摘要:

In a dipole field, many different invariant shells (I, Bm) share exactly the same lines of force. These invariant shells are therefore members of a degenerate system. In the geomagnetic field, which is assumed static and without electric field, these degenerate systems are split by azimuthal asymmetry. A distinction is made, therefore, between the use of parameters as invariants of charged particle motion (invariant representation) and their use as constants for all particles on a line of force (degenerate representation). We find that McIlwain'sLvalue associates nondegenerate geomagnetic shells with dipole degenerate systems ifLat a point in space is redefined to apply only to particles mirroring at that point. Emphasis is placed on the redefinedLas an invariant parameter of particle motion and on the near equality of theLvalue of a particle and the equatorial radiusR0of the line of force on which the particle is mirroring. Although the original definition ofLresulted in a very useful parameter, the present definition allows a physical interpretation ofLas originally applied and extends its usefulness beyond that allowed by the original definition. With the present definition, the different values ofLalong a line of force can be identified with the radial separation of particles mirroring on that line as they drift in longitude. This separation is ≈2 per cent of the shell radius and represents the accuracy with which a single magnetic field parameter, such as the minimum field intensityB0of a line, describes all particles on the line (a degenerate representation). Beyond 3 earth radii, it is found thatR0gives a representation of comparable accuracy. However, an invariant representation (L, Bm) or (I, Bm) is limited only by the accuracy of the determination of the mirror fieldBmand the longitudinal invariantI, both of which depend on the accuracy of the magnetic field representatio

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04157

年代:1963

数据来源: WILEY

摘要:

From a comparison of X‐ray, ionospheric absorption, and geomagnetic observations during an intense electron precipitation event in the auroral zone, it is shown that the distance scale for motions of electrojet‐electron precipitation regions is smaller than previously considered. This requires a downward revision of the correction factors for currents induced in the earth by ionospheric current syst

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04167

年代:1963

数据来源: WILEY

摘要:

An examination of solar illumination effects for auroral absorption events centered over the 27.6‐Mc/s riometer antenna pattern at College, Alaska, shows that the daynight absorption ratio is essentially unity. This finding indicates that electron‐positive ion recombination far outweighs electron attachment processes in auroral absorption regions and is consistent with present knowledge of the electron bombardment as well as ionic‐molecular processes at the 90‐100‐km level. Further implications of this result are

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04175

年代:1963

数据来源: WILEY

摘要:

Microwave diagnostic (wave‐guide) methods were used in the study reported here to measure the effective electron recombination rate αrin the afterglow of a pulsed dc discharge as a function of gas temperatureTand pressurepin the ranges 300°K to 735°K and 0.5 mm to 6.0 mm Hg, respectively. It is found that αrhas a value of 1.2×10−7cm3sec−1atT= 300°K andp= 1.0 mm Hg, which is considerably smaller than most previously reported values. Over this temperature range αrdecreased withT, by roughly one order of magnitude atp= 2.0 mm Hg, and more than two orders of magnitude atp= 6.0 mm Hg, the sharpest decrease taking place aboveT= 600°K. The increase of αrwith pressure became smaller as the temperature was raised, ultimately leading to a decrease of αrwith pres

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04181

年代:1963

数据来源: WILEY

摘要:

To generalize the equations for vertically integrated flow tonparameters, it is assumed that the temperature at any level in the model atmosphere is expressible in the form whereT*(p) is a standard temperature distribution andnis the number of layers. It is then possible to derive the corresponding forms for the static stability, the stream function, and the rotational part of the wind. The model equations consist ofnprognostic equations: a vorticity equation for the mean flow and a system of (n— 1) equations for theTi(x, y, t), and two diagnostic equations: a vertical motion equation for the mean flow and the continuity equation for the divergent part of the wind. The barotropic, therm otropic, and three‐parameter models are deducible from the general system. A table is presented showing the number of terms in each equation as the number of parameters is increa

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04187

年代:1963

数据来源: WILEY

摘要:

Unusually intense radioactive fallout of short‐lived fission products was experienced in widespread areas of the United States and Canada during the period September 16 through 22, 1961. The available evidence indicates two radioactive fallout sources in the troposphere: a concentrated debris layer of Soviet test origin observed over Flin Flon, Manitoba, Canada, on September 14–15 and a radioactive cloud source from the vented Nevada underground shot of September 15. The convergence of atmospheric trajectories for these two sources on September 17 and 18 limits the discrimination of the fallout origin at some locations. However, the intense fallout over southeastern and central United States on September 18 and thereafter conforms to the pattern and timing for the September 15 Nevada cloud source trajector

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04195

年代:1963

数据来源: WILEY

摘要:

Analyses for the rare‐earth elements in sea water, in a phosphorite, and in a manganese nodule were made by neutron activation and X‐ray fluorescence techniques. These marine samples showed a depletion, in the heavier rare‐earth elements, relative to chondritic meteorites, beginning with samarium. Cerium was enriched in the manganese nodule, probably as a result of its oxidation to the 4+ valence state. The ratios of the rare‐earth abundances in the two minerals to those of sea water go through a maximum in the vicinity of samarium. The europium concentration, often anomalous in terrestrial minerals, was normal relative to the other rare earths in all of the samples. The sea water showed four times the concentration of rare earths at a depth of 4000 meters as compared with surface

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04209

年代:1963

数据来源: WILEY

摘要:

A total of 194 new measurements of heat flow through the eastern Pacific Ocean floor are presented. They range in value from essentially zero to 8.04×10−6cal/cm2sec. The crest of the east Pacific rise is systematically associated with high values, a strip 200 to 300 km wide at the crest having an average heat flow of about 3×10−6cal/cm2sec. Within this strip, the highest values occur in two narrower zones which appear to be approximately parallel and symmetrically oriented to the crest. The source of the high heat flow in each of these zones is probably a region of unusually high temperature a few tens of kilometers wide located about 10 km beneath the ocean floor. One‐fourth of all the measurements gave low heat‐flow values (≤0.80×10−6cal/cm2sec). Two approximately equidimensional regions near the equator and to each side of the rise show generally low heat‐flow values. These regions are 2 to 4×10−6km2in area, and their average heat flows are about half the normal oceanic value of 1.2 to 1.4×10−6cal/cm2sec. In other areas, many of the isolated low heat‐flow values are correlated with flat topography which suggests an effect of the local environment; these values are presumably not representative of the regional geothermal heat flow. The systematically distributed variations suggest an origin associated with large‐scale therma

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04219

年代:1963

数据来源: WILEY

摘要:

The Hawaii Institute of Geophysics is conducting a study ofTphases received by hydrophones of the Pacific missile range at Kaneohe, Oahu. Arrival times on these records are compared with U.S. Coast and Geodetic Survey epicenter cards for identification ofTphases. During March 1962 a 12‐day listening period showed 81 signals ofT‐phase type. Eight were identified from epicenter cards and eight more from seismograph station reports for which epicenters are not reported in the cards. In 6 days of simultaneous hydrophone recordings at Point Sur, California, and Kaneohe, correlations were found for eightTphases, thereby locating additional sources by delay time. For 1 year's observations, the epicenters associated withTphases have been plotted on large‐scale charts together with epicenters along the Pacific rim for which noTphases were received.Tphases from epicenters at the lower end, and to seaward, of the continental slope are typically weak or not received. This pattern is shown to support the theory of downslope propagation as the mechanism forP‐Ttransformation. Ground arrivals from Hawaii earthquakes are di

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04251

年代:1963

数据来源: WILEY

摘要:

The recent development of seismographs for use on the moon having sufficient sensitivity at long periods to tidal tilts and changes in gravitational acceleration makes possible the determination of gross physical properties of the moon from tidal observations. Theoretical tides (gravity variations and deflections of the vertical) for a rigid moon can be compared with observed tides to obtain the characteristic (Love) numbers,handk, for the moon. Numerical calculations of tides for a 55‐day interval at several locations on the moon indicate: (1) the major perturbing body is the earth—about 1 to 3 per cent is contributed by the sun; (2) three relative motions, distance variation, latitudinal libration, and longitudinal libration, are of equal importance; (3) the relative importance of these three components of motion and relative amplitudes of the three orthogonal components of tidal acceleration are strongly dependent upon location; (4) tidal changes in gravity and tilt are one to two orders of magnitude larger than those observed on ea

ISSN:0148-0227    

DOI:10.1029/JZ068i014p04261

年代:1963

数据来源: WILEY