bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxides of nitrogen and the clouds of Venus
Authors: Watson A. J. , Donahue T. M. , Stedman D. H. , Knollenberg R. G. , Ragent B. , Blamont J.
Published: February 2008

Nitric Oxide may be produced in the atmosphere of Venus by lightning storms in the clouds. Here we suggest that the odd nitrogen thus formed may play an important part in the chemistry of the clouds. Specificallywe estimate production rates for NO2 in the limiting case of high NO concentrations. If the NO density is high we suggest that NO2 may catalyse the production of sulfuric acid aerosol from sulfur dioxide and water vaporand may also form nitrogen‐sulfur compounds such as nitrosyl sulfuric acidNOHSO4. The "large particles" seen by the Pioneer Venus sounder probe may contain considerable quantities of NOHSO4. If this is the case odd nitrogen must be present in the atmosphere in at least a parts‐per‐million mixing ratio.
Shearing of saturated clays in rock joints at high confining pressures
Authors: Wang Chi‐yuen , Mao Nai‐hsien
Published: February 2008

Saturated clays are sheared between rock joints at various pore water pressures and at confining pressures up to 3 kb (300 Mpa). Sliding on these joints is stable. For a given claythe shear stress required to initiate sliding increases linearly with the effective normal stress across the sliding surfacewith a slope of 0.08 ± 0.01 for joints filled with saturated montmorillonite0.12 ± 0.01 with saturated chlorite0.15 ± 0.01 with saturated kaoliniteand 0.22 ± 0.02 with saturated silty illite. Thus at high confining pressures the shear stress required to initiate sliding on joints filled with saturated clays are very much smaller than that required to initiate sliding on clean rock joints or on joints filled with dry gouge materials. In the crustsaturation of gouge materials along active faults would greatly lower the frictional resistance to faulting and would stabilize fault movement. Different fault behaviors such as stable creep along some faults and intermittent but sudden slip along others may reflect in part different degrees of saturation of fault zones at depth.
High resolution absorption coefficients for freon‐12
Authors: Hoell J. M. , Bair C. H. , Harward C. , Williams B.
Published: February 2008

Ultra high resolution absoprtion coefficients of the Q‐branch of Freon‐12 (CCℓ2F2) have been obtained using tunable diode laser spectroscopy. Continuous spectra are presented from 1155 cm−1 to 1163 cm−1 with a spectral resolution ∼ .001 cm−1. Absolute wavelength calibration was obtained using SO2 spectra as a standard and a 5 cm Ge etalon for relative calibration between SO2 lines. The relative accuracy of the Freon‐12 line positions was ∼ .0005 cm−1. The Freon‐12 dataobtained at a pressure of .05 Torrexhibited a rich and highly structured spectra. Howeverwith the exception of three isolated features at 1158.21159and 1161 cm−1 collisional broadening reduces the spectra to a structureless continuum for nitrogen pressures greater than 20 Torr. The spectra at 1161 cm−1 continue to exhibit structure at atmospheric pressure.
High latitude plasma convection: Predictions for Eiscat and Sondre Stromfjord
Authors: Sojka J. J. , Raitt W. J. , Schunk R. W.
Published: February 2008

We have used a plasma convection model to predict diurnal patterns of horizontal drift velocities in the vicinity of the EISCAT incoherent scatter facility at TromsoNorway and for Sondre StromfjordGreenlanda proposed new incoherent scatter facility site. The convection model includes the offset of 11.4° between the geographic and geomagnetic poles (northern hemisphere)the tendency of plasma to corotate about the geographic poleand a magnetospheric electric field mapped to a circle about a center offset by 5° in the antisunward direction from the magnetic pole. Four different magnetospheric electric field configurations were consideredincluding a constant cross‐ tail electric fieldasymmetric electric fields with enhancements on the dawn and dusk sides of the polar capand an electric field pattern that is not aligned parallel to the noon‐midnight magnetic meridian. The different electric field configurations produce different signatures in the plasma convection pattern which are clearly identified. Both of these high‐latitude sites are better suited to study magnetospheric convection effects than either ChatanikaAlaska or Millstone HillMassachusetts. Alsoeach site appears to have unique capabilities with regard to studying certain aspects of the magnetospheric electric field.
Laboratory studies of the charge neutralization of a rocket payload during electron beam emission
Authors: Bernstein W. , Whalen B. A. , Harris F. R. , McNamara A. G. , Konradi A.
Published: February 2008

The charge neutralization of an electrically‐isolated rocket payload emitting an energetic electron beam has been studied in experiments in the large vacuum chamber at Johnson Space Center. The introduction of an RF‐discharge‐produced ambient plasma density (104 ‐ 5 × 104 cm−3) reduces the payload potential to < 200 V for low current (1 and 10 ma) beams. The ignition of the beam‐plasma discharge provides an efficient neutralization process for higher current beams.
Atomic nitrogen in the upper atmosphere of Venus
Authors: Kasprzak W. T. , Hedin A. E. , Niemann H. B. , Spencer N. W.
Published: February 2008

Atomic nitrogen has been detected in the upper atmosphere of Venus by the Pioneer‐Venus Orbiter Neutral Mass Spectrometer (ONMS). Surface recombination of atomic nitrogen with atomic oxygen to form nitric oxide in the ion source allows it to be detected at mass 30. The scale height temperature of the mass 30 peak agrees with the scale height temperatures of the other species if it is assumed to be derived from atomic nitrogen. The diurnal variation of atomic nitrogen is approximately proportional to that of atomic oxygen with an estimated N/O ratio of 1.5% at 150 km.
NO3 in the troposphere
Authors: Noxon J. F. , Norton R. B. , Marovich E.
Published: February 2008

NO3 has been measured in slightly polluted Colorado mountain air up to a few hundred ppt. There is clear evidence that it is removed by scavenging reactions in less than one hour. The identity of the scavenger is not yet established in mountain air, nor is it yet known whether the reaction removes odd nitrogen from the troposphere. In urban air the scavenging occurs in less than a few hundred seconds and may in part be due to the reaction of NO3 with NO.
A comparative ray‐trace study of whistler ducting processes in the Earth’s plasmasphere
Authors: Gorney D. J. , Thorne R. M.
Published: February 2008

Numerical ray‐trace calculations have been performed to investigate the whistler ducting characteristics of various field‐aligned ionization density perturbations in the earth’s plasmasphere. The results indicate that field‐line curvature has a major influence on both the ducted ray trajectories and on the probability of escape during interhemispheric propagation. A specific comparison is made of the single‐ and multiplehop ducting ability of “bell‐shaped” versus “ledge‐shaped” ducts as a function of the density perturbation and invariant latitude. Modest (20%) ledge‐ and bell‐shaped perturbations, as well as a wide variety of “hybrid” profiles are capable of effective whistler ducting in middle latitudes, with ledge‐shaped profiles having considerably better multiple‐hop ducting characteristics. Furthermore, for a given duct the latitude range of starting locations from which lightning generated sferics can initially be trapped is considerably broader for ledge shaped profiles. Interhemispheric propagational losses from 20% ledge‐shaped profiles in middle latitudes are between 5‐12 db per hop compared to 8‐20 db for similar bell‐shaped profiles assuming specular reflection from the ionosphere. All transmitted downgoing rays consistently become “unducted” at altitudes near a few thousand kilometers due primarily to the ambient ionospheric topside plasma density gradients and magnetic field gradients and waves received on the ground should typically be observed at several degrees lower latitude than the ducting profile.
Pore pressure stabilization of failure in westerly granite
Authors: Martin Randolph J.
Published: February 2008

A series of constant strain rate laboratory experiments have been conducted to examine pore pressure stabilization of failure in Westerly granite. Stabilization is characterized by a gradual increase in axial displacement rate for several hundred seconds prior to failure followed by gradual, inaudible stress drop as the sample fails. In contrast, dynamic failure is characterized by a 20 second or less accelerating axial displacement followed by a sudden audible stress drop. Pore pressure stabilization was observed at ratios of pore pressure to confining pressure, λ, greater than 0.5 or so. The transition between stable and dynamic failure shifted to lower values of λ with increasing effective confining pressure and decreasing strain rate.
On the distinction between electrostatic ion cyclotron waves and ion cyclotron harmonic waves
Authors: Kintner P. M.
Published: February 2008

Two distinctly different plasma wave modes with structure related to the ion cyclotron frequency, ωci, have been detected by instruments onboard the S3‐3 satellite. The harmonic frequency structure with respect to ωci is different for each mode and the two modes exhibit different values of phase coherence. One referred to as the electrostatic ion cyclotron wave has already been discussed extensively in the literature. The other, the ion cyclotron harmonic mode, is discussed in detail here for the first time. This mode has been produced in the laboratory by a perpendicular ion beam and in fact is found to correlate with energetic ion distributions peaked near 90 degrees (ion conies) in the S3‐3 data set. The observations are compared favorably to a theory for electrostatic waves with wave vector nearly perpendicular to the magnetic field, in the presence of a perpendicular ion beam.
Volume changes in Ganymede and Callisto and the origin of grooved terrain
Authors: Squyres Steven W.
Published: February 2008

Internal melting and differentiation of Ganymede and Callisto may have caused an increase in the surface area of these bodies early in their histories of up to 5‐7%. Subsequent refreezing of internal liquid water due to solid state convection in an ice crust should not have caused significant surface area changes. Expansion due to differentiation may have caused formation of grooved terrain on Ganymede. These calculations suggest that grooved terrain formation is essentially a replacement and/or deformation process, with no more than about 15% of grooved terrain actually being new material. The absence of grooved terrain on Callisto may be due to the effects of a thicker crust and a lower expansion rate.
Geomagnetic activity at the time of heliospheric current sheet crossings
Authors: Hakamada Kazuyuki
Published: February 2008

Geomagnetic activity during three days before and after heliospheric current sheet crossings is examined. It is shown that the expression for the index
, obtained by Murayama [1979], is applicable to such geomagnetic activity, where
(in nT) and V (in km/sec) stand for the southward component of the interplanetary magnetic field and solar wind bulk velocity, respectively. The effects of
and V on AL are also examined separately. It is found that short term (∼hours) variations of AL are controlled by fluctuations of
while long term (∼days) variations of AL are controlled by V.
The Selenographical distribution of deep moonquake epicenters
Authors: Binder Alan B.
Published: February 2008

The observed selenographical distribution of the epicenters of the deep moonquakes is explained using a simple lunar model with a low Q deep interior and assuming that the number of epicenters per unit area is proportional to the tidal potential affecting the area.
An observed annual cycle in tropical upper stratospheric and mesospheric ozone
Authors: Frederick J. E. , Abrams R. B. , Dasgupta R. , Guenther B.
Published: February 2008

Analysis of more than one year of backscattered ultraviolet radiances obtained from an equatorial orbit by the Atmosphere Explorer‐E satellite reveals an annual cycle in tropical, high altitude ozone which shows no latitude dependence between 20 degrees south and 20 degrees north. The amplitude of the variation increases with altitude. In the 35 to 45 km altitude region statistics of the data suggest no variation whatsoever, while in the lower mesosphere the radiances indicate an ozone increase of 25 to 30 percent between January and July with a decrease thereafter provided the solar irradiance remained constant except for the variation with earth‐sun distance.
Paleozoic Plutonism from southern New Mexico: Evidence from the Florida mountains
Authors: Brookins Douglas G.
Published: February 2008

The pre‐Tertiary rocks of the Florida Mountains, southern New Mexico, have been previously mapped as Precambrian (Griswold, 1961) or Mesozoic (Corbitt and Woodward, 1973). Previously determined K‐Ar and Rb‐Sr mineral dates by R. E. Denison (Brookins, 1974a) range from 418 to 555 MYBP. Early attempts at using the Rb‐Sr whole rock method on weathered, surface samples (Brookins, 1974a) indicated a mix of Precambrian samples with samples which yielded apparent Paleozoic dates; these latter samples were considered unreliable because of their weathered nature. The presence of quartz syenite and syenite in addition to quartz monzonite‐granodiorite in the Floridas was confirmed however. Recently, drilling has been carried out in the Floridas and very fresh samples have been made available for study. These samples yield Precambrian dates for the quartz monzonite‐granodiorite suite, but the quartz syenites and syenites yield Rb‐Sr whole rock isochrons of 395 ± 27 MYBP and 371 ± 19 MYBP respectively. These isochrons, 8‐to‐10 data each, indicate plutonic activity in the mid‐Paleozoic in southern New Mexico. A survey of the literature and independent geochronologic work (Loring and Armstrong, 1980) suggest that Paleozoic plutonism in New Mexico may be more widespread than previously thought.
The distribution of temperature maxima for micrometeorites decelerated in the Earth's atmosphere without melting
Authors: Fraundorf P.
Published: February 2008

A simple model for the statistics of heating of micrometeorites decelerated in the earth's atmosphere without melting predicts that for 10 µm particles with thermal emissivity near 1, roughly half of those with density 1 g/cc are heated above 550°C, while half of those with density 3 g/cc are heated above 800°C. In the study of stratosphere collected interplanetary dust, the model can be helpful in identifying petrographic thermometers of the atmospheric entry process, and in understanding the most recent history of this new class of extraterrestrial material available in the laboratory.
Spatial and temporal variations in ts/tp at Monticello Reservoir, South Carolina
Authors: Rastogi B. K. , Talwani Pradeep
Published: February 2008

Following its impoundment in December 1977, induced seismicity was observed at Monticello reservoir in South Carolina. This shallow (< 2 km), low level (ML < 3.0) activity is still continuing and is confined to the immediate vicinity of the reservoir (in an area of about 5 × 10 km²). Spatial and temporal variations in ts/tp ratios were examined in detail for the period July‐September 1978. We observed two periods of precursory decrease of 6‐12% in ts/tp for ML 2.7 and 2.3 events on August 27 and September 15, 1978, respectively. A precursor time of about 15 days was observed for each of these events. During the anomalous periods, stations within about 8 km of the epicentral area (S‐P ∼ 1 sec) were associated with low ratio values, while the distant stations were associated with normal ratio values ( ∼ 1.75) suggesting that the size of the anomalous zone associated with 2.0 < ML < 3.0 earthquakes is about 4 km in radius.
A new technique for measuring tropospheric formaldehyde [CH2O]
Authors: Lowe D. C. , Schmidt U. , Ehhalt D. H.
Published: February 2008

A high performance liquid chromatographic technique has been used to determine the CH2O mixing ratio of tropospheric air. The technique has demonstrated adequate sensitivity and stability for measurements of the low CH2O mixing ratios expected at elevated altitudes. CH2O mixing ratios from a series of air samples collected at the surface around Jülich, West Germany averaged 1.3 ± 0.7 ppbv over the period August 1979 to February 1980. Air samples were also collected during several tropospheric aircraft flights up to about 5 km and CH2O mixing ratios ranged between 0.3 and 0.5 ppbv below and less than 0.1 ppbv above the inversion.
Determination of the total grain size distribution in a Vulcanian eruption column, and its implications to stratospheric aerosol perturbation
Authors: Murrow P. J. , Rose W. I. , Self S.
Published: February 2008

Grain size analysis of samples representing all sampleable portions of the airfall deposit produced by the Fuego volcano in Guatemala on 14 October 1974 form the basis for estimating the total grain size distribution of tephra from this eruption. The region enclosed by each isopach has a particular average grain size distribution which can be weighted proportionally to its percentage volume. The grain size of pyroclastic avalanche deposits produced during the eruption are also included. The total grain size distribution calculated as a sum of weighted distributions has a median grain size of 0.8∅ (0.6mm) and a sorting coefficient (σ∅) of 2.3. The size distribution seems to approximate Rosin and Rammler's law of crushing and this observation allows us to estimate that no more than 15% volume of the fine tail of the total size distribution is likely to be missing. The ash composed of these fine particles did not fall in the region of the volcano as part of the recognizable tephra blanket. The eruption column reached well into the stratosphere: heights estimated from the ground were 10‐12 km above sea level but estimated heights based on mass flux rates are higher (18‐23 km). The proportion of ash smaller than 2 µm, which could remain for substantial periods in the stratosphere, is no more than 0.8% volume of the total. It seems probable that acid aerosol particles from vulcanian type eruptions are more important to stratospheric aerosol perturbation than fine silicate ash particles by at least an order of magnitude.
Submicrosecond risetimes in lightning return‐stroke fields
Authors: Weidman Charles D. , Krider E. Philip
Published: February 2008

Measurements of lightning electric field, E, and dE/dt signatures have been made near Tampa Bay, Florida, under conditions where the lightning locations were known and where the results were not significantly affected by the response time of the measuring system or ground‐wave propagation. The fast transitions found on the initial portion of return‐stroke fields have 10‐90% risetimes ranging from 40 to 200 ns, with a mean of 90 ns. The maximum field derivatives during return strokes range from 5 to 75 V/m(µs)−1 with a mean of 29 V/m(µs)−1 when normalized to a distance of 100 km. These field risetime and derivative values suggest that return‐stroke currents contain large, submicrosecond components, and this in turn suggests that it may be necessary to reevaluate the possible effects of lightning and the performance of lightning‐protection devices in many situations.
Simultaneous wave and particle observations in the auroral kilometric radiation source region
Authors: Benson Robert F. , Calvert Wynne , Klumpar David M.
Published: February 2008

Simultaneous observations from the topside sounder and the soft particle spectrometer onboard the ISIS 1 satellite reveal that very specific conditions on the local electron density and the energetic electron distributions must both occur in the auroral kilometric radiation (AKR) source region. Such regions are associated with inverted V electron precipitation and with depletions in the local electron density. The electron velocity distribution functions obtained near the inverted V peak were found to increase near several keV energy with increasing velocity as required for plasma instability. The electron density observed near the inverted V peak was too high to support AKR for three events investigated, however, and the AKR source was identified with the edge of the inverted V where the density was low (⩽ 30 cm−3) in each case. Whereas this density depletion can extend deep into the ionosphere (∼ 1500 km altitude), the severe depletion associated with the AKR density cavity is restricted to higher altitudes (> 2750 km for an event studied in detail).
Measurements of the spectral profile of Balmer alpha emission from the hydrogen geocorona
Authors: Meriwether J. W. , Atreya S. K. , Donahue T. M. , Burnside R. G.
Published: February 2008

Instrumental improvements responsible for a factor of 25 increase in the sensitivity of the Fabry‐Perot interferometer enable us to observe for the first time the short wavelength depletion of the Balmer α spectral profile due to hydrogen escape. These results are shown to be consistent with the implications of OGO‐5 observations by Bertaux.
Association between plasma bubble irregularities and airglow disturbances over Brazilian low latitudes
Authors: Sobral J. H. A. , Abdu M. A. , Zamlutti C. J. , Batista I. S.
Published: February 2008

Meridional profiles of OI 6300 Å nightglow emission measured using a scanning photometer over Cachoeira Paulista, a low latitude station, often show propagating patches of airglow disturbances with north to south and west to east velocity components, occurring mostly in the premidnight period. 132 measurements carried out during a period of 26 months since January 1978, show significant seasonal dependence in the occurrence of these disturbances, with most of the events occurring in the spring‐summer months and with very rare occurrence during the winter solstice. The north to south propagation velocities lie in the range of 150 to 350 m/s. A case by case comparison of the occurrences of these airglow disturbances with simultaneous ionograms over Cachoeira Paulista show that almost the totality of these disturbances are accompanied by strong range type echoes in the ionograms and vice versa. These results therefore support our earlier contention that these types of airglow disturbances might be manifestations of the equatorial plasma bubbles.
Dislocation structures of olivine from Pallasite meteorites
Authors: Matsui Takafumi , Karato Shun‐ichiro , Yokokura Takanobu
Published: February 2008

Dislocation structures in olivines from three pallasite meteorites (Admire, Brenhan and Dora) were observed. Results are as follows: (1) Dislocation densities are very low (≤ 1 × 106 cm−2) compared to those of terrestrial olivine. (2) Dislocations are mostly curved. (3) Subboundaries are well developed. (4) The slip system determined from the dislocation dipole and sub‐boundaries is (010)[100]. (5) There are helical dislocations. (6) Dislocation densities and spacing of sub‐boundaries have either a power‐law relation or one characteristic of annealing. These observations all imply that the olivines from pallasites were annealed, that they have experienced high temperature deformation at low strain rate within parent bodies during the course of cooling, and that differential stresses which cause deformation can not have exceeded several times ten bars since then. Dislocations in olivine grains from pallasites are not of impact origin but are due to deformation within parent bodies.
Shallow moonquakes: Argon release mechanism
Authors: Binder Alan B.
Published: February 2008

Apollo 17 surface mass‐spectrometer observations have shown that 1027 to 1028 mol. of 40Ar are released from the moon when shallow moonquakes occur. Model calculations, based on the seismic and strain energies released by the moonquakes, the volumes of their focal zones, and the surface areas of observed shallow thrust faults, indicate that > 1.5 × 1025 to ≲ 2 × 1028 mol. of 40Ar could be released by each shallow moonquake as a result of mylomization and possible frictional melting of the rocks within a few decimeters of the newly formed parts of the fault surface. The rapid escape of this 40Ar along the fractures of the fault would produce the observed argon release event shortly after each moonquake.
An empirical relationship between the concentration of resuspended sediment and near bottom wave‐orbital velocity
Authors: Lesht B. M. , Clarke T. L. , Young R. A. , Swift D. J. P. , Freeland G. L.
Published: February 2008

Five deployments of a boundary layer probe were undertaken on the Long Island inner continental shelf between 1976 and 1978. The probe measured suspended sediment concentration and fluid velocity 100 cm above the bottom. Multivariate analysis of the data from all deployments shows that surface wave activity is the major determinant of suspended sediment concentration. Concentration is found to be proportional to the wave orbital velocity when the velocity is above a threshold value. Both the threshold value (WST) and the proportionality constant (β) seem to depend on the composition of the local sediment substrate; WST increasing with the mean size of the coarse fraction, β increasing with the amount of fine‐grained (<62 µ) material.
Ellipticity variations in Pi2 pulsations at low latitudes
Authors: Sutcliffe Peter R.
Published: February 2008

A study of the temporal variations in the horizontal plane ellipticity of Pi2 pulsations recorded at a low latitude station reveals both nocturnal and annual variations. Ellipticity decreases from positive to negative through the night; the greatest decrease occurs during November and the smallest during May. The variations exhibit trends similar to those in plasmaspheric electron density and total ionospheric electron content.
Lunar tides at meteor heights
Authors: Tsuda Toshitaka , Tanii Jun , Aso Takehiko , Kato Susumu
Published: February 2008

We determined lunar semidiurnal (M2) and diurnal luni‐solar (O1) tides of the meridional winds observed for two years between 1979 and 1980 by the Kyoto meteor radar. At 95 km altitude, the M2 and O1 tidal wind of 2.2 m/sec and 1.2 m/sec were observed. From the downward phase progression with altitude, the vertical wavelength was estimated as 60 and 25 km for the M2 and O1 component, respectively. Seasonal variation of the M2 tidal wind was detected. Lunar variation has also been detected in the mean height of meteor echoes. The amplitude for the M2 and O1 component was 0.22 and 0.18 km, with the maximum height occurring at 9.4 and 14.1 hrs lunar time, respectively.
Remanent magnetization of ash from the 18 May 1980 eruption of Mount St. Helens
Authors: Steele William K.
Published: February 2008

Ash from the 18 May 1980 eruption of Mount St. Helens deposited from air faithfully records the direction of the local geomagnetic field in eastern Washington, whereas ash settled from suspension in water in fluvial environments exhibits significant inclination and current‐rotation errors in magnetic direction similar to those reported in other subaqueously deposited sediments. The current‐rotation errors are associated with partial alignment of the major axes of magnetic susceptibility in the direction of water currents. Subaerial deposition produces strong stable remanent magnetization in ash with or without postdepositional wetting by rain.
Global simulations of the three‐dimensional magnetosphere
Authors: Leboeuf J. N. , Tajima T. , Kennel C. F. , Dawson J. M.
Published: February 2008

Global three‐dimensional computer simulations of the magnetosphere using a particle MHD code, reproduce the steady‐state Dungey magnetospheric topology in three dimensions. We observe the formation of a compression zone downstream of the tail neutral line that is probably bounded by wake shocks. This compression zone changes its cross‐section with distance downstream.
Maintenance of the shoreface by wave orbital currents and mean flow: Observations from the Long Island Coast
Authors: Niedoroda Alan W. , Swift Donald J. P.
Published: February 2008

Waves and currents were observed for a total of 36 days in August 1976 and 1977. Calculations of wave transport of sediment, using a Bagnold equation for transport and second order Stokes theory, show that wave orbital current asymmetry results in landward sediment transport in 10 m or less water depth, but does not significantly effect transport at greater depths. Calculations of sand transport using the Madsen‐Grant formulation show that during a 36 day observation period, sediment in less than 10 m of water generally moved landward into the breaker and then along coast with the wave‐driven littoral flow. The calculations show that below 10 m the generally upwelling coast‐parallel mean flow did not move sediment. However, during two days of a mild summer "northeaster" storm, a downwelling coastal jet developed, with 60 cm sec−1 maximum current. The calculations show that if this flow had been combined with the intense wave regime of the succeeding several days, sediment would have been entrained across the lower as well as the upper shoreface. Movement would have been offshore and alongshore. Such storm transport is believed to be typical of the more intense winter storms, and to be responsible for the erosional shoreface retreat that has caused up to a kilometer of shoreline retreat on the Long Island Coast in the last century.
Krypton and xenon in the atmosphere of Venus
Authors: Donahue T. M. , Hoffman J. H. , Hodges R. R.
Published: February 2008

Probable values of the mixing ratios of krypton and its isotopes on Venus by the Pioneer Venus large probe neutral mass spectrometer are reported. An upper limit to most of the xenon isotope mixing ratios is also set. Based on a 36Ar mixing ratio of 30 ppm the krypton mixing ratio is probably 47 ppb and its upper limit 69 ppb. The upper limit for Xe is 120 ppb but there is probably considerably less than 40 ppb. Atmospheric krypton and xenon on Venus exceed terrestrial values by factors of 3.5 and no more than 30, much less than the ratios for neon and argon. It appears that the noble gases on Venus have a large solar component compared to Earth and Mars.
A three dimensional MHD model of the Earth’s magnetosphere
Authors: Wu C. C. , Walker R. J. , Dawson J. M.
Published: February 2008

We have simulated the steady state magnetospheric configuration which results when solar wind plasma impinges on a magnetic dipole. In our calculation, the MHD equations were solved self‐consistently by a large scale code which employs Rusanov’s method to produce a three‐dimensional model of the magnetospheric fields and plasma. This simulation, in which the interplanetary magnetic field was assumed to be zero, reproduced many of the observed magnetospheric features including the bow shock, magnetopause and plasma sheet. In particular, the calculated magnetic field is consistent with quiet time observations. The currents in the simulated magnetosphere are remarkably similar to those from semi‐empirical magnetic field models.
Four wavelength nephelometer measurements at South Pole
Authors: Bodhaine Barry A. , Bortniak John C.
Published: February 2008

A four wavelength nephelometer was installed at South Pole station in January 1979 in order to measure the volumetric aerosol scattering coefficient during the austral winter of 1979. The monthly mean aerosol light scattering at 550 nm wavelength for May was 1.23×10−7m−1, the lowest monthly mean value ever recorded at any GMCC station. This implies a total aerosol mass loading of 39 ng m−3, in agreement with aerosol mass measurements at South Pole station. Condensation nuclei concentrations in 1979 range between monthly means of 185 cm−3 in February and 10 cm−3 in July.
Paleomagnetism of a Keweenawan age intrusive near Clam Lake, Wisconsin
Authors: Kean William F. , Swingen Regina A.
Published: February 2008

Two long cores from a magnetite‐rich gabbroic intrusion near Clam Lake, Wisconsin were studied to obtain paleopole positions to aid in determining the time of intrusion and learn more about the tectonics of the area. This intrusion was suspected to be late Precambrian in age. A.F. demagnetization above 150 oe. produced reliable remanent directions. The cores were not azimuthally oriented, therefore small circle plots were made for each sample using 12 different horizontal orientations. The best pole position was considered to be where the small circle paths crossed the Precambrian polar wander curve. This gave a normal pole at N 30° E 176° which is middle Keweenawan in age. The average inclination and declination for 14 of the 18 core sections was 35° and 288° respectively, which is consistent with aeromagnetic maps of the area. The 35° inclination is consistent with most middle Keweenawan rocks of the area, after they have been corrected for a 10° ‐ 30° tilt. This suggests that the Clam Lake area was not tilted after intrusion. Basalt dikes in the gabbro gave consistently lower inclinations, which suggest a late Keweenawan time for their formation.
Estimates of the north‐south electric field component in the magnetotail low latitude boundary layer
Authors: Candidi Maurizio , Orsini Stefano
Published: February 2008

The measurements of O+ ions drift velocity in the magnetotail boundary layer are used to infer the North‐South Ez component of the local electric field. It is shown that Ez is generally a substantial component of the field and that it reverses its sign from the dawn to the dusk side of the northern magnetotail between XSM=−15 RE and XSM=−23 RE.
The effect of size on mechanical properties of rock
Authors: Brace W. F.
Published: February 2008

Strength of certain soft rocks decreases about tenfold as specimen size reaches around 1 meter; at still larger sizes, it appears to remain constant. Hard rocks have not been tested over this range of sizes, so their size effect is unknown. Elastic modulus of unfractured rocks is only very slightly dependent on specimen size up to a meter. However, large fractured samples may be five to ten times more compliant than small intact samples. Friction is also size‐dependent, although observations are conflicting.
Effect of size on fluid movement in rock fractures
Authors: Witherspoon Paul A.
Published: February 2008

Laboratory studies on fluid flow in single fractures in rock samples up to a meter in size suggest that there is a definite problem of scale. Two such studies have been reported, but the results are not consistent. The seemingly contradictory results may simply be a manifestation of the effects of fracture surface roughness. A basic problem in attempting to understand the physics of fluid flow in fractures is that of understanding the effects of surface roughness. The investigations that are envisioned to attack this problem will only be possible on rock samples that are much larger than the conventional size.
Evidence of a velocity shear in bulk plasma motion associated with the post‐sunset rise of the equatorial F‐layer
Authors: Tsunoda R. T. , Livingston R. C. , Rino C. L.
Published: February 2008

Using the east‐west drift of equatorial spread‐F (ESF) irregularities as tracers for horizontal bulk plasma motion, we show that a velocity shear (with altitude) in east‐west plasma drift exists in the nighttime equatorial F‐layer. When combined with incoherent‐scatter measurements of the vertical motion of the F‐layer, we find evidence that the two‐dimensional plasma flow pattern in the F‐region around E‐region sunset resembles a vortex. The velocity vortex is attributed to (1) a velocity shear that is set up by the F‐region dynamo that begins to function around E‐region sunset, and (2) the postsunset rise of the F‐layer. The existence of a velocity shear verifies the importance of the eastward neutral wind and F‐region dynamo in nighttime equatorial plasma electrodynamics, and allows new interpretation for ESF generation processes.
Correlation of the cosmic‐ray intensity with solar‐terrestrial parameters
Authors: Jokipii J. R.
Published: February 2008

Shea and Smart (1981) have shown that the correlation between the Mt. Washington neutron monitor counting rate and the geomagnetic aa index changes significantly from the eleven‐year period centered on one solar minimum to the next such period. They suggested that this may be a manifestation of cosmic‐ray drift in the interplanetary magnetic field. This Letter reports the results of numerical simulations of cosmic‐ray modulation, including drift, which verify that drifts can indeed produce the sense of the observed effect. Perturbations in the heliospheric equatorial regions affect galactic cosmic rays observed near the equator more effectively if the northern hemisphere heliospheric magnetic field is inward than if it is outward. Perturbations in K⊥ are substantially more effective than perturbations in the solar wind velocity or in K∥.
A note on the location of the stagnation point in the magnetosheath flow
Authors: Russell C. T. , Zhuang H‐C. , Walker R. J. , Crooker Nancy U.
Published: February 2008

Observational and theoretical investigations indicate that the shape of the magnetosphere is nearly symmetric about the plane defined by the aberrated solar wind velocity and the earth's magnetic dipole axis. Nevertheless, many phenomena such as magnetic pulsations and geomagnetic activity seem to indicate that the effective solar wind arrival direction is perhaps 15° to the dawn side of noon. This apparent paradox may have a simple resolution since it can be shown that the location of the stagnation point in the magnetosheath flow is shifted towards dawn by MHD effects not included in the simple gasdynamic model of the solar wind interaction. The shape of the magnetosphere is little affected by the inclusion of these MHD effects. However, the size of the stagnation point shift is very sensitive to the Alfven Mach number and can only account for the largest reported shifts (∼15°) at low Mach numbers (≲3.5).
Electromagnetic active source sounding near the East Pacific Rise
Authors: Young Peter D. , Cox Charles S.
Published: February 2008

An active source electrical conductivity sounding was carried out near the East Pacific Rise at 21°N. The average electrical conductivity from 2 km beneath the seafloor into the upper mantle was found to be about 0.004 S/m. There is no evidence of fully molten magma at a distance of 7 km from the spreading axis. The inferred conductivity with depth of the crustal rock is consistent with Brace’s model of connected, seawater filled pores in rocks heated from beneath.
Neon composition in solar flares
Authors: Venkatesan T. R. , Nautiyal C. M. , Rao M. N.
Published: February 2008

To examine whether the long‐term averaged solar flare Ne is "planetary" type, as observed in contemporary solar flares, we have studied etched feldspar separates of several lunar soils and three samples from different depths of two well‐documented lunar rocks. Our results of noble gas elemental and isotopic ratios suggest that the long‐term average solar flare Ne composition is more similar to "solar" type than the "planetary" type.
Mass spectrometric detection of precondensation nuclei at the Artic summer mesopause
Authors: Björn Lennart G. , Arnold Frank
Published: February 2008

A positive ion composition measurement at the summer, high latitude mesopause in the presence of noctilucent clouds has revealed the existence of very massive positive ionospheric ions. The ions were assigned to be proton hydrates of which the heaviest ones contained up to 20 water molecules. These most massive ions were concentrated in a thin layer at an altitude of 90 km. A likely explantation of the existence of so heavy ionospheric ions is a strong local cooling within the layer in combination with a very low electron concentration. In spite of the high altitude of detection of these ions it is conceivable that they represented condensation nuclei eventually leading to the formation of visible notilucent clouds.
Slumping and ejecta sliding accompanying some 10‐ton cratering events
Authors: Gaffney Edward S.
Published: February 2008

Both inward slumping and outward ejecta sliding are inferred to have occurred in four 10‐ton explosive cratering events in Gulf coastal plain sediments. These inferences result from a comparison of displacements obtained by integration of real‐time velocity data from subsurface gauges with displacements based on post‐shot surveys. The slumping did not occur immediately after crater excavation; it was delayed by more than 5 seconds but less than one day. This delay probably resulted from slow recompaction and resaturation of the ejecta and crater walls on a scale of minutes to hours after the excavation and attendant dilation of the media. Ejecta sliding, probably at a few meters per second, apparently moved concrete blocks on the surface up to 2 meters outward relative to gauges buried at the same initial range. The ejecta sliding was not uniform and may occasionally have included portions of the underlying ground.
Problems with the N2+ + O → NO+ + N reaction in aurora
Authors: Swider William , Narcisi Rocco S.
Published: February 2008

An effective rate coefficient for N2+ + O → NO+ + N which increases with altitude is deduced from an analysis of the auroral ion composition measured between 120 and 200 km over Poker Flat, Alaska on March 6, 1981. This result may be interpreted in terms of a rate coefficient with a positive temperature dependence, roughly k3 ≃ 1.5 × 10−10 (Ti/300)0.6 cm³ s−1 over a 300‐1600°K temperature range. Other interpretations are discussed, including the possibility that the N2+ ions are vibrationally excited.
Influence of gravity field uncertainties on the results from Pogo and Magsat geomagnetic surveys
Authors: Taylor P. T. , Schanzle A. F. , Jones T. L. , Langel R. A. , Kahn W. D.
Published: February 2008

Previous studies have shown several instances where airborne magnetic data, extrapolated to satellite altitude, differ from data obtained by the POGO and MAGSAT satellites. In an effort to explain this difference we have examined errors in the coefficients representing the Earth’s gravitational field which could produce satellite positional variations and therefore would account for the observed differences. Our results indicate that while the magnitude of the orbital errors are in a range that could account for the amplitude of these observed variations, the frequency of the quasi‐periodic orbital error is too large to explain the localized nature of the observed differences. Hence, uncertainties in the coefficients of the gravity model cannot explain the observed phenomenon. In a separate, but related computation, large crustal gravity anomalies have also been examined and shown to be insufficient to produce the desired magnitude of orbital perturbation.
Space chamber experiments of Ohmic heating by high power microwave from the solar power satellite
Authors: Kaya Nobuyuki , Matsumoto Hiroshi
Published: February 2008

It is quantitatively predicted that a high power microwave from the Solar Power Satellite (SPS) nonlinearly interacts with the ionospheric plasma. The possible nonlinear interactions are ohmic heating, self‐focusing and parametric instabilities. A rocket experiment called MINIX (Microwave‐Ionosphere Nonlinear Interaction Experiment) has been attempted to examine these effects, but is not reported here. In parallel to the rocket experiment, a laboratory experiment in a space plasma simulation chamber has been carried out in order to examine ohmic heating in detail and to develop a system of the rocket experiment. Interesting results were observed and these results were utilized to revise the system of the rocket experiments. A significant microwave heating of plasma up to 150 % temperature increase was observed with little electron density decrease. It was shown that the temperature increase is not due to the RF breakdown but to the ohmic heating in the simulated ionospheric plasma. These microwave effects have to be taken into account in the SPS Project in the future.
Magnetic field and plasma wave observations in a plasma cloud at Venus
Authors: Russell C. T. , Luhmann J. G. , Elphic R. C. , Scarf F. L. , Brace L. H.
Published: February 2008

Pioneer Venus magnetic field and plasma wave data are examined in a particularly clear example of a plasma cloud above the Venus ionosphere. The magnetic configuration is suggestive of acceleration of the plasma cloud by magnetic tension. If the plasma is at rest at the subsolar point, it could be accelerated to ∼90 km/sec by the observed stress at the location of the measurement. This far exceeds the escape velocity and suggests that plasma clouds do form a significant loss mechanism for the Venus ionosphere but do not necessarily indicate that the plasma cloud is detached from the ionosphere proper. The plasma cloud is accompanied by strong plasma wave activity and is significantly hotter than the ionospheric plasma encountered later on the same pass. We estimate a loss rate of the order of 2 × 1025 ions per second during this event. The geometry suggested by these observations is one of a ridge of dense cold plasma starting in the subsolar regions and flowing over the poles of the planet. Thus, these plasma clouds may be the planetary analogue of cometary tail rays.
Method for automatically rounding data on the Wang 2200 in basic computer language
Authors: Sibley Scott F.
Published: February 2008

The method described permits any set of numbers within an allowable range to be rounded to any number of significant figures. This is accomplished by generation of an array (rounding position) data bank, which is unique for each combination of the following variables: (1) Chosen decimal position; (2) number range of the number to be rounded; and (3) number of significant figures to which this number is to be rounded. It is especially useful as a subroutine in programs that generate large quantities of figures (such as reserve or resource tonnages) that require rounding.
Impulsive plasma transport through the magnetopause
Authors: Heikkila Walter J.
Published: February 2008

A localized plasma cloud of magnetosheath plasma with some excess momentum is assumed to distort the surface of the magnetopause, and its associated currents, inducing an electric field that can be of the order of 1mV/m. This induction electric field by itself is just what is needed so that the plasma can follow the moving magnetopause. A normal component of the magnetic field Bn through the magnetopause will permit a small field‐aligned polarization current; this current will deliver charge that will create an electrostatic field. The normal component of the total electric field will be reduced (perhaps to zero) while the tangential component will be enhanced. This enhancement will allow the cloud to continue moving toward the moving magnetopause. At the same time the plasma particles will be slightly energized, and being propelled by the mirror force −μ∇B they will become more field aligned as they go through the magnetopause. Energy for these events comes from the excess momentum via the induction electric field. Once inside the moving magnetopause, the cloud can go across field lines (either open or closed) until it loses its excess momentum. A cross‐sectional slice of the plasma cloud (at the inner edge of the magnetopause current) acts as a generator; the whole process can be regarded as an electric circuit, with a generator preceding the load, the trailing portion of the current. Losses of particles, momentum, and energy will occur; the mechanism described is one possible form of “viscous interaction” between the shocked solar wind and the magnetosphere. The total amount of power going into the plasma is likely to be much less than 5×1011 watts, and may even be negative, indicating the futility of searching for dissipation of this magnitude.