摘要:

The interaction of a satellite with the magnetic field of the earth and the ionized medium through which it is moving has been investigated. Owing to the differing incident velocities of ions and electrons and therefore differing incident flux intensities, a negative potential will be induced on the satellite, but it is smaller than has previously been believed. Satellite motion across the magnetic lines of the earth will induce a voltage on the satellite of as much as 0.2 volt per meter of satellite size, and this may affect the interpretation of measurements of satellite potential. The magnetic drag resulting from the induced currents is proportional to the cube of the satellite dimensions and may exceed the mass drag for satellites larger than 50 meters in diameter; this can occur only above 1200‐km altitude, where the charge density exceeds the neutral density. Thus the magnetically induced current is an insignificant cause of drag. Although some useful power can be extracted from the induced current, it is not a very promising source of auxiliary power for presently conceived vehicle

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00001

年代:1960

数据来源: WILEY

摘要:

Density values of the upper atmosphere derived from the rate of development of the orbits of earth satellites suffer from errors introduced by uncertainties in the determination of the mean drag cross section. As a result it is difficult or impossible to detect minor variations in the density such as, for example, its latitude dependence. An analysis is developed which circumvents this difficulty by considering the behavior of a dynamically simple parameter—the square of the product of the semimajor axis and the eccentricity. Examples from published orbital data are discussed, showing clearly the presence of a latitude dependence, and estimates of the ratio of polar to equatorial density are deduce

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00009

年代:1960

数据来源: WILEY

摘要:

From an analysis of the cosmic‐ray intensities recorded at Mt. Washington, Mt. Norikura, and Huancayo from 1954 to 1958, the long‐term variation of intensity is interpreted as occurring in several sudden decreases rather than gradually. The largest changes of cosmic ray intensity and in the ratios of intensities recorded by the three detectors followed the occurrence of large Forbush‐type decreases. The depressed intensity following the rapid decrease of July 11, 1959, further supports this interpretation. Frequency distributions of the changes in nucleonic intensity from day to day show the importance of the Forbush decreases to the long‐term variation. These results are discussed in terms of possible solar modulating mec

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00019

年代:1960

数据来源: WILEY

摘要:

An analysis has been made of the cosmic‐ray data recorded by the IGY network of stations during the sudden decrease of intensity on February 11, 1958. The unusual rapidity of the decrease, which was followed by a temporary recovery, provides a critical test for existing solar‐controlled modulating mechanisms. The main decrease, occurring practically simultaneously over the earth, was relatively energy‐insensitive. The subsequent temporary recovery appeared to be associated with a spatial anisotropy. It is suggested that these variations can be interpreted as the result of disordering the outer geomagnetic field by the solar wind, as first pointed out by P

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00027

年代:1960

数据来源: WILEY

摘要:

The theory of geomagnetic effects on cosmic radiation is discussed for the case in which the point of observation is above the surface of the earth. Parts of the older geomagnetic theory are readily modifiable for application under the new conditions; the manner in which ordinary Störmer theory and the Lemaitre‐Vallarta theory of the main cone can be adapted is discussed. However, the simple shadow cones of Schremp appear now in a new light; as the point of observation rises from the earth, the simple shadow effect which exists at the earth makes a smooth transition to a new kind of earth's shadow effect. Associated with this effect are principal shadow cones which are defined by reference to the properties of certain families of trajectories. For observation points above the earth a modification in our view of the penumbral region is required; this is discussed very briefly. Extensive computations of principal shadow cones have been carried out by machine integration of the equations of motion and subsequent abstraction of data from these trajectories. Sample computed cones are given for representative particle rigidities, geomagnetic latitudes, and altitudes of observation. The centered dipole approximation for the magnetic field of the earth is used througho

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00039

年代:1960

数据来源: WILEY

摘要:

A survey magnetometer carried aboard the Air Force Pioneer I space probe obtained data over the interval 3.7 to 7 and 12.3 to 14.8 geocentric radii. The day was unusually quiet magnetically (AP∼ ) with a long quiet prior history. The data indicate an inverse‐cube‐field decrease in the region of 3.7 to 13.6 radii, where termination takes place, with a subsequent decrease to 5×10–5gauss. This value is examined in the light of possible interplanetary gas activity. The surprisingly distant geomagnetic cutoff suggests a very low gas pressure on the day of the flight. Increasingly large (fractionally) fluctuations were observed with increasing radii. A gross variability in the vestigial field would suggest hydromagnetic activity or a complex gas cloud s

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00055

年代:1960

数据来源: WILEY

摘要:

Characteristics of the upper‐air magnetic field and ionospheric currents are determined through an analysis of published rocket data on the magnetic scalar intensity. For the region between the earth's surface and theElayer of the ionosphere, the observed values are compared with values obtained by extrapolating the surface vector field. The agreement between the two sets of values is very good for equatorial flights but only fair for a flight at White Sands, New Mexico. The equatorial, ionospheric current density, which has a maximum of about 21 amp/km2, varies considerably with time and location of the rocket flight. The equatorial electro jet has a current intensity of about 130 amp/km and flows practically along the magnetic equator. Some of the computed currents associated with the normal magnetic daily variation are at variance with those expected from considerations, such as harmonic analysis, of the surface transient field and sheet‐current approximations. In the area around White Sands (geomagnetic latitude 41°N) a large negative magnetic anomaly exists that may contribute to the formation of the region of low intensity of radiation that lies between the two Van Allen radiation b

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00069

年代:1960

数据来源: WILEY

摘要:

Rapid‐run magnetograms from the U. S. Coast and Geodetic Survey (USC&GS) and from other observatories located near the magnetic equator were used to study sudden commencements that occurred during the period October 1957 to September 1958. Analysis of these magnetograms yielded three important results: (1) the sudden commencement always occurred first in high or middle latitudes; (2) Little America, Antarctica, registered the sudden commencement first or second 85 per cent of the time; and (3) the apparent propagation velocities of the sudden commencement around the magnetic equator had average values between 1145 and 2835 km/se

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00085

年代:1960

数据来源: WILEY

摘要:

A discussion of the two‐gas theory of the transmission of geomagnetic disturbances through the atmosphere (to several earth radii) is extended, with the following results: (i) The central problem concerning the main phase of a geomagnetic storm is the mechanism of penetration of solar ions into the geomagnetic field. An explanation is given depending on a combination of a uniform electric space‐charge field and a system of irregular fields. (ii) A model of the main phase of a geomagnetic storm is given, the principal feature of which is a ‘magnetic tail’ extending from the earth on the dark side. (iii) The model may help to explain some other effects: the Gegenschein, electrons with auroral energies, the location of the Van Allen zones, and diurnal cosmic‐ray variations, (iv) All observed geomagnetic disturbances have their sourcesinitiallyin current systems in the lower ionosphere. Some are subsequently maintained by current systems in the earth itself and in the region of interaction between the solar and terrestrial plasmas. Others, mainly polar and equatorial, are maintained by ionospheric currents driven by space‐charge electric fields, (v) Any ring current outside the geomagnetic field could cause an increase in the horizontal component. A westward‐flowing ring current embedded in the field could cause either an increase or a decrease in the horizontal component. The basic effect is not the current but a sustained inward or outward mechanical force on the material in which the

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00093

年代:1960

数据来源: WILEY

摘要:

An analysis of the occurrence frequency of geomagnetic micropulsationsPchas been carried out using data obtained during the IGY from a world‐wide network of stations. From the characteristics of the diurnal occurrence frequency and their latitudinal and longitudinal dependence, the following conclusions are drawn: (1) The occurrence frequency ofPc's increases as the auroral zones are approached from lower latitudes. Also the hour of the diurnal maximum occurrence appears earlier at high‐latitude stations. (2) The occurrence frequency ofPc's depends not only on local time but also in part on universal time. The universal‐time factor affects the modulation of the diurnal occurrence by about 50 per cent. The time of maximum occurrence of PC's is about 21 hours GMT in the northern hemisphere. In the southern hemisphere the universal‐time factor has opposite phase to that in the northern hemisphere. When the universal‐time factor is a maximum in the northern (or southern) hemisphere, the north (or south) geomagnetic pole is about 16 or 17 hours LMT. The GMT dependence derived in this investigation shows about 7 hours' difference compared with Troitskaya's conclusion, which was based on data from several stations in the USSR.This article contains supplementary

ISSN:0148-0227    

DOI:10.1029/JZ065i001p00107

年代:1960

数据来源: WILEY