bluuebunny/crossref_metadata_2025 huggingface dataset:
High resolution electron energy spectra in an active aurora at the onset of the magnetic storm of March 26, 1976
Authors: Edmonson D. A. , Peterson W. K. , Doering J. P. , Feldman P. D.
Published: February 2008

The spectrum of high energy precipitating auroral electrons (2‐26 keV) was measured at altitudes from 97‐175 km at the onset of the magnetic storm of 26 March 1976 by a rocket borne experiment launched from Ft. Churchill, Manitoba. The spectra show an unusual double‐peaked distribution, with maxima at 4.5 and 17 keV, that persists for the full four minutes of data acquisition. Multiple structure within the main peaks is also noted. The energies and intensities of the two peaks observed at 163 km and 0° pitch angle vary independently during a sudden brightening on the downleg of the rocket flight. Thirty spectra taken during a slow roll maneuver near apogee show that the pitch angle distribution for the two peaks in the energy spectrum is isotropic over both the precipitating and backscattered hemispheres. Spectra taken near the end of the flight show energy dependent attenuation with altitude but fluctuations in auroral intensity preclude a detailed analysis.
Ultraviolet absorption spectrum of chlorine nitrite, ClONO
Authors: Molina Luisa T. , Molina Mario J.
Published: February 2008

The near ultraviolet absorption spectrum of chlorine nitrite (ClONO) has been quantitatively investigated over the wavelength range 230‐400 nm at 231°K. An absorption maximum was observed at 290 nm with a cross section of 1.5 × 10−18 cm². The calculated lifetime against photodissociation for ClONO in the atmosphere is 2 to 3 minutes. The large photolysis rate indicates that ClONO does not play a significant role in the stratosphere as a temporary holding tank for chlorine.
Seasonal variations in apparent sea ice viscosity on the geophysical scale
Authors: Hibler W. D. , Tucker W. B.
Published: February 2008

Using available atmospheric pressure and ocean current data and estimating non‐local stress transferral through the ice cover by employing a viscous drift model in the infinite boundary limit, predicted drift rates for one Russian and two U.S. drifting stations are made over the time period May 1962 to April 1964. The viscosity values giving the best fit between observed and predicted values show a pronounced winter increase that correlates well with the ice growth rate. Physically this suggests that ice drift rates (for a given wind field) tend to decrease in winter because of increased stress transferral through the ice cover. An empirical linear relationship between viscosity and ice growth rate is derived which yields predictions in reasonable agreement with both long (yearly) and short term (monthly) observed drift rates.
Suprathermal particle observations in the nighttime ionosphere at low latitudes
Authors: Prangé Renée , Crifo Jean‐François
Published: February 2008

A rocket borne electrostatic analyzer was flown through the near equatorial ionosphere, up to L ∼ 1.3, at night, during a magnetic storm associated with spread‐F. After careful correction of the observed signal, which was highly contaminated by the U.V. night glow, it appears a field aligned, upwards directed flux of soft ions with a power law spectrum, through a restricted altitude range. A comparison with earlier results indicates that it is not inconsistent with previously published upper limits, owing to the limited spatial extent of the phenomenon.
Large‐scale eddies in the Somali Current
Authors: Düing Walter
Published: February 2008

Velocity records from a subsurface mooring in the Somali Current exhibit direction reversals during a time when the SW Monsoon is still steadily blowing. The records are interpreted in terms of large‐scale eddies which seem to be generated near the equator and propagate slowly northward along the coast of Somalia.

The Somali Current constitutes the most important branch of the complex East African Current System. It is generated by the Summer Monsoon and flows along the coast of East Africa, from the latitude of Mombasa to the island of Socotra, corresponding to a distance of about 2200 km. Translated to the path of the Gulf Stream, this corresponds to the distance between Yucatan and Cape Hatteras. Despite the fact that this current has been immensely important to seafarers for nearly 2000 years, it is one of the least explored boundary current systems in the Northern Hemisphere. In contrast to the Gulf Stream, which shows only insignificant seasonal variations, the Somali Current reverses its direction following the seasonal change of the monsoon winds. A first long‐term current meter record from the region indicates that the classical picture of a straightforward oceanic response to the forcing of the windstress may be greatly oversimplified. It is shown that some of the key features of the record are not related to fluctuations of the wind field, but more likely to large‐scale eddies propagating northward along the coast.
Deep crustal electrical conductivity; Evidence for water in the lower crust
Authors: Nekut A. , Connerney J. E. P. , Kuckes A. F.
Published: February 2008

Controlled source magnetic induction experiments in the Adirondack Precambrian shield region of northern New York State indicate that the electrical conductivity in both the upper and lower crust are in conformity with laboratory studies of moist, igneous rock and in serious discord with such measurements on dehydrated rock. A two order of magnitude increase in the conductivity found at 20 km depth suggests a structural or phase change there. A single turn loop of wire 1.5 km in diameter was used to generate an oscillating magnetic dipole source field over the frequency range 0.4 to 390 Hertz. The amplitude and phase of the resulting fields were measured as a function of distance to 90 km from the source. Analysis of these measurements indicates approximate horizontal stratification of the electrical conductivity. The uppermost layer, which is no more than a few hundred meters thick, has a conductivity thickness product of 0.4 (ohms)−1. It is underlain by a conductivity of about 8 × 10−5 (ohm meters)−1 to a depth of about 15 km. The conductivity between 15 and 20 km is approximately 10−3 (ohm meters)−1; the conductivity is greater than 10−2 (ohm meters) −1 below 20 km.
High strain rate studies in rock
Authors: Grady Dennis
Published: February 2008

Dynamic compression studies using high velocity impact are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brought to a shock compressed state. Although this is frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate of these methods makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates in the range of 104/s to 106/s for final stress states of approximately 3.9 GPa or less.

Ramp wave compression experiments have been conducted on dolomite at strain rates of 3 × 104/s. Both initial yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (⋵ ∼ 106/s) and differs substantially from quasi‐static measurements (⋵ ∼ 10−4/s). The ramp wave studies have also uncovered a pressure‐induced phase transition in dolomite initiating at 4.0 GPa.
Paleoclimate, paleomagnetism and the eccentricity of the Earth's orbit
Authors: Wollin Goesta , Ryan William B. F. , Ericson David B. , Foster John H.
Published: February 2008

Climatic changes, geomagnetic intensity fluctuations, and variations of the eccentricity of the earth's orbit during the past 0.8 m. y. are compared. In general, warm climate stages are aligned with low magnetic field intensities and high orbital eccentricity. We tentatively conclude that the eccentricity of the earth's orbit may partially modulate both the earth's magnetic field and climate.
Signatures of electric fields from high and low altitude farticles distributions
Authors: Mizera Paul F. , Fennell Joseph F.
Published: February 2008

Measurements of high altitude (<1.3 R e) ions and electrons at auroral energies are used to provide evidence of parallel electric field acceleration over the dusk to midnight auroral regions for both the north and south hemispheres. The data, taken on August 12, 1976 by charged particle spectrometers on the S3‐3 satellite, show evidence of potential differences of ∼2 kV below and ∼1 kV above a satellite altitude of 7300 km.
Measurement of magnetic field aligned potential differences using high resolution conjugate photoelectron energy spectra
Authors: Peterson W. K. , Doering J. P. , Potemra T. A. , Bostrom C. O. , Brace L. H. , Heelis R. A. , Hanson W. B.
Published: February 2008

Simultaneous high resolution observations of a distinctive feature in the energy spectrum of conjugate photoelectrons and spacecraft potential relative to the local ionosphere have allowed the net potential difference between magnetic conjugate points at latitudes below the region of low energy (E 〈 100 eV) auroral electron precipitation to be determined. Measurements made at 300 km, from Atmosphere Explorer C show that there is normally no net potential difference between hemispheres in this region which extended up to invariant latitudes as high as 74°. Two types of apparently related anomalous behavior were infrequently observed at high latitudes. During these periods the incident flux of conjugate photoelectrons was either decelerated by about 3 eV or was not detected.
Kinetics of the reaction of HO2 with NO
Authors: Howard Carleton J. , Evenson K. M.
Published: February 2008

The gas phase reaction of HO2 radicals with NO was studied using a discharge‐flow system and laser‐magnetic resonance detection. Concentrations of HO2 down to 2 × 109 molecules/cm³ were detectable, thus allowing the reaction to be studied under pseudo‐first‐order kinetic conditions. The rate constant was measured using three independent kinetic schemes, one of which involved the detection of the reaction products OH and NO2. The three schemes gave results in excellent agreement. The rate constant, k1, for the reaction

urn:x-wiley:00948276:media:grl591:grl591-math-0001
is (8.1 ± 1.5) × 10−12 cm³/molecule·s at 296K and a pressure of 140‐220 Pa (1.1‐1.7 torr). The measurements also indicate that the rate constants for two other exothermic channels of the reaction are less than 2% of k1.
Northeast Chukchi sea coastal currents
Authors: Hufford G. L.
Published: February 2008

The characteristics of the surface currents off Point Franklin, Alaska (August 1976), show a southwesterly flow inshore and offshore separated by a northeasterly flow. The offshore southwesterly flow has never been observed before. The surface current regime occurred during a period of persistent northeasterly winds (average speed = 6.9 m sec−1). However, the wind does not appear to be the major driving force of the currents except near shore. Transport calculations show that the offshore southwesterly current was the dominant flow. The drift trajectory of three RAMS buoys (winter 1975‐76) during an AIDJEX study indicates that the offshore southwesterly current can occur during other seasons.
Asthenospheric shear flow: Thermally stable or unstable?
Authors: Yuen David A. , Schubert Gerald
Published: February 2008

One‐dimensional shear flows may decouple certain lithospheric plates from the deeper mantle, especially beneath continental shields. We investigate the variety of such flows which can occur in a model upper mantle with an olivine rheology and radiogenic heat sources. The thermal stability of these states is examined. The flows are stable if the horizontal velocity at the top of the mantle is fixed. If, on the other hand, the shear stress is fixed, instability may occur due to viscous heating associated with the strong temperature dependence of the olivine rheology. The boundary condition relevant to the real earth is undoubtedly neither of these.
The HF:HCl ratio in the 14‐38 km region of the stratosphere
Authors: Farmer C. B. , Raper O. F.
Published: February 2008

Near infrared absorption spectra covering the 1‐0 bands of HF and HCℓ were recorded with a high resolution Michelson interferometer during a balloon flight near Broken Hill, Australia (30.5°S, 138.5°E) in March 1977. The ratio of the number density of HF to that of HCℓ as a function of altitude in the stratosphere was deduced from measuremnts of the Rl features of both gases. The experimental errors vary over the altitude range covered by the measurements, their estimated values being ±25% between 14 and 30 km, increasing to ±50% at the extremes of the range (14 and 38 km). Within these estimated errors the ratio is constant, its mean value being HF:HCl = 0.1.
Intense poleward‐directed electric fields near the ionospheric projection of the plasmapause
Authors: Smiddy M. , Kelley M. C. , Burke W. , Rich F. , Sagalyn R. , Shuman B. , Hays R. , Lai S.
Published: February 2008

A dc electric field experiment on the Air Force satellite S3‐2 has occasionally detected intense localized electric fields near the ionosphere projection of the plasmapause. These poleward directed electric fields were observed in the pre‐midnight local time sector, seem to be related to substorm activity, and typically exceeded 100mV/m. In one case the field was 280mV/m corresponding to a drift velocity of 9.8 km/s at an altitude of 1463 km and a potential drop of 25 kilovolts. A possible source lies in the interaction between hot plasma freshly injected near magnetic midnight and the cold plasmaspheric particles. Since the potential drop is the order of the mean ring current energy, this structure may have important consequences for the understanding of magnetospheric flow patterns under disturbed conditions.
A source of bias in multiple ScS differential travel times determined by waveform correlation
Authors: Butler Rhett
Published: February 2008

Differential travel times determined by waveform correlation techniques between seismic phase pairs suffer an inherent systematic bias with respect to conventional visual timing methods if the phase pairs have different attenuation histories. Synthetic shear waves are generated with attenuation histories appropriate for multiple ScS waves. The bias between the ScS2‐ScS differential time determined by visual onset and a differential time picked by waveform cross‐correlation ranges between 2.2 and 3.8 seconds late, for an assumed average Qβ of the mantle of 312 and 156, respectively. Corrections are calculated for the various ScSn−ScSn−1 phase pairs for a range of ScS t* values.
The Earth hydrogen exobase near a solar minimum
Authors: Vidal‐Madjar A.
Published: February 2008

Measurements of the solar Lyman alpha flux and of the exobase hydrogen density distribution were made by the University of Paris experiment aboard the Orbiting Solar Observatory (OSO‐5) during the period August 1974 to August 1975. These data were obtained near the end of the solar cycle # 20, at a time of nearly minimum solar activity. To compare most accurately solar minimum and solar maximum conditions, these data were subjected to the same analysis procedures used for OSO‐5 data from 1969‐1972 (Vidal‐Madjar et al., 1973).

The results are presented individually and the average exobase hydrogen density is observed to reach 3.5 × 105 atoms cm−3 (at 500 km) for an average exospheric temperature as low as 725 K. This result shows that the non‐thermal escape mechanism increases even more than previously observed. For low solar activity conditions, the non‐thermal escape flux can be more than a factor seven larger than the Jeans escape flux.

The non‐thermal mechanisms become increasingly important at low solar activity; the minimum‐to‐maximum density ratio deduced from only dayside measurements is also observed to increase at solar minimum and may reach values as high as 3.7, although the average value is of the order of 2.1.

Finally, the dayside, latitudinal sub‐solar bulge monitored from 1969 to 1972 is still observed at solar minimum and presents the same amplitude as during solar maximum conditions.
Comparison between wind profiles measured by Doppler radar and by rawinsonde balloons
Authors: Warnock J. M. , VanZandt T. E. , Green J. L. , Winkler R. H.
Published: February 2008

Sensitive Doppler radars can measure the Doppler spectrum of echoes from refractive index irregularities in the clear air. In this paper horizontal winds estimated from the mean Doppler shift measured by the Sunset VHF Radar, near Boulder, CO, are compared with rawinsonde winds from balloons that passed within 25 km of the radar. Below 6 km MSL some of the measurements do not agree, presumably because of orographic effects. Above 6 km MSL almost all of the measurements agree within the experimental errors with a correlation coefficient of 0.96 with 16 measurements.
A comment on the effects of man‐made VLF waves on the radiation belts
Authors: Lyons L. R. , Williams D. J.
Published: February 2008

It has recently been suggested that man‐made VLF waves may have a significant effect on the overall structure of trapped energetic electrons within the plasmasphere, including the slot region. While these suggestions are intriguing and should be studied further, we conclude on the basis of previously published results that the overall structure of energetic trapped electrons within the plasmasphere is determined by radial diffusion and interactions with plasmaspheric hiss and the atmosphere. Man‐made radiation could possibly cause local perturbations at a specific point in space and time; however, we find no evidence at this time for effects that would significantly alter the overall structure of the radiation belts.
Radar measurements of waves in the lower stratosphere
Authors: Rüster R. , Röttger J. , Woodman R. F.
Published: February 2008

Measurements have been carried out using the 50‐MHz radar facility at Jicamarca/Peru applying the spaced receiver technique for investigating dynamical processes in the lower stratosphere. Using cross‐spectrum analysis, an example of observations of significant velocity oscillations with a period of 4 minutes in the height range from 16 to 25 km is presented, which is interpreted as a propagating atmospheric gravity wave with an apparent horizontal phase speed of about 10 m s−1 and a vertical one of 200 m s−1. The observed period of about 4 minutes agrees quite well with the Väisälä‐Brunt period for that height range.
Formaldehyde in rain water and on the atmospheric aerosol
Authors: Klippel Wilfried , Warneck Peter
Published: February 2008

Measurements of formaldehyde in rain water and on the atmospheric aerosol were performed at several sampling sites in Western Europe. The results are summarized in Table 1. From the data it is concluded that aerosol contributes little to the formaldehyde observed in rain water, and that formaldehyde entering rain water is fairly uniformly distributed along the 50 degree latitude, at least in Western Europe and the Atlantic ocean.
Observations of plasma instabilities in a multiple pump ionospheric heating experiment
Authors: Showen Robert L. , Duncan L. M. , Cragin B. L.
Published: February 2008

The response of the ionospheric plasma to multiple pumps is seen in the enhancements of the incoherent scatter plasma line. Two strong HF pumps are transmitted, along with weaker sidebands. The two main pumps have a frequency separation ranging from 0 to 7 kHz. At zero frequency separation the standard decay and purely growing mode instabilities are observed. When two pumps are present, the normal decay instability usually disappears, and is replaced by strong oscillations at the pump frequencies plus features half way between pairs of pumps. These "arithmetic mean" peaks appear in most of the cases observed. The weak transmitted sidebands seem to influence greatly the observed spectra; the theory is treated in a companion paper.
Evidence for a non‐random magnetization of the Moon
Authors: Hood L. , Russell C. T. , Coleman P. J.
Published: February 2008

An approximate inversion, using a specific model, of Apollo subsatellite vector magnetometer data has provided estimates for the locations, scale sizes, and magnetization characteristics of strongly magnetized lunar crustal materials across a portion of the lunar far side. The nearly model‐independent local bulk directions of magnetization, while otherwise random, exhibit a tendency to lie in or near planes perpendicular to the present lunar spin axis. The apparent existence of such a preferred plane of magnetization must be regarded as unfavorable for proposed local, presumably random sources of large‐scale, coherent magnetization and implies that any assumed internal magnetizing dipole or external linear magnetizing field must also have been oriented mainly perpendicular to the present spin axis. The otherwise random orientations of these vectors when projected onto the equatorial plane suggests a simple explanation for the negligible lunar global dipole moment.
A test of the comet hypothesis of the Tunguska Meteor fall: Nature of the meteor "thermal" explosion paradox
Authors: Liu V. C.
Published: February 2008

The hypothesis of an impinging comet used to construct the theory of the Great Tunguska Meteor Fall of 1908 is shown to be incompatible with the apparent existence of the intense terminal explosion of the meteor. A critical examination of and proposal for the mechanism of meteor explosions are made to shed light on the "thermal" explosion paradox of the Tunguska Meteoroid. A porous meteoroid model is proposed which could dispel the above‐mentioned paradox.
Apparent vertical eddy diffusion rates in the pycnocline of the Norwegian Sea as determined from the vertical distribution of tritium
Authors: Hoffert Martin I. , Broecker W. S.
Published: February 2008

If the penetration of tritium into the pycnocline of the Norwegian Sea is assumed to be via vertical eddy diffusion, the magnitude of the diffusivity must be from 3‐5 cm²/s and the buoyancy flux must be on the order of 4‐5 cm²/s³.
Stratospheric NO and HNO3 observations in the northern hemisphere for three seasons
Authors: Loewenstein Max , Starr W. L. , Murcray D. G.
Published: February 2008

Measurements of NO, HNO3, and O3 concentrations and air temperature have been made as a function of latitude in the 18 to 21 km region of the stratosphere. The NO and O3 concentrations were measured in situ with chemiluminescence detectors; the HNO3 concentrations were deduced from HNO3 column densities obtained from measurements of the radiance in the 11.2 µm band of HNO3. From the NO and HNO3 measurements the sum NOy = NO+NO2+HNO3 is inferred. Comparisons with model predictions are made for the NO concentration measured as a function of latitude for spring, summer, and fall, and for the NOy mixing ratio at 20 and 40°N. The NO measurements generally exhibit good agreement with model predictions for low and midlatitudes but poor agreement at high latitudes. The experimental NOy mixing ratios and model predictions agree within a factor of 2‐1/2 or better at both 20 and 40°N, and show excellent agreement in NOy latitudinal dependence.
Exploratory analyses of trichlorofluoromethane (F‐11) in North Atlantic water columns
Authors: Hammer Paul M. , Hayes J. M. , Jenkins W. J. , Gagosian R. B.
Published: February 2008

Seawater samples collected at four stations in the Gulf of Maine, three on the Scotian Shelf, and at a single station in the Sargasso Sea (Sept.‐Oct., 1977) were analyzed for CCl3F‐content using a rapid gas Chromatographic technique carried out on board ship. The concentrations observed in the Gulf average 2.9 × 10−12moles/liter, corresponding to significant supersaturation with regard to the overlying atmospheric concentrations and surface temperatures. Not all the excess can be attributed to prior equilibration at the colder temperatures prevailing at higher latitudes, and it seems likely that waste disposal activities may contribute to the local excess. Lower concentrations are observed at stations on the Scotian Shelf and in the Sargasso Sea, with observed stratifications in the CCl3F concentrations being well‐correlated with previously described oceanographic features.
Measurements of the reaction rates of O++ ions with N2 and O2 at thermal energy and their ionospheric implications
Authors: Johnsen Rainer , Biondi Manfred A.
Published: February 2008

A drift‐tube mass‐spectrometer apparatus has been used to determine the rate coefficients for the loss of O++ ions by charge transfer on collisions with N2 and O2 molecules. At 300 K the respective coefficients are (1.3 ± 0.3) × 10−9 and (1.5 ± 0.3) × 10−9 cm³/sec. Even at F‐region temperatures these reactions should be fast, since the rate coefficients for reactions of this type vary only slightly with increase in temperature. However, in the recent model calculations of Breig et al, the AE measurements of the O++ altitude profiles are only reproduced if the O++ + N2 rate coefficient is assumed to be much smaller than 10−10 cm³/sec. Thus we conclude that important sources of O++ ions have been omitted from the model.
The mechanics of ringed basin formation
Authors: Melosh H. J. , McKinnon William B.
Published: February 2008

Shortly after the excavation of a large impact crater the transient cavity collapses, driven by gravity. We show that at least one concentric fault scarp forms about the crater if the strength of the target material decreases sufficiently rapidly with increasing depth. This is demonstrated by two classes of models: extrusion flow models which assume a weak layer underlying a strong layer, and plastic flow models which assume a continuous decrease of cohesion strength with depth. Both classes predict that the ratio of the radius of the scarp to the transient crater radius is between 1.2 and 2 for large craters. The surface cohesion strengths needed in the plastic collapse models are consistent with those required by previous work on the slumping of small (ca. 15km diameter) craters.
Sodium hydroxide ions in the stratosphere
Authors: Ferguson Eldon E.
Published: February 2008

Recently observed non‐proton hydrate ions observed at 37 km by Arnold, Böhringer and Henschen are interpreted as being protonated sodium hydroxide cluster ions of the form NaOH2+ (H2O)n(NaOH)m. Values of n from 0 to 4 and m from 0 to 2 allow an interpretation of all seven unidentified NPH ions reported by Arnold et al. The sodium oxide molecules believed to exist below the well‐known sodium layer around 90 km are presumed to convert to the more stable NaOH molecules below ∼ 40 km where the OH/H and HO2/H concentration ratios become very large. The very large proton affinity of NaOH (∼248 kcal mol−1) virtually assures proton transfer from the H+(H2O)n ions that are produced in the stratosphere and observed to be dominant above ∼ 40 km. The possible role of other metallic species in stratospheric ion chemistry is briefly discussed.
Low latitude atmospheric X‐rays observed by HEAO‐1
Authors: Luhmann J. G. , Rugge H. R. , Blake J. B. , Christopher L. A.
Published: February 2008

The low energy (0.15‐3 keV) proportional counter detectors of the A‐2 experiment on the x‐ray astronomy satellite HEAO‐1 have detected nighttime atmospheric emissions at the limb of the earth. Three observations of this phenomenon occurred during the first two months of operation. On two occasions, fluxes greater than the diffuse galactic background were detected when the detectors scanned the limb in the vicinity of the magnetic conjugate point of the South Atlantic Anomaly. Enhanced emissions were also observed on a single scan of the atmosphere over nothern Africa. The x‐rays are presumed to result from brems‐strahlung generated by precipitating electrons. In the case of the emissions related to the Anomaly conjugate point, it is suggested that the electrons were secondaries backscattered from the atmosphere above the Anomaly during the intensified precipitation of radiation belt particles that occurs throughout a magnetic storm recovery period. These initial observations demonstrate that the earth's atmosphere can be a significant x‐ray source at low latitudes as well as in the auroral zones, and hence that it may be practical to remotely monitor the global morphology of particle precipitation by satellite observations of terrestrial x‐rays.
Velocity structure of the southeastern Hawaiian Ridge determined by Tau inversion
Authors: Estill Robert E. , Odegard Mark E.
Published: February 2008

The Tau Inversion method has been used to invert earthquake travel times from the Hawaiian Ridge to determine velocity structure with limits. The inversion gives a velocity model showing a rapid increase in velocity from 5.9 km/sec to 7.2 km/sec between 4‐km and 7.5 ‐km depth, a monotonic increase to 7.5 km/sec near 11 km, and Moho velocity of 8.0 km/sec at 15 ‐km depth. Three prominent travel time delays, indicating heterogeneous velocity structure, are shown to correspond to the major volcanoes on Hawaii: Kilauea, Mauna Loa and Mauna Kea. Also, from the Moho depth determined by Tau Inversion, we infer that previous estimates of crustal flexure for the Hawaiian Ridge, based on deeper Moho depths (> 15 km), are too large. The Tau method is shown to be useful in delineating heterogeneous velocity structure and determining limits on velocity depth models from local earthquake travel time data.
Radio aurora dynamics as seen by Doppler radar
Authors: Keys J. G. , Johnston P. V.
Published: February 2008

The data from a new doppler auroral radar system operating in the south of New Zealand reveal a number of dramatic features in the temporal and spatial distribution of the radio aurora. Data presentation is such that quantitative measurements can be made while still allowing the recognition of broad‐scale dynamic features in both echo amplitude and doppler shift.
COS in the stratosphere
Authors: Inn E. C. Y. , Vedder J. F. , Tyson B. J. , O'Hara D.
Published: February 2008

Carbonyl sulfide (COS) has been detected in the stratosphere, and mixing ratio measurements are reported for altitudes of 15.2 to 31.2 km. A large volume, cryogenic sampling system mounted on board a U‐2 aircraft has been used for lower stratosphere measurements and a balloon platform for measurement at 31.2 km. These observations and measurements strongly support the concept that stratospheric COS is an important precursor in the formation of sulfuric acid aerosols.
Current convective instability in the diffuse aurora
Authors: Ossakow S. L. , Chaturvedi P. K.
Published: February 2008

A stable E × B gradient drift geometry can become destabilized by a current along the magnetic field. This type of instability is generically called the current convective instability. This instability may be responsible for the diffuse auroral scintillation causing F region irregularities observed by the DNA Wideband satellite. In these phenomena the northward TEC gradient dominates the altitude electron density gradient. We have investigated a simple plasma fluid model and found that instability results for −k · Vd > k · (cEo/Bo) (νi/Ωi) where Vd is the relative drift (precipitation current) between ions and electrons along Bo, Eo is the westward ambient electric field (⊥Bo), and νi and Ωi are the F region ion‐neutral collision frequency and ion gyrofrequency.
On the configuration of the nightside Venus ionopause
Authors: Brace L. H. , Taylor H. A. , Cloutier P. A. , Daniell R. E. , Nagy A. F.
Published: February 2008

Nightside measurements of electron and ion concentrations by instruments on the Pioneer Venus Orbiter have revealed an ionopause that is highly dynamic and whose global configuration is unexpectedly complex. Inbound crossings which occur at high northern latitudes encounter the ionopause at an average altitude of 870 km in the late afternoon sector. The average ionopause altitude increases slightly near 110° solar zenith angle, SZA, followed by a nightside compression to well below 500 km. The outbound crossings of the ionopause occur about 20° south of the equator. The ionopause at this latitude is found at an average altitude of 800 km in the afternoon‐evening sector between 65° and 110° SZA, followed by a pronounced rise to altitudes as high as 3000 km in a pronounced bulge near 130° SZA. A gradual decrease in average ionopause height occurs between 130° and 150° SZA with the lowest ionopause heights observed beyond 150°. Superposed on this average behavior is an orbit to orbit variability of height by a factor of two or more. The difference in ionopause height at high and low latitudes near the terminator appears to confirm the asymmetry of the obstacle and shock surface observed by the Venera spacecraft and earlier predicted on the basis of theoretical arguments. The post‐terminator bulge of the ionopause at the equator and its extreme inward movement on the nightside are qualitatively consistent with the same type of theoretical arguments but require in addition the existence of strong electric fields that penetrate to very low altitudes in the cavity behind Venus.
Radon enhancements in the Earth: Evidence for intermittent upflows?
Authors: Fleischer Robert L. , Mogro‐Campero Antonio
Published: February 2008

222Rn measurements at 60cm in the earth show background patterns that can be remarkably reproducible over time. At a site in New Mexico the readings taken at monthly intervals over a 13‐month period for a set of 55 positions give different, but nearly constant monthly readings at each position, the typical standard deviation being 22%. Superimposed on that stable pattern have been three periods during which spatially grouped radon readings, increased by a factor of 2 or more over their normal values. The simplest description of the source of the increases is sporadic puffs of upflowing gas, originating at as yet unknown depths. Alternative, less likely interpretations are considered. Separate periods of mostly low radon values may be due to downflow of gas.
Martian seismicity
Authors: Goins Neal R. , Lazarewicz Andrew R.
Published: February 2008

During the Viking mission to Mars, the seismometer on Lander II collected approximately 0.24 Earth years of observational data, excluding periods of time dominated by wind‐induced Lander vibration. The “quiet‐time” data set contains no confirmed seismic events. A proper assessment of the significance of this fact requires quantitative estimates of the expected detection rate of the Viking seismometer. The first step is to calculate the minimum magnitude event detectable at a given distance, including the effects of geometric spreading, anelastic attenuation, seismic signal duration, seismometer frequency response, and possible poor ground coupling. Assuming various numerical quantities and a Martian seismic activity comparable to that of intraplate earthquakes, the appropriate integral gives an expected annual detection rate of 10 events, nearly all of which are local. Thus only two to three events would be expected in the observational period presently on hand and the lack of observed events is not in gross contradiction to reasonable expectations. Given the same assumptions, a seismometer 20 times more sensitive than the present instrument would be expected to detect about 120 events annually.
Aerosol and ice nuclei measurements in the plume of the Homer City, PA., power plant
Authors: Pueschel R. F. , Schnell R. C. , Weickmann H. K. , Wellman D. L.
Published: February 2008

The power plant produces aerosols that, in a clean atmosphere, enhance the concentration of particles of sizes smaller than 0.1 µm by more than two orders of magnitude, and of sizes larger than 1.0 µm by about a factor of ten. After two days of stagnant atmospheric conditions, ambient aerosol concentrations reach plume proportions. The plume‐related aerosol has no effect on the threshold temperature of the freezing of supercooled water.
Unusual arrival times of scatter free particles in solar proton event of May 7, 1978
Authors: Kohno Tsuyoshi , Wada Masami
Published: February 2008

Three typical scatter free arrivals of solar protons were observed by the Space Environment Monitor (SEM) on board the Geostationary Meteorological Satellite (GMS), Japanese weather satellite, during the period February ‐ October, 1978. An unusual energy dependence of arrival times is seen in one of them. Although a conclusive interpretation is not yet obtained, we report the observational results together with tentative explanations.
Propagation of a Forbush decrease in cosmic ray intensity to 15.9 AU
Authors: Van Allen J. A.
Published: February 2008

By observation of the large Forbush decrease in cosmic ray intensity of April–May 1978 at heliocentric radial distances of 1.01, 6.97, and 15.91 AU, it is found that the causative magnetized plasma cloud moved outwards from the sun at an apparent radial speed of about 960 km s−1, independent of radial distance over this range. Recovery from the impulsive decrease in intensity was markedly slower at the larger distances. On the basis of this fact and other considerations, several tentative suggestions are made as to the large scale nature of Forbush decreases and their relationship to the 11‐year solar modulation of galactic cosmic ray intensity.
A great red spot dependence on solar activity?
Authors: Schatten Kenneth H.
Published: February 2008

A new inquiry has been made into the question of whether Jupiter's Great Red Spot shows a solar activity dependence. From 1892 to 1947 a clear correlation was present. A dearth of sightings in the seventeenth century, along with the Maunder Minimum, further supports the relation. An anticorrelation, however, from 1948 to 1967 removed support for such an effect. The old observations have been reexamined and recent observations have also been studied. The author reexamines this difficult question and suggests a possible physical mechanism for a Sun‐Jovian weather relation. Prinn and Lewis' conversion reaction of Phosphine gas to triclinic red phosphorous crystals is a reaction dependent upon solar UV radiation. It may explain the dependence found, as well as the striking appearance of the Great Red Spot in the UV.
The effect of horizontal transport on auroral no densities
Authors: Roble R. G. , Gary J. M.
Published: February 2008

A time‐dependent two‐dimensional numerical model of the minor neutral constituents in the thermosphere is used to examine the effects of winds in altering the local distribution of NO produced in the aurora. The calculations show that thermospheric winds flowing through regions of enhanced local auroral production produce a “plume” of enhanced NO densities downwind from the aurora. The maximum NO densities calculated with and without horizontal winds differ by a factor of 2.6 for the case consideredindicating the importance of horizontal transport in controlling NO densities within the auroral zone.
Simulated northern hemisphere temperature departures 1579‐1880
Authors: Groveman Brian S. , Landsberg Helmut E.
Published: February 2008

Using a short‐cut method to estimate Northern Hemisphere temperature and a calibration period from 1881‐1975a number of long instrumental temperature series and some time series of proxy data were used to reconstruct approximate annual temperature departures from the 1881‐1975 average for the interval 1579‐1880.
Ionization frequencies for major thermospheric constituents as a function of solar cycle 21
Authors: Torr Marsha R. , Torr D. G. , Ong R. A. , Hinteregger H. E.
Published: February 2008

Increases in the solar ultraviolet flux (λ < 1250Å) over the past five years of rising solar activity have been larger than anticipated. This increase in UV flux dramatically affects the production of ionization of the various constituents in the thermosphere. In this paper we use measurements of the solar UV flux by the Atmosphere Explorer satellites to determine ionization frequencies for the major thermospheric species for various dates exhibiting notably different levels of solar activity. For the convenience of users of such dataa reduced set of cross section and flux data is presented for the wavelength range below 1027Åcomprising 37 wavelength intervals.
On the possible roles of gaseous sulfur and sulfanes in the atmosphere of Venus
Authors: Prinn Ronald G.
Published: February 2008

We discuss the possible importance of gaseous elemental sulfur (particularly S2S3 (thiozone) and S4) and sulfanes (H2Sn) in the lower atmosphere of Venus. These species absorb visible and near ultraviolet light. They can provide a local heating source which could drive convection in the 10‐40 km altitude region and may also contribute to the ultraviolet markings on the planet. Photodissociation of these species will result in non‐equilibrium concentrations of S and SH. This drives the lower atmosphere away from the thermochemical equilibrium species: COSH2Sand Sn and toward SO2 and possibly H2Sn. Some H2O is also converted to O2. We also discuss exothermic reactions which can provide local heating and light on the night‐side.
Methane and hydrogen in East Pacific Rise hydrothermal fluids
Authors: Welhan J. A. , Craig H.
Published: February 2008

Recently discovered hydrothermal vents at 21°N on the East Pacific Rise are discharging turbid waters at up to 400°C; mixtures of the plumes with ambient seawater contain significant amounts of dissolved H2 and CH4as well as He. The first grab samples of these waters were diluted 50‐100 foldbut they contained as much as 20 × 10−5 cc(STP) of H2 and 2 × 10−5 cc(STP) of CH4 per gram of water. H2/CH4 ratios in the vents increase with temperaturea result that is tentatively attributed to chemical equilibrium and/or the redox state of the individual waters. The phase diagram for the NaCl‐H2O "surrogate‐seawater" system shows that liquid‐vapor separation may take place prior to dischargeand mixing of a vapor phase with entrained cooler sea‐water would profoundly alter original concentrations of volatiles as well as dissolved salts. H2 and CH4 ratios to basalt‐derived helium are respectively about 550 and 70 in these waters. The total fluxes from the world‐ocean ridge systemestimated from the He‐3 fluxare of the order of 1.3 × 109 m³/y for H2 and 1.6 × 108 m³/y for CH4. The CH4 flux so calculated is sufficient to replace the deep‐sea methane in ∼ 30 yearsimplying a very rapid bacterial consumption rate below the thermocline.
Petrogenesis of Luna 16 aluminous Mare basalts
Authors: Ma M.‐S. , Schmitt R. A. , Nielsen R. L. , Taylor G. J. , Warner R. D. , Keil K.
Published: February 2008

Bulk compositionspetrology and mineralogy of > 0.5 mm Luna 16 aluminous mare basalt particles are described. The data rule out any close genetic relationships between Luna 16 and other major types of lunar mare basalts. Compared to high‐Ti mare basaltsthe Luna 16 basalts contain lower TiO2 (5.1 wt %) and Ta (∼ 0.8 ppm) and higher Al2O3 (13.3 wt %) and REE (∼ 30‐70X chondrites) abundancessuggesting that the Luna 16 source rocks crystallized later than (i.e. stratigraphically above) the ilmenite‐bearing high‐Ti basalt cumulate source rocks. The REE pattern for the Luna 16 basalts requires that the source material from which they were derived crystallized from a light REE enriched magma.
Vertical profiles of CO & CH4 in the lower and middle troposphere over the eastern United States January 1978
Authors: Reichle H. G. , Condon E. P.
Published: February 2008

Samples of tropospheric air were obtained over the Eastern United States during January of 1978. These samples were analyzed by means of gas chromatography using flame ionization detection to produce vertical profiles of carbon monoxide and methane from the surface to 8 km. The carbon monoxide mixing ratios at 35°N and 45°N agree with previously published values; however, the mixing ratio at 25°N was significantly lower than most previously published values. The methane mixing ratio was found to be weakly dependent on latitude and to have an average value of 1.64 ppm.
Ultraviolet absorption spectrum of methylhydroperoxide vapor
Authors: Molina M. J. , Arguello G.
Published: February 2008

The ultraviolet absorption cross sections of methylhydroperoxide, CH3OOH, have been measured over the wavelength range 210 nm to 350 nm at 294 K. We conclude that solar photolysis is a dominant sink for tropospheric CH3OOH. For midlatitudes the photodissociation rate is estimated to be ∼4.3 × 10−6 s−1 for 0°, 3.7 × 10−6 s−1 for 30°, and 1.0 × 10−6 s−1 for 70° zenith angle.
Detection of NO3 in the polluted troposphere by differential optical absorption
Authors: Platt Ulrich , Perner Dieter , Winer Arthur M. , Harris Geoffrey W. , Pitts James N.
Published: February 2008

The nitrate radical, NO3, has been identified and measured for the first time in the polluted troposphere using long path (970 and 750 m) differential optical absorption spectroscopy at two sites in the Los Angeles basin. NO3 concentrations of up to 355 ppt were measured using the strong NO3 absorption bands at 623 and 662 nm. During pollution episodes from September 11 to September 19, 1979 concentrations increased sharply after sunset and peaked about one hour later at ∼ 20:00 (PDT). In many other cases peak concentrations were much lower and sometimes below the detection limit of several ppt. Possible sinks for the NO3 radical under polluted conditions are considered, including reaction with NO, reaction with organic species, and the hydrolysis of N2O5 for which a new upper limit rate constant is derived.
A first report on the Petatlan, Guerrero, Mexico Earthquake of 14 March 1979
Authors: Meyer R. P. , Pennington W. D. , Powell L. A. , Unger W. L. , Guzmán M. , Havskov J. , Singh S. K. , Valdés C. , Yamamoto J.
Published: February 2008

A major earthquake, Ms = 7.6, occurred off the southern coast of Mexico near the town of Petatlan on 14 March 1979. Data recorded just before, during, and just after the event (a subset of a large data set extending from six weeks before to four weeks after the event) by local recorders including wide‐dynamic‐range instruments indicates that the earthquake ruptured a 50‐km‐long segment of the Middle American subduction zone, closely filling a seismic gap which was last ruptured by a major earthquake (Ms = 7.5) in 1943. Since recurrence times for large events in this general area are highly variable, the area remains one of high seismic risk, and provides a focus for continuing investigation of the segmentation in the subduction process which is implied by the seismic gap hypothesis.
The mechanism of ice splinter production during riming
Authors: Mossop S. C.
Published: February 2008

When an ice particle grows at about −5°C by sweeping up supercooled water drops in a cloud having a wide range of drop sizes, secondary ice particles are ejected as the drops freeze. In this way the concentration of ice particles in the cloud may increase rapidly. Present experiments show that this "splinter" formation can be considerably reduced by injecting small quantities of ammonia into the cloud. This supports the theory that splintering is a consequence of the formation of a strong ice shell round the periphery of a freezing drop. As the drop freezes the pressure within the shell increases until it is relieved by cracking of the shell. In extreme cases fragments of ice may be ejected. The addition of ammonia is thought to weaken the ice structure, thus allowing pressure to be relieved by deformation or cracking without ejection of splinters. This interpretation is supported by experiments on the freezing of larger drops "doped" with NH3 or HCℓ.