Boris Komitov /selected abstracts of papers
and presentations (1997-2011)


Boris Komitov

On the basis of indirect data for 3rd - 20th century - obtained over
the base of evaluations on the nine degree power scale of 11- year Schove`s
series cycles, time variations of solar activity has been investigated for
the above mantioned period of time. As a result
104 and 204 - year cycles of duration, as well as traces of cyclic
variations of 77,88,130 and 350 period of years have been established.A
comparison with the data of radiocarbon contents in ligneous sample has been
made, and it is evident that the main distinguishing feature,between
Schove`s series and C14 temporary time series,is the absence of
trend and cycles of duration of over 500 years in the data of the first sample
and their presence in the second one.The validity of the relationship
W2 W1, has been checked,where W1 and W2 are respectively near maximum
Wolf`'s number values for the even and the odd cycles following them,
concerning the investigated period of time i.e.1700 years.On the
grounds of the aforesaid the probability for the breach of order in that inequality
i.e. the even cycles to be higher than the odd cycles following them, increasis
at high even cycles. The breach of order is a practically inevitable event
at the highest even cycles for which near maximum average annual Wolf 's
number values exceed 125 . On the basis of these results an assumtion
has been made that the forthcoming 23rd solar cycle will be weaker in power
than cycle No 22.

in BULG. GEOPHYS. JOURNAL 1997 v 23 No 1-2
See also /in Bulgarian/ The Violation of Gnevishev -Ohl Rule...) and the next abstract


Boris Komitov
Institute of Astronomy, Bulgarian Academy of
Sciences, P.O. Box 179, 6000 Stara Zagora, Bulgaria;
Boncho Bonev
Ritter Astrophysical Research Center, Department of
Physics and Astronomy, University of Toledo,
Toledo, OH 43606;
Received 2000 August 29; accepted 2001 April 26;
published 2001 May 30

We examined the conditions for violations of the Gnevyshev-Ohl rule,
which states that the even-numbered
11 yr solar cycles have been followed by higher in amplitude odd-numbered
ones.This regularity has been valid for the last 150 years, but it is very
likely to be broken in the current 11 yr cycle 23. We used the Schove
series, which includes the main macrocharacteristics of the 11 yr cycles and
is continuous since the end of the third century. The reliability of these
data has been discussed. A total of 152 cycles were investigated,
the last onebeing cycle 21 in the International Sunspot Number series.
We showed that there is a well-outlined group of even-numbered 11 yr cycles
that are very likely to be followed by weaker odd-numbered ones. These are
the most powerful even cycles, characterized by maximum
monthly smoothed Wolf numbers exceeding 125 and decay times of 6 yr or
more. The main factor for violations of the Gnevyshev-Ohl rule is a very
high maximum of the even-numbered 11 yr cycle. Applied to the present
Hale cycle, which consists of 11 yr cycles 22 and
23, our analysis implies a high probability for violation of the Gnevyshev-Ohl
rule. The development of 11 yr cycle 23 confirms this conclusion. We
argue that the present 11 yr cycle should not be qualified as “abnormal”
when referring to the fact that it breaks a regularity that has lasted for
150 yr. The 11 yr cycle 23 might reveal a feature in the dynamics of the Hale cycle
that the strongest even-numbered 11 yr cycles are likely to be followed by
lower amplitude odd-numbered ones. We briefly discuss the relation
between the long-term solar variability and the current violation of the
Gnevyshev-Ohl rule

. The Astrophysical Journal, 554:L000–L000, 2001 June 10

See also
Solar Activity Prediction Service


Bonev, B.; Komitov, B.

AA(Bowling Green St. Univ./Univ. of Toledo),
AB(Inst. of Astronomy - Bulgarian Academy of Sciences)

We provide new two-variable fits describing the variability of the Haser
scale lengths of CN and its parent molecules. As in our previous reports
on this subject we use the heliocentric distance and the 10.7-cm solar
radio flux as independent variables. Such description reduces the error
bars and avoids the systematic behavior observed in the residuals of the
one-variable fits with only the heliocentric distance. The data for the
CN parent scale length include 56 reported values from different comets
over a period of two solar cycles. On that basis, using the connection
between true and Haser scale lengths, we discuss the possible CN parents
HCN and C2N2. These two molecules have been separately highlighted in
different papers as the most probable candidates for a major CN parent.
Our two-variable fit implies a brightness distribution of CN which may
be explained under the assumption that the C2N2 molecule is the single
CN parent.

Journal: American Astronomical Society, DPS
meeting #32, #41.05Publication
Date: 10/2000
Origin:AASAbstract Copyright
: (c) 2000: American Astronomical
Society Bibliographic Code:


Komitov, B.; Bonev, B.; Bonev, T.; Ivanova, A.
AA(Inst. of Astronomy - Bulgarian Academy of Sciences)
AB(Univ. of Toledo)
AD(Inst. of Astronomy - Bulgarian Academy of Sciences)

CCD observations on comet C/1999 S4 (LINEAR) were done on July 3 and
July 4, 2000 with the 2-meter telescope in the National Astronomical
Observatory "Rozhen", Bulgaria. We used a narrow-band filter centered at
387 nm. Brightness profiles of CN, which correspond to conditions close
to the current solar maximum, were obtained and analyzed with the Haser
and the vectorial exospheric models. The results are compared with obtained for
other comets.

Journal of American Astronomical Society, DPS meeting #33,
#41.21Publication Date:10/2000
Origin:AASAbstract Copyright:
(c) 2000: American Astronomical
SocietyBibliographic Code:


Boris Komitov

The subject of this report is to demonstrate the changes in the power
appearences of the centural and bicenturial solar cycles .
For this purpose two independent series indirect data on the base
of the solar actuvity have been used i.e. :1) Schove's series ,
containing continuous data for the last 1700 years . 2) radiocarbon
tree series for the last 4500 years. Cyclic changes at the amplitudes of the
two cycles have been established .The amplitude variations are
very big at the bicentural cycle ( T = 205 yrs. ). As a result , about 2300
- year powerful cycle of duration , has been established among them
and also a second one of about 1050 period of years which
is weaker than the first one . In this context, around the deep
minimums of the supercentural solar activity course , as for example
the period XV/ th - XVII/ th century ( between the Sprorer's
and Maunder's minimums ) the bicentural cycle completely dominates
over all the rest , which compete with its variations . In the epochs
which are removed , back or earlier in the time at about 1000 - 1200
years, compared with deep solar minimums the picture is
just the opposite . In connection with these facts the bicentural cycle
is very weak or is completely absent in this epochs . A very weak
dynamics showed also the powerful appearances of the centural cycle .
Their range of varability has an average period of about 1350 years.

paper in 6th National Conferrence of Solar-Terrestrial Physics,Sofia,1999


Boris Komitov

The purpose of this study is to concider the important role of 2200 - 2400
year solar - climatic cycle on the historical process.The so obtained
conclusions here , confirm " The theory of civillization " by Arnold
Toynbee from the base of a new point of vew.

in Proceedings of Scientific Conference with international participation
"Stara Zagora 2002", Stara Zagora , June 6-7,2002, Part IV,pp 162-166


Boris Komitov and Vladimir Kaftan

The series of macrocharacteristics of the 11-year Schwabe–Wolf
cycles (the so-called Schowe series) has been used to specify notions
of the character of long-term variations in solar activity.
A mathematical statistic analysis of data in the series has been
performed using two independent methods. Statistically significant
cyclic oscillations with periods of about 100, 122, 205, 350 and
1200 years have been revealed. About 200-year cycle, which was
unnoticeable in the relatively short 250-year series of the most
reliable instrumental data (since it was reduced by other long-period
oscillations), proved to be the most powerful among these oscil-lations.
An analysis of obtained results has indicated that it is highly probable
that the next long-period minimum of solar activity, which will possibly
be not so deep as the Maunder and Sperer minimums, will be formed in the
21st century.

International Journal of Geomagnetism and Aeronomy,v.43,No5,2003,pp 553-561

The full HTML version of this paper is here


Boris Komitov, Boncho Bonev, Kaloyan Penev and Stephano Sello

in Proceedings IAUS 223 'Multi-Wavelength Investigations of the
Solar Activity', eds. A. V. Stepanov, E. E. Benevolenskaya &
A. G. Kosovichev, Cambridge University Press, pp.705-706

Click here



Boris Komitov


In this paper an comparison between the solar activity variations and climate changes has been provided. The used solar activity reconstructions are on the base of almost all main, famous nowadays data series: a) instrumental observations of sunspot activity during the last ~ 400 years; b) ground based and satellite observations of solar EUV , radio and corpuscular fluxes , solar and interplanetary magnetic field, solar wind and total solar irradiance for the last few decades; c) historical records for auroras and simple eye observations of sunspots (for the last 1700 years); d) “cosmogenic” radioisothopes ( 14C and 10Be) measurements in tree rings (for the last 10 000 years), continental ices ( the last 1200 years) and oceanic sediments probes (the last ~400 000 years) .

Four time-scales of the climate changes has been used in this study: “geological” - for the last ~ 800 million years; “prehistorical “ (1 and 2)- for the last ~130 000 years and ~23000 years respectively ; and “historical” scale – for the last 1200 years. For the last three one the relationship ‘Sun-climate’ has been discussed. The climatic changes in Bulgaria during the last century and its relation to the solar activity has been to shortly described.

It is concluded that the Sun’s variability is the main factor of the climatic changes during the last ~ 400 000 years . The Earth orbit’s effects, described in Milankovich theory are significant too in “prehistorical scale-1”, but most probably, they are on the second place. All significant climatic extremums during the last 10 000 years are in coincidience with corresponding solar activity extremums. The “global warming” effect in 20th century corresponded with the most higher solar activity level during the last ~ 1000 years, and no antropogenic effect for the explanation of this climatic phenomena is necessary to include .

An evidence that the main historical tendencies are modulated by climatic changes and solar-climatic relationships is given. The last one is discussed in the light of Arnold Toynbee’s “civillization theory”.


( a paper printed in Nauka, 2005,No6) in Bulgarian

The full version of this paper in English is here


Boris Komitov

The main aim of this study is to find different observational characteristics of sunspot cycles, which could be used as precursors of forthcoming supercenturial solar minima. A data set of indirect records for solar activity (so called Schove’s series) between 214 BC - AD 2000 has been analyzed. Two potential precursors of the further behaviour of the solar activity have been pointed out – the violation of  Gnevyshev-Ohl’s rule in even-odd numbered pairs of  Schwabe-Wolf’s cycles and the temporary increasing of the cycles duration. A third method for prediction, based on two-factor regression model has been applied too. In this method the magnitudes of both even-odd sunspot cycles are used as predictors. On the base of the actual data for the current pair of the Zurich cycles No. 22 and 23 a prediction for a relatively weak sunspot cycle No. 24 with expected maximum about AD 2013 and Wolf’s index Wmax ~ 90 was made. A prediction of forthcoming supercenturial solar minimum in the period AD 2030–2080, like  the Dalton minimum in AD 1795-1830, is given also. Some climatic effects may be expected in the period of the supercenturial solar minimum. As a result a  “global cooling” climatic effect in the range of 0.4- 07 C could be expected.

Bulg.Astron.Journal., 2007,No 9

The full version of this paper in English is here

Boris Komitov

This is the first one of  a three papers series, which concern the problem for the powerful subcenturial and quasi-centurial  (mainly 50-55 , 60-65 and ~120-130 yrs)  climatic oscilations origin. The 50-55 and 60-65 yrs cycles  are  very clearly detectable in a large number of  global as well as regional climatic and climate –related  parameters such as the Northern hemisphere and World Ocean surface temperatures, regional temperatures and  tree rings width series, atmospheric CO2 density etc.  The abovesaided cycles havn’t   clear analogs in sunspot  activity.
    A detailed study over diffrerent types of  solar, geophysical and climatic indexes (the Zurich (Ri) and Group Sunspot Numbers (GSN),  the “Greenland” and “Antarctic” 10Be , the middle latitude auroras  + two global and  one regional climatic time series)  has been provided. An  evidence that the subcenturial climatic oscilations in range of 30-70 years (and inddeed the 120-130 yrs cycle too) are caused  by processes on the Sun (most probably in the corona ) has been found as a final result (paper III).
    The subcenturial  quasi-cyclic oscilations in Earth surface temperatures as well as the “cosmogenic” berryllium time series  from Greenland ( AD 1423-1985) and Antarctica ( AD 850 – 1900) ice probes are the object of  the present papers.  A 60-67 year cycle has been found in the both to ones. It is very powerful in the “greenland” 10Be series  and relatively weaker, but statistical significant in the “antarctic” one too. A good coincidience between the extremums of  10Be and climatic indexes has been found. On other hand there are weak statisticaly significant peaks near to ~60 years both in Ri and GSN series too.  The intermediate conclusion in this paper (I) is that the sunspot and climatic data are not enough strong basis to choice is the quasi 50-55 ,–60-65 year and 120-130 yrs 10Be cycles by solar or climatic origin. In the case if  a solar source of 10Be (and climate) subcenturial oscilations exist it should not be in strong relationship with the overall sunspot activity indexes such as Ri and GSN. Most probably this source could be “based”  in the corona.

Bulg.Astron.Journal., 2009,No 11

The full version of this paper in English is here



Boris Komitov

It has been already pointed out in the our previous paper I  that the subcenturial climate cycles  by durations in the range of  50- 70 years could be by solar origin.  As an argument for the last  one the fact for the existence of  weak , but statistically  significant   cycles traces of subcenturial range in the sunspot  Zurich and Group sunspot number series has been noted.
Additional evidences for the solar origin of the subcenturial climate variations in this paper (II) are suggested.   Two indirect  and independent  each other solar proxies has been studeid: A. The “cosmogenic” 10Be data series (the both “Greenland” and “Antarctic” ones) ;     B. The middle latitude aurora (MLA) events for 18th and 19th centuries from a catalogue data which are published  in  the National Geophysical Data Center of USA.
The most  important results could be summarized as: 1. There are strong quasi-50-55 ~65  and ~ 120 year oscilations in the “Greenlad” 10Be concentration data series. 2. A relaatively weak , but stattistical significant ~60-65 year cycle  +  essentially powerest 130 year cycle in the “Antarcic” 10Be series   has been found too. 3.  There is very strong  62-63 year oscilation in the annual numbers of middle latitude aurora.  The last fact is a very strong evidence that a cycle with the corresponding duration exist in the most powerful solar activity phenomena ( flares and CME’s).
There is a relative good coincidience berween the corresponding extremums of 60-yr cycles in 10Be and MLA series.  The last one is an  indicator that most probably in the epochs of  60 yr maximums of MLA a significant part of 10Be is generated in the stratosphere by high energetic solar particles  in addition to the galactic cosmic rays (GCR) .

Bulg.Astron.Journal., 2009,No 12

The full version of this paper in English is here

Ivan T. Ivanov(1), Valentina T. Taneva(2) and Boris Komitov(3)

(1) Department of Physics and Biophysics, Medical Institute, Thracian University, 6000 Stara Zagora;

(2) Institute of Applied Physics, Technical University of Sofia

(3) Bulgarian Academy of  Sciences - Institute of Astronomy, 6003, Stara Zagora-3, P.O. Box 39

The visible diameter of Sun oscilates with a period of 160 min. The same type of periodicity is also found in a huge number of solar radiation parameters. To elucidate the origin of these longitudinal radial pulsations we have used the equation for the equilibrium of inner layers which, after linearization, turned into the harmonic oscilator equation. The latter equation allows radial pulsations whose period and wave length were calculated using regresion expresions for the gas presure and density in various layers. The radial pulsations originate at the surface of active zone and propagate til the litosphere, where they undergo full inner reflection producing undersurface stationary waves with a period of  150-160  min.

 Key words: Sun; 160 min radial pulsations; mechanical waves; balance equation

e-print: arXiv:0912.1211

The full version of this paper in English is here

The "Sun–climate" relationship. III. Solar eruptions, north-south
sunspot area asymmetry and Earth climate

Boris Komitov
Institute of Astronomy, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
(Research report. Accepted on 12.12.2009)

Abstract. In this Paper III, the last one of the series, additional evidences are given that
the fluxes of solar high energy particles, with energies higher than 100 MeV (the solar
cosmic rays), are a very important component of the “Sun–climate" relationship (see also
Paper I and Psper II). It is known that the total solar irradiance and the galactic cosmic
rays produce an integral climate effect of cooling in sunspot minima epochs and warming in
sunspot maxima epochs. Contrariwise, the powerful solar corpuscular events cause cooling
predominantly during the epochs of their high levels. By this reason subcenturial global
and regional temperature quasi-cyclic changes with duration of approximately 60 years
could be tracked during the last 150 years of instrumental climate observations. This paper
shows that this subcenturial oscillation is very important in the group sunspot number data
series since the Maunder minimum up to the end of 20th century. Only a relatively short
period, closely before and during the last centurial Gleissberg-Gnevishev’s minimum (AD
1898-1923), when this cycle is totally absent, is an exception there. Thus the solar eruptive
activity make the total "Sun–climate" relationship essentially more complicated as it could
be expected if only the total solar irradiance and the galactic cosmic rays variations are
taken into account. From this point of view the climate warming tendency after AD 1975
has rather natural than anthropogenic origin. It is also shown that the efficiency of the solar
corpuscular activity over the climate strongly depends on the "north-south" asymmetry of
the solar activity centers (as a proxy the sunspots area north-south asymmetry index A
is used there). The climate cooling effect in the Northern hemisphere is most powerful
during the epochs of predominantly positive values of A. This effect is very significant in
combination with high level of the index of the group sunspot number. A strong quasi
120-130-year "hypercycle" has been detected in the A index during the period of AD 1821-
1994. Most probably the observed 120-130-year cyclity in the climate and cosmogenic 10Be
continental ice core data (both "Greenland" and "Antarctic" series) is related to this cycle.
In the end the expected climate changes during the next decades and especially the new
solar sunspot cycle No 24 are discussed on the base of the "multiple" nature of the "Sun–
climate" relationship.

Key words: Sun, sun-climate relationship, sunspots, sunspot asymmetry

The full version of this paper in English is here

About the use of a modified brightness parameter for photometric observations of comets

Boris Komitov, Vladimir Shkodrov
Institute of Astronomy, Bulgarian Academy of Sciences
72 Tsarigradsko Shousse Blvd., 1784 Sofia, Bulgaria
(Research report. Accepted on 09.02.2010)

Abstract. The aim of this paper is to study the mathematical features of a cometary

photometric parameter, which is called by us a "modified intensity". It is defined as ǫ(l) =
E(l)l, where E(l) is the intensity of a separated gas emission on a projective (pericentral)
distance l to the cometary nucleus. The Haser’s model of the parent and daughter gas
molecules distribution is used. It is pointed out that the parameter profile ǫ could be used
directly for a prompt analysis both of the main generation mechanism of the observed
emission s, as well as of a rough parent molecules scale length estimation in the range of
50% precision.

Key words: comets, cometary photometry, parent molecules

The full version of this paper in English is here

Determination of the sunspot minimum epoch between the cycles No 23
and 24 and prediction of
the cycle No 24 magnitude on the base of
"Waldmeier’s Rule"

Boris Komitov, Peter Duchlev, Konstantin Stoychev,
Momchil Dechev, Kostadinka Koleva
Institute of Astronomy and NAO, Bulgarian Academy of Sciences, Sofia

(Research report. Accepted on 29.09.2010)

Abstract. The main purpose of this study is determination of the solar minimum date
before the new sunspot cycle No 24. The purpose is realized by using of four types of mean
daily data values for the period Jan 1, 2006 – Dec 31, 2009: 1) the solar radioindex F10.7;
2) the International sunspot number Ri ; 3) the total solar irradiance index (TSI), and
4) the daily number of X-ray flares of classes from “B” to “X” by data of the soft X-ray
channel (0.1–0.8 nm) of the GOES satellite. It is found that the mean starting moment of
the upward solar activity tendency (the mean solar minimum) is Nov 6, 2008. So, the solar
cycle No 23 length is estimated to ~ 12.6 years. A conclusion for a relatively weak general
magnitude of solar cycle No 24 is made. Using a relationship based on the “Waldmeier’s
rule” a near maximal value of the mean yearly sunspot number of Ri = 72 ± 27 has been
determined for cycle No 24.

Key words: Sun, solar minimum, solar cycle No 24

The full version of this paper in English is here

Boris Komitov

Bulgarian Academy of Sciences- Institute of Astronomy and NAO Rozhen;


The dynamics of  solar electromagnetic flux during the downward phase of  sunspot cycle No 23 (SC23) and the
 upward phase of cycle No 24 (SC24) is analysed.  For this aim the instrumental data series of  TIM
(Total Irradiance Monitor) and SOLSTICE (The Solar Stellar Irradiance Comparison Experiment) instruments on
the board of SORCE satellite during the period March / May  2003 – February 2011 are used.  The study contain
analysis of variations of TSI, mid UV-range (180-310 nm) flux  and the “faculae” MgII –index.  A comparison  with
the sunspot and flare activity is made. The obtained results in the aspect of long term variations of solar activity,
 as well  as to the ozone and climate changes are discussed.

Bulgarian Astronomical Journal 2011 v.17.  pp110-117

The full version of this paper in English is here


Boris Komitov   and Konstantin Stoychev

Bulgarian Academy of Sciences – Institute of Astronomy and National Astronomical Observatory “Rozhen”, Bulgaria, Sofia;


The aim of this study is to analyse the long-term (multiannual) variations of the total ozone content (TOC) on the base of TOMS instrument measurements on the board of Nimbus-7 satellite for the period 1979-1993 AD. The total effects of the solar activity forcing over stratosphere ozone has been investigated by using multiple regressional analysis. The monthly radio-index F10.7, the cosmic rays neutron flux, the geomagnetic index Ap and the number of GOES x-ray X-class flares have been used as solar or solar-modulated parameters as predictors in the model. The global mean-monthly TOC parameter has been used as a predictant.
     It has been found that the coefficient of correlation of the model between TOC and above-mentioned solar and geomagnetic factors is about 0.544. Thus the corresponding factor variance is about 37%. The results calculated by the model have been removed from the original TOC data. It has been found out that during the first 12 years since 1979 the downward trend is predominantly caused by the solar and solar-modulated processes. However during the remaining 3 years after 1990 the slope of the negative trend has been essentially increased. This phenomenon could only be explained by some catastrophic event. Most probably such one is the Pinatubo eruption in June 1991.  An evidence for the possibility that the last one is caused by trigger – effect from the extremally high solar flare activity in May-June 1991 is given.

Bulgarian Astronomical Journal 2011 v.17.  pp118-125

The full version of this paper in English is here

Boris Komitov, Nikolai Marinov


In this paper a first testing  series of radiobursts observations at f= 29.9 MHz during the period
April 2009- March 2011 in Stara Zagora, Bulgaria, as well as their analysis is discissed.  The main interest is focused over the observations on Feb. 15. 2011 –one of the most active days during  the upward phase of
solar cycle No 24.

Bulgarian Astronomical Journal 2011 v.17.  pp126-132

The full version of this paper in English is here


Boris Komitov

Abstract. The possible trigger mechanisms by solargeomagnetic origin for excitation of part of terrestrial tektonics events (earthquackes and volcanic erruptions) are subject of the present study. Evidences, that some of the most significant tektonic events during last decades are close correlated with solar eruptive processes and corresponding geomagnetic storms, are given. The most powerful eruption in 20th century of the Pinatubo volcano in 1991 as well as the catastrophic Japan’s earthquacke in 2011, March 11 are considrered as examples. A detailed analysis over the Pinatubo eruption, where the solar-geomagnetic trigger effect even in the separated phases of volcanic eruption is clear visible, has been provided. The possible physical mechanisms for generation of solar- geomagnetic trigger forcing over Earth tektonics are discussed too.

Keywords: Sol, Earth, tectonics, earthquakes, volkan.

Geosciences, 2011, No 2 (multimedia, in Russian)

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The long term solar activity regarding to 24th Zurich cycle

B.Komitov and V. Kaftan

 Abstract. In this paper an estimation of the present solar activity state on the base of time series analysis of different parameters is given. The longest presented there time series are data for auroras, naked eye visible sunspots, earthquakes, extremely meteorological events, annual tree ring widths, radioactive isotopes contents in tree rings, speleological objects, corals, continental ices, oceanic sediments etc. The main oscillations with periods close to 100, 200, 350 and 1100 years has been established in these series. The possibility of secondary long term solar activity minimum during the current century is demonstrated and proved. The last one is expected on the base of superposition of supercenturial oscillation components as well as due to amplitude modulation of ~200 yr cycle by the quasi- bimillenial (2200-2400 yr) solar Hallstadtzeit cycle. An substantiated suggestion about involvement of the current solar activity in the starting phase of a long periodic solar minimum, which deepest phase should be expected during the second half of the present century, is made. The moderate amplitudes of the previous and present solar cycles are also an indication for the beginning of long periodic solar activity decreasing.

 Keywords: Solar activity, solar minimum, solar cycle

Geosciences, 2011, No 3-4  (multimedia, in English)

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