• Earth Current Activity at College, Alaska, July 1959

      Hessler, V. P. (Geophysical Institute at the University of Alaska, 1960-06-15)
      This report presents College N-S earth current records for the month of July 1959. The scale of 1 inch per hour permits detailed scaling directly from the reproductions in the report. Scalings of hourly range in amplitude and rapid fluctuation activity are given. The amplitude scalings are also presented as curves together with average curves for a period of several years to show the relative magnitudes of the July 1959 activity. The earth current always displays much more pronounced fine structure than the corresponding geomagnetic activity.
    • Earth Potential Electrodes in Permafrost and Tundra

      Hessler, V. P.; Franzke, A. R. (Geophysical Institute at the University of Alaska, 1957-11)
    • Equilibrium and Transport in a Fully Ionized Gas

      Brittin, Wesley Emil (Geophysical Institute at the University of Alaska, 1957-04)
    • An evaluation of auroral all-sky camera observations

      Davis, T. N.; Deehr, C. S.; Leinbach, H. (Geophysical Institute of the University of Alaska, 1960-03)
      From photometric, all-sky camera, and visual observations of a moderate auroral display, it is found that the all-sky camera compares favorably with the visual observer in detecting and recording auroral forms. The visual observer can make instantaneous observations and so can detect rapid changes and auroral forms lasting only a few seconds, whereas the poorer time resolution of the all-sky camera prevents it from recording very short-lived phenonema. However, the ability of the all-sky camera to accurately record the shape and intensity of the majority of auroral forms allows it to yield more precise and complete information about these aspects of auroral morphology than is normally obtained through visual observation.
    • Evaluation of chemical methods for the determination of atmospheric ozone

      Mukherjee, Nalin R. (Geophysical Institute at the University of Alaska, 1952-11-15)
      Since the concentration of the ozone in the atmosphere near the earth's surface is of the order of 10 gm. per gm. of air, the quantitative determination of this ozone by chemical methods is rather difficult. Therefore, the different methods have been evaluated to determine the best, all conceivable precautions being taken into account. The chemical methods may be classified into two groups --Titer Methods and Spectro-chemical Methods. Among the former, two; namely, the Thiosulphate and Arsenite Methods, have been proposed and used. For the low concentration of ozone in the atmosphere near the earth 's surface, the Thiosulphate Method is found to give unreliable results due to the instability of the thiosulphate solution as well as to various side reactions which could not be controlled. The arsenite solution, however, is much more stable than the thiosulphate solution. Side reactions are very few and can largely be controlled. Reliable results can be obtained by the Arsenite Method when employing proper precautions. The oxidants and other interfering substances in the atmosphere present serious problems. Some oxidants behave like ozone as far as the reactions with the chemical reagents are concerned. Their occurrence in the atmosphere and their effects on the chemical reagents used for the quantitative determination of the atmospheric ozone are discussed in detail. Suggestions are made for their elimination from the atmosphere without affecting the ozone concentration.
    • Experiment Luxembourg

      Rumi, G. C.; Little, C. G. (Geophysical Institute at the University of Alaska, 1958-12)
      The earlier orbits and ephemerides for the Soviet satellites were not sufficiently accurate to be very useful in making observations in Alaska. Extrapolations from our own observations gave better predictions. This merely pointed out the fact that rough observations of meridian transits at high latitudes will give better values of the inclination of the orbit than precision observations at low latitudes. Hence, it was decided to observe visually the meridian transits estimating the altitude by noting the position with respect to the stars or using crude alidade measurements. The times of the earlier observations were observed on a watch or clock and the clock correction obtained from WWV. Later the times were determined with the aid of stop watches, taking time intervals from WWV signals. This rather meager program of optical observations of the Soviet satellites was undertaken to give supplementary data for use of the radio observations, and particularly to assist in the prediction of position of the satellite so that the 61-foot radar of Stanford Research Institute could be set accurately enough to observe it (the beam width at the half-power points is about 3°). This report contains primarily the visual observations made at the Geophysical Institute by various members of the staff, and a series of observations by Olaf Halverson at Nome, Alaska. In addition there is a short discussion of the geometry of the trajectory, the illumination of a circumpolar satellite, and a note on the evaluation of Brouwer's moment factors.
    • Experiment Luxembourg, Scientific Report No. 2

      Rumi, G. C. (Geophysical Institute at the University of Alaska, 1959-05)
    • Experiment Luxembourg, Scientific Report No. 3

      Rumi, G. C. (Geophysical Institute at the University of Alaska, 1960-02)
    • Experiment Luxembourg, Scientific Report No. 4

      Rumi, G. C.; Benson, R. F. (Geophysical Institute at the University of Alaska, 1960-12)
      Experiment Luxembourg was designed to measure the electron density and electron collision-frequency as a function of height in the D region over College, Alaska using the technique of radio-wave interaction. A block diagram, which includes all the equipment necessary for the actual operation of the experiment, is described and illustrated in detail. The major parts of the system are: the disturbing transmitter operating on 17.5 Mc/s and using a 4x4 array of Yagi antennas, the wanted transmitter operating on ~ 5 Mc/s and using a circular polarization unit with 4 dipoles arranged in a quadrangle, a similar circular polarization unit and antenna for 5 Mc/s at the receiving site, and the delicate receiving system which detects a cross-modulation of 1x10 -4 for a one volt input signal. Some values of electron density and collision-frequency have been obtained and will be discussed in following publications.
    • The Height of F-Layer Irregularities in the Arctic Ionosphere

      Bates, Howard F. (Geophysical Institute at the University of Alaska, 1959-03)
      Results and interpretations of oblique incidence soundings of the arctic ionosphere are presented. Anomalous echoes are found to be prevalent in high latitudes in contrast to lower latitudes where 2F groundscatter predominates. One of the echoes seen regularly at College, Alaska has been identified as direct F-layer (IF) backscatter. The observations of the IF echo provide direct evidence of the presence of irregularities in the F-layer between heights of 350 and 600 km. The IF echoes are recorded regularly at night and occasionally during the day in disturbed periods. They appear to be associated with auroral ionization. Simultaneous reception of 2F echoes from the north and the south indicates that at times the reflecting layer is tilted. Tilt-angles in the vicinity of 2 to 3 degrees are found. The 2F echoes from the north usually connect to the extraordinary branch of the vertical incidence trace while the 2F echoes from the south appear to connect to the ordinary branch. The analysis of groundscattered (2F) echoes is extended from a plane to a spherical geometry, and it is shown that a geometrical extension of the plane earth theory is adequate. The observed range-frequency dependence differs only slightly from that predicted by the latter theory.
    • An HF sweep frequency study of the arctic ionosphere

      Bates, Howard F. (Geophysical Institute at the University of Alaska, 1961-04)
      Observations made during 1958 and 1959 using a sweep frequency, HF, oblique sounder located at College, Alaska, are discussed, and selected groups of echoes are illustrated. Groundscatter is the predominant echo type observed on mid-latitude backscatter records, but this is not true in the high latitudes. The majority of the scatter echoes from soundings toward geomagnetic north were direct F region scatter of two main types - IF and constant range echoes. These same echo types were observed from the E region during magnetic disturbances (the slant Es echo corresponds to the IF echo). These echoes were centered about geomagnetic north on swept azimuth soundings and were produced by scatter near the oblique reflection point in the ionosphere. Thus, we conclude that the echoes were caused by scatter from irregularities aligned along the geomagnetic field. The IF echo branches off the first order vertical incidence F region trace and increases linearly in range with frequency. It is produced by scattered energy which is least-time focused. The scatterers are essentially randomly distributed within large regions called clouds in the F region. The height of the irregularities producing the IF echo can be computed if the vertical incidence traces are clear; heights between 200 and 350 km have been found by this technique, indicating that electron density irregularities are not confined only to the lower ionosphere. From the regularity of occurrence of the IF echo, it is highly probable that the irregularities extend throughout much of the F region. The constant range echo is produced by energy scattered from the field-aligned surface of a cloud of irregularities. The soundings were made to the north so the clouds producing the observed constant range echo extended east and west. The IF and the constant range echoes are useful research tools because they indicate the amount of cloudiness present in the F region. During the summer day, the F region is relatively free of clouds, while during the winter night, it is quite overcast. The cloud size and distribution depend primarily upon the zenith angle of the sun, the smaller the zenith angle, the smaller and fewer the clouds. Geomagnetic effects do not appear to influence the behavior or the F region clouds, although this point is somewhat uncertain. The E region clouds which produced the slant Es echo were definitely correlated with geomagnetic activity but not to solar radiation, there appeared to be no connection between the causes of the E and the F region direct scatter echoes even though they were propagated by the same general mechanisms. This study raised several new problems whose explanations might contribute greatly to ionospheric research. The sweep frequency sounding technique is a good method, but the system sensitivity must be raised greatly over that of the present equipment if meaningful results are to be obtained.
    • Historical references to ice conditions along the Beaufort Sea coast of Alaska

      Shapiro, Lewis H.; Metzner, Ronald C.; Toovak, Kenneth (Geophysical Institute, University of Alaska, Fairbanks, 1979-09)
      The objective of this program was to extend the data base on ice hazards along the Beaufort Sea coast of Alaska backward in time by using the knowledge and understanding of ice and weather conditions of the local residents. Information for this pilot project was obtained through direct interviews with residents, or from narratives supplied by them. The results of these procedures were evaluated to provide a basis for improving similar efforts in future. Observations of particular interest obtained from these interviews and narratives include (1 ) a description of a major motion of the landfast ice off Harrison Bay in late February, (2) a description of the formation of ice push ridges and ride-up at Cape Halkett during break up, (3) reports of whales traveling inshore of Cross Island during the fall migration and of whales being taken by crews from the Prudhoe Bay area at that time of year, and 4) descriptions of conditions in the nearshore area during summer. In addition information of historical and cultural interest was obtained.
    • Ice Fog: Low Temperature Air Pollution; Defined with Fairbanks, Alaska as type locality

      Benson, Carl S. (Geophysical Institute at the University of Alaska, 1965-11)
      Stable pressure systems over interior Alaska sometimes produce prolonged, extreme (below -40°C) cold spells at the surface. The meteorological conditions responsible for two such cold spells are discussed in detail in Appendix A, where it is shown that the rate of radiative cooling of the air is enhanced by suspended ice crystals which are themselves a result of the initial cooling. Radiation fogs formed during the onset of cold spells are generally of short duration because the air soon becomes desiccated. These fogs consist of supercooled water droplets until the air temperature goes below the "spontaneous freezing point” for water droplets (about -40°C); the fog then becomes an ice crystal fog, or simply "Ice Fog". During the cooling cycle water is gradually condensed out of the air until the droplets freeze. At this point there is a sharp, discontinuous decrease in the saturation vapor pressure of the air because it must be reckoned over ice rather than over water. The polluted air over Fairbanks allows droplets to begin freezing at the relatively high temperature of -35°C. Between -35 and -40°C the amount of water vapor condensed by freezing of supercooled water droplets is 3 to 5 times greater than the amount condensed by 1°C of cooling at these temperatures. This results in rapid and widespread formation of ice fog (Appendix B) which persists in the Fairbanks area as long as the cold spell lasts. The persistence of Fairbanks ice fog depends on a continual source of moisture (4.. 1 x 10^6 Kg H2O per day) from human activities within the fog. Ice fog crystals are an order of magnitude smaller than diamond dust, or cirrus cloud crystals, which in turn are an order of magnitude smaller than common snow crystals (0.01, 0.1 and 1 to 5-mm respectively). The differences in size are shown to result from differences in cooling rates over 5 orders of magnitude. Most of the ice fog crystals have settling rates which are slower than the upward velocity of air over the city center. The upward air movement is caused by convection cells driven by the 6°C "heat island" over Fairbanks. This causes a reduced precipitation rate which permits the density of ice fog in the city center to be three times greater than that in the outlying areas. The inversions which occur during cold spells over Fairbanks begin at ground level and are among the strongest and most persistent in the world. They are three times stronger than those in the inversion layer over Los Angeles. Thus, the low-lying air over Fairbanks stagnates and becomes effectively decoupled from the atmosphere above, permitting high concentrations of all pollutants. The combustion of fuel oil, gasoline, and coal provides daily inputs of: 4.1 x 10^6 kg CO2 ; 8.6 x 10^3 kg SO2 ; and 60, 46 and 20 kg of Pb, Br and Cl respectively, into a lens-like layer of air resting on the surface with a total volume less than 3 x 10^9 m^3. The air pollution over Fairbanks during cold spells couldn't be worse, because the mechanisms for cleaning the air are virtually eliminated while all activities which pollute the air are increased.
    • Incidence of Auroras and Their North-South Motions in the Northern Auroral Zone

      Davis, T. Neil; Kimball, Donald S. (Geophysical Institute at the University of Alaska, 1960-01)
      Studies of the incidence of auroral forms and their north and south motions are made by using a close-spaced array of all-sky cameras located in the northern auroral zone at the approximate geomagnetic longitude 250°E. It is found that during the observing season 1957-58 the peak of the average auroral zone occurred at 66-67° geomagnetic latitude. Although the southern extent of auroras retreats northward after local magnetic midnight, the southward motion of the individual forms, observed at the southern edge of the auroral zone, predominates over the northward motion throughout most of the night. The data indicate the existence on any given night of a latitude position near which many auroral forms occur. The first motion of auroras incident north of this position tends to be northward, and the first motion of auroras incident south of this position tends to be southward. A curve showing the occurrence of auroral forms peaks at, and is nearly symmetrical about, local geographic midnight, but the intensity of auroral emissions measured over the celestial hemisphere remains at a high level after midnight.
    • Indices of Upper Atmospheric Disturbance Phenomena in Auroral Zone

      Elvey, C. T.; Sugiura, M. (Geophysical Institute at the University of Alaska, 1958-12)
      The earlier orbits and ephemerides for the Soviet satellites were not sufficiently accurate to be very useful in making observations in Alaska. Extrapolations from our own observations gave better predictions. This merely pointed out the fact that rough observations of meridian transits at high latitudes will give better values of the inclination of the orbit than precision observations at low latitudes. Hence, it was decided to observe visually the meridian transits estimating the altitude by noting the position with respect to the stars or using crude alidade measurements. The times of the earlier observations were observed on a watch or clock and the clock correction obtained from WWV. Later the times were determined with the aid of stop watches, taking time intervals from WWV signals. This rather meager program of optical observations of the Soviet satellites was undertaken to give supplementary data for use of the radio observations, and particularly to assist in the prediction of position of the satellite so that the 61-foot radar of Stanford Research Institute could be set accurately enough to observe it (the beam width at the half-power points is about 3°). This report contains primarily the visual observations made at the Geophysical Institute by various members of the staff, and a series of observations by Olaf Halverson at Nome, Alaska. In addition there is a short discussion of the geometry of the trajectory, the illumination of a circumpolar satellite, and a note on the evaluation of Brouwer's moment factors.
    • An Investigation of Whistlers and Chorus at High Latitudes

      Pope, J. H. (Geophysical Institute at the University of Alaska, 1959-04)
      The whistlers and chorus received at College, Alaska during the period from December 1955 through March 1958 are studied particularly with respect to temporal variations. The diurnal curves for whistler activity show maxima after midnight local time while the seasonal variation peaks during the winter. It appears that these variations in whistler activity are in part explainable in terms of very low frequency propagation conditions. The diurnal variation of chorus shows a maximum at about 1400 hours local time. By the use of data from lower latitude stations a dependence of this time of diurnal maximum on the geomagnetic latitude of the station is shown. The coefficients of correlation for chorus activity versus magnetic activity were determined on a monthly basis. A seasonal variation in these correlations is indicated which appears to be unique for the geomagnetic latitude of College. A preliminary statistical study of one of the more easily measured characteristics of chorus is discussed. The characteristic chosen is the mid-frequency in an element of chorus. A diurnal variation in this parameter is indicated.
    • Low Energy Cosmic Ray Events Associated With Solar Flares

      Reid, George C.; Leinbach, Harold (Geophysical Institute at the University of Alaska, 1959-09)
    • Luminous night clouds and low latitude auroras

      Elvey, C.T. (Geophysical Institute at the University of Alaska, 1955-09)
    • A Magneto-Ionic Theory of the Aurora

      Reid, G. C. (Geophysical Institute at the University of Alaska, 1958-12)
      A qualitative description of the development of a typical auroral display as the result of an electrical discharge in the ionosphere is presented. The prime cause of the discharge is taken as the potential difference existing between points in the interplanetary medium as a result of an interaction between charged particles of solar origin and the earth's magnetic field. The characteristics of the occasional very intense aurorae visible over large areas of the earth are discussed, as well as the normal diurnal and seasonal variation of auroral occurrence. The origin of the electric field is discussed, and a possible explanation in terms of particles trapped in the earth’s magnetic field, is presented.
    • The measurement of ionospheric absorption using extraterrestrial radio waves

      Little, C. G. (Geophysical Institute at the University of Alaska, 1957-01-28)
      Introduction: The discovery by Jansky in 1932 of the presence of radio waves incident upon the earth from outer space has led to several new methods of studying the earth's upper atmosphere. This report describes the manner in which these extraterrestrial radio waves may be used to measure the radio absorption characteristics of the ionosphere. It opens with a brief discussion of the theory of ionospheric absorption; this is followed by a description of the basic principles involved in this new technique. Two different types of equipment which may be used for this type of absorption measurement are then discussed. The report concludes with a brief summary of three types of ionospheric absorption phenomena which have been studied at various latitudes with such equipments.