Secular variations of the geomagnetic field and solar activity

Сделана попытка разделения вековых колебаний, создаваемых внешними источниками, по данным обсерваторий «Нурмиярви», «Лервик», «Ленинград», «Нимек», «Бельск», «Хартланд», «Киев», «Львов», «Шамбон-ля-Форет», «Одесса», «Сурларли», «Коимбра». Показано, что существует три типа вековых колебаний, связанны...

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Дата:	2011
Автори:	Sumaruk, Yu., Reda, J.
Формат:	Стаття
Мова:	English
Опубліковано:	Інститут геофізики ім. С.I. Субботіна НАН України 2011
Назва видання:	Геофизический журнал
Теми:	Научные сообщения
Онлайн доступ:	http://dspace.nbuv.gov.ua/handle/123456789/97101
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Цитувати:	Secular variations of the geomagnetic field and solar activity / Yu. Sumaruk, J. Reda // Геофизический журнал. — 2011. — Т. 33, № 4. — С. 134-141. — Бібліогр.: 8 назв. — англ.

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spelling	irk-123456789-971012016-03-26T03:02:30Z Secular variations of the geomagnetic field and solar activity Sumaruk, Yu. Reda, J. Научные сообщения Сделана попытка разделения вековых колебаний, создаваемых внешними источниками, по данным обсерваторий «Нурмиярви», «Лервик», «Ленинград», «Нимек», «Бельск», «Хартланд», «Киев», «Львов», «Шамбон-ля-Форет», «Одесса», «Сурларли», «Коимбра». Показано, что существует три типа вековых колебаний, связанных с внешними источниками. Короткопериодные колебания (около 2 лет) и колебания средней периодичности (около 11 лет) хорошо известны. Предположено наличие долговременной модуляции вековых колебаний с периодом 80 лет, которая происходит в связи с изменениями солнечной активности. Зроблено спробу розділення вікових коливань, утворюваних зовнішніми джерелами, за даними обсерваторій «Нурміярві», «Лервік», «Ленінград», «Німек», «Бєльськ», «Хартланд», «Київ», «Львів», «Шамбон-ля-Форет», «Одеса», «Сурларлі», «Коімбра». Показно, що існує три типи вікових коливань, пов’язаних із зовнішніми джерелами. Короткоперіодні коливання (близько 2 років) і коливання середньої періодичності (близько 11 років) добре відомі. Припущено наявність довгочасної модуляції вікових коливань з періодом 80 років, яка відбувається через змінення сонячної активності. 2011 Article Secular variations of the geomagnetic field and solar activity / Yu. Sumaruk, J. Reda // Геофизический журнал. — 2011. — Т. 33, № 4. — С. 134-141. — Бібліогр.: 8 назв. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/97101 550.383 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України
institution	Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection	DSpace DC
language	English
topic	Научные сообщения Научные сообщения
spellingShingle	Научные сообщения Научные сообщения Sumaruk, Yu. Reda, J. Secular variations of the geomagnetic field and solar activity Геофизический журнал
description	Сделана попытка разделения вековых колебаний, создаваемых внешними источниками, по данным обсерваторий «Нурмиярви», «Лервик», «Ленинград», «Нимек», «Бельск», «Хартланд», «Киев», «Львов», «Шамбон-ля-Форет», «Одесса», «Сурларли», «Коимбра». Показано, что существует три типа вековых колебаний, связанных с внешними источниками. Короткопериодные колебания (около 2 лет) и колебания средней периодичности (около 11 лет) хорошо известны. Предположено наличие долговременной модуляции вековых колебаний с периодом 80 лет, которая происходит в связи с изменениями солнечной активности.
format	Article
author	Sumaruk, Yu. Reda, J.
author_facet	Sumaruk, Yu. Reda, J.
author_sort	Sumaruk, Yu.
title	Secular variations of the geomagnetic field and solar activity
title_short	Secular variations of the geomagnetic field and solar activity
title_full	Secular variations of the geomagnetic field and solar activity
title_fullStr	Secular variations of the geomagnetic field and solar activity
title_full_unstemmed	Secular variations of the geomagnetic field and solar activity
title_sort	secular variations of the geomagnetic field and solar activity
publisher	Інститут геофізики ім. С.I. Субботіна НАН України
publishDate	2011
topic_facet	Научные сообщения
url	http://dspace.nbuv.gov.ua/handle/123456789/97101
citation_txt	Secular variations of the geomagnetic field and solar activity / Yu. Sumaruk, J. Reda // Геофизический журнал. — 2011. — Т. 33, № 4. — С. 134-141. — Бібліогр.: 8 назв. — англ.
series	Геофизический журнал
work_keys_str_mv	AT sumarukyu secularvariationsofthegeomagneticfieldandsolaractivity AT redaj secularvariationsofthegeomagneticfieldandsolaractivity
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fulltext	Y. SUMARUK, J. REDA 134 Геофизический журнал № 4, Т. 33, 2011 НАУЧНЫЕ СООБЩЕНИЯ Introduction. The main field of the Earth has its origin in the core due to the currents running at a depth of about 2,900 km. The current system in the core is not stable and homogeneous. The main magnetic field at any point of the Earth’s surface changes over time. It has been recognized since the seventeenth century by Gellibrand. Now these changes are known as the secular variations (SV). Vector measurements of the field provide informa- tion about the direction of the field as well as its strength. Long time series of the mag- netic field elements at global network of magnetic observatories show also the space changes of the field. Usually the SV are computed from the differ- ence between two successive annual means and then are smoothed to at- tenuate the variations from external sources [Alexandrescu, 1996]. Beyond all doubts geomagnetic secular varia- tions consist of internal and external sources. Separation of these variations is a very difficult task so far as they vary with time and space and are het- erogeneous [Mandea, 2001]. To inves- tigate SV different methods are used: comparison of annual coefficients of the spherical-harmonic analysis of the geomagnetic field, comparison of the УДК 550.383 Secular variations of the geomagnetic field and solar activity © Y. Sumaruk1, J. Reda2, 2011 1Institute of Geophysics of National Academy of Sciences of Ukraine, Kiev, Ukraine 2Institute of Geophysics of Polish Academy of Sciences, Warsaw, Poland Received 7 February 2011 Presented by Editorial Board Member V. I. Starostenko Сделана попытка разделения вековых колебаний, создаваемых внешними источниками, по данным обсерваторий «Нурмиярви», «Лервик», «Ленинград», «Нимек», «Бельск», «Харт- ланд», «Киев», «Львов», «Шамбон-ля-Форет», «Одесса», «Сурларли», «Коимбра». Показано, что существует три типа вековых колебаний, связанных с внешними источниками. Корот- копериодные колебания (около 2 лет) и колебания средней периодичности (около 11 лет) хо- рошо известны. Предположено наличие долговременной модуляции вековых колебаний с периодом 80 лет, которая происходит в связи с изменениями солнечной активности. Зроблено спробу розділення вікових коливань, утворюваних зовнішніми джерелами, за даними обсерваторій «Нурміярві», «Лервік», «Ленінград», «Німек», «Бєльськ», «Хартланд», «Київ», «Львів», «Шамбон-ля-Форет», «Одеса», «Сурларлі», «Коімбра». Показно, що існує три типи вікових коливань, пов’язаних із зовнішніми джерелами. Короткоперіодні коливання (близько 2 років) і коливання середньої періодичності (близько 11 років) добре відомі. Припу- щено наявність довгочасної модуляції вікових коливань з періодом 80 років, яка відбувається через змінення сонячної активності. regular measurements of the field of magnetic ob- servatories and repeat stations. Experimental procedure. We have calculated SV(H) and SV(Z) as a difference between mean yearly values of horizontal (H) and vertical (Z) components on all (A), quiet (Q) and disturbed (D) days for magnetic observatories Belsk (BEL), Lviv (LVV), Leningrad (LNN) and only on all days for observatories Lerwick (LER), Hartland (HAD), Niemegk (NGK), Surlari (SUA), Odessa (ODE), Table 1 Observatory , grad , grad SV(H)0 Nurmijarvi 60,52 24,65 –3,59 Lerwick 60,13 358,82 7,79 Leningrad 59,95 30,70 –4,00 Moscow 55,48 37,32 –2,21 Niemegk 52,07 12,68 5,07 Belsk 51,83 20,80 1,29 Hartland 50,98 355,52 17,43 Kiev 50,72 30,30 –2,24 Lviv 49,90 23,75 0 Chambon la Foret 48,02 02,27 14,72 Odessa 46,78 30,88 –2,22 Surlari 44,68 26,25 –2,00 Coimbra 40,22 351,58 29,51 SECULAR VARIATIONS OF THE GEOMAGNETIC FIELD AND SOLAR ACTIVITY Геофизический журнал № 4, Т. 33, 2011 135 Coimbra (COI), Nurmijarvi (NUR), Kiev (KIV), Moscow (MOS) and Chambon la Foret (CLF). Geographic coordinates of the observatories are shown in table 1. The yearly mean values we ob- tained from WDC in Moscow [Golovkov et. al., 1983] and Kyoto [http://wdc.kugi.kyoto-u.ac.jp]. It is known that during magnetic storms mag- netospheric ring current develops. Due to the current, H-component decreases at low latitudes (Dst-variation). The decrease of H is maximal at equator and equal to zero at the earth’s poles. Thus, during high solar activity, the number of geomagnetic storms increases and mean yearly values of H-component are low. Dst-variation is observed in Z-component also [Sumaruk et al., 1980]. Due to the ring current, Z component varia- tions increase. Effect intensifies to high latitudes. Different ionospheric current systems such as au- roral electrojet, probably, also put in to the change of SV. Results and interpretation. Fig. 1 shows SV of H (a) and Z (b) — components at magnetic obser- vatory Lviv (LVV) from 1958 till 2000 for all (black), quiet (green) and disturbed (red) days. Fig. 2 and Fig. 3 show the same at magnetic observatories Belsk (BEL) and Leningrad (LNN) corresponding- ly. We see short (about two year) period variations and long period ones exist. Amplitudes of short period variations increase from LNN to LVV and are the greatest for disturbed days. Long period SV(H) appear to be in accord with quasi-sinusoi- dal law similarly to aa index changes reported by [Strestik, 1991] and Kp-index [Sumaruk Yu.,2001; Sumaruk P., 2001]. Fig. 1. SV(H) — (a) and SV(Z) — (b) — at magnetic observatory Lviv. Fig. 2. SV(H) — (a) and SV(Z) — (b) — components at magnetic observatory Belsk. Fig. 3. SV(H) — (a) and SV(Z) — (b) — components at magnetic observatory Leningrad. Y. SUMARUK, J. REDA 136 Геофизический журнал № 4, Т. 33, 2011 Fig. 4. SV(H) and SV(Z) variations for magnetic observatories LNN (a) and COI (b) from 1870 till 2000. Short and long periods SV(Z) variations coin- cide wonderfully in phase at the observatories. Un- fortunately we can not observe increase of SV(Z) amplitude from LVV to LNN, probably, because the latitudes of the observatories change only by about 10 degrees. Amplitudes of SV(Z) are also greater for D-days than for Q-days. Phenomenon is better observed for LVV and, maybe, it is con- nected with influence of induced current in un- derlying surface. Comparison shows that SV(H) and SV(Z) change is opposite in phase. It proves that short period variations have external sources. Fig. 4 shows SV(H) (circle) and SV(Z) (square) variations for magnetic observatories LNN (a) and COI (b) from 1870 till 2000. We observe the coincidence in time of short period variations as SV(H) and so SV(Z), but the variations at COI have greater amplitude. As to SV(H), it is understood so far as COI placed nearer to equator than LNN, but the increase of the amplitude of short period variations SV(Z) at COI may the most probably be explained by influence of induced currents. It is necessary to note that during the war years the observatories data at LNN and COI were un- stable. The most prominent fact is the coincidence in phase of the long period (about 80 years) varia- tions at both observatories, but SV(H) is shifted up and SV(Z) down on ordinate axis at COI rela- tively to LNN. It was shown earlier [Sumaruk Yu., 2001] that the changes of SV(H) at all middle and subauroral magnetic observatories of the north hemisphere of the Earth coincide in phase, but their amplitudes and positions relatively the ordi- nate axis are different. Dependence of SV(H)i at i-observatory on SV(H)i+1 observatory is SV(H)i=K×SV(H)i+1+SV(H)0, where K — is constant value for certain observa- tory and SV(H)0 is positive or negative number, also constant for this observatory, but it is chosen in such a way so that years of changes of SV(H) sign for all observatories coincide. For the most middle latitude European observatories these years are 1900—1903 and 1977—1980 . It is ne- cessary to note that during those years the jerks in the SV of magnetic declination were observed [Mandea, 2001]. Fig. 5 shows the dependence of the changes of SV(H)-variations (∆SV(H)) on the changes of mean year magnetic activity index ∆∑(H-Sq) for SECULAR VARIATIONS OF THE GEOMAGNETIC FIELD AND SOLAR ACTIVITY Геофизический журнал № 4, Т. 33, 2011 137 magnetic observatories BEL (b) and LVV (a). Cor- relation is low, but decreasing tendency of ∆SV(H) with increasing ∆∑(H-Sq) is observed very well. To investigate long period variations, we have chosen observatories LNN and COI which have long row of observations. Fig. 6 and Fig. 7 show dependence of SV(H) at BEL on SV(H) at LVV (a, b), SV(H) at KIV on SV(H) at LVV (c, d) SV(H) at SUA on SV(H) at LVV(e, f) and so on. The observatories names and time intervals are shown upwards of ordinate axis. The straight lines show linear regression equa- tions between values. These equations are shown in table 2. Points of crossing these lines and or- dinate axis show SV(H)0 values. As one can see the values and signs of SV(H)0 are different for observatories. If the reference observatory is LVV, SV(H)0=29,51 nT for COI and SV(H)0=17,43 nT for HAD. To verify these results, Fig. 8 shows de- pendence of SV(H) at HAD on SV(H) at COI from 1867 till 1999. Straight line shows linear regression equation between values. One can see that SV(H)0 is about — 12,33 nT, when reference observatory is COI, that may say that SV(H)0 is equal to SV(H)0 at COI minus SV(H)0 at HAD. Correlation between SV(H) becomes worse as distance between observatories increases. As it was shown in [Sumaruk T., Sumaruk Yu., 2007] at the regions where SV(H)0 are equal to zero the intense tectonic activity is observed. Except short period Table 2 Observatory SV(H)LVV Odessa =0,80SV(H)ODE–2,22 Leningrad =0,97SV(H)LNN–4,00 Kiev =0,82SV(H)KIV–2,25 Moscow =0,78SV(H)MOS–2,21 Surlari =0,94SV(H)SUA–2,01 Nurmijarvi =1,03SV(H)NUR–3,59 Belsk =0,83SV(H)BEL+1,29 Niemegk =0,91SV(H)NGK+5,07 Chambon la Foret =0,93SV(H)CLF+14,73 Lerwick =0,98SV(H)LER+7,80 Hartland =1,02SV(H)HAD+17,43 Coimbra =0,97SV(H)COI+29,51 Fig. 5. The dependence of the ∆SV(H) on the ∆∑(H-Sq) for magnetic observatories LVV (a) and BEL (b). Y. SUMARUK, J. REDA 138 Геофизический журнал № 4, Т. 33, 2011 Fig. 6. Dependence of SV(H) at different observatories on SV(H) at LVV. (about two years) and long period (about 80 years) about eleven year period variations are observed. Fig. 9 shows SV(H) variations at HAD (a) and LNN (b) observatories but short period variations are excluded by trapezium method. It is clearly seen that at the upper part of the solar cycles SV(H) decreases and at fall stage of solar cycles SV(H) increases. To exclude these variations mean per solar cycle SV(H) have been calculated. Fig. 10 shows dependence of mean per solar cycles SV(H) at HAD on the values of mean per solar cycles Wolf’s number from 15-th to 22-nd cycles. It is easy to see the rectilinear dependence between the values. Only 20-th cycle doesn’t fol- low the dependence. We may note that quasi- sinusoidal variations have also external source. Conclusions. SV-variations have external and internal sources. To separate internal source com- ponent it is necessary to exclude short period (about two years), middle period (about 11 years) and long period (about 80 years) variations. Am- plitudes of short period variations increase with growing of solar activity and are greater for D- days than for Q-days. Short periods SV(H) and SV(Z) change in opposite phases. Anti-correlation between SV(H) and magnetic activity is observed. Amplitude of the short period SV(H) variations decreases with increasing of the magnetic obser- vatories latitudes. That is to say short period SV(H) and SV(Z) are generated by external currents. Middle period (about 11 years) SV also depend on solar activity. Values of SV(H) decrease at the SECULAR VARIATIONS OF THE GEOMAGNETIC FIELD AND SOLAR ACTIVITY Геофизический журнал № 4, Т. 33, 2011 139 Fig. 7. Dependence of SV(H) at different observatories on SV(H) at LVV. Fig. 8. Dependence of SV(H) at HAD on SV(H) at COI for 1867 till 1999. upper phase of solar cycles and they increase at fall phase. To exclude SV dependence on the cycle solar activity the mean per cycle values are necessary to be calculated. After excluding short Y. SUMARUK, J. REDA 140 Геофизический журнал № 4, Т. 33, 2011 Fig. 9. SV(H) variations at HAD (a), LNN (b) with out shot period variation and Wolf number (c). Fig. 10. Dependence of SV(H) at HAD on mean per solar cycles Wolf’s number. and middle period SV variations, long period quasi-sinusoidal SV(H) and SV(Z) variation are observed. The period of the variations is about 80 years. It may be supposed that quasi-sinusoidal SV-variations are also connected with solar acti- vity. Mean per solar cycle values of SV(H) and the same Wolf numbers for fifteenth to twenty second cycles are highly correlated. Thus three types of SV(H) and SV(Z) due to external sources have been observed. SECULAR VARIATIONS OF THE GEOMAGNETIC FIELD AND SOLAR ACTIVITY Геофизический журнал № 4, Т. 33, 2011 141 References Alexandrescu M. Geomagnetic field direction in Paris since the mid-XVIth centure // Phys. Earth Planet. Inter. — 1996. — 98, — P. 321—360. Golovkov V. P., Kolomijtseva G. I., Konyashchenko L. P., Semyonova G. M. The summary of the annual mean values of magnetic elements at World magnetic observatories // IZMIRAN. — Iss. XVI. — 1983. — 342 p. Mandea M. How well is main-field secular variations known? // Contributions to Geophysics and Geo- desy. — 2001. — 31, № 1. — P. 233—243. Strestik J. Long term variations in geomagnetic and solar activities and secular variations of the geomagnetic field component // Studia geoph. ed geod. — 1991. — 35. — P. 1—6. Sumaruk P. Secular variations of the Earth’s magnetic field and their long term modulation // Contribu- tions to Geophysics and Geodesy. — 2001. — 31, № 1. — P. 355—356. Sumaruk Yu. On external sources of secular variations of the Earth’s magnetic field // Contribution to Geophysics and Geodesy. — 2001. — 31, № 1, — P. 353—354. Sumaruk T., Sumaruk Yu. On separation of the secu- lar variation of different origins // Publ. Institute of Geophysics, Pol. Acad. Sci. — 2007. — C-99(398). — P. 252—259. Sumaruk P., Feldstein Ya., Porchkhidze Ts. Geomagnetic field variations at Earth’s poles // Physica solariter- restris. — 1980. — № 12. — P. 70—78.

Secular variations of the geomagnetic field and solar activity

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