bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to the report on geodesy
Authors: Williams Owen W.
Published: February 2008

The achievements of the U.S. geodetic community during the years 1974–1978 between the General Assemblies of the IUGG are summarized in this section. During this quadrennium, American geodesy dramatically moved from the era of primarily meeting the traditional needs of surveying and mapping into one of supporting a broad spectrum of geophysical and planetary disciplines. This movement was aided by modern technology epitomized by the increases in Doppler satellite observations, multifrequency distance measurements, lunar and satellite laser ranging, very long base line interferometry (VLBI), satellite altimetry measurements and inertial positioning.

By far the most spectacular achievement in the field of geodesy during this period was the global sampling of sea surface topography with precision radar altimeters aboard the National Aeronautics and Space Administration (NASA) GEOS‐3 and Seasat‐1 satellites. The GEOS‐3 altimetry data set, acquired over a 3‐year period (1975–78), significantly improved our knowledge of the global gravity field of the earth, the oceanic geoid and the related mean gravity anomalies. Had the Seasat‐1 not failed after 3 months, an even more detailed knowledge of the oceanic geoid would be available today. Even with this early demise, Seasat‐1 in 3 months collected more altimetry data with greater accuracy than did GEOS‐3 in 3 years.
Satellite altimetry
Authors: Stanley H. Ray
Published: February 2008

Since the last national report to the sixteenth General Assembly, research activities in the development of appropriate techniques and the direct application of altimeter data have moved rapidly from the launch of the SKYLAB S‐193 Experiment in 1973 through the GEOS‐3 launched in June 1975 to the SEASAT‐1 launched in June 1978. GEOS‐3 is still providing some data, SEASAT‐1 ceased functioning on October 9, 1978. The basic satellite altimetry concept involves vertical measurements to the nadir surface from an orbiting platform. Although highly dependent upon the characteristics of the instrumentation and the orbiting platform, these vertical measurements contain information concerning the distance to the surface, the scattering properties of the surface, and the condition of the transmission medium. The plan of this review is to show the present status of the instrumentation and to discuss the applications of and near‐term prospects for the altimeter and altimeter data.
Thermodynamics and lattice vibrations of minerals: 4. Application to chain and sheet silicates and orthosilicates
Authors: Kieffer Susan Werner
Published: February 2008

This paper is the fourth in a series relating the lattice vibrational properties to the thermodynamic properties of minerals. The temperature dependence of the harmonic lattice heat capacity is calculated from a model which uses only elastic, crystallographic, and spectroscopic data for the following minerals: calcite, zircon, forsterite, grossular, pyrope, almandine, spessartine, andradite, kyanite, andalusite, sillimanite, clinoenstatite, orthoenstatite, jadeite, diopside, tremolite, talc, and muscovite. The heat capacities of these minerals reflect structural and compositional differences. The ‘excess’ entropy of pyrope—compared with that of grossular—is shown to arise from low‐frequency optic modes of vibration. The entropy differences between kyanite, andalusite, and sillimanite are well reproduced by the model, although the absolute values calculated are systematically about 3% high. Model values of the heat capacity and entropy are compared with experimental values at 298.15, 700, and 1000°K for the 32 minerals included in papers 1–4 of this series. The average deviation of the entropies at 298°K from well‐determined calorimetric values is ±1.5%. A method is given for obtaining greater accuracy in the model thermodynamic functions by fitting one parameter to experimental data when partial calorimetric data (such as the heat capacity at a single temperature in the range 50–100°K) are available; such a method should permit accurate extrapolation of calorimetric data beyond the range of experiment.
Planetary geodesy
Authors: Sjogren William L.
Published: February 2008

This report, which follows the general format of reports by J. D. Anderson [1975] and W. H. Michael [1979], deals with geodetic parameters of the planets and their satellites (including the Moon but not the Earth): shape, rotation, orientation, and gravity. A paper by Ferrari and Bills [1979] covers similar material as Michael [1979], but contains additional comments on geophysics. Three review articles, which provided a helpful base for the references reported here, are Harris and Ward [1982], Phillips and Lambeck [1980], and Balmino [1981]. A very basic document covering all planetary bodies and their satellites is the report of the International Astronomical Union Working Group [Davies, et al, 1982], which provides new values for cartographic coordinates, orientations, and rotations.
Convection
Authors: Boss Alan Paul
Published: February 2008

Convective motions must be responsible for transporting essentially all the thermal energy from the interior of the earth to the surface layers of the planet. This thermal energy is derived from sources such as radioactive decay, cooling of the planet, and from the release of gravitational energy associated with growth and differentiation of the core. While the very presence of plate tectonics on earth is often considered prima facie evidence for at least upper mantle convection, the motion of the lithospheric plates on the surface of the earth also gives an indication of the patterns of convection in the underlying layers of the mantle.

Convective motions are difficult to rigorously model in general because of the three dimensional, time dependent, multiple scale, nonlinear nature of the flows involved, and the complex rheology of the matter itself. Thus, while it is relatively easy to construct simplified models for how the Convective motions may be occurring on a global scale, or even detailed models of small‐scale phenomena, a rigorous, global model of the Convective processes in the earth's mantle and core, at the present time as well as throughout its evolution, consistent with the constraints imposed by geophysics, geochemistry, and dynamical modeling, does not exist. This deficiency is the fundamental problem that motivates much of the work on convection reviewed in this paper.
Wüstite (Fe1‐x O): A review of its defect structure and physical properties
Authors: Hazen Robert M. , Jeanloz Raymond
Published: February 2008

Wüstite is a complex nonstoichiometric oxide of iron with the general structural formula VI[Fe2+ 1−3xFe3+ 2x−t □x+t]IVFe3+ tO where 0.04 < x < 0.12 and 2.0 < (x + t)/t < 4.5. Wüstites of a given bulk composition exist in a variety of structure types characterized by differing ratios of octahedral to tetrahedral ferric iron and by differing degrees of long‐ and short‐range order of clustered defects. In addition, most, if not all, wüstites have exsolved magnetite or iron lamellae on the scale of several tens of unit cells. Though wüstite is compositionally intermediate between pure FeO and magnetite, wüstite is not structurally intermediate and thus does not represent a solid solution between the two stoichiometric iron oxides. Physical properties of wüstite, including cation diffusion, electrical conductivity, and magnetic properties, are dependent on defect structure type and exsolution, as well as degree of nonstoichiometry. Simple linear relationships between stoichiometry and molar volume or between stoichiometry and bulk modulus, for example, do not obtain. Experimental studies on wüstite should include data on conditions of synthesis, as well as details on the structural state before and also after the experiments.
On the variability of the net longwave radiation at the ocean surface
Authors: Fung Inez Y. , Harrison D. E. , Lacis Andrew A.
Published: February 2008

The bulk formulae (BF) commonly used to estimate the net longwave radiation at the ocean surface (LW⇅) often give dissimilar results for given surface parameters. Because the differences are climatologically significant amounts of energy, it is important to understand the sources of these differences. We present an evaluation of the most widely used BF, in terms of the assumptions made in each, the climatic conditions on which each is based, and on the results of each compared with results computed from the full radiative transfer equation (RTE) with zonally averaged atmospheric data. The differences can best be understood through examination, using the RTE as the basic tool, of the variability of LW⇅ to variations in temperature, humidity, and cloud properties in the atmospheric column as well as at the surface. These calculations reveal that under clear sky conditions, two standard deviation perturbations of either temperature or specific humidity in the atmospheric column above the surface layer can introduce LW⇅, variations of 30–40 W/m². These variations, which would be typical of the synoptic variations of LW⇅ resulting from typical atmospheric variability, are generally greater than the differences produced by using different BF for the same surface conditions. Although the differences between BF LW⇅ and RTE LW⇅ can be large, the results from the Berliand and Anderson formulae duplicate the RTE clear sky LW⇅ to ±15 W/m² under a wide range of mean and perturbed conditions. The RTE studies also reveal that LW⇅ variations due to cloudiness effects can be very large. Low clouds can reduce LW⇅ from clear sky values by as much as 70 W/m². There is strong dependence of LW⇅ on the vertical distribution of cloud properties which renders useless, for estimating instantaneous LW⇅ under cloudy skies, the BF which do not carefully distinguish between cloud types. The accuracy of BF for climatological applications cannot be assessed without information about the geographic and temporal distributions of cloud properties. The computed sensitivity of LW⇅ to variations in the atmospheric column illustrates the type of information and the level of accuracy necessary to attain a particular level of accuracy in LW⇅. Improved remote sensing techniques and improved information about the cloud distribution statistics will lead to better estimates of LW⇅ at the ocean surface and a more realistic parameterization of cloud effects in BF.
Calculating the surface energy balance for lake and reservoir modeling: A review
Authors: Henderson‐Sellers B.
Published: February 2008

The surface energy balance (SEB) of a freshwater body must incorporate shortwave (solar) and long‐wave (terrestrial) radiation, together with evaporation and sensible heat energy fluxes. For inclusion in a prognostic water quality model it is vital to be able to calculate, rather than measure, these energy terms and to relate them to routinely observed meteorological parameters such as air temperature and cloud cover. Here various formulae are analyzed and compared by using two climatologically different data bases. For shortwave radiation the formulae recommended for use, in the dearth of local observations, are those of Prescott (1940) (for temporal scales of weeks or months) and Tucker (1982) (for shorter time scales). The shortwave albedo can be given by the parametrization of Pivovarov (1972), the incoming long‐wave atmospheric radiation by a blackbody representation modified by an effective atmospheric emissivity (Raphael, 1962), and the evaporative flux by the equation of Sill (1983), with the sensible heat flux being related to the evaporative energy flux via the Bowen ratio under conditions of neutral atmospheric stability.
Precipitation analysis, modeling, and prediction in hydrology
Authors: Georgakakos Konstantine P. , Kavvas M. Levent
Published: February 2008

In recent years U.S. meteorologists and hydrologists have shown increased interest in research related to modeling, observation and prediction (forecasting) of precipitation. In particular, mesoscale precipitation research has received most of the researchers' attention. This is mainly because of the following three reasons:

1) There has been a shift of interest in the Atmospheric Sciences from the large scale to the mesoscale with emphasis in improving precipitation prediction (e.g., National Academies, Committee on Science, Engineering, and Public Policy, 1985; National Research Council, Ad Hoc Panel on Mesoscale Processes, 1981; National Research Council, Panel on Precipitation Processes, 1980; Court, 1979).
Operational numerical weather prediction
Authors: Brown John A.
Published: February 2008

A variety of analysis and forecast systems have been used routinely over the years to produce numerical weather predictions (NWP) for daily use. The Joint Numerical Weather Prediction Unit of the United States was the first operational organization established in 1955. Since then, a large number of NWP centers have evolved in the industralized nations of the world. Today their predictions serve as the primary guidance for practicing synopticians for the forecast period from about 12 hours out to 10 days.
Meteorological applications of lightning data
Authors: Orville Richard E.
Published: February 2008

The significance of the meteorological applications of lightning data is that in recent years we have acquired the technology to use the observations of lightning in many areas of operational meteorology. Consider the past for a moment. In the 1940's, we began to observe the characteristics of cloud systems with radar; in the 1960's, we observed them with satellites in the visible and infrared wavelengths; and in the 1970's and 1980's, we developed the techniques to monitor lightning activity from satellites and to detect the lightning to ground from cloud systems using ground based lightning detection networks. The combination of radar, satellite, and lightning observations of weather systems has opened a new area of applied meteorology that is attracting the interest of both the research and the operational meteorologist.
The influence of clouds on radiation: A climate‐modeling perspective
Authors: Fouquart Y. , Buriez J. C. , Herman M. , Kandel R. S.
Published: February 2008

The influence of clouds on the radiation field is reviewed from the point of view of their representation in climate models. Such models are expected to include, in the very near future, condensed water as an additional prognostic variable. We examine how simple parameterizations based on the liquid water content can realistically simulate the radiation field. We focus on the extended low‐level clouds for which numerous results of simultaneous radiation and microphysics measurements are available. Particular attention is given to the shortwave absorption in cloud layers because theoretically calculated absorptances are generally weaker than those observed. The problem of the broken field is approached in terms of a relationship between the actual cloud cover and the equivalent cloud cover which gives the same irradiances but using the plane‐parallel formalism.
Application of Auger Electron Spectroscopy to studies of chemical weathering
Authors: Mogk David W.
Published: February 2008

Auger electron spectroscopy (AES) is a surface‐sensitive analytical technique that derives from the interaction of an electron beam and atoms in residence at the surface of a sample; inner shell ionizations produce Auger electrons, which have an escape depth of only a few tens of angstroms. This technique has numerous applications to chemical weathering and other geochemical processes that operate on mineral surfaces. The analytical capabilities of AES include chemical analyses of the near surfaces of minerals for all elements except H and He, semiquantitative analysis of the relative atomic concentration of surface components, high lateral spatial resolution (>0.1 µm) of the analyzed area to determine the composition of discrete domains on mineral surfaces and to identify unknown minerals on a submicrometer scale, and elemental depth profiling using an ion sputter gun. These capabilities can be used to address the nature of mineral dissolution processes, providing discrimination among mechanisms such as congruent versus incongruent dissolution, surface‐controlled reactions versus diffusion through a leached or armored layer, uniform versus heterogeneous distribution of reacted layers, and identification of alteration phases. The effectiveness of AES analysis is limited by charging of nonconducting samples (e.g., silicate minerals) and sample degradation under the electron beam; these problems may be mitigated by careful sample preparation and instrument operation procedures. AES can be used in concert with numerous other microbeam techniques to fully characterize the surface composition and structure of reacting minerals.
A Pseudodynamic Programming Technique for the Design of Correlator Supersynthesis Arrays
Authors: Mathur N. C.
Published: February 2008

A correlator supersynthesis array is defined as an array of antennas connected together in pairs as interferometers and capable of tracking a radio source during its apparent motion in the sky. Some problems in the design of such arrays are discussed. A computerized optimization technique, termed pseudodynamic programming, is described for the design of such arrays and some results are presented. The limitations and capabilities of the technique are discussed.
Reflection and Transmission by a Random Medium
Authors: Kupiec I. , Felsen L. B. , Rosenbaum S. , Keller J. B. , Chow P.
Published: February 2008

The mean field is considered for a bounded medium with a refractive index having a real random part. It has been shown previously that for suitable ranges of the amplitude and correlation length of the refractive index fluctuations, this field satisfies a certain integrodifferential equation. This equation is solved for a plane wave incident from either side on the plane boundary of a semi‐infinite random medium, for the Green's function of a semi‐infinite random medium, and for a plane wave incident on a slab of random medium, provided that the background refractive index is homogeneous throughout. The cases of both one‐ and three‐dimensional fluctuations are considered, and explicit expressions are given for the reflection,transmission, and coupling coefficients for a medium with an exponential correlation function.A Wiener‐Hopf factorization required for other correlation functions is described, as are methods for treating reflection and transmission at a curved boundary of a random medium. A principal finding is the inadequacy of treating the mean wave in a bounded random medium by using just the refractive index for an unbounded random medium, for in addition we must include a transition layer near the boundary.
Radar Backscattering from the Turbulent Clear Atmosphere
Authors: Ottersten Hans
Published: February 2008

Radar backscattering from the turbulent clear atmosphere is caused by irregular small‐scale fluctuations in the radio refractive index produced by turbulent mixing. This note considers the theoretical relationships between the refractive‐index microstructure and the back‐scattering at radar wavelengths from meters to centimeters. Spectral relationships are clarified and the basic difference between radar sampling and refractometer sampling of refractivity spectra is explained. Theoretical expressions are given for the relationship between the radar reflectivity and spectral representations of the refractive‐index variability for the general case, for the isotropic case, and for the inertial subrange.
The Structure of Venus Clouds—Summary
Authors: Rasool S. I.
Published: February 2008

The analysis of the Mariner‐5 radio occultation data has resulted in significant new information on the structure of cloud layers in the lower atmosphere of Venus. Figure 1 shows the Mariner‐5 signal attenuation as a function of altitude recorded during the occultation experiment. The solid line marked ‘CO2 defocusing’ shows the anticipated attenuation calculated with the assumption that the atmosphere is mainly composed of CO2 and that the atmospheric defocusing is the only cause of attenuation. The observational curve in the figure differs from the calculated curve in two respects: (1) the observed attenuation is considerably greater than that anticipated at altitudes below 52 km; and (2) although the theoretical curve is smooth, the measured attenuation shows a structure with sharp changes in slope and several peaks.
Remote sensing of the turbulence characteristics of a planetary atmosphere by radio occultation of a space probe
Authors: Woo Richard , Ishimaru Akira
Published: February 2008

The purpose of this paper is to analyze the effects of small‐scale turbulence on radio waves propagating through a planetary atmosphere. The analysis provides a technique for inferring the turbulence characteristics of a planetary atmosphere from the radio signals received from a spacecraft as it is occulted by the planet. The planetary turbulence is assumed to be localized and smoothly varying with the structure constant varying exponentially with altitude. Rytov's method is used to derive the variance of log‐amplitude and phase fluctuations of a wave propagating through the atmosphere. When the distance between the spacecraft and the planetary atmosphere exceeds L02/λ, where L0 is the outer scale of turbulence, the effects of inhomogeneity and finite size of the turbulent medium become important. A recent study by Gurvich [1969] pointed out that the structure constant for the Venusian atmosphere inferred from the Mariner‐5 occultation data was significantly lower than that inferred from the Venera‐4 data. By applying the analysis developed in this paper it is shown that the effects of inhomogeneity and finite size of the turbulence, which were excluded in Gurvich's analysis, account for this difference. More important, however, is the fact that the new techniques are available for use in future radio‐occultation missions.
Reflection and transmission of electromagnetic waves at a moving magnetoplasma half‐space
Authors: Mukherjee P. K. , Talwar S. P.
Published: February 2008

The interaction of an electromagnetic wave with a plane interface between a stationary isotropic medium (dielectric or vacuum) and a homogeneous cold magnetized plasma moving uniformly parallel to the interface is considered for arbitrary angles of incidence. Calculations are presented for the case in which the static magnetic field lies in the interface and is oriented normal to both the plane of incidence and the direction of the streaming motion. It is found that the reflection and the transmission characteristics for an incident E wave are unaffected by the anisotropy and the velocity of the moving medium. Numerical results for the reflection and the transmission coefficients for an obliquely incident H wave have been obtained for several values of the magnetic field and the electron density of the moving plasma half‐space. It is found that the moving magnetized plasma medium allows certain stop and pass bands under suitable physical conditions.
Pulse compression systems for use with meteorological radars
Authors: Austin G. L.
Published: February 2008

The theory of pulse compression systems for extended precipitation targets is reviewed referring specifically to a 13:1 phase‐coded compression system currently in use. The expected loss in sensitivity of a factor b, the compression ratio, is obtained compared with b2, obtained by transmitting shorter pulses. The effects of the range sidelobes in smoothing out steep gradients of reflectivity are examined. It is concluded that they are serious but not prohibitive.
The French quadristatic incoherent scatter facility
Authors: Bauer P. , Waldteufel P. , Vialle C.
Published: February 2008

The original Nançay‐St. Santin incoherent scatter facility based on the radio astronomy antenna at Nançay and a CW transmitter located at St. Santin (300 km south) was improved in many ways between 1965 and 1970: doubling of the transmitted power to 140 kw, lowering of the receiver noise level down to 100 K, monitoring of the antenna and data acquisition through the use of a computer, rejection of the parasitic tropospheric echoes.

However, the most important improvement brought to the system is the addition of two new receiving stations 100 km east and west of the transmitter. Each of the new stations is equipped with a three‐beam Cassegrain antenna (25‐m parabola) aimed to simultaneously intersect the vertical transmitted beam at three different heights. Both new receivers have wide band (38 MHz at 3 db) gaseous helium cooled parametric amplifiers and on‐line computers. While one of the two new stations is equipped with filter banks for the purpose of spectral analysis, a different choice has been made for the other station. For the latter the data acquisition will imply multibit correlators, for both the ionic spectrum and plasma line measurements.

Most of the improved electronic equipment designed for the new stations has also been implemented in the Nançay receiver. The frequency and time synchronization between the four sites is now accomplished by employing a single 5‐MHz frequency standard in each station monitored by standard time and frequency signals from MSF and/or HBG stations.

The observation procedure consists of tilting the different receiving antennas so as to gather the signal scattered from the ionospheric vertical column illuminated by the transmitter. For calibration purposes a standard ionosonde is operating at St. Santin.

The main objective of the quadristatic system is to determine completely the ion drift vector in order to study the electric fields and the neutral tidal winds. Other capabilities offered by the new system are a determination of the plasma line and a higher data acquisition rate.

The first observations with one of the new stations were performed in December 1972.
Analysis of experimental NRL radar altimeter data
Authors: Walsh Edward J.
Published: February 2008

An X‐band radar designed and built by the Naval Research Laboratory and capable of continuously variable transmitted pulse durations down to 1 nsec is being flown on a NASA Wallops Flight Center C‐54 aircraft to investigate the interaction of radar altimeter signals with the sea surface. There is good agreement between the observed radar altimeter leading edge rise time for a 1‐nsec transmitted pulse and the rise time predicted from the radar parameters and the sea state determined by a laser profilometer. Using a threshold tracker on 29‐pulse averages for a transmitted pulse of 24 nsec, we found that the range noise varied linearly with the power level of the threshold over a considerable range. The altimeter range quantization was 9.35 cm and a minimum range noise of 3.9 cm was obtained. A comparison of pulse‐to‐pulse correlation observed in the radar data with that predicted by a Monte Carlo simulation is used to obtain a measure of sea surface scatterer motion.
Fetch and wind speed dependence of Doppler spectra
Authors: Duncan J. R. , Keller W. C. , Wright J. W.
Published: February 2008

Previous measurements of Doppler spectra in microwave backscattering in a wind wave tank at 9.375 GHz and 23.9 GHz have been extended to 70.1 GHz at 3 m fetch and to longer fetches and higher winds at the two lower microwave frequencies. At high depression angles, the scatterers appear to be specular points moving at approximately the speed of the dominant wind wave. At lower depression angles, the scatterers can be thought of as comprising systems which are respectively bound to and free of the dominant wave. The free scatterers are low‐order Bragg scatterers and it is natural to treat them as free waves or free wave systems in their own right. The bound scatterers are the familiar parasitic capillary waves at low winds, but at higher winds they appear to be associated with the breaking water at the crest of the dominant wave.
A theoretical model for short‐scale field‐aligned plasma density striations
Authors: Perkins Francis W.
Published: February 2008

The short‐scale (about 3 m), field‐aligned plasma density striations found in ionospheric modification experiments are generated by the plasma turbulence resulting from ion acoustic‐plasma wave parametric decay instabilities. The field‐aligned geometry results from the fact that nonlinear wave coupling arises from thermal, ohmic heating terms rather than ponderomotive force (radiation pressure). The theory shows that field‐aligned striations increase rapidly in intensity as the wavelength increases—in agreement with experiment.
Mean speeds of wind waves at short fetch
Authors: Keller W. C. , Larson T. R. , Wright J. W.
Published: February 2008

The mean speeds of short wavelength wind‐generated waves (wavelengths less than 4 cm) have been obtained from Doppler spectra measured at very short fetch in a wave tank for wind speeds up to 15 m sec−1. These speeds are compared with phase speeds calculated from a first‐order perturbation of the wind drift and reasonable agreement is obtained. The measurements show that the difference between mean wave speed and the mean surface drift becomes quite small for wind speeds exceeding 12 m sec−1.
Fields of an electric line source parallel to an inhomogeneous dielectric layer with critical‐coupling regions
Authors: Bahar E. , Govindarajan G. , Agrawal B. S.
Published: February 2008

A characteristic surface impedance for an inhomogeneous dielectric slab that critically couples forward and backward travelling waves is computed using a generalized WKB method. The characteristic surface impedance, which is the tangential electric to magnetic field ratio at the surface of the slab, is a function of the transverse wave number. Using this expression for the characteristic surface impedance, the electric field excited by an electric line source parallel to the slab is derived. This solution is shown to be in good agreement with one derived from a rigorous analytical solution of the wave equation for the near, intermediate, and far‐field regions.
Theoretical properties of two‐dimensional electrojet turbulence
Authors: Rognlien Thomas D. , Weinstock Jerome
Published: February 2008

Turbulence in the equatorial electrojet is attributed to the nonlinear evolution of the gradient drift instability. Solutions are given for a set of nonlinear coupled differential equations for the amplitudes of a two‐dimensional Fourier series representing the density fluctuations. The differential equations are derived from the electron and ion fluid equations by retaining the divergence of electron flux as the only nonlinearity. The results pertain to daytime conditions when dissociative recombination is the dominant linear wave damping mechanism. The irregularities reach amplitudes of ∼ 10% and are found to break up into smaller dominant scale sizes in the horizontal westward direction than in the vertical direction. A steepening of the density waveform appears in the vertical direction. Perturbed electron velocities form vortex patterns and reach magnitudes comparable to the mean electrojet drift speed.
On airborne wave tilt measurements
Authors: King R. J.
Published: February 2008

The relationship between the wave tilt and the local surface impedance for ground waves propagating over a nonhomogeneous surface has been studied. It is shown that a sufficient condition for their equivalence is that the normal (vertical) electric field and the tangential (horizontal) magnetic field be simply related by the intrinsic impedance of free space. The “phase quadrature” airborne method of measuring the imaginary part of the wave tilt is modified to allow measurement of the imaginary part of the surface impedance. A second method for airborne measurement of the wave tilt is also proposed. It uses two orthogonal electric dipoles lying in the plane of incidence, oriented so that errors resulting from small mechanical misalignment are second order. Both the magnitude and imaginary part of the wave tilt can be measured. The system is best suited for airborne reconnaissance mapping of poorly conducting areas, giving basic information concerning the electrical properties and structure of the uppermost few meters of ground. The basic instrumentation is described but the tasks of development and testing remain.
Directional dispersion of sporadic‐E modes between 9 and 14 MHz
Authors: Sherrill W. M. , Smith G. A.
Published: February 2008

Visibility function analysis of sporadic‐E mode fine structure was performed on a 830 km path between 10 and 14 MHz. Angular spectra derived show resolved doublet magnetoionic components with angular separation of 4.5 to 6 deg. Individual singlet components appear with 1 to 2 deg angular width. Compared to other mode fine structure data, these results indicate increased azimuth spread and multiple lines predominate on paths less than 1000 km, while longer paths more nearly conform to 1 to 2 deg core and halo distributions.
Evaluation of an implantable electric‐field probe within finite simulated tissues
Authors: Bassen H. , Herchenroeder P. , Cheung A. , Neuder S.
Published: February 2008

A set of miniature isotropic probes has been used experimentally to map electric fields within two small spheres of simulated muscle tissue (3.3‐cm and 8‐cm radii) that were irradiated by 450‐, 915‐, and 2450‐MHz plane waves. Good agreement was obtained with the theoretically predicted spatial distribution of fields in both spheres, even in the immediate proximity of the boundaries. The absolute calibrations of the probes were found to be moderately to significantly dependent upon the dielectric constant of the medium (1 ≤ ∈r ≤ 50) in which the probe was implanted, with the least dependence occurring at 2450 MHz (±2.25 dB), and the greatest dependence occurring at 450 MHz (±4.25 dB). A set of design criteria is presented that are necessary for proper performance of such a dipole/diode probe. Of particular importance are the thickness of the insulation surrounding the dipole antenna, and the dimensions of the dipole. Both must be small compared to the wavelength of the field in the biological media. The validity of the design criteria has been experimentally demonstrated, illustrating the feasibility of producing an improved probe whose response to an electric field of given strength would be relatively constant regardless of the dielectric constant of the media and independent of boundary‐proximity effects. Preliminary results of in vivo measurements are presented; improved, biologically compatible designs are discussed.
Radiators for microwave biological effects research—waveguide slot array with constant radiation intensity
Authors: Hagmann Mark J. , Gandhi Om P.
Published: February 2008

A longitudinal‐shunt slot array with reflectors has been designed, built, and tested. The antenna is easily matched near the design frequency. The radiation pattern has an intensity within ±0.5 dB over a total angle of 15.6° in the H plane and 15.5° in the E plane. Gain is 19.7 dB which is 3.9 dB above that of a horn with a similar work area. By using energy‐absorbing material, it is possible to produce a pattern in which the fields drop suddenly from the nearly constant values to nearly zero.
Effects of radio‐frequency radiation on inflammation
Authors: Liburdy Robert P.
Published: February 2008

Inflammatory responses, which were induced in rats by a subcutaneous injection of sheep red blood cells (SRBC) into footpads, and in mice, by tail‐vein trauma due to sequential bleeding, were observed in animals that had been pretreated wth 26‐MHz radio‐frequency radiation (RFR) or with a frank thermal burden. Pretreatment of rats by RFR decreased the severity of SRBC‐induced inflammation; averaged thickness of the footpad was less by 33.0% and 45.6%, respectively, than thicknesses observed in thermally treated and control animals. White blood cell (WBC) counts in RFR pretreated, tail‐vein traumatized mice remained constant, in contrast to the leukocytosis that was observed in air‐heated and in sham‐exposed animals. Moreover, the inflammatory response in RFR‐treated mice was accompanied by a well‐defined but transient refractory state in the number of circulating specialized leukocytes. The 92‐hour time course of the refractory state was characterized by a transient fourfold decrease of lymphocytes and a fourfold increase of neutrophils that peaked three hours after exposure; these changes were in marked contrast to those observed in thermal and passive controls. The results indicate that RFR can attenuate an inflammatory reaction. This inhibitory property may have relevance to immunocompetency of cell‐mediated immunity (CMI), since CMI responses invoke nonspecific inflammatory reactions.
A teratological study of the rat: Microwave and infrared radiations compared
Authors: Chernovetz M. E. , Justesen D. R. , Oke A. F.
Published: February 2008

Primigravid rats were exposed for 20 min to microwave radiation (2450 MHz;
) in a multimode cavity or to infrared radiation in an incubator (
∼ 47 °C). They were exposed during one of seven days of gestation, the 10th through 16th. The Δ
of the dams' colonic temperature, about 3.5 °C, was equated in the microwave and infrared treatments. Control groups of primigravid dams were sham radiated. During the 19th day of gestation, fetuses were taken by Caesarian section and were examined for structural abnormalities and for insult. In addition, fetal brains were analyzed for levels of dopamine (DA) and norepinephrine (NE). Findings: (1) the incidence of lethal dosing was 27% and 12%, respectively, in microwave‐ and infrared‐irradiated dams; (2) the averaged numbers of fetal resorptions in infrared‐ and sham‐irradiated dams are low (both ∼2%) but the number is elevated nearly sixfold in microwave irradiated dams; (3) the incidence of mortality in nonresorbed fetuses was nil; (4) extensive hemorrhagic signs were observed in both microwave‐ and infrared‐irradiated fetuses but there was no discernible evidence of structural malformation; (5) averaged fetal mass is slightly (10%) but reliably smaller in both irradiated groups as compared with controls; and (6) averaged whole‐brain DA levels do not differ reliably as a function of treatment but the averaged level of NE in brains of microwave irradiated fetuses is reliably below those of infrared and sham‐radiated fetuses. While the averaged ΔTs of the two groups of irradiated dams are equal, increments of temperature of microwave irradiated dams were more variable; correlative analysis provided evidence that mortality and resorption are probably a function of peak body temperature irrespective of source of radiation.
The effect of ambient temperature on the reduction of microwave energy absorption by mice
Authors: Monahan John C. , Ho Henry S.
Published: February 2008

Previous research has established that exposure to microwave radiation above a critical level is associated with a reduction across time in the rate at which the energy is absorbed by a mouse. Microwaves caused the animal effectively to decrease the radiation by decreasing the percent absorption of the incident energy. The current investigation sought to determine the effect of ambient temperature on this behavior. Male CFI mice (30 to 34 g) were irradiated by 2450‐MHz CW microwaves for 20 minutes in an environmentally controlled waveguide at temperatures of 20, 24, 30, or 35 °C and at a relative humidity of 50±1.5 percent. Forward power in the waveguide ranged from 0.004 to 4 W, which resulted in averaged dose rates of 0.06 to 64 mW/g. When the averaged dose rates were above a critical level, the percent absorption decreased after the initial five minutes of irradiation and remained lower for the duration of the exposure. The threshold level of power at which decreases in percent absorption were observed was found to decrease with an increase in the environmental temperature. The data suggest that the subjects were capable of detecting or otherwise reacting to microwave energy at dose rates as low as 0.6 mW/g when the environmental temperature was 35 °C.
Measurement of the impedance of a linear antenna in a magnetoplasma
Authors: Sawaya K. , Ishizone T. , Mushiake Y.
Published: February 2008

Impedance of a monopole antenna oriented at various directions with respect to the static magnetic field has been measured in an RF‐generated magnetoplasma. The antenna length is comparable to a free space wavelength. To interpret the experimental results, theoretical values of the input impedance have been calculated by using the EMF method with a uniaxial approximation for the magnetoplasma and some other assumptions. The agreement between theoretical values and measured data has been fairly good except that the effective collision frequency has been much higher than that expected from the collision cross section. Some interesting resonance phenomena of the antenna impedance, depending on the antenna length and the slant angle with respect to the static magnetic field, have been observed.
Comparisons between strong HF backscatter and VHF radar aurora
Authors: Oksman J. , Möller H. G. , Greenwald R.
Published: February 2008

It is well known that various types of irregularity structures exist in the E and F regions of the auroral and subauroral ionosphere. In this study the location and occurrence probability of these structures have been compared with HF and VHF radars located in Finland and Germany. It has been found that E‐region radar aurora is observed at both HF and VHF frequencies and that its cross section approximately follows a λ3 law in this frequency range. The F‐region irregularities and the backscatter echoes caused by them are found to fall into auroral and nonauroral groups. The auroral group occurs near the L values of radar aurora and is often observed on the same magnetic field unes as the equatorward portion of the VHF radar aurora. Moreover, there is a second type of F‐region echo that appears to be anticorrelated with radar auroral activity. This latter type of F‐region echo occurs at lower latitudes (L value between 3 and 4) and appears to require low electron densities in the F region. HF and VHF radar auroras are known to be produced by electrostatic plasma streaming instabilities. The sources of F‐region HF backscatter are not as yet known; however, they may be due to either irregular structures in particle precipitation or to plasma instability mechanisms.
Activity of membrane‐bound enzymes exposed to sinusoidally modulated 2450‐MHz microwave radiation
Authors: Allis John W. , Fromme Madeline L.
Published: February 2008

Membrane‐bound enzyme systems were irradiated with sinusoidally modulated microwave radiation in a spectrophotometric apparatus in which enzyme activity was measured during irradiation. The enzymes chosen for study were cytochrome oxidase, a key enzyme in the electron‐transport chain that is located in the inner membrane of mitochondria, and adenosine triphosphatase (ATPase) from red‐blood‐cell membrane, which is involved in maintaining the sodium‐potassium balance of the cell. The enzyme systems were prepared from rat tissue and were subjected to 2450‐MHz radiation sinusoidally modulated at 16, 30, 90, and 120 Hz; the specific absorption rate was 26 mW g−1. Temperature was controlled at 25±1.0°C in all experiments. Irradiation began immediately after initiation of the reaction and continued for several minutes while the reaction rate was being monitored. Cytochrome oxidase activity was measured directly by monitoring the change in absorbance of its substrate, cytochrome c, at 550 nm. Activity of ATPase was measured by a coupled‐enzyme system in which the rate of conversion of ATP to ADP was followed at 340 nm by stoichiometric oxidation of NADPH. The enzymes pyruvate kinase and lactate dehydrogenase performed the intermediate steps and were always present in excess so that the activity of ATPase was rate controlling. No statistically significant differences in enzyme activities were obtained between irradiated and control samples at any of the modulation frequencies for either enzyme system.
Quantitation of effects of repeated microwave radiation on muscle‐cell osmotic state and membrane permselectivity
Authors: Portela Adolfo , Guardado María Inés , de Xammar Oro Juan R. , Brennan Margarita , Trainotti Valentin , Stewart Peter A. , Pérez Roberto J. , Rodríguez Carlos , Gimeno Alvaro , Rozzell Thomas C.
Published: February 2008

Frogs (Rana pipiens) were exposed daily for six minutes to pulsed, 2.88‐GHz microwave radiation at an average power density of 10 mW cm−2 under controlled conditions in a calibrated anechoic chamber for periods of 20 to 100 days. Single‐fiber preparations of Tibialis anticus muscle were analyzed for osmotic responses, and the following quantities were determined: osmotically effective cell‐water fraction, Weff; cell‐membrane water permeability, Pw; Staverman's reflection coefficient (σ) for mannitol, sucrose, glycerol, urea, acetamide, ethylene glycol, and formamide; and equivalent pore radius of the membrane. No changes were detected in any of these endpoints as a consequence of repeated exposure to the radiation. Mean values found were: Weff = 0.50; Pw = 0.40 cm4 Osm−1 s−1; equivalent pore radius = 4 Å.
Intensity of microwave irradiation and the teratogenic response of Tenebrio molitor
Authors: Green Donald R. , Rosenbaum Fred J. , Pickard William F.
Published: February 2008

Pupae of Tenebrio molitor were individually irradiated for two hours by CW 9.0‐GHz microwaves in X‐band waveguide (TE‐10 mode) at fixed power levels of incident radiation; the power levels ranged from 10 to 320 mW and resulted in estimated dose rates approximating 25 to 800 mW g−1. Subsequent examination of adults for gross structural abnormalities revealed that the occurrence of defects was a complex function of power level of incident radiation: as the level was increased from 10 to 80 mW, incidence of defects first increased and then decreased; above 80 mW, the incidence of defects increased once more. The probability of pupal mortality increased only in the region above 80 mW. Neither intact (“ideal”) nor structurally defective (“nonideal”) pupae exhibited much evidence of teratogenesis at 80 mW; other‐wise, as observed earlier in our laboratory, ideal pupae were more resistant to insult at levels of irradiation in the range 20 to 320 mW. Data are also presented which indicate that susceptibility to microwave irradiation might be positively correlated with culturing and exposure of Tenebrio under conditions of low relative humidity.
Middle and upper atmosphere radar (MUR) under design in Japan
Authors: Fukao S. , Kato S. , Aso T. , Sasada M. , Makihira T.
Published: February 2008

A large MST radar for observing backscattering from refractive index fluctuations in the middle and upper atmosphere is now under design in Japan. The proposed system is a pulse‐modulated monostatic radar, working at a frequency near 48 MHz. The configuration will be quite different from the existing MST/ST radars. A quasi‐square array with an aperture of 104 m2 is composed of 456 Yagi antennas, each of which is provided with a low‐power amplifier. A peak output power of more than 1 MW is envisaged to be generated when the whole system is coherently activated. In this system a phase shift is obtainable at a low power level by variable phase shifters controlled by electronic means, which enable rapid and continuous scanning of the antenna. The whole system is monitored and controlled by a microcomputer network.