Carbon dioxide clathrate in the Martian ice cap
Carbon dioxide clathrate in Martian ice cap suggested from hydrate stability relative to solid phase and water ice as function of temperature
Miller, S. L.↗
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Martian north polar cap, 1962-68
Martian north polar cap observations, discussing physical aspects and seasonal regression curves
Capen, C. F.↗
The surface of Mars. I - Cratered terrains. II - Uncratered terrains. III - Light and dark markings. IV - South polar cap
Mars surface TV pictures from Mariner 6 and 7, including cratered and uncratered terrains, light and dark markings and south polar cap
Cutts, J. A.↗
Atomic processes in the polar cap
Polar cap atomic processes stimulated by photons, electrons and protons, considering particle morphology
Green, A. E. S.↗
Asymmetric access of energetic solar protons to the earth's north and south polar caps
Energetic solar protons asymmetric access to north south polar caps by satellite observation during 24 January 1969 event
Fennell, J. F.↗
Measurement of the effective electron loss rates in the D region during polar cap absorption events
Day and nighttime effective electron loss rate measurement in D region during polar cap absorption events, using rocket-borne spectrometers and Faraday rotation
Adams, G. W.↗
Mariner ultraviolet spectrometer - Topography and polar cap
Mariner 1969 flyby Mars UV spectrum observations, interpreting data in terms of atmospheric, topographic and polar cap adsorptive characteristics
Barth, C. A.↗
Electric-field measurements and the identification of currents causing magnetic disturbances in the polar cap
Polar cap electric field and relationship to magnetic disturbances from measurements on Ba ion clouds released by rockets
Heppner, J. P.↗
Distributions of plasmas and electric fields over the auroral zones and polar caps
Low energy particle plasma sheet and convection electric field distributions over auroral zones and polar caps from satellite Injun 5 observation
Frank, L. A.↗
A digital computer study of the buckling of shallow spherical caps and truncated hemispheres
A study of the buckling of thin shells was conducted using a digital computer program for the geometrically nonlinear analysis of arbitrarily loaded shells of revolution. The objective was an evaluation of the program's applicability to bifurcation buckling and imperfection sensitivity analysis. Clamped spherical caps under pressure loading and clamped truncated hemispheres under axial tension were investigated. Buckling loads were determined for axisymmetric and nearly axisymmetric loads and are compared with previously published analytical results based on geometric imperfections.
Stilwell, W. C.↗
Mariner 7 ultraviolet spectrometer experiment - Photometric function and roughness of Mars' polar cap surface.
Review of some of the results of the Mariner 7 ultraviolet spectrometer observations of the south polar cap of Mars. The near ultraviolet polar spectrum shows the predominance of surface reflection over atmospheric scattering. The intensity of the reflected radiation decreased steeply for a change in solar elevation of only about 10 deg. Neither a haze layer nor ground inhomogeneity is considered a likely explanation for this observation. An unusual photometric function of the surface is more probable. An analysis of reflected radiation intensity as a function of incidence and emission angles was made, assuming a photometric function for the surface. The angular inversion revealed a 'smoothness factor' suggestive of an icy or glazed surface. A hypothesis is advanced to explain the observed phenomena and associated polar features.
Pang, K.↗
Critical component of the interplanetary magnetic field responsible for large geomagnetic effects in the polar cap.
An observed influence of the interplanetary magnetic-sector structure on the geomagnetic variations in the polar cap appears to be due to the component of the interplanetary magnetic field near the ecliptic perpendicular to the earth-sun direction. This suggests that the observed effect on the ground originates in the front of the magnetosphere.
Friis-Christensen, E.↗
Polar-cap electric field distributions related to the interplanetary magnetic field direction.
Data from successive Ogo-6 passes over southern and northern high latitudes are presented to illustrate how grossly asymmetric the distribution of electric field magnitudes can sometimes be. They are also shown to provide an example of the anticorrelation between southern and northern polar-cap magnitude distributions. Signature classification, correlations, and possible relations with interplanetary magnetic fields are discussed.
Heppner, J. P.↗
Critical component of the interplanetary magnetic field responsible for large geomagnetic effects in the polar cap
An observed influence is studied of the interplanetary magnetic sector structure on the geomagnetic variations in the polar cap which appears to be due to the component of the interplanetary magnetic field near the ecliptic perpendicular to the earth-sun direction. It is suggested that the observed effect on the ground originates in the front of the magnetosphere.
Friis-Christensen, E.↗
The relation between the azimuthal component of the interplanetary magnetic field and the geomagnetic field in the polar caps
The recently discovered relation between the azimuthal component of the interplanetary magnetic field and magnetic variations in the earth's polar caps is reviewed. When the IMF azimuthal component is positive (typical of an interplanetary sector with magnetic field directed away from the sun) geomagnetic perturbations directed away from the earth are observed within 8 deg from the corrected geomagnetic pole. When the IMF azimuthal component is negative (typically within toward sectors) the geomagnetic perturbations are directed towards the earth at both poles. These perturbations can also be described by an equivalent current flowing at a constant magnetic latitude of 80 - 82 deg clockwise around the magnetic poles during toward sectors and counterclockwise during away sectors. This current fluctuates in magnitude and direction with the azimuthal component of the IMF, with a delay time of the order of 20 minutes. The importance of this effect for understanding of both solar magnetism and magnetospheric physics is stressed in view of the possibility for investigating the solar sector structure during the last five sunspot cycles.
Svalgaard, L.↗
Pulsar magnetospheres, braking index, polar caps, and period-pulse-width distribution.
An investigation is conducted concerning the trapping of gas and its effect on the structure of the magnetic field. The aligned and orthogonal cases are discussed in detail. In each case, there are small collection zones which are both microscopically and macroscopically stable. By determining where macroscopic stability changes to instability, the separatrix between closed and open field lines is investigated together with the sizes and shapes of the polar caps. This information makes it possible to reexamine the period-pulse-width distribution and to compare it with observational data.
Roberts, D. H.↗
Polar cap magnetic variations and their relationship with the interplanetary magnetic sector structure.
The relationship between polar geomagnetic variations and the polarity of the interplanetary magnetic sectors has been studied for the quiet year 1965. It is found that during the day hours a system of ionospheric currents encircles the magnetic poles on every day. The current system may extend up to 15 deg from the pole but is strongest at 8 to 10 deg invariant colatitude. The current direction as seen from near the magnetic poles is counterclockwise during interplanetary sectors with field pointing away from the sun and clockwise during toward sectors. The current strength is dependent on season, being strongest during local summer. When the magnetic pole is on the nightside of the earth, this polar cap current is absent or very weak.
Svalgaard, L.↗
Polar cap on Europa.
Photoelectric observations are reported of two occultations of Jupiter's satellite Europa by the satellite Io. The reductions in the intensity during these events exceeds predicted values by 80% and 55% for the nights of June 17, 1973, and June 24, 1973, respectively. It is concluded that Europa has a bright polar cap extending from the north pole to latitude 30 deg. The light curves for the Europa occultations are presented.
Murphy, R. E.↗