摘要:

The drift of theE‐layer diffraction pattern on the ground has been recorded at Kjeller (ϕ = 59° 58′ north, λ = 10° 06′ east) on 2 Mc/s during the period of June 1953 to September 1955.Three receiving points were put up and the amplitudes of theE‐echoes were recorded (Mitra method). The time shifts between the maxima in the fading curves were recorded automatically by means of a Phillips recorder, or, optically on a three‐beam oscillograph.The mean diurnal values of the east–west and north–south components of the drift in meters per second have been given for the seasons—winter, spring, summer, and autumn. The seasonal and annual curves have been analyzed and the mean values compared with the results from similar recordings at Cambridge, Washington, and Ottawa. There is a constant term indicating a prevailing drift towards southwest in winter and towards northeast in summer. There is a solar 12‐hour term appearing during all seasons of the year. The mean annual values of phase and amplitude of this term at Kjeller are very similar to the corresponding term at Cambridge. The summer values have been analyzed for a lunar term, and a small but doubtful component has appeared.During daytime, there is no systematic change in the wind‐directions on days withEsor normalE. At sunset, when the electron density of the normalE‐layer is too low for reflecting the test frequency 2 Mc/s, there is a sudden change in the direction of the east–west component. TheEs‐layer recorded after sunset and during the night has a strong westerly component. On account of the width of the gate, it is not possible to decide if this is a height effect. Another explanation is that the diffraction pattern during night‐time is not isotropic, but has a preferred orientation in north–south direction. This will simulate a strong increase in the east–west component of the drift.It is pointed out that the probability distribution along the north–south direction is systematically narrower than along the east–west direction. Examples of very narrow probability distribution in north–south direction at night are given. The conclusion to be drawn is that there seems to be a preferred orientation in north–south direction of the lines of maxima during daytime, which durin

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00183

年代:1957

数据来源: WILEY

摘要:

An analysis of hiss recorded during a magnetic storm shows that the spectrum peaked near 3 kc, that the high frequency limit was variable during the period, and that a curious procession of narrow band‐width tones gliding upward occurred during part of the perio

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00199

年代:1957

数据来源: WILEY

摘要:

Some photochemical processes which may be thought of importance for the emission of the sodium lines in twilight and nightglow are discussed. Na + O2+M→ NaO2+Mis taken to be the most important oxidation process. Lack of information about the rate coefficients involved prevents precise quantitative computations, but it is found that photochemical reactions may explain the formation of the emitting layers and the nightglow intensity. However, no satisfactory interpretation of the large seasonal variation has so far been given. Photochemical reactions, as well as photoionization of sodium, seem insufficient to explain the observation

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00207

年代:1957

数据来源: WILEY

摘要:

By preparing bases for a Rude Star Finder with various astronomical coordinate systems on them, it is possible to convert points in the horizon system of altitude and azimuth into points in the astronomical system of right ascension and declination, or into points in the ecliptic and galactic systems of latitude and longitude. The device may also be used to solve terrestrial problems, such as distance and bearings between two points on the earth. Bases for the astronomical‐terrestrial, ecliptic, and galactic coordinate systems and one calibrated in integrated starlight are presente

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00213

年代:1957

数据来源: WILEY

摘要:

The downward flux of atmospheric ozone near the earth's surface is evaluated from recordings in Nebraska of the vertical profile of ozone and from simultaneous data on the wind profile and on the shearing stress at the surface. Furthermore, recordings of the ozone concentration in New Mexico at two levels which are 4,000 feet apart in altitude are used, together with the previously determined flux value, for an estimate of the coefficient of exchange in the atmosphere between the two stations. The observed differences in the ozone concentration at the two stations are also examined in relation to wind and temperature.

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00221

年代:1957

数据来源: WILEY

摘要:

The results of observations of cosmic noise at frequencies of 10.05, 5.65; 4.4, and 3.8 Mc/s are reported. At the three highest frequencies, half‐wave dipole aerials were used, while at 3.8 Mc/s the aerial system was an array with a beam‐width of 50° by 26°. In addition, previous observations at 2.13, 1.43, and 0.9 Mc/s have been reassessed.It was found that the increase in the intensity of the radiation with decreasing frequency ceases at about 10 Mc/s, and that the spectrum is flat between 10 Mc/s and 2 Mc/s, and possibly to 0.9 Mc/s. The flux density of the radiation at these frequencies is approximately 2×10−19watt/m2(c/s)−1, the equivalent temperatures varying from 6×105degrees at 10 Mc/s to 3×107degrees

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00229

年代:1957

数据来源: WILEY

摘要:

It is shown that the most likely cause of discrepancies between the agestof archeological specimens determined from radiocarbon measurements and the corresponding actual agest′ is a long‐period variation in the magnetic dipole momentMof the earth. The relationshipis obtained. Comparison with the limited data available shows that, between roughly 5,000 and 15,000 years ago, any changes inMthat persisted for times of the order of several thousand years could not have exceeded about 10 per cent of the mean value ofMin that interval. Shorter‐period fluctuations could have been greater, particularly if oscillatory variations occurred. The approximate agreement between the current rate of production of radiocarbon and the mean rate necessary to account for the existing radiocarbon inventory extends this conclusion down to the present day, excluding the possibility that any major, long‐term changes in the magnitude of the earth's magnetic field took place in the past ∼ 15,

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00235

年代:1957

数据来源: WILEY

摘要:

In previous papers (Hope [7, 16]), the rotary motion of the magnetic needle as displayed in Bauer's curves of secular variation (Fig. 1) has been discussed on a descriptive basis. The present paper is an attempt to discuss the mechanism, and to relate it to the general westward drift of the surface geomagnetic field. The interpretation of the spherical harmonic analyses is considered. The essential conclusion is that the drift‐rotation of the surface of the terrestrial core must be zonal, like that of the solar surface. This conclusion aids in accounting for the Bauer rotatio

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00241

年代:1957

数据来源: WILEY

摘要:

The scattering of VHF radio waves in the lower ionosphere is identified with turbulent fluctuations of the electron plasma. The theory of gradient mixing is applied to the afternoon and early evening periods, for which solar control is thought to dominate meteoric contributions. The scattering cross‐section for this process,depends on ionospheric conditions only through the ambient electron density‐height profile's gradient dN/dh. It is found that the afternoon decay of signal strength and simultaneous increase of scattering height can be correlated with independent estimates of electron density and recombination coefficients in the lower ionosphere. The observation of two scattering levels on short paths and the lack of a midday maximum on long paths is predictable. Diurnal variations of the frequency dependence of these transmissions suggest a strong influence of the earth's magnetic fi

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00255

年代:1957

数据来源: WILEY

摘要:

The dependence of noise, and particularly noise as a function of frequency, on the operating conditions of the transistor is investigated. A transistorized preamplifier with noise low enough to enable it to be used down to ground displacements of 10−9cm with seismometers whose output is 5 ω volts/cm is describ

ISSN:0148-0227    

DOI:10.1029/JZ062i002p00267

年代:1957

数据来源: WILEY