bluuebunny/crossref_metadata_2025_split huggingface dataset:
Foreword [to Long‐Term Sea Level Changes]
Authors: Cloetingh Sierd 
Published: February 2008

This special section contains a selection of papers presented at the AGU Chapman Conference on Long‐Term Sea Level held in Snowbird, Utah, April 17–20, 1989. The conference was convened by Dork Sahagian and Anthony Watts and was attended by a group of researchers active in a wide range of subjects dealing both with causes and expressions of sea level change. Sea level variations form one of those central topics in earth sciences that is beginning to bridge the gap between otherwise remote fields such as postglacial rebound dynamics, intraplate tectonics, sedimentary geology, and isotope analysis.The conference was the site of intensive debate, and the papers presented in this special section demonstrate the need for an integrated approach to make further advances in our understanding of sea level change. Integrated research on fundamental questions, including the relative roles of tectonics and eustasy and the issue of global synchroneity of sea level change, has actually only recently begun. It is our hope that the present section will stimulate much further research on these topics.
NASA sea ice validation program for the Defense Meteorological Satellite Program special sensor microwave imager
Authors: Cavalieri Donald J. 
Published: February 2008

The launch of the first Defense Meteorological Satellite Program (DMSP) special sensor microwave imager (SSM/I) on June 19, 1987, was of particular significance to the polar research community in that it extended the series of polar‐orbiting passive microwave imager s which began with the Nimbus 5 electrically scanning microwave radiometer (ESMR) in 1972 and continued until August 1987 with the Nimbus 7 scanning multichannel microwave radiometer (SMMR). Six additional SSM/I instruments will be launched over the next 2 decades as part of the DMSP program.In 1982, in recognition of the importance of the SSM/I to the polar research community, NASA established a program to process, archive, and distribute gridded SSM/I microwave radiances and derived sea ice concentrations for both polar regions. A key element of this effort was the initiation of a sea ice validation program for the purpose of providing the user community a measure of the precision and accuracy of the derived sea ice products. Sea ice remote sensing specialists were invited to serve on the NASA sea ice validation team to define and implement the program [Cavalieri and Swift, 1987]. A parallel program which included other geophysical parameters was established by the Department of Defense under the leadership of J. P. Hollinger at the Naval Research Laboratory [Hollinger, 1989].
Nonlinear magnetosonic waves and mirror mode structures in the March 1991 Ulysses interplanetary event
Authors: Tsurutani Bruce T. , Southwood David J. , Smith Edward J. , Balogh Andre 
Published: February 2008

In examining the March 23–25, 1991 Ulysses (2.2 AU) high speed solar wind events, we find two distinct plasma wave modes: steepened magnetosonic waves with whistler precursors and mirror mode structures. These two modes are locally generated by plasma instabilities, presumably associated with anisotropies existing in the energetic shock particles and solar wind plasma, respectively. The magnetosonic waves are generated by a right‐hand resonant instability associated with a ∼ 40 keV ion beam.By an extrapolation of the results presented here, assuming microflares and nanoflares at the Sun generate shocks in the lower corona and these shocks accelerate energetic ions, we suggest that the ions, via the right‐hand resonant instability, generate magnetosonic waves which steepened to form “microshocks” (such as shown here). These shocks could, in turn, accelerate more energetic ions, leading to a shock/energetic ion/magnetosonic wave cascade. These newly formed magnetosonic waves and shocks presumably could propagate in a broad range of directions, leading to energy dissipation over a large region of the outer corona.
Static compressibility of magnesite to 20 GPa: Implications for MgCO3 in the lower mantle
Authors: Redfern S. A. T. , Wood B. J. , Henderson C. M. B. 
Published: February 2008

The bulk modulus of MgCO3 magnesite has been measured to 20 GPa at room temperature using X‐ray powder diffraction. Since the response to pressure is primarily compression of the MO6 octahedron, magnesite is substantially less compressible than Ca‐carbonates of similar structure type. Using the Birch equation of state, with KT′ of 4.0, we obtain KT of 142 (±9) GPa at room temperature. The full Birch‐Murnaghan equation of state yields KT of 151 (±7) GPa and KT′ of 2.5.These results, together with other thermodynamic data, have been applied to calculate the stability of magnesite under lower mantle conditions. Assuming lower‐mantle saturation in (Mg,Fe)O, magnesite should be stable to temperatures well in excess of 6000 K at the core‐mantle boundary, i.e. at least up to the solidus of peridotitic or pyroxenitic compositions. This confirms that magnesite is a stable host for carbon in the mantle.
Latitudinal profiles of stratospheric water vapor
Authors: Kuhn P. M. , Stearns L. P. , Lojko M. S. 
Published: February 2008

Water vapor burden and in situ mixing ratios above and at high altitude flight levels were inferred from observations in the rotational water vapor spectral band (19.0–35.0 µm). Flight levels ranged from 15.3 to 20.0 km during 12 meridional traverses of a W‐B57‐F jet. The method of radiance observation, while radiometric, involved emission observations rather than absorption spectra analyses employed by McKinnon and Morewood [1971]. The flights made during September, October, November 1973 and January 1974 provide profiles of lower stratospheric water vapor by overlapping tracks from 50°S latitude to 75°N latitude.The objective of the research is to describe the method of recovery of the water vapor burden and in situ mixing ratio by inference from infrared emission observations and to present the results as a latitudinal profile.
The mechanism for ultraviolet photolysis of gaseous chlorine nitrate at 302.5 nm
Authors: Smith W. S. , Chou C. C. , Rowland F. S. 
Published: February 2008

The laboratory photolysis of chlorine nitrate (ClONO2) with 302.5 nm ultraviolet light leads to the destruction per quantum of 4 molecules of ClONO2 and the formation of 1 molecule of O2, 2 of Cl2 and 2 of N2O5. These quantum yields are not consistent with the current assumption that the primary photolysis step for ClONO2 in the stratosphere leads to the formation of ClO plus NO2. A consistent mechanism exists in which the photolytic step involves the decomposition of ClONO2 to ClONO + O(³P). The onset of observed absorption of radiation by ClONO2 corresponds approximately to the thermodynamic accessibility of this simple splitting away of an O atom.The photolysis of ClONO occurs very rapidly in the stratosphere, either to Cl + NO2 or ClO + NO. The substitution of either Cl + NO2 + O or ClO + NO + O for ClO + NO2 as the eventual photolysis products from ClONO2 is not expected to cause appreciable alteration in predictions from stratospheric modeling.
A balloon borne instrument to induce corona currents as a measure of electric fields in thunderclouds
Authors: Weber M. E. , Few A. A. 
Published: February 2008

A device for measuring the point discharge emitted from a 2m length of copper wire, using a radiosonde as carrier platform, has been developed in order to measure the distribution of charged regions inside thunderclouds with respect to temperature and altitude. No modifications to the radiosonde or in its standard receiving equipment are required.In four penetrations of electrified clouds over central New Mexico, corona currents were induced in the conducting wire. The measurements were characterized by reversals in the polarity of the current which can be interpreted as a result of the balloon's rising past the level at which charge of one sign is concentrated.
Secular variation of gravity in Mexico?
Authors: Singh S. K. , Mena M. , Monges J. 
Published: February 2008

Based on data obtained during the period 1949‐1967, Woollard and others reported large secular variation of gravity in Mexico. Data obtained since 1971, using LaCoste‐Romberg gravimeters, indicate that no significant variation is occurring between Mexico City and Acapulco and Monterrey and Mexico City at present. Local secular variation of gravity reported for Mexico City is continuing and is well correlated with the sinking (due to water withdrawal) of the city.This article contains supplementary material.
Whistler propagation in the Jovian magnetosphere
Authors: Menietti J. D. , Gurnett D. A. 
Published: February 2008

Computer ray tracing results are presented for lightning generated whistlers propagating in the Jovian Magnetosphere. The waves are launched from a point on the Jovian surface at 66° latitude and propagate approximately along L = 6 out to near the equatorial plane and into the Io plasma torus. The magnetospheric model includes the Io torus centered at the magnetic equator. The torus model is an empirical fit of the density contours presented by Warwick et al. [1979], and the electron density outside of the torus is an adaptation from Sentman and Goertz [1977]. The results clearly indicate that the whistlers propagate through the magnetosphere with very little dispersion until reaching the torus, at which time the dispersion starts to increase very rapidly. We find that the computed dispersions using the assumed electron density model are in excellent agreement with the observed whistler dispersions, thereby confirming the validity of the model.In addition to the ray path studies, the effect of Landau damping on whistler waves has been investigated as a function of the electron temperature within the torus. For a constant electron temperature of 105°K only the lowest frequencies, ≲1.0 kHz, show appreciable attenuation after passing through the torus. But an increase in the electron temperature of only a factor of three results in a very large attenuation over the entire frequency range observed. This result suggests an upper limit for the electron temperature in the torus of a few times 105°K.
Measurements of long delayed radio echoes in the auroral zone
Authors: Freyman Robert W. 
Published: February 2008

A high‐latitude, earth‐based high‐frequency (9.9MHz) radiowave backscatter technique for the real‐time detection of Long Delayed Echoes was tested at College, Alaska. Over 2000 apparent LDE were detected and recorded from 15 to 22 July, 1980.A positive correlation was obtained between the number of reflections per unit time and the probable entry of enhanced solar plasma into the magnetosphere and/or local disturbed magnetic conditions. The modes and paths by which the signals propagate are yet to be established. However, regardless of their origin, the echoes seem to be genuine and these observations are therefore unique in the study of LDE radiowave propagation phenomenology.
Experience with in situ measurement of rock deformability
Authors: Bieniawski Z. T. 
Published: February 2008

Although in situ tests have the advantage of involving a large volume or rock tested under the same environmental conditions as are prevailing in the rock mass, such tests are expensive and time consuming. In addition, there are a number of controversial questions pertinent to in situ tests.This presentation discusses the first‐hand experience with three in situ test methods. These are: (i) plate bearing tests, (ii) large and small flat jack tests, and (iii) Goodman jack tests. By identifying the problems associated with in situ testing, useful lessons can be learned for large scale laboratory testing in geomechanics.
Lidar observations of volcanic clouds in the stratosphere over Fukuoka, caused by eruptions of Mt. St. Helens in May 1980
Authors: Hirono M. , Fujiwara M. , Shibata T. , Kugumiya N. 
Published: February 2008

A sudden increase of stratospheric aerosols has been observed by a Nd‐YAG lidar at the wavelengths 1.064 µm (F) and 0.532 µm (S) since June 4th, 1980 (all times JST = GMT +9). The increase is thought to be caused by the eruption of Mt. St. Helens in May, 1980. The initial increase began at an altitude of about 15km and the scattering ratio at wavelength F reached a maximum on June 5th. This indicates that the aerosol mixing ratio is about 70 times the non‐volcanic ratio at the same altitude. The extinction of the vertically incident direct solar radiation has been calculated to be 2 × 10−2 on the average for June and July, which is 4.6 and 3 times the non‐volcanic value, respectively, for the fall of 1979.After examination of the size distribution of aerosols inferred from a comparison of profiles at the F and S wavelengths and data by other measurements, it may be concluded that our lidar has seen relative temporal and spatial variations of the aerosols fairly well, but underestimated their absolute magnitude due to the assumption of clean air near 30km. A method for correcting the underestimation would increase the extinction by a factor of 1.4 ‐ 2.0. This method is described and global distribution of aerosol inventory estimated on the basis of a two dimensional analysis.
Application of dipole modeling to magnetic anomalies
Authors: Schmitz Dave , Frayser J. B. , Cain Joseph C. 
Published: February 2008

A least‐squares technique is developed to obtain dipoles, which, when combined with an existing global field model, represent the relatively isolated magnetic anomalies which are residual to the high order (greater than 20) spherical harmonic internal geomagnetic field model. This combination of models (global spherical harmonic and local dipole) forms an efficient and compact representation of the geomagnetic field. The technique involves simultaneously solving for all three components of moment and of position of a dipole.The technique is applied to the mega‐anomaly west of Australia in a region about Broken Ridge, using data and spherical harmonic models separately constructed from POGO and MAGSAT spacecraft. The resulting equivalent dipoles agree fairly well and may be averaged to a 1 T·km³ dipole buried at 60 to 70 km depth near 32°S, 97°E oriented horizontally with a small (3±3°) east declination.This article contains supplementary material.
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.
New in‐situ measurements of the absorption cross‐sections of O2 in the Herzberg Continuum
Authors: Pirre Michel , Rigaud Pierre , Huguenin Daniel 
Published: February 2008

The absorption cross‐sections of both O2, from 200 to 220 nm, and O3 from 220 to 235 nm have been deduced from measurements of the atmospheric absorption performed at night aboard a stratospheric balloon launched from Aire sur 1'Adour (France)The ozone column content was previously determined using the absorption measured from 278 to 289 nm, assuming that the ozone absorption cross sections are well known in this wavelength interval. The O2 and O3 cross sections have been found to meet most of the laboratory measurements. From 200 to 210 nm the results concerning the O2 cross‐sections do not confirm the low values measured recently in the stratosphere and in the laboratory.
Wave activity in the neighborhood of the bowshock of Mars
Authors: Sagdeev R. Z. , Shapiro V. D. , Shevchenko V. I. , Zacharov A. , Király P. , Szegó K. , Nagy A. F. , Grard R. J. L. 
Published: February 2008

Plasma wave activity in the neighborhood of the Martian bow shock were measured for the first time by the Soviet spacecraft Phobos‐2 in a wide frequency range from dc to 150 kHz. The wave activity varied in character as the spacecraft moved across different plasma regions: in the neigborhood of the Martian bow shock, inside the magnetosheath and in the tail region.In this paper we provide suggestions for the processes responsible for these plasma waves. The most interesting peculiarities of the wave activity around Mars is the sharp increse of wave intensity in the magnetosheath region. This increase is attributed to two different physical mechanisms. High frequency waves are excited at the shock front due to currents flowing along the front; these ion acoustic waves are convected inside by the solar wind. The low frequency waves (∼100 Hz) close to the inside boundary were, we believe, generated by heavy Martian ions diffusing through the planetopause into the magnetosheath.
Polar cap plasma flow entry region
Authors: Primdahl F. , Primdahl I. S. , Spangslev F. 
Published: February 2008

In an earlier paper [Primdahl et al, 1980] we presented the daily distribution for the slant E condition (SEC) occurrences seen on ionograms from Thule (86° invariant latitude), from Godhavn (77.5° invariant latitude), and from Narssarssuaq (68° invariant latitude). The data was divided into two groups: one for A days and one for T days corresponding on the average to IMF By >0 and IMF By <0, respectively.At Thule the distribution shifted toward morning hours on A days and toward afternoon hours on T days, in accordance with the expectation that SEC should follow the region of high plasma flow velocity and thus the region of high electric field. (For further discussion see the reference).
Ray tracing in the Io plasma torus: Application to the PRA observations during Voyager 1's closest approach
Authors: Lecacheux Alain 
Published: February 2008

An attempt is made to simulate propagation of the low‐frequency radio waves in the vicinity of the Io plasma torus near Jupiter. In absence of a definitive and detailed electron density model for this torus, a number of minimal hypotheses were used. Nevertheless, the anomalous radio dynamic spectrum observed during the day of Voyager 1's closest approach could agree with an emission source situated around the planet in the southern hemisphere and related to the local gyrofrequency.The major conclusion is that the entire low frequency (up to a few megahertz) dynamic radio spectrum of Jupiter could be modified by refraction inside and around the Io torus. The magnitude of the effects depends on the location of the source and on the plasma parameters distribution inside the torus.
Statistics for the one‐norm misfit measure
Authors: Parker Robert L. , McNutt Marcia K. 
Published: February 2008

Confidence tables and other parameters are provided for a misfit statistic based upon the sum of the absolute discrepancies between a model and observation. This one‐norm misfit is compatible with the application of linear programing in geophysical modeling, a technique of considerable value when inequality constraints are to be applied in the mathematical model.Tables are available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Ave., N.W., Washington, D.C. 20009. Document J80‐009; $1.00. Payment must accompany order.
A direct measurement of the distance between a hypocenter in a Benioff‐Wadati Zone and the Slab‐Asthenosphere contact
Authors: Stefani Joseph P. , Geller Robert J. , Kroeger Glenn C. 
Published: February 2008

We made a direct measurement of the distance from a hypocenter in the Benioff‐Wadati zone to the boundary between the downgoing slab and overlying asthenosphere. This was accomplished by identifying a low amplitude P wave reflection off the slab‐asthenosphere contact which arrives at teleseismic stations several seconds after the initial P arrival. The measured delay time (after P) of the reflected phase shows a consistent azimuthal variation, thus eliminating possible source or receiver effects. The relative amplitude, polarity, and delay time of this observed phase are consistent with a model in which the distance between hypocenter and slab‐asthenosphere contact at this depth is about 38±5 km. The event studied was an intermediate depth (181 km) earthquake in the southern Kuriles which occurred in the lower layer of a double seismic zone. Our measured distance, when compared to the distance between the two seismic zones, indicates that the upper layer of seismicity is within 15 km of the slab‐asthenosphere contact.Appendix is available with entire article, on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, U.C. 20009. Document JB1‐010; $1.00. Payment must accompany order.
Introduction to Special Section on How Volcanoes Work: Part 3
Authors: Tilling Robert I. 
Published: February 2008

The nine papers in this issue represent the third, and final, part of the special section on “How Volcanoes Work.” Part 1 of this special section was published in the December 1987 [Tilling, 1987] and part 2 in May 1988 [Tilling, 1988] all three parts will be published together as a separate volume titled “How Volcanoes Work” by the American Geophysical Union. In its entirety, the special section gives a good sampling of the nearly 300 papers presented at an international symposium of the same name held in Hilo, Hawaii, in January 1987 in commemoration of the Diamond Jubilee (75th Anniversary) of the founding of the Hawaiian Volcano Observatory [Wright and Decker, 1987].The breadth of topics covered in all three parts of the special section (Table 1) amply attests to the multidisciplinary nature of modern studies of volcanic phenomena. Collectively, these studies also comprise a most fitting tribute to Thomas A. Jaggar, Jr., who founded the Hawaiian Volcano Observatory in 1912 and was a dominant force in quantifying the science of volcanology. Not only was Jaggar a scientific visionary, but he also stressed that the scientific knowledge on volcanoes must be applied to reduce death and destruction from volcanic hazards. It is clear from the papers contained in the special section of the Journal of Geophysical Research that great strides have been made in our scientific understanding of how volcanoes work since Jaggar's time. But the destructive eruptions at Mount St. Helens (United States, May 1980), E1 Chichón (Mexico, March–April 1982), and Nevado del Ruiz (Colombia, November 1985), each causing the worst volcanic disaster in the recorded history of each of these countries [Tilling and Newhall, 1987] are tragic reminders that commensurate advances in reducing volcanic risk on a global basis have not yet been achieved.