bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral extinction of direct solar radiation by the El Chichon cloud during December 1982
Authors: Dutton Ellsworth , DeLuisi John
Published: February 2008

Stratospheric aerosol optical depths at five discrete solar wavelengths are calculated from solar extinction measurements made on board a NASA (National Aeronautics and Space Administration) Convair 990 aircraft between 55°N and 6°S latitude during December 1982. The latitudinal and spectral variations of the aerosol optical depths, presumed to be due to effluents from the eruptions of El Chichon, show a north to south separation into two components, each with a characteristic spectral signature. The average aerosol optical depth, both spatially and spectrally, was 0.10 ± 0.01. Calculations indicate that this enhancement is sufficient to cause an 18% decrease in direct broadband solar irradiance at a representative zenith angle of 60°.
Size‐specific composition of aerosols in the El Chichon volcanic cloud
Authors: Woods David C. , Chuan Raymond L.
Published: February 2008

A NASA U‐2 research aircraft flew sampling missions in April, May, July, November, and December 1982 aimed at obtaining in situ data in the stratospheric cloud produced from the March‐April 1982 El Chichon eruptions. Aerosol particles were sampled using a quartz crystal microbalance (QCM) cascade impactor. Post flight analyses with scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDXRA), and Auger spectroscopy provided information on the aerosol composition and morphology. The particles ranged in size from smaller than 0.05 m to larger than 20 m diameter and were quite complex in composition. In the April, May, and July samples the aerosol mass was dominated by magmatic and lithic particles larger than about 3 m. The submicron particles consisted largely of sulfuric acid. Halite particles, believed to be related to a salt dome beneath El Chichon, were collected in the stratosphere in April and May. On the July 23 flight, copper‐zinc oxide particles were collected. In July, November, and December, in addition to the volcanic ash and acid particles, carbon‐rich particles smaller than about 0.1 m aerodynamic diameter were abundant.
No water, no granites ‐ No oceans, no continents
Authors: Campbell I. H. , Taylor S. R.
Published: February 2008

Water is essential for the formation of granite and granite, in turn, is essential for the formation of continents. Earth, the only inner planet with abundant water, is the only planet with granite and continents. The Moon and the other inner planets have little or no water and no granites or continents.
Fault plane solutions for microearthquakes induced at the Fenton Hill hot dry rock Geothermal site: Implications for the state of stress near a quaternary volcanic center
Authors: Cash Dan , Homuth E. F. , Keppler Hans , Pearson Chris , Sasaki Sunji
Published: February 2008

Fault plane solutions of earthquakes induced during attempts to stimulate two hot dry rock reservoirs at Fenton Hill have significantly different patterns of first motions. The fault plane solution for the lower reservoir indicates strike slip, either left lateral strike slip on a N‐S vertical plane or right lateral slip on an E‐W vertical plane. In contrast, the solution for the upper zone includes largely vertical slip on a N‐S nearly vertical plane, or oblique slip on a nearly horizontal plane. Because the N‐S nodal plane is common in both solutions we infer that this represents the true fracture plane. Faulting thus seems to occur on a series of parallel faults or joints that intersect both reservoirs but a change in the slip vector indicates a major change in the state of stress between the upper and lower reservoirs. This latter conclusion is surprising because the two reservoirs are separated by less than 1 km. We suggest that this rapid change in the stress field may be related to the structure and subsidence of the nearby Valles Caldera.
Global distributions of cirrus clouds determined from Sage data
Authors: Woodbury Gerard E. , McCormick M. P.
Published: February 2008

An analysis using SAGE data for the period February 1979 to April 1980 was performed to determine the spatial extent and frequency of cirrus clouds over a large portion of the earth's surface. These results should be of interest to, among others, both the researchers concerned with global monitoring and modeling of the earth's radiation budget and climate and to reentry vehicle designers concerned about anomalous aerodynamic effects or damage due to the ice particles found in cirrus clouds. A by‐product of the study reveals the statistics of tropospheric observational opportunities for a limb‐sounding satellite sensor by determining the percentage of times of successful penetration to 7 km.

The results of the analysis showed that optically thick cirrus clouds are found most often in the mid‐latitudes and over the tropics with distinct minima near the ± 20 to 30° latitude bands. Thin cirrus clouds (as defined in this paper), on the other hand, occur much less often than the optically thick cirrus clouds. A comparison of the optically thick cirrus clouds observed by SAGE was made zonally with surface‐based observations and was found to generally agree. The percentage of tropospheric observational opportunities down to 7 km was as high as 60 percent in the upper latitudes but fell to about 30 percent in the tropics.
A determination of the charge state of energetic magnetospheric ions by the observation of drift echoes
Authors: Blake J. B. , Fennell J. F. , Baker D. N. , Belian R. D. , Higbie P. R.
Published: February 2008

The mean charge states of heavy ions trapped in the earth's magnetosphere are important parameters for distinguishing among magnetospheric theories. No direct measurements have been made at energies greater than ∼ 50 keV. A technique, which uses the E/q dependence of ion drift velocity, is described in this letter. A drift‐echo event, which followed a substorm that occurred at 2100‐2200 UT on 25 February 1979, is discussed to illustrate the application of this technique. In this event the charge state of helium ions was +2 and CNO ions was > +2 and probably ≥ +5. This result implies that the drift‐echo particles were from freshly injected solar‐wind plasma.
Plasma and electric field measurements of the PVO in the Venus ionosheath
Authors: Pérez‐de‐Tejada H. , Intriligator D. S. , Scarf F. L.
Published: February 2008

A study of the plasma and electric field measurements of the PVO in the Venus ionosheath near the terminator region is presented. A drastic decrease of the particle flux intensity measured with the plasma instrument is encountered in the inner ionosheath before the inbound crossing of the ionopause. The outer boundary of the region of weak plasma fluxes is consistent with the presence of a rarefaction wave as reported previously from the Mariner 5, Venera and PVO plasma measurements in the Venus wake. Near that boundary there are, in addition, appreciable changes in the electric field signals detected with the PVO electric field detector. These observations suggest the existence of local plasma wave activity associated with turbulent flow conditions in that region.
Tectonic contrasts between Venus and the Earth
Authors: Kaula William M.
Published: February 2008

The long‐wave features of the gravity field of Venus differ from those of the Earth's field not only in their strong positive correlation with topography, but also in their gentler spectral slope. These properties are inconsistent with generation of the gravity field by plate tectonics or by processes at great depths; they are consistent with generation by a mantle convective system supporting the broad features in topography with an effective compensation depth of about 450 km.
The configuration of the seismic zone and the downgoing slab in southern Peru
Authors: Grange F. , Cunningham P. , Gagnepain J. , Hatzfeld D. , Molnar P. , Ocola L. , Rodrígues A. , Roecker S. W. , Stock J. M. , Suárez G.
Published: February 2008

Using data from temporary networks of portable seismographs in southern Peru, we located 888 shallow and intermediate depth events near a proposed discontinuity in the seismic zone there. These events reveal a prominent contortion, instead of a discontinuity, that trends approximately N80°E, parallel to the direction of relative plate motion. North of about 15°S, the seismic zone beneath Peru is nearly horizontal, but south of about 15.5°S, it dips at about 25°. Volcanoes lie above the more steeply dipping zone where earthquakes occur between 120 and 140 km, and the volcanic line in southern Peru stops abruptly at the contortion.
Magnetic viscosity of some doleritic basalts in relation to the interpretation of the oceanic magnetic anomalies
Authors: Smith Brigitte M.
Published: February 2008

The growth of induced magnetization (VIM) with time t, in a .5 Oe acquisition field, followed by subsequent decrease in zero field of the viscous remanent magnetization (VRM) with time t' was investigated, at room temperature for 5 oceanic doleritic basalts, and at temperature up to 105°C for 1 dike sample. Both VIM acquisition and VRM decay are enhanced by increasing temperature and time. However, the growth and decay do not uniformly obey a log t law on an experimental time of 2 hours. The results show that, far from the ridge axes, at the bottom of oceanic pillow layer (2A) and in the upper part of the dike layer (2B) the induced magnetization might largely dominate the remanent one, while only a small fraction of the primary TRM, corresponding to the highest blocking temperatures TB, would be preserved, the partial TRM corresponding to the lowest TB having been replaced by a viscous magnetization. Consequently, the doleritic basalts would rarely, if ever, contribute to oceanic magnetic anomalies.
Magnetic properties of variably oxidized pillow basalt
Authors: Beske‐Diehl S. J. , Soroka W. L.
Published: February 2008

In our study of changes in magnetic properties during low temperature oxidation of oceanic pillows, we were able to essentially eliminate variations in grain size which plagued many previous studies. This was accomplished by keeping the cores parallel to the outer glassy margin of the pillow while drilling the variably oxidized portions of the basalt. Curie temperature (Tc) measurements indicated a large range in the degree of low temperature oxidation, although most were in the early stages of maghemitization (Tc<300°C). In samples with hysteresis parameters showing pseudo‐single domain behavior, the natural remanent magnetization (Jnrm) and susceptibility both decreased substantially with low temperature oxidation. Thus, the Koenigsberger ratio (Jnrm/Jinduced) did not change. The reduction in Jnrm was mirrored by comparable decreases in saturation magnetization and saturation remanence. Low temperature oxidation also increased the bulk coercivity and the coercivity of remanence in the oxidized basalt relative to the less oxidized. These later results are consistent with the theory that low temperature oxidation generally stabilizes the remanent magnetization of seafloor pillow basalts. The increase in coercivity with oxidation in these pillow basalts contrasts will synthetic samples which show an overall decrease. The behavior of natural samples reflects processes which occur during low temperature oxidation that do not normally occur in synthetic samples, specifically the loss of iron from the grain and perhaps grain cracking.
El Nino‐induced onshore transport in the California Current during 1982‐1983
Authors: Simpson James J.
Published: February 2008

Persistent (>9 month) large‐scale positive temperature (3‐4°C), negative salinity (0.1‐0.3‰) and positive dissolved oxygen (0.5‐1 ml/l) subsurface anomalies characterize the El Niño‐induced onshore transport in the California Current during 1982‐83. These anomalies, characteristic diagrams, and sign reversals in the salinity and oxygen anomalies are consistent only with enhanced onshore transport of Subarctic water from the offshore California Current. Onshore transport excludes poleward propagating Kelvin waves as a generation mechanism for the 1982‐83 Californian "El Niño". The data, however, support the conclusion (Simpson, 1983) that an anomalous basinwide atmospheric circulation produced the Californian "El Niño".
The evolution of large‐scale magnetic fields in the ionosphere of Venus
Authors: Cravens T. E. , Shinagawa H. , Nagy A. F.
Published: February 2008

Large‐scale magnetic fields are often observed in the ionosphere of Venus by the magnetometer on the Pioneer Venus Orbiter, especially near the subsolar point or when the solar wind dynamic pressure is high. An equation for the time evolution of the magnetic field is derived which includes both a term representing the time rate of change of the field due the convection of magnetic flux by plasma motions and a magnetic diffusion/dissipation term. The ionospheric plasma velocities required by these equations were obtained by numerically solving the momentum equation. Numerical solutions to the magnetic field equation indicate that large‐scale magnetic fields, which are not being actively maintained, decay with time scales ranging from tens of minutes to several hours. The vertical convection of magnetic flux enables magnetic field structures deep within the ionosphere to persist longer than would otherwise be expected. This vertical convection also explains the shape of these structures.
Ultraviolet imaging from space of the aurora under full sunlight
Authors: Meng C.‐I. , Huffman R. E.
Published: February 2008

This report presents the first successful global‐scale auroral images in full daylight. The vacuum ultraviolet (VUV) imager on board the recently launched HILAT satellite has demonstrated that clear images of the global auroral display over the local summer polar region under full sunlight conditions can be obtained, indicating that the earth’s albedo and dayglow background are not formidable obstacles to the global auroral imaging at the VUV wavelengths (135.6 ± 1.5 nm and 149.3 ± 1.5 nm). Some of the images of dayglow and auroras in daylight are presented and discussed.
A Paleocene North American paleomagnetic pole incorporating declination‐Only data
Authors: Gordon Richard G.
Published: February 2008

A problem in determining apparent polar wander paths for the continents is how to incorporate the valid declinations from paleomagnetic studies that have measured shallowly biased inclinations (i.e. inclination error). It is proposed that in such cases pole positions and confidence limits be determined using a method previously applied only to paleomagnetic data from oceanic plates. Applying this method to paleomagnetic data from 67‐55 Ma rocks of North America, a paleomagnetic pole, 78.7°N, 185.1°E, and 95% confidence ellipse, 6.0° major semiaxis striking 105° clockwise from north and minor semiaxis of 3.7°, were determined. An analysis of the information content of the data shows that the single declination‐only datum, from the Nacimiento Formation (New Mexico), contains 31% of the information, which would have been wasted by conventional paleomagnetic analysis if excluded or caused a bias if the inclination had also been included.
Venus: Ishtar gravity anomaly
Authors: Sjogren W. L. , Bills B. G. , Mottinger N. A.
Published: February 2008

Ishtar has been detected as a positive gravity anomaly. Verification of this result has been made with two independent data sets. Isostatic compensation of the Ishtar topography using an Airy model is achieved at approximately 150km.
Anisotropy of magnetic susceptibility: Empirical evaluation of instrumental precision
Authors: Ellwood Brooks B.
Published: February 2008

Measurement of the anisotropy of magnetic susceptibility (AMS) in rock specimens is complicated when magnitude differences between two of the three principal susceptibilities which are conventionally used in defining the susceptibility ellipsoid approach the precision limits of the instrument used. To evaluate this problem, the precision is reported for 5 replicate measurements of low field AMS in 34 samples (including diamagnetic samples) with susceptibilities ranging between 5.73 × 10−3 and 2.94 × 10−5 in mass SI units using a torsion fiber magnetometer. (These samples are available upon request for interlaboratory calibration.) Precision appears to be controlled by the within‐sample axial susceptibility ratios and not by the susceptibility magnitudes. It is observed for the instruments used in this study that when the axial ratios (χa/χc or χb /χc are equal to or less than 1.002, then the replicate precision for those axes is poor. When the axial ratios are greater than 1.005, then the precision is excellent. Such replicate AMS measurements for any given instrument provide an empirical means to determine a practical method for rejecting AMS data that are not sufficiently anisotropic for reliable measurement.
Source mechanisms of the June 7, 1982 Ometepec, Mexico Earthquake
Authors: Beroza G. , Rial J. A. , McNally K. C.
Published: February 2008

Body wave synthetic seismograms are used to study the source parameters and rupture time history of the doublet of large (M S = 6.9, 7.0) earthquakes which occurred within five hours of one another near the town of Ometepec, Mexico on June 7, 1982. The events are thrust events consistent with the subduction of the Cocos Plate beneath the North America plate. Our results indicate that these are not the simple, single source events previously thought to be typical of the Middle America Trench in this region. While the first event had a simple source time function, the second did not. This relatively complex behavior can not be explained by any tectonic complications that have been proposed to account for the complexity of the 1970 Chiapas earthquake and the 1973 Colima earthquake. Multiple earthquake sequences in 1962, 1950, and 1928 have occurred in the general area of the two 1982 Ometepec earthquakes suggesting that earthquake doublets are characteristic of this region.
A note on indirect wind speed measurements from ambient noise
Authors: Katz Eli Joel
Published: February 2008

Seven inverted echo sounders recovered in 1983 returned half hourly averages of the ambient noise at 10.25 kHz. The noise level recorded at the sounder nearest an in situ wind recorder (0°N, 28°10′W and 0°55′N, 29°20′W, respectively) is calibrated with the observed average daily wind speed. The resulting calibration curve of noise level versus observed wind speed estimates wind from noise with a standard deviation of 0.74 m s−1 for speeds greater than 3 m s−1 (The highest speeds observed were 9 m s−1. The calibration is used to estimate daily averaged wind speeds at a second sounder 1200 km to the west. The two derived wind series are coherent at periods greater than 12.7 days and in isolated frequency bands at shorter periods which correspond to known atmospheric waves. A difficulty in using these records to identify the time of the basin wide relaxation of the wind in the spring arises because of the 3 m s−1 sensitivity threshold of the ambient noise measurement.
Meanders observed in surface currents and hydrography during an Equatorial Atlantic Transect
Authors: McPhaden Michael J. , Fieux Michele , Gonella Joseph
Published: February 2008

Data collected during an equatorial Atlantic transect in June 1983 aboard the RV Marion Dufresne indicate the presence of energetic meanders of the surface South Equatorial Current with a zonal wavelength of ∼1000 km and an amplitude of 0(50 cm sec−1). Organized structures appear in the surface salinity and temperature fields as well with amplitudes of 0(1‰) and 0(1°C) respectively. These disturbances are similar to those that have been previously observed in the Atlantic and Pacific and, based on contemporaneous mooring data, are the manifestation of an unstable wave propagating westward with a period of 25 days.
Long‐range recording of vibroseis data: Simulation and experiment
Authors: Kubichek R. F. , Humphreys M. C. , Johnson R. A. , Smithson S. B.
Published: February 2008

Long‐range recording of COCORP vibrators was undertaken in the Adirondacks using a radio repeater to retransmit the vibrator start‐up code at ranges up to 100 km. A number of events were recorded at a range of 47 km; these events correspond to reflections from depths of about 9, 13, 16, 20, and 24 km and a possible Moho reflection from 40 km might be present. Simulation of VIBROSEIS recording demonstrates that low‐level signals with a S/N as low as 0.05 may be extracted from noise even though reflections have amplitudes less than the least significant bit. Such wide‐angle VIBROSEIS recording is practical and necessary in crustal reflection studies for defining the Moho and other deep reflectors.
Confidence limits on net tectonic rotation
Authors: McWilliams Michael
Published: February 2008

Estimation of confidence limits on net tectonic rotation by an ‘overlapping circles’ method can lead to values which are too large. A simple method based upon an F‐ratio test is presented which yields more accurate constraints on net rotation. An example illustrates that the limits calculated by the ‘overlapping circles’ method can be in error by more than 20%.
Strong electron heat flux modes in Jupiter's foreshock
Authors: Moses S. L. , Coroniti F. V. , Kennel C. F. , Scarf F. L.
Published: February 2008

Analysis of Voyager plasma wave data from the Jovian foreshock has revealed the existence of a new oscillation with center frequency below fp and typically lying above the upper limit Doppler shift frequency for ion acoustic waves. The properties of these waves are consistent with modes generated by a strong electron heat flux in an unmagnetized plasma. Such modes become unstable when the effective drift velocity exceeds (nCOLD/nHOT)1/2 times the thermal speed of the hot component. The occasional simultaneous appearance of more than one frequency band is a possible indication of multiple magnetic connection with the shock.
Late Paleozoic remagnetization of the Trenton Limestone
Authors: McCabe Chad , Van der Voo Rob , Ballard Martha M.
Published: February 2008

Samples of the Middle Ordovician Trenton Limestone were collected from 8 sites in Quebec, Ontario, and New York State for paleomagnetic study. Stepwise thermal demagnetization reveals a very well defined characteristic magnetization that has a corresponding paleomagnetic pole at 53.0° N, 126.9° E (K=97.7, A‐95=2.7°). This pole is not at all close to other Ordovician poles from cratonic North America but is near Late Carboniferous and Early Permian ones, indicating that the Trenton was remagnetized in the Late Paleozoic. An earlier paleomagnetic investigation of the Trenton gave a pole that did not appear to be Late Paleozoic in age. However, we demonstrate that this earlier study failed to isolate the ancient characteristic magnetization.

Rock magnetic experiments and analyses of magnetic extracts show that the carrier of magnetization is Fe3O4 that does not contain Ti or other elements in solid solution that would indicate a detrital source. The magnetite and its associated remanence appear to have a diagenetic origin.
Slow mode shocks in the Earth' magnetotail: ISEE‐3
Authors: Smith E. J. , Slavin J. A. , Tsurutani B. T. , Feldman W. C. , Bame S. J.
Published: February 2008

High time resolution magnetic field measurements adjacent to the boundary of the distant magnetotail plasma sheet have been analyzed. The nature of the changes in the field between the lobe and the plasma sheet is consistent with the boundary being a slow mode shock. The crossing times are relatively long (∼30 sec) implying a shock thickness estimated to be approximately 10³ km. An increase in the entropy of the electrons is consistent with dissipation at the shock. Reasonable shock normal directions are derived and may be used to determine the location of the spacecraft relative to the reconnection or merging region. It is suggested that a foreshock exists in which upstream wave and particle phenomena are occurring.
A comparative study of distant magnetotail structure at Venus and Earth
Authors: Slavin J. A. , Smith E. J. , Intriligator D. S.
Published: February 2008

Pioneer Venus and ISEE‐3 observations are used to conduct a comparative investigation of distant magnetotail structure at Venus and Earth. Both magnetotails are found to be well ordered out to the apoapses of PVO and ISEE‐3 which are at 11‐12 Rv and 220‐240 Re. The estimated lengths of the Venus and Earth magnetotails are 100‐150 Rv and 600‐6000 Re. Despite their very different interactions with the solar wind, the magnetotails of these two planets possess many similarities. The Venus tail appears to have distinct mantle, lobe, plasma sheet boundary layer, and plasma sheet regions much like its terrestrial analogue. It is further shown that the plasma sheet magnetic field distributions in the disant tails of Venus and Earth are consistent with disconnection from the planet. In particular, the 〈BZ〉 = −0.25 nT observed by ISEE‐3 X = −210 to −225 Re is sufficiently negative on the basis of flux conservation for the average location of the tail neutral line to always earthward of X = −210 Re. Finally the lobe field magnitudes are approximately those expected on the basis of average solar wind conditions, while the mean plasma sheet beta values inferred from pressure balance arguments are 8.5 and 3.8 for Venus and Earth, respectively.
Comparison of the Jovian north and south pole aurorae using the IUE observatory
Authors: Skinner Thomas E. , Moos H. Warren
Published: February 2008

New results on the spatial and temporal variability of the auroral emissions from Jupiter have been obtained from three IUE observations of the south pole made during the period July 1983 to March 1984. The current observations, together with previous IUE studies of the north pole aurora, provide convincing evidence for persistent longitudinal asymmetries in the Jovian auroral emissions. The strongest emissions appear to originate from regions centered near λIII ∼ 0° at the south pole and λIII ∼ 185° at the north pole. Differences in surface magnetic field strength seem inadequate to explain the extent to which particles precipitating along field lines into a given longitude sector in one hemisphere are inhibited from precipitating along the same field lines into the opposite hemisphere. Thus, the IUE auroral results present a challenge to existing models of auroral production.
Paleomagnetic results from some Permian‐Triassic rocks from southwestern China
Authors: Chan Lung S. , Wang Chi Y. , Wu Xue Yi
Published: February 2008

The Ailao Shan fault zone in West Yunnan represents a suture boundary between South China and Indosinian Cratons. Preliminary paleomagnetic results from three sites in Sichuan, Guichou, and Yunnan Provinces reveal a 14° northward migration of South China Craton between Late Permian and Middle Triassic. The two cratons were separated by about 20° latitudes during the Early Triassic. The tectonic setting of East Asia during the Triassic was probably analogous to the present Indonesian region.
Antarctic observations of stratospheric aerosol and high altitude condensation nuclei following the El Chichon eruption
Authors: Hofmann D. J. , Rosen J. M.
Published: February 2008

A balloon sounding to 32 km altitude was conducted at the U. S. station on McMurdo Sound in Antarctica in October 1983. The purpose of the sounding was twofold. First, to determine the extent to which sulfuric acid aerosol from the April 1982 eruption of the Mexican volcano El Chichon had affected the Antarctic stratospheric aerosol layer and, second, to determine if sulfuric acid condensation nuclei are produced at high altitude in the Antarctic stratosphere as had been observed in the northern hemisphere during the late winter ‐ early spring period. The results indicate that stratospheric transport to the south polar region was very effective with aerosol mixing ratios observed to be similar to those in the northern hemisphere for the same time period. Observation of relatively high concentrations of condensation nuclei at high altitude and associated temperature variations tend to support the validity of an aerosol production process proposed to explain earlier northern hemisphere results.
Comment composition of the polar wind ‐ not just H+ and He+
Authors: Gurgiolo C. , Burch J. L.
Published: February 2008

In their paper "First measurements of the supersonic polar wind", Nagai et al. (1984) make the point that, because the ion measurements presented in our earlier publication on the polar wind (Gurgiolo and Burch, 1982) were probably of oxygen, the observations were not of the polar wind but of an unspecified alternate ion upflow. The impression is given that oxygen is not considered a polar wind constituent. Allusions are also made to the energy range of our measurements indicating that it is too high to measure the polar wind. Such arguments are not consistent with the current work being done on the supersonic polar wind.
Ram vehicle glow spectrum; Implication of NO2 recombination continuum
Authors: Swenson G. R. , Mende S. B. , Clifton K. S.
Published: February 2008

An experiment was operated on several space shuttle missions to provide spatial and spectral distributions of a ram glow associated with the orbiter. The most recent data featured resolved spectrum and imagery of the glow with spectroscopic resolution of 34 Å FWHM between 4000 and 8000 Å. The spectrum of the glow on the shuttle tail pod could be clearly separated from spectrum of the reflected light from the orbiter. Analysis and comparison have been performed which strongly suggest the emission originates from recombination continuum of NO2. Both fast recombination (high temperature) and the spectral dependence in lifetime can describe the spectral difference. If the recombined NO2 retains 25% of the kinetic energy of the ram OI, the thickness of the glow layer can be explained by the lifetime of NO2 (²B1) recombination emission.
Sea level fluctuations in the Pacific during the 1982‐83 El Nino
Authors: Wyrtki Klaus
Published: February 2008

Sea level records are used to describe and discuss the response of the sea surface topography of the equatorial Pacific Ocean during the 1982‐83 El Nino event. During the second half of 1982 westerly winds over the western Pacific caused a draining of warm water from the area north of the equator and a first peak of sea level at the Galapagos Islands in December. During the first half of 1983 westerly winds to the south of the equator caused draining of warm water from the area between the Solomon Islands and the Marquesas Islands and a second peak of sea level at the Galapagos Islands in May. At the end of El Nino in October 1983 sea level over the entire equatorial Pacific was below normal, indicating a loss of warm water from the equatorial Pacific.
A time‐dependent theoretical model of the polar wind: Preliminary results
Authors: Gombosi T. I. , Cravens T. E. , Nagy A. F.
Published: February 2008

The coupled time dependent continuity, momentum and energy equations of a two ion (O+ and H+) quasineutral plasma were solved in order to extend our understanding of polar wind behavior. This numerical code allows studies of the time dependent behavior of polar wind‐type flows into and out of the ionosphere. Initial studies indicate that the typical time constants for electron and ion temperature changes are of the order of minutes and tens of minutes, respectively. The response time of the minor high altitude ion O+ is less than an hour, whereas that of the major ion, H+, is many hours. The initial test runs also demonstrate the fact that temporary supersonic flows of both O+ and H+ are possible, especially in the presence of significant ion heating.
Artificial plasma density structures produced by energetic electron beams from rockets and spacecraft
Authors: Banks P. M. , Gilchrist B. E.
Published: February 2008

Recent rocket and space shuttle experiments have demonstrated the capability to launch electron beams of moderate power (100 W to 10 kW) into the earth's ionosphere and magnetosphere. In this letter we describe how such beams, when fired from rockets or satellites, can create significant ionization in the E and F‐regions of the ionosphere. Through proper selection of beam‐related parameters, an interesting variety of plasma density structures, including plasma sheets and plasma filaments, can be created and studied over periods of 30 minutes to 1 hour, depending on the rate of plasma recombination and the density of the ambient plasma. Observations of these structures can give new information relating to the physics of plasma density structures in the ionosphere and the effects these features have upon the scattering of radio waves. It is also possible that observations of the density structures will provide a new means for studying neutral winds and electrodynamic phenomena in the ionosphere.
High time resolution plasma wave and magnetic field observations of the Jovian bow shock
Authors: Moses S. L. , Coroniti F. V. , Kennel C. F. , Scarf F. L. , Greenstadt E. W. , Kurth W. S. , Lepping R. P.
Published: February 2008

High time resolution (60 ms) Voyager magnetometer and plasma wave measurements of a strong (fast Mach number 16), quasi‐perpendicular Jovian bow shock reveal an abrupt change in the plasma wave spectrum at the leading edge of the shock foot. Upstream electron plasma waves terminate at the leading edge, and are replaced by a lower‐frequency broadband spectrum of ion‐acoustic‐like waves, which terminates at the main shock ramp. The clear association with the foot region of the lower frequency component suggests that it is generated by reflected ions. If the upstream plasma waves are generated by an escaping electron heat flux, their termination at the leading edge suggests that electrons are heated by the low‐frequency waves in the shock foot.
Response of the tropical tropopause to El Chichon and the El Nino of 1982‐1983
Authors: Gage K. S. , Reid G. C.
Published: February 2008

We present time series of anomalies of tropopause height, tropopause potential temperature and lower stratospheric potential temperature over the tropical western Pacific for the period 1980‐1982. These observations show a decrease in tropopause height as anticipated following the lower stratospheric warming associated with El Chichón. However, the magnitude of the decrease in tropopause height is considerably less than expected. Analysis reveals, however, that the tropospheric warming associated with the El Niño can account for this discrepancy.
Infrared measurements of atmospheric ethane (C2H6) from aircraft and ground‐based solar absorption spectra in the 3000 cm−1 region
Authors: Coffey M. T. , Mankin W. G. , Goldman A. , Rinsland C. P. , Harvey G. A. , Malathy Devi V. , Stokes G. M.
Published: February 2008

A number of prominent Q‐branches of the ν7 band of C2H6 have been identified near 3000 cm−1 in aircraft and ground‐based infrared solar absorption spectra. The aircraft spectra provide the column amount above 12 km at various altitudes. The column amount is strongly correlated with tropopause height and can be described by a constant mixing ratio of 0.46 ppbv in the upper troposphere and a mixing ratio scale height of 3.9 km above the tropopause. The ground‐based spectra yield a column of 9.0 × 1015 molecules cm−2 above 2.1 km; combining these results implies a tropospheric mixing ratio of approximately 0.63 ppbv.
Seismicity and volcanism in the Pacific Northwest: Evidence for the segmentation of the Juan De Fuca Plate
Authors: Weaver Craig S. , Michaelson Caryl A.
Published: February 2008

The distributions of earthquakes and late Cenozoic and Quaternary volcanism in Washington and northern Oregon change markedly across two northeast‐striking lines, one near Mount Rainier and one near Mount Hood. On the basis of these observations and a comparison with the Nazca subduction zone, we propose that the Juan de Fuca subduction zone is divided into two segments. Landward of the coastal thrust zone, we suggest the Juan de Fuca plate dips more steeply beneath the southern segment than beneath the northern segment.
Mantle contamination under Akagi Volcano, Japan, as inferred from combined Sr‐O isotope relationships
Authors: Notsu Kenji , Kita Itsuro , Yamaguchi Takashi
Published: February 2008

The Northeast Japan arc is associated with westward subduction of the Pacific plate beneath the Eurasian plate. At the southernmost region of the arc, the Philippine Sea plate subducts northward into the mantle wedge between the Eurasian plate and the Pacific slab. Akagi volcano located at this region yields volcanic rocks with combined Sr‐O isotope relationships which are explained in terms of the mixing of the mantle material from the mantle wedge and deep ocean and/or continent derived sediments conveyed with the subducting Philippine Sea plate. This implys that the Philippine Sea plate continues to the location just under Akagi volcano, although the seismic Philippine Sea plate does not reach just under the volcano.
DE‐1 measurements of AKR wave directions
Authors: Calvert W.
Published: February 2008

In addition to its wave rotation sense, the direction of auroral kilometric radiation (AKR) can also be measured with the plasma wave Instrument on Dynamics Explorer 1, from the relative phase of the signals received by its orthogonal electric dipole antennas. By this method, which differs in principle from the previous spin‐null method for measuring wave directions, it has been found possible to pinpoint the AKR source by triangulation, using measurements from different points along the DE‐1 orbit. The resulting apparent source, in one instance, seemed to occupy a well‐defined auroral‐zone invariant magnetic latitude and showed the expected increase of altitude with decreasing frequency. An analysis of the method also confirmed the validity of the previous rotation sense measurements.
Possible seasonal variability of mesospheric water vapor
Authors: Bevilacqua R. M. , Wilson William J. , Ricketts William B. , Schwartz Philip R. , Howard R. J.
Published: February 2008

We have made ground‐based spectral line measurements of the 22.2 GHz water vapor line in atmospheric emission at the Jet Propulsion Laboratory, which have been used to deduce the mesospheric water vapor profile. The measurements were made nearly continuously in the spring and early summer of 1984. The results indicate a temporal increase in the water vapor mixing ratio in the upper mesosphere from April through June. At 75 km, this increase is nearly a factor of 2. Comparison of the present results with the results of a similar series of measurements made at the Haystack (radio astronomy) Observatory indicate that this temporal increase is part of a seasonal variation.
Lattice dynamics and structural distortions of CaSiO3 and MgSiO3 perovskites
Authors: Wolf George H. , Jeanloz Raymond
Published: February 2008

The phonon spectra, distortion mechanisms, and thermoelastic properties of CaSiO3and MgSiO3 in the cubic perovskite structure are investigated as a function of pressure using a lattice dynamic approach. The bonding forces are derived from a parameter‐free rigid‐ion electron‐gas formulation. At low pressures, CaSiO3 is found to be dynamically stable in the cubic perovskite structure; however, the phonon spectrum exhibits soft modes at the Brillouin zone boundary which ultimately result in a dynamic instability of the lattice near 80 GPa. The computed phonon spectrum of cubic MgSiO3 perovskite exhibits complex frequencies along parts of the zone boundary at all densities investigated. These vibrational instabilities include coupled octahedral rotations which produce the observed distorted structure of MgSiO3 perovskite. The measured bulk modulus of MgSiO3 perovskite compares well with our calculated value for the cubic structure.
Atmospheric methanesulfonic acid and non‐sea‐salt sulfate at Fanning and American Samoa
Authors: Saltzman E. S. , Savoie D. L. , Prospero J. M. , Zika R. G.
Published: February 2008

Atmospheric concentrations of aerosol methanesulfonic acid (MSA) and non‐sea‐salt (nss) sulfate were measured in samples collected during one year periods at Fanning and American Samoa Islands in the Pacific Ocean. Mean concentrations were 0.045 (s=0.011) ug/m⊃3 MSA and 0.67 (s=0.13) ug/m⊃3 nss sulfate at Fanning, and 0.026 (s=0.012) ug/m⊃3 MSA and 0.41 (0.19) ug/m⊃3 nss sulfate at American Samoa. MSA and nss sulfate were significantly correlated at both stations (r=0.76), with a mean MSA/nss sulfate ratio of 0.065. The higher mean levels of MSA and nss sulfate at Fanning compared to American Samoa apparently reflect differences in the biological productivity of the surface ocean in the two regions.
Stratospheric CℓO: In‐situ detection with a new approach
Authors: Brune Wm. H. , Weinstock E. M. , Schwab M. J. , Stimfle R. M. , Anderson J. G.
Published: February 2008

Stratospheric chlorine monoxide concentrations were measured in situ using a new and improved observational method in which the detection package is lowered and then reeled back up. Two reel down and reel up sequences covering 38 to 31 km produced [CℓO] profiles which agree with each other to ± 12%. The measured [CℓO] profile falls within the envelope of nine previous "fast" parachute drop results, but exhibits a different shape, peaking near 32 km as opposed to ∼39 km for the average of the previous profiles. These results are consistent with the profiles derived from remote sensing methods, and indicate the need for simultaneous measurements of relevant species.
ELF wave production by an electron beam emitting rocket system and its suppression on auroral field lines: Evidence for Alfven and drift waves
Authors: Winckler J. R. , Erickson K. N. , Abe Y. , Steffen J. E. , Malcolm P. R.
Published: February 2008

ELF electric disturbances in the frequency range from DC to 1 kHz produced in the auroral ionosphere by the injection of powerful electron beams have been studied by orthogonal probes on a free‐flying plasma diagnostics payload. Frequency spectrograms have been produced for various pitch angles, pulsing characteristics and other properties of the injected beams. The large‐scale DC ionospheric convection electric field has also been measured, as well as the auroral particle precipitation, the visual auroral forms and the ionospheric parameters. The convection field was strongly attenuated as the experiment system moved northward across discrete arcs but recovered to a higher value north of the arcs where the particle precipitation ceased. The production of ELF waves by beam injection was also strongly reduced in the arcs, and like the DC field, recovered to an even greater intensity north of the arcs. This behavior did not extend into the lower hybrid or whistler mode region. The DC field decrease has been explained by the high Pederson conductivity caused by auroral electron precipitation in the E‐region below the vehicle. It is postulated that the observed ELF waves are in the Alfven and drift modes and are generated by the positive vehicle potential during beam injection. More effective vehicle neutralization in the auroral arcs lowers the vehicle potential and, therefore, reduces wave production. Most features of the experimental observations can be qualitatively explained by this mechanism.
The geomagnetic coast effect in the Pacific Northwest of North America
Authors: Neumann Gregory A. , Hermance John F.
Published: February 2008

During the summer of 1984, Brown University measured magnetic variations at a series of 9 sites along an 80 km profile which began in the Willamette Valley in West‐Central Oregon, extended westward across the Coast Range, and terminated at the coast of the Pacific Ocean. Our primary objective was to investigate the "coast effect" with a density of coverage and at shorter periods (10‐100 sec) than had previously been attempted in this region. The data collected show a significant coast effect at sites closest to the ocean. While it is tempting to assume that, to first‐order, all such effects are due to induced electric currents flowing in the ocean, our studies for the Oregon coast show that the contribution of electric currents flowing in the lithosphere, especially the contribution of induced currents in a thick accretionary wedge of marine sediments offshore, is actually more significant than the contribution from the ocean itself. In addition, we have detected a conductive feature beneath the Coast Range which appears to be another zone of structurally coherent sediments along our profile. The pattern of short‐wavelength induction anomalies inland suggests that at these periods a very close spacing of sites (5 km or less) is called for in future studies.
A strain anomaly near the southern end of the San Andreas Fault, Imperial Valley, California
Authors: Reilinger Robert
Published: February 2008

Repeated first‐order leveling surveys conducted by the National Geodetic Survey (NGS) in 1972, 1974, 1976, 1978, and 1981 provide evidence of contemporary relative uplift near the junction of the San Andreas fault and the Brawley Seismic Zone. Uplift, which extends over a distance of about 5 km where crossed by the leveling line, apparently developed progressively between 1972 (possibly before) and 1978. Maximum relative uplift during this period reached 58 ± 4 mm. This spatially and temporally coherent pattern of uplift was interrupted between 1978 and 1981 possibly as a result of the 1979, M6.6 Imperial Valley earthquake. While the cause of the observed uplift is unknown, given the location, one interpretation is that it represents a zone of concentrated strain possibly associated with fault activity.
Large amplitude thermospheric oscillations induced by an earthquake
Authors: Kelley M. C. , Livingston R. , McCready M.
Published: February 2008

Large amplitude long period vertical oscillations of the thermosphere were detected over Chatanika, Alaska, just after an earthquake. The oscillations continued for at least nine hours. The earthquake registered 5.8 on the Richter scale, and its epicenter was about 1000 km from the observing site. The vertical velocity of the atmosphere was determined via incoherent scatter measurements of the plasma velocity parallel to the earth's magnetic field, and at times exceeded 100 m/s in the 300 to 450 km height range. Analysis of the oscillation frequency and its relation to the Brunt‐Vaisala frequency yields reasonable agreement with the theory for such a process [Row, 1967], although the indicated exospheric neutral gas temperature is on the high side of expected values. There is some evidence that the upper thermosphere may have been viscously heated by the oscillations, which may explain the high temperature.
Estimation and comparison of quasilinear electron heating in the shock foot at Jupiter and Earth
Authors: Moses S. L. , Coroniti F. V. , Kennel C. F. , Scarf F. L.
Published: February 2008

We develop a simple quasilinear model to estimate the electron heating that occurs in the foot of a supercritical, quasiperpendicular shock through interactions with electrostatic waves generated by reflected ions. At earth the increase in electron thermal energy calculated using the measured wave amplitudes is negligible, while at Jupiter it is comparable with the observed temperature gain across the shock. The anisotropic quasilinear heating should destabilize whistler mode waves in the foot. These have been detected by the plasma wave instrument on Voyager with amplitudes sufficient to isotropize the electron distribution.
On the proposed triggering of Jovian radio emissions
Authors: Desch M. D. , Kaiser M. L.
Published: February 2008

Calvert [1985] has proposed that solar type III radio bursts can trigger the onset of certain Jovian hectometer wavelength emissions. We show, using the data obtained by the Voyager Planetary Radio Astronomy experiment, that this triggering hypothesis is not supported statistically. Furthermore, we question the causality of this proposed triggering because much of the Jovian hectometer emission is due to a quasi‐continuous radio source rotating, in lighthouse fashion, with Jupiter. Thus, an observed "onset" of emission is simply a function of the observer's position in local time around Jupiter.