bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross‐equatorial air mass exchanges
Authors: Holl Manfred M. , Wolff Paul M. , Bush Yeager A. 
Published: February 2008

A method is described to compute atmospheric mass time series from a data base of sea‐level pressure analyses. The short‐term hemispheric mass exchange is used to examine the validity of this method.A 1/6 degree by 1/6 degree, latitude and longitude, terrain data base, provided by the Fleet Numerical Oceanography Center (FNOC), is used to reduce sea‐level pressure to surface pressure. Surface pressure is converted to mass and summed. The FNOC sea‐level pressure and the European Center for Medium Range Weather Forecasting (ECMWF) 1000‐mb analyses are used to compute the mass and generate time series for the Northern Hemisphere 1946–1987 and the Southern Hemisphere 1981–1987.The Northern Hemisphere and Southern Hemisphere mass time series are combined to show that exchanges of atmospheric mass occur between hemispheres on the order of several millibars (equivalent mass) on a time scale of days to weeks. The larger exchanges typically occur during the Northern Hemisphere winter.
Implications of the stability and radiative time constant of Triton's atmosphere
Authors: Stern S. Alan 
Published: February 2008

This paper examines both Triton's atmospheric escape rates and radiative timescales.We first calculate the range of plausible atmospheric escape rates and examine the implications of these escape fluxes. If even modest hydrodynamic escape is occurring, escape rates can exceed the ion pickup rates predicted by Delitsky, et al. (1989). This process is expected to develop a torus of gas in orbit around Neptune. If Triton's escape flux exceeds ∼ 1010 cm−2 sec−1, a substantial amount of ancient icy surface topography may have been lost to escape.We also calculate the radiative timescale in Triton's atmosphere as a function of surface temperature, atmospheric pressure, and composition. It is shown that if N2 obtains saturation vapor pressure equilibrium, then diurnal variations will be negligible. If N2 is far from saturation or if only CH4 is present, then both diurnal and seasonal effects may be expected. Recent observations indicate the presence of decadal‐timescale atmospheric variations. Radiative timescale constraints imply that if these observations are correct, then the present atmospheric pressure is unlikely to much exceed ≈100 mb.
Increased cloudiness in the United States during the first half of the Twentieth Century: Fact or fiction?
Authors: Karl Thomas R. , Steurer Peter M. 
Published: February 2008

A new source of cloud and sunshine data, in conjunction with an inspection of the observing practices, instruments, and daily temperature range over the United States, are used to confirm or contradict the large increases of cloudiness previously reported. This analysis indicates that changes in observing practices are primarily responsible for the reported increase of cloudiness during the first half of the this Century. The response of the sunshine instruments and the surface daily temperature range over the United States are not consistent with the reported increases during the first half of this Century. Since the late 1940s however, the increase of cloud cover is confirmed by an inspection of the sunshine data, daily temperature range, changes in instruments, and the instructions to the observers. The types of changes in the cloud observing practices during the late 1930s and 1940s would tend to lead to increases in reported cloud amounts. Although we have not yet produced a combined sunshine/cloudiness index of cloud cover over the Twentieth Century, some cogent inferences can be made at this time:

Monotonic trends of cloudiness on the Century time‐scale do not exist in the United States.
Fewer clouds were present during the 1930s and early 1950s.
There has been a tendency toward increased since 1948.
The effect of stress cycling and inelastic volumetric strain on remanent magnetization
Authors: Martin R. J. , Habermann R. E. , Wyss M. 
Published: February 2008

The relation between remanent magnetization (natural and thermal), volumetric strain, and stress was determined for five rock types. Twenty different samples (fine‐grained intrusive, gabbro, basalt, tuff, and andesite) were repeatedly cycled to 95% of their fracture stresses at confining pressures of up to 1250 bars. At the completion of the first cycle there was always a permanent demagnetization of the rock. Subsequent stress cycles show a progressively smaller demagnetization, and the changes of remanence with loading become nearly reproducible by the fourth cycle. The onset of dilatancy produced changes in the rate of magnetization change. For two rock types the magnitude of the remanence increased up to the onset of dilatancy and then decreased as the stress was augmented. For these two rock types the remanent vector first rotated toward the axis of applied stress up to the onset of dilatancy; continued loading caused a rotation away from the applied stress axis. Typically, the changes in remanent intensity were of the order of 5%, which is about 3 times smaller than the changes in the individual components parallel and perpendicular to the axis of the greatest compressive stress. In fact, it was not uncommon for one component to increase while the other decreased. As a consequence, large rotations, up to 10°, of the remanent moment were observed, and at differential stresses in excess of half the compressive strength the remanent vector always rotated away from the axis of greatest compression. In addition, time dependent changes in remanent magnetization of several percent accompanied time dependent increases in crack porosity during constant stress creep tests at high differential stresses.Table 2 is available with entire article on microfiche. Order from American Geophysical Union, 1909 K Street, N.W., Washington, D.C. 2006. Document J78‐003; $1.00. Payment must accompany order.
Zonal and geographical distributions of cirrus clouds determined from SAGE data
Authors: Woodbury Gerard E. , McCormick M. P. 
Published: February 2008

An analysis using Stratospheric Aerosol and Gas Experiment (SAGE) data for the period February 1979 to November 1981 was performed to determine the spatial extent and frequency of occurrence of cirrus clouds over a large portion of the earth's surface. The effective field of view corresponding to the determined frequency was 100 km2. A by‐product of the study reveals the statistics of tropospheric observational opportunities for a limb‐sounding satellite sensor by determining the percentage of times of successful penetration to a given height or depth below the tropopause.The results of the analysis showed that optically thick cirrus clouds form most often in the midlatitudes and over the tropics, with distinct minima near latitude bands of 20°–30° north and south. The zonally averaged latitudinal distributions of cirrus clouds observed by SAGE compared very well with the Nimbus 5 selective chopper radiometer (SCR) observations in shape but not in magnitude. SAGE showed about twice the magnitude of the SCR results. The percentage of tropospheric observational opportunities down to 7 km was as high as 60% in the upper latitudes. A geographical presentation of the SAGE results showed the growth and seasonal movement of high‐cloud features were in good agreement with previous studies.
A model for planetary igneous differentiation
Authors: McConnell Robert K. , McClaine Leslie A. , Lee D. William , Aronson James R. , Allen Ronald V. 
Published: February 2008

Numerical models for igneous activity on any planet must be based on thermal properties and melting relationships for realistic multicomponent systems. A consistent model for the composition of the earth's mantle may be obtained by considering a mixture of basalt and dunite, as postulated by Ringwood and others, if the uranium, thorium, and potassium concentrations of the basalt are similar to that of basalts dredged from the deep ocean floors. Present evidence does not indicate that the bulk composition of the moon is appreciably different from that of the earth's mantle.On the basis of a review of existing phase equilibria and high pressure studies, we predict melting behavior as a function of pressure and temperature for a composition equivalent to 1 part basalt and 3 parts dunite. The specific heat and fusion properties of the important minerals in this system are reviewed. The implications of these data for an understanding of magma generation are discussed.A review of the factors influencing the thermal conductivity of rocks indicates that when considering the details of heat conduction under conditions likely to be encountered within the earth's upper mantle and the moon, a model invoking constant phonon conductivity and temperature independent photon mean free path may be unrealistic. A more likely, but still oversimplified, model has a phonon conductivity inversely proportional to temperature, and, unless scattering dominates, a photon mean free path directly proportional to temperature over the range of interest. Pressure should not significantly affect the thermal conductivity within the upper mantle, except by changing the stable mineral assemblage.When the more important aspects of the melting relationships and thermal properties of the model composition are selected and used to extend thermal history calculations of the moon to include the effects of differentiation through igneous activity, the calculations indicate that a brief period of intense volcanic activity is likely to have occurred at a time which is primarily a function of the moon's temperature at the time of its formation and the concentration of radioactive heat sources. If the temperature of the moon at the time of its formation were 0°C and the uranium content were 0.05 ppm, with Th/U and K/U in the ratio 3.7 and 104, respectively, melting would have begun about 1.5 × 109 years after formation, the intensity being largely controlled by the thermal conductivity. At lower U, Th, and K contents, the onset of volcanism would have been delayed or suppressed completely, depending on the conductivity. Properly selected samples of the moon's surface rocks should thus make it possible to determine its initial temperature. The total thickness of extrusive and intrusive igneous rocks is shown to be critically dependent on the efficiency of radiative heat transfer in removing heat from the interior.
Oceanic fine and microstructure
Authors: Gregg M. C. 
Published: February 2008

During the past quadrennium there has been a large increase in the effort directed toward the smallest scales of variability in the ocean. The importance of this undertaking in relation to the basic physics of the sea was discussed in the previous quadrennial report by C. S. Cox and in general discussions by Charnock [1972] and Gregg [1973]. The work has included instrumentation, the development of complete data acquisition systems as well as individual sensors; observation, the display of high‐quality data to millimeter scales as well as more quantitative information on spectral levels and dissipation rates; analytical models, principally the development of a framework for discussing and comparing observations of temporal and spatial variability; and laboratory experiments, which have shown continued insights into double diffusivity phenomena and shear instabilities.In discussing particular developments in each of these categories there must be mention of work done on internal waves; however, for a complete discussion of this area the reader is referred to the companion review in this series by M. G. Briscoe.
Numerical weather prediction
Authors: Leith C. E. 
Published: February 2008

Various numerical models are in use for prediction of the large‐scale motions of the atmosphere for operational or research purposes, and all seem to have comparable skill for several days, as shown by Druyan [1974] in a comparison of the Goddard Institute for Space Studies (GISS) [Somerville et al., 1974] model forecasts with those at the National Meteorological Center (NMC) [Shuman and Hovermale, 1968], the Fleet Numerical Weather Central (FNWC) [Kesel and Winninghoff, 1972], and the Geophysical Fluid Dynamics Laboratory (GFDL) [Miyakoda et al., 1972]. There have also been many models developed for treating limited areas with higher resolution, as described in a paper by Chen and Miyakoda [1974], in which many references to such models may be found.The principal topics of this review, however, will be the recent research on the question of the theoretical predictability of the large‐scale motions of the atmosphere, on the design of a global observing and data assimilation system, and on the development of statistical‐dynamical forecasting models. These all relate to the first objective of the Global Atmospheric Research Program (Garp), namely, increasing the accuracy of forecasting over periods of 1 day to several weeks.
Positioning by satellites
Authors: Brown Duane C. 
Published: February 2008

During the previous reporting period (1971–1974) accuracies of geodetic positioning by satellites had been pushed from the level of 5 meters rms or so characteristic of the NGS Worldwide Geodetic Satellite Triangulation to the level of 1 meter rms characteristic of routine satellite Doppler positioning based on use of precise ephemerides. To be sure, within this period the threshold of 1 meter was being broached by various NASA laser ranging experiments and by various experiments with Very Long Baseline Inferferometry (VLBI). These, however, were in the category of special exploratory endeavors involving only a relatively few stations occupied for extended periods and could hardly be regarded as routine.During the current reporting period (1975–1978) accuracies have been pushed in several disciplines toward the 10 cm level, and the stage is being set for advancement toward the 1 cm level. This has been a period of extraordinary progress with particular impetus being provided by the challenge of precise monitoring of crustal movements over extensive regions of high seismic activity. More mundane, but of greater immediate impact has been the spectacular increase in the application of satellite Doppler positioning throughout the world. From the standpoint of economic significance this certainly qualifies as the most important single development in positioning by satellites during the current period. Accordingly, Doppler technology is accorded special prominence in this review. This is not to slight the impressive advances made in laser tracking and VLBI technology. However, these topics are addressed at some length in other sections of this issue and thus need not be pursued as deeply here. A similar remark applies to the Global Positioning System which is still in an early developmental stage and can therefore presently be addressed more from the standpoint of theoretical potential than from practical experience.
Cloud physics: A review for 1975–1978 IUGG Quadrennial Report
Authors: Cotton William R. 
Published: February 2008

Major advances in cloud physics for the period 1975 to 1978 are reviewed. The topics include the physics of nucleation, precipitation physics, electrical charging processes, dynamics of convective clouds, physics and dynamics of layer clouds, and clouds in extratropical cyclones.2.0 Warm‐cloud Nucleation and Cloud Condensation NucleiThe experiments of Katz and Kocmond (1973) cast considerable doubt upon the ability of heterogeneous nucleation (condensation) theory as described by Fletcher (1962) to predict the relationship between the size and critical supersaturation of aerosols. The former concluded that salt particles, nucleating water at a given supersaturation, produced droplets whose radii were two to three times larger than the radii predicted by theory. More recent experiments, however, by Twomey (1977), using atmospheric aerosol, and Gerber, et al. (1977), using both NaCl and (NH4)2 SO4 aerosol, provide rather convincing evidence that the relationship between size and critical supersaturation predicted by theory is consistent with their experimental results.
Control surveys
Authors: Gergen John G. , Whalen Charles T. 
Published: February 2008

North American Datum (NAD) Readjustment Project. The NAD readjustment project of the National Geodetic Survey (NGS) consists of three major tasks: the validation of all field projects, the validation of individual blocks, and the solution of the equations associated with each observation. Associated tasks include: researching mathematical models, defining detailed procedures, and developing required software. The validation of 4,890 field projects involved the keying of 2.5 million direction observations, the reprocessing of 60,000 electronic distance measurements, and the separate least‐squares adjustment of each field project.Block validation consists of the systematic analysis of observational data within more than 800 blocks. This task began in July 1982, and is expected to continue for 2 years. The partitioning of the U.S. horizontal network into blocks, and the systematic reduction of the equations by the Helmert blocking method, represents the last task of the project. Block validation testing began in the fall of 1982.
Crustal geologic studies with Magsat and surface magnetic data
Authors: Mayhew Michael A. , LaBrecque John L. 
Published: February 2008

In this review we discuss the contributions during the last quadrennium which involved both Magsat and aeromagnetic data, including new techniques for interpreting this data, specific regional investigations, and laboratory studies intended to understand the connection between magnetic anomalies and the magnetic mineralogy of their sources.In recent years it has become commonplace to present the data obtained from magnetic surveys in the form of digital images. Techniques for applying special filters appropriate for potential fields and the image enhancement tricks developed by the remote sensing community have come in to widespread use, and were very much in vogue among U.S. investigators during this quadrennium. A key paper by Cordell and Grauch (1985) described a procedure for extracting full information from an aeromagnetic survey for the purpose of mapping basement units under variable‐thickness sedimentary cover; it combines a Taylor series approximation with standard FFT computations (Hildenbrand, 1983). A topographically draped survey is continued to a level surface just above the highest topography using the Taylor series technique, downward continued to the mean basement level via FFT and applying a low‐pass filter, then draped over the basement surface. Aliasing problems exist, but are minor. Magnetization boundaries are then delineated by the horizontal gradient of the pseudogravity distribution. Using sparse well data for constraint, it was possible to make a basement magnetization map for the San Juan Basin, New Mexico, in a detail which would not have been possible with the original data as flown. Blakely and Simpson (1986) developed an automated procedure for delineating magnetization (or density) boundaries for machine application of the Cordell‐Grauch method; this is simply an efficient way of finding the loci of maxima in the horizontal gradient for a grid of data.
Advances in the chemistry of rivers, estuaries, microcosms, and salt marshes—1983–1986
Authors: Church Thomas M. 
Published: February 2008

There have been dramatic advances in our knowledge of chemical processes in coastal waters during the past several years. Much of this work in the U.S. has focused on estuaries using larger seasonal data sets, advanced analytical techniques, and process oriented studies. The processes of interest include the scavenging of riverine substances in estuaries, the recycling of nutrient components, diagenetic exchange with anoxic sediments, and tidal flushing of land derived material and pollutants to the sea. As estuarine systems interact with the geo‐ and biosphere in a complex way, empirical data sets have been supplemented by experimental approaches including mixing experiments and controlled microcosms. Since most river‐estuarine systems experience tidal flushing, fringing intertidal salt marshes/mangroves appear to be important buffers for chemical storage, recycling, and exchange.Principle rivers of the world provide an important means for the transport of terrestrial constituents to the ocean. However, estuaries constitute an important transition zone which can provide a buffer for the extraction and recycling of those elements which eventually reach the sea. There have been important advances over the past several years by U.S. investigators showing how inorganic and organic constituents of rivers are involved either in direct (riverine) or indirect (estuarine) transport to coastal waters. These more recent studies provide both a quantitative basis and process orientation for delineating estuarine transport. This report will summarize progress in the United States since 1982 in studies of rivers, estuaries, microcosms and salt marshes.
Height‐gain experimental data for groundwave propagation: 1, Homogeneous paths
Authors: King R. J. , Cho S. H. , Jaggard D. L. , Sokolov V. 
Published: February 2008

Experimental height‐gain data for the magnitude of electromagnetic groundwaves propagating over flat homogeneous paths were obtained by microwave (4.765 GHz) modeling. The experimental results were compared with height‐gain theory, and the limitations of the theory were established in terms of surface impedance, height of the receiving point, and antenna separation distance. Earlier experimental studies of this problem have not been entirely conclusive due to an inadequate knowledge of the surface impedance and the influence of the surface upon the antenna impedance. Here, extensive corrective measures were taken to eliminate or account for these effects.It is concluded that the theory for the total field is remarkably accurate as the height above or distance along the surface is varied, even at distances as close as 2λ0 from the source. Furthermore, the question as to the choice between the various forms of numerical distance seems academic. The restriction on height above the surface is eliminated, and the restriction upon the magnitude of the surface impedance is relaxed depending upon the presence of a significant trapped surface wave.Part 2 is a companion paper which relates the homogeneous path height‐gain to mixed‐path experimental measurements versus height and distance.
The photoelectron‐spectrometer experiment on Atmosphere Explorer
Authors: Doering J. P. , Bostrom C. O. , Armstrong J. C. 
Published: February 2008

The Atmosphere Explorer (AE) photoelectron spectrometer experiment consists of electrostatic deflection‐type electron spectrometers designed to measure the low‐energy electron flux expected to be encountered along the AE orbit. The system has been designed to provide general information on the intensity, angular distribution, energy spectrum, and net flows along field lines as well as sufficient energy resolution to allow the fine details of the electron‐energy spectrum to be studied. The instrumentation consists of two separate electron‐spectrometer detector heads connected to a common electronics system for data processing and telemetry interfacing.The experiment will measure the electron‐energy spectrum from 2 to 500 ev (and possibly to less than 0.1 ev), The energy resolution (ΔE/E) of the electron spectrometers will be approximately 2.5% full width half maximum. The geometrical factor of the analyzers will be approximately 10−3 cm2 ster, independent of electron energy. Placement on the spacecraft will be arranged so as to give as little interference as possible from shadowing of electron trajectories by the spacecraft and contamination of the observed spectra by locally generated photoelectrons.