Solar Cycles

Ionospheric total electron content (TEC) of the equatorial ionization anomaly (EIA) is studied by analyzing dual-frequency signals of the Global Position System (GPS) acquired from a network of receivers around the Asian-Australian region during 1996-2004. The latitude, occurrence time, strength of the most developed EIA crest, and crest-to-trough ratio (CTR) for both the noon and post-sunset sector obtained from a daily TEC contour map have been used to study the solar cycle variations of EIA in the Asian-Australian region. The results reveal that semiannual and seasonal variations were the dominant factor that controls the morphology of the EIA structure which can be identified in the past studies (e.g. . It is also found that the latitude and local time position of the anomaly crest show a hemispheric asymmetry because (a) The northern crest of EIA is expanded during the equinox indicating a weak semiannual variation while the southern crest is inhibited during June-August presenting a strong seasonal variation, and (b) The local time of the northern crest appears ∼1.3 h earlier than that of the southern crest in June while showing no difference at December. Solar activity dependence is more evident in the EIA crest region than in the EIA trough region and least in the post-sunset sector at equinox. A seasonal linear relationship is derived between the post-sunset CTR and solar flux, which should be caused by the solar-dependant equatorial E×B vertical drift.

Sunspots provide total solar irradiance (TSI) proxy records for the last 310 years. Speleothem achieves are still
only of TSI proxy record providers, which allow extending of the TSI experimental records back to the pre- instrumental
times. Therefore they are very important for the assessment of the solar forcing of the climate in the pre-industrial era.
Using such speleothem records we demonstrated that variations of the solar irradiation which can produce climatic
variations are: (i) powerful prolonged solar cycles, which affect climatic variations and (ii) amplification of solar
irradiance impact on climate by different potential non-linear mechanism or by a combination of them. Such
amplification is important at durations shorter than 11 years but can be more significant in timescales less than 1 year.

Ionospheric total electron content (TEC) of the equatorial ionization anomaly (EIA) is studied by analyzing dual-frequency signals of the Global Position System (GPS) acquired from a network of receivers around the Asian-Australian region during 1996-2004. The latitude, occurrence time, strength of the most developed EIA crest, and crest-to-trough ratio (CTR) for both the noon and post-sunset sector obtained from a daily TEC contour map have been used to study the solar cycle variations of EIA in the Asian-Australian region. The results reveal that semiannual and seasonal variations were the dominant factor that controls the morphology of the EIA structure which can be identified in the past studies (e.g. Wu et al., 2008). It is also found that the latitude and local time position of the anomaly crest show a hemispheric asymmetry because (a) The northern crest of EIA is expanded during the equinox indicating a weak semiannual variation while the southern crest is inhibited during June-August presenting a strong seasonal variation, and (b) The local time of the northern crest appears ~1.3 h earlier than that of the southern crest in June while showing no difference at December. Solar activity dependence is more evident in the EIA crest region than in the EIA trough region and least in the post-sunset sector at equinox. A seasonal linear relationship is derived between the post-sunset CTR and solar flux, which should be caused by the solar-dependant equatorial E×B vertical drift.

This paper presents the development of a model to predict solar cycle (SC) 24 using the technique of neural networks (NNs). The model is provided with the time input parameters defining the year and the month of a particular SC, in order to characterise the temporal behaviour of sunspots as observed in the last 10 SCs. Geomagnetic activity measured by the aa index is also introduced as an input to the NN model in such a way that the model establishes the relationship between the aa index in the previous SC with the sunspot number (SSN) of the following SC. Assuming January 2008 as the minimum for SC 24, the shape and amplitude of SC 24 is estimated in terms of monthly mean and smoothed monthly SSN. This new prediction model estimates an average SC 24, with the maximum occurring around June 2012 [AE10 months] with a smoothed monthly maximum SSN of 117:5 AE 8:5.

1] This study documents decadal-scale changes in the Holton and Tan (HT) relationship, i.e., the influence of the lower stratospheric equatorial quasi-biennial oscillation (QBO) on the northern hemisphere (NH) extratropical circulation. Using a combination of ECMWF ERA-40 Reanalysis and Operational data from 1958-2006, we find that the Arctic stratosphere is indeed warmer under easterly QBO and colder under westerly QBO. During November to January, composite easterly minus westerly QBO signals in zonal wind extend from the lower stratosphere to the upper stratosphere and are centered at $5 hPa, 55-65°N with a magnitude of $10 m s À1 . In temperature, the maximum signal is near $20-30 hPa at the pole with a magnitude of $4 K. During winter, the dominant feature is a poleward and downward transfer of wind and temperature anomalies from the midlatitude upper stratosphere to the high latitude lower stratosphere. For the first time, a statistically significant decadal scale change of the HT relationship during 1977-1997 is diagnosed. The main feature of the change is that the extratropical QBO signals reverse sign in late winter, resulting in fewer and delayed major stratospheric sudden warmings (SSWs), which occurred more often under westerly QBO. Consistent with earlier studies, it is found that the HT relationship is significantly stronger under solar minima overall, but the solar cycle does not appear to be the primary cause for the detected decadal-scale change. Possible mechanisms related to changes in planetary wave forcing are discussed. Citation: Lu, H., M. P. Baldwin, L. J. Gray, and M. J. Jarvis (2008), Decadal-scale changes in the effect of the QBO on the northern stratospheric polar vortex,

Annual growth rates and the ratio of dark to light-colored calcite within single annual laminae in three contemporaneously deposited Holocene speleothems from Grotta di Ernesto, an Alpine cave in northern Italy, respond to changes in surface temperature rather than precipitation. Based on monitoring of present-day calcite growth, and correlation with instrumental data for surface climatic conditions, we interpret a higher ratio of dark to light-colored calcite and the simultaneous thinning of annual laminae as indicative of colder-than-present winters. Such dark and thin laminae occur in those parts of the three stalagmites deposited from AD 1650 to 1713 and from AD 1798 to 1840, as reconstructed through lamina counting. These periods correspond to the well-known Maunder and Dalton Minima of solar activity. An 11-yr cyclicity in growth rate, coupled with reduced calcite deposition during the historic minima of solar activity, is indicative of a solar influence on lamina thickness. Spectral analysis of the lamina thickness data also suggests that the North Atlantic Oscillation variability influenced winter temperatures. Based on the present-day controls on cave calcite formation, we infer that high-frequency changes in solar activity modulated the seasonal duration of soil CO 2 production. ß

This second part of a two-paper series compares deterministic precipitation forecasts from the Storm-Scale Ensemble Forecast System (4-km grid) run during the 2008 NOAA Hazardous Weather Testbed (HWT) Spring Experiment, and from the Canadian Global Environmental Multiscale (GEM) model (15 km), in terms of their ability to reproduce the average diurnal cycle of precipitation during spring 2008. Moreover, radar-based nowcasts generated with the McGill Algorithm for Precipitation Nowcasting Using Semi-Lagrangian Extrapolation (MAPLE) are analyzed to quantify the portion of the diurnal cycle explained by the motion of precipitation systems, and to evaluate the potential of the NWP models for very short-term forecasting.

This paper presents results from a study of GPS total electron content (TEC) grid maps and ionospheric electron content (IEC) over the oceans delivered by the TOPEX/Jason satellites during half a solar cycle (July 2001 to December 2008). The IEC data are averaged and binned at latitudes from 60°S to 60°N in steps of 5°±2.5°, at longitudes from 180°W to 180°E in steps of 15°±7.5°, and for 0-23 h UT in steps of 1±0.5 h UT. The ratio of monthly averaged TEC/IEC over the oceans from the observations was compared to the reference model ratio of TECm/IECm obtained using the plasmaspheric model augmented with the International Reference Ionosphere. By definition, TEC should exceed IEC by the plasmaspheric electron content (PEC) contribution at the altitude range from 1336~km (TOPEX orbit) to 20,200 km (GPS orbit). However, as solar activity tends to the minimum, we found that IEC estimates systematically exceed those of GPS TEC. An empirical scale factor was derived in terms of the smoothed sunspot number, and this factor reduced the systematic excess of the TOPEX/Jason-derived IEC over the GPS TEC by a factor of 1.5 towards the solar minimum. This factor was tested with observations made at the solar minimum and revealed that the plasmaspheric electron content to be a residual of the GPS TEC and modified TOPEX/Jason IEC.

During the studied period 1996-2007 I noticed that, the rising and oscillations of the sea level, global temperature, carbon dioxide concentration, ice mass of Antarctica, and melting of Greenland ice are highly correlated with Earth's orbital perturbations. Monthly variations of those parameters have two periodicities. Stronger one called “long-periodic cycle”, it is strongly related to solar activity. It appears as a rising trend during my studied period. Observation data of iceberg mass and its melting, global sea level, and concentration of greenhouse gases such as carbon dioxide is recent and does not cover a millennium or Wolf-Gleissberg solar cycle. So, it does not indicate a global warming. Second cycle is called “short-periodic cycle”. it is a weaker force but still stronger than human activities forcing. It appears as oscillations around the rising trend. The short periodic cycle of all mentioned parameters is found correlated to Earth's orbital perturbations which are indicating a global warming and global warming is a natural phenomenon. Global warming is strongly corelated to Sun, Earth’s orbit, and our  space.  I conclude that the productivity of natural greenhouse gases is greater than that produced by human activity. The current proposed global warming is not a result of human activities, rather just temporary epoch and natural phenomena. The Earth's orbital perturbations are in an excellent positive coherence with the Greenland ice mass but in a negative coherence with the Antarctic ice mass. My results are in good agreement with Yousef (2000) and Akasofu (2010).  I propose that the natural source of rising in concentration of greenhouse gases can be attributed to two causes: 1) Comets and asteroids, which are still carrying water molecules and some of greenhouse gas’ molecules to the Earth’s atmosphere; 2) Solar wind, which is composed greenhouse gases in ionization state. It may react and recombined though upper atmosphere before arriving to atmospheric lower levels at poles by unknown process. The global temperature is found to be correlated to Earth’s orbital perturbation too. This is because the declination angle is varying through the year. Output solar energy that arrives to the Earth depends on Sun-Earth distance too.

This study presents the continuous GPS network in Vietnam and the results of study on time variations of the total electron content (TEC) in the South East Asian equatorial ionization anomaly (EIA) for the 2006-2013 period. In each year we observe a semiannual pattern of amplitude of the EIA crests with its maximum amplitude at equinox. In both hemispheres, the amplitude of the crest is larger in northern spring equinox than in autumn from 2006 to 2008 (descending phase of solar cycle) and smaller in spring than in autumn from 2009 to 2011 (increasing phase of solar cycle), from 2012-2013 (maximum period of solar cycle) the amplitudes of the crests in spring and autumn are equivalent. We also observe an asymmetry between the amplitude and the position of the two crests of ionization. There is a very high level of correlation between the amplitude of the TEC at the two crests and the sunspot number is approximately equal to 0.9. During the deep solar minimum 2008-2009, the amplitude of crests of ionization becomes small during several months in summer and winter (about 20 TECu). The results show that both crests move more significantly equatorward in winter than in other seasons and there is a tendency for both crests to appear earlier in winter and later in summer. In the solar minimum years, the amplitudes of the crests are minimal; the positions of the crests are nearer the magnetic equator and the crests appear earlier than in other years.

For a given galactic cosmic ray (GCR) environment, understanding the distribution of the particle flux (protons, alpha particles, and heavy ions) in deep-space and on the surface of planetary systems such as Mars are essential for the risk assessment of future human exploration missions. In our model calculations, we make use of the NASA's HZETRN (High Z and Energy Transport) code along with the nuclear fragmentation cross sections that are described by the quantum multiple scattering (QMSFRG) model with the time-dependant variation of the GCR environment derived making use of the solar modulation potential, phi. Data from the cosmic ray isotope spectrometer (CRIS) instrument onboard the advanced composition explorer (ACE) has been available from 1998. Data from the CRIS instrument is being analyzed to understand the short term variations in the particle spectrum during the current solar cycle phase. In this report, particle spectrum for December 2002 of the CRIS instrument was compared with the model calculations. Current assessment of the model calculations show very good agreement of the particle flux (∼ 15% for low Z and ∼ 5% for high Z) data from Boron (Z = 5) through Nickel (Z = 28) nuclei for the energy bins reported by CRIS. Similarly, the model calculated dose-rate calculations are compared with the proton flux measured dose-rate from the Martian Radiation Environment Experiment (MARIE) currently onboard the 2001 Mars Odyssey spacecraft in Martian orbit for the month of August 2003 that is representative of a quiet-time GCR data at Mars. Current model calculations are well within 10% of the measured observations of MARIE. The predictive capabilities of the quiet-time GCR particle flux model calculations are promising for biological and shielding studies and for the radiation risk assessment for future human explorations.

Over the 11-year solar cycle, small changes in the total solar irradiance (TSI) give rise to small variations in the global energy budget. It was suggested, however, that different mechanisms could amplify solar activity variations to give large climatic effects, a possibility which is still a subject of debate. With this in mind, we use the oceans as a calorimeter to measure the radiative forcing variations associated with the solar cycle. This is achieved through the study of three independent records, the net heat flux into the oceans over 5 decades, the sea-level change rate based on tide gauge records over the 20th century, and the sea-surface temperature variations. Each of the records can be used to consistently derive the same oceanic heat flux. We find that the total radiative forcing associated with solar cycles variations is about 5 to 7 times larger than just those associated with the TSI variations, thus implying the necessary existence of an amplification mechanism, although without pointing to which one.

Tavares and Azevedo [1] showed in their article, that there existed a correlation between the solar cycles and the earthquake activity. In their study they used both ancient records, as well as recent seismicity between 1950 and 2010. According to them, a possible link between solar activity and earthquake occurrence is the magnetic field of the earth, that is being changed in shape corresponding to the solar cycles and thus exerts a pressure on the earth's crust. This study tries to test their results by means of correlation and cointegration, not only using recent solar and earthquake data, but also taking measurements of the Earth's magnetic field strength into account. The results presented in this work show no clear connection between the seismicity and the 11-year solar cycles. The data rather indicates an anti-periodicity. It is not excluded, that a few strong CME events can influence the triggering of earthquake events, however, this effect is presumably small and plays only a minor roll in the faulting process. Figure 1. Above: Daily mean of the observed number of Sunspots showing the solar cycles between 1950 and 2010. Below: Spectral analysis shows a clear peak at an approx. 11 year period in the solar cycles.

Astronomers have observed sunspot cycles ever since 1600 with a period that varies from 10-12y and from no spots per day at the minima to over 300 spots per day at the maxima. Although there are a great number of analyses of sunspot activity, there has not as yet been an explanation for the periodicity of sunspot activity. However, the collapse of quantum aether that unites gravity and charge forces also results in a gravity vector force called quadrupole gravitization. Quadrupole gravitization couples star motion and is responsible for galaxy rotation and gravitization also affect the sun and other stars convection as well.

The matter decay and motion of our sun couples with the matter decays and motions of nearby binary stars, Procyon and 61-Cygni, which are both 11.4 light years (lyrs) away. This coupling results in a periodic change in solar convection that is the sunspot cycle. The proximity of these two binary stars along with the periods of these two binary stars correlate well with the period and variation of sunspot activity, both the variation of period and the variation of amplitude.

Notably, the Maunder minimum correlates well with the separation of the 61-Cygni binary star. The Maunder minimum was a notably lack of sunspots that lasted from about 1660 to 1700 and coincided with a period of lower temperatures on earth, the so-called little ice age.

A high-resolution multi-proxy analysis was conducted on a 1.5-m-long core of Tortonian age (~10.5 Ma; Late Miocene) from Austria (Europe). The lake sediments were studied with a 1-cm resolution to detect all small-scale variations based on palynomorphs (pollen and dinoflagellate cysts), ostracod abundance, geochemistry (carbon and sulfur) and geophysics (magnetic susceptibility and natural gamma radiation). Based on an already established age model for a longer interval of the same core, this sequence can be limited to approx. two millennia of Late Miocene time with a resolution of~13.7 years per sample. The previous study documented the presence of solar forcing, which was verified within various proxies on this 1.5-m core by a combination of REDFIT spectra and Gaussian filters. Significant repetitive signals ranged in two discrete intervals corresponding roughly to 55-82 and 110-123 years, fitting well within the lower and upper Gleissberg cycle ranges. Based on these results, the environmental changes along the 2000-year Late Miocene sequence are discussed. No major ecological turnovers are expected in this very short interval. Nonetheless, even within this brief time span, dinoflagellates document rapid changes between oligotrophic and eutrophic conditions, which are frequently coupled with lake stratification and dysoxic bottom waters. These phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria. The pollen record indicates rather stable wetland vegetation with a forested hinterland. Shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms. These are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction. Such influence is most likely caused by solar cycles, leading to a change in source area for the input into the lake. Furthermore, these solar-induced variations seem to be modulated by longer solar cycles. The filtered data display comparable patterns and modulations, which seem to be forced by the 1000-year and 1500-year cycles. The 1000-year cycle modulated especially the lake surface proxies, whereas the 1500-year cycle is mainly reflected in hinterland proxies, indicating strong influence on transport mechanisms.

Tritium of the precipitation plays a very important role in the study of the waters of our planet because its tracer property is suitable for a better understanding of atmospheric and hydrological processes. Since the atmospheric test-ban treaty, the bomb tritium concentrations in precipitation have significantly reduced. Therefore, in the last two decades, global tritium concentration of precipitation (including anthropogenic and natural sources) have nearly reached a steady state level.
The aim of this study is to explore the variability of natural tritium in the past by using the neutron monitor time series, which represents the variability of solar activity. Many previous studies focused on the reconstruction of the bomb-tritium time series, taking into account the long tritium time series of some cities (Ottawa, Vienna, Tokyo). In our study, we primarily estimate the tritium of natural origin in the northern and southern hemispheres, which may be an important input parameter for atmospheric and hydrological modeling. Therefore, we been
have developed a statistical model to estimate short and long term changes in natural tritium. This estimate is based on the relationship between the global tritium time series and the neutron flux. The statistical model provides a relatively accurate estimate for stations that are poor in technogenic sources of tritium since time series values closely follow seasonal and long-term changes. Whereas for time series that are richer in technogenic tritium, the estimation is less accurate because the tritium values of the time series do not change regularly, that is, they do not follow the natural change.

The authors examine the mechanism of solar cycle modulation of the Quasi-Biennial Oscillation (QBO) period using the Two-and-a-Half-Dimensional Interactive Isentropic Research (THINAIR) model. Previous model results (using 2D and 3D models of varying complexity) have not convincingly established the proposed link of longer QBO periods during solar minima. Observational evidence for such a modulation is also controversial because it is only found during the period from the 1960s to the early 1990s, which is contaminated by volcanic aerosols. In the model, 200-and 400-yr runs without volcano influence can be obtained, long enough to establish some statistical robustness. Both in model and observed data, there is a strong synchronization of the QBO period with integer multiples of the semiannual oscillation (SAO) in the upper stratosphere. Under the current level of wave forcing, the period of the QBO jumps from one multiple of SAO to another and back so that it averages to 28 months, never settling down to a constant period. The ''decadal'' variability in the QBO period takes the form of ''quantum'' jumps; these, however, do not appear to follow the level of the solar flux in either the observation or the model using realistic quasi-periodic solar cycle (SC) forcing. To understand the solar modulation of the QBO period, the authors perform model runs with a range of perpetual solar forcing, either lower or higher than the current level. At the current level of solar forcing, the model QBO period consists of a distribution of four and five SAO periods, similar to the observed distribution. This distribution changes as solar forcing changes. For lower (higher) solar forcing, the distribution shifts to more (less) four SAO periods than five SAO periods. The record-averaged QBO period increases with the solar forcing. However, because this effect is rather weak and is detectable only with exaggerated forcing, the authors suggest that the previous result of the anticorrelation of the QBO period with the SC seen in short observational records reflects only a chance behavior of the QBO period, which naturally jumps in a nonstationary manner even if the solar forcing is held constant, and the correlation can change as the record gets longer.

Tavares and Azevedo [1] showed in their article, that there existed a correlation between the solar cycles and the earthquake activity. In their study they used both ancient records, as well as recent seismicity between 1950 and 2010. According to them, a possible link between solar activity and earthquake occurrence is the magnetic field of the earth, that is being changed in shape corresponding to the solar cycles and thus exerts a pressure on the earth's crust. This study tries to test their results by means of correlation and cointegration, not only using recent solar and earthquake data, but also taking measurements of the Earth's magnetic field strength into account. The results presented in this work show no clear connection between the seismicity and the 11-year solar cycles. The data rather indicates an anti-periodicity. It is not excluded, that a few strong CME events can influence the triggering of earthquake events, however, this effect is presumably small and plays only a minor roll in the faulting process. Figure 1. Above: Daily mean of the observed number of Sunspots showing the solar cycles between 1950 and 2010. Below: Spectral analysis shows a clear peak at an approx. 11 year period in the solar cycles.

We suggest that the average of the sunspot number (SSN) over a cycle offers a more appropriate index than the maximum value of the SSN in the evaluation of the activity of solar cycles. We then show that the average SSN has a tendency to take discrete values, that is, integral multiples of 20. This remarkable finding is supported by the fact that SSNs around the maximum are likely to take some particular values. Further, it is shown that there exists a positive correlation in the amplitude between even-numbered cycles and succeeding odd-numbered cycles and an inverse correlation between (2n + 1) cycles and (2n + 4) cycles where n represents an integer. If these two correlations are combined, it turns out that there exist two mutually independent series of cycles which do not mix or merge.

The study of climate is one of the most complex and most multidisciplinary areas of research known to science. Models are used, which are mathematical representations of forcings, interactions and feedbacks of all the variables that affect climate. Most models are driven by atmospheric physics and play an important role in our understanding of the Earth's climate and how it will likely change in the future. An extensive review of the scientific literature reveals a striking simplification of solar output and its impact on climate. The well-known 11-year cycles are represented but there is no representation of longer cycles such as the Gleissberg 88-year cycle and the Devries 208-year cycle. The reason for the omission is most likely the fact that multi-decadal solar cycles are poorly understood as to their occurrence, strength and periodicity. Nonetheless, the longer cyclicalities appear to be present in the observed temperatures. The absence of important forcing factors from the models has led to a theory that is fundamentally underdetermined. There are fewer interactions and feedbacks in the models and too many unknown variables and degrees of freedom. An underdetermined system typically has many solutions. In other words, there can be other theories that are compatible with the same set of observations. This study presents a reduced model of six elements of natural variability that are not currently included in the models: four solar decadal cycles and two decadal oceanic oscillations. Monte-Carlo simulations are performed on the six stochastic natural variables and are shown to produce patterns similar to the observed patterns published in the literature.

A B S T R A C T We analyzed 17 years (1993–2009) of horizontal winds measured by the medium frequency (MF) radar located at Tirunelveli (8.7°N, 77.8°E) and 10 years (2005–2014) of horizontal winds measured by a meteor radar located at Thumba (8.5°N, 77°E) to examine the seasonal, inter-annual, and solar cycle variability of the Quasi-Two Day Wave (QTDW) in the mesosphere and lower thermosphere region. These two radars are nearly co-located, but differ in their measurement technique. Comparison of the estimated QTDW amplitudes by the two radars shows that the amplitudes are larger in the meteor radar than those in the MF radar. The difference between the amplitudes is larger in May in the zonal component and in April and September in the meridional one. Furthermore, the differences are larger in the meridional component. The QTDWs in both the radars show a strong semi-annual oscillation (SAO). In addition, the meridional QTDW amplitudes of both the MF and meteor radars show a distinct enhancement in the month of October. While the whole spectra of QTDWs contribute to the SAO amplitudes, only 45–50 h waves contribute to the October enhancement. The amplitudes of the QTDWs, in general, show large inter-annual variability. The QTDW amplitudes from both the radars show modulation at period of quasi-biennial oscillation. The QTDWs of the MF radar show a small negative correlation with solar activity while those of meteor radar do not show any correlation. The above aspects are discussed in the light of current understanding of the QTDWs.

The Sun encompasses planet Earth, supplies the heat that warms it, and even shakes it. The United Nation Intergovernmental Panel on Climate Change (IPCC) assumed that solar influence on our climate is limited to changes in solar irradiance and adopted the consensus opinion of a Hydrogen-filled Sun, the Standard Solar Model (SSM). They did not consider the alternative solar model and instead adopted another consensus opinion: Anthropogenic greenhouse gases play a dominant role in climate change. The SSM fails to explain the solar wind, solar cycles, and the empirical link of solar surface activity with Earth changing climate. The alternative solar model, that was molded from an embarrassingly large number of unexpected observations revealed by space-age measurements since 1959, explains not only these puzzles but also how closely linked interactions between the Sun and its planets and other celestial bodies induce turbulent cycles of secondary solar characteristics that significantly affect Earth climate.

A high-resolution multi-proxy analysis was conducted on a 1.5-m-long core of Tortonian age (~10.5 Ma; Late Miocene) from Austria (Europe). The lake sediments were studied with a 1-cm resolution to detect all small-scale variations based on palynomorphs (pollen and dinoflagellate cysts), ostracod abundance, geochemistry (carbon and sulfur) and geophysics (magnetic susceptibility and natural gamma radiation). Based on an already established age model for a longer interval of the same core, this sequence can be limited to approx. two millennia of Late Miocene time with a resolution of~13.7 years per sample. The previous study documented the presence of solar forcing, which was verified within various proxies on this 1.5-m core by a combination of REDFIT spectra and Gaussian filters. Significant repetitive signals ranged in two discrete intervals corresponding roughly to 55-82 and 110-123 years, fitting well within the lower and upper Gleissberg cycle ranges. Based on these results, the environmental changes along the 2000-year Late Miocene sequence are discussed. No major ecological turnovers are expected in this very short interval. Nonetheless, even within this brief time span, dinoflagellates document rapid changes between oligotrophic and eutrophic conditions, which are frequently coupled with lake stratification and dysoxic bottom waters. These phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria. The pollen record indicates rather stable wetland vegetation with a forested hinterland. Shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms. These are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction. Such influence is most likely caused by solar cycles, leading to a change in source area for the input into the lake. Furthermore, these solar-induced variations seem to be modulated by longer solar cycles. The filtered data display comparable patterns and modulations, which seem to be forced by the 1000-year and 1500-year cycles. The 1000-year cycle modulated especially the lake surface proxies, whereas the 1500-year cycle is mainly reflected in hinterland proxies, indicating strong influence on transport mechanisms.

In this paper, we present an overview of radio signatures of sunspot NOAA 12192 measured with various instruments with frequencies of 37 GHz, 11.2 GHz and 200 - 400 MHz at Aalto University Metsahovi Radio Observatory (MRO). The data were observed during October 20 - 29, 2014. In total, 12 solar radio bursts at 11.2 GHz and 8 at 200 - 400 MHz, with varying intensities and properties, were observed. Radio brightening was captured in several solar radio maps. NOAA 12192 is the largest observed sunspot during solar cycle 24. We show that this exceptional radio brightening belongs to the strongest category including less than 5% of radio brightenings ever measured at MRO.

A statistical study of the effects of the solar cycle, as indicated by the value of F10.7, has been made utilizing a data base of electrostatic shocks and the associated ion beams, ion conics, and electron distributions obtained by the S3-3 satellite during the rising phase of the solar cycle. Ion composition was not included since the ion detectors utilized for this study did not determine mass. The acceleration of ions in association with electrostatic shocks is strongly dependent on F10.7 at altitudes of-2000 -8000 km. For low F10.7 (<80), -43% of the shocks were associated with conics and -43% with beams, whereas for high F10.7 (100-225), -18% of the shocks were associated with beams and -64% with conics. This difference was observed for essentially all magnetic local times and altitudes except the period from 0000 -0600 MLT. These results suggest that parallel potential drops are less common at altitudes below 8000 km during solar maximum than during solar minimum. However, for the events where ion beams were observed, the average parallel potential drop below the satellite (as determined from the peak ion energy) had very similar values, and approximately half of the potential occurred below the satellite altitude for both high and low F10.7.

By how much does the Sun's radiation vary? Although the Sun has long been an object of immense fascination, fundamental information about the magnitude and variability of its radiative output, sought for over a century, is only now approaching a level satisfactory for geophysical applications. During the past decade, satellite instruments have measured, simultaneously, both the Sun's spectrally integrated radiative output and its ultraviolet spectrum. These data have been analyzed in terms of their relationships to ground-based observations that characterize different aspects of the Sun's 11-year activity cycle, allowing estimates of solar radiative output variations over times scales from days to decades and interpretations of these variations in the broader context of the variable Sun. Uncertainties still remain to be answered by the next generation of solar radiometers, which commenced observations with the launch of the Upper Atmosphere Research Satellite in September 1991, near the maximum of solar cycle 22. radiator at-5770øK, is modulated by solar activity. The largest amplitude variations, reaching more than an order of magnitude, occur in the wings of the blackbody spectrum, at ultraviolet and radio wavelengths [White, 1977]; visible emissions near the peak of the blackbody curve are comparatively invariant. These visible emissions dominate the spectrally integrated (total) solar irradiance (historically misnamed the "solar constant"), which varied by-0.1% from the maximum to the minimum of solar cycle 21. Planetary atmospheres, comets, and the local interplanetary medium scatter, absorb, and reemit solar radiation at many different wavelengths, depending on their compositions [e.g., Chamberlain, 1978]. Variations in solar radiative output are therefore expected to cause changes in the chemistry, dynamics, and radiative properties of solar system bodies. Because the Sun is the This paper is not subject to U.S. copyright.

Of the ancient manuscripts that have survived to this day, the books from ancient Mexico (Mesoamerica), also called codices, belong to a very special group, namely those of picture writing. The Codex Borbonicus is a unique example of this preserved group of codices with picture writing. In addition to the complete depiction of the ritual 260 solar day almanac and the 365 solar day calendar with the 18 ritual agricultural holiday periods, this codex also has a complete 52 solar year cycle with both the year names and the 9 night deities. This combination does not appear in any of the other surviving codices.
In the literature, however, little attention is paid to this 52 solar year cycle, so important in ancient Mesoamerica before the Spanish invasion, which was closely intertwined with the Pleiades star group, which is said to have been closely watched at the close of each 52nd solar year. However, an extensive analysis shows that the 52 solar year cycle shown on pages 21 and 22 of the Codex Borbonicus contains a large number of errors, which are explained in detail in word and image in this paper.

Prediction of maximum amplitude of Solar Cycle 25 is obtained by using four different machine learning regression methods, i.e. Linear Regression (LR), Random Forest (RF), Radial Basis Function (RBF) and Support Vector Machine (SVM). Monthly mean sunspot number data during the 1856-June 2018 (solar cycles 10-24) from the World Data Center SILSO, Royal Observatory of Belgium, Brussels are used as machine learning inputs. According to LR, RF, RBF and SVM, the maximum of Solar Cycle 25 is predicted to occur in September 2023 (sunspot number of 159.4 ± 22.3), in December 2024 (sunspot number of 110.2 ± 12.8), in December 2024 (sunspot number of 95.5 ± 21.9) and in July 2024 (sunspot number of 93.7 ± 23.2), respectively. The prediction using the LR method suggested that Solar Cycle 25 maximum
will be slightly higher than the current cycle, while RBF and SVM suggested much lower cycles. RF prediction suggested a lower maximum with well-constructed double-peak. It was also found that Solar Cycle 25 is predicted to begin in the late 2019 or early 2020 according to all four methods.

It is well known that there are profound effects of solar cycle (SC) on the tropical deep convection and hence the atmospheric circulations. However, it is unknown how the intensity and duration of SC is going to affect the circulation patterns. In the present study, the effect of SC on the Hadley circulation (HC) is investigated based on intensity and duration of the SC using ERA-Interim dataset obtained during 1979-2012. Maximum and minimum SC is differentiated based on sunspot number (SSN) with cutoff at >=100 and <=20 for solar maximum and minimum, respectively. The duration of solar maximum (minimum) and its peak intensity are found decreasing (increasing) from SC 21 to SC 23. During solar maximum, convection shifts southward over South Ameri-can and African (10oS) sectors and no convection over Indian and adjoining sectors. This feature, however, varies from cycle to cycle. It is found that SC with larger intensity causes the convection centres to shift to Pacific i.e. zonally (EW) and longer duration in SC causes the convective centres to shift to southward i.e. meridionally (NS). Mass stream function analysis reveals that the HC decreased in SC 22 compared to SC 21 and SC 23 against increase or no change in the pacific region. This is attributed to the persistence of high sunspot activity for a larger period. HC is relatively strong in SC 21suggesting the influence of solar activity is relatively more in SC 21 compared to SC 23. Even though the duration of SC 23 is more (12.6 years), the SSN is less (120.8) compared to the SC 21 (10.9 years with peak SSN 164). This strong and less period of solar activity might be the reason for relatively strong influence of solar activity on SC 21 compared to SC 23. In addition, the spotless days are very less during SC 21 (273 days) compared to SC 23 (821 days). Thus, it is observed that Southern Hemisphere HC is strongly influenced (reduced) during solar maximum which depends further on the duration and intensity. Less duration causes more influence on HC.

1] In spite of many recent developments in observations and models of the solar corona, the exact form of the heating function of the solar wind plasma is unknown. Here we attempt to make some progress on that problem by applying a previously developed simplified magnetohydrodynamic model to a unique synthesis of remote sensing coronal observations from SOHO and Spartan 201, and in-situ data from Ulysses spacecraft during the quiescent phase of solar cycle 23 (1995)(1996)(1997) which also included the Whole Sun Month (August/September 1996) study period. Our analysis provides for the first time an empirically derived estimate of the heat flux and temperature profile of the corona and interplanetary medium over the solar polar regions as a function of latitude and radial distance for this data set. The latitudinal and radial variation is extended to include the equatorial regions but with less fidelity given the significant structure associated with the streamer belt. Our results suggest that both thermal and nonthermal heating terms contribute to the temperature and heat flux in the low corona, particularly above the poles, with the non-thermal component possibly providing as much as half of the total heat input.

The protection of astronauts from space radiation is required on future exploratory class and long-duration missions. For the accurate projections of radiation doses, a solar cycle statistical model, which quantifies the progression level within the cycle, has been developed. The resultant future cycle projection is then applied to estimate the mean frequency of solar particle events (SPEs) in the near future using a power law function of sunspot number. Detailed temporal behaviors of the recent large event and two historically large events of the August 1972 SPE and the November 1960 SPE are analyzed for dose-rate and cumulative dose equivalent at sensitive organs. Polyethylene shielded "storm shelters" inside spacecraft are studied to limit astronauts' total exposure at a sensitive site within 10 cSv from a large event as a potential goal that fulfills the ALARA (as low as reasonably achievable) requirement.

'Computational History' derives history from data and nowadays, therefore, relies on the technologies of the digital humanities. 'Computational History of Science' addresses questions of history by evaluating historical data, e.g. for tracing back copying traditions and conclude on transfer and transformation of data and knowledge. The term 'Applied Historical Astronomy', in contrast, tries to address questions of contemporary science by evaluating historical data in comparison with most recent data. This opens new possibilities, e.g. in the search for stellar transients among historical data.
In the contribution by Hoffmann & Vogt we will focus on the stellar transients among all the topics mentioned above. Philipp Protte discusses the accuracy of magnitudes and positions in ancient star catalogues, Andreas Schrimpf & Frank Verbunt present an analysis of an early modern star catalogue. Victor Reijs analyses the visibility of celestial objects for naked-eye observers, and Björn Kunzmann showcases some important variable stars in the history of astronomy. Rene Hudec presents astronomical photographic archives as a valuable data source for modern astrophysics. José M. Vaquero discusses the studies on solar observations made during the last four centuries. More technical are the contributions of Georg Zotti on 'Stellarium' and Karsten Markus-Schnabel on data-mining and data-processing technologies. Ido Yavetz & Luca Beisel are developing a digital tool of computational history of science for the simulation of pre-modern astronomical models. Gerd Graßhoff focuses more on the application of computational history with regard to Kepler's Astronomia Nova while Tim Karberg presents an analysis of the astronomical orientation of buildings in the North Sudan.

Wolfschmidt, Gudrun & Susanne M. Hoffmann (ed.):
Applied and Computational Historical Astronomy.
Angewandte und computergestützte historische Astronomie. Proceedings of the Splinter Meeting in the Astronomische Gesellschaft, Sept. 25, 2020. Hamburg: tredition (Nuncius Hamburgensis - Beiträge zur Geschichte der Naturwissenschaften; Bd. 55) 2021.
ISBN 978-3-347-27104-3 (Paperback), 978-3-347-27105-0 (Hardcover), 978-3-347-27106-7 (e-Book), (344 pages, 108 pages in colour). ISBN 978-3-949060-02-1 (computational Book), ©OpenScienceTechnology GmbH Berlin.

It is well known that there are profound effects of solar cycle (SC) on the tropical deep convection and hence the atmospheric circulations. However, it is unknown how the intensity and duration of SC is going to affect the circulation patterns. In the present study, the effect of SC on the Hadley circulation (HC) is investigated based on intensity and duration of the SC using ERA-Interim dataset obtained during 1979-2012. Maximum and minimum SC is differentiated based on sunspot number (SSN) with cutoff at >=100 and <=20 for solar maximum and minimum, respectively. The duration of solar maximum (minimum) and its peak intensity are found decreasing (increasing) from SC 21 to SC 23. During solar maximum, convection shifts southward over South Ameri-can and African (10oS) sectors and no convection over Indian and adjoining sectors. This feature, however, varies from cycle to cycle. It is found that SC with larger intensity causes the convection centres to shift to Pacific i.e. zonally (EW) and longer duration in SC causes the convective centres to shift to southward i.e. meridionally (NS). Mass stream function analysis reveals that the HC decreased in SC 22 compared to SC 21 and SC 23 against increase or no change in the pacific region. This is attributed to the persistence of high sunspot activity for a larger period. HC is relatively strong in SC 21suggesting the influence of solar activity is relatively more in SC 21 compared to SC 23. Even though the duration of SC 23 is more (12.6 years), the SSN is less (120.8) compared to the SC 21 (10.9 years with peak SSN 164). This strong and less period of solar activity might be the reason for relatively strong influence of solar activity on SC 21 compared to SC 23. In addition, the spotless days are very less during SC 21 (273 days) compared to SC 23 (821 days). Thus, it is observed that Southern Hemisphere HC is strongly influenced (reduced) during solar maximum which depends further on the duration and intensity. Less duration causes more influence on HC.

1] Over the 11-year solar cycle, small changes in the total solar irradiance (TSI) give rise to small variations in the global energy budget. It was suggested, however, that different mechanisms could amplify solar activity variations to give large climatic effects, a possibility which is still a subject of debate. With this in mind, we use the oceans as a calorimeter to measure the radiative forcing variations associated with the solar cycle. This is achieved through the study of three independent records, the net heat flux into the oceans over 5 decades, the sea-level change rate based on tide gauge records over the 20th century, and the sea-surface temperature variations. Each of the records can be used to consistently derive the same oceanic heat flux. We find that the total radiative forcing associated with solar cycles variations is about 5 to 7 times larger than just those associated with the TSI variations, thus implying the necessary existence of an amplification mechanism, although without pointing to which one. Citation: Shaviv, N. J. (2008), Using the oceans as a calorimeter to quantify the solar radiative forcing,

Solar spectral fluxes (or irradiance) measured by the SOlar Radiation and Climate Experiment (SORCE) show different variability at ultraviolet (UV) wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S). Some modelling studies have suggested that stratospheric/lower mesospheric O 3 changes during solar cycle 23 (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM), forced by meteorology from the European Centre for Medium-Range Weather Forecasts (ECMWF), to simulate middle atmospheric O 3 using three different solar flux data sets (SORCE, NRL-SSI and SATIRE-S). Simulated O 3 changes are compared with Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite data. Modelled O 3 anomalies from all solar flux data sets show good agreement with the observations, despite the different flux variations. The off-line CTM reproduces these changes through dynamical information contained in the analyses. A notable feature during this period is a robust positive solar signal in the tropical middle stratosphere, which is due to realistic dynamical changes in our simulations. Ozone changes in the lower mesosphere cannot be used to discriminate between solar flux data sets due to large uncertainties and the short time span of the observations. Overall this study suggests that, in a CTM, the UV variations detected by SORCE are not necessary to reproduce observed stratospheric O 3 changes during 2001-2010.

We have studied the effect of both solar magnetic polarity and the solar wind velocity on the Bz-component of the interplanetary magnetic field, IMFBz, for the minimum activity of the solar cycles 21, 22, 23 and 24. We made a statistical study of IMFBz in the first section which is considered as an extension of Lyatsky et al. (2003). They made a statistical study of IMFBz for two periods of minimum solar activity 22 and 23 related to 1985–1987 and 1995–1997 when the solar magnetic field had opposite polarity. Our results seem to be consistent with the results obtained by Lyatsky et al. (2003). We found that there is a dependence of IMFBz on the IMFBx and the solar magnetic polarity for the minimum periods of the selected four solar cycles. In addition, we found that there is a dependence of IMFBz on the solar wind velocity.

Sunspots are dark spots on the surface of the Sun. They last from days to months. According to common knowledge the number of sunspots varies according to a 11-year solar cycle and the origin of sunspot development is still a matter of research (1). Sunspot variations may have effects on earth. This article presents a clear correlation between the Jupiter-Saturn cycle and the solar cycle and postulates that the basic solar cycle time is 10 years.

In this study, we are investigating the solar flare events during each Carrington rotation in the period 2002-2017. We studied the relationship between solar flare event location and solar cycle progress (phases). The solar flare events are tending to accumulate around a specific latitude line in the southern and northern hemispheres of the solar disk, which we call the "eruptive latitude". The eruptive latitude is migrating towards the solar equator during the declining phase and away from the solar equator during the ascending phase. The eruptive latitude is consistent with the sunspot butterfly diagram. We found the suitable equation describing the relationship between the eruptive latitude ϕ and the Carrington rotation number CR using sinusoidal summation function.

In the present study, long-term trends in the diurnal tide in the troposphere and stratosphere over a tropical station Gadanki (13.5°N, 79.2°E) are investigated using ERA-Interim wind and temperature products available since 1979. Suitability of the ERA-Interim data for the present study is ascertained using simultaneous radiosonde and MST radar observations over Gadanki and good consistency was found between the two. In general, diurnal tide amplitudes are found to increase from troposphere to stratosphere, as expected. Amplitude of the diurnal tide shows a long-term linear increasing trend, which becomes prominent in the stratosphere. Interestingly, convection over Gadanki also exhibits an increasing trend suggesting that they are related. Role of solar cycle on the diurnal tide is investigated by separating the tidal amplitudes during minimum and maximum of solar cycles 21, 22 and 23. Significantly higher amplitudes in the recent extended solar minimum are noticed though no consistent relation is found between solar activity and tides, in general. These results are discussed in the light of role of convection on the generation of the diurnal tide and their propagation to the higher altitudes, coupling lower and middle atmospheres. Special emphasis is made on the observed large amplitudes of the diurnal tide in the extended solar minimum while relating the observed changes to the background circulation.

The 11-yr solar cycle [decadal solar oscillation (DSO)] at its peaks strengthens the climatological precipitation maxima in the tropical Pacific during northern winter. Results from two global coupled climate model ensemble simulations of twentieth-century climate that include anthropogenic (greenhouse gases, ozone, and sulfate aerosols, as well as black carbon aerosols in one of the models) and natural (volcano and solar) forcings agree with observations in the Pacific region, though the amplitude of the response in the models is about half the magnitude of the observations. These models have poorly resolved stratospheres and no 11-yr ozone variations, so the mechanism depends almost entirely on the increased solar forcing at peaks in the DSO acting on the ocean surface in clear sky areas of the equatorial and subtropical Pacific. Mainly due to geometrical considerations and cloud feedbacks, this solar forcing can be nearly an order of magnitude greater in those regions than the globally averaged solar forcing. The mechanism involves the increased solar forcing at the surface being manifested by increased latent heat flux and evaporation. The resulting moisture is carried to the convergence zones by the trade winds, thereby strengthening the intertropical convergence zone (ITCZ) and the South Pacific convergence zone (SPCZ). Once these precipitation regimes begin to intensify, an amplifying set of coupled feedbacks similar to that in cold events (or La Niña events) occurs. There is a strengthening of the trades and greater upwelling of colder water that extends the equatorial cold tongue farther west and reduces precipitation across the equatorial Pacific, while increasing precipitation even more in the ITCZ and SPCZ. Experiments with the atmosphere component from one of the coupled models are performed in which heating anomalies similar to those observed during DSO peaks are specified in the tropical Pacific. The result is an anomalous Rossby wave response in the atmosphere and consequent positive sea level pressure (SLP) anomalies in the North Pacific extending to western North America. These patterns match features that occur during DSO peak years in observations and the coupled models.

Incoherent scatter radar observations of ion drifts taken at Millstone Hill (42.6øN, 288.5øE) during 73 experiments in the period February 1984 to February 1992 are used to construct, for the first time at this station, average quiet-time ExB drift patterns for both solar cycle maximum and minimum, for the summer, winter, and equinox seasons. The daily variation of V. t2q shows a reversal from northward to southward drifts near noon, and a return to northward drifts in the premidnight hours. The weaker southward drift in the afternoon in summer noted by Wand and Evans (1981) is shown to occur only at sunspot minimum. The daily variation of Va. • shows daytime eastward drifts and nighttime westward drifts, except in summer when the usual daytime eastward maximum near 1200 LT is suppressed. The daily mean drift is westward for all seasons, and is largest in summer. The daytime eastward drift and nighttime westward drift tend to be stronger at solar maximum than at solar minimum. Average drift patterns are also constructed for equinox for both extremely quiet and geomagnetically disturbed periods. V.I.N is appreciably more northward under extremely quiet than under disturbed conditions in the postmidnight and morning periods. During extremely quiet periods, V.m turns slightly eastward in the evening hours, while it is strongly westward for disturbed conditions. This result contrasts with the strong eastward drifts in the evening in summer reported for extremely quiet conditions at Millstone Hill by Gonzales et al. (1978). A strong anticorrelation is seen at Millstone Hill between V.I.N and Vii, as is found at lower latitude stations. The quiet-time patterns are discussed in terms of the causative E and F region dynamo mechanisms. At Millstone Hill, conjugate point electric fields are also important in winter when the conjugate ionosphere is sunlit for much of the night. 15,677 15,678 BUONSANTO Er hE.: F REGION ELECTRODYNAMICS AT MmLSTON• HILL measured by the Dynamics Explorer 2 (DE 2) spacecraft. Richmond et al. [1980] combined solar minimum data from Jicamarca, Arecibo, St. Santin, and Millstone Hill to produce a global empirical model of quiet-time low-middle latitude electric fields. Summer As much additional data are now available, we can contemplate the development of a global model to succexA that of Richmond et al.

1] The magnetic field measured by Voyager 1 (V1) near 85 AU from 2002.0 to 2003.17 has the expected properties for the heliospheric magnetic field at that distance and epoch of the solar cycle. These V1 magnetic field observations do not provide evidence for exit from the solar wind, entry into a subsonic region such as the heliosheath, or transit of the termination shock near 85 AU.

In this paper we present an overview of solar radio observations at 11.2 GHz on Mets?hovi Radio Observatory (MRO). The data were observed during the solar cycles 23 and 24 (2001-2013) both in solar maxima and minimum. In total, 180 solar radio bursts, with varying intensities and properties, were observed. We compare our data series with other similar data sets. A good correlation can be found between the data series. It is concluded that one can conduct scientifically significant solar radio observations with a low cost instrument as the one presented in this paper.

1] To assess a possible solar modulation of the planetary waves, the 300 hPa geopotential height of the two major reanalysis data sets, NCEP/NCAR and ERA40, is studied for the difference between years of solar maximum and minimum activity for three solar cycles in the period 1963-1999. We find a significant positive difference over the North Pacific ocean for December through February which resembles that found in sea level pressures in earlier studies. Furthermore, there are statistically significant amplitude differences in the climatological state of the first two planetary waves extracted from the geopotential heights. We also perform a model study of the middle atmospheric response to the tropospheric solar signal. The 300 hPa geopotential height is used as the lower boundary in a middle atmosphere model which is run with a constant solar cycle minimum radiative forcing, so that only the lower boundary is forcing the middle atmosphere. The zonal wind and temperature at 300-0.01 hPa from the model experiment are studied in boreal winter for the same years that were studied in the geopotential height analysis. Differences of the means of the two data sets reproduce the structure and amplitude seen in observations and in reanalysis data. Whether this is a direct effect of the solar forcing of the troposphere or a feedback coupling of the solar forcing of the stratosphere is not presently clear, but the modulation of the tropospheric planetary waves seems to be important for the observed solar modulation of the stratosphere.

During the declining phase of the solar cycle 22, in June 1991, energetic flares were produced by active regions NOAA/USAF 6659. The associated solar proton events affected the earth environment. An evaluation of the solar activity during the first half of June 1991 was made, leading to a possible method for high energetic solar flares prediction. The method depend on cumulative summation curves of the H-alpha flares, and x-ray bursts, in the active region 6659 during the rotation when the energetic solar flares of June 1991 have occurred. It is shown that a steep trend of increased activity begins several tens of hours prior to the occurrence of the energetic flare.