bluuebunny/crossref_metadata_2025 huggingface dataset:
The mass of Phobos from Viking flybys
Authors: Christensen E. J. , Born G. H. , Hildebrand C. E. , Williams B. G.
Published: February 2008

The mass of the Martian satellite Phobos has been determined by processing radiometric tracking data obtained from the Viking‐1 spacecraft during a series of 14 near encounters which occurred in February 1977. Distances of closest approach ranged from 89 to 213 km from the center of mass of the satellite. Our best estimate for the gravitational constant, GM, of Phobos is (6.6 ± 0.8) × 10−4 km³/s². The corresponding density of Phobos based on a volume estimate of 4800 ± 960 km³ from Mariner 9 imaging is 2.0 ± 0.5 gm/cm³.
VLF transmission induced slot electron precipitation
Authors: Vampola A. L.
Published: February 2008

Analysis of electron observations in the drift and bounce loss cones of the slot region of the magnetosphere indicates that the predominant mode in which electrons in the 100 to 400 keV energy range arrive in the drift loss cone is via discrete events. These events are usually traceable back to the vicinity of a high‐power‐level VLF transmitter. No gradual buildup of electron flux, proceeding eastward from the South Atlantic Anomaly, is observed. Estimates of the loss rate due to the discrete events show that this process can result in a depletion of 50% per day of the electron flux in the slot region. The wave‐particle interaction probably occurs relatively low on the field line ( ≈ 30° to 50°) because of the relationship of particle energies and wave frequencies involved. Additional scattering of the particles near the equator, either by power‐line harmonic emissions or naturally occuring ELF hiss, may be required to transport the particles to the lower interaction region.
Midlatitude seasonal measurements of stratospheric acidic chlorine vapor
Authors: Lazrus A. L. , Gandrud B. W. , Greenberg J. , Bonelli J. , Mroz E. , Sedlacek W. A.
Published: February 2008

Stratospheric acidic chlorine vapors were sampled up to 36 km by means of base‐impregnated filters. The results do not reveal a measurable seasonal variability. The composite curve indicates a maximum of 0.8 ppbv at 24 km, decreasing to a minimum of 0.5 ppbv at about 31 km. The concentration then increases with altitude to 1.0 ppbv at 36 km.

Laboratory simulation tests yield collection efficiencies of 80% or more for chlorine nitrate, and 100% for hydrochloric acid vapor. However, the concentration of acidic chlorine agrees well with spectrometrically determined concentrations of hydrochloric acid at 25 km and below. This suggests that large concentrations of chlorine nitrate are not present, though photochemical models predict similar concentrations for both chlorine nitrate and hydrochloric acid vapor at 25 km.
Some simple expressions for the probability of failure of a finite reservoir with Markovian input
Authors: Pegram Geoffrey G. S.
Published: February 2008

In a previous paper the writer derived an explicit expression for the probability of failure of a discrete reservoir fed by a Markovian input. This is now simplified to expressions for particular cases which are characterized by the ratio of mean input to target draft. It is shown that the expressions yield some classical results in Stochastic Reservoir Theory.
Paleomagnetism of Suiko Seamount, Emperor Seamount Chain
Authors: Kodama K. , Uyeda S. , Isezaki N.
Published: February 2008

Using data from a topographic and magnetic survey, the magnetization vector of Suiko seamount near the middle of the Emperor seamount chain (44.5°N, 170°E) was calculated. An inclination of −31° ± 9° and a declination of 213° ± 9° was found, although the goodness ratio is poor (R = 1.1). The paleolatitude thus found (17° ± 5°) is significantly different from its present latitude, supporting the theory that the Emperor‐Hawaii chain has been formed by the Hawaiian hot spot. Magnetization of the seamount is reversed, agreeing with the recent DSDP results.
The importance of electron heat conduction in the energy balance of the F‐region
Authors: Hoegy Walter R. , Brace Larry H.
Published: February 2008

Further analysis of the ionospheric electron heat balance using measurements by Atmosphere Explorer C has shown that electron heat conduction is important not only in the upper F‐region but throughout the lower ionosphere as well. The discrepancy between local heating and cooling rates reported by Brace et al., using similar AE‐C data, has been removed in the present study by selecting middle latitude passes in which horizontal gradients in Te are minimized, thus permitting the vertical or field aligned gradients to be resolved for use in the heat conduction equation. The inclusion of heat conduction consistently improves the agreement between theoretical and experimental Te6 profiles. Accordingly, poor agreement is obtained when using AE‐C data at low latitudes where large scale horizontal gradients in Te and Ne preclude the resolution of field‐aligned gradients in Te. Thus it would appear that current electron heating and cooling rates are consistent with the AE‐C observations. This study was limited to the effects of EUV heating at solar minimum, thus we do not imply that the electron energy balance is understood globally. Heating at high latitudes and nocturnal heating require further study.
Mare Crisium: Regional stratigraphy and geologic history
Authors: Adams John B. , Head James W. , McCord Thomas B. , Pieters Carle , Zisk Stanley
Published: February 2008

Spectral reflectance measurements of five Luna 24 samples and new telescopic reflectance spectra of 10‐20 km areas of seven sites in Mare Crisium have been used to calibrate multispectral images of mare units. Based on these data, three major mare units are defined in the Crisium basin and their stratigraphy is interpreted. The oldest mare unit is exposed in the ejecta of the craters Picard and Peirce and along the outer edge of the southeastern part of the basin. The next younger unit includes the Luna 24 site and generally follows a topographic annulus along the basin margin. The youngest mare unit occupies the central part of the basin. It is concluded that subsidence occurred throughout the emplacement of mare units, including extensive warping and downfaulting of the inner part of the Crisium basin.
Stratospheric ozone measurement with an infrared Heterodyne spectrometer
Authors: Abbas Mian M. , Kostiuk Theodor , Mumma Michael J. , Buhl David , Kunde Virgil G. , Larry W. Brown
Published: February 2008

A stratospheric ozone absorption line in the 10 µm band has been measured and resolved completely, using an infrared heterodyne spectrometer with a spectral resolution of 5 MHz (0.000167 cm−1). The vertical concentration profile of stratospheric ozone is obtained through an analytical inversion of the measured spectral line profile. The absolute total column density was 0.32 ± 0.02 cm‐atm with a peak mixing ratio occurring at ∼ 24 km. The (7,1,6) ‐ (7,1,7) O3 line center frequency was found to be 1043.1772 ± 0.00033 cm−1, or 420 ± 10 MHz higher than the P(24) CO2 laser line frequency.
On the relationship of ∼3 mHz (Pc5) electric, magnetic, and particle variations
Authors: Maclennan C. G. , Lanzerotti L. J. , Hasegawa A. , Bering E. A. , Benbrook J. R. , Sheldon W. R. , Rosenberg T. J. , Matthews D. L.
Published: February 2008

The first evidence is presented of associated magnetic field, electric field, and electron precipitation fluctuations from ground‐based and balloon‐based measurements. The magnetic field fluctuations are produced by magnetohydrodynamic waves of approximately 5 min period in the earth ’s magnetosphere. The electric, magnetic, and particle variations are observed to be in close phase relationship when the measurements are made near the resonance region of the magnetospheric waves. When the resonance region is not close to the location of the electric field observations no clear wave‐associated electric field or particle variations are observed. The observed wave frequency is ∼3 times lower than the fundamental Alfvén resonance frequency. This may arise from a Doppler shift of the resonant frequency by a diamagnetic plasma drift. The height‐integrated ionospheric Pedersen conductivity deduced from the simultaneous electric and magnetic field variations corresponds to approximately 30 mho.
Limitations of ophiolite complexes as models for the magnetic layer of the oceanic lithosphere
Authors: Levi Shaul , Banerjee S. K. , Beske‐Diehl S. , Moskowitz B.
Published: February 2008

We propose that only those ophiolite complexes whose magnetic properties and metamorphic grade correspond to comparable stratigraphic units of in‐situ oceanic crust should be used for modeling the magnetic properties of the oceanic lithosphere. Because drilling of the igneous oceanic crust by the Deep Sea Drilling Project (DSDP) has penetrated a maximum of 0.6 km, only the upper extrusives (pillow basalts and associated flows) of an ophiolite complex can be used in this direct comparison. Previously published and new data of submarine basalts are used for establishing minimum constraints for the magnetic properties of the extrusive rocks of ophiolite complexes. These criteria are:

1) initial Curie points (Tc) should be between 100° ‐ 450°C (for Tc ⪞ 200° C the saturation magnetization versus temperature curves should be irreversible);

2)
(intensity of magnetization) > 1×10−4 gauss (1×10−1 Am−1);

3)
(ratio of remanent to induced magnetization) > 1;

4) alteration of the upper extrusives should not exceed zeolite facies metamorphism.

These necessary but not sufficient criteria were applied to five ophiolite complexes, of which only two satisfied all the requirements. The remaining ophiolite complexes were probably subjected to a metamorphic event either during or subsequent to their original emplacement as part of the oceanic lithosphere.
Preliminary results on 27‐day solar rotation variation in stratospheric zonal winds
Authors: Nastrom G. D. , Belmont A. D.
Published: February 2008

Zonal wind variations corresponding to the sun's rotation period have been found by cross‐spectral analysis of 10.7 cm solar flux and rocketsonde data, 25‐65 km, at stations mostly near 80°W for 1960‐1976. The amplitudes of the 27‐day variation have maxima near the stratopause near 25°N and 50°N which are nearly out of phase with each other. These results are in accordance with the land‐sea heating planetary wave model recently proposed by Volland, but an alternative explanation could be direct UV heating of the upper stratosphere. Large changes are found in the 27‐day variation between periods of moderate and low solar activity.
Fast wave evanescence in the solar corona
Authors: Hollweg Joseph V.
Published: February 2008

Using a horizontally stratified model of the solar atmosphere, we argue that appreciable fast wave fluxes of solar origin may not be able to propagate into the solar wind. Fast waves may thus not be a significant source of extended heating and acceleration of the solar wind. This conclusion could be altered by nonlinearity and/or by complex structure of the solar atmosphere, however.
High β plasma in the dynamic Jovian current sheet
Authors: Walker Raymond J. , Kivelson Margaret G. , Schardt Alois W.
Published: February 2008

The equatorial current sheet, which Pioneer 10 repeatedly encountered on its outbound pass through the Jovian magnetosphere, frequently was associated with intense fluxes of energetic protons. Simultaneous observations of the changes in the energetic proton flux and in the magnetic field magnitude demonstrate that the current sheet is embedded in a high β plasma in which high energy (> 60 keV) ions frequently are the dominant constituents. Large differences in the plasma temperature and the thickness of this plasma sheet between encounters only 10 hours apart indicate that the Jovian plasma sheet is very dynamic on a time scale of hours. Occasional observations of significant temporal variations in the magnetic field and particle populations during periods within the plasma sheet may represent in situ observations of Jovian magnetic disturbances. Comparison with previous observations suggests that low energy (≤ 5 keV) plasma contributes less than 3% to the current sheet energy density.
High correlations between variations in monthly averages of solar activity and total atmospheric ozone
Authors: Blackshear W. T. , Tolson R. H.
Published: February 2008

Estimates of the ozone total columnar content, derived from Nimbus IV IRIS data, have been analyzed to estimate monthly averages of the total global atmospheric ozone. Over a 9‐month interval, the variation in this monthly average is approximately an order of magnitude greater than its associated uncertainty, and has characteristics in common with variations in the 10.7 cm solar flux, the Zurich sunspot number, and the total solar Lyman α flux. The highest correlation, 0.94, exists between the variation in the total Lyman α flux and the variation in the estimated total atmospheric.ozone.
Stratospheric NO2 in the Antarctic winter
Authors: Noxon J. F.
Published: February 2008

Shipboard measurements of stratospheric NO2 between 42° and 55° in the southern hemisphere during July 1978 show an abrupt change in the daytime abundance near 50°S similar to that seen in the northern winter hemisphere. The antarctic transition is the sharper, possibly as a result of higher stability in stratospheric zonal flow.
Microstructures in low temperature dolomites
Authors: Reeder R. J. , Wenk H. R.
Published: February 2008

Electron microscopy of sedimentary dolomite reveals heterogeneous microstructures on a 100 ‐ 300Å scale which we interpret as compositional modulations. Electron diffraction patterns contain a new type of superstructure reflection which effectively doubles the a axis. These findings suggest the presence of a new phase in low temperature calcian dolomite rocks.
Measurement of hydroxyl concentration in boundary layer air by monitoring CO oxidation
Authors: Campbell Malcolm J. , Sheppard John C. , Au Bernard F.
Published: February 2008

The local 14CO oxidation rate and the corresponding OH radical concentration in boundary layer air have been measured at several sites. Measured OH concentrations range from 3×105 to 4×106 cm−3. We describe the method and discuss the reliability of the measurements.
Detrital remanent magnetisation in five slowly redeposited long cores of sediment
Authors: Barton C. E. , McElhinny M. W.
Published: February 2008

1½m cores of fine grained organic lake sediments gradually redeposited over a period of 9 months accurately track the direction of the ambient magnetic field. Inclination errors are not significant and the delay between deposition and acquisition of a stable remanence is less than 2 days. Only a small degree of post‐depositional grain reorientation occurs after this interval. The newly formed deposits are sufficiently cohesive to be subsampled without recourse to forced compaction and retain a stable remanence with water contents as high as 90% by volume (∼85% by weight). Use of the results to calibrate the simple relative paleointensity estimate Q = NRM/susceptibility for the natural sediments can lead to variable results even in similar sequences where the NRM is a DRM.
Paleomagnetic study of sediments around the Komyoike Volcanic Ash Horizon in Osaka Group, Senpoku Area, Osaka Prefecture, Japan
Authors: Maenaka Kazuaki
Published: February 2008

The Osaka Group is typical of the Plio‐Pleistocene Series in Japan. The correlation of paleomagnetic stratigraphy and biostratigraphy gives a clear picture of the Quaternary history of the Group. The Komyoike volcanic ash layer distributed only in the Senpoku area, in the southern part of Osaka Prefecture is shown to have normal polarity at 1.1 million years (fission track age). The remanent magnetizations of more than one hundred oriented samples collected in sequence from the out‐crop sediments intercalated with the Komyoike volcanic ash bed were measured. Paleomagnetic results after magnetic cleaning show that the sedimentary sequence is divided into three distinct zones by changes in the remanent polarity.
On the inversion of travel times
Authors: Garmany Jan
Published: February 2008

In a vertically heterogeneous medium in which velocity increases with depth, the delay time function and, consequently, the distance and travel time functions are related linearly to depth as a function of slowness. Since all travel time inversions using surface measurements of travel time and distance require the removal of the effects of low velocity zones, we may assume this linearity always holds. The highly developed theory of linear inversion is thus applicable to the inverse travel time problem.
Spectroscopy of the extreme ultraviolet dayglow at 6.5Å resolution: Atomic and ionic emissions between 530 and 1240Å
Authors: Gentieu E. P. , Feldman P. D. , Meier R. R.
Published: February 2008

EUV spectra (530‐1500Å) of the day airglow in up, down and horizontal aspect orientations have been obtained with 6.5Å resolution and a limiting sensitivity of 5R from a rocket experiment. Below 834Å the spectrum is rich in previously unobserved OII transitions connecting with 4So, ²Do, and ²Po states. Recent broad‐band photometric observations of geocoronal HeI 584Å emission can be understood in terms of the newly observed OII emissions. The OI 989Å and OI 1304Å emissions exhibit similar dependence on altitude and viewing geometry with the OI 989Å brightness 1/15 that of OI 1304. Emission at 1026Å is identified as geocoronal HI Lyman‐β rather than OI multiplet emission and observed intensities agree well with model estimates. An unexpectedly high NI 1200/NI 1134Å brightness ratio is evidence of a significant contribution from photodissociative excitation of N2 to the NI 1200Å source function.
The energetics of the ionosphere of Venus: A preliminary model based on Pioneer Venus observations
Authors: Cravens T. E. , Nagy A. F. , Brace L. H. , Chen R. H. , Knudsen W. C.
Published: February 2008

A model of the energy balance of the dayside ionosphere of Venus is presented. The coupled energy equations for electrons and ions are solved numerically and the calculated temperatures are compared with temperatures measured by instruments on the Pioneer Venus Orbiter. Neutral and ion density profiles consistent with those measured by various Pioneer Venus experiments are used in the model. It was found that using standard EUV sources and thermal conductivities the calculations produce temperatures that are much lower than the measured ones. Consequently, further calculations were performed in which 1) the thermal conductivities were inhibited by means of an almost horizontal magnetic field and/or 2) heat inflow into both the electron and ion gas at the top of the ionosphere was assumed due to the solar wind interaction. It was found that the calculated and measured temperatures were in reasonably good agreement if the thermal conductivities were inhibited by a near horizontal field of about 10 gammas and if the electron and ion heat fluxes were taken to be 4 × 109 eVcm−2s−1 and 4 × 107 eVcm−2s−1/ respectively.
A model of the variability of the Venus ionopause altitude
Authors: Wolff R. S. , Goldstein B. E. , Kumar S.
Published: February 2008

A model for the variability of the Venus ionopause as a function of solar wind dynamic pressure and EUV flux during quiescent solar wind conditions is presented. The radio occultation measurements of the Venus ionopause from Mariner 5, 10 and Venera 9, 10 spacecraft, as well as recent in situ Pioneer Venus measurements are interpreted in terms of this model. An ionospheric model consistent with observations in the 400 ‐ 1000 km region is predominantly O+ with densities ∼104 cm−3 and (Te + Ti) ∼4500 ‐ 6500°K. For ionopause measurements below 400 km the ionosphere appears severely compressed and density and temperature profiles cannot be simply described, although a strong correlation with solar wind dynamic pressure is observed. Possible effects of IMF direction switching on the dynamics and structure of the ionosphere are also considered and compared with available ionopause data.
On the detection of the polarization states of Pc micropulsations
Authors: Olson John V. , Samson John C.
Published: February 2008

We demonstrate the ease in construction and the utility of detectors sensitive to particular micropulsation characteristics. The detector algorithms are simple and hence they consume little computer time. Yet they are sophisticated enough to sense unique pulsation states. Detection of HD plane polarization is shown as an especially simple case. As an example of the wider utility of these detectors we have followed the movement of a resonant region across a single ground based magnetic station during a large amplitude Pc5 event. The clarity of the results points toward a more complete use of Pc micropulsations as magnetospheric diagnostics.
[Correction to] “Reply to 'Isotopic composition of the anomalous xenon in the Murchison Meteorite'” by Stephen P. Smith""
Authors: Srinivasan B. , Anders Edward
Published: February 2008

This paper originally appeared in Vol. 6, No. 1, 59–61, 1979. Due to a production error in paste‐up, we have republished the first page. Our sincere apology to the authors and readers.

Smith's reinterpretation of the data of Srinivasan and Anders is misleading, because it treats a 4‐component system as a 2‐component system, using a pseudocomponent whose existence, let alone constancy, is at variance with extensive data on Murchison and Allende. The derived "well defined" spectra are of doubtful significance, being based on the fit of a straight line to a curving set of 4 points.

Our original identification of an s‐process component remains valid, but its purity ‐ never claimed by us, contrary to statements by Smith ‐ remains undetermined.
ISIS 1 observations at the source of auroral kilometric radiation
Authors: Benson Robert F. , Calvert Wynne
Published: February 2008

Observations of auroral kilometric radiation (AKR) are made by ISIS 1 in the source region. The radiation is found to be generated in the extraordinary mode just above the local cut‐off frequency and to emanate nearly perpendicular to the magnetic field. It occurs within local depletions of electron density, where the ratio of plasma frequency to cyclotron frequency is less than 0.2. The density depletion is restricted to altitudes above about 2000 km, and the upper AKR frequency limit corresponds to the extraordinary cutoff frequency at this altitude. AKR is observed from ISIS 1 above the nighttime auroral zone over a wider extent in longitude than in latitude with an intense source region observed most often near 2200 LMT and 70° invariant latitude. It is directly related to inverted V electron precipitation events with an electron‐to‐wave energy conversion efficiency of the order of 0.1 to 1%.
A new concept for the daytime magnetosphere of Venus
Authors: Johnson Francis S. , Hanson William B.
Published: February 2008

The Pioneer Venus magnetic field measurements have suggested the possibility of a different type of interaction between the solar wind and the ionosphere of a non‐magnetized planet than has been envisioned in the past. An unexpected aspect of the observations is that the magnetic field of the shocked solar wind does not penetrate the ionosphere; thus it appears that the ionosphere acts approximately as a superconductor, excluding any substantial penetration of interplanetary magnetic field. The ionosphere on the day side is terminated sharply at an ionopause and is magnetized weakly or not at all. Just beyond the ionopause is a magnetized region with relatively little plasma, and whose magnetic pressure is approximately equal to the impact pressure of the solar wind. This suggests to us the possibility of an interaction where the current system associated with the region of enhanced magnetic field flows along the ionopause and is closed by currents in the shocked solar wind plasma, where the
forces act to slow down the plasma approaching the stagnation region and accelerate the plasma flowing away from it. With this concept, the lack of magnetic constraint in the ionosphere would allow ionospheric plasma to flow freely from the day to the night side and this flow, whose magnitude should depend inversely on the solar wind pressure, could probably maintain the nighttime ionosphere.
Volatiles in chainpur chondrules
Authors: Grossman Jeffrey N. , Kracher Alfred , Wasson John T.
Published: February 2008

A study of individual chondrules in the Chainpur (unequilibrated) LL3 chondrite revealed order‐of‐magnitude variations in volatile element concentrations, with maxima ∼2X and minima ∼0.1X whole‐rock concentrations. In no chondrule were concentrations of all volatiles lower than 0.5X bulk values; only one volatile, Ge, had an observed chondrule/bulk ratio lower than 0.15. Volatile elements differing in geochemical behavior tended to vary randomly; correlated variations were observed only for those elements inferred to occupy similar mineral sites. Although metamorphic redistribution could produce similar observations, variations in Co and Ni in kamacite show that metal in chondrule interiors have not approached equilibrium, and it appears that postformational elemental redistribution has mainly altered siderophile concentrations in surface metal grains, and has probably left ionic species relatively unaltered. Etching to remove 3–5% of the chondrule mass selectively dissolved siderophiles; the volatiles Zn and Na were enhanced by small factors relative to nonvolatile Cr in the etch, but a large enhancement of Cd involved about 20% of total Cd. This portion of the Cd may have been present as a late nebular condensate. If metamorphic redistribution of nonsiderophile volatiles was negligible, their high concentrations are inconsistent with chondrule formation by direct condensation. Models involving sudden melting of preexisting solids can explain the observations but require rapid cooling to prevent volatile loss.
H+ and He+ + in the dawnside magnetosheath
Authors: Peterson W. K. , Shelley E. G. , Sharp R. D. , Johnson R. G. , Geiss J. , Rosenbauer H.
Published: February 2008

Mass and energy analyses of energetic ions in the dawnside magnetosheath have been made by the energetic ion composition experiment on the ISEE‐1 spacecraft over the energy range 10 eV/e ⩽ E/Q ⩽ 17 keV/e. The significant observations are: The bulk flows of the H+ and He+ + components determined from first moments of the distributions averaged over several minutes are equal within the uncertainties of the measurement. The H+ and He+ + distributions are similar in that they both show temperature anisotropies with T⊥ ⩾ T∥; however, the distributions are not well characterized by temperatures derived from second moments. In at least one case high energy tails of both distributions can be characterized by an additional higher temperature component. The major difference between the H+ and He+ + distributions is the depletion of the low velocity (in the center of mass frame) part of the He+ + distributions, relative to the H+ distributions.
The structure and the magnetic field of Uranus
Authors: Torbett Michael , Smoluchowski Roman
Published: February 2008

The two‐layer model of Uranus is recalculated using a rotation period of 24 rather than 10.8 hours and also the melting temperatures of H2O and of the constituents of the core are evaluated. It appears that the core is solid and the H2O‐containing mantle is liquid. The conductivities of H2O, "metallic" H2 and metallic H are roughly in the ratio of 1∶10²∶104 so that the convective velocities required for the operation of a dynamo would have to be about 10, 10−1 and 10−3cm sec−1 respectively. The very low thermal flux from Uranus suggests that, unless a precessional dynamo is invoked, metallically conducting H2or metallic hydrogen has to be present in the mantle.
A method to determine the duration of quiescence in a seismic gap
Authors: Acharya H. K.
Published: February 2008

The concept of seismic gap has been developed in recent years to identify areas which have not been active in the past few years and arethereforeconsidered to have potential for large earthquakes in the future. I propose an empirical method to determine the duration of quiescence in seismic gap by estimating slip which will occur when the gap ruptures. This method depends on rate of plate motionlength of seismic gapand empirical relationship between rupture length and seismic moment. For earthquakes which have occurred in previously identified gaps and for which duration of quiescence is knownthis method predicts quiescence time to within about 10 yearswhichconsidering errors in plate motion rateslength of seismic gapand empirical relationship involvedis very good.
Is unusual animal behavior observed before earthquakes? Yes and no
Authors: Lott Dale F. , Hart Benjamin L. , Verosub Kenneth L. , Howell Mary W.
Published: February 2008

Following two moderate earthquakesreports of the behavior of animals prior to the earthquakes were gathered using a standardized interview schedule. This schedule was developed to maximize the reliability and validity of the reports through the application of accepted social science methodology. Interviews with 50 households near WillitsCaliforniaproduced 17 reports of unusual animal behavior prior to that earthquake. Only one of thirty‐five interviewees who experienced a similar earthquake near OvandoMontanareported unusual animal behavior prior to the earthquake. This difference in the frequency of positive reports and the content of the positive reports from Willits support the inference that a number of animals at Willits were responding to physical precursors which were absent at Ovando. The behavior reported at Willits was unusual in the sense that there was no immediate explanation for itbut it was not bizarre. On the contraryit was always behavior typical of that species when motivated by generalized anxiety. Unusual behavior was often reported in only one or a few animals at a particular location so that even at Willits most animals were described as having behaved normally.
A flash photolysis resonance fluorescence investigation of the reaction OH + CH3CCl3 → H2O + CH2CCl3
Authors: Kurylo Michael J. , Anderson Philip C. , Klais Odo
Published: February 2008

The absolute rate constant for the reaction OH + CH3CCl3 → H2O + CH2CCl3 has been determined by the flash photolysis resonance fluorescence technique from 253 to 363K. The results are used to recommend the Arrhenius expression in units of cm³ molec−1s−1. Use of this equation with atmospheric observational data on methyl chloroform nearly doubles the predicted tropospheric OH reaction sink strength for the removal of important atmospheric gases whose lifetimes are controlled by OH. Comparison of the results reported here with previously reported literature values indicates a strong interference of olefinic impurities on the past investigations.
Electron distribution functions associated with electrostatic emissions in the dayside magnetosphere
Authors: Sentman D. D. , Frank L. A. , Gurnett D. A. , Kurth W. S. , Kennel C. F.
Published: February 2008

Electron distribution functions constructed from ISEE‐1 dayside observations of low energy magnetospheric electrons at low latitudes are presented. We choose examples corresponding to three distinct types of odd half harmonic electrostatic emissions observed by the plasma wave experiment on ISEE‐1and occurring between the electron cyclotron frequency fce and the upper hybrid frequency fUH. These are (a) intense (3/2)fce emissions; (b) weak (n + 1/2)fce noise; and (c) intense fUH waves at (9/2)fce. No loss cone‐like features are discernable in any of the distribution functions at the level of the instrument angular resolution. Howevera weak ringlike featureconsisting of a small localized region in velocity space near 4 × 109 cm s−1 and a = 90° where ∂f/∂v⊥ > 0is found in the distribution function corresponding to the occurrence of the intense fUH noise. This ringlike feature may provide a source of free energy to drive the fUH instability. The apparent absence of detectable loss cones in the cases of the intense (3/2)fce and fUH emissions is consistent with the expectation that these plasmas are roughly at the level of strong pitch angle diffusion computed from the observed wave intensities at these times. Although each of the distribution functions displays a temperature anisotropy T⊥ > T∥the anisotropies are too small to excite any of the odd half harmonic emissions.
Actinometric measurements and theoretical calculations of j(O3)the rate of photolysis of ozone to O(¹D)
Authors: Dickerson R. R. , Stedman D. H. , Chameides W. L. , Crutzen P. J. , Fishman J.
Published: February 2008

A new experimental technique measures j(O3‐O(¹D))the rate of solar photolysis of ozone to singlet oxygen atoms: O3 + hν → O2 + O(¹D). A flow actinometer carries dilute O3 in N2O into direct sunlight where the O(¹D) formed reacts with N2O to form NO which chemiluminescence detectswith a time resolution on the order of one minute. Measurements indicate a photolysis rate of 1.2 (± .2) × 10−5 s−1 for a cloudless sky45° zenith angle0.345 cm ozone column and zero albedo. Ground level results (elevation 1.8 km) compare with theoretical calculations based on the UV actinic flux as a function of ozone column and solar zenith angle.
Photodissociation of nitric oxide in the mesosphere and stratosphere: Simplified numerical relations for atmospheric model calculations
Authors: Nicolet Marcel
Published: February 2008

A numerical method is presented for modeling the photodissociation of nitric oxide in the mesosphere and the relevant part of the stratosphere. By using the following simple formula it is possible to obtain sufficiently realistic photodissociation rates which are in reasonable agreement with detailed calculations. In the stratospherethe effects of ozone absorption and of molecular nitrogen de‐excitation must be introduced.
Average daily magnetic variation pattern and its equivalent current pattern determined by the IMS Alaska Meridian Chain of observatories
Authors: Akasofu S.‐I. , Romick G. J. , Ahn Byung‐Ho , Kroehl H. W. , Allen J. H. , Kisabeth J.
Published: February 2008

The average daily magnetic variation pattern and its equivalent current pattern determined by magnetometer data from the IMS Alaska meridian chain of observatories for the period between March 9 and April 271978 are presented in the form of polar plots (magnetic latitude‐MLT coordinates). The corresponding equivalent current pattern shows the so‐called ‘two‐cell’ pattern. Howeverthe computed ionospheric current pattern using the method developed by Kisabeth (1979) has little resemblance to the ‘two‐cell’ patternindicating that the main pattern of the ionospheric currents must be fed by field‐aligned currents.
Position and shape of the Venus bow shock: Pioneer Venus Orbiter observations
Authors: Slavin J. A. , Elphic R. C. , Russell C. T. , Wolfe J. H. , Intriligator D. S.
Published: February 2008

In this study magnetometer data from the Pioneer Venus Orbiter is used to examine the position and shape of this planet's bow shock. Utilizing crossings identified on 86 occasions during the first 65 orbits a mean shock surface is defined for sun‐Venus‐satellite angles of 60‐110°. Both the shock shape and variance in location are found to be very similar to the terrestrial case for the range in SVS angle considered. Howeverwhile the spread in shock positions at the earth is due predominantly to the magnetopause location varying in response to solar wind dynamic pressureionopause altitude variations can have little effect on total obstacle radius. Thusthe Cytherean shock is sometimes observed much closer to or farther from the planet than previously predicted by gasdynamic theory applied to the deflection of flow about a blunt body which acts neither as source nor sink for any portion of the flow.
Time evolution of ion contaminant clouds at geosynchronous orbit
Authors: Garrett H. B. , Forbes J. M.
Published: February 2008

The exploitation of geosynchronous orbit will bring with it perturbations of the ambient plasma environment by man‐made effluents. In this paper, the creation, ionization, and subsequent transport of an artificially produced contaminant cloud in the immediate vicinity of a spacecraft at geosynchronous orbit will be examined. The theory predicts the probability of observing xenon from the SCATHA (P78‐2) SC4 xenon beam experiment by GEOS II. Estimates will also be presented for the ionization cloud expected from projected systems such as large space stations (air leakage) or a solar power satellite (argon thrusters).
Periodicities in the Jovian magnetosphere: Magnetodisc models after Voyager
Authors: Carbary J. F.
Published: February 2008

The Voyager‐1 and 2 outbound observations of periodic double‐peak flux maxima (which mark encounters with the magnetodisc) are separated into two distinct branches ‐ a "leading" branch (N → S disc crossings) and a "trailing" branch (S → N disc crossings). On a plot of System III (1965.0) longitude vs. radial distance, the leading branch has a positive slope (∼ 1.2°/RJ) and the trailing branch has a relatively flat slope (∼ 0.3°/RJ). The two branches meet at ∼ 80‐100 RJ, beyond which periodic single peak or closely‐spaced multiple peaks are generally observed. This paper examines this structure using the 3 principal disc models which have emerged to explain periodicities in the Jovian magnetosphere: (1) the rigid magnetodisc model, (2) the bent or warped magnetodisc model, and (3) the wavy magnetodisc model. The rigid disc model does not allow for the merging of the double‐peak structure into a single‐peak structure, and the bent disc model cannot explain the phase lag of the leading peaks. Both the merging of the peaks and the phase asymmetry can be explained by a wavy‐disc model in which the wave amplitude is fixed. The disc surface is then described in Jovigraphic cylindrical coordinates by z = −ro tan α cos [ϕ + Ω (r − ro) /Vo] where ro ≈ 20 RJ, α ≈ 10.7° is the dipole axis tilt angle, Ω = 2π/10 hr−1 is the angular speed of Jupiter's rotation, and Vo ≈ 40 RJ/hr is the speed of wave propagation. Count rate profiles along the Voyager trajectories may then be reproduced using a simple model in which the rates vary exponentially in radial distance and δz, the distance from the disc surface.
The uppermost mantle P wave velocities beneath Turkey and Iran
Authors: Chen Chu‐Yung , Chen Wang‐Ping , Molnar Peter
Published: February 2008

The uppermost mantle P wave velocities beneath Turkey and Iran were estimated by applying the conventional travel time‐distance relation method to arrival times of well located earthquakes recorded at a few stations. The average uppermost mantle P wave velocity under Turkey is estimated from two stations of the World Wide Standardized Seismograph Network (WWSSN), Istanbul and Tabriz. The data are consistent with a crust of uniform, but poorly determined, thickness and an uppermost mantle P wave velocity of 7.73 ± 0.08 km/s. This velocity is very similar to that for the Aegean Sea and suggests that its structure could be closely related to that beneath Turkey. For Iran, the results calculated from travel times to three WWSSN stations, Meshed, Shiraz and Tabriz, can be explained by a crust dipping toward the south‐southeast at about 1° with an uppermost mantle P wave velocity of 8.0 ± 0.1 km/s. If the crustal thickness were 34 km in the north it would reach about 49 km in the south. Based on these uppermost mantle velocities, the temperature at Moho beneath Turkey is probably close to the melting temperature of peridotite but that beneath Iran is probably lower.
Melt production by viscous dissipation: Role of heat advection by magma transport
Authors: Feigenson Mark D. , Spera Frank J.
Published: February 2008

An energy conservation equation is formulated that balances the heat generated by viscous dissipation in a peridotite simultaneously undergoing partial fusion and penetrative constant shear stress deformation with the heat removed by mobilization and ascent of basaltic magma from the region undergoing deformation. The solution of this parameterized energy equation gives the volume fraction of melt (θ) as a function of time (t) after the initiation of deformation. A stability analysis of the conservation equation shows that stable (θ<100%) or unstable (θ→∞) solutions exist depending on the magnitude of two dimensionless parameters K1/K2 and K3. For geologically reasonable values of K1/K2 and K3, the analysis indicates that peridotitic thermo‐mechanical systems undergoing penetrative deformation at constant shear stress show a two‐stage history. An early stage of growth where θ increases monotonically on a 2 to 3 m.y. time scale eventually is replaced by a steady state regime (constant θ). Typical values of θ lie in the range 3 to 5 volume percent; melting of peridotite to the extent of 20‐30% appears to be precluded by this model.
Dynamic magnetic structure of large amplitude Alfvénic variations in the solar wind
Authors: Lichtenstein B. R. , Sonett C. P.
Published: February 2008

The dynamic structure of large amplitude Alfvénic disturbances of the interplanetary magnetic field (IMF) is examined by transforming one‐hour intervals of Explorers 33 and 35 magnetometer data from the solar ecliptic coordinate system to a coordinate system defined by the principal axes of the variance matrix. Graphic displays of the rotated magnetometer data, in the form of linear time series’ for the field component in the direction of minimum variance and hodographs for the magnetic field vector component in the plane of maximum variance, reveal ordered structure to field components which appear almost random when displayed as time series’ in the solar ecliptic coordinate system. When there is a well defined minimum variance direction, the component of the magnetic field in the plane normal to the direction of minimum variance tends to oscillate with constant magnitude so that the tip of the vector lies on a circular arc. However, the angular motion of the vector appears to be unconstrained. This type of behavior for the IMF satisfies the necessary local conditions for plane large amplitude Alfvén waves. Residual variability of the magnetic field in the direction of minimum variance may be due to the fully three‐dimensional oscillations of the nearly plane waves or a small compressional component associated with fluctuations in the magnetic field magnitude. The different types of angular motion of the magnetic field component normal to the direction of minimum variance may be indicative of the detailed conditions of the solar coronal plasma in the regions generating the Alfvén waves, or some aspect of local generation.
Pulse propagation in media with frequency‐dependent Q
Authors: Brennan B. J.
Published: February 2008

Recent publications have indicated that a significant dependence of the quality factor Q on frequency may occur in the interior of the earth, and thus an analysis of pulse propagation in media with Q dependent on frequency is appropriate. It is shown that a simple scaling law describes the degradation of an initially sharp pulse as it propagates in a linear viscoelastic medium in which Q has a power‐law dependence on frequency. Of particular interest is the variation of the pulse rise time with path, as this parameter may be useful in estimating the Q structure of the earth.
Observations of a free‐energy source for intense electrostatic waves
Authors: Kurth W. S. , Frank L. A. , Ashour‐Abdalla M. , Gurnett D. A. , Burek B. G.
Published: February 2008

Significant progress has been made in understanding intense electrostatic waves near the upper hybrid resonance frequency in terms of the theory of multiharmonic cyclotron emissions using a classical loss‐cone distribution function as a model. Recent observations by Hawkeye 1 and GEOS 1 have verified the existence of loss‐cone distributions in association with the intense electrostatic wave events, however, other observations by Hawkeye and ISEE have indicated that loss cones are not always observable during the wave events, and in fact other forms of free energy may also be responsible for the instability. Now, for the first time, a positively sloped feature in the perpendicular distribution function has been uniquely identified with intense electrostatic wave activity. Correspondingly, we suggest that the theory is flexible under substantial modifications of the model distribution function.
Ions of Jovian origin observed by Voyager 1 and 2 in interplanetary space
Authors: Zwickl R. D. , Krimigis S. M. , Armstrong T. P. , Lanzerotti L. J.
Published: February 2008

Burst‐like and long‐lived ion fluxes (E ≳ 30 keV) of Jovian origin have been observed in interplanetary space by the LECP instrument on the Voyager 1 and 2 spacecraft. Burst (few minute duration) events are observed at distances greater than 0.6 AU (1200 RJ) from Jupiter. These events are highly anisotropic and possess steep energy spectra, while long‐lived (>8 hour duration) events have relatively steady fluxes at low energies, strong anisotropies that decay with time, and a variable high energy component. Both types of events usually display simultaneous onsets and sharp cutoffs for all energies, an excess of atomic number Z ≥ 6 particles compared to solar and interplanetary events, and particle flow directions pointed away from Jupiter along the local interplanetary magnetic field. The origin for the long‐lived events appears to be inside the bow shock of the planet.
Saturn: Tropospheric ammonia and nitrogen
Authors: Atreya S. K. , Kuhn W. R. , Donahue T. M.
Published: February 2008

Photochemical calculations based on recent data on the Saturn temperature structure and Lyman alpha albedo indicate that detectable amounts of gaseous ammonia may exist between 20 and 35 km above the cloud tops. An instrument that might be able to observe this gas is the spectrometer on board the International Ultraviolet Explorer satellite. The calculations also yield a maximum nitrogen mixing ratio at the cloud tops between 1.8×10−10 and 6×10−8 by volume, depending upon the degree of supersaturation of ammonia and hydrazine. Even the lower limit could produce intense emissions if electrical discharges such as those observed on Jupiter by Voyager are also present on Saturn, or if high energy particles penetrate to the Saturnian troposphere.
The UV dayglow 2, Lyα and Lyβ emissions and the H distribution in the mesosphere and thermosphere
Authors: Anderson D. E. , Feldman P. D. , Gentieu E. P. , Meier R. R.
Published: February 2008

Rocket observations of the Lyman α and Lyman β day airglow are analyzed using a nonisothermal spherical model of the radiation field. This new model provides, for the first time, a method of determining atomic hydrogen densities in the mesosphere and thermosphere. Interpretation of Lyman α data taken between 80 and 260 km is consistent with current mesospheric and thermospheric models, with H density equal to 1.9 × 107 cm−3 at 100 km. Analysis of 1025A data suggests that the emission is dominated by Lyman β with perhaps as much as a 30% contribution from OI 1027.
Direct computation of the sensible heat flux
Authors: Watson Kenneth
Published: February 2008

An algorithm to determine the sensible heat flux from simple field measurements (wind speed, air and ground temperatures) has been developed. It provides a direct solution, in parametric form, which can be displayed graphically or tabularly. This method has an advantage over the previous iterative solution in that the computation is fast. It also provides a clearer understanding of the drag coefficient, its variation and response to different conditions. A simple example illustrated that at low wind speeds the drag coefficient cannot be treated as a constant. Both the computational speed and analysis of the drag coefficient can be important for remote‐sensing applications involving thermal scanner data.