bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheological properties of mudflows associated with the spring 1980 eruptions of Mount St. Helens Volcano, Washington
Authors: Fink Jonathan H. , Malin Michael C. , D'Alli Richard E. , Greeley Ronald
Published: February 2008

Rheological properties of three recent mudflows at Mount St. Helens were estimated using techniques developed for determining the properties of debris flows based on the geometry of their deposits. Calculated yield strengths of 1100, 1000, and 400 Pa, maximum flow velocities of 10 to 31 m/s, volumetric flow rates of 300 to 3400 m³/s, and plastic viscosities of 20 to 320 Pa‐s all compare favorably with measured and estimated values cited in the literature. A method for determining likely sites of future mudflow initiation based on these data is outlined.
Measurements of the height variation of sulfuric acid vapor concentrations in the stratosphere
Authors: Arnold F. , Fabian R. , Joos W.
Published: February 2008

Stratosperic sulfuric acid vapour concentrations have been measured in the altitude region from 23.5 to 33 km by the passive chemoionisation mass spectrometry method (PACIMS), in recent years sucessfully introduced by our group for stratospheric trace gas detection. The data agree with current model predictions at most heights. Implications of the present data for the stratosperic sulphur cycle, stratosperic aerosols, and stratosperic ions are discussed.
Attenuation of P and S waves in a magma chamber in Long Valley Caldera, California
Authors: Ryall Floriana , Ryall Alan
Published: February 2008

Shallow earthquakes around the southwest boundary of Long Valley caldera, west of the Hilton Creek fault, are characterized by lack of S‐waves at regional seismic network stations to the northwest, north and northeast, and P‐waves for these same station‐event combinations are deficient in frequencies higher than about 2‐3 Hz. Earthquakes east of the Hilton Creek fault and southeast of the caldera have normal P‐ and S‐wave signatures at the same stations. These effects are explained by propagation through a magma chamber in the south‐central part of Long Valley caldera, at depth greater than 7‐8 km.
Structure of the inner core inferred from observations of its spheroidal shear modes
Authors: Masters Guy , Gilbert Freeman
Published: February 2008

Spheroidal modes of elastic‐gravitational oscillation that have an energy partition dominated by shear energy in the inner core are called core modes. Recordings from the IDA gravimeter network of an earthquake in the Tonga region on June 22, 1977 have provided the first unambiguous observations of core modes. They conclusively show that, at low frequencies, the inner core has a very high Q (about 3500). They also tightly constrain the ratio of the inner core radius to the mean shear velocity to be 345s with an uncertainty of 0.5%.
Extended sulfuric acid vapor concentration measurements in the stratosphere
Authors: Viggiano A. A. , Arnold F.
Published: February 2008

The recent measurements of stratospheric H2SO4 vapor concentrations using passive chemoionisation mass spectrometry are continued. This work extends the altitude range of the measurements from 23.8 to 38.9 km. The results indicate a low concentration below approximately 30 km, followed by a sharp rise to a maximum value of 1 × 107 molecules cm−3 at 35 km. The concentration then decreases slowly with increasing height. The results are compared with previous measurements and theoretical models.
Acceleration of heavy ions on auroral field lines
Authors: Ashour‐Abdalla M. , Okuda H. , Cheng C. Z.
Published: February 2008

We present results of both a linear and a nonlinear study of oxygen cyclotron waves and the associated oxygen heating. Linear theory predicts that oxygen cyclotron waves will have smaller growth rates than hydrogen cyclotron waves. Results of a simulation study in which the free energy source is an initial drifting electron distribution indicate that oxygen cyclotron waves only grow to small amplitudes, while the hydrogen cyclotron waves achieve larger amplitudes. In an attempt to model more realistically the continuous ionospheric outflow, a simulation model is used, in which the electron velocity distribution is maintained by a constant flow of electrons. This latter model predicts that the oxygen waves grow to amplitudes much larger than the hydrogen waves resulting in the preferential heating of the heavier ions.
The distant bow shock and magnetotail of Venus: Magnetic field and plasma wave observations
Authors: Russell C. T. , Luhmann J. G. , Elphic R. C. , Scarf F. L.
Published: February 2008

An examination of the magnetic field and plasma wave data obtained by the Pioneer Venus orbiter in the wake region behind Venus discloses a well developed bow shock whose location is similar to that observed on previous missions in contrast to the dayside bow shock. Venus also has a well developed magnetotail in which the field strength is enhanced over magnetosheath values and in which the magnetic field is aligned approximately with the solar wind direction. The boundary between magnetosheath and magnetotail is also marked by a change in the plasma wave spectrum.
The Darfur Swell, Africa: Gravity constraints on its isostatic compensation
Authors: Crough S. Thomas
Published: February 2008

The free‐air gravity anomaly observed over the Darfur Swell is explainable by local isostatic balance with a root approximately 50 km deep on average. This root depth is similar to that inferred beneath other African domes and beneath oceanic midplate swells, suggesting that the Darfur Swell is a hotspot uplift created by lithospheric reheating.
Temperature dependent UV absorption cross sections for carbonyl sulfide
Authors: Molina L. T. , Lamb J. J. , Molina M. J.
Published: February 2008

The ultraviolet absorption cross sections of gaseous carbonyl sulfide, OCS, have been measured between 185 and 300 nm at 295K and 225K. The results agree well with previously reported values at wavelengths shorter than 270 nm. We found no evidence of longer wavelength absorption and hence we conclude that destruction of OCS by solar photolysis in the troposphere is negligible.
The Galapagos axial magnetic anomaly: Evidence for the Emperor Event within the Brunhes and for a two‐layer magnetic source
Authors: Wilson Douglas S. , Hey Richard N.
Published: February 2008

The axial (Brunhes) magnetic anomaly over the Galapagos spreading center shows consistent short‐wavelength anomalies that are not consistent with a uniformly magnetized layer. We interpret this anomaly to confirm the presence of the Emperor reversed event at 0.49 ± 0.05 mybp, with a duration about 0.01 m.y. Further, this anomaly is consistent with a two‐layer magnetic source, with the lower layer having very broad transition zones, offset away from the axis from those of the upper layer by about 10 km.
Stratospheric HF and HCl observations (15 June 1981)
Authors: Traub W. A. , Chance K. V.
Published: February 2008

We have measured seven far‐infrared rotational lines of HF and HCl from a balloon platform at 28.5 km. Other lines, including H2O and O3, were observed simultaneously. At an effective altitude of about 33 km, we find an abundance ratio HF/HCl= 0.18±0.02, and a water vapor mixing ratio of about 4 ppmv. Modelled values of HF/HCl for an atmosphere containing this much H2O are slightly higher, but in reasonable agreement.
Atmospheric trace gas measurements with a new clean air sampling system
Authors: Leifer R. , Sommers K. , Guggenheim S. F.
Published: February 2008

The development of a new clean air sampling system for the Department of Energy's WB‐57F aircraft has allowed the analysis of CCl3F (Fluorocarbon‐11), CCl2F2 (Fluorocarbon‐12), CHClF2 (Fluorocarbon‐22), C2Cl3F3 (Fluorocarbon‐113), CH4, CO, CO2, N2O, CH3Cl, CCl4, CH3CCl3, OCS and SF6 in tropospheric and stratospheric samples. Samples collected during the interception of the plume from the eruption of Mount St. Helens indicate that OCS was injected into the stratosphere during the eruption. A large CO2 gradient was found at 19.2 km on this flight.
Relationships between the solar wind electric field and the magnetospheric convection electric field
Authors: Lei Wu , Gendrin Roger , Higel Bernard , Berchem Jean
Published: February 2008

Past and recent studies of the empirical relations between the solar wind (SW) parameters and geomagnetic activity indices have provided a general understanding of the SW‐magnetosphere transfer processes. The present study deals with the relationship between the y‐component (GSM coordinate system) of the interplanetary electric field (IEF, Ey) and the low latitude magnetospheric convection electric field EM. This relationship provides an estimate of the field transfer efficiency between SW and magnetosphere. First the EM ‐field, which has been obtained from electron density profiles measured onboard the GEOS‐1 and ISEE‐1 spacecraft, is correlated directly with the corresponding Ey‐field, as calculated from published values of the interplanetary magnetic field and velocity [King, 1979] in a case‐by‐case study. Second, a statistical study is made between Ey and the geomagnetic index Km for low and moderate magnetic activity (Km ≤ 5+) from which one deduces a ’statistical’ relationship between Ey and EM. The transfer coefficients obtained by both methods are identical: ΔEM/ΔEy = 0.13. This result is discussed in the framework of present theories of SW‐magnetosphere transfer processes.
Turbulent accumulation of interplanetary magnetic fluxes at the Venus ionopause
Authors: Pérez‐de‐Tejada H.
Published: February 2008

The accumulation of interplanetary magnetic fluxes around the Venus ionopause is examined in the light of the PVO magnetometer and plasma wave measurements. It is argued that convective electric currents within the ionosphere are not sufficient to account for the observed geometry of the magnetic profiles. It is suggested that turbulent flow conditions forced in the ionosheath by the interaction process with the ionospheric plasma should produce an anomalous resistivity in the local flow and an effective lag in the transport of the interplanetary magnetic fluxes around the ionospheric obstacle. The enhanced magnetic fluxes seen above the ionopause should result from effective turbulent currents generated throughout the region of interaction.
Quantitative tests for plate tectonics on Venus
Authors: Kaula W. M. , Phillips R. J.
Published: February 2008

If plate tectonics exists on Venus, the rate of topographic dropoff from spreading centers should be about half that on Earth due to greater rock:fluid density contrast and lower temperature differential between the surface and interior. Using 1° × 1° mean elevations, 21,000 km of ridge were identified on Venus and 33,000 km on Earth. Heights h at distances up to ∼ 1000 km to either side of the ridges were analyzed to make least squares determinations of the parameters ho, Δh, and n in:

urn:x-wiley:00948276:media:grl1799:grl1799-math-0001
where s is off‐crest distance. The Venus ridges have a much less well‐defined mode in crest heights ho than the Earth ridges, and a somewhat smaller exponent n, on the average, indicating greater concavity. Fixing n to the theoretical value of 0.5, plate velocities were inferred from the Δh’s, using ∂h/∂(t½) from North Atlantic and North Pacific data. On Earth, these velocity solutions were compared to those from plate rotations, which indicate the ∂h/∂(t½) is probably about 40% too high for a global mean. The resulting plate creation rates on Venus (assuming comparable total heat generation and taking into account the density and temperature differences) are 0.7 km²/yr or less, and indicate that not more than 15% of Venus’s energy is delivered to the surface by plate tectonics, in contrast to 2.9 km²/yr and 70% energy delivery on Earth.
On long‐term thickening of the oceanic crust
Authors: McClain James S.
Published: February 2008

A number of studies of seismic refraction data have resulted in suggestions that the oceanic crust thickens with age, perhaps over a long time span. It is difficult to reconcile notions of crustal thickening with many of our ideas about crustal structure and formation. In this study we have re‐evaluated data compiled from a number of sources to obtain crustal thickness and age parameters for 105 different refraction profiles in the Pacific. An attempt was made to exclude data which might have poorly determined values of crustal thickness. The crust does appear to thicken with age to 30 or 40 m.y., but the effect is very subtle. Once probable biases are removed from the data, crustal thickening is not significant to a 95% confidence limit if ten m.y. samples are used. However, if one takes sample intervals of 0‐30 m.y. and 30‐100 m.y. there appears to be some difference in the average crustal thickness. Even in the latter case, the amount of thickening is far less than previous studies have suggested, only .45 km. Thus evidence for the long‐term addition of mass to the crust remains tenuous.
The role of charge exchange in the solar wind absorption by Venus
Authors: Gombosi T. I. , Horanyi M. , Cravens T. E. , Nagy A. F. , Russell C. T.
Published: February 2008

The amount of solar wind absorbed due to charge exchange processes in the dayside ionosheath of Venus is calculated. The calculations indicate the existence of a lower limiting ionopause altitude, below which all solar wind particles are removed from the flow by charge exchange. It is suggested that the cold and slow new ions, resulting from this interaction, play an important role in building the magnetic barrier observed just outside the ionopause, and also in creating the dayside “mantle” and downstream “penumbra” regions. The total absorption caused by charge exchange is typically 2‐5%, but it can reach values as high as 16%, when the solar wind dynamic pressure is very high.
Venus nightside ionospheric holes: The signatures of parallel electric field acceleration regions?
Authors: Grebowsky J. M. , Curtis S. A.
Published: February 2008

Recent observations by the instruments onboard the Pioneer Venus spacecraft have revealed the existence of "holes" or regions of density depletion in the nightside Venus ionosphere associated with regions of radial magnetic fields. The properties of the electrons within the core of these holes are suggestive of an acceleration process along the magnetic field lines as are the Venera 9 and 10 observations of energetic ions in the Venus tail. Given the observational information, we attribute these Venusian plasma depletions to the presence of parallel electric fields similar to those observed in the terrestrial auroral ionosphere. The resulting electric field accelerates electrons down the field lines producing heating of the depleted thermal electron population within the hole and production of ionization below the hole. Simultaneously ionospheric ions are accelerated outward toward the plasmasheet.
Ambient sulfate concentrations and windflow patterns at Whiteface Mountain, New York
Authors: Parekh Pravin P. , Husain Liaquat
Published: February 2008

Particulate sulfate in air was monitored daily from 15 June 1978 to 31 December 1979 at Whiteface Mountain, New York. The daily SO42− concentrations were related to surface‐air trajectory ensembles to assess the relative contribution from the U.S. and from Canada. During the study period the site was influenced approximately equally by continental polar and maritime tropical air masses. However the maritime air masses from the U.S. were the principal conveyors of high SO42− concentrations at this site and transported about 4 to 5 times more SO42− than did the continental polar air masses from Canada.
Twenty three year cycle in surface temperatures during the Maunder Minimum
Authors: Hameed S. , Wyant P.
Published: February 2008

We have compared power spectra of Manley's record of central England temperatures for the Maunder minimum with later periods. We find that the power in the ∼23 year cycle is statistically significant in the Maunder minimum portion of this temperature time series. This gives indirect support to the recent suggestion that the solar cycle persisted in the Maunder minimum even though normal sunspot activity was not observed. Our results also indicate that the ∼23 year cycle was stronger during the Maunder minimum than later times in this record.
Latitudinal variation of HNO3, HCl and HF vertical column density above 11.5 km
Authors: Girard André , Gramont Louis , Louisnard Nicole , Le Boiteux Sylvie , Fergant Gilbert
Published: February 2008

Simultaneous spectral observations in the atmosphere have been obtained for HNO3, HCl and HF in April‐May 1980, by the solar occultation technique, from an aircraft, between 64° North and 62° South. For these three species, the vertical column density above 11.5 km increases from low latitude in both hemispheres.
Plasmaspheric helium ion distribution from satellite observations of He II 304‐Å
Authors: Chakrabarti Supriya , Paresce Francesco , Bowyer Stuart , Chiu Yam T. , Aikin Arthur
Published: February 2008

High sensitivity and spatial resolution observations of the He II 304‐Å emission line intensity in the earth’s nightglow have been carried out by the Extreme Ultraviolet telescope on the Apollo‐Soyuz mission in July, 1975. The data, obtained over a wide range of plasmasphere parameters, are compared to the predictions of a kinetic equilibrium model of plasmaspheric ion density. Excellent agreement between observation and theory is found using as inputs a temperature model, solar flux and H+ and O+ number densities determined by extrapolating nearly simultaneous Atmospheric Explorer C measurements at 300 km. The observations in the northern hemisphere are well fit by a model having 285 He+ ions cm−3 at 500 km independent of latitude or longitude, while those in the south require 430 He+ ions cm−3 at the same altitude. This result is consistent with available information on the interhemispheric asymmetry of He+ observed by a mass spectrometer on Explorer 32 and on the winter neutral helium bulge.
The effect of compressive stress on the fracture energy of Sioux quartzite
Authors: Peck Lindamae , Gordon Robert B.
Published: February 2008

The fracture energy of Sioux quartzite in air and water measured with the wedge‐loaded double cantilever beam fracture specimen is found to depend on the angle of the wedge used. The measured fracture energy is greater when the wedge is sharper. This is ascribed to the decrease in the compressive stress acting on the specimen. It is proposed that the compressive stress aids in the formation of the microcracks necessary for crack extension. Measurements of the width of the microcrack zone (visible with the scanning electron microscope) adjacent to the primary crack support this interpretation.
Narrow bursts of intense electron precipitation fluxes within inverted‐V events
Authors: Lin C. S. , Hoffman R. A.
Published: February 2008

Inverted‐V events have been examined in detail to identify small scale structures within them which might be related to auroral arcs. The rate of energy deposition into the atmosphere by the precipitating electrons of inverted‐Vs was computed from the energy spectra measured by the AE‐D satellite for 30 passes. Bursts of high deposition rate with a short duration (<5 seconds) were found inside inverted‐V events. From an examination of 45 bursts, most bursts were found to have a latitudinal width less than 0.2°, and occurred from 65° to 75° invariant latitude during the evening hours (19‐01 MLT). Optical emission intensities of 5577 Å and 6300 Å were inferred from the measured electron fluxes to show these bursts capable of producing bright emissions. These results suggest that the electron fluxes of these narrow bursts have the proper characteristics to cause discrete auroral arcs in the atmosphere.
A geomagnetic field spectrum
Authors: Langel R. A. , Estes R. H.
Published: February 2008

Selected MAGSAT data are used to derive a spherical harmonic model of the earth’s internal magnetic field of degree and order 23. The power spectrum, with terms of the form (Mauersberger, 1956; Lowes, 1974):

urn:x-wiley:00948276:media:grl1890:grl1890-math-0001
is computed. It exhibits a distinct change of slope at about n = 14 which is interpreted to mean that the field from the core dominates for n ⩽ 13 and the field from the crust for n ⩾ 15. The two portions of the spectrum are well represented by: Rn = 1.349 × 109 (0.270)n (nT)² for the core and Rn = 37.1 (0.974)n (nT)² for the crust. These representations can be used to establish order of magnitude inaccuracies in core field models due to crustal fields and due to inability to “observe” the core field wavelengths beyond n = 13 which are totally obscured by the crustal field.
Initial scalar magnetic anomaly map from MAGSAT
Authors: Langel R. A. , Phillips J. D. , Horner R. J.
Published: February 2008

A scalar magnetic anomaly map between ±50° geographic latitude was derived from MAGSAT data acquired during the November 1979 to June 1980 mission lifetime. Separation of anomaly fields from core and external fields was accomplished utilizing techniques developed for POGO data (Mayhew, 1979; Langel et al., 1980). Comparison with a similar map from POGO data shows that the basic anomaly patterns are essentially reproducible except in a few regions such as the Atlantic and Pacific at latitudes south of −15°. Increased resolution due to a lower measurement altitude is evident in the MAGSAT map.
Detection of an ionospheric current for the preliminary impulse of the geomagnetic sudden commencement
Authors: Araki T. , Iyemori T. , Tsunomura S. , Kamei T. , Maeda H.
Published: February 2008

MAGSAT observed a geomagnetic sudden commencement at an altitude of 550 km on its dawnside orbit above the South Atlantic Ocean. The H‐component of the magnetic field increased monotonically by 46 nT in about 4 minutes, while the D‐component decreased westward by 10 nT in the first 1‐2 minutes and then increased gradually. There was no significant deviation in the Z‐component. The comparison with ground‐based magnetograms showed that the negative impulse of the D‐component provided the first experimental evidence of the global ionospheric current system for the preliminary impulse of the geomagnetic sudden commencement.
Voyager observations of solar wind proton temperature: 1‐10AU
Authors: Gazis Paul R. , Lazarus Alan J.
Published: February 2008

Solar wind proton temperatures are measured simultaneously by the Voyager 1 and 2 spacecraft, far from Earth, and the IMP 8 spacecraft in Earth orbit. This technique allows the separation of radial and temporal variations of solar wind parameters. The average value of the proton temperature from 1 to 9 AU is observed to decrease as r−0.7 ± 0.2 which is slower than would be expected for adiabatic expansion. A detailed look at the solar wind stream structure shows that considerable heating occurs at the interface between high and low speed streams.
Measurements of nitric oxide during a stratospheric warming
Authors: Knight W. , Hastie D. R. , Ridley B. A.
Published: February 2008

The altitude distribution of NO was measured between 12 and 33 km near 54°N during the stratospheric warming of February, 1979. The NO mixing ratios were considerably smaller compared to summer conditions, especially below 23 km. The measurements are used to estimate the distribution of NO2 for comparison with ground‐based column measurements and to show that during the warming NOx is at least a factor of two lower than is observed in summer at this latitude. This reduction in NOx is shown to be consistent with a larger fraction of odd‐nitrogen existing as N2O5.
Venus: Limited extension and volcanism along zones of lithospheric weakness
Authors: Schaber Gerald G.
Published: February 2008

Three global‐scale zones of possible tectonic origin are described as occurring along broad, low rises within the Equatorial Highlands on Venus (lat 50° N. to 50° S., long 60° to 310°). The two longest of these tectonic zones, the Aphrodite‐Beta and Themis‐Atla zones, extend for 21,000 and 14,000 km, respectively. Several lines of evidence indicate that Beta and Atla Regiones, located at the only two intersections of the three major tectonic zones, are dynamically supported volcanic terranes associated with currently active volcanism. Rift valleys south of Aphrodite Terra and between Beta and Phoebe Regiones are characterized by 75‐ to 100‐km widths, raised rims, and extensions of only a few tens of kilometers, about the same magnitudes as in continental rifts on the Earth. Horizontal extension on Venus was probably restricted by an early choking‐off of plate motion by high crustal and upper‐mantle temperatures, and the subsequent loss of water and an asthenosphere.
Multiple solutions for convection in a two component fluid
Authors: Busse Friedrich H.
Published: February 2008

Convection in a fluid layer heated from below with two immiscible components A and B of the same average density exhibits different states of motion. Besides a solution describing convection in sublayers other solutions in which fluid B is surrounded by streamlines of fluid A or vice versa are possible. Potential applications to the problem of mantle convection are discussed.
Hypocenter for the 1979 Imperial Valley Earthquake
Authors: Archuleta Ralph J.
Published: February 2008

Using P‐and S‐wave arrival times with the laterally varying P‐wave velocity structure derived from analysis of a refraction survey of the Imperial Valley, a hypocenter is ascertained for the October 15, 1979, Imperial Valley earthquake:

Latitude 32° 39.50′N,Longitude 115° 19.80′W,Depth 8.0 km,Time 23:16:54.40 GMT.
Mantle phase transitions and the free air gravity anomalies over Fennoscandia and Laurentia
Authors: Peltier W. R. , Wu Patrick
Published: February 2008

The interpretation of free air gravity anomalies over present day centers of postglacial rebound has always been controversial. We show that the observed gravity anomalies over both Fennoscandia and Laurentia and the associated relative sea level variations since deglaciation are explicable with a simple Newtonian viscoelastic model of the earth if the earth model includes the density jumps in the mantle associated with the phase transitions at 420 and 670 km depth. The result has important implications for mantle convection since the observed free air anomalies are very sensitive to the viscosity of the mantle beneath the deepest phase transition.
Large‐amplitude magnetic variations in quasi‐parallel shocks: Correlation lengths measured by ISEE 1 and 2
Authors: Greenstadt E. W. , Hoppe M. M. , Russell C. T.
Published: February 2008

Wide separations up to more than 1 RE between ISEE 1 and 2 during the second half of 1978 have been used to measure the correlation length of magnetic pulsations in quasi‐parallel shocks. When the two spacecraft were less than a few hundred km apart, magnetic oscillations measured by magnetometers on both spacecraft exhibited virtually identical waveforms, but at distances of several thousand km, the two time series of field variation showed no detailed similarity at all. The correlation coefficients of the pulsations dropped from close to 1.0 for spacecraft separations of less than 100 km to 0.2 for separations of greater than 800 km. A correlation length of several hundred km may be related to the gyroradius of return protons with energy typical of the peaks of diffuse and beam ion distributions.
Length of day and obliquity of the ecliptic 850 MA ago: Preliminary results of a stromatolite growth model
Authors: Vanyo J. P. , Awramik S. M.
Published: February 2008

A sinusoidal growth pattern in a columnar stromatolite from the approximately 850 million year‐old Bitter Springs Formation suggests a method for deducing length of day and other geophysical parameters. Phototropic microorganisms following the seasonal inclination of the Sun are proposed as responsible for the estimated 410 or more laminae (daily) per sine wave (annual). A preliminary paleomagnetic analysis yields results consistent with the proposed model.
The faint young Sun‐climate paradox: Volcanic influences
Authors: Schatten Kenneth H. , Endal Andrew S.
Published: February 2008

It has been suggested that the early earth may have frozen over as a result of a fainter early sun (see Ulrich, 1975). If this had happened, climate models suggest the earth would have remained frozen through the present epoch and into the distant future. We suggest that volcanic influences could allow a passage from the frozen branch into the unfrozen branch of climate models should conditions on earth be suitable for the latter climate change. A broad equatorial belt of volcanic ash is one scenario which would allow a transfer from the frozen earth state into the unfrozen one.
The relation between air mass trajectories and the water isotope composition of rain in the Mediterranean Sea area
Authors: Rindsberger M. , Magaritz M. , Carmi I. , Gilad D.
Published: February 2008

The isotopic composition of rainwater near Nahariya, Israel, was measured in 12 individual storms during the winter months of 1980/1981. Rains most depleted in the heavy stable isotopes and enriched in tritium are associated with air masses which come from North East Europe and have a short, intense interaction with the East Mediterranean Sea. Storms most enriched in 18O and D and depleted in tritium are associated with air masses which come from the Atlantic Ocean and enter the Mediterranean Sea on its western part, travelling along the North African Coast, sometimes with a southerly shift. A relatively high correlation coefficient was found between the stable isotopic content of precipitation and the 800 mb temperature.
Strain‐rate profile across the Elsinore, San Jacinto, and San Andreas Faults near Palm Springs, California, 1973‐81
Authors: King N. E. , Savage J. C.
Published: February 2008

A profile of the strain accumulation rate along a line trending N50°E across the subparallel Elsinore, San Jacinto, and San Andreas faults near Palm Springs, California, has been constructed from trilateration surveys in the 1973‐81 interval. The strain accumulation is principally right‐lateral shear across a vertical plane parallel to fault strike (N40°W). The strain rate profile for that component exhibits two clearly resolved maxima, one centered on the San Jacinto fault (γmax = 0.35 ± 0.02 µrad/a) and the other on the San Andreas fault (γmax = 0.40 ± 0.02 µrad/a); no maximum is associated with the Elsinore fault. This result clearly implies that slip at depth on both the San Andreas and San Jacinto faults is loading the shallower sections of these faults, and that eventually rupture can be expected on both.
Magnetic anisotropy and porosity of chondrites
Authors: Sugiura N. , Strangway D. W.
Published: February 2008

The measured magnetic anisotropy and porosity of various chondrites are found to be inversely correlated when they are considered by class of chondrites (E, H and L + LL). For chondrites with similar porosities, the anisotropies for H and E chondrites are smaller than for L and LL chondrites, which have lower metal contents. The anisotropy and porosity are not dependent on the metamorphic grade of chondrites. K‐Ar ages of strongly anisotropic and/or less porous chondrites are younger than those of less anisotropic and/or more porous chondrites. These observations suggest that impacts which reset the K‐Ar ages produced the anisotropy and reduced the porosity of chondrites.
Effects of solution mass transport on the ECC ozonesonde background current
Authors: Thornton Donald C. , Niazy Nagla
Published: February 2008

When the electrochemical concentration cell (ECC) ozonesonde exhibits a background current at the time of balloon launch, the measured cell current must be corrected to obtain the actual ozone response. We have found a pressure dependent factor in the background current that originates in a convective mass transport parameter. For atmospheric pressures greater than 100 mb, the mass transport parameter is constant, but at pressures less than 100 mb it declines logarithmically with pressure. We suggest that the background current correction is directly correlated to the mass transport parameter pressure dependence. Compared to a constant background current, the presently used background current correction based on the oxygen partial pressure leads to an overestimate of the integrated ozone value in the troposphere for the ECC ozonesonde data.
Solar Mesosphere Explorer: Scientific objectives and results
Authors: Barth C. A. , Rusch D. W. , Thomas R. J. , Mount G. H. , Rottman G. J. , Thomas G. E. , Sanders R. W. , Lawrence G. M.
Published: February 2008

Instruments on the Solar Mesosphere Explorer simultaneously measure ozone density, temperature, and solar ultraviolet flux. Results from six months of observations show that ozone density in the mesosphere changes from day‐to‐day and with the seasons and that the principal cause of these changes is the variation in atmospheric temperature. The dependence between ozone density and temperature is inverse, with a decrease in temperature producing an increase in ozone density. This dependence is observable in the seasonal patterns and also in orbit‐to‐orbit observations during dramatic atmosphere changes such as stratospheric warmings.
Variation with age of the deep structure of the Pacific Ocean inferred from very long‐period Rayleigh wave dispersion
Authors: Montagner J. P. , Jobert N.
Published: February 2008

The propagation of Rayleigh waves along 44 direct paths across the Pacific Ocean is studied and a regionalization of the dispersion according to the age of the sea floor is performed. The group velocity dispersion curves characteristic of each one of four age regions considered are obtained for periods up to 300 s. These curves show an increase of group velocities with age over the whole period range considered. The shear wave velocity models inferred yield a lithosphere thickening with age and show the presence below the lithosphere of two zones where negative velocity anomalies decrease with increasing age : the low velocity zone and a zone at a depth of 350 km.
Multiple SCS travel times and attenuation beneath Mexico and Central America
Authors: Lay Thorne , Wallace Terry C.
Published: February 2008

Multiple ScS phases recorded for the June 19, 1982 El Salvador earthquake (Ms = 7.0) are analyzed to determine whole mantle attenuation and upper mantle travel time anomalies beneath Mexico, Central America and northern South America. Recordings from the ultra long‐period seismographs at Pasadena and Berkeley and the SRO station ANMO provide eight ScSn arrivals with 15 bouncepoints concentrated within Mexico. The whole mantle QScS for these paths is estimated as 145 ± 27 in the frequency range 8 to 40 mHz, and the average ScSn+1−ScSn JB residual (ΔTScS) at a period of 50 sec is +1.5 sec. Eight ScSn phases of similar periods recorded at GDSN stations in South America yield a QScS estimate of 232 ± 89 and ΔTScS = −3.9 sec for paths beneath Central America, and QScS = 93 ± 17 and ΔTScS = +0.3 sec for paths beneath northern South America. These results indicate that the variations in travel times and attenuation beneath continental regions are as pronounced as differences reported between old oceanic and stable shield regimes.
Effect of recent rate data revisions on stratospheric modeling
Authors: Ko Malcolm K. W. , Sze Nien Dak
Published: February 2008

Incorporation of recent revisions in rate data for several key reactions (NASA‐JPL, 1982) into our 1‐D model leads to higher OH concentration in the upper stratosphere. Accordingly, the calculated upper stratospheric ClO concentration is higher and appears to be in better agreement with observations. However, the calculated present day upper stratospheric ozone concentration is significantly reduced as a result of higher OH and ClO and the faster rate for O + HO2. It is shown that the use of smaller O2 cross‐section in the Herzberg continuum implies even lower ozone concentration in the upper stratosphere, causing further deterioration of the agreement between model and observations. The effects of the new rate data on the calculated steady state ozone depletion due to release of CFCs are discussed.
Effects of the El Chichon volcanic dust cloud on insolation measurements at Corvallis, Oregon (U.S.A.)
Authors: Rao C. R. Nagaraja , Bradley William A.
Published: February 2008

Insolation measurements made on clear days at Corvallis, Oregon, since the last week of November, 1982, have indicated a decrease of about 14% in the atmospheric clearness index, an increase by a factor of about 2.3 in the ratio of the diffuse sky irradiation to the global irradiation and a decrease of about 28% in the transmittance of the atmosphere for the direct normal solar irradiation compared to the normal, clear‐day values. It is felt these anomalies are caused by the increased atmospheric turbidity due to the El Chichon volcanic dust cloud.
First VHF auroral radar interferometer observations
Authors: Providakes J. P. , Swartz W. E. , Farley D. T. , Fejer B. G.
Published: February 2008

The radar interferometer technique first used at the magnetic equator in Peru is also a very powerful means for studying auroral plasma instabilities. We present here the first results, obtained with a 49.92 MHz, 20‐25 KW peak power pulsed radar located in Ithaca, NY (42.5° N, 76.4° W). Strong auroral echoes were obtained during several highly active periods. Phase differences between the signals received on the two antennas accurately determine the E‐W position, within the scattering volume, of localized scattering centers, and changes in this phase determine the corresponding velocity. The signal Doppler shift describes radial (essentially N‐S) motion. The data provide detailed information on the turbulent structure of the echoing region and show clearly that different features in the Doppler power spectrum often represent signals coming from different locations. If we assume that the radial and transverse phase velocities represent real drift velocities, we can determine full horizontal velocity vectors from the data and hence the horizontal electric field, usually with a time resolution of the order of 15‐30s.
Dynamical evolution of interplanetary magnetic fields and flows between 0.3 AU and 8.5 AU: Entrainment
Authors: Burlaga L. F. , Schwenn R. , Rosenbauer H.
Published: February 2008

The radial evolution of interplanetary flows and associated magnetic fields between 0.3 AU and 8.5 AU was analyzed using data from Helios 1 and Voyager 1, respectively. During a 70‐day interval in 1980 Voyager 1 observed two streams which appeared to be recurrent and which had little fine structure. The corresponding flows observed by Helios 1 were much more complex, showing numerous small streams, transient flows and shocks as well as a few large corotating streams. It is suggested that in moving to 8 AU the largest corotating streams swept up the slower flows (transient and/or corotating streams) and shocks into a relatively thin region in which they coalesced to form a single large‐amplitude compression wave. We refer to this combined process of sweeping and coalescence as "entrainment". The resulting large‐amplitude compression wave is different from that formed by the steepening of a corotating stream from a coronal hole, because different flows from distinct sources, with possibly different composition and magnetic polarity, are brought together to form a single new structure. As a result of entrainment, memory of the sources and flow configurations near the sun is lost. Small‐scale features are erased as the flows move outward and energy is transferred from small scales to large scales by entrainment. Thus in the outer solar system the structure of the solar wind may be dominated by large scale pressure waves (compressions followed by rarefactions) separated by several AU. Beyond several AU most of the compression waves are no longer driven by streams, and the compression waves expand freely. At large distances (≳ 25 AU) they will have interacted extensively with one another producing yet another state of the solar wind, with fewer large‐scale non‐uniformities and more small‐scale non‐uniformities.
An analysis of a possible episodic plume trace in West Africa
Authors: Ajakaiye D. Enilo , Verheijen Peter J. T.
Published: February 2008

The evolution of a plume trace which constitutes the granitic intrusives in the Hoggar, Air, Zinder and the Jos plateau regions has been analyzed using geochronological and topographic data. The trace location is consistent with the idea of the African plate rotating around a pole in West Africa located at about 1.0°W and 13.9°N with an angular velocity of about 0.216 degrees/my during the Cambrian to the Jurassic period, possibly with a small deceleration. The major activity seems to occur at intervals of 125 ± 6 my.
Large amplitude middle atmospheric electric fields: Fact or fiction?
Authors: Kelley M. C. , Siefring C. L. , Pfaff R. F.
Published: February 2008

Measurements of large apparent D.C. electric fields (∼V/m) in the middle atmosphere made by two sounding rockets are carefully analyzed and shown to be spurious. This may shed some doubt on recent measurements of large D. C. electric fields by other experimenters. Evidence is presented, for one rocket, indicating that the measured electric fields are aligned with the velocity vector of the rocket. This suggests the possibility that the measured electric fields are due to a negatively charged wake. A comparison of measurements made by different electric field booms is also presented. We see that in one experiment insulating coatings on the booms may have affected our results. It is the authors' opinion that insulating coatings should not be used at mesospheric altitudes because of possible detrimental effects such as frictional charging.
A statistical study of the dynamics of the equatorward boundary of the diffuse aurora in the pre‐midnight sector
Authors: Sauvaud J. A. , Crasnier J. , Galperin Yu. I. , Feldstein Y. I.
Published: February 2008

We present a statistical study of the dynamics of the equatorward boundary of the diffuse aurora. This Soft Electron Boundary appears to be best fitted by using the AE index values averaged over the 5 hours preceding the measurements. This inertia of the boundary is interpreted as indicative (1) of the action of a polarization electric field braking the inward motion of the corresponding equatorial plasma during increasing magnetic activity so that several successive perturbations are needed to obtain a consequent inward displacement and (2) of a weak wave‐particle interaction during periods of decreasing magnetic activity.
A theory of long period magnetic pulsations, 3. Local field line oscillations
Authors: Hasegawa Akira , Tsui King H. , Assis Altair S.
Published: February 2008

The local magnetic field is shown to oscillate at its Alfvén resonance frequency(ies) in response to a wide band source whose frequency range covers the resonance frequency(ies). The proposed mechanism explains certain observations of magnetic pulsations where the frequency is found to vary continuously as a function of latitude for a given event.
The discovery and initial characterization of Allan Hills 81005: The first lunar meteorite
Authors: Marvin Ursula B.
Published: February 2008

Antarctic meteorite ALHA81005, discovered in the Allan Hills region of Victoria Land, is a polymict anorthositic breccia which differs from other meteorites in mineralogical and chemical composition but is strikingly similar to lunar highlands soil breccias. The petrologic character and several independent lines of evidence identify ALHA81005 as a meteorite from the Moon. Two small clasts of probable mare basalt occur among the highlands lithologies in Thin Section 81005,22. This lunar specimen, which shows relatively minor shock effects, has generated new ideas on the types of planetary samples we may find on the Earth, and has added fresh excitement to the Antarctic meteorite program.
Oxygen and silicon isotopes in ALHA 81005
Authors: Mayeda Toshiko K. , Clayton Robert N. , Molini‐Velsko Carol A.
Published: February 2008

The Antarctic meteorite ALHA 81005 has oxygen and silicon isotopic compositions identical with lunar highland rocks. The oxygen is distinctly unlike that in calcium‐rich achondrites. The isotopic data are entirely consistent with a lunar origin for the meteorite.
Recent cosmic ray exposure history of ALHA 81005
Authors: Tuniz C. , Pal D. K. , Moniot R. K. , Savin W. , Kruse T. H. , Herzog G. F. , Evans J. C.
Published: February 2008

Measurements of the 10Be and 26Al contents of ALHA 81005 constrain the length and conditions of its exposure to cosmic rays. Calculations based on one‐step irradiation models imply that the time spent by this object in space is shorter than that spent by most ‘asteroidal’ meteorites. On the other hand the results are readily consistent with a lunar origin for ALHA 81005.
Antarctic Meteorite ALHA 81005, A piece from the ancient lunar crust
Authors: Palme H. , Spettel B. , Weckwerth G. , Wänke H.
Published: February 2008

A 128 mg sample of the Antarctic meteorite ALHA 81005 was analysed for major, and trace elements by instrumental neutron activation techniques. The meteorite, or at least its major components, may be older than 4 billion years and represent a piece of the ancient lunar crust, before the formation of the large basins on the front‐side of the Moon. The evidence is derived from the low absolute content of incompatible elements and their slightly different fractionation pattern from KREEP, the dominant source for these elements on the front‐side. The basically chondritic pattern of siderophile elements (Ni, Co, Ir, Au) is clearly distinguished from younger, basin related, meteoritic components.
Compositional implications regarding the lunar origin of the ALHA81005 Meteorite
Authors: Kallemeyn Gregory W. , Warren Paul H.
Published: February 2008

Geochemically, ALHA81005 has all the attributes expected of a regolith sample from the lunar highlands. Most important is its Fe/Mn ratio (77), within uncertainty the same as the mean lunar ratio. There are significant differences, however, in comparison to previously sampled lunar regoliths. The closest precedents are the Apollo‐16 and Luna‐20 regoliths, particularly the latter, but ALHA81005 has lower contents of Na, Ti, and incompatible elements. Feldspathic granulitic breccias such as 72559, which texturally resemble the most abundant type of clast in ALHA81005, are also similar compositionally. From its low KREEP and Na contents we infer ALHA81005 originated well away from the K, Th, and U‐rich region near the center of the nearside, at least as far away as the eastern limb.
A unified theory of cosmic ray diurnal variations
Authors: Bieber J. W. , Pomerantz M. A.
Published: February 2008

The various observed harmonics of the cosmic ray diurnal variation may be understood on a unified basis if the free space cosmic ray anisotropy is non‐sinusoidal in form. The major objective of this report is to emphasize that such a non‐sinusoidal anisotropy is a natural result of the normal interplanetary transport processes of pitch angle scattering and adiabatic focusing in a spatially varying mean field. Interplanetary scattering parameters λ ∼ 0.5 AU and q ∼ 1.1 at 10 GV rigidity — values that are quite consistent with current knowledge of interplanetary transport processes — lead to predicted semidiurnal and tridiurnal variations that agree with observation. Thus, there is no need to invoke exotic processes to explain the higher order harmonics of the cosmic ray diurnal variation.