bluuebunny/crossref_metadata_2025 huggingface dataset:
Apparent solar cycle influence on long‐period oscillations in stratospheric zonal wind speed
Authors: Nastrom G. D. , Belmont A. D.
Published: February 2008

The amplitude of the semiannual oscillation in stratospheric zonal wind speed, from rocketsonde data for 1960‐1978, appears to vary as a function of the solar cycle. The apparent solar cycle modulation influence is present at all latitudes, and is largest near the stratopause. The amplitude of the semiannual wave decreases up to 50% at all latitudes from solar maximum to minimum. During 1950‐1978, the period of the tropical quasi‐biennial oscillation at 30 mb varied inversely with the solar cycle. These results indicate care must be taken to consider solar‐cycle effects when comparing results for different periods of record or when estimating long‐term trends.
Simultaneous mixing ratio profiles of stratospheric NO and NO2 as derived from balloon‐borne infrared solar spectra
Authors: Blatherwick R. D. , Goldman A. , Murcray D. G. , Murcray F. J. , Cook G. R. , VanAllen J. W.
Published: February 2008

Balloon‐borne infrared solar spectra at ∼0.02 cm−1 resolution obtained during sunset are used for the derivation of simultaneous vertical mixing ratio profiles of NO and NO2. A simplified photochemical model for the diurnal variation of NO is included in the analysis.
The dependence on zenith angle of the strength of 3‐meter equatorial electrojet irregularities
Authors: Ierkic H. M. , Fejer B. G. , Farley D. T.
Published: February 2008

Radar measurements in Peru were used to deduce the zenith angle dependence of the scattering cross section of plasma irregularities generated by instabilities in the equatorial electrojet. The irregularities probed by the 50 MHz Jicamarca radar had a wavelength of 3m. The cross section for the type 2 irregularities was isotropic in the plane perpendicular to the magnetic field, while the cross section for the stronger type 1 irregularities varied with zenith angle at a rate of approximately 0.3 dB/degree; the horizontally traveling waves were more than 100 times stronger than those traveling vertically.
The location of the dayside ionopause of Venus: Pioneer Venus Orbiter Magnetometer observations
Authors: Elphic R. C. , Russell C. T. , Slavin J. A. , Brace L. H. , Nagy A. F.
Published: February 2008

The location of the dayside Venus ionopause, as observed by the Pioneer Venus Orbiter, is shown to depend on the magnetic pressure in the shocked, highly compressed solar wind plasma just outside the ionopause. Assuming a balance exclusively between this external magnetic pressure and internal ionospheric thermal pressure, invariance of ionospheric conditions, and an isothermal ionosphere, it is possible to determine pressure scale heights for various solar zenith angle intervals. These scale heights yield ionospheric temperatures which agree with direct measurements obtained independently. Not surprisingly, the average ionopause altitude is higher near the terminator, where the average external magnetic pressure is lower. The near‐terminator ionopause has much greater positional variability than that at lower solar zenith angles; this appears to be due principally to concomitant variations in the external magnetic pressure, presumably related to solar wind pressure changes.
Variation of the average ‘freezing‐in’ temperature of oxygen ions with solar wind speed
Authors: Ogilvie Keith W. , Vogt C.
Published: February 2008

Observations of the average Oxygen ionization equilibrium as a function of speed of the solar wind are presented. At low solar wind speeds they indicate a coronal temperature at the freezing‐in point of 1.6 ± 0.2 × 106 °K. At speeds above 450 km sec−1 the apparent temperature starts to rise rapidly. This rise is tentatively interpreted in terms of a lack of thermodynamic equilibrium in the source region.
Influence of the equatorial irregularities and precipitations in the South Atlantic Magnetic Anomaly on the generation of auroral‐type plasma instabilities
Authors: Prange Renée , Bruston Paul
Published: February 2008

Observational evidence of upward field‐aligned beams in the keV range has been obtained in the sub‐equatorial ionosphere above South America. These events can be related to coupled magnetic and ionospheric activity (magnetic storm, ionospheric irregularities). This result is in opposition with the current theory of the low‐latitude ionosphere. Its interpretation must assume that conditions exist for the growth of plasma instabilities. This implies a low plasma density, a close coupling between the ionosphere and the magnetosphere, and field‐aligned currents. Such suitable conditions have independently been observed in ionospheric irregularities (density, currents) or during magnetic storms (energetic particle precipitation) or they are deduced from the structure of the Anomaly (field‐aligned currents). This allows us to suggest that the South Atlantic Anomaly sometimes compares to the auroral oval and may develop some current‐driven plasma instabilities.
Remarkable anisotropic cosmic‐ray intensity oscillation
Authors: Duggal S. P. , Pomerantz M. A. , Tsao C. H.
Published: February 2008

A large cosmic ray intensity wave in which a single oscillation of the galactic flux with a peak‐to‐peak amplitude of about 4% and a period of approximately 27 hours, occurred on October 27‐28, 1977. This unusual intensity profile was not associated with a classical Forbush decrease. Harmonic analysis in Universal Time of data from a global distribution of stations revealed that in each case the diurnal vector on October 27 differs significantly from those on other days before and after the event. Furthermore, the amplitude of the wave follows the relationship R1(i) = Aeαμ(i) where A and α(=1) are constants and μ(i) in the cosine of the angle between the direction of anisotropy and the asymptotic direction of viewing. The mechanism which produced this unusual oscillation is not yet understood.
Seasonal variability in emission of nitrous oxide from soil
Authors: Bremner J. M. , Robbins S. G. , Blackmer A. M.
Published: February 2008

Seasonal variability in emission of nitrous oxide (N2O) from soil was studied by monitoring N2O emissions from six Iowa soils for 12 months (mid‐April, 1979 to mid‐April, 1980). The soils studied were representative of soils used extensively for corn and soybean production in north‐central Iowa. They had been planted to soybeans and had received no N fertilization. The amounts of N2O‐N evolved from these soils in 12 months ranged from 0.34 to 1.97 kg ha−1 and averaged 1.20 kg ha−1. A substantial proportion (average, 67%) of the N2O evolved in 12 months was produced during the summer months of the study period, whereas only a small proportion (average, 2%) was produced during the winter months. The corresponding proportions for the spring and fall months were 18% and 13%, respectively.
The effects on the Earth's magnetotail from shocks in the solar wind
Authors: Lyon John , Brecht Stephen H. , Fedder Joel A. , Palmadesso Peter
Published: February 2008

A new, minimally diffusive MHD computer code has been used to simulate the time‐dependent, 2D interaction of the solar wind with the earth’s magnetosphere. The equilibrium with a simulated unmagnetized solar wind shows the basic features of the magnetosphere: bow shock, magnetopause, and long magnetotail. A simulated shock in the solar wind shows the presence of shock focussing in the midplane of the magnetotail. This focussing can be important in the energy budget of the plasma sheet and may have an important role in the initiation of substorms.
Power line radiation: Possible evidence of Van Der Pol oscillations in the magnetosphere
Authors: Lashinsky H. , Rosenberg T. J. , Detrick D. L.
Published: February 2008

We show that the principal observational features of power line radiation in the magnetosphere can be described as a van der Pol oscillation subject to incomplete entrainment by an externally injected signal. The nonlinear mechanism is referred to as "periodic pulling" and has been observed in laboratory low‐temperature plasma experiments.
Carbon dioxide measurements in the stratosphere
Authors: Mauersberger K. , Finstad R.
Published: February 2008

A mass spectrometer experiment for the analysis of minor constituents in the stratosphere has been flown successfully four times from Palestine, TX on board a balloon gondola. The carbon dioxide mixing ratio, which shows unexpectedly large variations in the stratosphere, reached 400 ppm in one particular night flight. This is about 20% higher than the ground value. Evidence is presented that the experiment performed well during each of the balloon flights. The isotopic ratio 12C/13C was measured and found in good agreement with previous air analyses showing a depletion of 13C.
Sources of fatty acids in Lake Michigan surface microlayers and subsurface waters
Authors: Meyers Philip A. , Owen Robert M.
Published: February 2008

Fatty acid and organic carbon contents have been measured in the particulate and dissolved phases of surface microlayer and subsurface water samples collected from Lake Michigan. Concentrations are highest close to fluvial sources and lowest in offshore areas, yet surface/subsurface fractionation is lowest near river mouths and highest in open lake locations. These gradients plus accompanying fatty acid compositional changes indicate that river‐borne organic materials are important constituents of coastal Lake Michigan microlayers and that sinking and turbulent resuspension of particulates affect surface film characteristics. Lake neuston and plankton contribute organic components which partially replace potamic materials removed by sinking.
Streaming energetic electrons in Earth's magnetotail: Evidence for substorm‐associated magnetic reconnection
Authors: Bieber J. W. , Stone E. C.
Published: February 2008

This letter reports the results of a systematic study of streaming > 200 keV electrons observed in the magnetotail with the Caltech Electron/Isotope Spectrometers aboard IMP‐7 and IMP‐8. A clear statistical association of streaming events with southward magnetic fields, often of steep inclination, and with substorms as evidenced by the AE index is demonstrated. These results support the interpretation that streaming energetic electrons are indicative of substorm‐associated magnetic reconnection in the near‐earth plasma sheet.
VHF‐radar measurements of dynamical processes in the stratosphere and mesosphere
Authors: Rüster R. , Czechowsky P. , Schmidt G.
Published: February 2008

Radar observations in the stratosphere and mesosphere have been carried out during a minor stratospheric warming in February 1980 using the SOUSY‐VHF‐Doppler‐Radar (Germany). Enhanced echoes have been received from the stratosphere up to an altitude of about 36 km and from the mesosphere in the height range between 58 and 96 km. Aspect sensitivity has been observed at stratospheric heights, where the signal power can decrease by 10 dB between the vertical and 7° off‐vertical directions. No such effect has been observed in the mesosphere. The background wind speed and the wind direction have been deduced from Doppler measurements made in three different beam directions. The observed 3‐hour average wind speed in the stratosphere reaches a maximum of 60 m s−1, while that in the mesosphere reaches 40 m s−1. In particular, quasi‐periodic signal power variations, which are associated with vertical velocity oscillations at periods of about 12 to 15 min, have been observed in the mesosphere.
Kinetic energy density and diamagnetic effects during plasma injection events
Authors: Gendrin Roger
Published: February 2008

A magnetoplasma in which energetic particles are injected is considered. The laws which govern the magnetic induction, the magnetic field and the kinetic energy density of the particles are given. It is shown that whereas the beta of the plasma can reach very high values, the perpendicular kinetic energy density cannot exceed a certain critical value Wc which is equal to (11.6/L)6 keV.cm−3 in the magnetosphere and which is of the order of 1 keV.cm−3 in the tail.
A search for a seamount charted near the historical axis of the Yucatan Current
Authors: Maul George A. , Hindle Patrick S.
Published: February 2008

The existence of an 8 fathom (15 m) shoal charted near 23°N, 86°W, a deep water position which is in the vicinity of the Yucatan Current's historical axis, was investigated using in situ and remotely sensed data. Satellite visible data (0.4 µm ‐ 0.7 µm) were used to search for bottom reflections as well as topographically induced sea surface reflection patterns; no evidence was found in either technique. Satellite infrared data (10.5 µm ‐ 12.5 µm) and shipboard bathythermograph data were used to search for a thermal manifestation of turbulence downstream of 23°N, 86°W; again no evidence was found. The satellite infrared data were also used to identify water masses in the bathymetric survey area for the purpose of defining echo sounding correction zones. Corrected echo soundings in the vicinity of 23°N, 86°W vary about 2% in cross‐line comparisons but show no soundings less than 900 m.
Possible terrestrial volcanic occurrences of gas clathrate hydrates
Authors: Gaffney Edward S.
Published: February 2008

On the basis of the thermodynamic stability of hydrates of SO2, H2S and CO2, it is suggested that those compounds may be found in some terrestrial volcanic environments. Hydrates of SO2 and H2S may be found in low‐temperature fumaroles, especially where surrounding rocks are below 0°C. Such situations could occur at high altitudes and/or high latitudes. Hydrates of H2S, SO2, and CO2 may be found on grain surfaces and in pore spaces of pyroclastic or other material overlying gas sources where proper conditions prevail, such as pore pressure equal to overburden pressure. For H2S, such deposits can occur with mean surface temperatures as high as 20°C. Submarine volcanism could give rise to stable submerged hydrate occurrences analogous to both the above occurrences.
Measurement of formaldehyde in clean air
Authors: Neitzert Volker , Seiler Wolfgang
Published: February 2008

A method for the measurement of small amounts of formaldehyde in air has been developed. The method is based on the derivatization of HCHO with 2.4‐Dinitrophenylhydrazine, forming 2.4‐Dinitrophenylhydrazone, measured with GC‐ECD‐technique. HCHO is preconcentrated using a cryogenic sampling technique. The detection limit is 0.05 ppbv for a sampling volume of 200 liter. The method has been applied for measurements in continental and marine air masses showing HCHO mixing ratios of 0.4 ‐ 5.0 ppbv and 0.2 ‐ 1.0 ppbv, respectively. HCHO mixing ratios show diurnal variations with maximum values during the early afternoon and minimum values during the early morning. In continental air, HCHO mixing ratios are positively correlated with CO and SO2, indicating anthropogenic HCHO sources which are estimated to be 6‐11 × 1012g/year−1 on a global scale.
Acid rain: Some preliminary results from global data analysis
Authors: Sequeira R.
Published: February 2008

Preliminary results of an analysis of global precipitation data from WMO (World Meteorological Organization) stations suggest that even remote maritime baseline stations, far removed from major continents, could become predisposed to acid rain if there is a deficiency of non‐marine calcium relative to non‐marine sulfate. The regional stations show greater complexity than the baseline stations in their precipitation chemistry. The overall results of this analysis suggest that not all non‐marine sulfate and nitrate in precipitation could be present as acid.
Upper limits for X ‐ ray and energetic neutral particle emission from Jupiter: Voyager‐1 results
Authors: Kirsch E , Krimigis S. M. , Kohl J. W. , Keath E. P.
Published: February 2008

The x‐ray sensitivity of the low energy proton channels in the Low Energy Charged Particle (LECP) experiment and its directional measurements are used to determine whether x‐rays from Jupiter can be recognized as additional flux above background as Voyager 1 approached the planet. Between ∼230 and ∼100 RJ a statistically significant count rate was detected which we interpret as x‐rays and/or neutral particles. The upper limit for x‐rays, related to earth‐based measurements is ≤ 1.3 × 10−4 photons/cm² sec keV in the energy range 14 to 31 keV. Such an x‐ray flux leads to estimates of precipitating electrons over the Jovian polar caps which are 200 times larger than over observed electron fluxes in the Io plasma torus. The same upper limit corresponds to ≤ 4 × 10−2 neutral particles/cm² sec keV at 100 RJ distance from Jupiter. We favor the neutral hypothesis, and estimate that it represents a loss of ≤ 1025 atoms/sec, i.e. < 0.05% of the atoms generated by Io’s volcanoes.
A high time resolution study of interplanetary parameter correlations with AE
Authors: Baker D. N. , Hones E. W. , Payne J. B. , Feldman W. C.
Published: February 2008

Using the earth‐orbiting spacecraft IMP‐8, we have performed a high time‐resolution (2.5‐min) study of the linear cross‐correlations of a quantitative indicator of magnetospheric substorm activity, the auroral electrojet (AE) index, with several interplanetary (IP) parameters. The present study includes all available satellite data (from an eight‐month period) rather than selecting a small number of substorm events, or a relatively small number of chosen days. Prior published studies have suggested that geomagnetic activity is related to a variety of solar wind parameters: solar wind speed (V); north‐south magnetic field component (Bz); total interplanetary magnetic field (IMF) strength (B); and various combinations of these parameters. Very recently, a new parameter, ϵ(= VB² sin4(θ/2)ℓo²), has been suggested as a superior predictor of substorm activity. The other major preferred correlator with geomagnetic activity is VBs, where Bs is the southward (Bz < 0) component of the IMF. Substantial discussion has ensued as to which parameter is the "best" predictor of substorm activity. The present non‐selective, high‐resolution analysis reveals that VBs generally reaches a higher peak correlation than ϵ (0.6 vs 0.54). Both parameters reach a peak correlation at the same lag time (with AE lagging the IP parameters by ∼40 min.), but VBs also appears to have a preferable qualitative lag profile shape for AE prediction purposes.
Optical search for lightning on Venus
Authors: Borucki William J. , Dyer John W. , Thomas George Z. , Jordan Jane C. , Comstock David A.
Published: February 2008

Electrical signals attributed to lightning events on Venus have been observed by instruments aboard Veneras 11 and 12 [Ksanfomaliti, 1980] and aboard the Pioneer Venus Orbiter [Taylor et al., 1979]. This paper reports the results of a search for optical pulses from the dark side of Venus made with the star sensor aboard the Pioneer Venus Orbiter. A comparison of both the frequency and amplitude distributions of received pulses with those of control experiments in which the star sensor observed deep space showed no statistically significant differences. Based on observations made during orbits 300 through 345, an upper limit of 30 flashes/km²/yr has been derived for the average lightning frequency on the dark side of Venus. This value assumes that the amplitude distribution of lightning and the attenuation of the optical pulse by clouds on Venus are not substantially different from that occurring on Earth.
Solar wind energy and electric field transfer to the Earth's magnetosphere via magnetopause reconnection
Authors: Gonzalez W. D. , Gonzalez A. L. C.
Published: February 2008

Some general expressions for the convection and parallel electric fields as well as for the energy transfer, due to magnetopause reconnection, are derived using a nose—reconnection model that takes into account the presence of the clefts. For the case of equal geomagnetic and magnetosheath field amplitudes, the expression for the power dissipated by the convection electric field reduces to the substorm parameter ε widely discussed in the recent literature. This result suggests that magnetopause reconnection is defined at the nose with a tilted reconnection line, but that the convection electric field is related only to the dawn‐dusk component of the reconnection electric field, as defined at high latitudes (clefts).
Correlative study of thermospheric gravity waves and tropospheric vorticity area index
Authors: Chiu Y. T. , Sharp L. R.
Published: February 2008

Based on the occurrence frequency of wave‐like structures in 23,691 individual measurements of thermospheric density, we demonstrate that there is no significant hemispherical correlation between satellite‐measured thermospheric wave‐like structures and the tropospheric vorticity area index in the epoch 1974‐1976. However, in the northern polar zone, (60°‐90°) N, wave occurrence frequency is greater for large values of the 500 mb vorticity area index.
Permeability and strength of San Andreas Fault gouge under high pressure
Authors: Morrow C. , Shi L. Q. , Byerlee J.
Published: February 2008

The permeability and strength of San Andreas fault gouge from the Cienega Valley was measured under confining pressures up to 2 kbar. The gouge was composed almost entirely of clay minerals, predominantly montmorillonite and mixed‐layer clays. Permeabilities ranged between 1 and 10 nanodarcies for confining pressures of a few hundred bars to 1 kbar, and less than 1 nanodarcy for pressures greater than 1 kbar. Permeability was sensitive to confining pressure and differential stress, but did not depend significantly on accumulated strain.

The low strength of saturated clay is often attributed to the buildup of excess pore pressure as the clay is stressed. These experiments, performed under drained conditions where excess pore pressure was not created, suggest that loosely bonded interlayer water in the hydrated clays can generate a pseudo‐pore pressure that serves to lower the strength of the gouge.
A note on a random stress model for seismicity statistics and earthquake prediction
Authors: Caputo Michele
Published: February 2008

Some of the results of the paper by von Seggern (1980), concerning the reddening of the wavenumber spectrum of the stress difference over the fault as the main shock approaches, depend on an assumption on the coefficient c of the relation log M0 = d + cM.

It is shown here that, at least in California, the reddening of the spectrum of a vertical section of the fractal surface (Mandelbrot 1977) begins with the aftershocks sequence, as suggested by von Seggern (1980) but the normal state (k−2, k is the wavenumber) is in the period between aftershocks and the foreshock and, because of the reddening of the spectrum, it is followed by the abnormal state (k−3) associated to the foreshock sequence. Then the major shock introduces a disorder into the local stress field and gives rise to very irregular zeroset areas with "antipersistent" fractal function, with k−0.5 to k−1.4, of the aftershock sequence. At this stage the cycle starts again with the reddening of the power spectrum. In other words there is a reddening which begins with the aftershock sequence, but with k−0.5 to k−1.4 and it ends with the foreshock sequence with k−3.

The statistical analysis of fifteen sequences of earthquakes is also presented and it is suggested that the change in the density distribution function of the stress drop may be an indicator of the preparatory phase of large earthquakes.
Saturn's magnetic field and dynamo theory
Authors: Todoeschuck John P. , Crossley David J. , Rochester Michael G.
Published: February 2008

Observations have shown that Saturn's magnetic field is remarkably axisymmetric and strongly dipolar. On reviewing three possible explanations for the field generation process we view a Braginskii nearly axisymmetric dynamo model as compatible with both the tilt angle and power requirements in a large Saturnian core. If the core is sufficiently small then a mean field dynamo becomes a more likely candidate, whereas if both these models fail an axisymmetric dynamo based on compressible flow may be possible.
Potential role of CS2 photooxidation in tropospheric sulfur chemistry
Authors: Wine P. H. , Chameides W. L. , Ravishankara A. R.
Published: February 2008

Electronically excited CS2 (CS2*) is found to be rapidly produced in the troposphere from the absorption of solar photons by ground state CS2 molecules. The chemical reaction of CS2* with O2 can, if the CS + SOO yield is greater than 0.01, remove tropospheric CS2 on a time scale of one or two weeks. Assuming a ground level background CS2 concentration of 20 pptv and an OCS lifetime of 1 year, calculations indicate that this photooxidation mechanism can be a major source of tropospheric OCS but only a minor source of SO2.
Estimation of surface temperature variations due to changes in sky and solar flux with elevation
Authors: Hummer‐Miller Susanne
Published: February 2008

Sky and solar radiance are of major importance in determining the ground temperature. Knowledge of their behavior is a fundamental part of surface temperature models. These two fluxes vary with elevation and this variation produces temperature changes. Therefore, when using thermal‐property differences to discriminate geologic materials, these flux variations with elevation need to be considered. From a representative set of field observations, it was found that flux variations with elevation can cause changes in the mean diurnal temperature gradient from −4° to −14°C per km evaluated at 2000 m. Changes in the temperature‐difference gradient of 1°‐2°C per km are also produced which is equivalent to an effective thermal‐inertia gradient of 100 W s1/2 m−2 K−1 per km. Thus, exposed bedrock on topographic ridges will appear to have a lower thermal inertia due to the additional effect.
General characteristics of strain relaxation: A note on sample preparation for large‐scale tests
Authors: Engelder Terry
Published: February 2008

Overcoring and large block tests indicate that intact rocks are disturbed upon removal from outcrops so that their laboratory properties are not the same as their in situ properties. The disturbance occurs during strain relaxation for which there are general characteristics as listed in this note.
High temperature triaxial‐torsional testing machine for concrete and rock
Authors: Bažant Zdeněk P. , Hess John D. , Meiri Samuel
Published: February 2008

The purpose and design of a novel high‐temperature triaxial‐torsional testing machine for concrete and rock is described. The temperature range is up to 600°C, the maximum axial load is 5 MN, the maximum confining pressure is 140MPa and the maximum torque is 5555 NM. The testing chamber is cylindrical with a diameter 241 mm and length 686 mm. The machine will be used for testing concrete under conditions of nuclear reactor accidents, as well as for the development of general constitutive relations for solid or cracked concrete and rock.
Paired electrostatic shocks
Authors: Temerin M. , Boehm M. H. , Mozer F. S.
Published: February 2008

Examination of 21 paired electrostatic shocks from a portion of the S3‐3 satellite data set has shown that in 20 cases the electric field in the equatorward half of the paired shock pointed poleward while the electric field in the poleward half of the paired shock pointed equatorward. At the same time the electron, ion, and wave data indicated the presence of an electric field parallel to the magnetic field in the region between the paired shocks. This parallel electric field was at an altitude below that of the satellite and pointed out of the ionosphere so as to accelerate ions upward. A comparison of the potential across the electrostatic shock and the energy of the corresponding ion beam at the energy of maximum flux gives reasonable agreement. This provides convincing evidence that the potential contours associated with paired electrostatic shocks close across the magnetic field to produce the auroral electron acceleration responsible for inverted‐V particle distributions and auroral arcs.
Propagation of low energy solar electrons
Authors: Anderson K. A. , McFadden J. P. , Lin R. P.
Published: February 2008

Electrons of solar origin in the energy range 2 to 20 keV frequently appear near Earth in impulsive bursts of one to several hours duration. The angular distributions of these particles vary greatly from one event to the next. We discuss four such events. In one of these, the pitch angles are strongly peaked in the forward direction, showing that they have propagated under nearly adiabatic conditions over distances on the order of an astronomical unit. During this event the interplanetary medium was characterized by a low intensity of magnetic fluctuations. At other times the electron events have broad pitch angle distributions. At such times, structures are present in the interplanetary magnetic field which contain magnetic fluctuations in the 3 to 30 Hz range, markedly higher in intensity than in the quiet time interplanetary magnetic field. The pitch angle distributions also possess features that can be understood as adiabatic mirroring effects taking place downstream from Earth. Downstream fields stronger than those near Earth are provided by the convecting interplanetary structures which, typically, have double the quiet time field strength. The observed features of the angular distributions can be understood as a superposition of adiabatic mirroring and pitch angle scattering in the convecting interplanetary magnetic field structures.
Lithospheric age dependence of Off‐Ridge Volcano production in the North Pacific
Authors: Batiza Rodey
Published: February 2008

Data for numbers of seamounts on North Pacific Ocean crust of different age indicate that the production rate of new off‐ridge seamounts (volcanoes) is proportional to the inverse of the square root of the age of the lithosphere. This observation is consistent with several hypotheses which have been offered to explain the origin of off‐ridge oceanic volcanism and, in combination with petrologic and paleomagnetic evidence for small oceanic volcanoes, leads to a new self‐consistent model for off‐ridge volcanism. In this model, the production rate of off‐ridge volcanoes is controlled primarily by the availability of fracture‐zone conduit systems in the thickening lithosphere. In contrast, mantle plume or "hotspot" volcanoes may punch through the oceanic lithosphere. Decreasing production rate of off‐ridge volcanoes on old oceanic lithosphere may be associated with decreasing extent of partial melting of chemically and isotopically heterogeneous mantle material.
Solar wind control of auroral zone geomagnetic activity
Authors: Clauer C. Robert , McPherron Robert L. , Searls Craig , Kivelson Margaret G.
Published: February 2008

An empirical analysis of solar wind‐magnetosphere energy coupling functions is reported. Using the technique of linear prediction filtering with 2.5 minute data, we examine the relationship of auroral zone geomagnetic activity to solar wind power input functions which depend on the solar wind quantities VB², VBs, or V²Bs. In this analysis a least squares prediction filter or impulse response function which relates a solar wind power function to an auroral zone geomagnetic index is designed directly from the data. We find that the computed impulse response functions have the characteristics of a low pass filter with a time delay which may be dependent on the strength of the energy input. While the AL index is reasonably well related to the solar wind energy functions, the AU index shows a substantially poorer relationship. In addition, high frequency variations of the auroral indices and some substorm expansions are not predictable with solar wind information alone, suggesting that internal magnetospheric processes partially control the AL index. We also find that the ϵ parameter which depends on VB² in the solar wind has a poorer relationship to auroral zone geomagnetic activity than a power parameter having a VBs solar wind dependence.
Error in Dasibi flight measurements of atmospheric ozone due to instrument wall‐loss
Authors: Ainsworth J. E. , Hagemeyer J. R. , Reed E. I.
Published: February 2008

Theory suggests that in laminar flow the percent loss of a trace constituent to the walls of a measuring instrument varies as P−2/3, where P is the total gas pressure. Preliminary laboratory ozone wall‐loss measurements confirm this P−2/3 dependence. Accurate assessment of wall‐loss is thus of particular importance for those balloon‐borne instruments utilizing laminar flow at ambient pressure, since the ambient pressure decreases by a factor of 350 during ascent to 40 km. Measurements and extrapolations made for a Dasibi ozone monitor modified for balloon flight indicate that the wall‐loss error at 40 km was between 6 and 30 percent and that the wall‐loss error in the derived total ozone column‐content for the region from the surface to 40 km altitude was between 2 and 10 percent. At 1000 mb, turbulence caused an order of magnitude increase in the Dasibi wall‐loss.
Polar cap electric field dependence on solar wind and magnetotail parameters
Authors: Longenecker D. , Roederer J. G.
Published: February 2008

A magnetic field model with a linearly superposed uniform external field is used to study the effects of the magnetotail field intensity BT on the relationship between the convection pattern in the polar cap and the interplanetary magnetic field (IMF). It is found that as BT increases, the polar cap size increases, the overall electric field intensity decreases, and the dependence of the total "open" flux on the magnitude and direction of the IMF weakens. In addition, the tail field introduces significant differences between the convection patterns corresponding to "toward" and "away" IMF sectors, respectively: in the northern (southern) polar cap, features such as polar cap boundary displacements and electric field intensity gradients are more pronounced when the earth is in an "away" ("toward") sector. On the other hand, in the case of a northward‐tilted IMF, sunward convection in the north (south) polar cap is extended over a larger area for a "toward" ("away") sector. Since dipole tilt was not taken into account in the model, these results should mainly apply to periods around equinox.
Photometric and interferometric observations of the Sar arc event of March 5/6, 1981
Authors: Watanabe T. , Kim J. S.
Published: February 2008

An extraordinary stable auroral red (SAR) arc was observed on the night of March 5/6, 1981 (EST) at a field station near Albany (42.63° N; 73.98°W), New York with a multicolor meridian scanning photometer and a 15‐cm high‐resolution Fabry‐Perot interferometer. The arc was extraordinary in the sense that: (a) it was the most intense arc (∼2.2 kR) observed during the past twelve years at Albany, New York; (b) it was a multiple arc consisting of two SAR arcs (the major arc occurred between zenith angles of 40° (L = 2.7) and 54°S (L = 2.5) throughout the observation period, and the minor arc occurred in close proximity for a duration of only one hour; (c) a visible aurora was not sighted from Albany during the observation period.

Thermospheric temperatures were derived from Doppler line profiles of the [OI] 6300Å emission, obtained within the arc and outside the arc at zenith angles of 70°S, 50°N, and 70°N.

The temperatures within the arc were quite stable with respect to time, even during the period of very rapid and large decrease in the arc intensity, and they were approximately equal to those measured at 70°N. The temperatures at 70°S, which varied considerably in time, were different from those at 50°N or 70°N. The temperatures within the arc were generally higher than those at 50°N or 70°S. The observed enhancement of the temperatures within the arc is much greater than the value predicted by the two‐dimensional model calculations of the SAR arc.
Ionospheric ions in the near Earth geomagnetic tail plasma lobes
Authors: Orsini S. , Candidi M. , Balsiger H. , Ghielmetti A.
Published: February 2008

By comparing data from the plasma experiment on ISEE‐2 and from the ion composition experiment on ISEE‐1, composition and plasma properties of tailward flowing ions in the magnetotail lobes are assessed, in the 50 eV/Z to 11 keV/Z energy range. This population consists mainly of singly charged oxygen ions, with H+ ions contributing in general less than 10%, flowing roughly along magnetic field lines. Hence, it is concluded that these ions are of mainly ionospheric origin. They are detected only during magnetically disturbed periods. Estimates of the Ez electric field componets in the lobes are given.
The Ivrea Zone as a model for the distribution of magnetization in the continental crust
Authors: Wasilewski Peter , Fountain David M.
Published: February 2008

Magnetic properties of the principal lithologies of the Ivrea Zone of northern Italy have been measured. Maficultramafic granulite facies rocks and amphibolites from the granulite‐amphibolite facies transition zone are highly magnetic with susceptibilities greater than 0.5 × 10−3 (cgs) saturation magnetization values greater than ∽ 90 × 10−3 emu/cm³ and Curie points between 570° and 580°C. The magnetic phase is magnetite. All other lithologies are moderately to weakly magnetic. The magnetic mafic granulites are thick and laterally continuous and, thus, would make an appropriate deep crustal source for long wavelength magnetic anomalies in regions typified by low to average geothermal gradients.
Dichlorodifluoromethane, CCl2F2, in the Earth's atmosphere
Authors: Rowland F. S. , Tyler S. C. , Montague D. C. , Makide Y.
Published: February 2008

Atmospheric observations of CCl2F2 concentrations from 1976‐1980 (Rasmussen et al., 1981) have been compared with atmospheric models containing stratospheric destruction alone, and with various added hypothetical tropospheric sinks ranging from 10‐100 year lifetimes. Comparisons are made using (a) absolute atmospheric burdens of CCl2F2; (b) the time trend of relative concentrations; and (c) the ratio of concentrations measured in the northern and southern hemispheres. The atmospheric emissions of CCl2F2 estimated by the Chemical Manufacturers Association (CMA) fail to fit the observations with stratospheric loss alone in all three tests. The inclusion of tropospheric loss processes appreciably worsens the agreement. Three other hypothetical emissions estimates are given which satisfactorily simulate the atmospheric observations by all three tests. The emissions in these models maximize in 1978 or later at more than 500 kilotons/year, in contrast to the CMA maximum of 420 kilotons during 1974. The total emissions of CCl2F2 during 1976 through 1979 in these other models are about 35% greater than in the CMA estimates.
Energetic oxygen precipitation as a source of vibrationally excited N2+ in emissions observed at low latitudes
Authors: Tinsley B. A. , Rohrbaugh R. P. , Sahai Y. , Teixeira N. R.
Published: February 2008

Observations have been made at Mt. Haleakala, Hawaii (dip lat.∼22°N) and Cachoeira Paulista, Brasil (dip lat.∼12°S) of emissions excited by particle precipitation during periods of magnetic activity. The first negative bands of N2+ were found to have a high degree of vibrational excitation at both sites, and with the absence of emissions attributable to hydrogen and helium, this finding leads to the interpretation that the excitation was due to a flux of precipitating oxygen atoms or ions, more plausibly the former, produced by charge exchange of ring current O+ ions with exospheric neutral constituents. More laboratory work is needed to properly interpret the data, but crude estimates of the associated energy deposition and ionization production fall in the range 10−1 to 10+1mWm−2, and 100‐10² cm−3s−1 respectively.
Optical signatures of some magnetospheric processes on the dayside
Authors: Sivjee G. G. , Romick G. J. , Deehr C. S.
Published: February 2008

Ground‐based daytime photometric observations of auroral optical emissions from the cusp region over Longyearbyen (Λ = 75°N) Svalbard are used to illustrate spatial variations in the average energy of particles precipitating in this region. Absolute intensity measurements of daytime auroral OI [¹D → ³P] 6300A emission (indicative of low energy precipitating particles), along the Longyearbyen magnetic meridian generally show a broad (Λ ≈ 2.5° ± 1°) emission region centered, on the average, around Λ = 77° ± 1° N. A relatively confined emission region of higher [OI] 6300A intensity occurrs equatorward of and separated from the cusp; this region is normally associated with visually prominent, structured auroras. Observations of the auroral OII [²D → ²P] 7320A emission, indicative of higher energy precipitating particles, shows that it is weaker in the cusp compared to its intensity in the region of structured auroras. Enhancement of the [OII] 7320A emission maximizes near the equatorward edge of the cusp when compared to the position and extent of the broad [OI] 6300A emission region. These observations indicate higher energy electron precipitation at the equatorward edge of the cusp which might be expected from energization of magnetosheath particles by wave‐particle interactions at the magnetopause.
Double layer formation during current sheet disruptions in a reconnection experiment
Authors: Stenzel R. L. , Gekelman W. , Wild N.
Published: February 2008

When the current density in the center of a neutral sheet is increased to a critical value spontaneous current disruptions are observed. The release of stored magnetic field energy results in a large inductive voltage pulse which drops off inside the plasma in the form of a potential double layer. Particles are energized, microinstabilities are generated, the plasma is thinned, and the current flow is redirected. These laboratory observations qualitatively support recent models of magnetic substorms and solar flares.
Long wavelength irregularities in the equatorial electrojet
Authors: Kudeki Erhan , Farley Donald T. , Fejer Bela G.
Published: February 2008

We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In‐situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion‐acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves.
In‐situ measurements of wave electric fields in the equatorial electrojet
Authors: Pfaff R. F. , Kelley M. C. , Fejer B. G. , Maynard N. C. , Baker K. D.
Published: February 2008

Electric field wave measurements have been performed on two sounding rockets in the equatorial ionosphere. During a daytime flight from Chilca, Peru, intense electrostatic waves were detected on the upward directed electron density gradient. During a nighttime flight from Kwajalein Atoll, similar waves were detected on a downward directed gradient. These results are in agreement with a gradient drift instability explanation of the generation of the waves. The wave amplitudes were as high as 5 mV/m implying perturbation drifts comparable to the driving drift velocities. Power spectra from the turbulent region show a peak at long wavelengths, followed by a nearly flat spectral region before breaking into a power law form with negative index of 3.6–3.7 for λ≤30m. Similarities between the spectra of the two flights suggest that the fundamental processes of the instabilities are the same in the day and nighttime conditions. The rocket data are consistent with radar results presented in a companion paper which show coherent, kilometer scale waves present in the electrojet.
Mars: Gravity data analysis of the Crater Antoniadi
Authors: Sjogren W. L. , Ritke S. J.
Published: February 2008

Topography and gravity information for this 370‐km crater are analyzed to determine a depth of compensation using an Airy isostatic model. A least squares fit to the gravity profile produces an estimate of 115 km for the depth of compensation.
Sea‐salt and the acidity of marine rain on the windward Coast of Samoa
Authors: Pszenny Alexander A. P. , MacIntyre Ferren , Duce Robert A.
Published: February 2008

Preliminary interpretation of pH and sodium concentration data for marine rains collected during February and July, 1981 at American Samoa (14°15′S, 170°34′W) as part of the Sea/Air Exchange (SEAREX) Program indicate that rain is usually slightly more acidic than would be expected on the basis of atmospheric CO2‐pure water equilibrium, in this remote region of the tropical South Pacific Ocean. The data are consistent with calculations of pH using the alkalinity equation for "model" solutions containing only sea‐salt and traces of strong acids in equilibrium with atmospheric CO2. Alkalinity due to sea‐salt appears to affect pH significantly only when the salinity of the rain is greater than 0.01 ‰ or 3000 µg Na/kg. The observed range of pH values is much smaller than has been observed recently at subtropical marine sites: this, along with the relatively high average pH value, suggests that climatic factors influence levels of acidity in rain over remote ocean areas.
In‐situ generated gravity waves as a possible seeding mechanism for equatorial spread‐F
Authors: Anderson D. N. , Richmond A. D. , Balsley B. B. , Roble R. G. , Biondi M. A. , Sipler D. P.
Published: February 2008

Recent observations have shown that, prior to the onset of equatorial spread‐F, there exists an altitude modulation in bottomside F‐region electron density contours. It has generally been accepted that such a modulation is caused by internal‐gravity waves propagating upward from below. In this brief note we suggest that gravity waves may be generated in situ, via the wind shear mechanism. Theoretical calculations and some observations indicate that large wind shears can occur during early evening hours in the low latitude thermosphere. We show that the wind shear may possibly generate gravity waves with horizontal wavelengths on the order of a few hundred kilometers, which is the scale of the observed electron density modulation.
On the horizontal distribution of the equatorial thermospheric midnight temperature maximum and its seasonal variation
Authors: Herrero F. A. , Spencer N. W.
Published: February 2008

The temperature measurements taken with the NATE experiment on the Atmosphere Explorer‐E satellite during 1977 and 1978 are used to obtain the horizontal two‐dimensional distribution of the thermospheric nighttime temperature maximum between latitudes 19.8 deg. south and 19.8 deg. north in the altitude range from 250 to about 370 km. Since the satellite orbital period is short in comparison with the Earth’s rotation, the local time variations observed are equivalent to longitude variations. Thus, the measurements may be used to study the horizontal distribution of the temperature in latitude and longitude. The data are used to generate temperature maps for the four seasons. The maps show that the nighttime temperature maximum often occurs first at the geographic equator, and shows a tendency to be largest there. A seasonal rotation of the distribution of the maximum is observed in which the maximum occurs in the summer hemisphere before it occurs in winter. The summer maximum is significantly larger than the winter maximum. The local time of occurrence of the maximum in either hemisphere shows an annual oscillation about local midnight with an amplitude of about 3 hours. The observations indicate that the nighttime temperature oscillates with higher frequencies and amplitudes in the summer hemisphere, thus suggesting that the semidiurnal and higher order tidal modes are stronger in that hemisphere.