摘要:

The 24‐hour and 12‐hour waves in cosmic‐ray intensity at Cheltenham (Fredericksburg), Huancayo, and Christchurch and their variability are analyzed statistically, using data, corrected for pressure, for the period 1937–1959 from Compton‐Bennett ionization chambers. The degree of correlation between the deviations of yearly mean 24‐hour waves (from their 23‐year means) at any two of the stations is almost as great as can be expected when account is taken of the noise level inherent in the instruments. The deviations of yearly means, from their 23‐year averages, indicate large secular variations which may be due to a quasi‐systematic 22‐year variation. The phase difference between these yearly deviation vectors at Huancayo and Cheltenham (or Christchurch) is considerably less than that between the average vectors for 23 years. The statistical reality of the 12‐hour wave is definitely established at all three stations, although, at least at Huancayo, the average 12‐hour wave probably results entirely from systematic errors due to exceedingly small frictional e

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02213

年代:1960

数据来源: WILEY

摘要:

Atmospheric pressure at 200 km must be nearly constant over the entire earth as a result of large‐scale air motions which can occur in the ionosphere. In the lower atmosphere, adjacent areas of high and low pressure can exist without annihilation by pressure equalization; direct air flow from high to low pressure does not occur, because balanced circulations develop in which inertial forces (centrifugal and Coriolis) balance the pressure forces and prevent equalization. At altitudes near 200 km, viscous forces prevent the balanced circulations from occurring, so pressure equalization can proceed rapidly. The heat transport associated with the air motion is large and tends to bring about temperature equalization also. At still higher altitudes, the heat content and the pressure forces are smaller but the viscous forces for a given velocity shear remain unchanged, making possible the existence of pronounced high‐pressure areas in regions of local heating. The conclusion reached in this study does not permit one to accept the frequently held concept that the polar or auroral zone ionosphere is much warmer than the equatorial ionosphere with pressures at 200 km several times larger in the polar regions (e.g., at Churchill, Canada) than at temperate and low altitudes (e.g., at White Sands, New Mexi

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02227

年代:1960

数据来源: WILEY

摘要:

The Argus detonations in the ionosphere above the south Atlantic produced geomagnetic disturbances that propagated to almost all parts of the world. The geomagnetic variations, having a quasi‐period of 1 to 3 seconds, were recorded principally by induction‐type magnetometers and earth‐current stations. We found two signals whose indicated velocities were of the order of 3000 and 700 km/sec. Amplitudes varied from 5 gammas (Antarctica) down to 0.002 gamma at our large loop in Arizona. The signal strength falls off rapidly as the direction of propagation deviates from the geomagnetic mer

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02233

年代:1960

数据来源: WILEY

摘要:

Increased activity of magnetic micropulsations with periods of 5 to 30 seconds and magnetic flux densities of 20 to 320 mγ was found to accompany the η Aquarid, δ Aquarid, and Perseid meteor showers in 1958. Conflicting reports are discuss

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02241

年代:1960

数据来源: WILEY

摘要:

The electrostatic characteristics associated with the equatorial electro jet are investigated with the aid of a number of theoretical and experimental considerations. With regard to the peak electro jet current, an eastward component of electric force of magnitude 4×10−4volt/meter drives a current of density 10−5amp/meter2. In the region of maximum current the ionosphere is electrically neutral, but the electric field is created by an electrostatic charge distribution with an excess of electrons in the region east of the point with peak current and an excess of positive charges in the region to the west. The maximum of the difference in the number density of the negative and positive charges is 5×10−2charge/ meter3for the volume density, and 9×104charge/meter2for the surface density on the lower boundary of theElayer. These number differences, which represent extremely small departures from electrical neutrality in the ionosphere, indicate the prime importance of a surface charge distribution in producing the ionospheric electrostatic field. The vertical component of the electrostatic force has a maximum value of 4×10−4volt/meter but vanishes at the point containing the peak electro

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02247

年代:1960

数据来源: WILEY

摘要:

The IGY records taken on the 41‐Mc/s auroral radar at Ithaca have been compared with visual observations. It appears that the radar consistently detects auroras between 500 and 1200 km north of Ithaca and can therefore be used to study auroral statistics in this region. Specific studies have been made of the latitude distribution and the diurnal distribution. Many unidentified, nonauroral echoes are presen

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02255

年代:1960

数据来源: WILEY

摘要:

Simultaneous auroral echoes at 49.7, 143.5, and 226 Mc/s have been recorded using scaled radar equipments. Analysis indicates that the wavelength dependence of auroral echoes varies from λ3.5for frequencies of 49.7 and 143.5 Mc/s to λ6.5for frequencies of 143.5 and 226 Mc/s. These measurements are in reasonable agreement with Booker's theory of auroral echoes if the scale sizes (measured transverse to the magnetic field) are taken as roughly 40 cm. Evidence for nondeviative absorption at 50 Mc/s is also adduce

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02261

年代:1960

数据来源: WILEY

摘要:

To explain spread echoes from theFregion the concept of aspect sensitivity was incorporated in our derivations ofh′fcurves using the assumption that the magnetoionic components can be treated separately. The shape of theh′fcurves, as well as the extent of range and frequency spreading, was deduced for ionospheric stations located at various magnetic latitudes. The requirements of aspect sensitivity restrict the solid angle containing the echo rays to a wedge with its apex line running east‐west through the transmitter location and with its angle determined by the dip angle. At the magnetic north the wedge opens flat, and at the magnetic equator the wedge degenerates into an east‐west flat fan. The model does not lead to an explanation of a large class of observed spreadFin the northern and middle latitudes. At the magnetic equator, however, the model is potentially capable of clarifying the observed spreadFof a type shown in thi

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02269

年代:1960

数据来源: WILEY

摘要:

Using formulas developed in previous papers [Gliddon, 1959a and b;Gliddon and Kendall, 1960], we obtain quantitative results for the diurnal variation of electron density in theF2region, taking account of diffusion and of an exponentially decreasing attachment‐type law of recombination. The atmosphere is assumed to be isothermal, and for the case considered here (middle latitude) the effect of the geomagnetic field on diffusion is small enough to be ignore

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02279

年代:1960

数据来源: WILEY

摘要:

Ionospheric absorption (L) at high latitudes is studied using the published data on 2.0 Mc/s at five Canadian stations during 1957 and 1958. The seasonal and diurnal variations are considered, and it is found that a pronounced winter anomaly in noon absorption occurs at Churchill but not at Resolute Bay. The diurnal variations indicate that the dependence of absorption on solar zenith angle decreases with increase of latitude. The distribution of midnight absorption with latitude shows that, although the maximum occurs in the auroral zone, high absorption is also encountered over the polar cap. A study of the duration of long‐lasting blackouts shows that in summer the duration is longer as the latitude increase

ISSN:0148-0227    

DOI:10.1029/JZ065i008p02285

年代:1960

数据来源: WILEY