bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatiles in the Martian regolith
Authors: Clark Benton C. , Baird A. K.
Published: February 2008

An inventory of released volatiles on Mars has been derived based upon Viking measurements of atmospheric and surface chemical compositionand upon the inferred mineralogy of a ubiquitous regolithassumed to average 200m in depth. This model is consistent with the relative abundances of volatiles (except for S) on the Earth's surfacebut implies one‐fifteenth of the volatile release of Earth if starting materials were comparable. All constituents are accommodated as chemical components ofor absorbed phases onregolith materials — without the necessity of invoking unobservable deposits of carbonatesnitratesor permafrost ice.
Geodetic measurements of rifting associated with a seismo‐volcanic crisis in afar
Authors: Ruegg J. C. , Lépine J. C. , Tarantola A. , Kasser M.
Published: February 2008

The resurvey of both a geodetic network and a levelling linesoon after a seismotectonic crisis which occured inside the subaerial rift of Asal‐Ghoubbet in Afarshows an horizontal extension of about 2 m and a vertical movement up to 70 cm. These movements showed clearly the mechanism of rifting in a setting similar to a typical oceanic rift valley. The observed data are well explained by a brittle elastic model and a rebound mechanism.
Evidence for sea breezes on the Alaskan Beaufort Sea Coast
Authors: Kozo Thomas L.
Published: February 2008

Atmospheric environmental data collected in August 1976 and 1977 along the Beaufort Sea coast of Alaska exhibited both circumstantial and direct evidence of the existence of sea breezes at 70°N latitude. To estimate the total atmospheric boundary layer turninga two‐dimensional least squares technique was used to derive the three hourly gradient wind (above the atmospheric boundary layer) with data from surface pressure stations for simultaneous comparison to surface wind data. Results indicated the average turning of the wind from above the boundary layer to the surface was 120° on sea breeze days. Rotary spectra from time series data of surface winds measured at offshore and onshore sites have shown the horizontal extent of the sea breeze influence to include at least a 37 km zone centered on the coastline.

The sea breeze is largely responsible for the increased persistence of surface onshore (northeasterly and easterly) winds documented in August historical data for the Alaskan Beaufort Sea coast.
Solar activity and total atmospheric ozone
Authors: London Julius , Reber Carl A.
Published: February 2008

Analyses are presented of the association between two parameters of solar activity (Lyman‐α and 10.7 cm flux) and global total ozone as determined from Nimbus observations for the period April‐December 1970 (IRIS observations)and April 1970 ‐ April 1972 (BUV observations); and between Lyman‐α and global total ozone as observed at ground stations and the ozone concentration in the lower and middle stratosphere in the subtropics for the period 1969‐1972. It is shown that the high correlations discussed in other published studies between these solar parameters and nine months of IRIS data resulted from the use of a very limitedseasonally unfiltered data set.
Pyroxenes from planetary basalts: Characterization of "other" than quadrilateral components
Authors: Papike J. J. , White C.
Published: February 2008

As part of a NASA sponsored program entitled "Basaltic Volcanism on the Terrestrial Planets" we have been involved in the synthesis of the silicate mineralogy of a planetary suite which includes Archean, Columbia Plateau, deep sea, basaltic meteorites, Hawaiian, island arc, Keweenawan, lunar highlands, lunar mare and Rio Grande basalts. We treated 1263 pyroxene microprobe analyses in our statistical and graphical analysis. The most important "Others" substitutional couple for all of the planetary suites combined is VITi4+‐IVAl23+. It enters pyroxenes mainly as the component CaTiAl2O6. A very important component in pyroxenes from terrestrial basalts is CaFe3+SiAlO6. This emphasizes the importance of fO2 in pyroxene‐liquid elemental partitioning. At the relative high oxygen fugacities of terrestrial petrogenesis, iron enters the pyroxene structure both as Fe3+ and Fe2+ whereas in lunar and most basaltic meteorite pyroxenes, iron is Fe2+ only. Inspection of this large number of high quality pyroxene analyses demonstrates that these phases carry a signature of the planetary body in which they evolved.
Energetic (∼ 100‐keV) tailward‐directed ion beam outside the Jovian plasma boundary
Authors: Krimigis S. M. , Armstrong T. P. , Axford W. I. , Bostrom C. O. , Fan C. Y. , Gloeckler G. , Lanzerotti L. J. , Hamilton D. C. , Zwickl R. D.
Published: February 2008

The hot plasma instrument on the Voyager‐2 spacecraft measured a nearly monoenergetic (∼ 100 keV) ion beam several hours after crossing the Jovian plasma boundary on the nightside of the planet. The beam, deduced to consist primarily of heavy ions, persisted for about four hours and originated from the general direction of Jupiter. The energy density of the beam was ∼ several times the energy density of the magnetic field (β > 1). This beam, a product of an as yet not understood Jovian plasma acceleration mechanism, provides a dramatic example of the energetic dynamics of Jupiter’s magnetosphere.
Temperature dependence of the rate coefficient for charge exchange of metastable O+(²D) with N2
Authors: Torr M. R. , Torr D. G.
Published: February 2008

Using a database of aeronomical parameters measured by the Atmosphere Explorer‐C satellite, we deduce a temperature dependence of the reaction rate coefficient for the charge exchange of O+(²D) with N2,

The results indicate that the Atmosphere Explorer values determined over the temperature range ∼700 to 1900°K, are not in conflict with the laboratory measurements made at higher temperatures. From these results, we show that the rate coefficient can be represented by and The shape of the temperature variation is found to be similar to that for the ion atom interchange rate coefficient of ground state oxygen ions with N2.
Pulsating aurorae: Evidence for flux limiting
Authors: Davidson G. T. , Sears R. D.
Published: February 2008

Theoretical models based upon the concept of self‐modulated VLF wave‐electron interactions have been proposed to explain pulsating aurorae. These models incorporate the idea of a trapping limit, above which strong diffusion into the loss cone rapidly removes any excess electrons. At flux values near the trapping limit, perturbations of the trapped electron distribution can result in cyclic wave growth and electron precipitation. The trapping limit is thus related to the energy deposited and the characteristic energy of electrons precipitated in pulsating aurorae. Photometric measurements of the total energy deposit and of the mean energy parameter made at Chatanika, Alaska (invariant geomagnetic latitude, 65°) indicate that the well‐developed pulsations are caused mainly by a modulation of the mean energy parameter. Thus, a nearly constant "limiting" value for the precipitating flux is measured
from which a trapped flux limit of J ≅ 3 × 109 el/cm² sec can be inferred.
On Saturnian cosmic ray cutoff rigidities
Authors: Sauer Herbert H.
Published: February 2008

The theory of charged particle motion in a dipole field has been well developed, however because of the importance to the geomagnetic field of contributions other than dipolar, interest in the subject has remained primarily pedagogical over the past decade. Recent measurements by Ness et al. and Smith et al. have shown that the magnetic field of Saturn is essentially dipolar, with the axis of the dipole approximately aligned with the planetary rotation axis. This note briefly sketches the dipole geomagnetic cutoff theory and demonstrates the scaling required for its applicability to energetic particle measurements in the vicinity of Saturn.
Large scale 6300Å, 5577Å, 3914Å dayside auroral morphology
Authors: Murphree J. S. , Cogger L. L. , Anger C. D. , Ismail S. , Shepherd G. G.
Published: February 2008

Simultaneous observations at 6300Å, 5577Å, and 3914Å by the ISIS‐2 satellite are used to examine the morphology of auroras in the noon sector. While a minimum in intensity is generally observed in the 5577Å and 3914Å emissions from approximately 10 to 12 MLT, the 6300Å emissions may be most intense there. The latitudinal extent of 6300Å emissions is much greater than that of 5577Å and 3914Å and discrete features are generally not apparent in the 6300Å emission. Peak levels of 6300Å emission may occur at noon, prenoon, or afternoon and thus 6300Å emission is not confined to the "gap" or minimum in the day side discrete aurora seen at 5577Å and 3914Å. Substantial 6300Å emission occurs on closed field lines which is evidently due to boundary layer plasma. No optical signature of direct entry particles is identified.

It is apparent that large differences in morphology and intensity exist between wavelengths in dayside auroras due to different source regions for the precipitating particles. For example, Cogger et al. (1977) have pointed out that the gap in dayside emissions (observed at 5577Å) is really a wavelength dependent feature in that 6300Å measurements indicate a maximum at noon rather than a gap (Shepherd and Thirkettle, 1973; Shepherd et al., 1976). Whalen and Pike (1973) have also shown that an enhanced band of 6300Å emission occurs across the dayside and when discrete midday auroras occur they locate within this band. Heikkila et al. (1972) have used 4278Å and 6300Å data from aircraft flights and satellite particle measurements to characterize the nature of the particle precipitation and the resulting aurora on the dayside. However, with ground based or direct satellite observations only a single meridian can be observed in a short period of time.

In this paper, the "instantaneous" relationship between 6300Å, 5577Å and 3914Å emissions in the entire noon sector is studied to provide new information of the two dimensional morphology of these emissions. The data were taken by the Auroral Scanning Photometer (ASP) and the Red Line Photometer (RLP) on ISIS‐2 during the northern hemisphere winter solstice period in December 1974.
On magnetic curl in front of the magnetosphere boundary
Authors: Podgorny I. M. , Dubinin E. M. , Potanin Yu.N.
Published: February 2008

The structure of the magnetic field at the boundary of the artificial magnetosphere was studied with the southern component of the magnetic field in the plasma flow. It is shown that due to reconnection of the fields in the region of polar clefts the extended magnetic curl occurs that is disintegrated into smaller loops, magnetic islands. The comparison of the laboratory experimental results and the ISEE results of the magnetic measurements is given.
Explosion seismic sounding of throws and dips in the continental Moho
Authors: Hirn A. , Daignières M. , Gallart J. , Vadell M.
Published: February 2008

Using critical‐distance Moho reflections on fan‐profiles, sections of the topography of the crust‐mantle boundary across the Pyrenean mountain range are obtained. At two different places throws of more than 10km in the Moho are detected, they are situated beneath the same surface fault. Together with other features such as local dips, these results have a strong bearing on models of regional evolution. The existence of fractures through the continental lithosphere is documented by that simple technique using the Moho as a marker.
Mountain barrier baroclinity effects on surface winds along the Alaskan Arctic Coast
Authors: Kozo Thomas L.
Published: February 2008

The deployment of offshore pressure and position relaying buoys in February 1979 within the arctic ice pack has allowed for a more complete investigation of a wintertime mesoscale meteorological effect known as mountain barrier baroclinity (MBB). Total atmospheric boundary layer turning with height was estimated by comparing computed three hourly geostrophic winds (above the boundary layer) to simultaneous surface winds at Barter Island, Alaska. This total turning compared closely with wind velocity versus height data obtained through rawinsonde launches at Barter Island. Results indicate that the average turning of the wind from above the boundary layer to the surface was 140° during periods of MBB influence. In addition the average difference between simultaneously measured surface winds at Barter Island and Pt. Barrow, Alaska (during MBB periods) was 140°, which cannot be explained by existing synoptic (large‐scale) weather charts.

The evidence explains the wintertime abundance of west to southwest winds seen on historical monthly wind direction histograms from Barter Island (64 km north of the Brooks Range) while Pt. Barrow (300 km north of the Brooks Range) histograms for similar months show an east to northeast bias. Finally, the occurrences of the MBB effect and a summertime sea breeze effect have been related to arctic tundra surface albedo.
Narrow‐band Jovian kilometric radiation: A new radio component
Authors: Kaiser M. L. , Desch M. D.
Published: February 2008

We describe a new component of Jupiter's radio spectrum. This component emits in a very narrow bandwidth (≤ 40 kHz) near 100 kHz. Its waveform is a very smooth and gradual rise and subsequent fall in intensity over typically two hours. The emission is polarized with left‐hand polarization associated with the Jovian northern magnetic hemisphere and righthand with the south. The most interesting feature of the emission is its deviation from a strict System III rotation period repetition rate. The emission source of this narrow‐band component clearly rotates slower by 3‐5% than all other forms of Jovian radio emission. Propagation considerations coupled with this observed lack of corotation point to a source region near the magnetic equatorial plane at the outer ‘edge’ (8‐9 RJ) of the Io plasma torus.
Destruction of N(²D) by O2: A major source of 6300 Å dayglow emission
Authors: Torr D. G. , Richards P. G. , Torr M. R.
Published: February 2008

Using the results of a recent study of the sources of O(¹D) atoms in the aurora we show that the reaction constitutes the main source of 6300 Å surface brightness above 150 km altitude in the daytime thermosphere. In summer the volume emission rate of this source is 2.5 times larger than the sum of all other sources at 180 km, and ∼ 1.5 times as large in winter. Inclusion of the new source alleviates the need for the large dissociation frequency of O2 by solar UV radiation in the Schumann‐Runge wavelength range found in previous work (JO2 = 3 × 10−6 s−1), thus bringing the 6300 Å airglow measurement into harmony with the measurements of the Schumann‐Runge continuum made on the Atmosphere Explorer (AE) satellites; i.e., JO2 = 1.5×10−6 s−1. Neglect of the N(²D) source of O(¹D) in the past has resulted in an overestimation of O2 concentrations in the twilight thermosphere from both ground based and satellite measurements of the 6300 Å emission. When the N(²D) source of O(¹D) is taken into account the rate coefficient for quenching of O(¹D) by N2 is estimated to be ∼ 30% higher than that determined in a recent AE study; i.e., the new value is 4 ± 1 × 10−11 cm³ s−1.
Heat flow through the floor of the Scotia, far South Atlantic and Weddell Seas
Authors: Zlotnicki V. , Sclater J. G. , Norton I. O. , Von Herzen R. P.
Published: February 2008

We discuss the first heat flow measurements taken in the Atlantic section of the Antarctic Ocean. The one value from the Scotia Sea is compatible with the youthful age proposed for this sea. The values around the America‐Antarctica ridge are low and scattered as expected from regions of rough topography and variable sediment cover. The values from the well sedimented western Weddell Sea are surprisingly high for a deep, isostatically adjusted sedimentary basin, and decrease to the Southeast. Such high heat flow could result from a marginal basin type origin or be related to a large difference in age across the Sea.
Observations of the ring current composition at L < 4
Authors: Lundin R. , Lyons L. R. , Pissarenko N.
Published: February 2008

Observations showing that the low energy (≲ 17 keV) portion of the ring current at L ≲ 4 is composed mainly of O+ and He+ ions during quiet times and the recovery of magnetic storms are presented. The data were obtained from the ion composition experiment on board the PROG‐NOZ‐7 satellite during several passes through the ring current region. For L ≲ 3.5, the relative abundance of H+ was only a few percent of the ion energy density in the energy range of 0.2‐17 keV. Although O+ normally dominates for L ≲ 4, the relative contribution of He+ increases with decreasing L, and in one case became more abundant than O+ for L ≲ 3. One example of a storm injection shows dominance by O+ ions (∼ 82%) with H+ only giving a minor contribution (∼ 15%) to the density. These observations are consistent with inferences based on charge exchange, H+ being most rapidly lost and He+ being the most stable.
The isotopic composition of argon included in an Arkansas diamond and its significance
Authors: Melton Charles E. , Giardini A. A.
Published: February 2008

The isotopic composition of argon entrapped in a 6.3 carat, Type I, Arkansas, U. S. A. diamond (emplacement date 106 ± 3 m.y. ago) has been determined by mass spectrometric techniques. This was done by crushing the stone in a diamond crusher attached to the high vacuum inlet system of a high‐sensitivity research mass spectrometer. The results show an 40Ar/36Ar value of 189 compared to a ratio of 294 for atmospheric argon, and an 38Ar/36Ar value of 0.18 almost identical to that for atmospheric argon (0.19). The isotopic data have been applied to a model of the outer Earth to test the crystallization age of the diamond. The results may be interpreted in terms of diamond crystallization about 3.1 billion years ago.

The existence of primordial 36Ar and 38Ar (non‐radiogenic isotopes) shows that the Earth had not completely degassed at the time of diamond crystallization. In fact, if the diamond is assumed to be a representative sample of the upper mantle with respect to fluid content, the mass of primordial 36Ar in this region of the Earth is calculated to be 1 × 1010 tons at the time of diamond crystallization, or 2.5 × 10−5 ppm by weight.
Surface reflections of Pioneer Venus Probe radio signals
Authors: Croft Thomas A.
Published: February 2008

As the four Pioneer Venus probes fell within the atmosphere toward the surface of Venus, each of them transmitted a radio signal directly to Earth. Because of the relatively broad antenna beam‐width of these small probes, some of the transmitted power went down to the surface of Venus. I report here the discovery that the radio signals scattered off the surface are not only detectable but that their characteristics can be determined with a surprising degree of certainty. From these characteristics one can determine parameters of the Venusian atmospheric winds and of the surface that promise to be useful. Most of the scattered energy is that which originally radiated from the probes in a near‐horizontal direction; the downward‐directed radiation is detectable but much weaker. Refraction in the atmosphere of Venus clearly plays a significant role in establishing both the strength of scatter and its Doppler shift. For this first report, I stress the aspects of analysis that bear on the identification of these weak echoes.
Coincident radar and rocket observations of equatorial spread‐F
Authors: Szuszczewicz E. P. , Tsunoda R. T. , Narcisi R. , Holmes J. C.
Published: February 2008

Coordinated measurements of equatorial spread‐F conducted during July 1979 at the Kwajalein Atoll have yielded the first definitive space‐ and time coincident radar and rocket observations of small scale irregularities and large scale plasma depletions. The results have shown that:

(a) During conditions of well‐developed equatorial spread‐F the most intense "in situ" irregularities occurred on the bottomside F‐layer gradient.

(b) Within a large scale topside F‐layer depletion radar backscatter and "in situ" irregularity strengths maximized near the depletion’s upper wall.

(c) Ion composition within a topside depletion provided signatures of its bottomside source domain and estimates of average maximum vertical drift velocity. For long‐lived depletions, it was found that molecular‐ion signatures (NO+ and O2+) can be lost while bottomside levels of N+ can be maintained when [O+] ≈ Ne ≫ [NO+] + [O2+]; and finally,

(d) Large scale fluctuations of O+ accompanied by a near‐constant level of NO+ and O2+on the bottomside F‐layer gradient suggests that neutral atmospheric turbulence is not a major source for bottomside ionospheric plasma irregularities and the associated triggering of equatorial spread‐F.
Rocket observations of the vertical distribution of ozone in the polar night and during a mid‐winter stratospheric warming
Authors: Hilsenrath Ernest
Published: February 2008

Rocket ozone soundings have been conducted in the stratosphere and lower mesosphere at high latitudes during winter. The collection of soundings show a high degree of variability when compared to ozone distributions measured during summer and at lower latitudes. The concurrently observed temperature and winds also show large variations which can be qualitatively related to the ozone profiles. Two most unusual ozone profiles were observed in January 1979 over Alaska during a stratospheric warming event. Both ozone profiles were consistent in showing the measured mixing ratios to be higher at 50 km than those measured at 40 km, a feature never reported before. This feature is related to the concurrently observed wind and temperature distributions and the NMC analyses of pressure height fields. The polar night ozone observations in the upper stratosphere and lower mesosphere suggest some temperature dependence, but transports seem to play an important role.
Magnetic islands in the quiet magnetotail
Authors: Zwingmann Wolfgang , Schindler Karl
Published: February 2008

Equilibrium configurations of the quiet geomagnetic tail are computed numerically, relaxing the condition of smooth variation along the tail axis. The results strongly suggest that the quiet plasma sheet will generally include magnetic islands, which substantiates recent observations of Lui and Meng (1979) on theoretical grounds. These islands constitute an equilibrium phenomenon and they are not directly related to dynamic processes such as the tearing instability. Their presence therefore does not impose any constraint on the role of tearing for geomagnetic activity.
Observations of large scale steady magnetic fields in the dayside Venus ionosphere
Authors: Luhmann J. G. , Elphic R. C. , Russell C. T. , Mihalov J. D. , Wolfe J. H.
Published: February 2008

Although the dayside ionosphere of Venus is often “field‐free” except for fine scale features, large scale, steady ionospheric magnetic fields with magnitudes sometimes exceeding 100 gammas are occasionally observed by the Pioneer Venus Orbiter magnetometer. These fields are mainly horizontal and can assume any angle in the horizontal plane. The orientation of the field may change along the spacecraft trajectory. The field magnitude in the upper ionosphere usually shows a distinct minimum near ∼200 km altitude, but the altitude profile is otherwise arbitrary. With few exceptions, the observations of these large scale fields occur when periapsis is at solar zenith angles <50°. The occurrence of large scale fields is often coincident with the observation of high solar wind dynamic pressures by the Pioneer Venus Orbiter plasma analyzer closely following the ionosphere encounter. However, the detection of this phenomenon even during some orbits for which the dynamic pressure is not extraordinarily high suggests that other factors, such as hysteresis effects, must also play a role in determining the occurrence frequency of large scale magnetic fields in the dayside Venus ionosphere.
First measurements of total chlorine and bromine in the lower stratosphere
Authors: Berg W. W. , Crutzen P. J. , Grahek F. E. , Gitlin S. N. , Sedlacek W. A.
Published: February 2008

A total halogen collection system employing ultra‐pure activated charcoal traps has been developed for use in the stratosphere aboard aircraft and balloon sampling platforms. Neutron activation techniques for low‐level chlorine, bromine, and iodine analysis within the activated charcoal sampling matrix were developed. Initial results from six aircraft flights and one balloon mission in the lower stratosphere are presented for latitudes ranging from 16°N to 67°N. Little variability was observed in twelve total, gaseous and particulate chlorine (Cltot) determinations as a function of latitude at 20 km with values ranging between 2.7 ± .9 ppbv and 3.2 ± .7 ppbv. Five total bromine (Brtot) values showed substantial variability ranging from 7 ± 4 pptv to 40 ± 11 pptv. No iodine was observed in any samples but a calculated Itot upper limit of < 3 pptv was determined.
Measurements of stratospheric sulfate mixing ratio with a multi filter sampler
Authors: Gandrud B. W. , Lazrus A. L.
Published: February 2008

A new multi filter sampler (MFS) was used to measure daily profiles of sulfate aerosol in Alaska during the period July 16 through July 19, 1979. During these 4 days, the variability is such that the percent standard deviation of an individual profile from the mean is as high as 23%. The results of these flights are compared with the Project Airstream results from the same time period.
An experimental assessment of the O3/H2O interference problem in the detection of natural levels of OH via laser induced fluorescence
Authors: Davis D. D. , Rodgers M. O. , Fischer S. D. , Asai K.
Published: February 2008

Using simulated tropospheric conditions in a laboratory study as well as OH field measurement data from project GAMETAG (Global Atmospheric Measurements Experiment on Tropospheric Aerosol and Gases), an experimental assessment has been completed of the O3/H2O/OH laser induced interference problem. These results indicate that, for the tropical marine boundary layer, the OH interference level averaged ∼38% during the GAMETAG field measurements program. The average “useable” UV laser energy employed in these boundary layer OH measurements was 165 µJ. OH interference estimates in the case of the free troposhere were substantially lower, being ∼13% for an average “useable” UV laser energy of 250 µJ. Modelling calculations suggest that the existing O3/H2O/OH interference problem could be reduced still further, by factors of five to six, through the use of very narrow UV laser pulses (i.e., .5 to 1 ns vs. 7 ns).
Iue high‐resolution observation of the Venus dayglow spectrum 1280‐1380 Å
Authors: Durrance Samuel T. , Conway Robert R. , Barth Charles A. , Lane A. L.
Published: February 2008

The spectrum of the Venus dayglow between 1280 and 1380 A has been measured in high‐resolution with the International Ultraviolet Explorer. Seven exposures which were made with the short wavelength camera in the high‐dispersion mode using the large aperture were combined to give a total exposure time of 309 min. The atomic oxygen lines at 1302.2, 1304.9, 1306.0, and 1355.6 A are present. In addition, the (14,3) and (14,4) bands of the carbon monoxide fourth positive system at 1317 and 1354 A respectively are identified. These bands are compared with synthetic spectra, showing the excitation mechanism to be fluorescent scattering of solar Lyman alpha radiation.
Equations of state of CaO under static pressure conditions
Authors: Mammone J. F. , Mao H. K. , Bell P. M.
Published: February 2008

Experimental static high‐pressure data on the volume equation of state of the B1 and B2 phases of CaO in the range 1 bar‐650 kbar agree with existing low‐pressure data and with an equation of state calculated from shock‐wave experiments. The density of the B2 phase is close to that of the lower mantle, so the properties of CaO could be consistent with theories of the earth's formation by inhomogeneous accretion.
Bi‐directional streaming of solar wind electrons >80 eV: ISEE evidence for a closed‐field structure within the driver gas of an interplanetary shock
Authors: Bame S. J. , Asbridge J. R. , Feldman W. C. , Gosling J. T. , Zwickl R. D.
Published: February 2008

In near time coincidence with the arrival of helium enriched plasma driving the shock wave disturbance of November 12‐13, 1978, strong bi‐directional streaming of solar wind electrons >∼80 eV was observed with Los Alamos instrumentation on ISEE 3. The streaming persisted for many hours simultaneously parallel and anti‐parallel to the interplanetary magnetic field which was directed roughly perpendicular to the sun‐satellite line. This example of bi‐directional streaming clearly cannot be explained by field line connection to either the earth's bow shock or the outward propagating interplanetary shock which passed ISEE 3 ∼16 hours earlier. The event is best explained if the local interplanetary field was a part of either a magnetic bottle rooted at the sun or a disconnected loop propagating outward.
Characterization of viscous remanent magnetization in single‐ and multi‐domain magnetite grains
Authors: Tivey Maurice , Johnson H. Paul
Published: February 2008

Viscous remanent magnetization acquisition and decay coefficients are shown to be strongly affected by the previous magnetic history of the samples. Demagnetization of coarse grain, multi‐domain, magnetite samples using alternating magnetic fields causes a sharp reduction in the ability to acquire viscous magnetization. VRM acquisition in single‐domain particles is not affected by AF demagnetization but is sensitive to the amount of time the sample is kept in zero magnetic field storage prior to applying the VRM field. VRM acquisition coefficients are strongly dependent on magnetic grain size with high values at both very small and very large grain diameters.
Polar cap arcs and the plasma sheet
Authors: Meng Ching‐I.
Published: February 2008

This letter suggests that most of the so‐called ‘polar cap arcs’ with the sun‐aligned orientation at the high geomagnetic latitude region occurring during the quiescent magnetosphere are actually a part of discrete arcs in the auroral oval as a consequence of the poleward widening of the quiet auroral oval. This suggestion is based on (1) a detailed examination of two months of DMSP electron precipitation data and simultaneous auroral observations, (2) the observed widening in the latitudinal extent of the auroral oval precipitation to the very high geomagnetic latitude (≳80°) and the simultaneous occurrence of the sun‐aligned arcs, and (3) the conjugate widening of the quiet auroral oval over both the northern and southern polar regions. The new interpretation of the ‘polar cap arcs’ is discussed in terms of the present understanding of the solar wind‐magnetospheric interaction.
Gravity wave activity in vertical winds observed by the Poker Flat MST Radar
Authors: Ecklund W. L. , Gage K. S. , Riddle A. C.
Published: February 2008

Over 30 days of nearly continuous observations of the vertical wind up to 20 km obtained using part of the MST radar at Poker Flat, Alaska, are presented in this report. These observations are typical of a longer 6‐month set of observations and demonstrate several new features. The most obvious feature is the extent to which the magnitude of the vertical wind fluctuations is controlled by propagating planetary scale waves, which modulate the large‐scale wind field. Enhanced wind and wind shear in intense baroclinic zones greatly increase gravity wave activity as seen in the vertical winds. Although shorter period fluctuations in vertical velocity on occasion show very regular sinusoidal oscillations with periods from 5 to 30 minutes, typically the vertical velocity fluctuations are irregular with no well‐defined oscillation period. Steady vertical winds of up to 1 m/s lasting for several hours are observed at certain low altitudes when background winds and wind shear are enhanced. The occurrences are not unusual and are probably due to mountain lee wave activity.
The origin of particulate organic carbon in the marine atmosphere as indicated by its stable carbon isotopic composition
Authors: Chesselet R. , Fontugne M. , Buat‐Ménard P. , Ezat U. , Lambert C. E.
Published: February 2008

Organic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso Sea) during the SEAREX (Sea‐Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2µg.m−3, in agreement with previous literature data. The major mass of POC was found on the smallest particles (r<0.5µm). The 13C/12C of the small particles is close to the one expected (δ13C = 26 ± 2‰) for atmospheric POC of continental origin. For all the samples analysed so far, it appears that more than 80% of atmospheric POC over remote marine areas is of continental origin. This can be explained either by long‐range transport of small sized continental organic aerosols or by the production of POC in the marine atmosphere from a vapor phase organic carbon pool of continental origin. The POC in the large size fraction of marine aerosols (<20% of the total concentration) is likely to have a direct marine origin since its carbon isotopic composition is close to the expected value (δ13C = −21 ± 2‰) for POC associated with sea‐salt droplets transported to the marine atmosphere.
Interferometer studies of equatorial F region irregularities and drifts
Authors: Kudeki E. , Fejer B. G. , Farley D. T. , Ierkic H. M.
Published: February 2008

A radar interferometer technique developed at Jicamarca, Peru and first used to study electrojet irregularities has now been used successfully to study plasma turbulence in the equatorial F region. Our first results have shown that the most ‘turbulent’ echoes appear to come from a region that extends for tens of kilometers in altitude but for only a kilometer or less in the east‐west direction. This slab may very well be the wall of a depleted region, a plasma ‘bubble’. Sometimes the irregularities can be tracked as they move eastward or westward. Velocity profiles for the evening period obtained in this way show a strong shear, with westward velocities at the lowest altitudes observed and eastward velocities above. A plausible explanation for this shear is that the westward drifts are driven by electric fields produced by westward E region winds and mapped up along magnetic field lines, while at higher heights, where the electron density is greater, the drifts are controlled by the F region dynamo driven by eastward winds.
Quenching of O(¹S) by O2(a¹Δg)
Authors: Slanger T. G. , Black G.
Published: February 2008

The assignment of a rate coefficient on the order of 1 × 10−11 cm³ molec−1 s−1 to the reaction O(¹S) + O(³P) → O + O is erroneous. Previous experiments have not taken into account the presence of O2(a¹Δg) in the O(³P) atom streams, and it is demonstrated that O2(a¹Δg) is the O(¹S) quencher in these studies, with a rate coefficient of (1.7 ± 0.3) × 10−10 cm³ molec−1 sec−1. The consequences of such a rapid reaction are discussed in terms of mesospheric and auroral modeling.
The effect of gravity waves on specular echoes observed by the Poker Flat MST Radar
Authors: Gage K. S. , Carter D. A. , Ecklund W. L.
Published: February 2008

This paper presents an analysis of a gravity wave event near the tropopause as seen by the vertically looking antenna of the Poker Flat, Alaska, MST radar. The observations are presented as time series of vertical velocity, signal power and spectral width. These parameters are found to oscillate in a systematic fashion that illustrates the effect of gravity waves on the specular echoes. This is seen most clearly by examining the changing appearance of the Doppler spectrum with the phase of the gravity wave. The principal result is that specular echoes are observed only at certain phases of the wave. Examination of a large sample of data shows that more generally the occurrence of gravity waves tends to destroy specularity. The decrease in the magnitude of specular echoes can be parameterized by the width of their Doppler spectra.
On the radial structure of Saturn's rings
Authors: Ward William R.
Published: February 2008

Radial diffusion in a particulate Keplerian disc under the influence of a viscosity law ν(σ) that decreases with surface density σ more steeply than σ−1 [i.e., d(νσ)/dσ < 0] will promote the breakdown of the system into an ensemble of thin rings. Possible application to Saturn’s rings is considered.
Some size dependent properties of joints and faults
Authors: Barton Nick
Published: February 2008

Marked strength‐size effects are observed when joints are subjected to shear. This is due to the mobilization of larger, but less steeply inclined asperities as sample size is increased. The displacement required to mobilize strength is also increased by the changing size of sample. These observed size effects indicate that large scale tests should be performed to obtain realistic data concerning shear behavior, dilation, and associated permeability changes.
Continental rifting and the origin of Beta Regio, Venus
Authors: McGill George E. , Steenstrup Susan J. , Barton Colleen , Ford Peter G.
Published: February 2008

Topographic maps based on Pioneer Venus altimetry suggest that Beta Regio, an elevated feature centered at 27°N., 282°E., is analogous to domes associated with continental rift systems on Earth. This interpretation is consistent with the commonly quoted analogy between the East African rift system and the topography of the region from Beta Regio southward to Phoebe Regio. If Beta Regio is a dome, major structural uplift of the crust of Venus is implied, suggesting a more dynamic upper mantle than would be the case if Beta Regio were simply a large volcanic construct.
Excitation of the Earth’s polar motion: A reassessment with new data
Authors: Wilson Clark R. , Gabay Steven
Published: February 2008

A comparison of a revised ILS polar motion series for the years 1901 to 1970 with an atmospheric time series shows evidence for coherence near the period of the 14 month Chandler motion. The same ILS series, and two other BIH series, have also been used to compute shifts in the apparent pole position near the times of the 1960 Chilean and 1964 Alaskan earthquakes. These shifts are not convincingly similar to those predicted by other investigators from earthquake source parameters. In addition, there is disagreement among the shifts computed from the various polar motion data sets. Thus, a conclusive determination of the relative roles of atmospheric, earthquake and other sources in the excitation of polar motion will probably require improved observations of both the proposed excitation phenomena and the earth’s polar motion.
A computer model study of the propagation of the long‐range Pn phase
Authors: Gettrust Joseph F. , Frazer L. Neil
Published: February 2008

Synthetic long‐range (high‐frequency) Pn phases that fit both the arrival times and, more importantly, the characteristic long coda duration of this phase are generated using a velocity‐depth model consistent with long‐range refraction and surface wave observations. These synthetics show that a crustal guided‐wave plays an important part in the character of "typical" long‐range Pn coda; in particular, the largest amplitude arrivals at ranges greater than about 8° propagate through the crustal wave guide. Comparison of a synthetic long‐range Pn signal with an observation of this phase at 8° range suggests that any P‐velocity inversion at the base of the lithosphere must be small. This result is consistent with the anomalously high Q values for Sn reported by Walker et al. [1978] since a P‐velocity inversion much smaller than the associated S‐velocity inversion means that tunneling would extract much more low‐frequency energy from long‐range Sn than it would from long‐range Pn.
Seasonal variations in the upper Arctic Ocean as observed at T‐3
Authors: Morison James , Smith J. Dungan
Published: February 2008

Hydrographic data from T‐3 are analyzed to illustrate the behavior of the Arctic mixed layer. The mixed layer depth fluctuates 11 m annually and mixed layer salinity fluctuates 0.32‰. The fluctuations in total salt content are consistent with theoretical work by Maykut and are in phase with mixed layer depth, indicating changes in the mixed layer are controlled by salt flux. Deepening of the mixed layer brings 0.3 kcal cm−2 yr−1 of heat to the surface from the ocean below.
Distribution of hydrothermal manganese over the Juan De Fuca Ridge
Authors: Jones C. J. , Johnson H. P. , Delaney J. R.
Published: February 2008

Bottom waters from five hydrographic stations, spaced equally along a 400‐km section of the Juan de Fuca Ridge north of the Blanco Fracture Zone, contain anomalously high concentrations of total dissolvable manganese (TDM). The two bottom‐most bottles from each hydrocast (∼ 100 to 200 m above bottom) range from 8.3 to 108.9 nmol kg−1 with a median value of 12.0 nmol kg−1. This median is nearly a factor of 10 higher than similar near bottom samples obtained from two off‐axis locations. Analogy to work on the East Pacific Rise implies that hydrothermal activity along the ridge axis is contributing substantially to the manganese content of the water column in this portion of the northeastern Pacific.
Limits on large‐crater production and obliteration on Callisto
Authors: Woronow Alex , Strom Robert G.
Published: February 2008

By comparing results of Monte Carlo simulations of the crater population on Callisto with the observed surface, we demonstrate that the relative dearth of large craters on Ganymede and Callisto, compared with the terrestrial planets, can not be totally ascribed either to craters relaxing or to craters piercing a thin icy crust. Consequently, the population of objects responsible for the heavy bombardment of the jovian system differed markedly from that responsible for the late heavy bombardment of the terrestrial planets.
Measurement of volt/meter vertical electric fields in the middle atmosphere
Authors: Maynard N. C. , Croskey C. L. , Mitchell J. D. , Hale L. C.
Published: February 2008

A test flight for a series of middle atmosphere electrodynamics rockets was launched from Wallops Island, Virginia, at 7:18 EST on July 31, 1980. The mother‐daughter configuration contained a three axis symmetric double probe electric field instrument and a blunt probe on the daughter payload, and a Gerdien condenser and a single axis (vertical) asymmetric double probe electric field instrument on the mother payload. The payloads reached an apogee of 111 km, and data were gathered from all instruments on the downleg. A downward vertical electric field with a maximum amplitude of about 4 V/m was observed in a layer between about 57 and 67 km. The integrated potential across this layer was approximately 20 kV. Conductivity measurements indicated that free electrons were absent from the region of large electric fields; however, the decrease in conductivity was insufficient to maintain vertical current continuity through the layer. These results establish the existence of large mesospheric electric fields, supporting previous results from single axis measurements.
A case of correlation between Rn anomalies and seismic activity on a volcano (Vulcano Island, Southern Tyrrhenian Sea)
Authors: Del Pezzo E. , Gasparini P. , Mantovani M. S. M. , Martini M. , Capaldi G. , Gomes Y. T. , Pece R.
Published: February 2008

A factor of 10 increase in the Rn concentration in a shallow aquifer forerunning a shallow seismic swarm was observed at the island of Vulcano (Aeolian island arc). The peak of Rn anomaly preceded by about one month the seismic swarm, which had a cumulative magnitude of 2.1. The time lag between the two phenomena is much longer than expected, given the small energy released by the swarm. The observed phenomena may not have a direct cause‐effect relationship, but they both can be a consequence of volcanic phenomena.
Elastic thickness of the Venus lithosphere estimated from topography and gravity
Authors: Cazenave Anny , Dominh Kien
Published: February 2008

The very close correlation observed on Venus between topography and gravity on a regional scale is clearly related to the isostatic compensation of the topographic loads. Observed gravity anomalies over topographic features of moderate lateral extent, located in the equatorial region (0° to 40° N latitude and 10° W to 60° E longitude) are somewhat larger than those computed with a model of local isostatic compensation (of Airy type). They may rather be explained by a model of compensation including elastic forces within the lithosphere which contribute to support topographic loads through elastic stresses. We have applied the theory of lithospheric flexure : to explain in wavelength and in amplitude the observed gravity anomalies, a flexural rigidity of ∼ 4 × 1028dyne cm has been estimated for the Venus lithosphere in the rolling plains province. This value is very low compared to the oceanic terrestrial lithosphere (ranging from ∼ 1028dyne cm near ridge crests to ∼ 2 × 1031dyne cm near subduction zones). The corresponding thickness of the elastic upper layer able to maintain elastic stresses for long time duration is ∼ 7.5 km. This value may not be representative of the entire Venus lithosphere.
Radiometric and paleomagnetic evidence for the Emperor reversed polarity event at 0.46 ± 0.05 M.Y. in basalt lava flows from the eastern Snake River Plain, Idaho
Authors: Champion Duane E. , Dalrymple G. Brent , Kuntz Mel A.
Published: February 2008

K‐Ar and paleomagnetic data from cores through a sequence of basalt flows in the eastern Snake River Plain provide evidence for a brief (0.005 to 0.01 m.y.) reversal of the geomagnetic field 0.46 ± 0.05 m.y. ago. This reversed polarity event has also been found in sea‐floor magnetic anomalies and in sediment cores and is probably the Emperor event of Ryan [1972].
Spectral studies of F region irregularities in the auroral zone
Authors: Hanuise C. , Villain J. P. , Crochet M.
Published: February 2008

Auroral F region irregularities have been studied with the HF coherent radar system SAFARI at wavelengths of 10.5 and 7.0 meters. Their Doppler spectra exhibit large spatial and temporal variations which indicate that the phase velocity is related to the motion of the bulk plasma. This observation agrees with a production by low energy precipitations or plasma instabilities like cross‐field instability or current‐convective instability. Coordinated ground‐based and satellite measurements are necessary to conclude definitely on the origin of these irregularities.
The stimulation of auroral kilometric radiation by Type III solar radio bursts
Authors: Calvert W.
Published: February 2008

It has been found that the onset of auroral kilometric radiation (AKR) frequently coincides with the arrival of type III solar radio bursts. Although the AKR onsets are usually abrupt and appear to be spontaneous, they sometimes develop from a discrete frequency near the leading edge of a type III burst or sometimes occur at progressively lower frequencies following that edge. From this, and the absence of the related solar electrons in specific cases, it was concluded that the incoming type III waves were sometimes responsible for stimulating auroral kilometric radiation. It was estimated that intense, isolated type III bursts were capable of stimulating AKR roughly one third of the time, and that at least ten percent of the observed AKR onsets could be attributed to these and weaker bursts, including some barely detectable by the ISEE plasma wave receivers.