bluuebunny/crossref_metadata_2025 huggingface dataset:
Ratios of dry to wet deposition of sulfur as derived from preliminary field data
Authors: Hicks B. B. , Meyers T. P. , Fairall C. W. , Mohnen V. A. , Dolske D. A.
Published: February 2008

Preliminary data obtained in the operation of a nested‐network dry deposition measurement program in the eastern United States are used in conjunction with wet deposition data obtained at (or near) the same sites to investigate the variability of ratios of dry to wet deposition of sulfur (as sulfur dioxide and submicron sulfate for dry deposition, and as sulfate for wet deposition). On a monthly basis, the ratio is extremely variable at every location; however, a more coherent picture arises when the average annual cycle is considered. The sites studied here (Oak Ridge, Tennessee; State College, Pennsylvania; Whiteface Mountain, New York; and Bondville, Illinois) yield dry/wet ratios for sulfur deposition that minimize in the summer, with values of about 0.3. At other times of the year, values sometimes exceeding 2.0 are obtained. A summer peak at Oak Ridge is tentatively attributed to the effects of a local drought. The variability is such that use of dry/wet ratios to estimate dry deposition rates when only wet deposition data are available cannot be recommended.
Spatial and temporal variations of methane flux from subarctic/northern boreal fens
Authors: Moore Tim , Roulet Nigel , Knowles Roger
Published: February 2008

Emissions of CH4 were measured by a static chamber technique (five chambers/site) at 23 sites in four fens near Schefferville, subarctic Quebec. At three intensively‐monitored sites along a transect from fen margin to central and flooded sites, mean CH4 fluxes from June to August, 1989 were 65, 125, and 36 mg m−2 d−1, respectively. Pore water CH4 concentrations in the peat profiles to a depth of l m averaged 125 to 200 μM, with lower concentrations (generally <50 μM) at 0.1 m. Total, depth‐integrated storage of CH4 in the peat profiles ranged from 3.5 to 4.3 g m−2. Although CH4 flux was only weakly correlated with either peat temperature at 0.1 m or water table position within each site, there was a strong association of flux and these variables among the three sites, indicating the value of ecological attributes in identifying patterns of CH4 flux. A pulse of CH4 was recorded at two of the three sites in mid‐August, associated with a degassing of the peat profile, based on pore water CH4 concentrations. This pulse appeared to be initiated by the lowering of the water table by between 5 and 10 cm during a 3‐week period of low rainfall and is estimated to have contributed 18 to 65% of the seasonal CH4 emission, depending on the location of the site. An estimate of the regional CH4 flux from 130 km2 of the Schefferville area was based on CH4 flux measurements at 23 sites in the area, stratified by fen type (forested margin, margin, central, flooded, ridge, and pool). June to August regional CH4 flux was 18 mg m−2 d−1, for an area in which fen coverage was 29%. When extrapolated to the global scale, these results indicate that northern fens may contribute about 14 Tg yr−1, somewhat lower than other recent estimates.
Peroxyacetyl nitrate in the North Atlantic marine boundary layer
Authors: Gallagher Michael S. , Carsey Thomas P. , Farmer Michael L.
Published: February 2008

An automated system utilizing packed column gas chromatography and electron capture detection for the determination of peroxyacetyl nitrate (PAN) is described. The system was calibrated with a cryogenic PAN sublimation device, a molybdenum catalyst, and a chemiluminescent nitric oxide detector. Computer control of the analysis resulted in an analytical precision level of ∼1%. A total of 1178 PAN measurements were made from August 6 to September 5, 1988, in the marine boundary layer during the GCE/CASE/WATOX cruise (66°N to 7°N). Overall, PAN concentrations were highest at high latitudes (up to 40 ppt); PAN levels in the lower latitudes of the cruise track were usually <10 ppt. A number of episodes of elevated PAN are described which were characterized by elevated radon concentrations and a discernible diurnal cycle in the PAN concentration. These higher PAN levels are attributed to air masses with some continental influence, and to the enhanced stability of PAN at the cooler temperatures characteristic of the sub‐Arctic region. In aged air masses of marine origin, PAN concentrations were significantly less and did not display diel changes; this is interpreted as a measure of the “background” PAN signal.
Measurements of solar wind helium in the lunar atmosphere
Authors: Hodges R. R. , Hoffman J. H.
Published: February 2008

Measurements of lunar atmospheric helium during 1973 from the Apollo 17 lunar surface mass spectrometer are presented. The average helium abundance is shown to be about 70% of the theoretical model value, suggesting that the solar wind helium flux in 1973, during sunspot minimum, was substantially less than the expected average flux. Large amplitude transients in the helium data indicate rapid response of the lunar atmosphere to changes in solar wind. The atmospheric helium abundance is shown to be correlated with the geomagnetic index Kp.
The horizontal coherence of inertial oscillations in a coastal region
Authors: Kindle John C.
Published: February 2008

The horizontal coherence of inertial oscillations was investigated using the records from six current meters moored on the Oregon continental shelf and whose separation distance varied from approximately 9 to 35 km. The rotary component method for analyzing vector time series was used to form the cross spectra and coherencies for 15 pairs of records, the length of which varied from 10 to 27 days. The velocity field was found to be highly coherent for periods greater than about 10 days. The coherencies at the inertial frequency, which were generally quite low, could be accounted for (with some exceptions) by a consideration of both the separation distance and a simple representation of the effects of stratification.
Internal wave‐turbulence interpretation of ocean fine structure
Authors: Bell T. H.
Published: February 2008

The observed shape of vertical spectra of ocean temperature fluctuations is shown to be consistent with an interpretation of deep ocean fine structure in which fluctuations with vertical wavenumbers less than about one cycle per meter are identified with internal wave motions while those with wavenumbers greater than a cycle per meter are identified with small scale turbulence.
Stacking marine magnetic anomalies: A critique
Authors: Parker Robert L.
Published: February 2008

It is shown that the procedure of summing (stacking) together a number of surface magnetic anomaly records does not significantly improve the ultimate resolution of short events in the geomagnetic polarity sequence. The limit of resolution (shown elsewhere to be about 3 km for surface data) is determined by the presence of signals not originating in the crust. Single profiles will not usually attain this optimal resolution, however, because of geological irregularities in the magnetic layer. Therefore, stacking offers improvement at longer wavelengths, but not all unwanted effects are properly suppressed: for example, (a) bathymetric features can cause coherent signals in closely spaced surveys and stacking will amplify them; (b) the stacking of phase‐shifted anomalies causes smoothing rather than sharpening of transitions.
On ocean current induced by a prograding ice pack
Authors: Neshyba S. , Badan‐Dangon A.
Published: February 2008

An ice cover which progrades over a shallow ocean may induce a baroclinic flow in the underlying water, providing that the brine excluded from the freezing surface layer is mixed rapidly through out the underlying water column. For a simplified model of the shallow northern part of the Bering Sea the near‐surface flow rate is of the order of 2 cm sec−1and directed to the east. Volume transport, assuming a nominal depth of 100 m, is about 0.1 Sverdrup. Over a 3 month freezing period up to 800 km³ are transported through a given meridional section of this model. One might conclude that the process may play a significant role in winter circulation in the Bering Sea.
Static deformation of the Earth's liquid core
Authors: Crossley D. J. , Gubbins David
Published: February 2008

There has been some recent controversy over the precise nature of the conditions to be imposed at the core‐mantle boundary when the Earth suffers a static deformation. We here define static deformation by requiring the fluid core to be in hydrostatic equilibrium both before and after the deformation, and then show how to determine the fluid response in terms of the gravitational potential and normal stress, without reference to particle displacement. The core‐mantle boundary is modelled by a thin transition layer between the solid and the fluid in which the rigidity drops to zero. A careful examination of the jump conditions across the transition layer leads to the conclusion that the variables y1, y2 and y6 as defined in the solid are all discontinuous.
A teleseismic array study in French Polynesia; Implications for distant and local structure
Authors: Okal Emile , Kuster Guy
Published: February 2008

We analyze slowness and azimuth anomalies, as recorded in the French Polynesia Seismic Network. The network can be considered as an array in its whole, or can be split into two subarrays, 350 km apart. In the former case, it is found that, contrary to Canadian VASA results, no anomaly is apparent for rays bottoming under Hawaii. In the latter case, a model of the crust is attempted under Tahiti as well as under the atoll of Rangiroa.
On the air drag of an Arctic Ice Floe
Authors: Langleben M. P. , Pounder E. R.
Published: February 2008

Measurements of wind speed were made between 31 March and 12 April, 1972 with sensitive cup anemometers at five heights in geometric progression from 25 cm to 4 m above the surface of a gently hummocked ice floe at each of two observation masts which were placed 250 m apart at the site of the main camp of the 1972 AIDJEX pilot experiments. The data were averaged for one‐hour periods and have been used to determine the air drag coefficient on the 64 occasions when the vertical profile of wind varied logarithmically with height and to study the horizontal homogeneity of the wind field in the boundary layer. Mean values of the drag coefficient, for winds extrapolated to the 10 m level, were 1.58 × 10−3 at one location with a standard deviation for an individual value of 0.19 × 10−3 and 1.74 × 10−3 ± 0.25 × 10−3 at the other. The corresponding values of roughness length zo were 0.043 and 0.069 cm.
Beam‐plasma interactions as a heat source in the magnetosphere
Authors: Fontheim Ernest G.
Published: February 2008

Strong electron precipitation fluxes are frequently accompanied by strong downward heat conduction fluxes, deduced from simultaneous high and low altitude electron temperature measurements. It is shown that the heat input due to beam‐plasma interactions is of the correct order of magnitude to sustain the observed heat flux.
An over‐the‐horizon radio direction‐finding system for tracking coastal and shelf currents
Authors: Murray Stephen P. , Roberts Harry H. , Wiseman Wm. J. , Tornatore H. Gregory , Whelan William T.
Published: February 2008

A new direction‐finding system is capable of tracking, from coastal stations, the drift of drogues more than 100 km from the shoreline. Frequency‐dependent transmitters on light, inexpensive drogues permit as many as fifteen widespread drogues to be monitored quasi‐simultaneously, enabling researchers to obtain mesoscale synoptic data at reasonable cost for the first time. Field tests on a moored drogue in Chesapeake Bay and on free‐drifting drogues at sea off Barbados show the system to be reliable and accurate.
In situ measurements of plasma drift velocity and enhanced NO+ in the auroral electrojet by the Bennett Spectrometer on AE‐C
Authors: Brinton Henry C.
Published: February 2008

Simultaneous measurements of ion composition and plasma drift velocity by the Bennett mass spectrometer on the Atmosphere Explorer‐C satellite reveal a direct correlation between enhancements in NO+ concentration and ion drift velocity in the southern auroral oval. Low altitude (137 to 250km) data obtained between 1700 and 2400 hr magnetic local time on October 22, 1974 reveal a region of westward plasma flow at velocities up to 1.3km/s between 62° and 68° invariant latitude, with corresponding NO+ enhancements of up to a factor of 20. A narrow region of reverse flow at ∼0.9km/s was also measured. These drift observations are consistent with convective flow patterns derived from electric field measurements, and their correlation with NO+ appears to support the suggestion that NO+ enhancements would be expected in regions of drift owing to the dependence on ion energy of the reaction O+ + N2 → NO+ + N.
Using the Moon to probe the geomagnetic tail lobe plasma
Authors: Schubert G. , Sonett C. P. , Smith B. F. , Schwartz K. , Colburn D. S.
Published: February 2008

We have detected the presence of plasma in the lobes of the geomagnetic tail from observations of magnetic induction in the Moon forced by time variations of the Earth's magnetotail lobe field. The magnitude of the Moon's tangential electromagnetic transfer function when the Moon is in the lobes of the geomagnetic tail is less than that when the Moon is in the solar wind or geomagnetic tail plasma sheet. The tangential transfer function when the Moon is in the magnetotail lobes decreases at frequencies above about 8 milliHz due to finite wavelength effects. This shows that the waves in the magnetotail lobes which drive the lunar magnetic induction must have speeds far less than the speed of light and wavelengths comparable to the size of the Moon.
On the formation of the outflow through the Strait of Gibraltar
Authors: Roether W. , Weiss W.
Published: February 2008

From the tritium to salinity relationship on stations occupied in early 1974 on both sides of the Strait of Gibraltar, a mean tritium concentration of 1.6 ± 0.2 TU (1 sigma) is derived for the original Mediterranean water that feeds the outflow. The same tritium concentration is observed in the Mediterranean near to the Strait (Alboran Sea) in about 700 m depth. The layers shallower than about 450 m have so much higher tritium concentration that it can be concluded that they contribute only a small fraction of the outflow.
The vertical distribution of soluble gases in the troposphere
Authors: Stedman D. H. , Chameides W. L. , Cicerone R. J.
Published: February 2008

The thermodynamic properties of several water‐soluble gases are reviewed to determine the likely effect of the atmospheric water cycle on their vertical profiles. We find that gaseous HCl, HNO3, and HBr are sufficiently soluble in water to suggest that their vertical profiles in the troposphere have a similar shape to that of water vapor. Thus we predict that HCl, HNO3, and HBr exhibit a steep negative gradient with altitude roughly equal to the altitude gradient of water vapor. Therefore, ground‐based sources of inorganic chlorine, odd nitrogen, and inorganic bromine compounds are not likely to directly affect the stratosphere in the mean. Calculations also show that while SO2 and NH3 are significantly affected by the atmospheric water cycle, their abundances may not decrease with altitude as rapidly as does water vapor.
On the anisotropies of interplanetary low‐energy proton intensities
Authors: Pesses M. E. , Sarris E. T.
Published: February 2008

Anisotropic fluxes of low‐energy protons deviating from the magnetic field direction by as much as 45° during periods of time that the magnetic field vector was along the sun‐earth line have been observed under certain conditions of the interplanetary medium.
Seismic energy transmission from ocean to continent in western South America
Authors: Ocola Leonidas C. , Gettrust Joseph F. , Meyer Robert P. , Woollard George P.
Published: February 2008

During the first part of 1973, two tests of seismic energy transmission from the Pacific oceanic shelf and adjacent plate to continent using controlled sources were carried out in dissimilar areas, one associated with Colombia and one associated with Peru. Results from both experiments show that the energy transmission as far inland as the eastern cordillera is surprisingly good, unlike our experience in the Andes shooting parallel to structure. Since the differences in the degree of tectonic activity and differences in structure inferred from geology, bathymetry, gravity and seismic natural event information for these two regions spans that found in western South America, it is believed that these results are sufficiently general to imply that the whole of western South America can be studied using ocean shot points.
The magnetospheric contribution to the quiet‐time low energy nucleon spectrum in the vicinity of Earth
Authors: Krimigis S. M. , Kohl J. W. , Armstrong T. P.
Published: February 2008

The upturn in the low energy quiet‐time interplanetary nucleon spectrum has previously been described as of galactic or solar origin. Recent observations have suggested that the magnetosphere may be an important source, at least at the lowest energies. Observations obtained with the JHU/APL experiment on Explorer 47 (IMP‐7) during the March 9–12, 1973 period show that the magnetosphere is the dominant contributor to the quiet time interplanetary proton population in the range 0.29 ≤ Ep ≤ 0.5 MeV, and suggest that it may be an important contributor up to energies of ∼1.5 MeV. The March 9–12 period is the quietest (on a time scale of hours) in a ∼ 2.5 year interval extending from September 72 through February 1975. The quiet‐time energy spectrum may be represented by a power law E−(3.1 ± 0.2), the H/He ratio at ≲ 2 MeV/nucleon is ∼ 10 and the He/Z ≥ 3 ratio at ∼ 1 MeV/nucleon is ∼ 8. The ratio of anti‐sunward to sunward intensities is ∼ 2.6 and increases to ∼ 8.55 in a frame moving with the solar wind, i.e., the maximum intensity is coming from the direction of the bow shock. The observed intensities are factors of 3 to 10 lower than those reported earlier by the Chicago group, suggesting that the interpretation of the low energy gradient measurement reported by those authors needs to be revised. It is speculated that the low energy (≲ 20 MeV) upturn in the quiet‐time interplanetary proton spectrum may be related to particle emissions from planetary magnetospheres, such as that of Jupiter.
Spectroscopic detection and vertical distribution of HCl in the troposphere and stratosphere
Authors: Farmer C. B. , Raper O. F. , Norton R. H.
Published: February 2008

HCl has been observed in both the troposphere and stratosphere from ground‐based and airborne spectroscopic measurements of the 1‐0 band at 3 microns wavelength. The results, which are specific to the HCl molecule in the gas phase, show a decreasing mixing ratio with altitude in the lower stratosphere. The stratospheric layer, which commences at about 15 km, reaches its maximum concentration at an altitude above 21 km (the limiting height of the observations to date). The local value for the volume mixing ratio at 21 km is 7 ± 1 × 10−10. However, the zenith column abundance observed above 21 km (6.3 × 1014 mols. cm−2) implies that the mixing ratios at greater altitudes are unlikely to reach values much in excess of the local value at 21 km.
Stratospheric HCl from infrared spectra
Authors: Ackerman M. , Frimout D. , Girard A. , Gottignies M. , Muller C.
Published: February 2008

HCl has been observed in the stratosphere from balloon borne spectroscopic measurements of a portion of the fundamental band in the 3 microns wavelength region. The observation of absorption lines using the sun as a source at solar zenith angles larger than 90° indicates an HCl volume mixing ratio equal to (3.8 ± 1.5) × 10−10 at 20 km increasing with altitude at least up to 30 km where the value is (1.4 ± 0.6) × 10−9. The total zenith amount above 21 km is found to be (10± 3.5) × 10−14 cm−2 in agreement with previous observations performed up to this altitude. A maximum number density equal to (7.2 ± 3) × 108 cm−3 is observed at 24 ± 2 km altitude.
Predominance of even Ap indices
Authors: Fraser‐Smith A. C. , Bubenik D. M.
Published: February 2008

A study of the frequency distribution of geomagnetic activity Ap indices shows that there is a tendency for more of the indices to be even than are odd. We identify the probable source of the bias, i.e., the use of a particular rounding rule in the derivation of the Ap values, and we suggest two methods for eliminating the tendency to even values.
Photodissociation of methyl chloride and methyl bromide in the atmosphere
Authors: Robbins Donald E.
Published: February 2008

Methyl chloride (CH3Cl) and methyl bromide (CH3Br) have been suggested to be significant sources of the stratospheric halogens. The breakup of these compounds in the stratosphere by photodissociation or reaction with OH releases halogen atoms which catalytically destroy ozone. Experimental results are presented for ultraviolet photoabsorption cross sections of CH3Cl and CH3Br. Calculations are presented of loss rates for the methyl halides due to photodissociation and reaction with OH and of mixing ratios of these species in the stratosphere.
On the modulation of whistler turbulence by magneto‐acoustic perturbations
Authors: Shukla Padma K. , Spatschek Karl H.
Published: February 2008

It is shown that a gas consisting of random‐phased high‐frequency whistler wave packets can become modulationally unstable with respect to low‐frequency magneto‐acoustic perturbations. The growth rate and threshold of the instability are calculated. The relevance of the instability to ULF emissions in the magnetosphere is discussed.
Whistler observations of the dynamical behavior of the plasmapause during June 17‐22, 1973
Authors: Park C. G. , Seely N. T.
Published: February 2008

The dynamical behavior of the plasmapause is studied using whistlers recorded at Siple, Antarctica (∼84°W, L ∼ 4) during June 17‐22, 1973. The magnetic activity during this period remained fairly disturbed until June 21, causing the plasmapause to contract to less than 3 earth radii (RE). Sudden quieting on June 22 caused the plasmasphere to develop complex outlying structures with the high density region extending out to about 6 RE. The plasma‐pause data show a repeated diurnal pattern of a relatively slow decrease in equatorial radius by ∼0.5‐1 RE during the night and a more rapid increase by about the same amount near dusk when the plasmasphere bulge is encountered. These data should provide a basis for detailed correlative studies of many plasmapause‐associated phenomena.
Detailed halocarbon measurements across the Alaskan tropopause
Authors: Robinson E. , Rasmussen R. , Krasnec J. , Pierotti D. , Jakubovic M.
Published: February 2008

Halocarbon concentrations were obtained from the upper troposphere and lower stratosphere over Alaska in May 1975 using aircraft sampling techniques and subsequent laboratory analysis. The data demonstrate two phenomena: (1) a rapid decrease in the halocarbon concentrations across the tropopause into the lower stratosphere, and (2) variable day‐to‐day concentration gradients either decreasing or increasing upward from the tropopause depending upon meteorological conditions. An air mass transport mechanism through the tropopause into the stratosphere is proposed to explain the temporal and spatial variations observed.
Electrokinetic phenomena associated with earthquakes
Authors: Mizutani H. , Ishido T. , Yokokura T. , Ohnishi S.
Published: February 2008

Electrokinetic phenomena induced by ground water flow associated with earthquakes are proposed to provide a possible means of earthquake prediction. Detectable variations of earth currents, electric potential and geomagnetic field may be caused by diffusion of fluid into a dilatant focal region. The principle of electrokinetic phenomena may be used for earthquake control by controlling the water flow with an artificial electric potential field.
Variation of compressional velocities in simulated fault gouge under normal and direct shear stress
Authors: Peselnick L. , Dieterich J. H. , Mjachkin V. I. , Sobolev G. A.
Published: February 2008

An experimental method designed to measure ultrasonic velocities in simulated fault gouge subjected to normal and direct shearing stress yields these results. For a well‐compacted, unsorted, fine‐grained, dry granite gouge under constant normal stress, reversible changes in Vp with shear stress are observed prior to stable sliding. Vp decreases by as much as 9% with increasing shear stress for the conditions of these experiments. For layers of intact granite slabs subjected to constant normal stress, and whose interfaces are relatively free of gouge material, Vp increases with increasing shear stress. The observed velocity changes in the granite gouge experiments are believed to be produced by reversible opening and closing of small cracks. For a gouge material consisting of moderately compacted, sorted, coarser‐grained, dry sand, irreversible changes in Vp were observed. The predominant changes in Vp for the sand gouge are believed to result from grain fracturing and from readjustment of grains to a denser state of aggregation with changes in the general stress.
On the utility of radiogenic heat measurements for uranium exploration
Authors: Mogro‐Campero A. , Fleischer R. L.
Published: February 2008

A simple model of heat propagation from a buried radioactive deposit is presented and used to evaluate the possibility of interpreting heat flux and temperature measurements as guides in prospecting for uranium. Using parameters from large known uranium deposits, it is concluded that unless the product of ore grade times thickness of the deposit considerably exceeds the largest values known to us at present, the search for elevated heat fluxes and temperatures is not a useful prospecting technique.
Local time variation of induction vectors as indicators of internal and external current systems
Authors: Anderson C. W. , Lanzerotti L. J. , Maclennan C. G.
Published: February 2008

We have observed significant temporal variations in the local time dependence of geomagnetic induction vectors calculated at two‐hour intervals for twelve days at four latitudinally‐spaced stations near L = 4. The present results and discussion call into some question the assumptions commonly made in the straightforward derivation and use of such induction vectors for defining internal conductivity structures.
Preliminary results of stratospheric SO2‐measurements
Authors: Jaeschke W. , Schmitt R. , Georgii H.‐W.
Published: February 2008

The development of a new analytical technique to detect SO2 in the ppb‐range permits the measurement of SO2 in the upper troposphere and the lower stratosphere. First results of aircraft‐ascents are presented showing SO2‐concentrations of 145 ng SO2/m³ STP for 13 km altitude.
Southern hemisphere mid‐latitude stratospheric aerosol after the 1974 Fuego Eruption
Authors: Gras J. L.
Published: February 2008

A time series of aerosol concentration profiles for the lower stratosphere was obtained at 34° S. (Mildura, Australia) during the 12 months after the eruption of Fuego volcano in Guatemala in October 1974. A persistent thin aerosol‐rich layer was found at or near 17 km; it existed from late 1974 and was replenished in the southern winter of 1975. The available evidence indicates that the initial layer was probably not due to the Fuego eruption.
On the rotational bursting of interplanetary dust particles
Authors: Misconi N. Y.
Published: February 2008

A model of the zodiacal cloud is used to evaluate the effects of rotational bursting on interplanetary dust particles caused by the interaction of solar radiation pressure with the irregular surface geometry of the particles. The effectiveness of this mechanism is evaluated using several values for the effective moment arm and tensile strength of the particles. Due to repeated bursting, it is shown that particles spiraling in from the asteroid belt by the Poynting‐Robertson effect do not penetrate inside 1.2 A.U. Spin rate stabilization under the effect of magnetic damping is found to depend critically on the initial heliocentric distance of the particle and on its radius.
Quasi‐biennial geomagnetic variation caused by the Sun
Authors: Sugiura Masahisa
Published: February 2008

Clear evidence for the existence of a quasi‐biennial geomagnetic variation is shown by an analysis of annual averages of the horizontal (H) component of the geomagnetic field observed at five observatories. The analysis uses a numerical filter, which is equivalent to taking the second order time derivative of the time series. The cause for the variation is external to the earth because its amplitude depends on magnetic activity. The second order time derivative of H is well correlated with the corresponding time derivatives of the relative sunspot number and 10.7 cm solar flux. It is suggested that quasi‐biennial oscillations observed in the geomagnetic field, cosmic rays, stratospheric zonal wind and temperature, total ozone, and other meteorological parameters could be produced by a common cause on the sun.
Elastic dilatancy, fluid saturation, and earthquake dynamics
Authors: White J. E.
Published: February 2008

The mathematical description of fluid‐saturated rocks developed by Biot and others has been applied to earthquake dynamics, providing a quantitative relation between rock properties and some seismic precursors which are being widely evaluated as a basis for earthquake prediction. This relation is a quantitative expression of the dilatancy‐diffusion model of earthquake dynamics, with one significant refinement in concept: the dilatancy here is a consequence of the nonlinear stress‐strain curve for rocks, rather than a result of crack formation as the rock approaches failure. Solution gas plays a key role. The computed imbalance in fluid pressure following the stress‐release by an earthquake provides a starting point for describing the time sequence and spatial migration of aftershocks.
Correction [to “Laboratory microwave spectrum of ClONO2 and evidence for the existence of ClQNO”]
Authors: Suenram R. D. , Johnson D. R. , Glasgow L. C. , Meakin P. Z.
Published: February 2008

The microwave spectrum of ClONO2 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, μa = 0.72 ± 0.10 Debye and μb = 0.28 ± 0.04 Debye. Difficulties encountered in handling gas phase samples of ClONO2 are discussed in some detail.
Esro 4 model of global thermospheric composition and temperatures during times of low solar activity
Authors: von Zahn U. , Köhnlein W. , Fricke K. H. , Laux U. , Trinks H. , Volland H.
Published: February 2008

We present an empirical model of global exospheric temperatures and densities of neutral constituents, based on data from 228 geomagnetically quiet days during the operation of the Esro 4 gas analyzer (mean Ap = 7). By means of an expansion in spherical harmonics the model infers exospheric temperatures from both the measured N2 and Ar densities. O and He densities are presented as extrapolated density distributions at 120 km altitude. The Esro 4 model complements the similar Ogo 6 mass spectrometer model with observations at considerably lower altitudes (240‐320 km) and lower levels of solar activity
Inferred exospheric temperatures are typically 5‐9% below Ogo 6 model values for F10.7 = 120.
Evaluation of Jupiter longitudes in System III (1965)
Authors: Seidelmann P. K. , Divine Neil
Published: February 2008

Commission 40 of the International Astronomical Union has adopted a new longitude system for Jupiter, labelled System III(1965), to replace the provisional System III(1957.0). The specification of the prime meridian and epoch for the new system differs slightly from that recently published. Its rotation rate implies a period of 9h55m29s.711 ±0s.04, consistent with recent determinations from decimetric and decametric data. For both the new and older systems, equations are provided which are useful in the evaluation of longitudes for the analysis of Jupiter radio, particle and field data from Earth and spacecraft observations.
Seismicity of northeast Alaska
Authors: Gedney L. , Biswas N. , Huang P. , Estes S. , Pearson C.
Published: February 2008

During the Fall and Spring of 1975/76, nine telemetered seismographic stations were emplaced in the Brooks Range in northeast Alaska. This is an area not previously instrumented, and the historic record indicates a very low incidence of earthquakes in this part of Alaska. During a one year recording period, data from the new network permitted the location of 69 earthquakes in the magnitude 1‐4 range. This was accomplished in spite of a high incidence of station outages which considerably reduced the usable data collected during the study period. Results of this study suggest that the usual concept of low seismicity levels in northeastern Alaska should be reevaluated.
Very low‐Ti mare basalts
Authors: Taylor G. Jeffrey , Keil Klaus , Warner Richard D.
Published: February 2008

Bulk compositions, petrology, and mineralogy of lithic fragments discovered in polished sections of Apollo 17 drill core samples 70007, 70008, and 70009 and Luna 24 soil 24077, 43 are described. The fragments have unambiguous affinities to mare basalts, but are exceptionally low in TiO2 (<1.0 wt.% TiO2). Apollo 17 rake sample 78526 is a green glassy rock of similar composition. Together the samples represent a distinct variety of mare basalts. Bulk compositional relationships suggest that they are related to Apollo 15 green glass, but the data do not permit us to discern the precise nature of the relationship. Both fractional crystallization and partial melting models can explain the observed compositional trends.
Longitudinal variations of very‐low‐frequency chorus activity in the magnetosphere: Evidence of excitation by electrical power transmission lines
Authors: Luette J. P. , Park C. G. , Helliwell R. A.
Published: February 2008

Very‐low‐frequency (VLF) chorus activity detected by the Ogo 3 satellite has the highest probability of occurrence in regions threaded by geomagnetic field lines that intersect industrialized areas. Interpretation of these results is based on radiated power line harmonics that leak into the magnetosphere and stimulate the recorded emissions through cyclotron interaction with trapped energetic electrons. These results emphasize the need for a careful evaluation of the effects of man‐made VLF noise on the ionosphere and magnetosphere.
Empirical eigenvector analysis of vector observations
Authors: Hardy Donald M.
Published: February 2008

A method of deriving an empirical eigenvector or principal components representation of wind velocity measurements is given. The mathematical basis for generalizing the empirical eigenvector method to the treatment of vector data fields is stated briefly. The method presented can be employed in the analysis of regional wind velocity patterns. Applications of the analysis technique to other geophysical vector fields are also possible.
Upper mantle velocities under the East Coast Margin of the U.S.
Authors: Lewis Brian T. R. , Meyer R. P.
Published: February 2008

Travel times from the East Coast Onshore‐Offshore Experiment suggest that the P velocity of the upper mantle under the margin of the east coast may be constant or decrease slightly with depth down to about 70 km where there is a rapid increase in velocity to about 8.5 to 8.6 km/sec.
Doppler shifts on whistler mode signals received at Siple Station, Antarctica
Authors: Andrews M. K. , Thomson N. R.
Published: February 2008

A VLF receiver at Siple Station during 1975 recorded the Doppler shift on Whistler mode signals from NAA, Cutler, Maine. An initial analysis of the data shows that signals could be received at any hour of the day during Southern Winter. On the dayside, the Doppler shift frequently showed large oscillations, due to pulsations in the Pc4‐5 range. On average, a well‐defined diurnal pattern of shifts was found. This pattern supports some features of recent measurements of the convection electric field in the plasmasphere, and also suggests that the quiet plasmasphere near L = 3 refills by ∼1017el/m²/day for the entire tube between the 1000 km levels.
Preliminary analysis of microacoustic signals associated with rock fracture
Authors: Blacic J. D. , Malone S. D.
Published: February 2008

A new experimental rock deformation system utilizing a piston‐cylinder apparatus allows recording of microacoustic signals associated with rock failure with great accuracy over a bandwidth of DC‐4MHz. A calibrated response makes possible the measurement of dynamic seismic parameters which may be compared with those predicted by theory. Preliminary analysis of two events generated during brittle shear failure of granite suggests that the strain drop of ∼1 × 10−4 is similar to that of large earthquakes. A seismic moment of 106 dyn‐cm and corner frequency of 600 KHz are consistent, in a general way, with those expected from theory.
The photochemical role of tropospheric nitrogen oxides
Authors: Chameides W. L.
Published: February 2008

The role of nitrogen oxides in the tropospheric photochemical system is re‐evaluated in the light of recent measurements of the rate constants for two key reactions. A model for nitrogen oxides is discussed which yields surface NO x (NO+NO 2 ) levels approaching 1 ppb in NO x source regions but less than 0.1 ppb outside source regions. Applying the new rate coefficients implies increased radical concentrations and a more intense O 3 and CO photochemistry. Even for densities of 0.1 ppb or less, NO x still leads to significant local O 3 production and conversion of HO 2 to OH. Unrealistic O 3 profiles are obtained with the new rate coefficients for surface NO x densities of about 1 ppb, while reasonable agreement with observation is obtained with lower NO x densities. Feedback processes between CO, NO x , OH, and CH 4 are also discussed.
Possible non‐linear effects in TRG‐1 Earth tide meters
Authors: Halpenny J. F. , Valliant H. D.
Published: February 2008

Calibration of Geodynamics TRG‐1 and similar non‐nulling earth tide gravimeters indicates that the calibration constant varies with beam position by as much as 20%. The resulting non‐linearity can introduce errors in the determination of the gravimetric factor in the order of 1%. This error level is significant in the determination of gravity tide admittances and in interpreting earth tide measurements for ocean tide effects and regional geology.
An archaeomagnetic paleointensity study of some Hohokam Potsherds From Snaketown, Arizona
Authors: Sternberg R. S. , Butler R. F.
Published: February 2008

A paleointensity study on nine potsherds from the Hohokam Indian site of Snaketown, Arizona is described. The sherds range in age from A.D. 200‐1400. Examination of different temperature subintervals from the Thellier‐Thellier double heating experiment reveals that conventional statistical measures sometimes can unambiguously determine the best data subset for paleointensity calculations. However, it is often necessary to visually inspect the data and utilize physical insight in determining this data subset. Results suggest that the paleointensity was about 0.94 FO (FO, present intensity ≃ 0.506 oe) at A.D. 200, 0.72 FO at A.D. 600, and 1.2 FO at A.D. 1400. The shape of our curve of paleointensity vs. age is congruent with a curve previously derived from other Snaketown artifacts, but our paleointensities are systematically lower by about 0.15 oe.
Low frequency drift oscillations near the plasmapause
Authors: Patel V. L.
Published: February 2008

Drift wave analysis including density temperature gradients of plasma near the plasmapause is considered. The presence of "hot" plasma (T > 10 eV) outside the plasmasphere requires consideration of drift instability condition that the ratio η = ∂1nT/∂1nn remain within certain values. Calculations using possible plasma parameters at the plasmapause show that appropriate values of η exists for the possibility of the drift instability and waves ω ∼ 10−2 rad sec−1 in Pc 3 and Pc 4 range of micropulsations can be internally generated by the plasma inhomogenieties.
Thermal effects of stratospheric ozone depletion at 85°N latitude as influenced by airborne particles
Authors: Reck Ruth A.
Published: February 2008

This work extends our radiative‐convective model calculations to study the influence of particles on the thermal effects of ozone depletion at 85°N latitude, July. The inclusion of particles leads to surface heating when ozone is depleted. Two particle height distributions, one measured and one modeled, but having approximately the same columnar abundance, produced the same thermal effect, 0.018±0.002 K surface temperature increase for each percent of stratospheric ozone depletion. These results are consistent with our results for 35°N latitude obtained previously.
A resolution limitation on sea‐echo radar spectra inferred from point to point ionospheric Doppler broadening
Authors: Heron M. L. , Rose R. J.
Published: February 2008

A 12 MHz radio path over 2000 km has been used to examine the stability of the transmitted frequency over intervals of time generally needed to take a sea state measurement of the ocean surface on a radar backscatter experiment. The variance of observed ionospheric Doppler shifts during successive 100 second intervals is about 0.04 Hz for one hop, point to point propagation predominantly through the F layer. This is expected to double for backscatter paths and to be directly proportional to the carrier frequency. Although the observations apply directly to only one ray in the radar beam and exclude mixed modes on the return path, they indicate a resolution limitation on the second‐order spectra from which sea state conditions may be calculated.
Energetic ions and electromagnetic radiation in auroral regions
Authors: Boswell R. W.
Published: February 2008

It is suggested that energetic ions streaming outward from the earth in the auroral regions will produce electrostatic electron waves. The amplitude of these waves would be limited by nonlinear or possibly linear mode coupling into electromagnetic waves on resonance cones both above and below the electron plasma frequency. Small density irregularities can subsequently refract these waves allowing them to propagate as electromagnetic kilometric radiation or V.L.F. hiss.
Solar wind effects on the surface chemistry of lunar grains
Authors: Bilson Elizabeth
Published: February 2008

Surface enhancements of iron and magnesium in crystals from lunar rock and soil samples have been measured by ion microprobes and were attributed to solar wind implantation of these elements. In this paper it is shown that these surface enhancements and in particular the Fe/Mg surface concentration ratios can also be explained as resulting from the sputter action of solar wind protons and He ions. Furthermore, since these ions are ten thousand times more abundant in the solar wind than ions of the elements which principally constitute the lunar grains, calculations demonstrate that sputtering by protons and He ions moves approximately a hundred times more Mg atoms, for example, than the number of solar wind Mg ions striking the surface. Ion implantation is unlikely, thus, to have a dominant effect on the major element composition of the surface of lunar grains.
Instantaneous auroral particle energy deposition as determined by optical emissions
Authors: Murphree J. S. , Anger C. D.
Published: February 2008

Remote sensing of the N2+ ING 3914Å auroral emission using data from the Auroral Scanning Photometer onboard the ISIS‐2 satellite is employed to determine the energy deposition rate of auroral particles. Techniques have been developed for removing the effects of ground albedo and for obtaining integrated intensities even when the emission region is visible only at the earth's limb. Data from 9 northern hemisphere passes have been selected to illustrate the variation in energy deposition rate with magnetic activity. Measured photon flux rates (photons sec−1 deg−1 of longitude) vary from ∼2 × 1022 to 1.9 × 1025. The peak photon flux for a given pass can occur at magnetic local times varying from 21 to 05 hours. The inferred range of global energy deposition rates (for electron energies 30 eV and above) is 4 × 1016 to 1 × 1019 ergs sec−1.
Three‐satellite measurements and field‐line mapping of the outer plasma sheet boundary from r ∼1.2 to ∼18 RE during substorms
Authors: Pytte T. , Lundjbad J. Å , Söraas F. , Hones E. W. , West H. I.
Published: February 2008

Simultaneous and near‐conjugate observations of energetic particles in the outer region of the plasma sheet by three satellites (Esro 1A, Ogo 5, and Vela 5B) show clear indications of a close relationship between the instantaneous latitudinal location of the high‐latitude precipitation boundary at 1000 to 1500 km height and the thickness of the plasma sheet at geocentric distances of 10 to 18 RE. By comparing low‐altitude and magnetotail particle energy spectra and by using recent magnetospheric field‐line models as spatial reference systems, we find evidence that the precipitation boundary and the outer plasma sheet boundary are magnetically connected. The correlation between plasma sheet recovery and a poleward expansion of the precipitation boundary from Λ ∼70° to ∼75° late in substorms suggests that this recovery is associated with rapid magnetic field‐line reconnection as the reconnection region apparently moves to a more distant location in the tail.
Ionospheric modification: An initial report on artificially created equatorial spread F
Authors: Ossakow S. L. , Zalesak S. T. , McDonald B. E.
Published: February 2008

A numerical simulation code for investigating equatorial Spread F in the collisional Rayleigh‐Taylor regime is utilized to follow the evolution of artificial plasma density depletions injected into the bottomside nighttime equatorial F region. The 70 km diameter hole rapidly rises and steepens, forming plasma density enhancements at altitudes below the rising hole. The distribution of enhancements and depletions is similar to natural equatorial Spread F phenomena, except it occurs .on a much faster time scale. These predictions warrant carrying out artificial injection experiments in the nighttime equatorial F region.
Spectral analyses of high‐frequency Pn,Sn phases recorded on ocean bottom seismographs
Authors: Sutton George H. , McCreery Charles S. , Duennebier Frederick K. , Walker Daniel A.
Published: February 2008

Spectrograms of high‐frequency Pn,Sn phases recorded on ocean bottom seismographs contain frequencies in Pn and Sn wavetrains as high as 10 Hz and 7 Hz, respectively, at distances in excess of 3700 km. These and other observations confirm earlier evidence for remarkable efficiencies of Pn and Sn propagation, with Sn often more efficient (higher apparent Q) than Pn.
The EUV flux inferred from AE‐C He+ abundances
Authors: Oppenheimer M. , Babeu S. , Hoffman J. H. , Breig E.
Published: February 2008

The ionization rate of helium in the thermosphere is inferred from He+ abundances determined by instrumentation on the Atmosphere Explorer‐C satellite. The inferred ionization rate is independent of the particular geophysical parameters of the thermosphere for solar zenith angles less than 80 degrees and altitudes between 280 and 360 km. The ionization rate is consistent with a value calculated from the EUV flux of Hinteregger below 504 Å.