bluuebunny/crossref_metadata_2025 huggingface dataset:
The absolute concentration of O(³P) in the Earth's stratosphere
Authors: Anderson J. G.
Published: February 2008

A new technique for observing directly the absolute concentration of atoms and radicals in the earth's upper atmosphere is discussed. Atomic resonance fluorescence in conjunction with a parachute borne flow‐through module deployed from a balloon at 40 kilometers is used to determine the ground state (³P) atomic oxygen concentration between 40 and 25 kilometers in the earth's atmosphere. Under daytime equilibrium conditions: 25 November 1974; 32°N latitude; solar zenith angle 56°, 10:30AM C.S.T., the absolute concentration of O(³P) is found to decrease from 1 × 109 cm−3 at 39 km to 6 × 107 cm−3 at 26 kilometers with statistically significant local structure evident in the altitude profile.
Stratospheric Aitken particles near the tropopause
Authors: Cadle R. D. , Langer Gerhard
Published: February 2008

Concentrations of particles having radii <0.1 µm (Aitken particles) in the stratosphere immediately above the tropopause were measured with a condensation nucleus counter during horizontal flights of a jet aircraft. Order‐of‐magnitude variations in the concentrations were observed which may have resulted from the interaction of gravity waves with strata of the particles. Since the concentrations of Aitken particles are usually an order of magnitude or more smaller than those of ions in the stratosphere, it is likely that at most only a small fraction of such ions play an important role in the production of stratospheric particles.
He 584 Å airglow emission from Venus: Mariner 10 observations
Authors: Kumar Shailendra , Broadfoot A. Lyle
Published: February 2008

Observations were made across the bright limb of Venus by the ultraviolet spectrometer on Mariner 10 as the spacecraft flew by this planet on February 5, 1974. The altitude variation of the brightness of 584 Å emission is interpreted with respect to the helium distribution in the atmosphere. Resonance scattering of solar radiation is considered as the source of this emission. The comparison of model calculations with the data shows that the observed altitude profile is consistent with a He density of 2 ± 1 × 106 cm−3 at 145 km altitude (mixing ratio 1.0 ± .5 × 10−5) and with an exospheric temperature of 375 ± 105K. If the major loss of helium is by solar wind scavenging only, the present helium content on Venus can be maintained by an outgassing rate of about 2 × 105 cm−2 sec−1 from the planet crust. By using these neutral helium measurements we find that the He+ ion density in the outer ionosphere (Z > 250 km) would be ∼200 cm−3.
Measurements of stratospheric CFCl3, CF2Cl2, and N2O
Authors: Schmeltekopf A. L. , Goldan P. D. , Henderson W. R. , Harrop W. J. , Thompson T. L. , Fehsenfeld F. C. , Schiff H. I. , Crutzen P. J. , Isaksen I. S. A. , Ferguson E. E.
Published: February 2008

Stratospheric air samples have been obtained at 17.7, 22.3, and 26.2 km using balloon borne sampling spheres launched from Laramie, Wyo. These samples have been analyzed for CFCl3, CF2Cl2 and N2O, using electron capture detector gas chromatography. The concentrations of all three constituents are compared with theoretical models and found to be in excellent agreement. The dissociation products of N2O, CFCl3, and CF2Cl2 (NO and chlorine atoms) catalytically destroy ozone in the stratosphere. A knowledge of the concentrations of these species in the stratosphere is therefore essential to an understanding of the ozone balance.
Application of synchronous meteorological satellite data to the study of time dependent sea surface temperature changes along the boundary of the Gulf Stream
Authors: Legeckis R.
Published: February 2008

Thermal infrared imagery from the Synchronous Meteorological Satellite (SMS), located above the equator at 75°W, was used to produce a time‐lapse film of the Gulf Stream off Florida. Northward propagating cyclonic eddies with a speed of 39 cm/sec, spacial scale of 265 km, and low frequency (ω/f <0.15), where ω is a wave frequency and f is the Coriolis parameter, were detected at the inshore edge of the current's boundary. These results demonstrate an application of the SMS to the study of time dependent sea surface thermal patterns.
Rocket observation of electron density irregularities in the middle latitude E region
Authors: Itoh T. , Nakamura M. , Nakamura Y.
Published: February 2008

Electron density irregularity in the scale size of 4 to 100 m was observed in altitude between 90 and 120 km from rocket measurements over Japan. Analysis of the data makes clear that the spectral index of irregularities is 2 to 4 and that the irregularity amplitude is smaller than 5%. Strong irregularities exist at 92 to 95 km. The generation mechanism of these irregularities is explained by the theories of the cross field instability or the neutral turbulence.
Airborne measurements of gases and aerosols from volcanic vents on Mt. Baker
Authors: Radke L. F. , Hobbs P. V. , Stith J. L.
Published: February 2008

Airborne measurements of gases and aerosols from the recently activated volcanic vents on Mt. Baker were made on March 27 and June 30, 1975. The total rates of emission of gaseous sulfur on these two days were estimated to be 0.35 and 1.3 kg s−1, respectively. The latter rate is comparable to the largest single, industrial source of sulfur in the Pacific Northwest. A significant increase in the emission of sub‐micron aerosols was also observed between March 27 and June 30. Small aerosol particles are produced in the plume of effluents, probably by gas‐to‐particle conversion, at a rate of about 2 × 1017 s−1. However, the concentrations of cloud condensation nuclei and ice nuclei in the plume are comparatively small. Aerosols in the plume, greater than about 1 µm in diameter, consist predominantly of Al, Si, S, K and Ca. Some of the aerosols which were collected in the plume on June 30 might have been Pele'S hairs, which are a sign of new magmatic activity.
On the reaction of N+ ions with O2
Authors: Huntress W. T. , Anicich V. G.
Published: February 2008

The product distribution for the reaction of thermal energy N+ ions with O2 has been measured by ion cyclotron resonance methods. Three product channels are identified with the following fractional distribution: O2+ + N, 0.65 ± 0.04; NO+ + O, 0.31 ± 0.04; O+ + NO, 0.04 ± 0.02.
Atmospheric formation of NO from N2(A³Σ)
Authors: Swider William
Published: February 2008

The reaction between N2(A³Σ) and O(³P) contributes to the production of O(¹S) in auroras. It is argued here that the other possible products for the reaction, NO(X²π) + N(²D,4S) also may be significant and have an important impact upon odd nitrogen chemistry in the auroral E‐region and perhaps even the quiet daytime E‐region which is formed in part by ionization created by energetic electrons liberated by the absorption of solar X‐rays. The reaction between N2(A³Σ) and O2(X³Σ), which has been suggested as leading to N2O formation, is discussed.
Rocket‐borne wave, field, and plasma observations in unstable polar cap E‐region
Authors: Olesen J. K. , Primdahl F. , Spangslev F. , Ungstrup E. , Bahnsen  , Fahleson U. , Fälthammar C.‐G. , Pedersen A.
Published: February 2008

This paper presents initial results from the first comprehensively instrumented rocket flown through a Farley‐unstable polar cap E‐region. Groundbased ionosondes and magnetometers at two locations and HF radar backscatter at the launch site were used to determine the presence of a geographically widespread ionospheric plasma instability. The observed wave direction, electric field, and current density fit the predictions of the linear theory of the Farley instability, whereas the gradient‐drift instability seems to be excluded by the geometry of the observations.
Molecular oxygen measurements at 200 km from AE‐D near winter solstice, 1975
Authors: Kayser D. C. , Potter W. E.
Published: February 2008

Utilizing the fly‐through mode, the open source neutral mass spectrometer on Atmosphere Explorer‐D (AE‐D) has measured O2 densities, as well as N2 densities and in situ neutral temperatures, at midmorning during winter solstice over the latitude range 90° S to 90° N. We find the expected seasonal variation in N2 at 200 km but a more complex behavior in molecular oxygen than might be expected from a diffusive equilibrium model with constant lower boundary values. Under geomagnetically quiet conditions the equatorial 200 km value of [O2] was about 1.7 × 108 cm−3. At 120 km and equatorial latitudes a value of [O2] of ∼ 5 × 1010 cm−3 is calculated if [N2] there is 3.1 × 1011 cm−3. A somewhat higher value would be calculated if O2 is not in diffusive equilibrium above 120 km. A local maximum in the 200 km O2 densities was found near 70° N, where an average quiet time value was 2.5 × 108 cm−3, implying a 120 km density of 8.3 × 1010 cm−3. The in situ temperature measurements confirm the presence of higher temperatures near 70° N latitude, even during geomagnetically quiet conditions.
On the form and stability of open hydraulic fractures in the Earth's crust
Authors: Pollard David D.
Published: February 2008

The cross‐sectional form and stability of large hydraulic fractures are found to be very sensitive to symmetric gradients in fluid pressure and regional stress. Horizontal sections through vertical fractures may be subjected to symmetric pressure gradients by locating inflow and outflow wells near the fracture center and tips. A dumbbell form, resulting from flow from the tips toward the center, has a limital length beyond which the fracture closes at the center and propagates unstably at the tips. A diamond form, resulting from the opposite sense of flow, has no limital length and a stable propagation. These features of fracture form and stability may play an important role in the design of hydraulic fractures for geothermal energy production.
N 2 O analysis in the atmosphere via electron capture‐gas chromatography
Authors: Rasmussen R. A. , Krasnec J. , Pierotti D.
Published: February 2008

Direct measurements of ambient levels of N 2 O are possible using a hot electron capture detector. The method is very precise with a standard error of less than 1% obtained for automated analysis of ambient air samples. The system is applicable to unattended automated field studies as well as discrete laboratory analyses and/or intensive calibration studies. The system described has been used extensively in the field from mobile laboratories and on board Oceanographic research vessels.
Arecibo Middle Atmosphere Experiment
Authors: Aso T. , Kato S. , Harper R. M.
Published: February 2008

An experiment was performed using the powerful radar at Arecibo (18°N 67°E, 51° dip) to look for stratospheric and mesospheric echoes in the UHF frequency band. Strong echoes were returned from the stratospheric region, whereas no distinct returns were obtained from mesospheric heights. These results, when compared to those reported for the VHF radar at Jicamarca, support wavenumber dependences of the scattering mechanisms, such that scattering due to neutral air turbulence should be more effective at UHF frequencies than at VHF in the stratosphere, while the reverse should be true in the mesosphere. The results suggest the feasibility of utilizing the present UHF incoherent scatter radar for remote sensing of winds in the stratosphere.
Auroral patches in the vicinity of the plasmapause
Authors: Moshupi M. C. , Cogger L. L. , Wallis D. D. , Murphree J. S. , Anger C. D.
Published: February 2008

Unusual aurora‐like patches have been observed equatorward of the diffuse auroral boundary by the ISIS‐2 scanning auroral photometer. These rare features are observed predominantly in the evening sector and appear to corotate with the earth and to have lifetimes longer than two hours. Their occurrence coincides with positive going changes in the horizontal component of the earth's magnetic field (Dst). The patches are evidently excited mainly by electrons of energy somewhat higher than that of particles precipitating into the diffuse aurora (as evidenced by the lower average I(5577Å)/I(3914Å) ratio and the weakness of the red line (6300Å) emission). While intensities in the patches fall in the same range as in the "normal" auroras pole‐ward, total input power in a typical patch (108 watts) is a small fraction (.1%) of that in the auroral oval due to the different areas involved. The position of the patches leads to the conclusion that the particles creating them originate near the plasmapause.
The absence of oxide mixture in high‐pressure phases of Mg‐silicates
Authors: Ito Eiji
Published: February 2008

High pressure phase relations of MgSiO3 and Mg2SiO4 have been studied up to pressures higher than 300 kbar, using a double‐stage split‐sphere apparatus. It has been confirmed that the ilmenite phase of MgSiO3 and γ‐Mg2SiO4 transform directly at about 300 kbar to the orthorhombic perovskite phase and the assemblage of MgSiO3 perovskite plus MgO periclase, respectively. These results are consistent with those by Liu [1976 a and b] but do not support the stability of oxide mixture (periclase plus stishovite) claimed by Kumazawa et al. [1974] and Ming and Bassett [1975 a and b].
Apollo‐Soyuz O(³P) and N(4S) density measurement by UV spectroscopy
Authors: Donahue T. M. , Anderson J. G. , Rawlins W. T. , Kaufman F. , Hudson R. D.
Published: February 2008

The densities of O(³P) and N(4S) at 225 km were determined during the Apollo‐Soyuz Test Project by a resonance absorption‐fluorescence technique in which OI and NI line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of ± 15° with respect to the normal to the orbital velocity vector was scanned. The measurements described here were made at night, July 19, 1975, on two consecutive orbits at spacecraft separations of 150 and 500 m. The results indicate [O] = 1.15 × 109cm−3 ± 30% agreeing with mass spectrometric measurements made under similar conditions, and 5.6 × 106cm−3 ≤ [N] ≤ 11.2 × 106cm−3, in good agreement with recent measurements but suggesting a smaller diurnal variation than predicted by present models.
‘Hard’ viscous remanent magnetization (VRM) in fine‐grained hematite
Authors: Dunlop David J. , Stirling J. Mark
Published: February 2008

Viscous remanent magnetization (VRM) generated during the Brunhes epoch is a major source of paleomagnetic noise. VRM is usually ‘soft’ or easily erased by alternating field (af) demagnetization, but we find that in a few hour's exposure to a weak field, hematite grains 0.1−5 µm in size acquire significant VRM, about 10% of which survives af demagnetization to 400 Oe. The finer the grains and the longer the exposure time, the more intense and resistant to demagnetization VRM. Calculations using the Néel [1949] single‐domain theory of VRM indicate that ‘hard’ VRM is not confined to hematite. It is a property of fine grains of any highly coercive magnetic mineral, e.g., elongated single‐domain grains of iron in lunar rocks. In terrestrial hematite‐bearing rocks, e.g., red beds, VRM acquired over the Brunhes epoch is probably largely unaffected by routine af demagnetization. However, these rocks can be successfully cleaned by heating because ‘hard’ VRM is ‘soft’ to thermal demagnetization.
Microstructure of a magnetotail fireball
Authors: Coroniti F. V. , Scarf F. L. , Frank L. A. , Lepping R. P.
Published: February 2008

We use high time resolution data from the magnetometer, LEPEDEA and plasma wave analyzer on IMP‐7 to examine the microstructure of a long‐duration magnetotail fireball event observed during an extended quiet period on November 9, 1972. We demonstrate that the magnetic field is turbulent with fluctuation time scales down to several seconds. These findings suggest that the magnetic merging process may be a highly turbulent one, possibly associated with a form of the tearing mode instability.
Earthquakes, weather and wobble
Authors: Wilson Clark R. , Haubrich Richard A.
Published: February 2008

Two recently published reports propose different causes for the Chandler wobble excitation. One study suggests that earthquakes are important, while another investigation by us favors meteorological sources. Upon re‐examination of the earthquake data, we find that the magnitude of the estimated earthquake contribution could explain about 25% of the Chandler wobble variance, but that there is no supporting evidence of correlation with observed polar motion. We conclude that there is presently no reason to believe the earthquake portion of the Chandler wobble excitation is any larger than 25%. On the other hand, the contribution of meteorological variation appears to be not less than 25%, and may easily be much more.
Laboratory simulation of the lunar magnetosphere
Authors: Dubinin E. M. , Podgorny I. M. , Potanin Yu. M. , Sonett C. P.
Published: February 2008

The magnetic field disturbance created by the impingement of a supermagnetosonic collision‐free plasma upon a hollow, electrically nonconducting body (lunella) has been studied in the laboratory using a plasma accelerator. Diamagnetic currents on the boundary of the downstream cavity which is formed are the source of these disturbances which fringe out within the lunella and extend on into the upstream flow to a distance of about the geometric mean Larmor radius. Additional field perturbations and associated currents appear over the upstream hemisphere. The results are in qualitative accord with lunar magnetometer data and bear upon the interaction of the solar wind with small non‐magnetic bodies.
The relationship of energy flow at the magnetopause to geomagnetic activity
Authors: Baker D. N. , Stone E. C.
Published: February 2008

Properties of the energetic electron (E ≳ 200 keV) magnetopause layer along the distant magnetotail have been studied with Caltech instrumentation aboard IMP‐8 for approximately 60 spacecraft orbits. The cross‐sectional area of the layer appears to increase by a factor of ∼ 5 with increasing geomagnetic activity, and the average unidirectional electron flux within the layer increases by a factor of ∼ 4. The energy carried by electrons ≳ 200 keV ranges from ∼ 1014 ergs sec−1 to ∼ 1015 ergs sec−1. Extrapolation to include all electrons > 1 keV suggests total energy flow ranging from ∼ 3×1015 ergs sec−1 at quiet times to ∼ 5×1018 ergs sec−1 at magnetically disturbed times.
Photochemical‐radiative damping and instability in the stratosphere
Authors: Strobel Darrell F.
Published: February 2008

At the stratopause, when opacity effects are included, the photochemical acceleration of the thermal relaxation rate is substantially reduced and large vertical scale temperature disturbances relax at approximately the Newtonian cooling rate. Large vertical scale ozone density and temperature perturbations may grow in amplitude due to opacity changes in the O3 dissociation and heating rates.
The stratospheric abundance of peroxynitric acid
Authors: Jesson J. P. , Glasgow L. C. , Filkin D. L. , Miller C.
Published: February 2008

A recent re‐examination of the kinetics of the reaction of NO2 with HO2 shows this to be a three body reaction leading to the formation of peroxynitric acid (HO2NO2). The rate of formation is such that significant concentrations of HO2NO2 (not previously included in atmospheric models) are expected to form in the stratosphere. In the present study a preliminary determination of the absorption cross section of HO2NO2 is presented. This information is used to calculate theoretical vertical concentration profiles for HO2NO2. It is concluded that peak mixing ratios should be in the range of 1‐3 ppb at 30 km, and that it should be possible to detect this new stratospheric species using infrared techniques.
Ultraviolet absorption spectrum of hydrogen peroxide vapor
Authors: Molina Luisa T. , Schinke Stanley D. , Molina Mario J.
Published: February 2008

The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296°K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 × 10−5 sec−1.
Modes of Gulf Stream intrusion into the South Atlantic Bight Shelf Waters
Authors: Atkinson Larry P.
Published: February 2008

Gulf Stream meanders and the associated vertical motions present water of varying densities at the shelf break along the southeast United States continental shelf. Under certain conditions of wind and Gulf Stream motion the vertically advected, deeper, Gulf Stream waters will intrude into these shelf waters. Depending on the ambient shelf water density the intruding water will override, interleave or form a bottom intrusion. Analysis of available hydrographic data indicates 20°C Gulf Stream water could form a bottom intrusion anywhere along the coast except in January when shelf water densities are relatively higher. 24°C Gulf Stream water could only form bottom intrusions in April through November. The remainder of the year 24°C waters would interleave or override.
Rocket observation of high frequency waves over a strong aurora
Authors: Kellogg P. J. , Monson S. J. , Whalen Brian A.
Published: February 2008

High frequency waves in two frequency bands above the electron gyro frequency (1.6 MHz and 2.3 MHz) were observed by radio receivers carried on a sounding rocket as it passed over a strong aurora. Only the line at 2.3 MHz has a large magnetic component. Both 0.4s and 4s periods are present in much of the emissions. Good correlation is seen for a short time between the 2.3 MHz waves and 1.9 keV electrons detected on board the rocket.
Effect of temperature coupling on ozone depletion prediction
Authors: Chandra S. , Butler D. M. , Stolarski R. S.
Published: February 2008

The effects of chlorine perturbations on both the temperature and the ozone distribution in the stratosphere have been studied using a simplified radiative‐photochemical model. The model solves the hydrostatic equation for total density in a self‐consistent manner as the temperature is changed. Radiative coupling is found to have significant effect on both the thermal structure and the ozone distribution particularly in the 35‐50 km region. By increasing the ClX mixing ratio by 5.0 ppbv, the temperature in this region is decreased by 5K ‐ 10K with a slight increase below 30 km. The local ozone depletion around 40 km due to added ClX is smaller compared to the estimate made by keeping the temperature fixed to the ambient condition. However, the integrated effect of radiative coupling is to increase the calculated column ozone depletion by 15‐25% in this model.
The magnetic field on the magnetospheric boundary from laboratory simulation data
Authors: Podgorny I. M. , Dubinin E. M. , Potanin Yu. N.
Published: February 2008

A simulation experiment has studied the magnetospheric boundary for high Alfven Mach numbers. The artificial magnetosphere was produced as a result of interacting a supersonic and super‐Alfvénic flow of collisionless plasma with the magnetic field of a dipole. In the presence of southward magnetic field components, a "visor" forms at the day side in the plasma flow, preventing reconnection at the front side of the magnetosphere. Field lines of the plasma flow envelop the polar cap, forming the mantle. In the presence of northward field components the convection in the polar cap is sunward, while with southward components convection is antisunward.

Simultaneously with the convection caused by reconnection, convection due to viscous interaction is observed along the boundary, and clearly in the region of closed field lines.
Differential SM/ND evolution in oceanic basalts
Authors: Carlson R. W. , Macdougall J. D. , Lugmair G. W.
Published: February 2008

Measurements of selected samples of ocean floor basalt indicate that the sources of ridge extrusives for three major spreading centers in the Pacific, Atlantic, and Indian Oceans have a similar range of Nd isotopic compositions. However, there is a marked spread in 143Nd/144Nd ratios within this globally distributed reservoir which is evident between oceanic tholeiitic and alkalic basalts as well as between samples of similar chemistry. These differences in 143Nd/144Nd can only be the result of chemical heterogeneities within the ocean ridge basalt (ORB) source that have been maintained for periods which are longer than the lifespan of an active ridge. Basalts from the Lau Marginal Basin have 143Nd/144Nd which is marginally lower than that found for “normal” ORB. Sm‐Nd model ages calculated for primitive oceanic tholeiites suggest a differentiation age of ∼ 1.1 AE for the ORB source, which is similar to estimates obtained from the Rb‐Sr and U‐Pb systems.
Need for a three‐dimensional analysis of magnetic fields in the magnetotail during substorms
Authors: Akasofu S. ‐I. , Lui A. T .Y. , Meng Ching I. , Haurwitz Marion
Published: February 2008

It is shown that in the vicinity of the midplane of the magnetotail the By component and the Bz component (in solar‐magnetospheric coordinates) of the magnetic field during substorms are usually comparable and often vary systematically together. Thus, the usual practice of representing the substorm configuration of the field as lying entirely in the noon‐midnight plane may be misleading.
Possible origins of time variability in Jupiter's outer magnetosphere. 3. Variations in the heavy ion plasma
Authors: Eviatar A. , Kennel C. F. , Neugebauer M.
Published: February 2008

We discuss the implications of a heavy ion plasma in the Jovian magnetosphere. The plasma electron density varies on time scales comparable with that of radial diffusion. This plasma can enhance a super‐Alfvenic planetary wind by increasing the radial mass flux. A mechanism by which the heavy ion plasma can regenerate itself via self‐sputtering from the surface of Io followed by ionization first by solar ultra‐violet and later by electron impact is proposed. We suggest that this long term variability can modulate the faster variations of the plasma‐magnetosphere configuration of Jupiter.
Dayside auroral arcs and convection
Authors: Reiff P. H. , Burch J. L. , Heelis R. A.
Published: February 2008

Recent DMSP and ISIS dayside auroral observations show two striking features: a lack of visible auroral arcs near noon and occasional fan shaped arcs radiating away from noon on both the morning and afternoon sides of the auroral oval. We present a simple model which includes these two features as a consequence of the dayside convection pattern of Heelis et al. (1976). The model may be testable in the near future with simultaneous convection, current and auroral light data.
Magma mixing at mid‐ocean ridges: Evidence from legs 45 and 46‐DSDP
Authors: Dungan Michael A. , Long Philip E. , Rhodes J. M.
Published: February 2008

An integrated petrologic and geochemical study of basalts recovered in Legs 45 and 46 (DSDP) has yielded evidence that these moderately evolved basalts are mixtures of primitive, mantle‐derived tholeiites with more evolved magmas. The hybrid nature of these rocks is recognized on the basis of disequilibrium mineralogy. Plagioclase phenocrysts exhibit substantial diversity in composition and zoning patterns including both normally and reversely zoned grains and abundant textural evidence of resorption. Many olivine and plagioclase phenocrysts are too refractory (e.g., Fo90−88) to be in equilibrium with liquids of the host basalt composition and are in fact of a composition consistent with crystallization from a primitive, mantle‐derived basalt liquid. An estimate of this primitive melt, presumed to be parental to the observed lavas, has been derived from melt inclusions trapped in the olivine phenocrysts. These are characterized by high Ca/Al and low TiO2, two chemical features typical of primitive ocean floor basalts recovered elsewhere in the Atlantic.

We suggest that subvolcanic magma chambers beneath mid‐ocean ridges receive periodic injections of this primitive melt and its attendant phenocrysts which mix with fractionated chamber‐bound magmas, resulting in observed moderately evolved lavas. Chemical modeling of ocean floor basalt differentiation assuming a combination of magma mixing and crystal fractionation alleviates some apparent anomalies encountered in previous studies (Rhodes et al., 1978).
Global tropospheric measurements of mitric acid vapor and particulate nitrate
Authors: Huebert B. J. , Lazrus A. L.
Published: February 2008

Measurements of HNO3 vapor and particulate NO3− were made over continental and marine areas, at altitudes from .2 to 7 km, as a part of Project Gametag. HNO3 vapor was found to be as common over marine areas, far from anthropogenic sources of NOx, as over remote continental regions, ranging from < .02 to .3 ppbv. Urban influenced continental values ranged from .3 to .86 ppbv. Comparable HNO3 was found both above and within the boundary layer, in contrast to theoretical predictions of a negative HNO3 gradient with altitude. In many regions of the troposphere there was more HNO3 vapor than participate NO3−, although the reverse is true in the marine boundary layer, where it appears that heterogeneous chemistry converts HNO3 and Cl− to HCl and particulate NO3−. This rather limited data set suggests an HNO3 lifetime on the order of a few days.
Equatorial adjustment in the eastern Atlantic
Authors: Moore Dennis , Hisard Philippe , McCreary Julian , Merle Jacques , O'Brien James , Picaut Joël , Verstraete Jean‐Marc , Wunsch Carl
Published: February 2008

Observations suggest that the annual upwelling event in the Gulf of Guinea is not associated with changes in the local winds. A possible explanation is that a strong upwelling signal, generated by increased westward wind stress in the western Atlantic, can travel to the eastern Atlantic as an equatorially trapped Kelvin wave. This explanation is analogous to current theories of El Niño in the Pacific Ocean.
High frequency drift waves with wavelengths below the ion gyroradius in equatorial spread F
Authors: Huba J. D. , Chaturvedi P. K. , Ossakow S. L. , Towle D. M.
Published: February 2008

Evidence is given for intense VHF and UHF radar backscatter during equatorial Spread F resulting from irregularities of 1 meter and 36 cm, respectively. The linear theory for high frequency (ω ≳ Ωi, where Ωi is the ion gyrofrequency) drift waves, generated by the drift‐cyclotron and lower‐hybrid‐drift instabilities, is presented. This linear theory is set forth as a possible explanation for the occurrence of these irregularities below the ion gyroradius. The maximum growth for these instabilities occurs for kre ∼ 1, where k is the wavenumber perpendicular to the magnetic field and re is the electron gyroradius. For these instabilities, the growth rate is γ ≳ (me/mi)¼ Ωi and results in growth times less than a second. For typical equatorial Spread F ionospheric parameters, where (νii/Ωi) (kri)² ≳ 1 (νii is the ion‐ion collision frequency, rI is the ion gyroradius), the lower‐hybrid‐drift instability is dominant.
Mars meteorology: Three seasons at the surface
Authors: Ryan J. A. , Henry R. M. , Hess S. L. , Leovy C. B. , Tillman J. E. , Walcek C.
Published: February 2008

We summarize some meteorological results from Viking for northern summer, autumn and winter. Little Sol‐to‐Sol meteorological change was observed during summer, except for secular pressure change. However, a regular sequence of weather disturbances, interpreted as baroclinic waves, appeared primarily at VL‐2 during autumn and winter. The number of Rossby waves present at a given instant is calculated to be 4 and 6 for these seasons. The extreme regularity and low wave number make these systems closely resemble the baroclinic waves of rotating annulus experiments.
Rates of N2O evolution from N‐fertilized soil
Authors: McKenney D. J. , Wade D. L. , Findlay W. I.
Published: February 2008

We have directly measured nitrous oxide flux rates from well aerated agricultural soil (Fox sandy loam and Harrow fine sandy loam) located in Essex County, southwestern Ontario. Evidence was obtained showing that the release of N2O was strongly related to the rate of fertilizer application during the interval 6 to 43 days after soil treatment. Emission rates on NH4NO3 fertilized plots planted to corn were in the range 7.04 × 10−4 to 2.64 × 10−2 kg N ha−1 day−1; rates on more heavily fertilized plots planted to burley tobacco were generally higher in the range 1.45 × 10−3 to 3.20 × 10−2 kg N ha−1 day−1. We briefly discuss our observations in terms of loss of fertilizer nitrogen as N2O and the impact of increasing fertilizer addition on the extent of N2O evolution.
Comparison between in‐situ spectral measurements of F‐region irregularities and backscatter observations at 3 m wavelength
Authors: Woodman R. F. , Basu Sunanda
Published: February 2008

In situ measurements of equatorial electron density irregularities in the F‐region by rockets and satellites have yielded a power‐law form of one‐dimensional wave number spectrum of spectral index 2 in a direction transverse to the magnetic field over a scale size range of several km to several tens of m. Equatorial scintillation measurements in the WHF/UHF band which are most sensitive to irregularities of several km to several hundred m are consistent with the in situ spectral results. The backscatter measurements made at Jicamarca at 50 MHz provide an additional measurement of the spectral power at 3m wavelength. Computations are presented for the backscatter intensity expected from irregularities with power law spectrum in the transverse direction but which are infinitely elongated along the magnetic field. The computed intensity is compared with actual backscatter measurements and correlated scintillation observations. It is found that in order to reconcile the backscatter measurements with the simultaneous VHF/UHF scintillation observations a gaussian type cut‐off of the power‐law spectrum is necessary at m wavelengths near the O+ ion gyro‐radius.
Solitons and second harmonic radiation in type III bursts
Authors: Papadopoulos K. , Freund H. P.
Published: February 2008

The emission at the second harmonic (2ωe) of the plasma frequency from self‐consistent Langmuir solitons is calculated. The theory predicts, in a natural way, the observed transition from the region where the intensity is linearly proportional to the electron flux to the region where the radio intensity is proportional to the square of the electron flux. A detailed comparison of the radiation observed at (2ωe), for the burst of 31 March 1976, 18:10 UT with the one expected on the assumption of radiation from solitons, using the correlated in situ measurements of the electric fields at ωe and their spatial structure provides strong evidence that, for the first time, Langmuir solitons have been observed in space.
Shallow seismicity in subduction zones
Authors: Sacks I. Selwyn , Linde Alan T. , Rodriquez B. A. , Snoke J. Arthur
Published: February 2008

During 1965 the University of San Agustin operated a net of 9 high‐sensitivity seismographs in southern Peru. Stable hypocenters for local earthquakes were determined by an interactive method utilizing both the P and the S arrival times. The hypocenters delineate a 30° dipping Benioff zone but also indicate considerable intraplate activity. Of particular interest is the existence of an aseismic wedge between the shallower earthquakes in the subducting lithosphere and those in the continental lithosphere. Investigations of other regions, e.g., the Aleutians and Japan, suggest that this may be a global phenomenon. We suggest that this aseismic wedge occurs because the compressive stress due to the interaction of the oceanic and continental plates is counterbalanced by tension caused by the downwarping of the continental lithosphere due to the drag of subduction. The unstressed zone (at depths less than 40 km) includes the coastal areas and explains the absence of large shallow earthquakes in that region. Further inland, beyond the region of downwarping, stresses are again adequate to cause large shallow earthquakes.
Simultaneous measurements of midlatitude thermospheric winds at 105° W and 79° W longitude
Authors: Hernandez G. , Sipler Dwight P. , Biondi Manfred A.
Published: February 2008

Simultaneous measurements of neutral winds from the Doppler shifts of the 15867 K (630. nm) emission of the night sky have been made at two midlatitude stations separated by about 26° in longitude and less than 1° in latitude (39.8° N, 105.5°W and 40.13° N, 79.16°W). Comparison of the measured winds show strong local time correlation and negligible universal time correlation, in particular for meridional winds. This behavior is expected for the thermosphere for solar‐minimum, magnetically quiet conditions, when the strongest pressure forces driving the winds are caused by insolation. The results also show the basic assumption of longitudinal or zonal averaging of two‐dimensional thermospheric models to be correct for at least the 26° longitudinal separation between the two stations.
Tidal acceleration of the Moon
Authors: Williams J. G. , Sinclair W. S. , Yoder C. F.
Published: February 2008

The analysis of eight years of lunar laser ranging data yields a value for the tidally induced secular acceleration of the lunar orbital longitude of. For semidiurnal tidal frequencies this corresponds to a terrestrial Q = 12 ±2. The error inis dominated by noise in the data and its modeling. The error is expected to decrease significantly as future data become available and it may become possible to detect an 18.6 yr periodic modulation of the acceleration which would allow the separation of the effects of diurnal and semidiurnal tides. Comparison of n given here with values published from the analysis of classical astronomical observations does not show a significant difference which can be attributed to a changing gravitational constant.
Martian lithospheric thickness from elastic flexure theory
Authors: Thurber C. H. , Toksöz M. N.
Published: February 2008

The thickness of the elastic lithosphere in the Tharsis region of Mars is estimated from effects due to the surface load of Olympus Mons. Deformation (vertical displacement) and stress are calculated using elastic flexure theory for a range of possible lithospheric thicknesses (T), modeling the lithosphere as a thin elastic shell and the interior as a Newtonian fluid. For T < 150 km, displacement and stress rise rapidly with decreasing thickness. For T near 100 km, deformation of the region surrounding the volcano would be clearly visible in the topography, and resulting tensional stresses exceeding 5 kbar should produce observable fracturing at the surface. In contrast, for T near 200 km deformation is minimal and the tensional stress, being less than a kilobar, would not result in extensive fracturing. Since significant deformation and fracturing are not observed, it is concluded that the Martian elastic lithosphere is at least 150 km in thickness. Seismic, tectonic, and gravity observations all suggest a thick Martian lithosphere as well.
Dynamic fracture strength of rock
Authors: Grady D. E. , Hollenbach R. E.
Published: February 2008

Dynamic fracture strengths of a representative suite of crustal rocks have been determined. The rocks investigated included silicates and carbonates of varying grain size and porosity, oil shale with several kerogen contents and orientations, and fused silica. With the exception of fused silica, fracture strengths ranged from a few tens of MPa to slightly over 100 MPa. Rate dependence of fracture stress and fracture energy appears to be important in determining the dynamic strength of rock.
Past and present day tropospheric fallout fluxes of Pb, Cd, Cu, Zn and Ag in Antarctica and Greenland
Authors: Boutron Claude
Published: February 2008

Estimates of the present day tropospheric fallout fluxes of Pb, Cd, Cu, Zn and Ag in the central areas of Antarctica and Greenland are calculated from the measured concentrations of these elements in the deposited snow. The fluxes obtained are higher by one to two orders of magnitude in Greenland, probably largely because of the different geographical locations and meteorological regimes of Greenland and Antarctica. The variations of these fluxes during the last century suggest that the present day enrichments of these five metals in tropospheric aerosols in remote areas are not influenced significantly by human activity, but may be for a small part for Pb and Zn in the Northern Hemisphere, and are therefore linked to natural processes.
Direct observation of a tangential electric field component at the magnetopause
Authors: Mozer F. S. , Torbert R. B. , Fahleson U. V. , Fälthammar C.‐G. , Gonfalone A. , Pedersen A. , Russell C. T.
Published: February 2008

The first direct, in situ measurements of the quasi‐static electric field at and near the magnetopause, in the magnetosheath, bow shock, and solar wind, have been made on the ISEE‐1 satellite. Both the large scale average electric field and the fine scale field observed during a magnetopause crossing show the existence of significant tangential electric field components on both sides of the magnetopause, in agreement with the requirements of reconnection theories. The data in the satellite frame also show significant normal electric field components that typically point towards the magnetopause on both sides, corresponding to
plasma flows towards dawn, as expected for the pre‐noon magnetopause crossings. In combination with ISEE‐1 and ISEE‐2 magnetic field data, these measurements also suggest that a magnetopause passage over the spacecraft occured at a velocity of 20±10 km/s, that the magnetopause thickness was 300±150 km, and that the local Ī·Ē dissipation was 70±20 watts/km². This observed local level of power dissipation would correspond to a total power of 1012 watts, if it existed over the entire front of the magnetopause.
Nitrite and static stability in the coastal waters off Peru
Authors: Barber Richard T. , Huyer Adriana
Published: February 2008

A strong secondary nitrite maximum was observed at 15°S off the coast of Peru in August 1976. Since the secondary nitrite maximum does not coincide with a maximum in stability where sinking particulate organic material would accumulate, the hypothesis that the depth of nitrite accumulation is determined by the concentration of organic substrates on a density discontinuity is not tenable. Instead, the nitrite maximum coincides with a stability minimum within the core of the southward‐moving Equatorial Subsurface Water in the Peru‐Chile Undercurrent.
Buoyancy waves in the troposphere: Doppler radar observations and a theoretical model
Authors: VanZandt T. E. , Green J. L. , Clark W. L. , Grant J. R.
Published: February 2008

On 15‐16 April 1976 a polar‐front jet stream with northward winds as large as 70 m/s passed over Colorado. Profiles of the radial component of the velocity vr and refractivity turbulence structure constant Cn² were observed by the Sunset VHF pulsed Doppler radar, near Boulder, CO, from near the ground up to about 15km, with 67s time resolution and lkm height resolution. While the jet stream was overhead, vr and Cn² fluctuated continuously with time scales from a few minutes up to hours. On several occasions coherent wave trains with periods ranging from 4 to 8 minutes were observed. The corresponding pressure perturbations at the ground were measured by a nearby microbarograph array. One of these events is discussed here.

These observations are compared with the results of a linear stability analysis of the background wind and temperature profiles. The theoretical predictions of the period, wavelength, and phase speed, and the corresponding height variations of the phase and amplitude of the perturbation velocity along the radar beam all agree well with the observations. This agreement demonstrates that (1) the short‐period waves were generated by shear instability on the bottom of the jet stream and (2) linear theory can adequately describe many features of buoyancy waves generated by dynamic instability.
Diurnal variability in the concentration of nitrous oxide in surface air
Authors: Matthias A. D. , Blackmer A. M. , Bremner J. M.
Published: February 2008

Significant diurnal variations in the concentration of nitrous oxide (N2O) in surface air were detected by analysis of air samples collected at two sites in Iowa. At both sites, the highest concentrations of N2O were observed during early morning hours. The diurnal variations observed decreased with increasing height above ground level and indicated that soil in the areas studied was a source of atmospheric N2O. They differed markedly from the variations detected in recent work leading to postulation of the existence of a major ground surface sink for atmospheric N2O.
The mechanical property of montmorillonite clay at high pressure and implications on fault behavior
Authors: Wang Chi‐yuen , Mao Nai‐hsien , Wu Francis T.
Published: February 2008

Preconsolidated montmorillonite clay was deformed up to 30% strain at confining pressures up to 4 kb (400 Mpa) under undrained conditions. The deformation was characterized by plastic yield, strain hardening, a broad peak strength at large strain, and a gradual decline in strength thereafter. In some cases the sample was ruptured, with stress drop of the order of 0.1 kb. At confining pressures greater than 2 kb, the peak strength was about 0.35 kb and did not depend markedly upon confining pressure. These results may have important implications on the stability and the strength of faults.
Determination of the sources and sinks of N+ ions in the thermosphere
Authors: Torr D. G. , Torr M. R. , Hanson W. B. , Hoffman J. H.
Published: February 2008

Measurements of atmospheric parameters made by the Atmosphere Explorer‐C satellite are used to identify mechanisms for the production and loss of N+ ions in the ionosphere. The main source below 250 km is found to be photo‐dissociative ionization of N2. Above 250 km the reaction

urn:x-wiley:00948276:media:grl1079:grl1079-math-0001
is dominant; k1 is found to be 5 −2+7 × 10−11cm³s−1. A possible minor source of N+ is the reaction

urn:x-wiley:00948276:media:grl1079:grl1079-math-0002
where k2 = 1 −.5+1 × 10−10cm³s−1. Photoionization of N(4S) and dissociative charge exchange of He+ with N2 constitute detectable sources above 350 km. Charge exchange of N+ with O is identified as a significant sink above 300 km. The rate coefficient for this reaction is 5 −2+7 × 10−13 cm³s−1
Iue detection of sulfur dioxide in the atmosphere of Venus
Authors: Conway Robert R. , McCoy Robert P. , Barth Charles A. , Lane Arthur L.
Published: February 2008

Ultraviolet absorption bands of sulfur dioxide have been detected in the reflectance spectrum of Venus using the high resolution spectrometer of the International Ultraviolet Explorer (IUE). The identification of these bands in the 2080 to 2180 A range has been verified by comparison with laboratory absorption spectra. An estimate of the SO2 vertical column density using a reflecting layer model is 4 × 1016 cm−2.
Pitch angle distributions of energetic protons near the Earth's bow shock
Authors: Scholer M. , Gloeckler G. , Ipavich F. M. , Hovestadt D. , Klecker B.
Published: February 2008

Measurements of energetic protons between ∼ 28 and ∼ 145 keV on ISEE‐1 upstream and downstream of the earth's bow shock during times of a radial interplanetary magnetic field are presented. The protons exhibited a slight anti‐sunward flow in the spacecraft system in front of the bow shock and a strong flow along the magnetic field in the spacecraft system in the magnetosheath. Compton‐Getting transformations of these anisotropies into the plasma frame of reference have been performed. It is argued that the observations can be explained best in terms of particle acceleration by multiple reflection between the bow shock and upstream scattering centers.