On the possibility of inferring the inter-planetary sector structure from daily variations of geomagnetic ap indices

Schreiber, Hermann

doi:10.1016/0032-0633(78)90007-7

Cited by 3 publications

(2 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the southern hemisphere the same story holds for Z, but the sign reverses for H. The early analyses were done by visual judgment of the geomagnetic variations [e.g., Svalgaard, 1972], but Campbell and Matsushita [1973] and Campbell [1976] examined the relation objectively by an automated computer technique and concluded that a fairly good correlation can be obtained mainly in local summer. Also, Schreiber [1978] discussed the possibility of inferring IMF sector structures from daily variation patterns of 3-hour ap values, while Mori and Nagashima [1979] inferred sector polarities from cosmic ray north-south asymmetries.…”

Section: Introductionmentioning

confidence: 99%

IMF sector behavior deduced from geomagnetic data

Matsushita¹,

Trotter²

1980

J. Geophys. Res.

View full text Add to dashboard Cite

Interplanetary magnetic field (IMF) sector structures, such as 'toward' the sun and 'away' from the sun on each day, have been objectively estimated from daily and monthly mean values of the horizontal component of the geomagnetic variation field at Godhavn during the period 1926-1970. The agreement between this estimation and actual satellite observations of the sector structures of the interval 1964-1970 is 88, 79, and 58% in summer, equinox, and winter, respectively. A remarkable agreement (more than 95%) is obtained for the summers of 1964, 1969, and 1970. Various types of IMF sector behavior are examined by taking this seasonal factor into consideration. Approximately 27-day recurrences of the same structure are often found, and 5-to 14-day consecutive occurrences of the same sector are frequently noted. Furthermore, the total number of occurrences for each estimated sector in each year shows an apparently good correlation with smoothed sunspot numbers and geomagnetic aa index. After a brief introduction of the production mechanism of sector effects on polar geomagnetic fields the limitations and merits of IMF sector inference from geomagnetic data are emphasized. % % % %

show abstract

Section: Introductionmentioning

confidence: 99%

IMF sector behavior deduced from geomagnetic data

Matsushita¹,

Trotter²

1980

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…It also has been shown that``a basic variability of the sector structure becomes apparent with characteristic times on the order of a few years'' (Gonzalez and Gonzalez, 1987) and that the fundamental period changes from 28 to 27 days according to the phase of the solar cycle. For our analysis we used the IMF polarity inferred from the daily variation of ap, which was found to give reasonable results for statistical purposes (Schreiber, 1978). In Fig.…”

Section: The 27-day Variationmentioning

confidence: 99%

On the periodic variations of geomagnetic activity indices Ap and ap

Schreiber

1998

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. Yearly averages of geomagnetic activity indices Ap for the years 1967±1984 are compared to the respective averages of m 2 Á f s , where v is the solar wind velocity and f s is the southward interplanetary magnetic ®eld (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap with m 2 and f s separately we ®nd that, during the declining phase of the solar cycle, m 2 and during the ascending phase f s have more in¯uence on Ap. According to this observation (using Fourier spectral analysis) the semiannual and 27 days, Ap variations for the years 1932±1993 were analysed separately for years before and after sunspot minima. Only those time-intervals before sunspot minima with a signi®cant 27-day recurrent period of the IMF sector structure and those intervals after sunspot minima with a signi®cant 28±28.5-day recurrent period of the sector structure were used. The averaged spectra of the two Ap data sets clearly show a period of 27 days before and a period of 28±29 days after sunspot minimum. Moreover,

show abstract

Recent progress in studies of magnetospheric storms and substorms.

Akasofu

Kamide

1980

J. geomagn. geoelec

View full text Add to dashboard Cite

We have made various degrees of progress during the last two years in the areas covered by Topic III-6, Magnetic Storms and Substorms, including Aurora-Magnetospheric Relations. The finding of the V-potential structure above the auroral oval was certainly an important milestone in the history of magnetospheric research. The relationship between field-aligned currents and ionospheric currents has become increasingly clear during the last few years. Extensive attempts have been made to understand how the solar wind couples its energy to the magnetosphere and to find the expression for the rate of input energy from the solar wind to the magnetosphere. On the basis of this progress, a new model of the solar wind-magnetosphere relationship has begun to emerge.The interpretation of observed magnetotail phenomena is still very confusing. Some of the problems associated with this confusion are discussed. Decisive observations to identify the basic processes associated with the "injection" of ring current particles have not been made. However, the finding of 0 ions in the ring current belt was an exciting event during the last two years.

show abstract

On the possibility of inferring the inter-planetary sector structure from daily variations of geomagnetic ap indices

Cited by 3 publications

References 19 publications

IMF sector behavior deduced from geomagnetic data

IMF sector behavior deduced from geomagnetic data

On the periodic variations of geomagnetic activity indices Ap and ap

Recent progress in studies of magnetospheric storms and substorms.

Contact Info

Product

Resources

About