摘要:

The accompanying papers were among those presented at the first International Symposium on Equatorial Aeronomy, held at Hotel Huaychulo, near Huancayo, Peru, from September 18 through 25, 1962. A summary session was held in Lima on the morning of September 27, 1962.The field now known as ‘equatorial aeronomy’ refers to studies of the atmosphere in the vicinity of the magnetic equator. In particular, inasmuch as charged particles interact with the earth's magnetic lines of force, the geometry of the equatorial magnetic field leads to many interesting ionospheric and magnetic phenomena. Many workers all over the world have been studying the equatorial ionosphere for some time. Although considerable information has been accumulated, many mysteries still remain. However, there had never been a conference devoted exclusively to equatorial aeronomy (as there had been for polar aeronomy, for example). The need for such a conference was recognized in 1959, and this symposium was held three years la

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02359

年代:1963

数据来源: WILEY

摘要:

A correlation analysis of spaced aerial fading measurements for medium‐frequency radio waves scattered from theDandEregions at a location near the magnetic equator is reported. The results show that there is a slight tendency towards field‐aligned elongation of the diffraction pattern on the ground for echoes from 80 and 90 km and considerable elongation for echoes from above 90 km. It is shown that ambipolar diffusion processes would become anisotropic at this height, which could lead to the elongation of the irregularities in the ionosphere responsible for the diffraction pattern on the gro

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02363

年代:1963

数据来源: WILEY

摘要:

It is shown that the zenith‐angle dependence of ionospheric absorption is profoundly affected by the nature of the height variation of the recombination coefficient in the lower ionosphere. Computations for some assumed distributions of the recombination coefficient are give

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02367

年代:1963

数据来源: WILEY

摘要:

It is shown that the growth of auroral electrojects can greatly enhance the equatorial electro jet. This indicates that a part of the return current, spreading from the auroral zone to the ionosphere in low and middle latitudes, can extend to as far as the late afternoon side along the magnetic equator. The current systems inferred so far for polar magnetic substorms may have to be revised to include such an intense return current. The enhancement is used to infer the distribution of the highly conductive region along the magnetic equator. It is shown that the conductivity is about 4–7 times higher there than in middle latitude

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02375

年代:1963

数据来源: WILEY

摘要:

We consider briefly the possibility that electrical linkage, through the exosphere, between magnetically conjugate points, may influence the dynamo currents. A very rough estimate suggests that the effect is worthy of quantitative study.

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02383

年代:1963

数据来源: WILEY

摘要:

Two magnetic variometers have been continuously operated at comparable longitudes at Baguio and Cebu, Philippines, 900 and 300 km north of the magnetic equator, respectively. An attempt has been made to separate the electrojet contributions to the monthly mean of the daily range inHandZ. The jet appears to change its form with the season. The overhead disturbance currents appear north of Cebu at night, but south of Cebu during the day. Micropulsations, of peak‐to‐peak amplitude of 1 γ or greater, have a nonzero occurrence probability at any hour, with a maximum at local noon and a secondary maximum about midnight.The Johnston Island July 9, 1962, disturbance effects on the Philippine magnetic traces are prese

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02385

年代:1963

数据来源: WILEY

摘要:

TheSDvariations of the horizontal and vertical magnetic elements of the earth's magnetic field at nine mid‐ and low‐latitude stations and of the earth‐current components at Legon, Ghana, are presented and discussed. For stations in the region of the equatorial electrojet in Africa, theSDvariations differ considerably from those at midlatitudes. The difference between the equatorialSDand the midlatitudeSDis found to consist of variations with a midday maximum inHand a midday minimum inZ. This finding suggests that there is either (a) an additionalSDcurrent near the magnetic equator or (b) an increase in the strength and width of the equatorial electrojet during magnetic disturbance. Also the earth‐currentSDvariation is found to agree reasonably well with the derivative of theSDvariation of the total

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02395

年代:1963

数据来源: WILEY

摘要:

The harmonic coefficients of the earth‐current variations at two stations in Ghana are presented and discussed. The ratio of the two principal harmonics of the variations at Legon are found to exhibit a seasonal variation, which is interpreted as arising from a shift in the position of the electrojet axis. Chapman and Whitehead's expressions relating earth‐current variations with variations of the magnetic field are discussed, with reference to corresponding relations deduced by Tikhonov and Lipsk

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02403

年代:1963

数据来源: WILEY

摘要:

The daily variation of geomagnetic vertical intensity (Z) at Koror, Palau Islands, slightly south of the dip equator, is characterized by a positive salient before 1100 hours and a negative one after 1500 hours. This feature, which persists throughout the year, appears to reflect a component of theZcurve that simulates the time derivative of the horizontal‐intensity (H) curve. A similar though less pronounced effect may be discerned at Huancayo and at Trivandrum; at Addis Ababa its sign is reversed. This component probably makes inapplicable to Koror (and possibly to some other localities) the suggestion advanced by Osborne that the day‐to‐day fluctuations in the ratio ofZandHranges in western Africa may reflect shifts in the latitude of the electrojet. To account for the observedZeffect it is suggested that there is superimposed on the conventionalSqpattern of ionospheric currents a north‐south flow of current confined to the daylight side of the earth, that this current reverses its sign in a systematic relation with the earth's rotation, and that it may tend to channelize along the paths established by theSqpatterns, so as to become manifest in the daily‐variation curves at stations in higher latitudes as well as along the dip equator. On the basis of the relative amplitudes of the eastward and westward salients of magnetic declination curves, the suggestion is strongly supported as regards Europe and the western hemisphere; but equivocal results are obtained for Australasia and the western Pacific, notwithstanding that Koror in this region exhibits theZeffect more strongly than any other equatorial station. Neither the source of the postulated current nor the path by which its circuit is completed is clear. It is conjectured that a persistent leakage of charged particles trapped in the magnetosphere, falling from their mirror points into the upper air, may give rise to vacillating potential differences between the northern and southern auroral zones, and that the phenomena here reported represent the ebb and flow of ionospheric current required to equalize these potential di

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02411

年代:1963

数据来源: WILEY

摘要:

Photographic records of the daily variations of the magnetic elementsH, DandZwere taken at 10 stations across the magnetic zero dip equator in Nigeria around the June solstice (May to July) 1962. A preliminary analysis of these records locates the axis of the equatorial electrojet on the magnetic equator (10.2°N latitude in Nigeria), and there the average daily range ofZwas practically zero. On the model of a uniform current band at a height of 110 km the equatorial electrojet in this season was found to have a width of (406±20) km and a current intensity of 116 amp km−1. These values are compared with other existing values they show clearly that both the width and the intensity of the electrojet have decreased with decrease in solar activ

ISSN:0148-0227    

DOI:10.1029/JZ068i009p02421

年代:1963

数据来源: WILEY