bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysing total ozone for natural and man‐made trend variability
Authors: Bishop Lane , Hill William J.
Published: February 2008

A method is proposed to estimate the effect of long‐term variations in total ozone on the error incurred in determining a trend in total ozone due to man‐made effects. When this method is applied to data from Arosa, Switzerland over the years 1932‐1980, a component of the standard error of the trend estimate equal to 0.6 percent per decade is obtained. If this estimate of long‐term trend variability at Arosa is not too different from global long‐term trend variability, then the threshold (±2 standard errors) for detecting an ozone trend in the 1970's that is outside of what could be expected from natural variation alone and hence be man‐made would range from 1.35% (Reinsel et al, 1981) to 1.8%. The latter value is obtained by combining the Reinsel et al result with the result here, assuming that the error variations that both studies measure are independent and additive. Estimates for long‐term trend variation over other time periods are also derived. Simulations that measure the precision of the estimate of long‐term variability are reported.
Measurements of NO2 and HNO3 during a stratospheric warming at 54°N in February 1979
Authors: Evans W. F. J. , Kerr J. B. , McElroy C. T. , O'Brien R. S. , McConnell J. C.
Published: February 2008

The altitude distribution of HNO3 was measured during a stratospheric warming on a balloon flight from Cold Lake, Alberta, on 11 February, 1979. The HNO3 profile measured appears to be layered and have a greater thickness than that of a typical summer profile. Ground based observations of the zenith sky were made from 31 January to 12 February and yield the total abundance of stratospheric NO2. Stratospheric NO2 column amounts deduced from these ground based measurements and another set taken during February, 1977 exhibit a diurnal variation under dynamical conditions of both stable vortex flow (1977) and stratospheric warming (1979). Using these measurements, the NO measurements of Knight et al. (1982), and model calculations we find that above 20 km there does not appear to be a pronounced seasonal change in total odd nitrogen. However, below 24 km the conversion of NOw = NO + NO2 + 2 × N2O5 + HO2NO2 to HNO3 occurs more rapidly than calculated using current homogeneous chemistry.
The influence of localized precipitation‐induced D‐region ionization enhancements on subionospheric VLF propagation
Authors: Tolstoy A. , Rosenberg T. J. , Carpenter D. L.
Published: February 2008

A two‐dimensional mode propagation model has been used to investigate the effect of localized ionospheric perturbations on the propagation of VLF radio waves in the earth‐ionosphere waveguide. Computations have been performed for the NSS transmissions at 22.3 kHz from Annapolis, Maryland to Eights Station, Antarctica, where anomalous short‐duration signal amplitude changes, in coincidence with whistlers, were first noted. The calculations suggest that two ionization regions, one very near the transmitter and another near the receiver, may need to be present at the same time in order to obtain the large amplitude increases (>3 dB) that are observed to occur on occasion. It is suggested that the former is due to transmitter‐induced electron precipitation, while the latter is due to precipitation associated with the whistler. We also find that small amplitude changes can be obtained under less restrictive ionospheric perturbation conditions.
Broad band airborne water vapor radiometry
Authors: Kuhn Peter M.
Published: February 2008

An infrared radiometer with a pass band of 280 to 520 cm−1 (35.7 to 19.2 µm) is employed on the NASA Ames Research Center U‐2 and C‐141A aircraft in the measurement of water vapor burden in the upper troposphere and stratosphere. Coincidentally with altitude changes the water vapor mass mixing ratio is also inferred by observing the change in optical depth over a known vertical distance. Data from the December 1980 U‐2 Water Vapor Exchange Experiment over the Panama Canal Zone adds to the concept that overshooting cumulonimbus towers “moisten” the lower stratosphere. The average mass mixing ratio in close proximity to or above such towers ranges from 3.5 to 5.0 parts per million above 18 km while the average background mass mixing ratio is only 2.9 parts per million. Generally the lowest background mixing ratios, averaging 2.6 parts per million occurred in the 18 to 21 km layer. For the same levels background Panama mass mixing ratios averaged from 1.0 to 3.0 parts per million higher than in middle latitudes.
Plasma wave levels and IMF orientations preceding observations of interplanetary shocks By Isee‐3
Authors: Greenstadt E. W. , Scarf F. L. , Kennel C. F. , Smith E. J. , Fredricks R. W.
Published: February 2008

Some interplanetary shocks detected by ISEE‐3 are preceded by many hours of strongly‐enhanced plasma wave noise at a few kHz, while others have essentially no wave precursors above background. It has been shown that these extremes correspond to quasi‐parallel and quasi‐perpendicular shocks, respectively, based on the instantaneous orientation angle θBn of the interplanetary magnetic field (IMF) to the shock normal at the time the shocks cross the spacecraft. We show that precursor wave noise level is correlated with field orientation and an extrapolated θBn throughout the preshock observation interval for two contrasting active and quiet cases, and that intermediate, variable noise levels correspond to intermediate, variable IMF orientations. We infer that foreshocks are an intrinsic part of the structure of quasi‐parallel interplantary shocks.
Velocity characteristics of F region irregularities at sub‐auroral latitudes
Authors: Bourdillon A. , Nicollet M. , Parent J.
Published: February 2008

Sub‐auroral F region irregularities have been studied with two HF coherent backscatter radars looking simultaneously at the same irregularity volume from two different locations. Using simple assumptions we have computed the two components of the velocity of the irregularities in a plane perpendicular to B. We present an example of relatively high westward velocity which might be attributed to a subauroral ion drift enhancement.
Influence of the dawn‐dusk potential drop across the polar cap on the high‐latitude atmospheric vertical current
Authors: D'Angelo N. , Iversen I. B. , Madsen M. Møhl
Published: February 2008

Approximately 1200 hours of high‐latitude balloon measurements of atmospheric vertical electric fields and conductivity have been used to derive the UT variation of the ionosphere‐to‐ground vertical current. During geomagnetically quiet days the well known UT modulation, with a minimum at 4‐6 UT and a maximum near 19 UT, is observed. During disturbed days, the dawn‐dusk potential drop across the polar cap clearly influences the vertical current, as was predicted by Park and Dejnakarintra (1977)
Differential helium retention in zircons: Implications for nuclear waste containment
Authors: Gentry Robert V. , Glish Gary L. , McBay Eddy H.
Published: February 2008

A very sensitive helium leak detector was utilized to measure the helium liberated from groups of zircons extracted from six deep granite cores. The observed low differential loss of gaseous helium down to 2900 m (197°C) in these ancient Precambrian rocks is easily attributable to the greater diffusion of He at higher temperatures rather than losses due to corrosion of the zircons. This fact strongly suggests that deep granite burial should be a very safe corrosion‐resistant containment procedure for long‐term waste encapsulation.
Methane: The record in polar ice cores
Authors: Craig H. , Chou C. C.
Published: February 2008

Methane mixing ratios in trapped air in the Dye 3 Greenland ice core decrease from 1.25 ppmv below the firn‐ice transition (∼90 years B.P.) to a baseline value of 0.70 ppmv at a depth of ∼250 m (∼500 years B.P.). Below this level to a depth of 1950 m (∼27,000 years B. P.) the mixing ratio appears to be constant at the base‐line level, and in agreement with data of Robbins et al. (1973) on 700‐2470 year‐old Antarctic ice. The uniformity of these CH4 mixing ratios in both hemispheric ice caps and over some 26 millennia indicates that, whether or not the absolute values correctly reflect the true atmospheric mixing ratios vs. time, the atmospheric CH4 mixing ratios were nevertheless essentially constant over this range of time. Above 250 m depth the trapped‐air CH4 mixing ratios increase linearly up to ∼100 m depth, and then increase sharply just below the firn‐ice transition. The mixing ratio vs. age trajectory is strongly offset from the estimated atmospheric record of the past 15 years, but when corrected for the ∼90 year difference in age of air and ice at firn closure, the ice‐core data track quite precisely into the recent atmospheric record. Thus we believe that these data correctly reflect past CH4 atmospheric mixing ratios. The increase in atmospheric methane concentration begins at ∼1580 A.D. and amounts to ∼0.40 ppmv by 1918, and ∼0.90 ppmv by 1980; the equilibrium greenhouse warming associated with this increased CH4 concentration is about 0.23°C over the past 400 years, and at the current rate of increase the warming due to CH4 is about 38% of the CO2 warming effect.
Thinning of field‐aligned currents
Authors: Dungey J. W.
Published: February 2008

It is common to describe the field‐aligned currents associated with auroral arcs in terms of an Alfven wave propagating earthward. Taking account of convection, the wave can be stationary relative to the earth with its normal nearly perpendicular to the field. Far enough ahead of the wave linear theory is valid and here theory is restricted to both the linear and cold plasma approximations, but is sufficient to yield a significant result. This predicts that, as the wave propagates towards the earth, the wave normal becomes more nearly perpendicular to the field and the characteristic thickness decreases.
The effect of excess CO2 on the calculated calcite and aragonite saturation horizons in the northeast Pacific
Authors: Feely Richard A. , Chen Chen‐Tung A.
Published: February 2008

Using the ΔTCO2° results of Chen (1982a) obtained during a cruise in the northeast Pacific Ocean (June‐July 1981), we have calculated preindustrial and 1981 calcite and aragonite saturation horizons for a transect along 150°W between Alaska and Hawaii. Uptake of excess CO2 by the oceans over the past 130 years has resulted in a significant change in the carbonate chemistry of the northeast Pacific Ocean. The results indicate an apparent reduction in the thickness of the supersaturated lenses and an upward translation of the 100% saturation level by as much as 150 meters for calcite and 70 meters for aragonite in the coldwater region north of the Subarctic Front.
Acetonitrile in the lower troposphere
Authors: Becker K. H. , Ionescu A.
Published: February 2008

Measurements of air samples taken near the ground at different locations in urban as well as in rural areas show the presence of acetonitrile (CH3CN) in concentrations up to 7 ppbv. The measurements of this compound were carried out by a gas chromatographic method with an electron capture detector and by a mass spectrometric method with a GC‐MS quadrupol mass filter system. The present results support tropospheric sources for acetonitrile recently found in stratospheric ion‐clusters.
Temperature effects on the stratosphere of the April 4, 1982 eruption of El Chichon, Mexico
Authors: Labitzke K. , Naujokat B. , McCormick M. P.
Published: February 2008

Monthly mean stratospheric temperatures at 50‐ and 30‐mbars between 10° and 30°N for the years 1964‐1981 are compared with data for 1982. It is shown that the 30‐mbar temperatures at 10°N increased in July, August, September, and October 1982 to values well above those shown for the previous 18 years. We believe this to be caused by aerosols produced from the recent eruptions of El Chichon (17.33°N, 93.2°W) on April 4, 1982. This is the first time that a direct connection between an increase of stratospheric temperatures and an increased aerosol load has been established in real time.
Visible glow induced by spacecraft‐environment interaction
Authors: Yee J. H. , Abreu V. J.
Published: February 2008

Illumination was found recently in the ram direction of the Shuttle Orbiter arising from interaction with the ambient surrounding atmosphere. We have examined a similar optical glow by analyzing photometric data taken by the Visible Airglow Experiment on board the Atmosphere Explorer Satellites. Analysis at six different wavelengths from the ultraviolet to the near infrared suggests that the glow has a diffuse band or continuum spectrum which peaks in the red and probably in the infrared.
Conjectures on the origin of the surface glow of space vehicles
Authors: Slanger Tom G.
Published: February 2008

It is argued that a plausible identification of the surface‐originating glow that has been observed on the AE‐E satellite and the space shuttle between 140 and 400 km is the OH Meinel band system. The emission appears to be generated by surface interaction with 5 eV O(³P) atoms at high altitude, and with 10 eV O2 molecules below 160 km. The primary factors that favor this identification are the apparent spectral distribution and the deduced radiative lifetime, and if valid, implies that the total equivalent surface brightness of the vehicles is on the order of 10 MR, mainly in the near infrared.
Oxides of nitrogen at two sites in New Zealand
Authors: Stedman D. H. , McEwan M. J.
Published: February 2008

Oxides of nitrogen, ozone and solar UV radiation were measured at two New Zealand sites, four months at Mt. John near Lake Tekapo, and one month at the New Zealand Department of scientific and Industrial Research, Physics and Engineering Laboratory Atmospheric Station (PELAS) near Lauder. The former site proved ideal for clean‐air measurements. Ozone concentrations of ∼20‐25 ppb, with little diurnal variation were accompanied by total nitrogen oxide (NOy) levels frequently less than 150 ppt (parts in 1012 by volume). The noon NO and NO2 data were well correlated with a slope comparable to model values. Gaseous HNO3 was observed to be significantly above the noise level (∼15 ppt) for only twenty‐seven four‐hour averages. For these a median of 43 ppt was obtained with a median ([NOy]‐[HNO3])/[HNO3] ratio of 7.5, not comparable with model values of around 1.1. This low HNO3 may arise from the fact that the Mt. John site is downwind of a mountain range which experiences significant upwind precipitation. At the PELAS site, strong diurnal variation of ozone and much larger NOy concentrations were observed. The difference is apparently caused by local sources of nitrogen oxides and the local meteorology at the fertile valley PELAS site.
Continental lithospheric thickness and deglaciation induced true polar wander
Authors: Peltier W. R. , Wu Patrick
Published: February 2008

The secular drift of the earth’s rotation pole, which is evident in ILS data, is a memory of the planet of the last deglaciation event of the current ice age. In order to fit the observed rate and direction of drift with an earth model whose viscosity profile is capable of reconciling the free air gravity and relative sea level data of postglacial rebound, requires a lithospheric thickness which is substantially in excess of that which might be considered an appropriate average thickness for the entire planet. This required thickness, which is greater than 250 km, is nevertheless in accord with independent estimates of the thickness of the continental lithosphere.
Ozone density distribution in the mesosphere (50‐90 km) measured by the SME limb scanning near infrared spectrometer
Authors: Thomas R. J. , Barth C. A. , Rottman G. J. , Rusch D. W. , Mount G. H. , Lawrence G. M. , Sanders R. W. , Thomas G. E. , Clemens L. E.
Published: February 2008

The ozone densities between 50 and 90 km are deduced from 1.27 µm airglow measured on the Solar Mesosphere Explorer satellite. The derived densities agree well with those made simultaneously from SME by the ultraviolet spectrometer. The data set extends from pole to pole at about 3 pm, for most sunlit latitudes. At low altitudes, in the mesosphere, there are larger variations in ozone density in the winter latitudes than in the summer. Above the meso‐pause the day‐to‐day variation in ozone density is a factor of two at most latitudes and times.
Lamb pulse observed in nature
Authors: Kanamori Hiroo , Given Jeffrey W.
Published: February 2008

Seismograms observed at Longmire, Washington, for four eruptions of Mt. St. Helens (May 18, June 13, August 7, and August 8, 1980), can be interpreted as Lamb pulses excited by a nearly vertical single force that represents the counter force of the eruption. These data provide reliable estimates of the impulse of the force K (time integral of the force) from which the total momentum and the kinetic energy, E, of the ejecta associated with the eruption can be estimated. The values of K are estimated to be 1.4 × 1019, 1.4 × 1016, 3.7 × 1015, and 2.8 × 1015 dyne·s for the four eruptions (chronological order), respectively. The corresponding values of E are estimated to range from 0.70 to 2.6 × 1023, 0.70 to 2.6 × 1020, 1.9 to 6.9 × 1019, and 1.4 to 5.3 × 1019 ergs using values of ejecta velocity ranging from 100 to 375 m/s. The ratio of K to the amplitude of the air wave excited by the eruption is 20 to 40 times larger for the main event on May 18 than for the other events suggesting a significant difference in the eruptive mechanism. Our results demonstrate that a digital seismograph in the vicinity of volcanoes provides a simple means for quantification of the explosive power of a volcanic eruption.
Gas exchange in the Pee Dee River based on 222Rn evasion
Authors: Elsinger Robert J. , Moore Willard S.
Published: February 2008

Excess 222Rn concentrations decrease downstream in the fresh water section of the Pee Dee River. Ground water is the primary source of the excess 222Rn to the River. Using the radon concentration gradients determined during four sampling periods, gas exchange rates based on the stagnant film model are calculated. Stagnant film thicknesses range from 19µm to 48µm and mass transfer coefficients range from 2.1 m/d to 4.1 m/d.
Correlative studies of satellite ozone sensor measurements
Authors: Lovill J. E. , Ellis J. S.
Published: February 2008

Comparisons are made between total ozone measurements made by four satellite ozone sensors (TOMS, SBUV, TOVS and MFR). The comparisons were made during July 1979 when all sensors were operating simultaneously. The TOMS and SBUV sensors were observed to measure less total ozone than the MFR sensor, 10 and 15 Dobson units (DU) respectively. The MFR and TOMS sensors measured less ozone than the TOVS sensor, 19 and 28 DU, respectively. Latitudinal variability of the total ozone comparisons is discussed.
Computer simulation of auroral kilometric radiation
Authors: Wagner J. S. , Lee L. C. , Wu C. S. , Tajima T.
Published: February 2008

We study the generation of auroral kilometric radiation (AKR) using relativistic, electromagnetic, particle simulations. The AKR source region is modeled by two electron populations in the simulation: a cold (200ev) Maxwellian component and a hot (5‐20kev) population possessing a loss‐cone feature. The loss‐cone distribution is found to be unstable to the cyclotron maser instability. The fast extraordinary (X‐mode) waves dominate the radiation and saturate when resonant particles diffuse into the loss‐cone via turbulent scattering of the particles by the amplified X‐mode radiation.
An alternative method for fault‐plane solutions from a single station
Authors: Ingate Shane F.
Published: February 2008

An alternative to the method of Langston (1982) for determining fault‐plane solutions from a single 3‐component seismic station is proposed. The method calculates synthetic P and SH seismograms for three basic orientations of a shear dislocation embedded in a plane layered Earth model, and uses least‐squares to minimise the error between the observed data and a linear sum of the synthetic seismograms. The result is five trigonometric functions of fault strike θ, fault dip δ, and rake of the slip vector λ. When applied to the Borrego Mountain event of 9 April 1968, the method provides a solution which is in close agreement with well‐constrained studies of the main shock.
The mechanism of sulfate aerosol formation: Chemical and sulfur isotopic evidence
Authors: Saltzman E. S. , Brass G. W. , Price D. A.
Published: February 2008

In order to study the mechanism of aerosol sulfate formation, weekly samples of SO2 and aerosol SO4= were collected at Hubbard Brook Experimental Forest, West Thornton, New Hampshire from July to December, 1980. Samples were analyzed for concentration and sulfur isotopes (δ34S). Late summer‐early fall samples are characterized by high, variable SO4= levels and low SO2 levels, while late fall ‐ early winter samples exhibit low SO4= and high SO2 levels. These trends suggest that the oxidation rate varies seasonally, with faster oxidation during warmer months. The sulfur isotopic fractionation between aerosol SO4= and SO2 is intermediate between that expected from homogeneous and heterogeneous reactions, indicating that both processes can be important. The isotopic data suggest that homogeneous oxidation reactions are more important than solution reactions, particularly during warm months.
Results of apparent atomic oxygen reactions on Ag, C, and Os exposed during the Shuttle STS‐4 orbits
Authors: Peters P. N. , Linton R. C. , Miller E. R.
Published: February 2008

Films selected for anticipated reaction with atomic oxygen, namely carbon, silver, and osmium, were exposed during the Shuttle STS‐4 mission. A silver film 225 ± 5 nm thick was converted to a transparent blue‐green interference film 355 ± 5 nm thick. Both carbon and osmium films 10‐30 nm thick apparently formed volatile oxides and disappeared, except where well shielded. A calculated total of approximately 7 × 1019 oxygen atoms per cm² struck the surfaces, which could have removed on the order of 3 µm of material if only 10% reacted. The absence of apparent effects on adjacent thin and thick gold films is offered as evidence that sputtering is not responsible.
Computer simulation studies of VLF triggered emissions deformation of distribution function by trapping and detrapping
Authors: Matsumoto Hiroshi , Omura Yoshiharu
Published: February 2008

A simulation study of VLF triggered emissions has been carried out in order to investigate quantitative changes of the velocity distribution function of resonant electrons caused by a combined action of nonlinear phase‐trapping and geomagnetic inhomogeneity. It is a counter‐part of the an analytic theory proposed by Roux and Pellat. The result basically supports their idea which is based on a simplified assumption. It also gives detailed information of more complicated behavior of both trapped and untrapped particles. It is pointed out that the contribution by electrons which are trapped in the midst of the whistler wave train is as important as that by electrons trapped at the wave‐front. It is further revealed that deformation of the velocity distribution function is caused not only by trapped electrons but also by untrapped electrons perturbed by a whistler triggering wave. The well‐known characteristics of pulse length dependence of rising or falling tone characteristics of triggered emissions is interpreted by the present simulation result.
Observations of VLF transmitter‐induced depletions of inner zone electrons
Authors: Vampola A. L.
Published: February 2008

Precipitation spikes of electrons, in which the energy spread of the peak is narrow (less than 50 keV) and the peak energy is a strong function of the location in L, have been observed in the region 1.5 < L < 2.0 and have been ascribed to interactions between waves from high power VLF transmitters on the ground and the precipitated electrons [Vampola and Kuck, 1978; Imhof et al., 1981]. On numerous occasions when these spikes were observed at low altitude by instrumentation on the S3‐2 satellite, a significant depletion of electrons at the same energies was observed high on the field line. These depletions indicate that the loss rate of electrons due to VLF transmitters is significant and usually exceeds the rate at which radial diffusion is refilling those field lines. Electrons with energies between 36 keV and 317 keV in the region 1.9 < L < 1.6 were observed to have lifetimes limited to a few days by interactions with waves from VLF transmitters. Thus the outer edge of the inner zone is defined by this wave‐particle process.
Electromagnetic ion‐cyclotron instability in the multi‐ion Jovian magnetosphere
Authors: Thorne Richard M. , Moses Julie
Published: February 2008

Propagation characteristics of electromagnetic ion‐cyclotron waves are extremely sensitive to the relative composition of thermal ions: this can consequently control the instability properties of resonant energetic ions in the Jovian magnetosphere. The dominance of heavy ions in the Io plasma torus will suppress ion‐cyclotron instability near the equatorial plane. Wave growth, however, can still occur away from the equator in the region where thermal hydrogen is expected to predominate. A theoretical assessment of the convective L‐mode gain indicates that Voyager 1 did not enter the preferred region of instability. Evidence for instability may nevertheless be available since oblique ion‐cyclotron waves are expected to experience a natural polarization reversal to the R‐mode which is able to propagate from high latitudes to the equator. If the amplitude of the unstable L‐mode waves exceed a gamma the concomitant scattering rate of resonant energetic ions should approach the strong diffusion limit. In the absence of significant Landau damping the power spectral density of fluctuating (≳10 Hz) R‐mode electric fields detectable near the equatorial plane by the Voyager plasma wave instrument could then exceed 10−7(V/m)²Hz−1 in the inner torus. Such intense ion‐cyclotron waves could account for the observed decrease in ion phase space density and the excitation of auroral emissions on field lines mapping from the Io torus.
acetonitrile in the atmosphere
Authors: Brasseur G. , Arijs E. , De Rudder A. , Nevejans D. , Ingels J.
Published: February 2008

The vertical distribution of acetonitrile between 0 and 55 km altitude is calculated assuming that CH3CN is released at the Earth's surface and that the main loss process in the stratosphere is the reaction with hydroxyl radicals. The influence of different possible surface concentrations is investigated. The role of the destruction of CH3CN by Cl, as well as the use of different eddy diffusion coefficients is briefly discussed. The results are compared with recent measurements of acetonitrile.
Stratospheric sulfate from El Chichón and the Mystery Volcano
Authors: Mroz E. J. , Mason A. S. , Sedlacek W. A.
Published: February 2008

Stratospheric sulfate was collected by high‐altitude aircraft and balloons to assess the impacts of El Chichón and an unidentified volcano on the stratosphere. The Mystery Volcano placed about 0.85 Tg of sulfate in the northern hemisphere stratosphere. El Chichón injected about 7.6 Tg sulfate into the global stratosphere.
El Chichon eruption cloud: Comparison of lidar and optical thickness measurements for October 1982
Authors: Swissler T. J. , McCormick M. P. , Spinhirne J. D.
Published: February 2008

Sun photometer and lidar backscatter measurements of the El Chichon volcanic cloud were obtained during an airborne latitude survey. The observations were collected between 46°N and 46°S from October 19 to November 7, 1982. Comparisons between these data sets have been performed. An aerosol optical model was developed for the conversion of the lidar measurements to optical thickness values using numerical aerosol size distribution data and index of refraction information collected with coordinated dustsonde balloon flights. The derived lidar optical thickness values were found to agree with the sun photometer optical thickness values within measurement uncertainties. The lidar derived values ranged from 0.16 at the equator to 0.03 at 30°S latitude. Peak values were concentrated between 35°N and 10°S.
Examination of wintertime latitudinal gradients in stratospheric No2 using theory and LIMS observations
Authors: Callis L. B. , Russell J. M. , Haggard K. V. , Natarajan M.
Published: February 2008

Nimbus 7 LIMS data and a photochemical model are used to show that the observed sharp latitudinal gradients in stratospheric wintertime NO2 are consistent with the conversion of NO2 to N2O5 at high latitudes. This conversion, and the sharp gradients, are brought about by the interaction between transport and photochemistry. Calculated variations show good agreement with observations.
Earth magnetic field fluctuations produced by filamentation instabilities of electromagnetic heater waves
Authors: Kuo S. P. , Lee M. C.
Published: February 2008

A mechanism associated with the filamentation instabilities of circularly polarized waves is investigated, showing the capability of producing significantly large earth magnetic field fluctuations in addition to ionospheric density fluctuations. This mechanism is suggested as the cause of earth magnetic field fluctuations reported by Stubbe and Kopka (1981) in the ionospheric heating experiments performed at the EISCAT facilities in Tromso, Norway.
The El Chichon cloud over central Europe, observed by Lidar at Garmisch‐Partenkirchen during 1982
Authors: Reiter R. , Jäger H. , Carnuth W. , Funk W.
Published: February 2008

The transport to northern midlatitudes of stratospheric aerosol layers originating from the 4 April 1982 explosive eruption of the Mexican volcano El Chichon took place in three phases: Appearance of a stable low altitude aerosol layer (tropopause to 20 km) in May, observable until October; appearance of a second, rather variable, high altitude layer (above 20 km) in June, observable until October; formation of a broad layer in October, extending from the tropopause to 30 km, and a subsequent steady increase of the aerosol loading until the end of 1982. Observed lidar backscattering profiles have been converted to optical depth and column mass values. Respective December 1982 averages of 0.13 at 550 nm and 0,04 g m−2 have been derived.
Spectroscopic measurements of the 8‐ to 13‐micrometer transmission of the upper atmosphere following the El Chichon eruptions
Authors: Witteborn F. C. , O'Brien K. , Crean H. W. , Pollack J. B. , Bilski K. H.
Published: February 2008

Infrared transmission spectra of the atmosphere above 11‐km altitude were obtained at latitudes from 2° S to 50° N in December 1982. A circular variable‐interference filter spectrometer mounted in a Convair 990 (the Galileo II) aircraft was used to obtain spectra of the Sun through different air masses. Comparisons of spectra through different air masses provide atmospheric transmission measurements that show not only normal absorption features, such as those from CO2 and O3, but also additional absorption near 8.5 µm consistent with H2SO4 aerosols. The average fractional absorption from latitude 10° N to 41° N at 8.5 µm was 0.02/air mass, half of which was attributable to aerosols.
Halocarbon concentration patterns associated with frontal passages
Authors: Carter Michael W. , Cronn Dagmar R. , Bamesberger W. Lee , Robinson Elmer
Published: February 2008

The atmospheric mixing ratios of CCl2F2 (F‐12) and CCl3F (F‐11) increase abruptly up to 14 ppt (F‐12) and 8 ppt (F‐11) after strong cold fronts pass and decrease abruptly after warm fronts pass at a semi‐continuous monitoring station near Pullman, Washington (46°42′N, 117°10′W). We conclude that air masses from higher latitudes (>60°N) can have F‐12 and/or F‐11 concentrations as much as 5% higher than mid‐latitude air masses. Conversely, nitrous oxide shows no significant changes during frontal passages and is uniformly distributed between air masses.
Effect of the α ‐ β quartz transition on the creep properties of quartzite and granite
Authors: Ross John V. , Bauer Stephen J. , Carter Neville L.
Published: February 2008

Cylinders of dry Sioux Quartzite and Westerly Granite have been deformed in creep under transient conditions at 200 MPa confining pressure in the temperature interval 480° to 783°C. This temperature range spans the α ‐ β quartz transition which affects the creep behavior of both rocks profoundly, as was observed previously for synthetic single crystals of quartz. Activation energies and creep rates measured at 0.3% strain are appreciably lower in the β‐quartz stability field then in the α‐field. Deformation is semibrittle over the conditions explored. These results establish that quartz controls the creep rate of granite at least to low strains in the transient creep regime.
Lightning measurements from the Pioneer Venus Orbiter
Authors: Scarf F. L. , Russell C. T.
Published: February 2008

The plasma wave instrument on the Pioneer Venus Orbiter frequently detects strong and impulsive low‐frequency signals when the spacecraft traverses the nightside ionosphere near periapsis. These particular noise bursts appear only when the local magnetic field is strong and steady and when the field is oriented to point down to the ionosphere thus; the signals have all characteristics of lightning whistlers. We have tried to identify lightning sources between the cloud layers and the planet itself by tracing rays along the B‐field from the Orbiter down toward the surface. An extensive data set, consisting of measurements through Orbit 1185, strongly indicates a clustering of lightning sources near the Beta and Phoebe Regios, with an additional significant cluster near the Atla Regio at the eastern edge of Aphrodite Terra. These results suggest that there are localized lightning sources at or near the planetary surface.
Observation of plasma deceleration at a rotational magnetopause discontinuity
Authors: Aggson T. L. , Maynard N. C. , Ogilvie K. W. , Scudder J. D. , Gambardella P. J.
Published: February 2008

This letter presents a detailed experimental analysis of the electric fields and electron flow velocities at a rotational magnetopause discontinuity. It is shown for this event that the magnetosheath plasma velocity is sharply decelerated on entry into the magnetosphere in very good agreement with a theoretical magnetohydrodynamic fit. This type of event is remarkable because the quantity E · J is negative during the magnetopause crossing. This case represents one of two types of valid solution to the MHD boundary conditions. It differs from previously published examples of reconnective magnetopause geometries in that energy is being transferred locally from kinetic energy into electromagnetic energy at the time of these measurements.
Fission‐track geochronologic evidence for Late Cretaceous mylonitization and Early Paleocene uplift of the northeastern Peninsular Ranges, California
Authors: Dokka Roy K.
Published: February 2008

Fission‐track dating of minerals from the Santa Rosa Mylonite Belt and adjoining rocks of the northeastern Peninsular Ranges batholith indicates that the area was affected by a brief, but intense cooling event approximately 61 m.y. ago. Concordant ages from different mineral species suggest a minimum temperature drop of ∼120°C during this event. This rapid cooling event probably reflects major uplift and unroofing of the batholith at the beginning of the Paleocene. These new data coupled with other published isotopic data, firmly establishes that the Santa Rosa Mylonite Belt formed during the Late Cretaceous.
Detection of synoptic‐scale vertical velocities using an MST radar
Authors: Nastrom G. D.
Published: February 2008

Comparisons of the time‐averaged vertical velocity observations from the Platteville, CO, MST radar with synoptic‐scale vertical velocities computed by the adiabatic and quasi‐geostrophic omega equation methods are made for several case studies. These first results show that an MST radar can detect synoptic‐scale vertical velocities and that at Platteville the most favorable comparison occurs when the synoptic‐scale vertical velocity is large and the temporal variance of the MST radar data is small.
Springtime stratospheric NO2 in Antarctica
Authors: McKenzie R. L. , Johnston P. V.
Published: February 2008

We present springtime measurements of column amounts of stratospheric nitrogen dioxide measured by ground based absorption spectroscopy from Scott Base, Antarctica (77.8°S, 166.7°E). There is a rapid build up from <1 × 1015 molecules cm−2 at the end of August to about 5 × 1015 molecules cm−2 by mid October. The period covered is the transition time between winter night, and summer day; and in general the ‘overnight’ decay of NO2 is small. The decay is most significant at times when the number of hours of sunlight per day exceeds 12 hours. There are large day to day variations in column amounts which indicate that transport is a significant factor.
Modulation of solar irradiance by active regions
Authors: Schatten Kenneth H.
Published: February 2008

It is shown that in active region modelling of solar irradiance variations, care should be taken not to simply use average contrasts of faculae. This is particularly the case if the model then ignores active region facular areas when the facular contrasts are low, as this then doubly devalues the contribution of faculae relative to sunspots.
Neutron diffraction study of titanomagnetites
Authors: Boysen H. , Schmidbauer E.
Published: February 2008

Using neutron diffraction, the cation distribution was determined in compositions of the titanomagnetite spinel series Fe3−xTixO4 O ≤ × ≤ 1, with x = 0.6 and 1 at room temperature. The knowledge of the correct cation distribution of x = 0.6 is necessary for predicting the change in magnetization of ozeanic pillow basalts with oxidation. For x = 0.6, Ti ions occupy exclusively B‐sites of the spinel lattice with the possible exception of a minute number occupying A‐sites. In order to explain the diffraction pattern for x = 1, the occupation of additional kinds of sites are discussed. The diffuse scattering in the background for both compounds shows broad peaks which are indicative of magnetic and chemical short range order.
Stare observations of an eastward propagating Pc5 pulsation with large azimuthal wavenumber
Authors: Walker A. D. M. , Nielsen E.
Published: February 2008

The results of observations by the Stare radar of an eastward propagating Pc5 pulsation with short azimuthal wavelength are presented. Previously observed high‐m phenomena have been propagating westward. This event occurred in the predawn sector during a time of substorm activity. The azimuthal wave number is m = 30 ± 3. Calculations of the drift and bounce periods of energetic particles show that the most plausible particle resonances are with near‐equatorial drifting electrons in the 5 to 20 keV range or with bounce resonant protons in the 0.03 ‐ 1 keV range. If the drift mirror instability is important it must be with guiding center‐drifting electrons or the wave velocity must match the diamagnetic drift velocity which is only possible if the pressure gradient is inwards.
A zonally symmetric model for volcanic influence upon atmospheric circulation
Authors: Schatten Kenneth H. , Mayr Hans G. , Harris Isadore , Taylor Harry A.
Published: February 2008

We consider the effects of volcanic activity upon zonal wind flow in a model atmosphere. A low latitude volcanic eruption could lower the tropospheric pole to equator temperature difference and thereby affect the atmospheric motions. When the temperature contrast decreases, the zonal wind velocities at high altitudes are reduced. To conserve angular momentum, the velocities in the lower atmosphere near the surface must increase, thus providing a momentum source for ocean currents. We suggest that this momentum source may have played a role as a trigger for inducing the 1982‐83 anomalous El Nino and possibly other climate changes.
Neutral winds in the high latitude winter F‐region: Coordinated observations from ground and space
Authors: Killeen T. L. , Smith R. W. , Hays P. B. , Spencer N. W. , Wharton L. E. , McCormac F. G.
Published: February 2008

Coordinated measurements of the F‐Region neutral wind field in the northern (winter) polar cap are reported using instrumentation on board the Dynamics Explorer (DE‐2) satellite and the Ulster College ground‐based Fabry‐Perot interferometer sited at Svalbard (UFPI). The satellite observations provide the full neutral wind vector along the track of the polar orbiting spacecraft with the meridional component measured by the Fabry‐Perot Interferometer (FPI) and the zonal component measured by the Wind and Temperature Spectrometer (WATS). The UFPI observations provide a set of four horizontal wind components in the cardinal directions which may be merged to give two individual neutral wind vectors for each measurement cycle (duration ∼30 minutes). A comparison of data from the ground and spaceborne sensors for simultaneous, near common‐volume observations indicates good agreement between the observational techniques. Simultaneous observations made when the Svalbard observatory and DE‐2 were in different local time sectors of the northern polar cap provide a more detailed “snap‐shot” of the neutral circulation pattern than possible using either technique alone. The measurements show the presence of a large‐scale, anti‐cyclonic vortex system on the evening and day‐side sectors of the winter polar cap.
Ground‐based measurements of Arctic haze made at Alert, N.W.T., Canada, during the Arctic Gas and Aerosol Sampling Project (AGASP)
Authors: Hoff R. M. , Trivett N. B. A.
Published: February 2008

Ground‐based measurements of Arctic haze were made which are comparable with data obtained aboard the National Oceanographic and Atmospheric Administration (NOAA) P‐3 aircraft during March, 1983. Measurements of particle size distribution, particle ionic speciation, and condensation nuclei concentration were made at Alert, N.W.T., from March 16‐30. Comparison with the long‐term data taken by the Canadian Arctic Air Sampling Network shows that the period is typical of haze maxima in previous years. These data allowed a favorable comparison of the particle size distribution from the aircraft and ground sampler to be made.
Gaseous bromine in the Arctic and Arctic haze
Authors: Rasmussen R. A. , Khalil M. A. K.
Published: February 2008

We report the results of measurements of five bromine‐containing trace gases (CBrClF2, CH2BrCl, CH2Br2, CH2BrCH2Br, and CH3Br) in the arctic during 1983 and during two of the spring 1983 AGASP aircraft flights. The results show that the anthropogenic bromine‐containing trace gases CBrClF2, CH2BrCl, and CH2Br2 are more abundant during the winter or spring when arctic haze is observed. The same gases are also more abundant in the haze layers compared to their concentrations out of the haze as measured during the AGASP flights. The total bromine we measured in the arctic, however, appears to be only around 30 pptv, being about 10% more during spring when arctic haze is observed compared to the rest of the year.
High‐frequency wave normals in the solar wind
Authors: Herbert Floyd , Smith Larry D. , Sonett C. P.
Published: February 2008

High‐frequency (0.01 ‐ 0.04 Hz) magnetic fluctuations in 506 ten‐minute intervals of contemporaneous Explorer 35 and Apollo 12 measurements made in the solar wind near the morning side of the Earth's bow shock show the presence of a large population of disturbances resembling Alfvén waves. Each wavefront normal n is systematically aligned (median deviation = 35°) with , the associated ten‐minute average of the magnetic field. Because of variability in the direction of  from one interval to another, the coupled distribution of n is nearly isotropic in solar ecliptic coordinates, in contrast with the results of other studies of waves at much lower frequency indicating outward propagation from the sun. Presumably the high frequency waves discussed here are stirred into isotropy (in solar ecliptic coordinates) by following the low frequency fluctuations. As these waves maintain their alignment of n with  despite the great variation of , a strong physical alignment constraint is inferred.
Interannual length‐of‐day variation with relation to the southern oscillation/El Nino
Authors: Fong Chao B.
Published: February 2008

The atmospheric and oceanic mass transport associated with the southern oscillation/El Nino will inevitably induce an interannual variation in the length of day. We conduct an empirical correlation study by comparing the Southern Oscillation Index time series and the interannual length‐of‐day variation (obtained by removing the long‐period and short‐period variations from a BIH length‐of‐day series) for the period 1957‐1983. The two series has a very encouraging qualitative correlation, in particular with respect to El Nino events; and the linear correlation coefficient is found to be 0.55. It is believed that much, if not most, interannual length‐of‐day variation is caused by the southern oscillation, and the true correlation is considerably higher than its apparent value considering the fact that the Southern Oscillation Index is merely an indicator derived from two local atmospheric measurements.
Atmospheric implications of simultaneous nighttime measurements of NO3 radicals and HONO
Authors: Pitts James N. , Biermann Heinz W. , Atkinson Roger , Winer Arthur M.
Published: February 2008

Atmospheric concentrations of gaseous HONO and the NO3 radical were measured simultaneously for the first time using long path differential optical absorption spectroscopy. Diurnal profiles are reported for two successive nights following days of moderate pollution at Riverside, California, together with concurrent measurements of NO2, O3 and NO concentrations and an upper limit for HCHO levels. These measurements permit an examination of selected aspects of the nighttime atmospheric chemistry of HONO and the NO3 radical and related species. Our data do not support a recently proposed homogeneous gas phase mechanism for HONO formation initiated by the reaction of the NO3 radical with HCHO.
Interaction between neutral hydrogen and solar wind: Spacecraft measurements of H+ at the Earth's orbit
Authors: Egidi A. , Francia P. , Villante U.
Published: February 2008

Measurements taken by the solar wind experiment aboard the ISEE 2 satellite show evidence for H+ ions, originating from neutral hydrogen moving with a speed much lower than that of the solar wind.

Positive ion fluxes are measured as a function of energy and flow direction and accumulated over a time of few hours, in which the solar wind and magnetic field parameters remain approximately constant. A model given by Vasyliunas and Siscoe (1976) is used to predict the expected location of these ions in velocity space. A consistent correlation is found between predictions and measurements in three periods of time; order of magnitude estimates of the ion flux range between 104 and 105 cm−2 s−1. In the region surrounding the Earth, the neutral hydrogen consists primarily of interstellar and geocoronal gas. The present preliminary results presented do not allow to evaluate the relative contributions of the two populations to the observed fluxes.
Surface wind measurements in Sequal I
Authors: Payne Richard E.
Published: February 2008

Data from meteorological recorders at 29.37W, 24.00W and 14.93W, all within one degree latitude of the equator, show that a relaxation event in the wind speed occurred nearly simultaneously at all three during late March 1983 during SEQUAL I. Wind stress subsequently increased by approximately a factor of two. The event was not recognizable in the data from a fourth recorder at 6.10N, 27.88W.