Secular and long-periodic oscillations of the solar activity

Vl.Ttasin Astronomy, Vol. 31, pp.

85--90,

0083-6656/88 $0.00+ .50 Copyright © 1988 Science Press & Pergamon Journals Ltd.

1988

S E C U L A R AND L O N G - P E R I O D I C O S C I L L A T I O N S OF THE S O L A R A C T I V I T Y

Ussuriisk

V. F. C h i s t y a k o v Solar Service Station,

USSR

So called "ll-year" cycles have variable period and amplitude. Fig.

~n

1 is shown the time series of the parameter W M - Wolf's number

at maxima of such cycles. We can see the secular oscillations of W M values. They have two maxima. There are two kinds of secular cycle: long and short. They alternate one after the other. Long cycles have a duration of nearly

I15 years, and short cycles, 95 years.

The rising branch of the long cycle is gently sloping, while the falling branch is steep. The structure of the short cycle is opposite to the structure of the long cycle. The author has tested the reality of such a scheme using data for the last 2000 years. This period was divided into 95- and 115year parts. The beginning epoch was minimum of the solar activity.

1810, i.e. the epoch of the deep

Fig.2 shows the summary histograms of

the sunspot numbers, which are seen with the naked eye, divided into 9~and

ll5-year time intervals. This picture exhibits data of the

chronological

records made mainly in China and Korea. The total

number of such records is 326. It may be believed that the full cycle of the long-periodic oscillations of the solar activity equals 210 years: 95 + 115. Some scientists

found early on almost 200 years periodicity

aurora, radiocarbon and

18-oxygen variations

in

in three rings. Oscil-

lations of the varve thickness of the ancient lake Elatina in Australia also coincided with the scheme of 210 year cycles. According to Williams

(1981) that lake was in the Precambrian 680 millions

years ago. The Elatina varve show haps,

12-year periodicity, which, per-

is connected with solar activity.

work it may be concluded

On the grounds of Williams

that the short secular cycle had a dura-

tion of 138 years, and the long secular cycle - 158 years. The sum of such cycles equals 296 years. It is possible that the rhythm of 85

86

V.F.

Chistyakov

the solar activity now is higher than 700 million years ago. The 300 year cycles in the Precembrian may correspond to the recent 210 yeal cycles. The amplitude of the II year cycles anticorrelate with its duration. In Fig. 3, we can see the variations of parameters T 5 - the moving average of the sunspot periods and WM5 - the moving average of the Wolf's number at maxima for the 5 following cycles. Here there are secul~r and more long-period oscillations. One interesting fact may be remarked upon. The lamina of the Elatina lake have negative correlation between the average thickness of the lamina and the average durations of the "]2-year" cycles. We can use the anticorrelation of T and W M for research on the solar activity pecularities rows: auroras,

in the past on the base of some natural

tree rings, a varve etc. In present work I use for

this purpose two rows: ]) the thickness of the annual rings of an American sequoia according to A. E. Douglass (]919), and 2) the thickness of the annual silt layers of Saki lake (Crimea) according to W. B. Schostakowitsch

(]93]).

Both these rows are non periodic and the solar information here is very sparse. The author has used new methods for searching for solar periods in these rows. The time row of the sequoia rings include the period from ]310 B.C. to 1914 A.D.

(nearly 2,200 years). At first I calculate the 23

year moving average of the values such row. Then the time-frequency spectra are calculated for the 300-year periods with

I00 year steps.

In total 29 power spectra are obtained. Fig. 4 shows the power spectrum curve for the period

]60]-1900

A.D. We can see that the peaks of a solar nature (periods of |] and 22 years) are not distinguished. It is known that the sunspot period changed from 7 to 17 years. Therefore I calculated the weighted value T with periods from 3.5 to 8.5 years; then the value T was doubled: t

II

=2T

The parameter tll has global climatic or heliophysical

significance.

Oscillations of the Solar Activity The time variations of curve

tll

87

for different trees are shown on Fig. 5.

1 - for the sequoia (I|00 - ]900 A.D.),

curve 2 - for the Flagstaff pines (1400 - 1900 A.D.), curve 3 - for the Turkestanic

juniper (1200 - 1900 A.D.),

curve 4 - for the Japanese cypress (]200 - ]900 A.D.). The time course of tll for the sequoia in the last 3000 years is shown on Fig. 6. Also shown here are: the radiocarbon A14C curve according to suess (1980) and the curve of the Caspian Sea level H MThe radiocarbon variations

~14C show the oscillations of the solar

activity. The Caspian Sea level curve shows the climatic change (so far the HM variations are opposite to the world ocean leve'l). Consequently,

it follows from the Fig. 6, climatic changes are

connected with the solar activity oscillations.

Such a conclusion

coincided with that of Bray (1968). Periods of low solar activity were during (the SpSrer and Maunder minima) and at nearly

15th to 17th centuries I000 B.C. The duration

of the sunspot cycles was nearly equal to ]3 years at that time. Next the h series - the thickness of the annual silt layers of the Saki lake was researched.

The length of the h series was nearly

4,200 years (from 2276 B.C. to ]897 A.D.). The power spectra are calculated for the 300-year intervals which changed to the 100-year steps. All together there are 40 such spectra. Here the solar peak (period nearly

11 years)

is very difficult to distingu'ish.

The next method will be used for discovering solar peaks. It is known

that there is a peak-satellite

(the period of n~arly

in the power spectrum of the Wolf numbers

]0 years)

in the vicinity of the l]-

year peaks• The peak-satellite has an almost constant period and therefore we can use it as a reference

to search for solar peaks with

variable period - t

11" The time course of t]] for the last 4,200 years is in the Fig.

7 • Here also the radiocarbon curve

AI4 C is shown. According to AI4 C

curve the "l]-year" cycles had very long durations at the following epochs:

1200-800 B.C.

(tl] = ]].9 - 11.5 years) aL1d nearly

]550 A.D.

(tll = 11.8 years). Very low solar activity also occured at those epochs. The climatic data show that the little following epochs: 3500 B.C.,

1000 B.C. and

ice ages are at the

]500 A.D. They repeat

88

V.F.

Chistyakov

themselves through 2500 years. The little ice ages coincided with the periods of the deep depression in the solar activity. In these epochs the sunspot cycles are very long. It is necessary to notice that Suess (]980) discovered a period of 2,400 years from the radiocarbon variations. Bray (]968) first showed the connection between the solar activity and the little ice ages. The present work agrees with his conclusions. The last little ice age come "to an end in the 19th century. The average duration of the sunspot cycles in the 20th century was equal to ]0.7 years. Therefore the solar activity in the 20th century is at the normal high level or nearly so. Kopecky (1980) and Chistyakov (198]) forecast the very high level of solar activity in next century. The present work confirms such a conclusion. Oeneraly it may be expected that the solar activity level will be very high during the next 2,000 years.

REFERENCES

Bray, J. R., (1968), Nature, 220, 672. Chistyakov, V. F., (1981) Solnechnye dann~e, 9, 107. Douglass, A. E., (1919) Climatic cycles and tree-growth, (Washington) p.127. Kopecky, M., (1980) Bull. Astron. Inst. Czechoslovakia, 31, I. Schostakowitsch, W. B., (1931) Gerlands Beitra~e zur Geophysik, 30, 281, Suess, H. E., (1980) Radiocarbon, 22, 200. Williams, G. E., (1986) Scientific American, No. iO, p.62.

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