exceeded the inferred present rate by more than a factor of 20. This corresponds to a geomagnetic pole located in the Eastern Hemisphere displaced more than 9 degrees from the geographic pole.
Magnetic fields in the ionospheric holes of Venus: Evidence for an intrinsic field?
Authors: Luhmann J. G. , Russell C. T.
Published: February 2008

The suggestion that the radial magnetic fields observed in the regions of depleted plasma density in the nightside Venus ionosphere arise from an intrinsic planetary field was recently made by Knudsen et al. (1982). In this report the polarities of these radial fields, as measured by the Pioneer Venus Orbiter magnetometer, are examined in detail in order to determine if there is a geographical organization of the field polarity, or if the polarity of the radial field depends on the interplanetary field as previously proposed. The results of the data analysis indicate that a source in a planetary intrinsic field is unlikely.
Relation of summit deformation to East Rift Zone eruptions on Kilauea Volcano, Hawaii
Authors: Epp David , Decker Robert W. , Okamura Arnold T.
Published: February 2008

An inverse relationship exists between the summit deflation of Kilauea, as recorded by summit tilt, and the elevation of associated eruptive vents on the East Rift Zone. This relationship implies that East Rift eruptions drain the summit magma reservoir to pressure levels that are dependent on the elevation of the eruptive vents.
Shape of the magnetosphere
Authors: Wu C. C.
Published: February 2008

The shape of the magnetosphere has been studied by using a global MHD model of the magnetosphere. It is found that MHD and the Chapman‐Ferraro models agree in total magnetopause current distributions, but that the MHD model presents a very different physical picture from that of the Chapman‐Ferraro model. In the MHD model with BIMF = 0 or northward, the cusp is not exposed directly to the solar wind because the dayside magnetic field lines drape around the nightside magnetosphere. Furthermore, in the MHD model a current sheet exists above the cusp region.
Evidence for correlation of ultrasonic attenuation and fluid permeability in very low porosity water‐saturated rocks
Authors: Berryman J. G. , Bonner B. P. , Chin R. C. Y.
Published: February 2008

The measured amplitude A of ultrasonic pulses in intact and fractured samples of water‐saturated gabbro and granite is observed to decrease as the permeability κ increases according to the proportionality A ⧜ κ−1/2. This relation is predicted by Biot's theory of elastic waves in fluid‐saturated porous media and, therefore, suggests that Biot's attenuation mechanism may play a significant role in low porosity materials at ultrasonic frequencies. The evidence is not conclusive. The limited data set studied here is also consistent with correlations of the form A ⧜ κ−ε where 0.2 < ε < 0.6. Nevertheless, the observed correlations may still provide a means for monitoring changes in permeability of low‐porosity underground repositories of radioactive waste.
Meteorite ALHA81005: Petrology of a new lunar highland sample
Authors: Kurat Gero , Brandstätter Franz
Published: February 2008

Meteorite ALHA81005 is a shock‐compacted lunar highland regolith breccia. Besides glasses (fragments, spherules, matrix glass), chondrules (of ANT composition), and mineral fragments this new lunar sample contains principally three lithologies: 1) A pristine ferroan anorthosite suite consisting of anorthosites, norites, and one plagioclase peridotite. 2) A high‐Mg granulitic breccia suite representing variable mixtures of troctolitic and noritic precursor rocks. 3) A melt‐rock suite consisting of feld‐spathic basalts and metabasalts of a composition intermediate between (1) and (2). Most glass compositions and the chondrule compositions also project into this group. All lithologies and their derivatives are characteristically poor in alkalis. Neither a KREEP nor a mare basalt composition could be identified with certainty. ALHA81005 apparently comes from a highland area far from any mare basalt and KREEP source.
El Chichon eruption cloud: Latitudinal variation of the spectral optical thickness for October 1982
Authors: Spinhirne J. D.
Published: February 2008

Sun photometer measurements of the spectral optical thickness of the El Chichon eruption cloud were obtained during an airborne latitudinal survey. The measured optical thicknesses were greatly enhanced over background levels for the stratosphere. The observations covered 44°N to 36°S, and increased optical thickness was found at all latitudes where measurements were made. Significant variations in the magnitude and spectral dependence of the optical thickness were found within the latitude range covered by the observations. The maximum optical thickness was found at 20°N and the minimum was found at 30° S. The optical thickness values ranged between 0.13 and 0.017 at 870 nm and between 0.15 and 0.044 at 440 nm.
Plasma ion‐induced molecular ejection on the Galilean satellites: Energies of ejected molecules
Authors: Johnson R. E. , Boring J. W. , Reimann C. T. , Barton L. A. , Sieveka E. M. , Garrett J. W. , Farmer K. R. , Brown W. L. , Lanzerotti L. J.
Published: February 2008

First measurements of the energy of ejection of molecules from icy surfaces by fast incident ions are presented. Such results are needed in discussions of the Jovian and Saturnian plasma interactions with the icy satellites. In this letter parameters describing the ion‐induced ejection and redistribution of molecules on the Galilean satellites are recalculated in light of the new laboratory data.
A note on terrestrial heat flow in the Colorado Plateau
Authors: Reiter Marshall , Clarkson Gerry
Published: February 2008

The mean of deep heat‐flow measurements in the interior of the Colorado Plateau (temperature measurements to depths >750 m) is about 5 mWm−2 greater than the mean of shallow data. Although these data sets have remarkably similar means considering the experimental difficulties in measuring heat flow, the means never the less appear statistically different (59 mWm−2 vs 64 mWm−2). If various lithospheric heating models are used to explain the uplift of the Colorado Plateau, a 5 mWm−2 difference in surface heat flow will make the time of lithospheric heating very different. Deep heat‐flow data in the Colorado Plateau typically lack the large spatial variability that shallow data show. The deeper data should therefore relate better to regional geothermal trends caused by mantle thermal conditions and by crustal radioactivity. The deep heat‐flow data, where present, in the Colorado Plateau interior suggest a rather uniform heat flow and therefore rather constant mantle temperatures and crustal radioactivity. Continued concern with experimental data will be necessary to appreciate the uncertainties in the heat‐flow data and the resulting thermal models.
Spatial changes in the stratospheric aerosol associated with the north polar vortex
Authors: McCormick M. P. , Trepte C. R. , Kent G. S.
Published: February 2008

In late January and early February 1983, observations made by the Stratospheric Aerosol Measurement (SAM II) satellite system showed that aerosol extinction profiles measured within the northern polar vortex differed significantly above 18 km from those measured outside the vortex. Values of the calculated optical depths above 18 km for February 1, 1983, are lower by approximately one order of magnitude within the polar vortex than those outside. Similar differences were found in the aerosol backscattering profiles obtained using an airborne lidar system when crossing the polar vortex. Since potential vorticity at a constant altitude is not conserved across the polar vortex, horizontal adiabatic transport does not occur.
Nonlinear theory of Type I irregularities in the equatorial electrojet
Authors: Sudan R. N.
Published: February 2008

By taking into account the effect of wave electric fields on electron orbits, a nonlinear dispersion relation for Type I irregularities is obtained which predicts: (1) isotropy of the Doppler shift with elevation, (2) limiting phase velocity equal to ion acoustic speed, and (3) saturation amplitude which is maximum for horizontally propagating waves and decreases with elevation.
An examination of the Southern California field test for the systematic accumulation of the optical refraction error in geodetic leveling
Authors: Castle Robert O. , Brown Byron W. , Gilmore Thomas D. , Mark Robert K. , Wilson R. Clark
Published: February 2008

Appraisals of the two levelings that formed the southern California field test for the accumulation of the atmospheric refraction error indicate that random error and systematic error unrelated to refraction competed with the systematic refraction error and severely complicate any analysis of the test results. If the fewer than one‐third of the sections that met less than second‐order, class I standards are dropped, the divergence virtually disappears between the presumably more refraction contaminated long‐sight‐length survey and the less contaminated short‐sight‐length survey.
Anisotropies and flows of suprathermal particles in the distant magnetotail: ISEE 3 observations
Authors: Scholer M. , Gloeckler G. , Hovestadt D. , Ipavich F. M. , Klecker B. , Fan C. Y.
Published: February 2008

The ISEE‐3 spacecraft has been transferred in 1982 into an earth orbit which brings the satellite close to the tailward Lagrangian point L2 at ∼ 220 RE and thus allows exploration of the distant geomagnetic tail. We report in this letter initial analysis of energetic proton measurements > 30 keV from the Max‐Planck‐Institut/University of Maryland sensor system on ISEE‐3. We find that suprathermal protons are a persistent feature of the distant tail. Differential intensitites at 30 keV are essentially constant between the lunar distance and 220 RE and about one order of magnitude smaller than in the near earth (≲ 20 RE) plasma sheet. Assuming that these protons are convected with the local plasma flow we are able to derive plasma velocities. During time periods where a comparison is possible, these velocities compare favourably well with the velocities derived from the Los Alamos National Lab. plasma analyzer onboard the same spacecraft. The appearance of the plasma sheet as evidenced by the suprathermal particles is rather bursty, anisotropies are large and predominantly tailward.