bluuebunny/crossref_metadata_2025 huggingface dataset:
On Transport in Porous Formations Characterized by Heterogeneity of Evolving Scales
Authors: Bellin Alberto , Pannone Marilena , Fiori Aldo , Rinaldo Andrea
Published: February 2008

Solute transport in natural formations at the regional scale is influenced by several scales of heterogeneity which correspond to the presence of several geological units called facies. As customarily assumed in stochastic theories, inside the facies the transport can be characterized by a single scale of heterogeneity. At the regional scale several geological units are present such that a hierarchy of relevant scales needs to be defined. A possible model for this spatial variability assumes the log conductivity as a random space function of stationary increments characterized by a power law semivariogram. With this hypothesis the ergodic dispersion coefficient grows unbounded as time increases, leading to the phenomenon called anomalous dispersion. An alternative approach considers the plume in nonergodic conditions and assumes the effective dispersion coefficient, which is defined through differentiation in time of the expected value of the spatial second‐order plume moment, as representative of macrodispersion. Large differences have been observed in the resulting plume spreading while approaching the problem using the above alternative definitions. In this paper we provide first‐order analytical solutions for the longitudinal effective dispersion coefficient, DL, as well as for the expected value of the longitudinal spatial plume moment, 〈S11〉, that complement semianalytical expressions recently proposed in literature. Furthermore, we provide a semianalytical expression for the standard deviation of the longitudinal second‐order moment which is important in assessing the interval of confidence of the estimation provided by 〈S11〉. Suitable numerical simulations are performed to validate analytical and semianalytical expressions as well as to assess the impact of the cutoff in the log conductivity power spectrum imposed by choosing a finite domain dimension. We conclude that according to recently published results, the dispersion is anomalous when the Hurst coefficients, H, is larger than 0.5 while it is Fickian for H < 0.5. This is in contrast with the ergodic analysis which concludes that the dispersion is anomalous irrespective of the Hurst coefficient. Hence the effective dispersion coefficient is more effective than the ergodic dispersion coefficient to represent the plume spreading. However, the standard deviation of the longitudinal spatial second‐order moment is of the same order of magnitude as the expected value leading to the conclusion that the estimations provided by DL and 〈S11〉 are affected by large uncertainties. Numerical results are in good agreement with the analytical solutions, and under some hypotheses they are not influenced by the cutoff. This is not the case for the ergodic second‐order longitudinal moment, which strongly depends on the imposed cutoff.
An Analytical Framework for the Water Budget of the Unsaturated Zone
Authors: Kim C. P. , Stricker J. N. M. , Torfs P. J. J. F.
Published: February 2008

In this contribution an analytical framework is put forth for the water budget of the unsaturated zone. The most important assumptions made are (1) an instantaneous redistribution of moisture and (2) a linear relationship between evapotranspiration and relative soil saturation. For storm periods, infiltration is described using the well‐known solution of Philip [1957] in conjunction with the time compression approximation. For interstorm periods a new solution is derived for the moisture depletion of a soil water reservoir that experiences simultaneous evapotranspiration and percolation. The framework compares favorably with numerical solutions of Richards' equation for a wide variety of climate conditions and soil hydraulic properties. Its simplicity and computational efficiency make the framework well suited for the analysis of the impact of spatial soil and rainfall heterogeneity on the water budget of the unsaturated zone.
Generation of Langmuir circulation for nonaligned wind stress and the Stokes drift
Authors: Polonichko Vadim
Published: February 2008

The growth rate of Langmuir cells is calculated from a linear stability analysis for different orientations of wind, waves, and cells as well as for various values of the dimensionless parameters describing wave‐current interaction. These parameters could be the Stokes drift/friction velocity ratio and the shear ratio Sr which describes the relative strength of the Stokes drift shear and mean Eulerian shear. The growth rate is maximal overall when wind and waves are aligned. For a given angle between the Stokes drift and the wind (the misalignment angle), the direction of the cell axis for maximal growth lies between wind and waves and is mainly determined by (1) the misalignment angle and (2) the shear ratio. For a fixed value of the latter, the orientation of the fastest growing cells (the preferential cell direction) is nearly independent of the one other dimensionless parameter which could be the Stokes drift/friction velocity ratio or the Langmuir number. The direction of the fastest growing cells shifts closer toward the wave direction as the Stokes drift shear increases relative to the mean shear and vice versa. However, while the preferential cell direction lies close to the wind for small Sr, it does not align with the waves for reasonably large Sr. When wind and waves are not aligned and the Stokes drift shear and the mean shear are of the same order, the cells drift sideways at an angle to the cell axes, with a speed which is comparable with the magnitude of the mean Eulerian current at a depth of approximately 0.7 times the cell depth. The drift amplitude increases as the misalignment angle increases and is larger for larger values of the shear ratio. When wind and waves are oriented in the opposite directions, there is no source of instability, and the cells are damped.
Methane hydrates and global climate
Authors: Kvenvolden Keith A.
Published: February 2008

Methane hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. The amount of methane sequestered in gas hydrates is probably enormous, but estimates of the amounts are speculative and range over three orders of magnitude (about 103 to 106 GT (gigatons = 1015 g)). A question of current interest concerns the possible consequences of an addition of methane to the atmosphere from destabilized methane hydrates due to global warming. Models of greenhouse warming predict that climatic change will be greatest in the Arctic. Thus, if methane from destabilized gas hydrates contributes to greenhouse warming, this destabilization will most likely take place first in the Arctic, particularly in the shallow nearshore regions of the Arctic Ocean where offshore permafrost is found. The process of permafrost warming and release of methane from gas hydrates may already be in progress, but the amount being released now and to be released in the 21st century is probably small. The positive feedback of this atmospheric methane on global climates will likely be minimal.
A time‐dependent budget model for nutrients in the Baltic Sea
Authors: Wulff Fredrik , Stigebrandt Anders
Published: February 2008

Overall budgets for nutrient and humus are described for the Baltic Sea as well as for the subsystems, i.e., the Baltic proper, the Bothnian Bay and the Bothnian Sea. The residence times for total phosphorus, total nitrogen, silicate and humus are 13.3, 5.5, 11.2 and 9.6 years respectively, compared to 21.8 years for a conservative substance (salt). About 90% of the nutrient losses are due to biogeochemical sinks within the Baltic Sea. Thus only about 10% is exported to external areas (the Kattegat/Belt Sea). For humus the corresponding figures are about 75 and 25%, respectively. This means that the Baltic Sea to a large extent can be regarded as a closed system and perturbations in the water exchange with the North Sea should have little effect on the nutrient budgets. The sinks are parameterized by an expression borrowed from limnology where the net nutrient loss is a function of the winter surface concentration. A budget model is run in a prognostic, hindcast mode with the assumed time‐dependent phosphorus and nitrogen loading of the Baltic proper. The computed development of the winter surface concentrations of total P and total N for the period 1950‐1988 appears quite realistic. The possibility of having variable sinks which are functions of the surface winter concentrations of nitrogen and phosphorus is described using calculations based on data from the different Baltic subareas. Such sinks should significantly decrease the winter N:P ratio in the surface water when the nutrient loading increases with time. With better descriptions of in particular the pools of nutrients in the sediment, it would be possible to model future changes of nutrient concentrations in the water column in relation to loading.
The changing patterns of ΔpCO2 between ocean and atmosphere
Authors: Volk Tyler , Bacastow Robert
Published: February 2008

The average difference between the partial pressure of CO2 in ocean surface water and the overlying atmosphere (ΔpCO2 = pCO2,ocean) ‐ pCO2,atm) has been changing ever since the beginning of the anthropogenic era due to the dumping of CO2 as a waste gas into the atmosphere. However, the change in the difference has not been uniform over the surface of the oceans. This work assesses regional variations in the Earth scale patterns of sources (ΔpCO2>0) and sinks (ΔpCO2<0) during this anthropogenic transient. The regional correction, ΔpCO2*, is defined as the quantity that must be added to a region's preanthropogenic ΔpCO2 to give its present value. Using a five‐box ocean model with special surface regions for the prominent equatorial Pacific source and north Atlantic sink, we show that a larger magnitude of ΔpCO2* is necessary for these two regions than for the average ocean. Analytical results with a multiple one‐and‐one‐half‐box model, in which horizontal water exchanges are neglected, indicate that the ratio Of ΔpCO2* values for any two regions should vary inversely with the ratio of their gas exchange coefficients and nearly directly with the ratio of their deep‐to‐surface water piston velocities. The ΔpCO2* values for regions of the five‐box model vary by as much as a factor of six; predictions of the multiple one‐and‐one‐half‐box model are within a factor of two. Discrepancies from these predictions are believed to be due to horizontal and intermediate‐depth water exchanges, which tend to equalize the ΔpCO2* values. Our best estimate is that regions with large vertical water exchanges (equatorial and high‐latitude zones) and/or low gas exchange coefficients (equatorial zones) have ΔpCO2* magnitudes at least twice as large as the magnitude of ΔpCO2* for the average global ocean.
Iron deficiency limits phytoplankton growth in Antarctic waters
Authors: Martin John H. , Fitzwater Steve E. , Gordon R. Michael
Published: February 2008

Enrichment experiments were performed in the Ross Sea to test the hypothesis that iron deficiency is responsible for the phytoplankton's failure to use up the luxuriant major nutrient supplies found in these and all other offshore Antarctic ocean waters . Nitrate uptake rates in the controls without added trace elements ranged from 0.58 to 1.22 μmol kg−1 d−1; the addition of 1 to 5 nmol of unchelated Fe per liter resulted in rates that were 2 to 10 times higher (2.54 to 6.00 μmol NO3 kg−1 d−1). Rates in bottles with 2 nmol Mn added were identical to those in the controls (0.57 to 1.04 μmol NO3 kg−1 d−1). Total decreases in NO3 were balanced by increases in particulate organic N. These results suggest that Fe deficiency is the primary reason that the present‐day southern ocean biological pump is shut off. In contrast, iron was 50 times more abundant during the last glacial maximum; greater Fe availability may have stimulated the biological pump and contributed to the ice age drawdown of atmospheric C02. These results also imply that large‐scale southern ocean Fe fertilization is feasible, at least in terms of the total amounts of Fe required; i.e., 100,000 to 500,000 tons yr−1.
Diurnal CO2 exchange and photosynthesis of the Samoa tropical forest
Authors: Ryan Steven
Published: February 2008

The exchange of CO2 between the atmosphere and tropical forest ecosystem of American Samoa was continuously monitored for 3 days in December 1988. The island was modeled as a simple wind‐ventilated respiration chamber with CO2 input concentration, CO2 output concentration, and residence time as measured variables. Net ecosystem production rates were calculated by incorporating Gaussian vertical diffusion into the model. Nighttime respiration averaged 0.34 (±0.06) g C m−2 h−1; peak midday uptake was 0.85 (±0.23) g C m−2 h−1 . Thirty‐nine percent (±30%) more carbon was assimilated by the ecosystem during the day than was released at night. The diurnal net ecosystem production averaged 1.5 g C m−2 d−1. The daytime CO2 exchange rate varied as the logarithm of incident solar radiation over a range of 30 W/m2 to 900 W/m2, with r2 = 0.87. Total ecosystem respiration equaled photosynthesis at a radiation intensity of 72 (±14) W/m2. The saturation intensity was 600 W/m2.
Summary of meteorological conditions over the North Atlantic Ocean during GCE/CASE/WATOX
Authors: Stunder B. J. B. , Artz R. S. , Rolph G. D. , Harris J. M. , Merrill J. T.
Published: February 2008

During the summer of 1988, a team of scientists aboard the NOAA ship Mt. Mitchell and the NOAA King Air aircraft investigated the spatial distributions of sulfur, nitrogen, and related species and their interactions over the North Atlantic Ocean. In support of these measurements, meteorological data from the National Meteorological Center and from rawinsonde data obtained from the ship were archived and back trajectories were calculated. A summary of the meteorological conditions during the cruise is presented using synoptic maps, soundings, cross sections, and isobaric and isentropic back trajectories. Since day‐to‐day variability of the synoptic situation was generally small, one representative day was chosen to illustrate the overall meteorology. During the cruise, three synoptic regimes were encountered: (1) north of the polar front, (2) under the Bermuda/Azores high, and (3) under the Intertropical Convergence Zone (ITCZ). Soundings from three different days illustrate these regimes. Boundary layer depth and cloud layers were also estimated from all the soundings. Cross sections of temperature, wind, and relative humidity describing the vertical structure of the atmosphere along the cruise show the general day‐to‐day uniformity except near the polar front and near the ITCZ boundary. The back trajectories show general air flow patterns and the land mass source regions of air reaching the ship within three days. For parts of the cruise, air reached the ship from North America, Iceland or Greenland, Africa, and South America.
Vertical profile of elemental concentrations in aerosol particles in the Bermuda area during GCE/CASE/WATOX
Authors: Ennis G. , Sievering H.
Published: February 2008

During the 1988 Global Change Expedition/Coordinated Air‐Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX) joint effort, research was conducted to determine elemental concentrations in atmospheric aerosol particles near Bermuda, to construct a three‐level (15, 150, and 2600 m ASL) vertical profile of these concentrations, and to ascertain the source of the particles. Samples were collected by the NOAA King Air aircraft and NOAA ship Mt. Mitchell on July 24–28, 1988. Concentration determinations were made for 16 elements through the use of an X ray fluorescence instrument designed for analysis of small‐mass samples. A layering effect was found; concentrations of several elements at 150 m were more than twice their respective concentrations at 15 m and 2600 m. Enrichment factors, V/Mn ratio, and correlations between concentrations suggest a Saharan mineral source, despite air mass back trajectories that show no direct continental input for up to 10 days prior to sample collection. Estimated total mineral aerosol concentrations at 15 m, 150 m, and 2600 m are 1.5, 4.1, and 2.1 μg m−3.
PKIIKP and the average velocity of the inner core
Authors: Massé R. P. , Flinn Edward A. , Seggelke R. M. , Engdahl E. R.
Published: February 2008

The phase PKIIKP, which is once reflected from the underside of the inner core boundary, was detected at LASA for a large Novaya Zemlya event at an epicentral distance of 63°. The detection was verified by a technique similar to the VESPA process. Clear arrivals for the phases PcP, P2KP, P4KP, and P7KP were also observed. The near‐side reflection PKiKP was unfortunately not observed for this event, but it is nevertheless possible to estimate the compressional velocity in the upper half of the inner core by using the differential PKIIKP‐PcP travel time. Using this single observation, we estimate the average velocity in the outer half of the inner core to be 11.0 km/sec. This number changes by less than 0.1 km/sec for variations in inner core radius from 1215 to 1230 km, for possible errors in the observed differential times of several seconds, and for reasonable differences in the outer core velocity model (Gilbert et al., 1973, vs. Jordan, 1972). A travel time table for PKIIKP is given.
Preliminary four wavelength nephelometer measurements at Mauna Loa Observatory
Authors: Bodhaine B. A. , Mendonca B. G.
Published: February 2008

A 4λ nephelometer has been included as part of the aerosol monitoring program at Mauna Loa Observatory, Hawaii. This instrument is capable of measuring the clean air (nighttime downslope wind conditions) aerosol light scattering coefficient of bsp ≃ 3 × 10−7m−1, about 1% of the molecular scattering of air. Typical light scattering values for “dirty” (upslope wind) conditions are of the order of bsp ≃ 5 × 10−5m−1. Although rare, vigorous fountaining at Kilauea Volcano occasionally ejects particulate into the upper air and encroaches upon the clean air at Mauna Loa. However, volcanism does not interfere significantly with the background monitoring program. The aerosol size information obtained from the 4λ nephelometer functions as an indicator of the aerosol source and therefore of possible global trends in aerosol size or concentration.
The thickness of the asthenosphere deduced from the motion of the Hawaiian Hot Spot
Authors: Forristall G. Z.
Published: February 2008

It now appears that hot spots do not provide a fixed reference frame for plate motions. However, if individual hot spots trace the motion of particular zones in the mantle, knowledge of their motions can give insight into the kinematics of the deeper flow. The motion of the Hawaiian hot spot with respect to the plate is calculated from seamount ages, and the absolute northward motion of the plate is given by paleoequator positions. In a fixed reference frame, the southward velocity of the hot spot is comparable to the northward motion of the plate. For a simple two‐layer convention model, the zone of return flow (asthenosphere) must then be about twice as thick as the plate.
Compositions of synthetic augite and hypersthene coexisting at 810°C: Application to pyroxenes from lunar highlands rocks
Authors: Lindsley D. H. , King H. E. , Turnock A. C.
Published: February 2008

Hydrothermal experiments on synthetic Ca‐Mg.‐Fe pyroxenes at 810°C and Pfluid = Ptotal = 15 kbar show that augites coexisting with orthopyroxene range in CaSiO3 content from 43 ± 1 mole percent (Fe/Fe+Mg = 0.18) to 38±1 mole percent (Fe/Fe+Mg = 0.75). Experimentally determined distribution coefficients KD = (XMgHyp · XFeAug)/(XFeHyp · XMgAug) are compatible with a constant value 0.690, but probably increase with increasing bulk Fe/Fe+Mg.

If the CaSiO3 content of augites is insensitive to total pressure, these data may be used to estimate temperatures of equilibration for coexisting natural pyroxenes that are low in “non‐quadrilateral” components such as Al, Ti, Mn, and Cr. In particular, many lunar metamorphic rocks appear to have equilibrated to temperatures of 800°C and lower. These results support the view that there has been profound thermal metamorphism of the lunar crust in the interval 4.6 to approximately 4.0 G.y.
Fluorocarbon tracers in hydrology
Authors: Thompson G. M. , Hayes J. M. , Davis S. N.
Published: February 2008

Fluorocarbons are a stable, non‐reactive, and generally non‐toxic group of chemicals which can be detected in concentrations of 1 part per 1012 by electron capture gas chromatography. A fluorocarbon, freon 11, has been used widely as an aerosol propellant during the past 15 years. Its presence in ground water should indicate recent recharge of the water from atmospheric sources. Another fluorocarbon, which is not as yet detectable in the hydrosphere, has been tested for its suitability as a tracer in streams and ground water. This compound, perfluoro‐1, 3‐dimethyl‐cyclohexane, appears useful for measuring stream discharge and detecting the direction of ground‐water flow.
On the measurement of the remanent magnetism of long cores
Authors: R. Dadson , Fuller M. , Pilant W.
Published: February 2008

The remanent magnetism of long cores has been determined with a resolution of better than 3 cms, using an SCT (Superconducting Technology Inc.) cryogenic magnetometer and a computer deconvolution scheme. The three component magnetometer has a horizontal sample access hole through which the core is passed. The instrument output may be regarded as a convolution of the magnetic fields due to a continuous series of small slices with the waveform representing the response of the instrument to one of the slices. By deconvolution of the instrument output with the system response for the small slice, one obtains an approximation to the point values of magnetization along the core. The method has been checked using a “long corer” from the Tatoosh intrusion which had previously been cut into 2 cm sections that were measured as individual standard samples on a spinner magnetometer. Ocean sediment cores have also been measured. It appears that the high sensitivity and low drift of the instrument gives effectively noise‐free data, which permits useful deconvolution.
The measurement of chemically reactive atmospheric constituents by mass spectrometers carried on high‐speed spacecraft
Authors: Nier A. O. , Potter W. E. , Kayser D. C. , Finstad R. G.
Published: February 2008

The quasi‐open‐source mass spectrometer carried on the Atmosphere Explorer‐C satellite has a mode of operation which utilizes the velocity of the vehicle (∼ 8.5 km/sec near perigee) to distinguish between incoming ambient particles and ambient particles which have struck instrument surfaces and become accommodated. Utilization of this mode has made possible the simultaneous measurement of atomic and molecular ambient oxygen without the ambiguity which usually arises due to surface reactions in the instrument. The method appears promising as a means for analyzing planetary atmospheres or the gas surrounding comets.
Molecular and isotopic composition of two seep gases from the Gulf of Mexico
Authors: Brooks James M. , Gormly James R. , Sackett William M.
Published: February 2008

Gas samples collected on the Texas‐Louisiana continental shelf from two natural seeps had molecular (methane > 99%) and isotopic (δ13CPDB ∼ −60‰) compositions highly indicative of a biogenic origin.
Magnetohydrodynamic waves in the magnetosphere and the photon rest mass
Authors: Lanzerotti L. J.
Published: February 2008

Detailed measurements of the parameters of a shear Alfvén wave in the earth's magnetosphere have allowed a limit of ≲ 2.4 × 10−48 gm to be placed on the rest mass of the photon (Mph). This limit is comparable to that determined recently by Hollweg from statistical properties of Alfvén waves in the solar wind (≲1.3 × 10−48 gm) and, together, the two limits represent the best present upper limits to Mph as derived from measurements of magnetohydrodynamic waves.
Empirical radiance corrections: A technique to improve satellite soundings of atmospheric temperature
Authors: Weinreb M. P. , Fleming H. E.
Published: February 2008

Atmospheric temperature profiles deduced from radiation measured from orbiting satellites often disagree systematically with in situ soundings by radiosondes. From comparisons between satellite and radiosonde soundings we derive empirical adjustments to the values of radiance measured at the satellite. In a test with real data the adjustments improved the agreement between satellite soundings and radiosondes. This test also showed that radiance adjustments were more effective than transmittance adjustments.
Comment on “Stacking marine magnetic anomalies: A critique” by Robert L. Parker
Authors: Blakely Richard J. , Cox Allan
Published: February 2008

Noise in marine magnetic anomalies becomes significant at wavelengths below about 3 km. Stacking (or averaging) together reasonable numbers of marine profiles in order to enhance two‐dimensional anomalies at the expense of noise does not appreciably reduce this critical wavelength. It is shown, however, that such short wavelengths are of negligible importance to the waveform of the anomaly and that, if the noise is random, stacking substantially improves the anomaly‐to‐noise ratio for longer wavelengths. For non‐random noise, such as two‐dimensional topographic features, it is essential to compare data from widely separated regions to discern actual paleofield changes recorded by the ocean crust.
Anthropogenic alteration of sedimentary organic carbon
Authors: Gormly J. R. , Sackett W. M.
Published: February 2008

Gradients of the amounts and carbon isotope compositions of the lipids and total organic carbon were observed in the near surface sediments around an offshore production platform in the Gulf of Mexico. The gradients may be due to the presence of petroleum‐derived residues from cuttings‐derived material redeposited during drilling operations or from a spill of some 30,000 barrels of petroleum that occurred at the platform three years earlier.
Surface circulation patterns off the East Coast of Greenland as deduced from satellite photographs of ice floes
Authors: LaViolette P. E. , Hubertz J. M.
Published: February 2008

Satellite photographs for the period 13 August through 6 September 1973 show both north and south movement of ice floes off the east Greenland coast between 74° and 80°N. The paths of seven large (approximately 25 km diameter across) ice floes tracked through the entire period, and a number of smaller floes tracked through portions of the period, indicate the presence of anticyclonic surface eddies in the waters covering the coastal shelf area.
Nonlinear theory of gravity waves and enhanced diffusion in the atmosphere
Authors: Weinstock J.
Published: February 2008

A nonlinear calculation is made of the saturated (self‐limited) fractional density fluctuation δρ/ρo of gravity waves. The result is δρ/ρo = (γ−1)/[1 + 0.4·γ²kz² H²Δ]½, γ = specific heats ratio, kz = vertical wave no., H= scale height, Δ ∞ spectral width of gravity waves. This calculation is based on a method developed for plasma waves. In addition, a calculation is made of the enhancement of atmospheric diffusion by finite amplitude gravity waves. It is shown that such diffusion is very much anisotropic and has the proper magnitude to explain some observations in the mesosphere.
FMR thermomagnetic studies up to 900°C of lunar soils and potential magnetic analogues
Authors: Morris Richard V. , Gibbons Rex V. , Hörz Friedrich
Published: February 2008

Using a recently developed furnace, ferromagnetic resonance (FMR) thermomagnetic studies up to 900°C were employed to measure the Curie points of the superparamagnetic (SP) and single domain (SD) particles in lunar soils and potential magnetic analogue materials. Based on measured Curie points of 775±10°C, the SP and SD particles in lunar soils 10084‐853, 12070‐29, 14161‐46, and 67010‐4 are essentially pure metallic Fe. Synthetic and terrestrial samples containing magnetite, titanomaghemites, and magnetite‐like particles have measured Curie points <600°C are thus not magnetic analogues of lunar soils.
³He/4He ratios in the lower radiation belt as measured by trapped particles in a recovered satellite
Authors: Warasila R. L. , Schaeffer O. A.
Published: February 2008

Helium −3 has been found in the aluminum antenna housing from the recovered second stage of a pre‐Apollo Saturn test flight launched January 28, 1964 and returned to earth on April 28, 1966. The amount of ³He found is about 6 × 10−10 cc (STP)/cm² with a 4He/³He ratio of 145 or less. The ³He is shown to come from the lower radiation belt as all other sources of ³He are orders of magnitude lower than the observed value. We suggest that there is a significant component of low energy flare particles in the radiation belts, although it is impossible to rule out other origins.
Ice nuclei produced by laboratory cultured marine phytoplankton
Authors: Schnell R. C.
Published: February 2008

Concentrations of ice nuclei of up to 106 per gram active at −10°C have been obtained from cultures of laboratory stocks of phytoplankton. Some of the nuclei obtained were active at temperatures as warm as −3°C. These observations support earlier work indicating that zones of profuse marine phytoplankton growth may release large numbers of ice nuclei into the atmosphere.
Comments on Darrell F. Strobel's Discussion of paper by S. S. Prasad and A. Tan “The Jovian ionosphere”
Authors: Prasad Sheo S.
Published: February 2008

Examination of the viewpoints expressed by Strobel reveal several inconsistencies which show that his conclusions are not well founded, and certainly do not provide any substantial justification for ignoring the possible role of CH3 photoionization in the Jovian ionosphere, at least at this time.
Electrical resistivity of granite in frictional sliding: Application to earthquake prediction
Authors: Wang C. Y. , Goodman R. E. , Sundaram P. N. , Morrison H. F.
Published: February 2008

The electrical resistivity of a saturated granite during frictional sliding showed clear variations premonitory to the occurrence of stick‐slip: Resistivity decreased by a few percent with increasing shear stress; the minimum coincided with a sudden release of shear stress of a few bars, accompanied by an immediate return of resistivity. This sequence of changes of resistivity bears some similarity to those observed in the field prior to the occurrence of some earthquakes and suggests that the causative mechanisms for both the field and the laboratory phenomena might be closely related. Further field application of the electrical method for earthquake prediction seems desirable.
Atomic nitrogen densities in the thermosphere
Authors: Torr D. G. , Torr M. R. , Rusch D. W. , Hays P. B. , Mauersberger K. , Walker J. C. G. , Spencer N. W. , Hedin A. E. , Brinton H. C. , Theis R. F.
Published: February 2008

Recently atomic nitrogen densities of ∼106cm−3 were measured at 400 km by the open source mass spectrometer on the Atmosphere Explorer‐C satellite (AE‐C). Daytime N densities ∼5 × 107cm−3 at 160 km have also been inferred from airglow and other measurements on AE‐C. We show that atomic nitrogen densities of this magnitude result in significantly lower values for the O2+ concentration than those measured on AE‐C over the altitude range to 160 to 200 km, because of the removal process O2+ + N k3 → NO+ + O. We show that the discrepancy can be explained in terms of latitudinal variations in both the N and O2 densities. We also present evidence which indicates that k3 could be as low as 1 × 10−10cm−3 at ionospheric temperatures.
Polar enhancements of nightglow emissions near 6230A
Authors: Reed Edith I.
Published: February 2008

Night airglow emissions near 6230A, as observed from the Ogo 4 spacecraft in 1967‐8, show enhancements at polar latitudes by more than a factor of ten over mid and low latitude values. The enhancements are generally not symmetrical with either the north pole or the auroral oval. They are attributed in part to increases in the Meinel band emissions of OH, particularly as associated with a stratospheric warming event, and in part to increases in nitric oxide densities in the lower thermosphere.
Precipitation scavenging of aerosol particles
Authors: Slinn W. G. N.
Published: February 2008

Formulae are suggested for the approximate description of below‐ and in‐cloud precipitation scavenging of monodisperse aerosol particles.
Source location measurements of terrestrial kilometric radiation obtained from lunar orbit
Authors: Kaiser M. L. , Alexander J. K.
Published: February 2008

Two‐dimensional source locations of individual terrestrial kilometric radiation (TKR) events have been measured by the Radio Astronomy Explorer‐2 (RAE‐2) spacecraft in lunar orbit. Although the average source location at 250 kHz is above the polar regions near the Earth (r ∼ 2‐3 RE), approximately 10% of the events occur at > 7 RE from the Earth. Furthermore, there is considerable evidence for multiple sources and source motion over the time scale of tens of minutes. Recent TKR mechanism theories which assume that the emission occurs at or near the local electron plasma or gyrofrequency would predict generation much closer to the Earth's surface. We therefore suggest that alternative emission mechanisms or special propagation conditions are required to explain many TKR events.
The radial variation of solar flare proton anisotropies observed in deep space on Pioneers 10 and 11
Authors: McCarthy J. , O'Gallagher J. J.
Published: February 2008

The anisotropy of solar flare protons (>3 MeV) evaluated at the time of maximum for each of 24 events measured by the University of Chicago experiments on Pioneers 10 and 11 is observed to decrease gradually between 1 and 4.7 a.u. Since diffusive streaming is related directly to the effective diffusion coefficient parallel to the interplanetary spiral magnetic field (K∥), these observations provide a measure of the radial dependence of interplanetary diffusion parameters. An analysis of these results suggests that K∥ increases gradually with r consistent with a radial dependence given by K∥ (r) = (8±3) × 1021 cm²/sec r0.9±.4 (r in a.u.).
Multiple Doppler radar observations of storms
Authors: Ray Peter S. , Wagner Kit K.
Published: February 2008

The use of radar to infer dynamical structure from storms is currently being extended by several research groups by employing two or more coherent radars positioned to allow construction of the three‐dimensional wind field. A simplified analysis implication for experiments using more than two Doppler radars is discussed. Optimum placement of a three‐radar network, based on a design criterion which minimizes the resolvable scale determined within a specified accuracy, is also given.
Traveling neutral disturbances
Authors: Gross S. H. , Eun H.
Published: February 2008

The coupling of acoustic‐gravity waves in the main atmosphere to acoustic waves characteristic of individual minor species in the atmosphere is postulated. Such coupling would exist as a result of resonances in the response of the minor species and its likelihood depends on the mass of the atmospheric particle relative to the major species mass, the diffusion of the minor species and the direction of propagation of the main disturbance. These minor species disturbances may explain some AE‐C measurements in the thermosphere, and could possibly play a role in the distribution of minor species and their chemistry in the mesosphere.
Parametric decay of whistlers – A possible source of precursors
Authors: Reeve C. D. , Boswell R. W.
Published: February 2008

Laboratory plasma experiments show that, above a certain threshold field strength, a whistler‐mode wave (WMW) may decay parametrically into a backward propagating WMW and a low frequency ion‐acoustic wave. The required threshold field for a 2 kHz wave in the equatorial plane of the magnetosphere, just inside the plasmapause, is found to be well below 1 mVm−1. It is suggested that the resulting backward travelling WMW may be responsible for triggering precursors ‐ rising frequency emissions which are occasionally observed to precede 2 (or more) hop whistlers.
Echo III: The study of electric and magnetic fields with conjugate echoes from artificial electron beams injected into the auroral zone ionosphere
Authors: Hendrickson R. A. , Winckler J. R. , Arnoldy R. L.
Published: February 2008

The third in a series of rocket flights carrying large electron guns for electron beam‐plasma analysis and magnetosphere probing has been carried out from the Poker Flat rocket range near Fairbanks, Alaska at L=6. Echoes from the injected electrons mirroring at the southern hemisphere conjugate point were observed on the rocket by particle detectors and in the nearby ionosphere by photometers on board the rocket. The bounce time and drift velocities of the echoes were measured using the known trajectory and aspect of the rocket. Ionospheric electric fields near the rocket were inferred from drift motion of the ambient ion population measured by two techniques, electrostatic analyzers on board the rocket and incoherent backscatter radar from the ground. Using model magnetic fields, gradient and curvature drift and bounce times have been computed under the conditions appropriate for this experiment. Assuming that field lines are equipotentials, the addition of the observed ionospheric electric field drift to the model‐dependent gradient and curvature drift predicts a net echo drift velocity that is in agreement with the observations, provided the Mead‐Fairfield 1972‐73 model is used. The observed bounce time constitutes an independent model check and is in better agreement with the Olson‐Pfitzer model. Echo spatial and temporal fluctuations reflected the turbulence associated with the diffuse aurora into which the rocket was launched.
The nature of electric field in E‐Region close to morning and evening reversals
Authors: Prakash S. , Muralikrisha P.
Published: February 2008

The nature of electrostatic field driving the equatorial electrojet was studied using a coherent backscatter radar at Thumba. The doppler spectra of radar echoes from ionization irregularities in the E‐region, during periods close to the morning and the evening electrojet reversals, show that the electric field, in general, is stronger during the pre‐reversal periods than during the post‐reversal periods. Similar results for the evening hours were reported earlier from the radar studies conducted at Jicamarca. This indicates that this effect is likely to be present at all the equatorial stations.
Field measurements of apparent Curie temperatures in a cooling basaltic lava lake, Kilauea Iki, Hawaii
Authors: Zablocki Charles J. , Tilling Robert I.
Published: February 2008

Magnetic susceptibility and temperature measurements have been made in two of three holes drilled in 1975 through the crust and into the still molten lens of tholeiitic basalt in Kilauea Iki lava lake (formed in 1959). The temperature above which magnetic susceptibility drops to zero—the apparent Curie temperature—is 540°C. at depths of 34.7‐35.9 m below the lake surface. These field measurements suggest that the dominant ferromagnetic mineral in the cooling basalt is titanomagnetite containing about 10 mol percent ulvöspinel.
The effect of pressure on the physics and chemistry of potassium
Authors: Bukowinski M. S. T.
Published: February 2008

The equation of state and electronic structure of body‐centered cubic potassium are investigated theoretically by the quantum‐mechanical SAPW method. The results predict a series of pressure‐induced electronic phase changes brought about by the sequential filling of initially unoccupied d‐like electronic states. In addition to the discontinuous density changes that accompany these phase transitions, the presence of the d‐like bands makes potassium extremely compressible. At pressures as low as 500 kb (0°K), the ionic radius of potassium becomes compatible with that of iron and its electronic structure becomes like that of a typical transition metal. These properties should greatly enhance the miscibility of potassium in iron or iron‐sulfide melts.
Effects of gravity wave winds and wind shears on equatorial electrojet
Authors: Anandarao B. G.
Published: February 2008

The equations governing the equatorial electrojet are solved with the inclusion of winds due to gravity waves and observed winds in the day‐time. It is shown that the gravity wave winds modulate the electrojet significantly in the region 110‐150 km even at the dip‐equator. The results show that the stronger the wind shear, the more will be its effect on the electrojet. The local contribution of observed winds to the electrojet as reported by Rees et al (1975) seems to be an over‐estimate.
Laboratory microwave spectrum of ClONO 2 and evidence for the existence of ClONO
Authors: Suenram R. D. , Johnson D. R. , Glasgow L. C. , Meakin P. Z.
Published: February 2008

The microwave spectrum of ClONO 2 has been analyzed in the laboratory under high resolution. Rotational constants are reported for the ground and lowest vibrational states of the 35Cl and 37Cl isotopic forms. From Stark effect measurements the electric dipole moment was found to have components along two principal axes, μ a = 0.72 ± 0.10 Debye and μ b = 0.28 ± .04 Debye. Difficulties encountered in handling gas phase samples of ClONO 2 are discussed in some detail and evidence is presented for the existence of a closely related chlorine containing compounds which is believed to be ClONO. This second compound may also prove to be important in detailed atmospheric modeling. The rotational constants for ClONO are also given.
Density and surface wave inversion
Authors: Burkhard Norman R. , Jackson David D.
Published: February 2008

A useful measure of the importance of a given parameter in an inverse problem is the standardized partial derivative, which is scaled by the a priori uncertainty of the parameter in question. Because the density distribution in the upper mantle is poorly known, the a priori uncertainty for density is rather large; thus density must generally be considered as a variable in the inversion of surface wave phase velocity data.
Atmospheric ice nuclei: No detectable effects from a coal‐fired powerplant plume
Authors: Schnell R. C. , Van Valin C. C. , Pueschel R. F.
Published: February 2008

Atmospheric ice nuclei were measured upwind and within the effluent plume of a coal‐fired powerplant during February 1976. Aerosol particles were captured on two types of membrane filters (Nuclepore and Millipore) and processed in two different thermal diffusion chambers, one calibrated to produce a 100% saturation relative to water and the other to produce a slight supersaturation relative to water. Consequently, the ice nuclei measured were active in the modes that are dominant in diffusion chambers, viz., deposition nucleation and condensation‐followed‐by‐freezing nucleation. Results indicate that plume particles do not act as ice nuclei between the temperatures of −10 and −20°C, nor do combustion gases in the plume deactivate natural ice nuclei.
In situ measurements of neon in the thermosphere
Authors: Potter W. E. , Kayser D. C.
Published: February 2008

The open source neutral mass spectrometer (OSS) on the Atmosphere Explorer‐C satellite has measured neon in the thermosphere. The absolute density of Ne is close to that predicted by using the ground level fraction by volume of Ne along with the assumption of diffusive equilibrium above 100 km. Data is presented for both geomagnetically quiet and disturbed circular orbits. At 290 km, a typical low latitude value of [Ne] is 3.0 × 104 cm‐3. At this altitude Ne appears to be predominantly controlled by temperature except during magnetic disturbances, when offsetting forces due to wind systems may be present.
Radar profiles of the equatorial electrojet
Authors: Crochet M. , Poman C. , Hanuise C.
Published: February 2008

The electrojet current deduced from radar measurements was found in the past to present large E‐W variations near the coast of Peru. New measurements in Africa indicate that the electrojet shows no anomalous variations with longitude in Central Africa while a large E‐W asymmetry is detected in East Africa near the Red Sea. Local structures of the magnetic field and particularly the non‐perpendicularity of the field lines to the dip equator can be at the origin of a permanent asymmetry. The origin of the enhancement of the asymmetry during magnetic disturbances is still unclear but can be associated partly to neutral wind gradients and possibly to induced effects related to large variations of the earth conductivity in East Africa.
Dependence of the charge exchange lifetimes on mirror latitude
Authors: Smith Paul H. , Bewtra N. K.
Published: February 2008

The dependence of the charge exchange lifetimes on the mirror latitude for ions mirroring off the geomagnetic equator has been re‐computed using the improved hydrogen distribution models which have become available since the earlier calculation by Liemohn. The Chamberlain model, with the input parameters determined by recent satellite observations, has been used to define the spatial distribution of the neutral hydrogen environment through which the ring current ions traverse. The resultant dependence of the charge exchange lifetime, τ, on mirror latitude, λm, is best fit by the approximation τm = τe cos3.5λm, where τe is the charge exchange lifetime for the equatorial particles. This is a significant change from the cos6λm approximation of the previous results.
Composition effects in thermospheric gravity waves
Authors: Dudis Joseph J. , Reber Carl A.
Published: February 2008

Classical linearized gravity wave theory is employed to derive relationships between amplitude ratios and phase angles of atmospheric constituents undergoing acoustic‐gravity wave oscillations. These results are compared with recently reported Atmospheric Explorer‐C satellite data. Calculated amplitude and phase characteristics, for a large class of pure internal gravity wave oscillations, are in accord with the AE‐C satellite measurements.
Variations in eddy diffusion and associated transport processes
Authors: Mayr H. G. , Harris I.
Published: February 2008

Variation in the eddy diffusion coefficient near the turbopause affects not only the composition but also the wind and temperature fields of the thermosphere. Composition and wind fields are strongly coupled such that for long term (annual) variations the eddy diffusion effects are entirely different in one and three dimensional models. Horizontal winds, driven by the oxygen bulge which in turn is induced by eddy diffusion, act as a feedback to significantly reduce the composition variations in general and the ratio between He and O amplitudes in particular. The resulting He amplitude from three dimensional calculations is by about a factor of ten lower than the O amplitude above 150 km, in striking contrast to composition data. Due to temperature variations, isopycnic levels develop at 250 km (He) and 450 km (O), such that at higher altitudes both species vary in phase with the eddy diffusion coefficient. The eddy diffusion mechanism must thus be excluded as a principle candidate for describing the spherical asymmetries in the annual variation of the thermosphere. The temperature increase associated with adiabatie heating from the wind component can be substantial; turbulent energy is thereby effectively transported from the mesosphere up into the thermosphere.