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Sample records for 11-year solar cycle

  1. Influence of the 11-Year Solar Cycle on Variations of Cosmic Ray Intensity

    NASA Astrophysics Data System (ADS)

    Ma, L. H.; Han, Y. B.; Yin, Z. Q.

    2009-03-01

    The monthly cosmic ray intensity (CRI) time series from Climax, Huancayo, Moscow, Kiel, and Calgary are used to investigate the presence of the 11-year periodic component with special attention paid to the solar influence on these variations. The results show obvious 11-year temporal characteristics in CRI variations. We also find a close anticorrelation between the 11-year solar cycle and CRI variations and time delays of the CRI relative to solar activity.

  2. The relationship of air temperature variations over the northern hemisphere during the secular and 11-year solar cycles

    NASA Technical Reports Server (NTRS)

    Ryzhakov, L. Y.; Tomskaya, A. S.

    1978-01-01

    A comparison was made of air temperature anomaly maps for the months of January and July against a background of high and low secular solar activity, with and without regard for the 11 year cycle. By comparing temperature variations during the 11 year and secular cycles, it is found that the 11 year cycle influences thermal conditions more strongly than the secular cycle, and that temperature differences between extreme phases of the solar cycles are greater in January than in July.

  3. The 11 years solar cycle as the manifestation of the dark Universe

    SciTech Connect

    Zioutas, K.; Semertzidis, Y.; Tsagri, M.; Papaevangelou, T.; Hoffmann, D. H.H.; Anastassopoulos, V.

    2014-11-26

    Sun’s luminosity in the visible changes at the 10-3 level, following an 11 years period. In X-rays, which should not be there, the amplitude varies even ~105 times stronger, making their mysterious origin since the discovery in 1938 even more puzzling, and inspiring. We suggest that the multifaceted mysterious solar cycle is due to some kind of dark matter streams hitting the Sun. Planetary gravitational lensing enhances (occasionally) slow moving flows of dark constituents towards the Sun, giving rise to the periodic behaviour. Jupiter provides the driving oscillatory force, though its 11.8 years orbital period appears slightly decreased, just as 11 years, if the lensing impact of other planets is included. Then, the 11 years solar clock may help to decipher (overlooked) signatures from the dark sector in laboratory experiments or observations in space.

  4. The 11 years solar cycle as the manifestation of the dark Universe

    NASA Astrophysics Data System (ADS)

    Zioutas, K.; Tsagri, M.; Semertzidis, Y. K.; Papaevangelou, T.; Hoffmann, D. H. H.; Anastassopoulos, V.

    2014-11-01

    Sun's luminosity in the visible changes at the 10-3 level, following the 11 years period. This variation increases with energy, and in X-rays, which should not even be there, the amplitude varies up to 105 times stronger, making their mysterious origin since the discovery in 1938 even more puzzling, and inspiring. We suggest that the multifaceted mysterious solar cycle is due to some kind of dark matter streams hitting the Sun. Planetary gravitational lensing enhances (occasionally) slow moving flows of dark constituents toward the Sun, giving rise to the periodic behavior. Jupiter provides the driving oscillatory force, though its 11.8 years orbital period appears slightly decreased, just as 11 years, if the lensing impact of other planets is included. Then, the 11 years solar clock may help to decipher (overlooked) signatures from the dark sector in laboratory experiments or observations in space.

  5. The 11 years solar cycle as the manifestation of the dark Universe

    DOE PAGES

    Zioutas, K.; Semertzidis, Y.; Tsagri, M.; ...

    2014-11-26

    Sun’s luminosity in the visible changes at the 10-3 level, following an 11 years period. In X-rays, which should not be there, the amplitude varies even ~105 times stronger, making their mysterious origin since the discovery in 1938 even more puzzling, and inspiring. We suggest that the multifaceted mysterious solar cycle is due to some kind of dark matter streams hitting the Sun. Planetary gravitational lensing enhances (occasionally) slow moving flows of dark constituents towards the Sun, giving rise to the periodic behaviour. Jupiter provides the driving oscillatory force, though its 11.8 years orbital period appears slightly decreased, just asmore » 11 years, if the lensing impact of other planets is included. Then, the 11 years solar clock may help to decipher (overlooked) signatures from the dark sector in laboratory experiments or observations in space.« less

  6. The spatial distribution of the association between total ozone and the 11-year solar cycle

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; van Loon, H.

    1992-02-01

    The pattern of correlation between the 11-year solar cycle and heights and temperatures in the lower stratosphere is in all months shaped as a crescent with its axis in the subtropics. The change of total ozone from the solar maximum in 1979-1980 to the minimum in 1985-1986 has the same shape. Although the effect of the solar cycle is said to have been removed from the ozone data, two thirds of the stations which have been used for this purpose lie outside the regions where the stratosphere is significantly correlated with the solar cycle. For this reason it is unlikely that the influence of the cycle has been completely eliminated.

  7. Association between the 11-Year Solar Cycle and the Atmosphere. Part V: Summer.

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; van Loon, H.

    1992-03-01

    We describe a 10-12-year oscillation (abbreviated to TTO in the following) in the upper troposphere and lower stratosphere of the Northern Hemisphere in summer. The TTO has been presented since the time series began in 1951, and it has been in phase with the 11-year solar cycle during that time. The analyses show that the large amplitude of the TTO in the geopotential heights of the lower stratosphere is associated with temperature variations on the same time scale in the upper troposphere.

  8. On the ambiguous nature of the 11-year solar cycle signal profile in stratospheric ozone

    NASA Astrophysics Data System (ADS)

    Dhomse, Sandip; Chipperfield, Martyn; Damadeo, Robert; Zawodny, Joe; Ball, William; Feng, Wuhu; Hossaini, Ryan; Mann, Graham; Haigh, Joana

    2016-04-01

    We use three satellite datasets and simulations from a 3-D chemical transport model, forced by three different solar flux datasets, to diagnose the 11-year solar cycle signal (SCS) in stratospheric ozone. Our analysis shows that compared to SAGE II v6.2, a reduced upper stratospheric SCS in SAGE II v7.0 is due to a more realistic ozone-temperature anti-correlation. Overall, all model simulations show a positive SCS in the lower and middle stratosphere and negligible SCS in the upper stratosphere in agreement with SAGE v7.0, HALOE and MLS data. The model simulations show a differently structured SCS over different time periods covered by the satellite datasets, which helps to resolve some observed differences. However, despite the improvements to the SAGE II data, due to remaining biases in current observational and reanalysis datasets, accurate quantification of the influence of solar flux variability on the climate system remains an open scientific question.

  9. Using the 11-year Solar Cycle to Predict the Heliosheath Environment at Voyager 1 and 2

    NASA Astrophysics Data System (ADS)

    Michael, A.; Opher, M.; Provornikova, E.; Richardson, J. D.; Toth, G.

    2015-12-01

    As Voyager 2 moves further into the heliosheath, the region of subsonic solar wind plasma in between the termination shock and the heliopause, it has observed an increase of the magnetic field strength to large values, all while maintaining magnetic flux conservation. Dr. Burlaga will present these observations in the 2015 AGU Fall meeting (abstract ID: 59200). The increase in magnetic field strength could be a signature of Voyager 2 approaching the heliopause or, possibly, due to solar cycle effects. In this work we investigate the role the 11-year solar cycle variations as well as magnetic dissipation effects have on the heliosheath environments observed at Voyager 1 and 2 using a global 3D magnetohydrodynamic model of the heliosphere. We use time and latitude-dependent solar wind velocity and density inferred from SOHO/SWAN and IPS data and solar cycle variations of the magnetic field derived from 27-day averages of the field magnitude average of the magnetic field at 1 AU from the OMNI database as presented in Michael et al. (2015). Since the model has already accurately matched the flows and magnetic field strength at Voyager 2 until 93 AU, we extend the boundary conditions to model the heliosheath up until Voyager 2 reaches the heliopause. This work will help clarify if the magnetic field observed at Voyager 2 should increase or decrease due to the solar cycle. We describe the solar magnetic field both as a dipole, with the magnetic and rotational axes aligned, and as a monopole, with magnetic field aligned with the interstellar medium to reduce numerical reconnection within the heliosheath, due to the removal of the heliospheric surrent sheet, and at the solar wind - interstellar medium interface. A comparison of the models allows for a crude estimation of the role that magnetic dissipation plays in the system and whether it allows for a better understanding of the Voyager 2 location in the heliosheath.

  10. Hysteresis of indices of solar and ionospheric activity during 11-year cycles

    NASA Astrophysics Data System (ADS)

    Bruevich, E. A.; Kazachevskaya, T. V.; Katyushina, V. V.; Nusinov, A. A.; Yakunina, G. V.

    2016-12-01

    The effects of hysteresis, which is a manifestation of ambiguous relationships between different solar activity indices during the rising and declining phases of solar cycles, are analyzed. The paper addresses the indices characterizing radiation from the solar photosphere, chromosphere, and corona, and the ionospheric indices. The 21st, 22nd, and 23rd solar cycles, which significantly differ from each other in amplitude, exhibit different extents of hysteresis.

  11. Fluctuations of the Caspian Sea level in the quasi-two-year and 11-year cycles of solar activity

    SciTech Connect

    Nuzhdina, M.A.

    1995-07-01

    Fluctuations of the Caspian Sea level due to dynamics of solar activity in its quasi-two-year and 11-year cycles, as well as to the influence of the 22-to 23-year magnetic cycle are analyzed. Perturbation of the geomagnetic field and the atmospheric circulation are regarded as a transmitting mechanism of the Sun`s influence on the Earth`s hydrosphere.

  12. Luni-solar 18.6- and solar cycle 10 - 11-year signals in USA air temperature records.

    NASA Astrophysics Data System (ADS)

    Currie, R. G.

    1993-02-01

    Spectrum analysis of 1197 USA air temperature records yields evidence for two peaks with periods 18.8±1.7 and 10.4±0.5 years. Tests by the t-statistic show that both are significant at confidence levels of 99.9 per cent, and both account for 23 per cent of total variance in the raw data. They are identified as the luni-solar 18.6 year Mn and solar cycle Sc 10 - 11 year signals in climate, induced by the twelfth largest constituent tide acting on the Earth and a variation of 10 to 11 years in the Sun's luminosity of the order of 0.1 per cent. Amplitude and phase of Mn wavetrains are highly non-stationary with respect to both time and geography; in particular, abrupt 180° phase changes in wave polarity are often observed. Amplitude and phase of the Sc waves are also highly non-stationary.

  13. Climate variability related to the 11 year solar cycle as represented in different spectral solar irradiance reconstructions

    NASA Astrophysics Data System (ADS)

    Kruschke, Tim; Kunze, Markus; Misios, Stergios; Matthes, Katja; Langematz, Ulrike; Tourpali, Kleareti

    2016-04-01

    shortwave heating rate differences (additionally collated with line-by-line calculations using libradtran), differences in the photolysis rates, as well as atmospheric circulation features (temperature, zonal wind, geopotential height, etc.). It is shown that atmospheric responses to the different SSI datasets differ significantly from each other. This is a result from direct radiative effects as well as indirect effects induced by ozone feedbacks. Differences originating from using different SSI datasets for the same level of solar activity are in the same order of magnitude as those associated with the 11 year solar cycle within a specific dataset. However, the climate signals related to the solar cycle are quite comparable across datasets.

  14. The Antarctic ozone minimum - Relationship to odd nitrogen, odd chlorine, the final warming, and the 11-year solar cycle

    NASA Technical Reports Server (NTRS)

    Callis, L. B.; Natarajan, M.

    1986-01-01

    Photochemical calculations along 'diabatic trajectories' in the meridional phase are used to search for the cause of the dramatic springtime minimum in Antarctic column ozone. The results indicate that the minimum is principally due to catalytic destruction of ozone by high levels of total odd nitrogen. Calculations suggest that these levels of odd nitrogen are transported within the polar vortex and during the polar night from the middle to upper stratosphere and lower mesosphere to the lower stratosphere. The possibility that these levels are related to the 11-year solar cycle and are increased by enhanced formation in the thermosphere and mesosphere during solar maximum conditions is discussed.

  15. 11-year solar cycle in Schumann resonance data as observed in Antarctica

    NASA Astrophysics Data System (ADS)

    Nickolaenko, A. P.; Koloskov, A. V.; Hayakawa, M.; Yampolski, Yu. M.; Budanov, O. V.; Korepanov, V. E.

    2015-03-01

    Studies of Schumann resonance allows obtaining characteristics of the lower ionosphere and the dynamics of global thunderstorms based on the data recorded at a single or a few ground-based observatories. We use the simple model of a point source. The vertical profile of air conductivity is described by the "knee" model. We used continuous Schumann resonance record from the "Akademik Vernadsky" Ukrainian Antarctic station (geographic coordinates: 65.25S and 64.25W, L=2.6). A data processing show that the north-south seasonal drift of global thunderstorms was about 20°, and the intensity of global lightning activity changed annually by the factor 1.5-2. Unequal duration of the "electromagnetic" seasons was confirmed ("summer" ~ 120 days, "winter" ~ 60 days; duration of the "spring" is shorter than the "fall"). A possible explanation of inter-annual variations of Schumann resonance parameter follows from changes in the effective height of the lower ionosphere. In this case, we used the spatial thunderstorm distribution following from the annual data of the Optical Transient Detector satellite. We show that recorded inter-annual variations of resonance frequencies and intensities might be attributed to 1-2 km alterations in the knee height of ionosphere. The most realistic mechanism of changes should include both the height variations and the drift of global thunderstorms. Both the processes are governed by solar activity. We also estimated the feasible trend in the equatorial soil surface temperature by 1.6° C corresponding to the inter-annual change of Schumann resonance intensity.

  16. Relationship between phases of quasi-decadal oscillations of total ozone and the 11-year solar cycle

    NASA Astrophysics Data System (ADS)

    Visheratin, K. N.

    2012-02-01

    Temporal variability of the relationship between the phases of quasi-decadal oscillations (QDOs) of total ozone (TO), measured at the Arosa station, and the Ri international sunspot number have been analyzed for the period of 1932-2009. Before the 1970s, the maximum phase of ozone QDOs lagged behind solar activity variations by about 2.5-2.8 years and later outstripped by about 1.5 years. We assumed that the TO QDOs in midlatitudes of the Northern Hemisphere were close to being in resonance with solar activity oscillations in the period from the mid-1960s to the mid-1970s and assessed the characteristic delay period of TO QDOs. The global distribution of phases and amplitudes of TO QDOs have been studied for the period from 1979 to 2008 based on satellite data. The maximum phase of TO QDOs first onsets in northern middle and high latitudes and coincides with the end of the growth phase of the 11-year solar cycle. In the tropics, the maximum oscillation phase lags behind by 0.5-1 year. The maximum phase lag near 40-50° S is about two years. The latitudinal variations of the phase of TO QDOs have been approximated.

  17. 11 -year planetary index of solar activity

    NASA Astrophysics Data System (ADS)

    Okhlopkov, Victor

    In papers [1,2] introduced me parameter - the average difference between the heliocentric longitudes of planets ( ADL ) , which was used for comparison with solar activity. The best connection of solar activity ( Wolf numbers used ) was obtained for the three planets - Venus, Earth and Jupiter. In [1,2] has been allocated envelope curve of the minimum values ADL which has a main periodicity for 22 years and describes well the alternating series of solar activity , which also has a major periodicity of 22. It was shown that the minimum values of the envelope curve extremes ADL planets Venus, Earth and Jupiter are well matched with the 11- year solar activity cycle In these extremes observed linear configuration of the planets Venus, Earth and Jupiter both in their location on one side of the Sun ( conjunctions ) and at the location on the opposite side of the Sun ( three configurations ) This work is a continuation of the above-mentioned , and here for minimum ADL ( planets are in conjunction ) , as well as on the minimum deviation of the planets from a line drawn through them and Sun at the location of the planets on opposite sides of the Sun , compiled index (denoted for brevity as JEV ) that uniquely describes the 11- year solar cycle A comparison of the index JEV with solar activity during the time interval from 1000 to 2013 conducted. For the period from 1000 to 1699 used the Schove series of solar activity and the number of Wolf (1700 - 2013 ) During the time interval from 1000 to 2013 and the main periodicity of the solar activity and the index ADL is 11.07 years. 1. Okhlopkov V.P. Cycles of Solar Activity and the Configurations of Planets // Moscow University Physics Bulletin, 2012 , Vol. 67 , No. 4 , pp. 377-383 http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.3103/S0027134912040108. 2 Okhlopkov VP, Relationship of Solar Activity Cycles to Planetary Configurations // Bulletin of the Russian Academy of Sciences. Physics, 2013 , Vol. 77 , No. 5

  18. Altitude dependent sensitivity of equatorial atomic oxygen in the MLT region to the quasi-11-year and quasi-27-day solar cycles

    NASA Astrophysics Data System (ADS)

    Lednyts'kyy, Olexandr; Von Savigny, Christian

    2016-07-01

    We retrieved atomic oxygen concentration ([O]) profiles with help of volume emission rate (VER) profiles calculated from the measured by SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) emissions of green line nightglow in the MLT (Mesosphere/Lower Thermosphere) region. We quantified the sensitivity of equatorial [O] to the 11-year and 27-day solar cycle forcing represented by such proxy indicators of solar activity as MgII index and Lyman-α with help of the wavelet, cross-correlation, superposed epoch, regression and harmonical analysis methods. We applied ordinary least squares bisector fitting on MgII index and F10.7 radio flux, which is measured in solar flux units (sfu), to convert the [O] sensitivity values in sfu and finally in percent changes. The same procedure was performed in the case of Lyman-α. Our results of the sensitivity analysis correspond well to the 11-year solar cycle response of O volume mixing ratios found in simulations performed with the WACCM3 (Whole Atmosphere Community Climate Model, v. 3) and the HAMMONIA (3D Hamburg Model of the Neutral and Ionized Atmosphere) model. We identified an 11-year solar cycle variation, quasi-biennial and annual/semi-annual oscillations as well as signatures of the 27-day cycle of solar activity as presented in the MLT O layer. The most remarkable result is that the found sensitivities agree within their uncertainties and do not depend on averaging method (annual, monthly and daily) of the [O] time series. We report on 11-year and 27-day solar cycle signatures in dependence on altitude intervals used to average the [O] time series.

  19. Chemical-dynamical response to the 11-year solar cycle in a transient CCM simulation of the past

    NASA Astrophysics Data System (ADS)

    Kubin, A.; Langematz, U.; Baumgärtner, A.; Brühl, Ch.

    2009-04-01

    We present results from a CCMVal REF1 simulation performed with the ECHAM5/MESSy model system. The time period 1960 to 2000 was simulated using the model in T42L90 resolution. The model was forced by observed sea surface temperatures and spectrally resolved solar irradiances as well as greenhouse gases and ozone depleting substances according to the CCMVal recommendations. The QBO was internally generated and major volcanic eruptions were included. A state-of-the-art multiple linear regression model is used for the analysis. Emphasis is laid on the 11-year solar signal in chemical and dynamical variables such as ozone volume mixing ratio and related radiative heating, temperature and zonal wind. Moreover, the solar impact on planetary wave propagation and the residual circulation is examined as well as the transfer of the solar signal from the stratosphere to the troposphere. The solar influence on variability patterns as the Arctic Oscillation or the North Atlantic Oscillation is studied and we investigate furthermore the impact on tropical precipitation. The results are compared with observations.

  20. Harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, N.

    2012-12-01

    We show that the Schwabe frequency band of the Zurich sunspot record since 1749 is made of three major cycles that are closely related to the spring tidal period of Jupiter and Saturn (~9.93 year), to the tidal sidereal period of Jupiter (about 11.86 years) and to a central cycle that may be associated to a quasi-11-year solar dynamo cycle. The central harmonic is approximately synchronized to the average of the two planetary frequencies. A harmonic model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals major beat periods occurring at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. Equivalent synchronized cycles are found in cosmogenic solar proxy records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial three-frequency beat cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima around 1900-1920 and 1960-1980, the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005, and a secular upward trending during the 20th century. The latter modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature modulation since 1850. The model forecasts a new prolonged solar minimum during 2020-2045, which is produced by the minima of both the 61 and 115-year reconstructed cycles. Finally, the model predicts

  1. Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola

    2012-05-01

    The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle may be associated to a quasi-11-year solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Spörer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial three-frequency beat cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900-1920 and 1960-1980 and the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature

  2. 11-year cycle solar modulation of cosmic ray intensity inferred from C-14 content variation in dated tree rings

    NASA Technical Reports Server (NTRS)

    Fan, C. Y.; Chen, T. M.; Yun, S. X.; Dai, K. M.

    1983-01-01

    A liquid scintillation-photomultiplier tube counter system was used to measure the Delta-C-14 values of 60 tree rings, dating from 1866 to 1925, that were taken from a white spruce grown in Canada at 68 deg N, 130 deg W. A 10-percent variation is found which is anticorrelated with sunspot numbers, although the amplitude of the variation is 2-3 times higher than expected in trees grown at lower latitudes. A large dip in the data at about 1875 suggests an anomalously large modulation of cosmic ray intensity during the 1867-1878 AD solar cycle, which was the most active of the 19th century.

  3. Middle Atmosphere Response to Different Descriptions of the 11-Year Solar Cycle in Spectral Irradiance in a Chemistry-Climate Model

    NASA Technical Reports Server (NTRS)

    Swartz, W. H.; Stolarski, R. S.; Oman, L. D.; Fleming, E. L.; Jackman, C. H.

    2012-01-01

    The 11-year solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response 50 using the SORCE SSI is nearly 2 K per 100 units 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the

  4. January-february Tropospheric Climate for the Northern Hemisphere and the 11-year Solar Cycle, the QBO and the Southern Oscillation

    NASA Technical Reports Server (NTRS)

    Barnston, Anthony G.; Livezey, Robert E.

    1990-01-01

    Examined here is a recently discovered association between the 11-year solar cycle and the atmosphere that is most easily detectable when the two phases of the Quasi-biennial Oscillation (QBO) are considered individually rather than pooled. The influence of the Southern Oscillation (SO) for either of the two QBO phases is then combined with that of the solar cycle in the form of two-predictor multiple regression. The strong and well-defined relationship between the 11-year 10.7 cm solar flux cycle and the lower troposphere Northern Hemisphere January-February climate for QBO phase-stratified samples (van Loon and Labitzke 1988, Barnston and Livezey 1989) failed for the west QBO phase in 1989. Here, the opposing 1989 event is explained, at least in part, on the basis of the phase of the SO (the cold tropical Pacific SST event of 1988 to 1989). It is demonstrated that both the SO and the solar flux have moderate and quasi-independent correlations with the climate over certain regions, and where there is strong overlap they can work either in harmony or in opposition. In 1989 in North America the influences of the SO and the flux conflicted to an unprecedented extent, and the SO was the controlling influence in most regions of the continent (western Canada being one exception). The 1989 event draws attention to the smallness of the QBO phase-stratified samples and the still more serious holes in the two-dimensional sample space of flux and SO when both factors are viewed as predictors within one QBO phase.

  5. Decadal variability of upper ocean heat content in the Pacific: Responding to the 11-year solar cycle

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Yan, Shuangxi; Qiao, Fangli

    2015-12-01

    Ocean heat content anomaly (OHCa) time series in some areas of the Pacific are significantly correlated with the total solar irradiance (TSI). Using the composite mean-difference method, we determined the mean response of OHCa in the upper-700 m of the ocean to the TSI. Among the high solar response areas, we figure out two regions, one in the tropical mid-Pacific and the other in the western Pacific, where the OHCa present decadal variations, but different phases. The variation in phase of the solar response indicates that there exists an agency for the OHCa's response to TSI.

  6. Structure of the Heliotail from Interstellar Boundary Explorer Observations: Implications for the 11-year Solar Cycle and Pickup Ions in the Heliosheath

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; Funsten, H. O.; McComas, D. J.; Reisenfeld, D. B.; Schwadron, N. A.

    2017-02-01

    Interstellar Boundary Explorer (IBEX) measurements of energetic neutral atoms (ENAs) from the heliotail show a multi-lobe structure of ENA fluxes as a function of energy between ∼0.71 and 4.29 keV. Below ∼2 keV, there is a single structure of enhanced ENA fluxes centered near the downwind direction. Above ∼2 keV, this structure separates into two lobes, one north and one south of the solar equatorial plane. ENA flux from these two lobes can be interpreted as originating from the fast solar wind (SW) propagating through the inner heliosheath (IHS). Alternatively, a recently published model of the heliosphere suggests that the heliotail may split into a “croissant-like” shape, and that such a geometry could be responsible for the heliotail ENA feature. Here we present results from a time-dependent simulation of the heliosphere that produces a comet-like heliotail, and show that the 11-year solar cycle leads to the formation of ENA lobes with properties remarkably similar to those observed by IBEX. The ENA energy at which the north and south lobes appear suggests that the pickup ion (PUI) temperature in the slow SW of the IHS is ∼107 K. Moreover, we demonstrate that the extinction of PUIs by charge-exchange is an essential process required to create the observed global ENA structure. While the shape and locations of the ENA lobes as a function of energy are well reproduced by PUIs that cross the termination shock, the results appear to be sensitive to the form of the distribution of PUIs injected in the IHS.

  7. The possible mechanism of the "stratospheric bridge" modulation by the Pacific Decadal Oscillation in early winter and the QBO, 11-year solar cycle in late winter

    NASA Astrophysics Data System (ADS)

    Jadin, Evgeny; Wei, Ke; Chen, Wen; Wang, Lin

    Questions of the interannual variations of the extra-tropical stratospheric dynamics, its rela-tionship with the sea surface temperature (SST) anomalies in the North Pacific (Pacific Decadal Oscillation -PDO) in early winter (November-December), Quasi-Biennial Oscillation (QBO) (Holton-Tan relations), a decadal modulation by the 11-year Solar Cycle (SC) (Labitzke, van Loon -LvL correlations) in late winter (January-February) are discussed. In early winter, the interannual changes of the planetary wave activity define partly the variations of the strato-spheric circulation in subsequent January [Zyulyaeva and Jadin, 2009]. The interannual and decadal variations of the stratospheric wave activity appear to be associated with those of the PDO [Jadin et al. 2009]. A decadal period from the mid-1970s to mid-1990s of the violation of the Holton-Tan (HT) relationship corresponds well to that of the positive PDO phase (anoma-lously cold SSTs in the central North Pacific). Using the NCEP and ERA-40 monthly mean reanalysis datasets, the three-dimensional Eliassen-Palm fluxes are calculated. The results of the analysis of relations between the upward/downward propagation of planetary waves in the lower stratosphere ("stratospheric bridge"), their interaction with the zonal wind and the HT and LvL correlations for January-February are presented. In contrast with early winter, the large role in the wave-zonal flow interaction plays the downward propagation of planetary waves from the stratosphere to the troposphere over Canada and North Atlantic ("stratospheric wave hole") responsible for the sink of the eddy energy from the stratosphere. One can suggest that there are two dominant regimes in the stratosphere-troposphere coupling in late winter: 1) the "ventilation regime" with the strong penetration of planetary waves from the troposphere over north Eurasia and their strong downward propagation over Canada and North Atlantic, and 2) the "blocking regime" with the weak those

  8. Analysis of the sensitivity of the composition and temperature of the stratosphere to the variability of spectral solar radiation fluxes induced by the 11-year cycle of solar activity

    NASA Astrophysics Data System (ADS)

    Smyshlyaev, S. P.; Galin, V. Ya.; Blakitnaya, P. A.; Lemishchenko, A. K.

    2016-01-01

    The sensitivity of the gas composition of the atmosphere and its temperature to the changes in spectral radiation fluxes during the 11-year cycle of solar activity has been analyzed with a chemistry-climate model of the lower and middle atmosphere. For this, the data of satellite measurements acquired in the first decade of the 21st century were used. The results of the model calculations showed that, in addition to the increase in the spectral flux in the absorption bands of molecular oxygen that leads to the growth of the ozone content, the changes in the flux at longer wavelengths are significant for the composition and temperature of the atmosphere. The changes of the ozone destruction rate in different catalytic cycles partly compensate each other; in these processes, the destruction rate increases in the reaction with atomic oxygen, while it decreases in the hydrogen and chlorine cycles.

  9. Hindcast and forecast of grand solar minina and maxima using a three-frequency dynamo model based on Jupiter-Saturn tidal frequencies modulating the 11-year sunspot cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola

    2016-04-01

    The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The two side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle can be associated to a quasi-11-year sunspot solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. These frequencies and other oscillations appear once the model is non-linearly processed. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900- 1920 and 1960-1980 and the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with

  10. Cosmic Ray 11-Year Modulation for Sunspot Cycle 24

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.; Ygbuhay, R. C.

    2015-02-01

    Galactic cosmic-ray (GCR) modulation at 1 AU for sunspot (SSN) Cycle 24 is studied using data from a global network of detectors and balloon measurements of low-energy ions at high latitudes in Russia. The observed modulation is modest compared with previous cycles. The tilt angle of the heliospheric current sheet reached a maximum value for Cycle 24 even though the peak of the interplanetary magnetic-field intensity at 1 AU has a much lower value (≈ 5 nT). The solar polar field in the northern hemisphere reversed in June 2012 and again in March 2014 while that in the southern hemisphere reversed in July 2013. The double field reversal in northern hemisphere after SSN maximum is not expected from dynamo theory. GCR modulation is at maximum phase in 2013. We have also studied the anomalous GCR recovery in 2009 using data from a low-energy proton channel on Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA). The rigidity dependence of the Cycle 24 modulation is computed using data from neutron monitors, directional muon telescopes at Nagoya, Japan, and detectors on balloons at high latitudes in Russia. It is a power law with an exponent -1.29, similar to previous solar cycles (-1.2±0.1); the nearly linear dependence of the modulation on the rigidity over a wide range poses a challenge to the quasi-linear theory (QLT) of GCR modulation.

  11. Coupling of the Matched Gravity and Electromagnetic Fields of the Sun with Jupiter and its Moons Together in Nearest Portion of Jupiter's Orbit to the Sun as the Main Cause of the Peak of Approximately 11 Yearly Solar Cycles and Hazards from Solar Storms

    NASA Astrophysics Data System (ADS)

    Gholibeigian, Kazem; Gholibeigian, Hassan

    2016-04-01

    On March 13, 1989 the entire province of Quebec Blackout by solar storm during solar cycle 22. The solar storm of 1859, also known as the Carrington event, was a powerful geomagnetic solar storm during solar cycle 10. The solar storm of 2012 during solar cycle 24 was of similar magnitude, but it passed Earth's orbit without striking the plane. All of these solar storms occurred in the peak of 11 yearly solar cycles. In this way, the White House in its project which is focusing on hazards from solar system, in a new strategy and action plan to increase protection from damaging solar emissions, should focus on coupling of the matched Gravity and Electromagnetic Fields)GEFs) of the Sun with Jupiter and its moons together. On the other hand, in solar system, the Jupiter's gravity has largest effect to the Sun's core and its dislocation, because the gravity force between the Jupiter and the Sun is 11.834 times, In addition overlapping of the solar cycles with the Jupiter's orbit period is 11.856 years. These observable factors lead us to the effect of the Jupiter and Sun gravity fields coupling as the main cause of the approximately 11 years duration for solar cycles. Its peak in each cycle is when the Jupiter is in nearest portion to the Sun in its orbit. In this way, the other planets in their coupling with Sun help to the variations and strengthening solar cycles. [Gholibeigian, 7/24/2015http://adsabs.harvard.edu/abs/2014EGU]. In other words, the both matched GEFs are generating by the large scale forced convection system inside the stars and planets [Gholibeigian et. al, AGU Fall Meeting 2015]. These two fields are couple and strengthening each other. The Jupiter with its 67 moons generate the largest coupled and matched GEFs in its core and consequently strongest effect on the Sun's core. Generation and coupling of the Jupiter's GEFs with its moons like Europa, Io and Ganymede make this planet of thousands of times brighter and many times bigger than Earth as the

  12. The effect of the 11-year solar-cycle on the temperature in the upper-stratosphere and mesosphere: Part II numerical simulations and the role of planetary waves

    NASA Astrophysics Data System (ADS)

    Hampson, J.; Keckhut, P.; Hauchecorne, A.; Chanin, M. L.

    2005-07-01

    Results from mechanistic model simulations have been analysed to examine the effect of the solar cycle, and in particular how the level of planetary wave activity changes the effect of the solar cycle. The model is a stratosphere and mesosphere model with detailed chemical, radiative and dynamical schemes. Planetary waves are initiated at the lowest boundary level of the model, which corresponds to the tropopause height. Model simulations have been carried out in pairs, with one simulation using solar forcing corresponding to solar minimum and the other to solar maximum. The level of lower boundary planetary wave forcing is varied between pairs of model simulations. The difference in temperature signal between the pairs of simulations is presented. The results illustrate the crucial role played by the planetary wave forcing in the solar cycle temperature signal. The solar cycle temperature signal in the tropics and subtropics is about 1 K for all values of wave forcing. However, in the extra-tropics the solar signal varies critically with wave forcing, giving a solar signal as strong as 16 K for intermediate values of wave forcing. Despite some spatial differences, the simulations with a specific wave forcing show good qualitative agreements with observational results presented in the companion paper [Keckhut et al., 2005. Journal of Atmospheric and Solar-Terrestrial Physics, submitted for publication]. Above a critical level of wave activity, the non-linear interaction with the mean flow induces a stratospheric warming and a strong temperature change. The critical wave-forcing amplitude necessary to produce such an event is very sensitive to the initial state of the atmosphere and a small change of the mean wind, due for example to an enhancement of the solar forcing, can generate a large difference in temperature, depending on the level of the wave forcing. The numerical simulations presented here suggest a mechanism by which a small change induced by the solar

  13. The Solar Cycle.

    PubMed

    Hathaway, David H

    The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

  14. The Solar Cycle

    NASA Astrophysics Data System (ADS)

    Hathaway, David H.

    2015-12-01

    The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

  15. The Signal of the 11-Year Sunspot Cycle in the Upper Troposphere-Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; van Loon, H.

    1997-05-01

    The paper summarizes work by the authors over the past ten years on an apparent signal of the 11-year sunspot cycle in the lower stratosphere-upper troposphere. The signal appears as a basic, consistent pattern in correlations between heights of stratospheric constant-pressure levels, at least as high as 25 km, and the solar cycle in which the highest correlations are in the subtropics. The variation of the stratospheric heights in phase with the sunspot cycle are - in the areas of high correlations between the two - associated with temperature variations on the same time scale in the middle and upper troposphere. The spatial distribution of the correlations suggests that the year-to-year changes in tropical and subtropical vertical motions contain a component on the time scale of the solar cycle. In January and February the correlations with the sunspot cycle are smallest. The smallness of the correlations is owing to the fact that they are different in the east and west years of the quasi-biennial oscillation in the equatorial stratospheric winds. The correlation pattern in the east years is the same as in the other seasons and is statistically significant. In the west years the correlations are insignificant outside the arctic, and the positive correlation in the arctic in these years is related to the fact that major midwinter breakdowns of the cyclonic vortex in the west years so far have happened only at maxima in the solar cycle. Until recently reliable continuous series of analyses of the stratosphere were not available for the southern hemisphere. The U.S. National Centers for Environmental Prediction and the National Center for Atmospheric Research have now, however, issued a 23-year series of re-analyzed global data which has made it possible to detect the solar signal on the southern hemisphere. It turns out to be almost the same as that on the northern hemisphere. The correlations between total column ozone and the sunspot cycle are lowest in the

  16. Relations of latitudinal characteristics of sunspot groups to the 11-year cycle amplitude at different phases

    NASA Astrophysics Data System (ADS)

    Miletskii, E. V.; Ivanov, V. G.

    2016-12-01

    Using sunspot data for cycles 12 to 23, we have investigated relations of some latitude characteristics of sunspot groups to the 11-year cycle amplitude at different phases. We have revealed a high correlation (with correlation coefficients >0.9) between the middle latitude of sunspot groups at phases of rise, maximum, and decay, on the one hand, and the amplitude of the corresponding cycle, on the other hand. We have shown that the maxima of the velocity of the motion of the sunspot formation zone to the equator have a special physical meaning: the rise phase of the 11-year cycle is characterized by significant correlations between the cycle amplitude and the maximum for the lowest boundary, and the cycle decay phase is characterized by the same maximum for the highest boundary. We have built equations allowing one to determine the amplitude of the 11-year cycle on the basis of data on the given latitudinal characteristics of sunspots groups.

  17. The 11-year solar radiation rhythm and the North Atlantic Oscillation during the last two centuries

    NASA Astrophysics Data System (ADS)

    Brunck, Heiko; Sirocko, Frank

    2016-04-01

    The study is based on a historical chronology of freezing events in central Europe during the last 230 years (river Rhine (Sirocko et al. 2012), Baltic Sea (Koslowski and Glaser, 1999) and Lake Constance (Dobras, 1983)). These regions display both significant similarities with extremely cold winters in central Germany for the years 1799, 1830, 1895, 1929, 1940, 1942, 1947, 1956 and 1963, as well as regional differences in timing and severity of cold winters. The statistical analysis of all 92 historical freezing events showed that 80 events occurred during a negative NAOwinter phase. The bootstrap test defined the results as extremely significant. To understand the climatic forcing behind the freezing chronology the NAO data set was smoothed by a three point running mean filter and compared with the 11- year cyclicity of the sunspot numbers. A complete NAO cycle can be observed within each solar cycle back to 1960 and from 1820 to 1900. From 1900 to 1960 the correlation between the Sun and NAO was weak. This on/off mode becomes visible only in the smoothed NAO data, when time intervals longer than "normal" weather observations are analysed. Statistical test for the coherence of the entire 230 years are insignificant. However, the relation is highly significant, if only the intervals from 1960 to 2010 and 1830 to 1900 are analysed. The phase correlation can be explained by temperature variations up to +-2.5°C in time series of stratospheric air temperature at 40 km height, where ozone is formed by ultraviolet solar radiation. Advanced analysis of sea surface temperatures from reanalysis data (ECMWF Data Archiv, 2013) between 30° - 40°N and 65° - 75°N indicate similar temperature variations in phase with the solar activity. Consequently, the 11 year solar periodicity is related to various parts of the Earth/Ocean/Atmosphere system and not only to the stratospheric signal. However, the NAO is the dominating mediator to implement a solar component into the

  18. Active longitudes in the period of overlap of 11-year cycles

    NASA Astrophysics Data System (ADS)

    Kramynin, A. P.; Mikhalina, F. A.

    2016-12-01

    It is shown that "active longitudes" for the sunspots of old and new cycles manifest themselves approximately in the same longitudinal intervals and remain for several 11-year cycles. To be more accurate, they vanish in some cycles but then appear again at the same longitudinal intervals in the other cycles. The entire period is characterized by a total of four active longitudes. The old-cycle sunspots observed at low equatorial latitudes in the Northern and Southern Hemispheres are characterized by a shift by ≈180°, which indicates antipodality of the active longitudes in the Northern and Southern Hemispheres. In the case of highlatitude sunspots (new-cycle sunspots), the best correlation is observed for the shift of ≈90°. There is supposedly a dependence of the rotation speed of active longitudes on the secular cycle.

  19. Difference between even and odd 11-year cycles in cosmic ray intensity

    NASA Technical Reports Server (NTRS)

    Otaola, J. A.; Perez-Enriquez, R.; Valdes-Galicia, J. F.

    1985-01-01

    Cosmic ray data for the period 1946-1984 are used to determine the run of the cosmic ray intensity over three complete solar cycles. The analysis shows a tendency towards a regular alternation of cosmic ray intensity cycles with double and single maxima. Whereas a saddle-like shape is characteristic of even cycles, odd cycles are characterized by a peak-like shape. The importance of this behavior is discussed in terms of different processes influencing cosmic ray transport in the heliosphere.

  20. On dependence of seismic activity on 11 year variations in solar activity and/or cosmic rays

    NASA Astrophysics Data System (ADS)

    Zhantayev, Zhumabek; Khachikyan, Galina; Breusov, Nikolay

    2014-05-01

    It is found in the last decades that seismic activity of the Earth has a tendency to increase with decreasing solar activity (increasing cosmic rays). A good example of this effect may be the growing number of catastrophic earthquakes in the recent rather long solar minimum. Such results support idea on existence a solar-lithosphere relationship which, no doubts, is a part of total pattern of solar-terrestrial relationships. The physical mechanism of solar-terrestrial relationships is not developed yet. It is believed at present that one of the main contenders for such mechanism may be the global electric circuit (GEC) - vertical current loops, piercing and electrodynamically coupling all geospheres. It is also believed, that the upper boundary of the GEC is located at the magnetopause, where magnetic field of the solar wind reconnects with the geomagnetic field, that results in penetrating solar wind energy into the earth's environment. The effectiveness of the GEC operation depends on intensity of cosmic rays (CR), which ionize the air in the middle atmosphere and provide its conductivity. In connection with the foregoing, it can be expected: i) quantitatively, an increasing seismic activity from solar maximum to solar minimum may be in the same range as increasing CR flux; and ii) in those regions of the globe, where the crust is shipped by the magnetic field lines with number L= ~ 2.0, which are populated by anomalous cosmic rays (ACR), the relationship of seismic activity with variations in solar activity will be manifested most clearly, since there is a pronounced dependence of ACR on solar activity variations. Checking an assumption (i) with data of the global seismological catalog of the NEIC, USGS for 1973-2010, it was found that yearly number of earthquake with magnitude M≥4.5 varies into the 11 year solar cycle in a quantitative range of about 7-8% increasing to solar minimum, that qualitatively and quantitatively as well is in agreement with the

  1. Cyclicity of Suicides May Be Modulated by Internal or External - 11-Year Cycles: An Example of Suicide Rates in Finland

    NASA Astrophysics Data System (ADS)

    Dimitrov, B. D.; Atanassova, P. A.; Rachkova, M. I.

    2009-12-01

    Multicomponent cyclicity in monthly suicides (periods T = 18, 46 and 198 months) was found and close similarity with heliogeophysical activity (HGA) suggested by Dimitrov in 1999. The current report aimed at scrutinizing the results on suicide annual cyclicity (seasonality) in Slovenia as reported by Oravecz et al in 2007 as well as at analyzing suicide data from Finland in this regard. We postulated that: (i) trans-year (12-24 months) or far-trans-year long-term cycles of suicides might interfere with their seasonality; and (ii) associations to environmental factors with alike cyclicity (e.g. HGA, temperature) could exist. Annual suicide incidence from Oulu, Finland over years 1987-1999 was analyzed. Annual data on solar activity (sunspot index Rz or Wolf number), planetary geomagnetic activity (aa-index) and local daily mean temperatures were used. The exploration of underlying chronomes (time structures) was done by periodogram regression analysis with trigonometric approximation. We analyzed temporal dynamics, revealed cyclicity, decomposed and reconstructed significant cycles and correlated the time series data. Suicide seasonality in Slovenia during the years 1971-2002 (n=384 months, peak May-June) was considered and, although some discrepancies and methodological weaknesses were suspected, we further hypothesized about trans-year and/or longer (far-transyear) cyclic components. Suicide incidence data from Finland indicated that the 12.5-year cyclic component (or trend) was almost parallel (coherent) to the cyclic heliogeophysical parameters and similar to local decreasing temperature dynamics. Also, 8-year and 24.5-year cycles were revealed. A correlation between the 12.5-year suicide cycle and 11-year solar cycle was found (R=0.919, p=0.000009). Above findings on cyclicity and temporal correlations of suicides with cyclic environmental factors, even being still preliminary, might not only allow for further more specific analyses. They might also corroborate

  2. Solar cycle changes in the polar solar wind

    NASA Technical Reports Server (NTRS)

    Coles, W. A.; Rickett, B. J.; Rumsey, V. H.; Kaufman, J. J.; Turley, D. G.; Ananthakrishnan, S.; Armstrong, J. W.; Harmons, J. K.; Scott, S. L.; Sime, D. G.

    1980-01-01

    It is noted that although the 11 year solar cycle was first recognized in 1843, it is still only poorly understood. Further, while there are satisfactory models for the magnetic variations, the underlying physics is still obscure. New observations on the changing three-dimensional form of the solar wind are presented which help relate some of the modulations observed in geomagnetic activity, the ionosphere, and the flux of galactic cosmic rays.

  3. Solar Cycle Predictions

    NASA Technical Reports Server (NTRS)

    Pesnell, William Dean

    2012-01-01

    Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as you consume the reduced propellant load more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations how those predictions could be made more accurate in the future will be discussed.

  4. Solar Cycle Prediction.

    PubMed

    Petrovay, Kristóf

    A review of solar cycle prediction methods and their performance is given, including forecasts for cycle 24. The review focuses on those aspects of the solar cycle prediction problem that have a bearing on dynamo theory. The scope of the review is further restricted to the issue of predicting the amplitude (and optionally the epoch) of an upcoming solar maximum no later than right after the start of the given cycle. Prediction methods form three main groups. Precursor methods rely on the value of some measure of solar activity or magnetism at a specified time to predict the amplitude of the following solar maximum. Their implicit assumption is that each numbered solar cycle is a consistent unit in itself, while solar activity seems to consist of a series of much less tightly intercorrelated individual cycles. Extrapolation methods, in contrast, are based on the premise that the physical process giving rise to the sunspot number record is statistically homogeneous, i.e., the mathematical regularities underlying its variations are the same at any point of time and, therefore, it lends itself to analysis and forecasting by time series methods. Finally, instead of an analysis of observational data alone, model based predictions use physically (more or less) consistent dynamo models in their attempts to predict solar activity. In their overall performance during the course of the last few solar cycles, precursor methods have clearly been superior to extrapolation methods. Nevertheless, most precursor methods overpredicted cycle 23, while some extrapolation methods may still be worth further study. Model based forecasts have not yet had a chance to prove their skills. One method that has yielded predictions consistently in the right range during the past few solar cycles is that of K. Schatten et al., whose approach is mainly based on the polar field precursor. The incipient cycle 24 will probably mark the end of the Modern Maximum, with the Sun switching to a state of

  5. Solar cycle modulation of Southern Annular Mode

    NASA Astrophysics Data System (ADS)

    Kuroda, Yuhji

    2016-04-01

    Climate is known to be affected by various factors, including oceanic changes and volcanic eruptions. 11-year solar cycle change is one of such important factors. Observational analysis shows that the winter-mean North Atlantic Oscillation (NAO) and late-winter/spring Southern Annular Mode (SAM) show structural modulation associated with 11-year solar cycle. In fact, these signals tend to extend from surface to upper stratosphere and persistent longer period only in the High Solar (HS) years. In the present study, we used 35-year record of ERA-Interim reanalysis data and performed wave-energy and momentum analysis on the solar-cycle modulation of the SAM to examine key factors to create such solar-SAM relationship. It is found that enhanced wave-mean flow interaction tends to take place in the middle stratosphere in association with enhanced energy input from diabatic heating on September only in HS years. The result suggests atmospheric and solar conditions on September are keys to create solar-SAM relationship.

  6. Predicting Solar Cycle 24 and beyond

    NASA Astrophysics Data System (ADS)

    Clilverd, Mark A.; Clarke, Ellen; Ulich, Thomas; Rishbeth, Henry; Jarvis, Martin J.

    2006-09-01

    We use a model for sunspot number using low-frequency solar oscillations, with periods 22, 53, 88, 106, 213, and 420 years modulating the 11-year Schwabe cycle, to predict the peak sunspot number of cycle 24 and for future cycles, including the period around 2100 A.D. We extend the earlier work of Damon and Jirikowic (1992) by adding a further long-period component of 420 years. Typically, the standard deviation between the model and the peak sunspot number in each solar cycle from 1750 to 1970 is +/-34. The peak sunspot prediction for cycles 21, 22, and 23 agree with the observed sunspot activity levels within the error estimate. Our peak sunspot prediction for cycle 24 is significantly smaller than cycle 23, with peak sunspot numbers predicted to be 42 +/- 34. These predictions suggest that a period of quiet solar activity is expected, lasting until ~2030, with less disruption to satellite orbits, satellite lifetimes, and power distribution grids and lower risk of spacecraft failures and radiation dose to astronauts. Our model also predicts a recovery during the middle of the century to more typical solar activity cycles with peak sunspot numbers around 120. Eventually, the superposition of the minimum phase of the 105- and 420-year cycles just after 2100 leads to another period of significantly quieter solar conditions. This lends some support to the prediction of low solar activity in 2100 made by Clilverd et al. (2003).

  7. A New Component of Solar Dynamics: North-South Diverging Flows Migrating toward the Equator with an 11 Year Period

    NASA Technical Reports Server (NTRS)

    Beck, J. G.; Gizon, L.; Duvall, Thomas L., Jr.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    Time-distance helioseismology analysis of dopplergrams provides maps of torsional oscillations and meridional flows. Meridional flow maps show a time-varying component that has a banded structure which matches the torsional oscillations with an equatorward migration over the solar cycle. The time-varying component of meridional flow consists of a flow diverging from the dominant latitude of magnetic activity. These maps are compared with other torsional oscillation maps and with magnetic flux maps, showing a strong correlation with active latitudes. These results demonstrate a strong link between the time-varying component of the meridional flow and the torsional oscillations.

  8. Solar 22 years cycle

    NASA Astrophysics Data System (ADS)

    Kotov, Valery A.; Sanchez, Francis M.

    2017-01-01

    Seven observatories performed in 1968-2015 numerous daily measurements of general magnetic field of the Sun seen as a star (of a mean line-of-sight field component of the visible solar hemisphere). The new data 2013-2015 confirmed the recent prediction about saw-edged profile of the mean curve of the Hale's 22 years magnetic cycle and, thus, a hypothesis about its cosmological (partial) origin. This is supported by a special analysis of epochs of extrema of Wolf's sunspot number, demonstrating a remarkable stability, since Galileo's time, of the initial phase of the cycle, which can hardly be explained by dynamo theory exclusively.

  9. Forecast of solar cycle 25

    NASA Astrophysics Data System (ADS)

    Krasotkin, Serge; Shmorgilov, Feodor

    The revised method of equal phase averaging was used to predict the main features of the solar cycle 25. The forecast of Wolf number values was obtained not only for solar cycle maximum but for 16 phases of the cycle. The double-peak structure of the cycle maximum phase is well seen. The problems of the long- and superlong-term forecasts of solar activity are discussed.

  10. Amplifying the Pacific Climate System Response to a Small 11-Year Solar Cycle Forcing

    DTIC Science & Technology

    2009-08-28

    climatological off-equatorial tropical precipitation maxima in the Pacific, lower the eastern equatorial Pacific sea surface temperatures during peaks...with an associated increase in trade wind strength that produces greater equa- torial ocean upwelling and lower equatorial SSTs in the eastern ...Pacific, a signal that was first discovered in observational data (1, 2). The en- hanced subsidence produces fewer clouds in the equatorial eastern Pacific

  11. Solar cycle effect in SBUV/SBUV 2 ozone data

    NASA Astrophysics Data System (ADS)

    Gruzdev, Aleksandr

    Effect of the 11-year solar cycle on stratospheric ozone is analyzed using the data of ozone measurements with SBUV/SBUV 2 instruments aboard Nimbus 7, NOAA 9, NOAA 11, NOAA 14, NOAA 16, and NOAA 17-NOAA 19 satellites for 1978-2012 (ftp://toms.gsfc.nasa.gov/pub/sbuv/). High-resolution spectral and cross-spectral methods as well as the method of multiple linear regression were used for the analysis. The regression model takes into account the annual variation, the linear trend, the solar cycle effect and the effects on ozone of the products of the Pinatubo volcano eruption and the quasi-biennial oscillations in the equatorial stratospheric wind. The cross-spectral analysis of ozone concentration and 10.7 cm solar radio flux shows that, generally, 11-year ozone variations in the upper stratosphere and lower mesosphere lag behind while ozone variations in the low-latitude lower stratosphere lead the solar cycle. The phase shift between the ozone variations and the solar cycle reaches pi/2 in 35-40 km layer over the tropics and in the southern hemisphere lower stratosphere. Calculations show that taking into account the phase shift is especially important for correct estimation of the ozone response to the solar cycle in the tropical middle stratosphere. Local maxima of ozone sensitivity to the 11-year solar cycle are noted around a year below the stratopause (45-50 km), in 30-35 km layer in the middle stratosphere, and in the polar lower stratosphere. The sensitivity of the ozone response to the solar cycle for the whole period of 1978-2012 is less than that for the period of 1978-2003 which does not include the 24th solar cycle with anomalously small amplitude. The ozone response is seasonally dependent. Maximal amplitudes of the ozone response are characteristic for polar latitudes during winter-spring periods. For example ozone changes related to the solar cycle can reach 5% in the low and middle latitudes during the 1978-2012 period, while winter-spring ozone

  12. Solar Cycle Predictions (Invited Review)

    NASA Astrophysics Data System (ADS)

    Pesnell, W. Dean

    2012-11-01

    Solar cycle predictions are needed to plan long-term space missions, just as weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on low-Earth orbit spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as the reduced propellant load is consumed more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5 - 20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations of how those predictions could be made more accurate in the future are discussed.

  13. Solar Cycle #24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean; Schatten, Kenneth

    2007-01-01

    We focus on two solar aspects related to flight dynamics. These are the solar dynamo and long-term solar activity predictions. The nature of the solar dynamo is central to solar activity predictions, and these predictions are important for orbital planning of satellites in low earth orbit (LEO). The reason is that the solar ultraviolet (UV) and extreme ultraviolet (EUV) spectral irradiances inflate the upper atmospheric layers of the Earth, forming the thermosphere and exosphere through which these satellites orbit. Concerning the dynamo, we discuss some recent novel approaches towards its understanding. For solar predictions we concentrate on a solar precursor method, in which the Sun s polar field plays a major role in forecasting the next cycle s activity based upon the Babcock- Leighton dynamo. With a current low value for the Sun s polar field, this method predicts that solar cycle #24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 130+ 30 (2 4, in the 2013 timeframe. One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. Concomitant effects of low solar activity upon satellites in LEO will need to be considered, such as enhancements in orbital debris. Support for our prediction of a low solar cycle #24 is borne out by the lack of new cycle sunspots at least through the first half of 2007. Usually at the present epoch in the solar cycle (-7+ years after the last solar maximum), for a normal size following cycle, new cycle sunspots would be seen. The lack of their appearance at this time is only consistent with a low cycle #24. Polar field observations of a weak magnitude are consistent with unusual structures seen in the Sun s corona. Polar coronal holes are the hallmarks of the Sun s open field structures. At present, it appears that the polar coronal holes are relatively weak, and there have been many equatorial coronal holes. This appears

  14. Solar Cycle #24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth; Pesnell, W. Dean

    2007-01-01

    We focus on two solar aspects related to flight dynamics. These are the solar dynamo and long-term solar activity predictions. The nature of the solar dynamo is central to solar activity predictions, and these predictions are important for orbital planning of satellites in low earth orbit (LEO). The reason is that the solar ultraviolet (UV) and extreme ultraviolet (EUV) spectral irradiances inflate the upper atmospheric layers of the Earth, forming the thermosphere and exosphere through which these satellites orbit. Concerning the dynamo, we discuss some recent novel approaches towards its understanding. For solar predictions we concentrate on a solar precursor method, in which the Sun's polar field plays a major role in forecasting the next cycle s activity based upon the Babcock-Leighton dynamo. With a current low value for the Sun s polar field, this method predicts that solar cycle #24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 130 plus or minus 30 (2 sigma), in the 2013 timeframe. One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. Concomitant effects of low solar activity upon satellites in LEO will need to be considered, such as enhancements in orbital debris. Support for our prediction of a low solar cycle #24 is borne out by the lack of new cycle sunspots at least through the first half of 2007. Usually at the present epoch in the solar cycle (approx. 7+ years after the last solar maximum), for a normal size following cycle, new cycle sunspots would be seen. The lack of their appearance at this time is only consistent with a low cycle #24. Polar field observations of a weak magnitude are consistent with unusual structures seen in the Sun s corona. Polar coronal holes are the hallmarks of the Sun's open field structures. At present, it appears that the polar coronal holes are relatively weak, and there have been many equatorial coronal holes

  15. Solar Cycle 24 and the Solar Dynamo

    NASA Astrophysics Data System (ADS)

    Pesnell, W. D.; Schatten, K.

    2007-05-01

    We will discuss the polar field precursor method for solar activity prediction, which predicts cycle 24 will be significantly lower than recent activity cycles, and some new ideas rejuvenating Babcock's shallow surface dynamo. The polar field precursor method is based on Babcock and Leighton's dynamo models wherein the polar field at solar minimum plays a major role in generating the next cycle's toroidal field and sunspots. Thus, by examining the polar fields of the Sun near solar minimum, a forecast for the next cycle's activity is obtained. With the current low value for the Sun's polar fields, this method predicts solar cycle 24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 135 ± 35 (2 σ), in the 2012-2013 timeframe (equivalent to smoothed Rz near 80 ± 35 [2 σ]). One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. We discuss unusual behavior in the Sun's polar fields that support this prediction. Normally, the solar precursor method is consistent with the geomagnetic precursor method, wherein geomagnetic variations are thought to be a good measure of the Sun's polar field strength. Because of the unusual polar field, the Earth does not appear to be currently bathed in the Sun's extended polar field (the interplanetary field), hence negating the primal cause behind the geomagnetic precursor technique. We also discuss how percolation may support Babcock's original shallow solar dynamo. In this process ephemeral regions from the solar magnetic carpet, guided by shallow surface fields, may collect to form pores and sunspots.

  16. Solar Cycle 24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Pesnell, W. D.; Schatten, K.

    2007-01-01

    We will discuss the polar field precursor method for solar activity prediction, which predicts cycle 24 will be significantly lower than recent activity cycles, and some new ideas rejuvenating Babcock's shallow surface dynamo. The polar field precursor method is based on Babcock and Leighton's dynamo models wherein the polar field at solar minimum plays a major role in generating the next cycle's toroidal field and sunspots. Thus, by examining the polar fields of the Sun near solar minimum, a forecast for the next cycle's activity is obtained. With the current low value for the Sun's polar fields, this method predicts solar cycle 24 will be one of the lowest in recent times, with smoothed F10.7 radio flux values peaking near 135 plus or minus 35 (2 sigma), in the 2012-2013 timeframe (equivalent to smoothed Rz near 80 plus or minus 35 [2 sigma]). One may have to consider solar activity as far back as the early 20th century to find a cycle of comparable magnitude. We discuss unusual behavior in the Sun's polar fields that support this prediction. Normally, the solar precursor method is consistent with the geomagnetic precursor method, wherein geomagnetic variations are thought to be a good measure of the Sun's polar field strength. Because of the unusual polar field, the Earth does not appear to be currently bathed in the Sun's extended polar field (the interplanetary field), hence negating the primal cause behind the geomagnetic precursor technique. We also discuss how percolation may support Babcock's original shallow solar dynamo. In this process ephemeral regions from the solar magnetic carpet, guided by shallow surface fields, may collect to form pores and sunspots.

  17. Solar Proton Events in Six Solar Cycles

    NASA Astrophysics Data System (ADS)

    Vitaly, Ishkov

    Based on materials the catalogs of solar proton events (SPE) in 1955 ‒ 2010 and list SPE for the current 24 solar cycle (SC) are examined confirmed SPE with E> 10 MeV proton flux in excess of 1 proton cm-2 s ster-1 (pfu) from Švestka and Simon’s (1955 - 1969) and 5 volumes Logachev’s (1970 - 2006) Catalogs of SPE. Historically thus it was formed, that the measurements of the proton fluxes began in the epoch “increased” solar activity (SC 18 ‒ 22), and includes transition period of the solar magnetic fields reconstruction from epoch “increased” to the epoch “lowered” solar activity (22 ‒ 23 SC). In current 24 SC ‒ first SC of the incipient epoch of “lowered” SA ‒ SPE realize under the new conditions, to that of previously not observed. As showed a study of five solar cycles with the reliable measurements of E> 10 MeV proton flux in excess of 1 pfu (1964 - 2013): ‒ a quantity of SPEs remained approximately identical in SC 20, 21, somewhat decreased in the initial solar cycle of the solar magnetic fields reconstruction period (22), but it returned to the same quantity in, the base for the period of reconstruction, SC 23. ‒ Into the first 5 years of the each solar cycle development the rate of the proton generation events noticeably increased in 22 cycles of solar activity and returned to the average in cycles 23 and 24. ‒ Extreme solar flare events are achieved, as a rule, in the solar magnetic fields reconstruction period (August - September 1859; June 1991; October ‒ November 2003.), it is confirmed also for SPE: the extreme fluxes of solar protons (S4) except one (August 1972) were occurred in period of perestroika (SC 22 and 23). This can speak, that inside the epochs SA, when the generation of magnetic field in the convective zone works in the steady-state regime, extreme SPE are improbable. ‒ The largest in the fluxes of protons (S3, S4) occur in the complexes of the active regions flare events, where magnetic field more

  18. Solar corona and prediction of the solar cycle 24 amplitude..

    NASA Astrophysics Data System (ADS)

    Pishkalo, M.

    2012-12-01

    Investigation of the solar cycle amplitude dependence on such quantitative parameters of shape and structure of the solar corona as indexes of photometrical and geometrical flattening and extension of polar coronal rays along the solar limb have been made. Observation of the solar corona during total solar eclipses in solar cycles 11-23 were used. The amplitude of solar cycle 24 was predicted on the basis of the parameters values at the cycle minimum. Solar cycle 24 is expected to be weaker than previous cycle 23. The Wolf number in the cycle maximum will amount to 83-113.

  19. Beginning of the new solar cycle (cycle 24) in the large-scale open solar magnetic field

    NASA Astrophysics Data System (ADS)

    Ivanov, K. G.; Kharshiladze, A. F.

    2008-06-01

    It is proposed to determined minimums of the 11-year solar cycles based on a minimal flux of the large-scale open solar magnetic field. The minimal fluxes before the finished cycle 23 (Carrington rotation CR 1904) and the started cycle 24 (CR 2054, April 2007) were equal to 1.8 × 1022 and 1.2 × 1022 μs, respectively. The long-term tendency toward an approach to a deep minimum of solar activity is confirmed. On the assumption that magnetic flux variations from minimums to maximums are proportional to each other, the anticipated value of the maximal Wolf number during cycle 24 is estimated as W max = 80.

  20. Solar Cycle Modulation of Total Irradiance: an Empirical Model from 1874 to 1988

    NASA Technical Reports Server (NTRS)

    Lean, J.; Foukal, P.

    1990-01-01

    Evidence acquired during the past decade indicates that over time scales of the solar cycle, enhanced emission from bright solar faculae cause significant variations in the sun's total irradiance even though, on shorter time scales, the most pronounced variations are those resulting from the passage of dark sunspots across the solar disc. An empirical model which accounts for the competing effects of dark sunspots and bright faculae has been developed from the available radiometry in cycle 21, and extended back to the beginning of solar cycle 12. According to this model, the largest 11-year modulation of total irradiance during the C20th occurred in the most recent cycle 21.

  1. The solar cycle variation of coronal mass ejections and the solar wind mass flux

    NASA Technical Reports Server (NTRS)

    Webb, David F.; Howard, Russell A.

    1994-01-01

    Coronal mass ejections (CMEs) are an important aspect of coronal physics and a potentially significant contributor to perturbations of the solar wind, such as its mass flux. Sufficient data on CMEs are now available to permit study of their longer-term occurrency patterns. Here we present the results of a study of CME occurrence rates over more than a complete 11-year solar sunspot cycle and a comparison of these rates with those of other activity related to CMEs and with the solar wind particle flux at 1 AU. The study includes an evaluation of correlations to the CME rates, which include instrument duty cycles, visibility functions, mass detection thresholds, and geometrical considerations. The main results are as follows: (1) The frequency of occurrence of CMEs tends to track the solar activity cycle in both amplitude and phase; (2) the CME rates from different instruments, when corrected for both duty cycles and visibility functions, are reasonably consistent; (3) considering only longer-term averages, no one class of solar activity is better correlated with CME rate than any other; (4) the ratio of the annualized CME to solar wind mass flux tends to track the solar cycle; and (5) near solar maximum, CMEs can provide a significant fraction (i.e., approximately equals 15%) of the average mass flux to the near-ecliptic solar wind.

  2. Preliminary prediction of the 25-thTH solar cycle parameters

    NASA Astrophysics Data System (ADS)

    Pishkalo, M.

    2014-12-01

    Solar activity varies with a period of about 11 years. The solar activity variations cause changes in the interplanetary and near-Earth space. The whole space weather is mainly controlled by the solar activity. Changes in space weather affect the operation of space-borne and ground-based technological systems such as manned space flights, aero-navigation and space navigation, radars, high-frequency radio communication, GPS navigation, ground power lines. The solar activity variations influence living organisms and the climate on Earth. That is why it is important to know the level of solar activity in a solar cycle in advance. Current solar activity is near the maximum of solar cycle 24. Maximal monthly sunspot number was 102.8 in February 2014 and smoothed one was 75.4 in November 2013 (preliminary). Taking it into account and using correlation relations and regression equations from (Pishkalo, 2014: Solar Phys., vol. 289, 1815) we can estimate duration of solar cycle 24 and then predict parameters of solar cycle 25. Precursors in our calculations are the estimated duration of solar cycle 24 and sunspot number at the end of the cycle. We found that minimum and maximum of solar cycle 25 in monthly sunspot numbers will amount to 5 in April–June of 2020 and 105–110 in October–December of 2024, respectively. Solar cycle 25 will be stronger than the current cycle 24. No very deep drop in solar activity similar to Dalton or Maunder minimums was predicted.

  3. Predictions of the onset of mini ice age in the 25th solar cycle

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv

    2016-07-01

    Predictions of the ir-regularty in the 11 year heartbeat of the sun due to asyncronous of the two layered dynamo effect would result in mini ice age as in the Maunder minimum.The onset of this event is expected in the begining of 25th solar cycle and would go to its maximum in the 26th solar cycle.The minimum temperature is expected in 2028 due to the fall of solar activity by 60 % termed as solar hibernation.The predictions are based on the observations obtained by the Royal Greenwich observatory since 1874. Keywords: Dynamo effect,munder minimum,Solar hybernation

  4. A Statistical Test of Uniformity in Solar Cycle Indices

    NASA Technical Reports Server (NTRS)

    Hathaway David H.

    2012-01-01

    Several indices are used to characterize the solar activity cycle. Key among these are: the International Sunspot Number, the Group Sunspot Number, Sunspot Area, and 10.7 cm Radio Flux. A valuable aspect of these indices is the length of the record -- many decades and many (different) 11-year cycles. However, this valuable length-of-record attribute has an inherent problem in that it requires many different observers and observing systems. This can lead to non-uniformity in the datasets and subsequent erroneous conclusions about solar cycle behavior. The sunspot numbers are obtained by counting sunspot groups and individual sunspots on a daily basis. This suggests that the day-to-day and month-to-month variations in these numbers should follow Poisson Statistics and be proportional to the square-root of the sunspot numbers themselves. Examining the historical records of these indices indicates that this is indeed the case - even with Sunspot Area and 10.7 cm Radio Flux. The ratios of the RMS variations to the square-root of the indices themselves are relatively constant with little variation over the phase of each solar cycle or from small to large solar cycles. There are, however, important step-like changes in these ratios associated with changes in observer and/or observer system. Here we show how these variations can be used to construct more uniform datasets.

  5. A Synthesis of Solar Cycle Prediction Techniques

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Wilson, Robert M.; Reichmann, Edwin J.

    1999-01-01

    A number of techniques currently in use for predicting solar activity on a solar cycle timescale are tested with historical data. Some techniques, e.g., regression and curve fitting, work well as solar activity approaches maximum and provide a month-by-month description of future activity, while others, e.g., geomagnetic precursors, work well near solar minimum but only provide an estimate of the amplitude of the cycle. A synthesis of different techniques is shown to provide a more accurate and useful forecast of solar cycle activity levels. A combination of two uncorrelated geomagnetic precursor techniques provides a more accurate prediction for the amplitude of a solar activity cycle at a time well before activity minimum. This combined precursor method gives a smoothed sunspot number maximum of 154 plus or minus 21 at the 95% level of confidence for the next cycle maximum. A mathematical function dependent on the time of cycle initiation and the cycle amplitude is used to describe the level of solar activity month by month for the next cycle. As the time of cycle maximum approaches a better estimate of the cycle activity is obtained by including the fit between previous activity levels and this function. This Combined Solar Cycle Activity Forecast gives, as of January 1999, a smoothed sunspot maximum of 146 plus or minus 20 at the 95% level of confidence for the next cycle maximum.

  6. Drought over Seoul and Its Association with Solar Cycles

    NASA Astrophysics Data System (ADS)

    Park, Jong-Hyeok; Chang, Heon-Young

    2013-12-01

    We have investigated drought periodicities occurred in Seoul to find out any indication of relationship between drought in Korea and solar activities. It is motivated, in view of solar-terrestrial connection, to search for an example of extreme weather condition controlled by solar activity. The periodicity of drought in Seoul has been re-examined using the wavelet transform technique as the consensus is not achieved yet. The reason we have chosen Seoul is because daily precipitation was recorded for longer than 200 years, which meets our requirement that analyses of drought frequency demand long-term historical data to ensure reliable estimates. We have examined three types of time series of the Effective Drought Index (EDI). We have directly analyzed EDI time series in the first place. And we have constructed and analyzed time series of histogram in which the number of days whose EDI is less than -1.5 for a given month of the year is given as a function of time, and one in which the number of occasions where EDI values of three consecutive days are all less than -1.5 is given as a function of time. All the time series data sets we analyzed are periodic. Apart from the annual cycle due to seasonal variations, periodicities shorter than the 11 year sunspot cycle, ~ 3, ~ 4, ~ 6 years, have been confirmed. Periodicities to which theses short periodicities (shorter than Hale period) may be corresponding are not yet known. Longer periodicities possibly related to Gleissberg cycles, ~ 55, ~ 120 years, can be also seen. However, periodicity comparable to the 11 year solar cycle seems absent in both EDI and the constructed data sets.

  7. Skin Cancer, Irradiation, and Sunspots: The Solar Cycle Effect

    PubMed Central

    Zurbenko, Igor

    2014-01-01

    Skin cancer is diagnosed in more than 2 million individuals annually in the United States. It is strongly associated with ultraviolet exposure, with melanoma risk doubling after five or more sunburns. Solar activity, characterized by features such as irradiance and sunspots, undergoes an 11-year solar cycle. This fingerprint frequency accounts for relatively small variation on Earth when compared to other uncorrelated time scales such as daily and seasonal cycles. Kolmogorov-Zurbenko filters, applied to the solar cycle and skin cancer data, separate the components of different time scales to detect weaker long term signals and investigate the relationships between long term trends. Analyses of crosscorrelations reveal epidemiologically consistent latencies between variables which can then be used for regression analysis to calculate a coefficient of influence. This method reveals that strong numerical associations, with correlations >0.5, exist between these small but distinct long term trends in the solar cycle and skin cancer. This improves modeling skin cancer trends on long time scales despite the stronger variation in other time scales and the destructive presence of noise. PMID:25126567

  8. Central antarctic climate response to the solar cycle

    NASA Astrophysics Data System (ADS)

    Volobuev, D. M.

    2014-05-01

    Antarctic "Vostok" station works most closely to the center of the ice cap among permanent year-around stations. Climate conditions are exclusively stable: low precipitation level, cloudiness and wind velocity. These conditions can be considered as an ideal model laboratory to study the surface temperature response on solar irradiance variability during 11-year cycle of solar activity. Here we solve an inverse heat conductivity problem: calculate the boundary heat flux density (HFD) from known evolution of temperature. Using meteorological temperature record during (1958-2011) we calculated the HFD variation about 0.2-0.3 W/m2 in phase with solar activity cycle. This HFD variation is derived from 0.5 to 1 °C temperature variation and shows relatively high climate sensitivity per 0.1 % of solar radiation change. This effect can be due to the polar amplification phenomenon, which predicts a similar response 0.3-0.8 °C/0.1 % (Gal-Chen and Schneider in Tellus 28:108-121, 1975). The solar forcing (TSI) is disturbed by volcanic forcing (VF), so that their linear combination TSI + 0.5VF empirically provides higher correlation with HFD (r = 0.63 ± 0.22) than TSI (r = 0.50 ± 0.24) and VF (r = 0.41 ± 0.25) separately. TSI shows higher wavelet coherence and phase agreement with HFD than VF.

  9. Solar Cycle Variability in Tropical Column Ozone

    NASA Astrophysics Data System (ADS)

    Yung, Y. L.; Liang, M.; Li, K.; Jiang, X.; Camp, C. D.

    2011-12-01

    Using an empirical orthogonal function (EOF) method [Camp et al., 2003], we analyzed the Merged Ozone Data (MOD) set from late 1978 to the present. The decadal variability of column ozone in the tropics follows that of the sun over three solar cycles. The peak-to-peak amplitude is about 10 DU (Dobson Units), consistent with the conclusion of Camp et al. [2003], who analyzed the MOD data up to and including 2000. Previous attempts to model the amplitude of the observed solar cycle in ozone were unsuccessful, as models tended to underestimate the solar cycle effect. Using the Whole Atmosphere Community Climate Model (WACCM) in combination with the latest satellite measurements of solar variability in the UV [McClintock et al., 2005; Harder et al., 2009], we correctly simulate the solar cycle signal in the total column ozone for the first time. The implications for solar forcing on middle atmosphere chemistry are discussed.

  10. Solar activity cycle - History and predictions

    SciTech Connect

    Withbroe, G.L. )

    1989-12-01

    The solar output of short-wavelength radiation, solar wind, and energetic particles depends strongly on the solar cycle. These energy outputs from the sun control conditions in the interplanetary medium and in the terrestrial magnetosphere and upper atmosphere. Consequently, there is substantial interest in the behavior of the solar cycle and its effects. This review briefly discusses historical data on the solar cycle and methods for predicting its further behavior, particularly for the current cycle, which shows signs that it will have moderate to exceptionally high levels of activity. During the next few years, the solar flux of short-wavelength radiation and particles will be more intense than normal, and spacecraft in low earth orbit will reenter earlier than usual. 46 refs.

  11. Solar Cycle Variations and Equatorial Oscillations: Modeling Study

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Chan, K. L.; Porter, H. S.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    Solar cycle activity effects (SCAE) in the lower and middle atmosphere, reported in several studies, are difficult to explain on the basis of the small changes in solar radiation that accompany the 11-year cycle, It is therefore natural to speculate that dynamical processes may come into play to produce a leverage. Such a leverage may be provided by the Quasi-Biennial Oscillation (QBO) in the zonal circulation of the stratosphere, which has been linked to solar activity variations. Driven primarily by wave mean flow interaction, the QBO period and its amplitude are variable but are also strongly influenced by the seasonal cycle in the solar radiation. This influence extends to low altitudes referred to as "downward control". Relatively small changes in solar radiative forcing can produce small changes in the period and phase of the QBO, but this in turn can produce measurable differences in the wind field. Thus, the QBO may be an amplifier of solar activity variations and a natural conduit of these variations to lower altitudes. To test this hypothesis, we conducted experiments with a 2D (two-dimensional) version of our Numerical Spectral Model that incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). Solar cycle radiance variations (SCRV) are accounted for by changing the radiative heating rate on a logarithmic scale from 0.1 % at the surface to 1 % at 50 km to 10% at 100 km. With and without SCRV, but with the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the SCAE in the zonal circulation. The numerical results indicate that, under certain conditions, the SCAE is significant and can extend to lower altitudes where the SCRV is inconsequential. At 20-km the differences in the modeled wind velocities are as large as 5 m/s. For a modeled QBO period of 30 months, we find that the seasonal cycle in the solar forcing (through the Semi-annual Oscillation (SAO)) acts as a strong pacemaker to lockup the

  12. Solar cycle 24 from the standpoint of solar paleoastrophysics

    NASA Astrophysics Data System (ADS)

    Ogurtsov, M. G.

    2016-03-01

    The predictions of the maximum yearly mean sunspot number in the current cycle 24 made by means of the astrophysical approach (by analyzing the instrumental data on solar activity and using various dynamo models) and the paleoastrophysical approach (by analyzing the paleoreconstructions of solar activity spanning the interval from 8555 BC to 1605 AD) are compared. The paleoastrophysical predictions are shown to be considerably more accurate. The amplitude of the next cycle 25 is predicted. It is shown that from the standpoint of solar paleoastrophysics, cycle 25 will most likely be of medium power, R max(25) = 85.0 ± 30.5.

  13. An early prediction of the maximum amplitude of the solar cycle 25

    NASA Astrophysics Data System (ADS)

    Helal, Hamid R.; Galal, A. A.

    2013-05-01

    A solar activity precursor technique of spotless event has been currently used to predict the strengths and the times of rise of the 11-year coming cycles. This simple statistical method has been previously applied to predict the maximum amplitudes and the times of rises of cycles 22 and 23. The results obtained are successful for both cycles. A developed version of the suggested method was previously used to make an early forecast of the characteristic parameters of the cycle 24. In this work the preliminarily predicted parameters of the cycle 24 are checked using observed values of the spotless events. In addition, the developed method is also applied to forecast the maximum amplitude and time of rise of the 25th solar cycle. The maximum Wolf number and time of rise of the latter cycle are found to be 118.2 and 4.0 years respectively.

  14. A Decline in Solar Cycle Strength

    NASA Astrophysics Data System (ADS)

    Chapman, G. A.; de Toma, G.; Cookson, A.

    2013-12-01

    The strength of solar activity appears to be in decline over the past three solar cycles. The decline is seen in sunspot area, facular/network area and the sunspot number. In addition, cycle 24 has been unusual in that many, if not most, of the bipolar sunspot groups have had only a leader spot with no follower spot. This research was partially supported by grants from NSF and NASA. Corrected spot area from CFDT1 at the San Fernando Observatory

  15. Solar proton events during solar cycles 19, 20, and 21

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Armstrong, T. P.; Dao-Gibner, L.; Silverman, S.

    1990-01-01

    Earlier studies based on a single solar cycle had resulted in a sharp division of events into 'ordinary' and 'anomalously large' events. Two such entirely separate distributions imply two entirely separate acceleration mechanisms, one common and the other very rare. The sharp division is neither required nor justified by this larger sample. Instead the event intensity forms a smooth distribution for intensities up to the largest observed implying that any second acceleration mechanism cannot be rare. Also, a clear bimodal variation of annual integrated flux with solar cycle phase but no statistically significant tendency for the large events to avoid sunspot maximum is found. There is almost no relation between the maximum sunspot number in a solar cycle and the solar cycle integrated flux. It is also found that for annual sunspot numbers greater than 35 there is no relation whatsoever between the annual sunspot numbers and annual integrated flux.

  16. Changes of solar extreme ultraviolet spectrum in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Huang, Jianping; Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo

    2016-07-01

    Following the extreme solar minimum during 2008-2009, solar activity keeps low in solar cycle 24 (SC24) and is making SC24 the weakest one of recent cycles. In this paper, using observations from Earth-orbiting satellites, we compare the solar extreme ultraviolet (EUV) irradiance between SC23 and SC24 and investigate the solar cycle change of linear dependence of EUV on the P ((F10.7 + F10.7A)/2) and Mg II core-to-wing ratio indices. The Bremen composite Mg II index is strongly correlated with P over the two solar cycles, while this is not the case for the Laboratory for Atmospheric and Space Physics (LASP) composite Mg II index, so we focus on the different dependence of EUV on the P and LASP Mg II indices. As a result we find that three coronal emissions (Fe XV at 28.4 nm and 41.7 nm and Fe XVI at 33.5 nm) brighten in SC24 relative to P; i.e., the magnitude of irradiance is higher than in SC23 at the same level of P. But relative to the LASP Mg II index, these emissions show no appreciable solar cycle differences. By contrast, the H I Lyman α at 121.6 nm dims in SC24 relative to the LASP Mg II but shows identical dependence on P in the two solar cycles. This result seems to contradict a well-accepted fact that chromospheric and transition region emissions are better represented by the Mg II index and coronal lines by F10.7. For the different solar cycle variability of EUV in SC24, whether it is caused by source changes on the Sun is still unclear, but we suggest that it needs to be considered in proxy modeling of the EUV irradiance and aeronomic studies.

  17. An 'extended Solar CYCLE` as Observed in fe XIV

    NASA Astrophysics Data System (ADS)

    Altrock, Richard C.

    1997-02-01

    Investigation of the behavior of coronal intensity above the limb in Fe XIV emission (530.3 nm) obtained at the National Solar Observatory at Sacramento Peak over the last 23 years has resulted in the confirmation of a second set of zones of solar activity at high latitudes, separate from the Main Activity Zones (MAZ). Localized high-latitude intensity maxima, which I will call High-latitude Emission Features (HEF), are observed at 0.15 solar radii above the limb throughout the solar cycle. They persist long enough at a given latitude to be visible in long-term (e.g., annual) averages. I identify two types of HEF. Poleward-moving HEF, which may be identified with the "Rush to the Poles" phenomenon seen in polar-crown prominences, were first seen to appear in this investigation near latitude 60 degrees in 1978. In 1979 equatorward-moving HEF branched off from the poleward-moving HEF (which continued on to reach the pole in 1980) at a latitude of 70 to 80 degrees. They evolved approximately parallel to the MAZ. Near solar minimum, these HEF evolved into the MAZ of Cycle 22, and the emission continues its path towards the equator, where it should disappear soon. Currently, it is clear that the pattern seen earlier is repeating. The poleward-moving HEF became apparent near the beginning of 1988 near 50 to 60 degrees latitude. The northern poleward-moving HEF reached the pole and disappeared in 1990. The southern poleward-moving HEF moved more slowly, reaching the pole and disappearing in 1991. The equatorward-moving HEF that are the precursors of Cycle 23 appeared in 1989 to 1990 and began to move approximately parallel to the MAZ of Cycle 22. Based on inferences from previous Cycles, we can expect these HEF to continue to the equator, with emission ceasing there near 2009. These recent observations increase the evidence for an "Extended" Solar Cycle that begins every 11 years but lasts for approximately 19-20 years.

  18. Global water cycle and solar activity variations

    NASA Astrophysics Data System (ADS)

    Al-Tameemi, Muthanna A.; Chukin, Vladimir V.

    2016-05-01

    The water cycle is the most active and most important component in the circulation of global mass and energy in the Earth system. Furthermore, water cycle parameters such as evaporation, precipitation, and precipitable water vapour play a major role in global climate change. In this work, we attempt to determine the impact of solar activity on the global water cycle by analyzing the global monthly values of precipitable water vapour, precipitation, and the Solar Modulation Potential in 1983-2008. The first object of this study was to calculate global evaporation for the period 1983-2008. For this purpose, we determined the water cycle rate from satellite data, and precipitation/evaporation relationship from 10 years of Planet Simulator model data. The second object of our study was to investigate the relationship between the Solar Modulation Potential (solar activity index) and the evaporation for the period 1983-2008. The results showed that there is a relationship between the solar modulation potential and the evaporation values for the period of study. Therefore, we can assume that the solar activity has an impact on the global water cycle.

  19. Missing solar cycle hypothesis and basic statistical regularities of solar cycles

    NASA Astrophysics Data System (ADS)

    Ogurtsov, M. G.

    2012-12-01

    The basic statistical properties of solar cycles, including the Gnevyshev-Ol' rule, the Waldmeier effect, and the amplitude-period effect, are tested using data on the number of sunspot groups for 1700-1996, considering the hypothesis about a missing solar cycle in the late 18th century. The results show that the division of the long cycle of 1784-1800 into two short cycles—1784-1793 and 1793-1800—alters significantly the pattern of the solar cycles. The Gnevyshev-Ol' cycle intensity effect becomes stronger, and almost all other statistical effects grow weaker. This change is due to the fact that the short and weak cycle of 1793-1800 is statistically very unusual and its features are very different from those of other solar cycles.

  20. Magnetic network elements in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Jin, Chunlan; Wang, Jingxiu

    2013-07-01

    In this report, we present our recent effort to understand the cyclic behavior of network magnetic elements based on the unique database from full-disk observations provided by Michelson Doppler Imager on board the Solar and Heliospheric Observatory in the interval including the entire cycle 23. The following results are unclosed. (1) The quiet regions dominate the solar magnetic flux for about 8 years in solar cycle 23, and from the solar minimum to maximum they contribute (0.94-1.44)×1023Mx flux to the solar photosphere. In the entire cycle 23, the magnetic flux of the quiet regions is 1.12 times that of active regions. The occupation ratio of quiet region flux equally characterizes the course of a solar cycle. (2) With the increasing magnetic flux per element, the variations of numbers and total flux of the network elements show three-fold scenario: no-correlation, anti-correlation, and correlation with sunspots, respectively. The anti-correlated elements covering the range of (3-32)×1018Mx occupy 77% of total element number and 37% of quiet Sun flux. (3) The time-latitude distribution of anti-correlated magnetic elements is out of phase with that of sunspots, while the correlated elements display the similar butterfly diagram of sunspots but with wider latitude distribution. These results imply that the correlated elements are the debris of decayed sunspots, and the source of anti-correlated elements is modulated by sunspot magnetic field.

  1. Examination of Solar Cycle Statistical Model and New Prediction of Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Wilson, John W.

    2000-01-01

    Sunspot numbers in the current solar cycle 23 were estimated by using a statistical model with the accumulating cycle sunspot data based on the odd-even behavior of historical sunspot cycles from 1 to 22. Since cycle 23 has progressed and the accurate solar minimum occurrence has been defined, the statistical model is validated by comparing the previous prediction with the new measured sunspot number; the improved sunspot projection in short range of future time is made accordingly. The current cycle is expected to have a moderate level of activity. Errors of this model are shown to be self-correcting as cycle observations become available.

  2. Solar cycle signal in Earth rotation: nonstationary behavior.

    PubMed

    Currie, R G

    1981-01-23

    Following the discovery of the 11-year solar cycle signal in earth rotation, linear techniques were employed to investigate the amplitude and phase of the difference between ephemeris time and universal time (DeltaT) as a function of time. The amplitude is nonstationary. This difference was related to Delta(LOD), the difference between the length of day and its nominal value. The 11-year term in Delta(LOD) was 0.8 millisecond at the close of the 18th century and decreased below noise level from 1840 to 1860. From 1875 to 1925, Delta(LOD) was about 0.16 millisecond, and it decreased to about 0.08 millisecond by the 1950's. Except for anomalous behavior from 1797 to 1838, DeltaT lags sunspot numbers by 3.0 +/- 0.4 years. Since DeltaT lags Delta(LOD) by 2.7 years, the result is that Delta(LOD) is approximately in phase with sunspot numbers.

  3. Solar Observations In Cycle 4 Of ALMA

    NASA Astrophysics Data System (ADS)

    Shimojo, Masumi; ALMA Solar Development Team

    2016-07-01

    The Sun is one of scientific targets of the Atacama Large Millimeter/sub-millimeter Array (ALMA). However, solar observations had not been offered until Cycle 3, because of a lot of difficulties for observing the Sun with the radio interferometer for night astronomy. We have been developing observing schemes for the Sun since 2010, and the joint ALMA observatory started to offer solar observations from Cycle 4 at last. Since the special treatments are needed for solar observations, there are some limitations for observing the Sun in comparison with the observations of other celestial targets. We held the commissioning campaign in December 2015 for verifying the observing modes, and the images synthesized from the commissioning data show us new sights of solar physics. The data obtained with the ALMA will bring about great scientific achievements.

  4. CORRELATION BETWEEN THE 22-YEAR SOLAR MAGNETIC CYCLE AND THE 22-YEAR QUASICYCLE IN THE EARTH'S ATMOSPHERIC TEMPERATURE

    SciTech Connect

    Qu Weizheng; Zhao Jinping; Huang Fei; Deng Shenggui

    2012-07-15

    According to the variation pattern of the solar magnetic field polarity and its relation to the relative sunspot number, we established the time series of the sunspot magnetic field polarity index and analyzed the strength and polarity cycle characteristics of the solar magnetic field. The analysis showed the existence of a cycle with about a 22-year periodicity in the strength and polarity of the solar magnetic field, which proved the Hale proposition that the 11-year sunspot cycle is one-half of the 22-year solar magnetic cycle. By analyzing the atmospheric temperature field, we found that the troposphere and the stratosphere in the middle latitude of both the northern and southern hemispheres exhibited a common 22-year quasicycle in the atmospheric temperature, which is believed to be attributable to the 22-year solar magnetic cycle.

  5. Solar Cycles - to Updating Basic Parameters

    NASA Astrophysics Data System (ADS)

    Ryabov, M. I.

    Examining daily and monthly averages of solar activity index of the northern and southern hemispheres on the total area of spots-Sp (12-24 cycles, 1874-2014), the Wolf numbers-W (22-24 cycles, 1992-2014). Application of band pass filtering based on Wavelet analysis shows that 'Northern' and 'Southern' cycles have their own start time, rise phase, the phases of decline, maximum and minimum. The formation of each cycle on all indices of activity is determined as a result of the combined effect of the long-period and shortperiodic processes.

  6. Solar Spectral Irradiance Changes During Cycle 24

    NASA Technical Reports Server (NTRS)

    Marchenko, Sergey; Deland, Matthew

    2014-01-01

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by approximately 0.6% +/- 0.2% around 265 nm. These changes gradually diminish to 0.15% +/- 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar "continuum." Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar "continuum," the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at lambda approximately or greater than 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  7. On Solar Cycle Predictions and Reconstructions

    DTIC Science & Technology

    2008-12-01

    for grand solar minima and to reconstruct the relative sunspol number in the Maunder minimum . Methods. We calculate the asymmetry of the ascending...was identified in the asymmetry data. The maximal smoothed monthly sunspot number during the Maunder minimum was reconstructed and found to be in the...cycle, to investigate proxies for grand solar minima and to reconstruct the relative sunspot number in the Maunder minimum . Methods. We calculate the

  8. Prediction Methods in Solar Sunspots Cycles

    PubMed Central

    Ng, Kim Kwee

    2016-01-01

    An understanding of the Ohl’s Precursor Method, which is used to predict the upcoming sunspots activity, is presented by employing a simplified movable divided-blocks diagram. Using a new approach, the total number of sunspots in a solar cycle and the maximum averaged monthly sunspots number Rz(max) are both shown to be statistically related to the geomagnetic activity index in the prior solar cycle. The correlation factors are significant and they are respectively found to be 0.91 ± 0.13 and 0.85 ± 0.17. The projected result is consistent with the current observation of solar cycle 24 which appears to have attained at least Rz(max) at 78.7 ± 11.7 in March 2014. Moreover, in a statistical study of the time-delayed solar events, the average time between the peak in the monthly geomagnetic index and the peak in the monthly sunspots numbers in the succeeding ascending phase of the sunspot activity is found to be 57.6 ± 3.1 months. The statistically determined time-delayed interval confirms earlier observational results by others that the Sun’s electromagnetic dipole is moving toward the Sun’s Equator during a solar cycle. PMID:26868269

  9. Breathing of heliospheric structures triggered by the solar-cycle activity

    NASA Astrophysics Data System (ADS)

    Scherer, K.; Fahr, H. J.

    2003-06-01

    Solar wind ram pressure variations occuring within the solar activity cycle are communicated to the outer heliosphere as complicated time-variabilities, but repeating its typical form with the activity period of about 11 years. At outer heliospheric regions, the main surviving solar cycle feature is a periodic variation of the solar wind dynamical pressure or momentum flow, as clearly recognized by observations of the VOYAGER-1/2 space probes. This long-periodic variation of the solar wind dynamical pressure is modeled here through application of appropriately time-dependent inner boundary conditions within our multifluid code to describe the solar wind - interstellar medium interaction. As we can show, it takes several solar cycles until the heliospheric structures adapt to an average location about which they carry out a periodic breathing, however, lagged in phase with respect to the solar cycle. The dynamically active heliosphere behaves differently from a static heliosphere and especially shows a historic hysteresis in the sense that the shock structures move out to larger distances than explained by the average ram pressure. Obviously, additional energies are pumped into the heliosheath by means of density and pressure waves which are excited. These waves travel outwards through the interface from the termination shock towards the bow shock. Depending on longitude, the heliospheric sheath region memorizes 2-3 (upwind) and up to 6-7 (downwind) preceding solar activity cycles, i.e. the cycle-induced waves need corresponding travel times for the passage over the heliosheath. Within our multifluid code we also adequately describe the solar cycle variations in the energy distributions of anomalous and galactic cosmic rays, respectively. According to these results the distribution of these high energetic species cannot be correctly described on the basis of the actually prevailing solar wind conditions.

  10. The role of ozone feedback in modulating the atmospheric response to the solar cycle forcing

    NASA Astrophysics Data System (ADS)

    Bednarz, Ewa; Maycock, Amanda; Braesicke, Peter; Telford, Paul; Abraham, Luke; Pyle, John

    2016-04-01

    The irradiance changes between the 11-year solar cycle maximum and minimum lead to increased stratospheric temperatures via enhanced UV absorption by ozone. This direct radiative response is strengthened by increased photochemical ozone production. While in reality these two processes are closely coupled, not all global climate models include interactive chemistry and may not therefore represent the solar-ozone feedback in an internally consistent manner. This study investigates the role of the representation of ozone for the modeled solar cycle response. We use a version of the UM-UKCA chemistry-climate model. We perform a 64-year perpetual solar minimum integration with non-interactive treatment of ozone, i.e. where ozone is externally prescribed for the radiative calculations. This is complemented with two analogous non-interactive solar maximum integrations that include an increase in solar irradiance, but which differ in their representation of the solar ozone response. We show that the representation of the solar-ozone feedback has a first-order impact on the simulated yearly mean short wave heating rates and temperature responses to the 11-year solar cycle forcing. However, despite the substantial differences in the tropical temperature changes, the Northern Hemisphere high latitude circulation responses are broadly similar in both experiments, and show strengthening of the polar vortex during winter and a weakening in March. Therefore, the representation of the prescribed solar-ozone response appears unlikely to explain the substantial spread in the solar cycle dynamical responses in different models. Lastly, we compare these results with an analogous solar maximum/minimum pair in which ozone is calculated by the photochemical scheme in a self-consistent manner. We show that the use of interactive vs non-interactive treatment of ozone does not strongly affect the yearly mean tropical temperature response. However, the results suggest potential differences

  11. THE BIMODAL STRUCTURE OF THE SOLAR CYCLE

    SciTech Connect

    Du, Z. L.

    2015-05-01

    Some properties of the 11 yr solar cycle can be explained by the current solar dynamo models. However, some other features remain not well understood such as the asymmetry of the cycle, the double-peaked structure, and the “Waldmeier effect” that a stronger cycle tends to have less rise time and a shorter cycle length. We speculate that the solar cycle is governed by a bi-dynamo model forming two stochastic processes depicted by a bimodal Gaussian function with a time gap of about 2 yr, from which the above features can be reasonably explained. The first one describes the main properties of the cycle dominated by the current solar dynamo models, and the second one occurs either in the rising phase as a short weak explosive perturbation or in the declining phase as a long stochastic perturbation. The above function is the best one selected from several in terms of the Akaike information criterion. Through analyzing different distributions, one might speculate about the dominant physical process inside the convection zone. The secondary (main) process is found to be closely associated with complicated (simple) active ranges. In effect, the bi-dynamo model is a reduced form of a multi-dynamo model, which could occur from the base of the convection zone through its envelope and from low to high heliographic latitude, reflecting the active belts in the convection zone. These results are insensitive to the hemispheric asymmetry, smoothing filters, and distribution functions selected and are expected to be helpful in understanding the formation of solar and stellar cycles.

  12. Detection of the climate response to the solar cycle

    SciTech Connect

    Stevens, M.J.; North, G.R.

    1996-09-15

    Optimal space-time signal processing is used to infer the amplitude of the large-scale, near-surface temperature response to the {open_quotes}11 year{close_quotes} solar cycle. The estimation procedure involves the following steps. (1) By correlating 14 years of monthly total solar irradiance measurements made by the Nimbus-7 satellite and monthly Wolf sunspot numbers, a monthly solar irradiance forcing function is constructed for the years 1894-1993. (2) Using this forcing function, a space-time waveform of the climate response for the same 100 years is generated from an energy balance climate model. (3) The space-time covariance statistics in the frequency band (16.67 yr){sup {minus}1}-(7.14 yr){sup {minus}1} are calculated using control runs from two different coupled ocean-atmosphere global climate models. (4) Using the results from the last two steps, an optimal filter is constructed and applied to observed surface temperature data for the years 1894-1993. (5) An estimate of the ratio of the real climate response, contained in the observed data, and the model generated climate response from step 2 is given, as well as an estimate of its uncertainty. A number of consistency checks are presented, such as using data from different regions of the earth to calculate this ratio and using data lagged up to {+-}5 yr. The authors findings allow them to reject the null hypothesis, that no response to the solar cycle is present in the data, at a confidence level of 97.4%. 44 refs., 15 figs., 3 tabs.

  13. Solar Cycle Variation of CMEs and CIRs

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2011-01-01

    Coronal mass ejections (CMEs) and high-speed solar wind streams (HSS) are two solar phenomena that produce large-scale structures in the interplanetary (IP) medium. CMEs evolve into interplanetary CMEs (ICMEs) and the HSS result in corotating interaction regions (CIRs) when they interact with preceding slow solar wind. CMEs and CIRs originate from closed (active region and filament region) and open (corona) hole) magnetic field regions on the Sun, respectively. These two types of mass emissions from the Sun are responsible for the largest effects on the heliosphere, particularly on Earth's space environment. This paper discussed how these structures and their solar sources vary with the solar cycle and the consequent changes in the geospace impact.

  14. Changes of solar extreme ultraviolet spectrum in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo; Huang, Jianping

    2016-07-01

    Following the extreme solar minimum during 2008 - 2009, solar activity keeps low in solar cycle 24 (SC24) and is making SC24 the weakest one of recent cycles. In this paper, we compare the solar EUV spectral irradiance between SC23 and SC24, using the measurements by the Solar EUV Experiment (SEE) on the Thermospheric Ionospheric Mesospheric Energy and Dynamics (TIMED) spacecraft. The EUV spectrum varies with solar activity, and is in general a linear function of a proxy index P= (F10.7 + F10.7A)/2. However, we find the slope of this function, i.e., the change rate of irradiance at each wavelength with P, differs between SC23 and SC24. Consequently, at a given P level, the irradiance in SC24 is higher at wavelength of 30 - 50 nm, but lower at 60 - 120 nm and longward of 140 nm; the inter-cycle variation of EUV irradiance at some wavelengths can be 30 - 40% in absolute flux. We further examine 38 most intense emission lines and find that, taking P as a reference, most of the bright coronal lines get stronger in SC24 and, by contrast, those from the chromosphere and transition region have less variability in SC24. We therefore suggest that, the empirical relation between solar EUV and P, which is derived from observations in previous solar cycles, may not adapt to SC24. The changes in EUV spectrum need to be considered in the models for aeronomic study, especially those using F10.7 index as an input parameter.

  15. Coronal Activity and Extended Solar Cycles

    NASA Astrophysics Data System (ADS)

    Altrock, R. C.

    2012-12-01

    Wilson et al. (1988, Nature 333, 748) discussed a number of solar parameters, which appear at high latitudes and gradually migrate towards the equator, merging with the sunspot "butterfly diagram". They found that this concept had been identified by earlier investigators extending back to 1957. They named this process the "Extended Solar Cycle" (ESC). Altrock (1997, Solar Phys. 170, 411) found that this process continued in Fe XIV 530.3 nm emission features. In cycles 21 - 23 solar maximum occurred when the number of Fe XIV emission regions per day > 0.19 (averaged over 365 days and both hemispheres) first reached latitudes 18°, 21° and 21°, for an average of 20° ± 1.7°. Other recent studies have shown that Torsional Oscillation (TO) negative-shear zones are co-located with the ESC from at least 50° down to the equator and also in the zones where the Rush to the Poles occur. These phenomena indicate that coronal activity occurring up to 50° and higher latitudes is related to TO shear zones, another indicator that the ESC is an important solar process. Another high-latitude process, which appears to be connected with the ESC, is the "Rush to the Poles" ("Rush") of polar crown prominences and their associated coronal emission, including Fe XIV. The Rush is is a harbinger of solar maximum (cf. Altrock, 2003, Solar Phys. 216, 343). Solar maximum in cycles 21 - 23 occurred when the center line of the Rush reached a critical latitude. These latitudes were 76°, 74° and 78°, respectively, for an average of 76° ± 2°. Applying the above conclusions to Cycle 24 is difficult due to the unusual nature of this cycle. Cycle 24 displays an intermittent "Rush" that is only well-defined in the northern hemisphere. In 2009 an initial slope of 4.6°/yr was found in the north, compared to an average of 9.4 ± 1.7 °/yr in the previous three cycles. This early fit to the Rush would have reached 76° at 2014.6. However, in 2010 the slope increased to 7.5°/yr (an increase

  16. Sources of solar wind over the solar activity cycle

    PubMed Central

    Poletto, Giannina

    2012-01-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review. PMID:25685421

  17. Sources of solar wind over the solar activity cycle.

    PubMed

    Poletto, Giannina

    2013-05-01

    Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as well. Slow wind observed in situ can be traced back to its solar source by backward extrapolation of magnetic fields whose field lines are streamlines of the outflowing plasma. However, this technique often has not the necessary precision for an indisputable identification of the region where wind originates. As the Sun progresses through its activity cycle, different wind sources prevail and contribute to filling the heliosphere. Our present knowledge of different wind sources is here summarized. Also, a Section addresses the problem of wind acceleration in the low corona, as inferred from an analysis of UV data, and illustrates changes between fast and slow wind profiles and possible signatures of changes along the solar cycle. A brief reference to recent work about the deep roots of solar wind and their changes over different solar cycles concludes the review.

  18. The solar UV related changes in total ozone from a solar rotation to a solar cycle

    SciTech Connect

    Chandra, S.

    1991-05-01

    The Nimbus-7 TOMS version 6 data, corrected for the instrument degradation, are analyzed to delineate the solar UV related changes in total ozone (TOZ) against background signals of dynamical origin. It is shown that the solar UV related change in TOZ over a solar cycle is about 1.5 percent that may be attributed to about 6 percent change in the solar UV flux near 200 nm. This estimate is also consistent with the solar UV related changes in TOZ over a time scale of a solar rotation. In the solar rotation case, ozone lags the solar UV by 3-4 days and its sensitivity to solar UV change is a factor of 203 less than for the solar cycle case. Both these effects are attributed to chemical time constants in the lower stratosphere that are comparable to the period of a solar rotation.

  19. The solar UV related changes in total ozone from a solar rotation to a solar cycle

    NASA Technical Reports Server (NTRS)

    Chandra, S.

    1991-01-01

    The Nimbus-7 TOMS version 6 data, corrected for the instrument degradation, are analyzed to delineate the solar UV related changes in total ozone (TOZ) against background signals of dynamical origin. It is shown that the solar UV related change in TOZ over a solar cycle is about 1.5 percent that may be attributed to about 6 percent change in the solar UV flux near 200 nm. This estimate is also consistent with the solar UV related changes in TOZ over a time scale of a solar rotation. In the solar rotation case, ozone lags the solar UV by 3-4 days and its sensitivity to solar UV change is a factor of 2-3 less than for the solar cycle case. Both these effects are attributed to chemical time constants in the lower stratosphere that are comparable to the period of a solar rotation.

  20. Study of the Solar Cycle from Space

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The objectives of and benefits to be derived from a program of solar cycle research are discussed with emphasis on the role space observations will play in this venture. The strategy to be employed in the coming decade is considered as well as crucial missions, experiments, and the theoretical advances required.

  1. Solar Cycle 23 in Coronal Bright Points

    NASA Astrophysics Data System (ADS)

    Sattarov, Isroil; Pevtsov, Alexei A.; Karachik, Nina V.; Sherdanov, Chori T.; Tillaboev, A. M.

    2010-04-01

    We describe an automatic routine to identify coronal bright points (CBPs) and apply this routine to SOHO/EIT observations taken in the 195 Å spectral range during solar cycle 23. We examine the total number of CBPs and its change in the course of this solar cycle. Unlike some other recent studies, we do find a modest ≈30% decrease in the number of CBPs associated with maximum of sunspot activity. Using the maximum brightness of CBPs as a criterion, we separate them on two categories: dim CBPs, associated with areas of a quiet Sun, and bright CBPs, associated with an active Sun. We find that the number of dim coronal bright points decreases at the maximum of sunspot cycle, while the number of bright CBPs increases. The latitudinal distributions suggest that dim CBPs are distributed uniformly over the solar disk. Active Sun CBPs exhibit a well-defined two-hump latitudinal profile suggestive of enhanced production of this type of CBPs in sunspot activity belts. Finally, we investigate the relative role of two mechanisms in cycle variations of CBP number, and conclude that a change in fraction of solar surface occupied by the quiet Sun’s magnetic field is the primary cause, with the visibility effect playing a secondary role.

  2. Geomagnetism during solar cycle 23: Characteristics.

    PubMed

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2013-05-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996-2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum.

  3. Geomagnetism during solar cycle 23: Characteristics

    PubMed Central

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2012-01-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum. PMID:25685427

  4. Influence of Solar Cycles on Earthquakes

    NASA Astrophysics Data System (ADS)

    Tavares, M.

    2011-12-01

    This research inspects possible influence of solar cycles on earthquakes through of statistical analyses. We also discussed the mechanism that would drive the occurrence of increasing of earthquakes during solar maxima. The study was based on worldwide earthquakes events during approximately four hundred years (1600-2010). The increase of earthquakes events followed the Maxima of Solar cycle, and also depends on the tectonic plate location. From 1600 until 1645 events increased during the Maxima in some of the tectonic plates as Pacific, Arabian and South America. The earthquakes analyzed during two grand solar minima, the Maunder (1645-1720) and the Dalton (1790-1820) showed a decrease in the number of earthquakes and the solar activity. It was observed during these minima a significant number of events at specific geological features. After the last minima (Dalton) the earthquakes pattern increased with solar maxima. The calculations showed that events increasing during solar maxima most in the Pacific, South America or Arabian until 1900. Since there were few records during these three centuries we needed additional analysis on modern data. We took the last four solar cycles events (1950-2010) and made similar calculations. The results agreed with the former calculations. It might be that the mechanism for the Sun-Earth connection relies on the solar wind speed. In both records (1600-1900) and (1950-2010) the results showed a significant increase in earthquakes events in some of the tectonic plates linked to solar maxima. The Solar wind energy striking the Earth's magnetosphere affects the entire environment because the pressure on the region increases and the magnetosphere shrinks sometimes four Earth's radii. This sudden compression causes earthquakes in specific plates. During the times of solar minima the pressure from the solar wind on the earth decreases, then the magnetosphere expands and earthquakes happen in a different pattern according to the

  5. Properties of solar activity and ionosphere for solar cycle 25

    NASA Astrophysics Data System (ADS)

    Deminov, M. G.; Nepomnyashchaya, E. V.; Obridko, V. N.

    2016-11-01

    Based on the known forecast of solar cycle 25 amplitude ( Rz max ≈ 50), the first assessments of the shape and amplitude of this cycle in the index of solar activity F10.7 (the magnitude of solar radio flux at the 10.7 cm wavelength) are given. It has been found that ( F10.7)max ≈ 115, which means that it is the lowest solar cycle ever encountered in the history of regular ionospheric measurements. For this reason, many ionospheric parameters for cycle 25, including the F2-layer peak height and critical frequency ( hmF2 and foF2), will be extremely low. For example, at middle latitudes, typical foF2 values will not exceed 8-10 MHz, which makes ionospheric heating ineffective in the area of upper hybrid resonance at frequencies higher than 10 MHz. The density of the atmosphere will also be extremely low, which significantly extends the lifetime of low-orbit satellites. The probability of F-spread will be increased, especially during night hours.

  6. If We Can't Predict Solar Cycle 24, What About Solar Cycle 34?

    NASA Technical Reports Server (NTRS)

    Pesnell. William Dean

    2008-01-01

    Predictions of solar activity in Solar Cycle 24 range from 50% larger than SC 23 to the onset of a Grand Minimum. Because low levels of solar activity are associated with global cooling in paleoclimate and isotopic records, anticipating these extremes is required in any longterm extrapolation of climate variability. Climate models often look forward 100 or more years, which would mean 10 solar cycles into the future. Predictions of solar activity are derived from a number of methods, most of which, such as climatology and physics-based models, will be familiar to atmospheric scientists. More than 50 predictions of the maximum amplitude of SC 24 published before solar minimum will be discussed. Descriptions of several methods that result in the extreme predictions and some anticipation of even longer term predictions will be presented.

  7. Study of solar activity and cosmic ray modulation during solar cycle 24 in comparison to previous solar cycle

    NASA Astrophysics Data System (ADS)

    Mishra, V. K.; Mishra, A. P.

    2016-12-01

    Based on the monthly data of sunspot numbers (SSN), sunspot area of full disc (SSA) and cosmic ray intensity (CRI) observed by neutron monitors (NM) located at Oulu (Cut off Rigidity = 0.8 GV) and Moscow (Cut off Rigidity = 2.3 GV), the trend of solar activity variation and cosmic ray modulation has been studied during the cycles 23 & 24. The SSN have maintained its minimum level exceptionally for a long period (July 2008-Aug. 2009) of time. The intensity of galactic cosmic rays measured by ground based detectors is the highest ever recorded by Oulu NM since April 1964 during the recent solar minimum. Furthermore, the maximum value of SSN is found to be very low in the present cycle in comparison to previous solar cycles (19-23). The correlation coefficient between SSN and CRI without and with time-lag as well as regression analysis during the solar cycle 24 (Jan. 2008-Dec. 2015) has been estimated and compared with previous solar cycle. Based on the maximum value of correlation coefficient, the time-lag during present solar cycle is found to be 4 and 10 months for both the stations, while it is 13-14 months during cycle 23. The behaviour of running cross correlation function has also been examined during present solar cycle and it is found that it attains its maximum value -0.8 to -0.9 for a long duration in comparison to previous cycles. The variation of SSN and SSA has also been compared and found that they are highly correlated to each other (r > .92) for both the cycles. In the light of exceptional behaviour of solar cycle 24, the trend of cosmic ray modulation has been discussed and compared with earlier cycles.

  8. On the possible relations between solar activities and global seismicity in the solar cycle 20 to 23

    SciTech Connect

    Herdiwijaya, Dhani; Arif, Johan; Nurzaman, Muhamad Zamzam; Astuti, Isna Kusuma Dewi

    2015-09-30

    Solar activities consist of high energetic particle streams, electromagnetic radiation, magnetic and orbital gravitational forces. The well-know solar activity main indicator is the existence of sunspot which has mean variation in 11 years, named by solar cycle, allow for the above fluctuations. Solar activities are also related to the space weather affecting all planetary atmospheric variability, moreover to the Earth’s climate variability. Large extreme space and geophysical events (high magnitude earthquakes, explosive volcanic eruptions, magnetic storms, etc.) are hazards for humankind, infrastructure, economies, technology and the activities of civilization. With a growing world population, and with modern reliance on delicate technological systems, human society is becoming increasingly vulnerable to natural hazardous events. The big question arises to the relation between solar forcing energy to the Earth’s global seismic activities. Estimates are needed for the long term occurrence-rate probabilities of these extreme natural hazardous events. We studied connectivity from yearly seismic activities that refer to and sunspot number within the solar cycle 20 to 23 of year 1960 to 2013 (53 years). We found clear evidences that in general high magnitude earthquake events and their depth were related to the low solar activity.

  9. Solar cycle variations of magnetopause locations

    NASA Astrophysics Data System (ADS)

    Němeček, Z.; Šafránková, J.; Lopez, R. E.; Dušík, Š.; Nouzák, L.; Přech, L.; Šimůnek, J.; Shue, J.-H.

    2016-07-01

    The magnetopause location is generally believed to be determined by the solar wind dynamic pressure and by the sign and value of the interplanetary magnetic field vertical (BZ) component. The contribution of other parameters is usually considered to be minor or negligible near the equatorial plane. Recent papers have shown a magnetopause expansion during intervals of a nearly radial IMF but our ability to predict the magnetopause location under steady or slowly changing upstream conditions remains rather weak even if the effect of radial magnetic field is considered. We present a statistical study based on more than 10,000 magnetopause crossings identified in the THEMIS data in the course of the last half of the solar cycle. The observed magnetopause locations are compared with an empirical magnetopause model of Shue et al. (1997) and the sources of differences between observations and model predictions are analyzed. This analysis reveals that the magnetopause location depends on the solar activity being more compressed during the solar maximum. Furthermore, we have found that, beside the solar wind dynamic pressure and vertical magnetic field component, the solar wind speed and ionospheric conductivity (F10.7 used as a proxy) are important physical quantities controlling this compression.

  10. A thermodynamic cycle for the solar cell

    NASA Astrophysics Data System (ADS)

    Alicki, Robert; Gelbwaser-Klimovsky, David; Jenkins, Alejandro

    2017-03-01

    A solar cell is a heat engine, but textbook treatments are not wholly satisfactory from a thermodynamic standpoint, since they present solar cells as directly converting the energy of light into electricity, and the current in the circuit as maintained by an electrostatic potential. We propose a thermodynamic cycle in which the gas of electrons in the p phase serves as the working substance. The interface between the p and n phases acts as a self-oscillating piston that modulates the absorption of heat from the photons so that it may perform a net positive work during a complete cycle of its motion, in accordance with the laws of thermodynamics. We draw a simple hydrodynamical analogy between this model and the ;putt-putt; engine of toy boats, in which the interface between the water's liquid and gas phases serves as the piston. We point out some testable consequences of this model.

  11. Dynamics of solar wind speed: Cycle 23

    NASA Astrophysics Data System (ADS)

    Sarkar, Tushnik; Khondekar, Mofazzal H.; Banerjee, Subrata

    2017-04-01

    A statistical signal processing approach has been made to study the dynamics of the speed of steady flow of hot plasma from the corona of sun known as solar wind generated in Solar Cycle 23. A long time series of solar wind speed of length 2492 days from 1st Jan, 1997 to 28th October, 2003 collected from Coordinated Heliospheric Observations (COHO) data base at NASA's National Space Science Data Center (NSSDC) is investigated for this purpose. Detection of nonlinearity and chaos in dynamics of solar wind speed is the prime objective of this work. In the present analysis delay vector variance (DVV) method is used to detect the existence of nonlinearity within the dynamics of solar wind speed. To explore the signature of the chaos in it multiple statistical methodologies like '0-1' test, the correlation dimension analysis, computation of Information Entropy of the time series and Largest Lyapunov Exponent method have been applied. It has been observed that though the coronal plasma i.e. solar wind flow rate has a nonlinear dynamics but without any chaos. The absence of chaos indicates a probable regular behaviour of the series. The unit magnitude of the Correlation dimension indicates the presence of the deterministic component of the series. Embedding Dimension obtained argues that the deterministic component has dimension of six. The nearly zero value of the Lyapunov exponent claims that the system is conservative and exhibits Lyapunov stability. These revelations establish that not only the solar wind speed alone but the solar wind-magnetosphere coupling is also contributing towards the complexity of the magnetospheric plasma dynamics.

  12. Geomagnetic activity during 10 - 11 solar cycles that has been observed by old Russian observatories.

    NASA Astrophysics Data System (ADS)

    Seredyn, Tomasz; Wysokinski, Arkadiusz; Kobylinski, Zbigniew; Bialy, Jerzy

    2016-07-01

    A good knowledge of solar-terrestrial relations during past solar activity cycles could give the appropriate tools for a correct space weather forecast. The paper focuses on the analysis of the historical collections of the ground based magnetic observations and their operational indices from the period of two sunspot solar cycles 10 - 11, period 1856 - 1878 (Bartels rotations 324 - 635). We use hourly observations of H and D geomagnetic field components registered at Russian stations: St. Petersburg - Pavlovsk, Barnaul, Ekaterinburg, Nertshinsk, Sitka, and compare them to the data obtained from the Helsinki observatory. We compare directly these records and also calculated from the data of the every above mentioned station IHV indices introduced by Svalgaard (2003), which have been used for further comparisons in epochs of assumed different polarity of the heliospheric magnetic field. We used also local index C9 derived by Zosimovich (1981) from St. Petersburg - Pavlovsk data. Solar activity is represented by sunspot numbers. The correlative and continuous wavelet analyses are applied for estimation of the correctness of records from different magnetic stations. We have specially regard to magnetic storms in the investigated period and the special Carrington event of 1-2 Sep 1859. Generally studied magnetic time series correctly show variability of the geomagnetic activity. Geomagnetic activity presents some delay in relation to solar one as it is seen especially during descending and minimum phase of the even 11-year cycle. This pattern looks similarly in the case of 16 - 17 solar cycles.

  13. CHARACTERISTICS OF SOLAR MERIDIONAL FLOWS DURING SOLAR CYCLE 23

    SciTech Connect

    Basu, Sarbani; Antia, H. M. E-mail: antia@tifr.res.i

    2010-07-01

    We have analyzed available full-disk data from the Michelson Doppler Imager on board SOHO using the 'ring diagram' technique to determine the behavior of solar meridional flows over solar cycle 23 in the outer 2% of the solar radius. We find that the dominant component of meridional flows during solar maximum was much lower than that during the minima at the beginning of cycles 23 and 24. There were differences in the flow velocities even between the two minima. The meridional flows show a migrating pattern with higher-velocity flows migrating toward the equator as activity increases. Additionally, we find that the migrating pattern of the meridional flow matches those of sunspot butterfly diagram and the zonal flows in the shallow layers. A high-latitude band in meridional flow appears around 2004, well before the current activity minimum. A Legendre polynomial decomposition of the meridional flows shows that the latitudinal pattern of the flow was also different during the maximum as compared to that during the two minima. The different components of the flow have different time dependences, and the dependence is different at different depths.

  14. On the seat of the solar cycle

    NASA Technical Reports Server (NTRS)

    Gough, D.

    1981-01-01

    A discussion of some of the issues raised in connection with the seat of the solar cycle are presented. Is the cycle controlled by a strictly periodic oscillator that operates in the core, or is it a turbulent dynamo confined to the convection zone and possibly a thin boundary layer beneath it? Sunspot statistics are discussed, with a view to ascertaining the length of the memory of the cycle, without drawing a definitive conclusion. Also discussed are some of the processes that might bring about variations delta L and delta R in the luminosity and the radius of the photosphere. It appears that the ratio W = delta lnR/delta lnL increases with the depth of the disturbance that produces the variations, so that imminent observations might determine whether or not the principal dynamical processes are confined to only the outer layers of the Sun.

  15. Solar cycle variations of thermospheric composition at the solstices

    NASA Astrophysics Data System (ADS)

    Qian, Liying; Burns, Alan G.; Solomon, Stanley C.; Wang, Wenbin; Zhang, Yongliang

    2016-04-01

    We examine the solar cycle variability of thermospheric composition (O/N2) at the solstices. Our observational and modeling studies show that the summer-to-winter latitudinal gradient of O/N2 is small at solar minimum but large at solar maximum; O/N2 is larger at solar maximum than at solar minimum on a global-mean basis; there is a seasonal asymmetry in the solar cycle variability of O/N2, with large solar cycle variations in the winter hemisphere and small solar cycle variations in the summer hemisphere. Model analysis reveals that vertical winds decrease the temperature-driven solar cycle variability in the vertical gradient of O/N2 in the summer hemisphere but increase it in the winter hemisphere; consequently, the vertical gradient of O/N2 does not change much in the summer hemisphere over a solar cycle, but it increases greatly from solar minimum to solar maximum in the winter hemisphere; this seasonal asymmetry in the solar cycle variability in the vertical gradient of O/N2 causes a seasonal asymmetry in the vertical advection of O/N2, with small solar cycle variability in the summer hemisphere and large variability in the winter hemisphere, which in turn drives the observed seasonal asymmetry in the solar cycle variability of O/N2. Since the equatorial ionization anomaly suppresses upwelling in the summer hemisphere and strengthens downwelling in the winter hemisphere through plasma-neutral collisional heating and ion drag, locations and relative magnitudes of the equatorial ionization anomaly crests and their solar cycle variabilities can significantly impact the summer-to-winter gradients of O/N2 and their solar cycle variability.

  16. Solar origins of solar wind properties during the cycle 23 solar minimum and rising phase of cycle 24.

    PubMed

    Luhmann, Janet G; Petrie, Gordon; Riley, Pete

    2013-05-01

    The solar wind was originally envisioned using a simple dipolar corona/polar coronal hole sources picture, but modern observations and models, together with the recent unusual solar cycle minimum, have demonstrated the limitations of this picture. The solar surface fields in both polar and low-to-mid-latitude active region zones routinely produce coronal magnetic fields and related solar wind sources much more complex than a dipole. This makes low-to-mid latitude coronal holes and their associated streamer boundaries major contributors to what is observed in the ecliptic and affects the Earth. In this paper we use magnetogram-based coronal field models to describe the conditions that prevailed in the corona from the decline of cycle 23 into the rising phase of cycle 24. The results emphasize the need for adopting new views of what is 'typical' solar wind, even when the Sun is relatively inactive.

  17. Solar neutrinos, solar flares, solar activity cycle and the proton decay

    NASA Technical Reports Server (NTRS)

    Raychaudhuri, P.

    1985-01-01

    It is shown that there may be a correlation between the galactic cosmic rays and the solar neutrino data, but it appears that the neutrino flux which may be generated during the large solar cosmic ray events cannot in any way effect the solar neutrino data in Davis experiment. Only initial stage of mixing between the solar core and solar outer layers after the sunspot maximum in the solar activity cycle can explain the higher (run number 27 and 71) of solar neutrino data in Davis experiment. But solar flare induced atmospheric neutrino flux may have effect in the nucleon decay detector on the underground. The neutrino flux from solar cosmic rays may be a useful guide to understand the background of nucleon decay, magnetic monopole search, and the detection of neutrino flux in sea water experiment.

  18. Brayton cycle solarized advanced gas turbine

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Described is the development of a Brayton Engine/Generator Set for solar thermal to electrical power conversion, authorized under DOE/NASA Contract DEN3-181. The objective was to design, fabricate, assemble, and test a small, hybrid, 20-kW Brayton-engine-powered generator set. The latter, called a power conversion assembly (PCA), is designed to operate with solar energy obtained from a parobolic dish concentrator, 11 meters in diameter, or with fossil energy supplied by burning fuels in a combustor, or by a combination of both (hybrid model). The CPA consists of the Brayton cycle engine, a solar collector, a belt-driven 20-kW generator, and the necessary control systems for automatic operation in solar-only, fuel-only, and hybrid modes to supply electrical power to a utility grid. The original configuration of the generator set used the GTEC Model GTP36-51 gas turbine engine for the PCA prime mover. However, subsequent development of the GTEC Model AGT101 led to its selection as the powersource for the PCA. Performance characteristics of the latter, thermally coupled to a solar collector for operation in the solar mode, are presented. The PCA was successfully demonstrated in the fuel-only mode at the GTEC Phoenix, Arizona, facilities prior to its shipment to Sandia National Laboratory in Albuquerque, New Mexico, for installation and testing on a test bed concentractor (parabolic dish). Considerations relative to Brayton-engine development using the all-ceramic AGT101 when it becomes available, which would satisfy the DOE heat engine efficiency goal of 35 to 41 percent, are also discussed in the report.

  19. Major Geomagnetic Storms in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Zheng, Y.

    2013-12-01

    Solar Cycle 24 has produced 11 major geomagnetic storms (where Dstmin < -100 nT) with three in 2011, six in 2012 and two in 2013 (as of 7 August 2013). Detailed analysis of each event will be given in terms of its solar driver(s): CME, coronal hole high speed solar wind stream (HSS), multiple CMEs or interactions between CME and HSS. While some of these storms are associated with a fast and wide CME, the few cases involving slow or common CMEs and interactions with HSS are particularly interesting. These events pose great challenges for accurate space weather forecasting, since operationally the slower or average CMEs tend to receive less attention and are sometimes overlooked altogether. The characteristics of such challenging, not-so-fast yet geoeffective CME events (such as their coronal signatures and interactions with surrounding solar wind structure(s), etc) will be examined in detail, with the goal of extracting common and telltale features, if any, of these CMEs that distinguish them from CMEs in a similar category.

  20. An Improved Solar Cycle Statistical Model for the Projection of Near Future Sunspot Cycles

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Wilson, John W.; Cucinotta, Francis A.

    2004-01-01

    Since the current solar cycle 23 has progressed near the end of the cycle and accurate solar minimum and maximum occurrences have been defined, a statistical model based on the odd-even behavior of historical sunspot cycles was reexamined. Separate calculations of activity levels were made for the rising and declining phases in solar cycle 23, which resulted in improved projection of sunspots in the remainder of cycle 23. Because a fundamental understanding of the transition from cycle to cycle has not been developed, at this time it is assumed for projection purposes that solar cycle 24 will continue at the same activity level in the declining phase of cycle 23. Projection errors in solar cycle 24 can be corrected as the cycle progresses and observations become available because this model is shown to be self-correcting.

  1. Solar cycle variation of magnetic flux emergence

    NASA Technical Reports Server (NTRS)

    Davis, J. M.; Golub, L.; Kreiger, A. S.

    1977-01-01

    The number of X-ray bright points (XBP) has been measured from solar X-ray images obtained during two rocket flights in 1976. When compared with the data obtained during the Skylab mission (1973), the number is found to be higher by a factor of 2. As the probability of obtaining the result by chance is less than 1 in 5 million, it is concluded that the number of XBP has increased in the three year interval. As all other indicators of activity have decreased between 1973 and 1976, the cyclical variation of the short-lifetime end of the magnetic-flux-emergence spectrum is out of phase with the solar cycle as defined by active regions or sunspots. Since XBP in 1973 contributed more to the emerging magnetic flux than did active regions, the possibility exists that the total amount of emerging magnetic flux may be maximized at a sunspot minimum.

  2. SUN-LIKE MAGNETIC CYCLES IN THE RAPIDLY ROTATING YOUNG SOLAR ANALOG HD 30495

    SciTech Connect

    Egeland, Ricky; Metcalfe, Travis S.; Hall, Jeffrey C.; Henry, Gregory W.

    2015-10-10

    A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar activity proxies exhibit a quasi-biennial (∼2 year) variation, which is superimposed upon the dominant 11 year cycle. A well-characterized stellar sample suggests at least two different relationships between rotation period and cycle period, with some stars exhibiting long and short cycles simultaneously. Within this sample, the solar cycle periods are typical of a more rapidly rotating star, implying that the Sun might be in a transitional state or that it has an unusual evolutionary history. In this work, we present new and archival observations of dual magnetic cycles in the young solar analog HD 30495, a ∼1 Gyr old G1.5 V star with a rotation period near 11 days. This star falls squarely on the relationships established by the broader stellar sample, with short-period variations at ∼1.7 years and a long cycle of ∼12 years. We measure three individual long-period cycles and find durations ranging from 9.6 to 15.5 years. We find the short-term variability to be intermittent, but present throughout the majority of the time series, though its occurrence and amplitude are uncorrelated with the longer cycle. These essentially solar-like variations occur in a Sun-like star with more rapid rotation, though surface differential rotation measurements leave open the possibility of a solar equivalence.

  3. Sun-like Magnetic Cycles in the Rapidly-rotating Young Solar Analog HD 30495

    NASA Astrophysics Data System (ADS)

    Egeland, Ricky; Metcalfe, Travis S.; Hall, Jeffrey C.; Henry, Gregory W.

    2015-10-01

    A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar activity proxies exhibit a quasi-biennial (∼2 year) variation, which is superimposed upon the dominant 11 year cycle. A well-characterized stellar sample suggests at least two different relationships between rotation period and cycle period, with some stars exhibiting long and short cycles simultaneously. Within this sample, the solar cycle periods are typical of a more rapidly rotating star, implying that the Sun might be in a transitional state or that it has an unusual evolutionary history. In this work, we present new and archival observations of dual magnetic cycles in the young solar analog HD 30495, a ∼1 Gyr old G1.5 V star with a rotation period near 11 days. This star falls squarely on the relationships established by the broader stellar sample, with short-period variations at ∼1.7 years and a long cycle of ∼12 years. We measure three individual long-period cycles and find durations ranging from 9.6 to 15.5 years. We find the short-term variability to be intermittent, but present throughout the majority of the time series, though its occurrence and amplitude are uncorrelated with the longer cycle. These essentially solar-like variations occur in a Sun-like star with more rapid rotation, though surface differential rotation measurements leave open the possibility of a solar equivalence.

  4. Deep space telecommunications and the solar cycle: A reappraisal

    NASA Technical Reports Server (NTRS)

    Berman, A. L.

    1978-01-01

    Observations of density enhancement in the near corona at solar cycle (sunspot) maximum have rather uncritically been interpreted to apply equally well to the extended corona, thus generating concern about the quality of outer planet navigational data at solar cycle maximum. Spacecraft have been deployed almost continuously during the recently completed solar cycle 20, providing two powerful new coronal investigatory data sources: (1) in-situ spacecraft plasma measurements at approximately 1 AU, and (2) plasma effects on monochromatic spacecraft signals at all signal closest approach points. A comprehensive review of these (solar cycle 20) data lead to the somewhat surprising conclusions that for the region of interest of navigational data, the highest levels of charged particle corruption of navigational data can be expected to occur at solar cycle minimum, rather than solar cycle maximum, as previously believed.

  5. Asymmetric behavior of different solar activity features over solar cycles 20-23

    NASA Astrophysics Data System (ADS)

    Bankoti, Neeraj Singh; Joshi, Navin Chandra; Pande, Bimal; Pande, Seema; Uddin, Wahab; Pandey, Kavita

    2011-07-01

    This paper presents the study of normalized north-south asymmetry, cumulative normalized north-south asymmetry and cumulative difference indices of sunspot areas, solar active prominences (at total, low (⩽40°) and high (⩾50°) latitudes) and H α solar flares from 1964 to 2008 spanning the solar cycles 20-23. Three different statistical methods are used to obtain the asymmetric behavior of different solar activity features. Hemispherical distribution of activity features shows the dominance of activities in northern hemisphere for solar cycle 20 and in southern hemisphere for solar cycles 21-23 excluding solar active prominences at high latitudes. Cumulative difference index of solar activity features in each solar cycle is observed at the maximum of the respective solar cycle suggesting a cyclic behavior of approximately one solar cycle length. Asymmetric behavior of all activity features except solar active prominences at high latitudes hints at the long term periodic trend of eight solar cycles. North-south asymmetries of SAP (H) express the specific behavior of solar activity at high solar latitudes and its behavior in long-time scale is distinctly opposite to those of other activity features. Our results show that in most cases the asymmetry is statistically highly significant meaning thereby that the asymmetries are real features in the N-S distribution of solar activity features.

  6. Variations of the solar wind and solar cycle in the last 300 years

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Silverman, S.

    1980-01-01

    The past history of the solar wind and solar cycle, inferred from records of geomagnetics and aurora, is examined. Records show that the solar wind apparently varied in a systematic manner throughout the period from 1770 to 1857 and that the period around 1810 resembled the 1901 minimum geomagnetic disturbance. Results show that the solar wind and hence the Sun changes on a time scale long compared to a solar cycle and short compared to the Maunder minimum. The inclusion of a study on the solar wind and solar cycle variations for the SCADM mission is discussed.

  7. Activity of the northern and southern hemispheres as a basis of the solar cycle manifestation

    NASA Astrophysics Data System (ADS)

    Ryabov, M. I.

    2015-12-01

    The dynamics of the evolution of solar cycles is considered a result of the activity manifestation in the northern and southern hemispheres. A study was performed based on separate datasets for the northern and southern hemispheres that contain the monthly and daily averages of the areas of sunspot groups for the period covering activity cycles from 12 to 24 (1874-2013) and the daily values of the Wolf number in the northern and southern hemispheres during cycles 23-24 (1992-2013).To obtain a pattern of development of the "northern" and "southern" solar cycles in detail, a special technique for the extended application of the wavelet analysis has been developed. It allows different the wave processes forming a solar cycle to be distinguished, together with the time of their existence. The application of bandpass Fourier filtering to the obtained data shows that the length of "11-year" cycles by the index S p varies from 10.2 to 11.5 years in the northern hemisphere and from 9.7 to 13.2 years in the southern. The 19th "northern" and 18th "southern" cycles turned out to be maximal. The formation of each of the cycles by all activity indices is determined by the joint effect of long-period processes lasting from 3 to 7 years and short-period processes lasting less than 2 years. When moving from one cycle to another, the long-period processes demonstrate mergings, separations, modulation, and periodic decays. The abnormal activity that appears during the growth, maximum, or decay phase of a cycle is formed at the expense of the simultaneous strengthening of short-period processes, the lengths and "period spectra" of which noticeably differ in the northern and southern hemispheres.

  8. Solar cycle length hypothesis appears to support the ipcc on global warming

    NASA Astrophysics Data System (ADS)

    Laut, P.; Gundermann, J.

    1998-12-01

    Since the discovery of a striking correlation between 1-2-2-2-1 filtered solar cycle lengths and the 11-year running average of northern hemisphere land air temperatures, there have been widespread speculations as to whether these findings would rule out any significant contributions to global warming from the enhanced concentrations of greenhouse gases. The solar hypothesis (as we shall term this assumption) claims that solar activity causes a significant component of the global mean temperature to vary in phase opposite to the filtered solar cycle lengths. In an earlier article we have demonstrated that for data covering the period 1860-1980 the solar hypothesis does not rule out any significant contribution from man-made greenhouse gases and sulphate aerosols. The present analysis goes a step further. We analyse the period 1579-1987 and find that the solar hypothesis-instead of contradicting-appears to support the assumption of a significant warming due to human activities. We have tentatively corrected the historical northern hemisphere land air temperature anomalies by removing the assumed effects of human activities. These are represented by northern hemisphere land air temperature anomalies calculated as the contributions from man-made greenhouse gases and sulphate aerosols by using an upwelling diffusion-energy balance model similar to the model of [Wigley and Raper, 1993] employed in the Second Assessment Report of The Intergovernmental Panel on Climate Change (IPCC). It turns out that the agreement of the filtered solar cycle lengths with the corrected temperature anomalies is substantially better than with the historical anomalies, with the mean square deviation reduced by 36% for a climate sensitivity of 2.5°C, the central value of the IPCC assessment, and by 43% for the best-fit value of 1.7°C. Therefore our findings support a total reversal of the common assumption that a verification of the solar hypothesis would challenge the IPCC assessment of

  9. Variability of Clouds Over a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2002-01-01

    One of the most controversial aspects of climate studies is the debate over the natural and anthropogenic causes of climate change. Historical data strongly suggest that the Little Ice Age (from 1550 to 1850 AD when the mean temperature was colder by about 1 C) was most likely caused by variability of the sun and not greenhouse molecules (e.g., CO2). However, the known variability in solar irradiance and modulation of cosmic rays provides too little energy, by many orders of magnitude, to lead to climate changes in the troposphere. The conjecture is that there is a 'trigger mechanism'. This idea may now be subjected to a quantitative test using recent global datasets. Using the best available modern cloud data from International Satellite Cloud Climatology Project (ISCCP), Svensmark and Friis-Christensen found a correlation of a large variation (3-4%) in global cloud cover with the solar cycle. The work has been extended by Svensmark and Marsh and Svensmark. The implied forcing on climate is an order of magnitude greater than any previous claims. Are clouds the long sought trigger mechanism? This discovery is potentially so important that it should be corroborated by an independent database, and, furthermore, it must be shown that alternative explanations (i.e., El Nino) can be ruled out. We used the ISCCP data in conjunction with the Total Ozone Mapping Spectrometer (TOMS) data to carry out in in depth study of the cloud trigger mechanism.

  10. Implications of the Deep Cycle 23/24 Minimum for our Understanding of the Solar Dynamo

    NASA Astrophysics Data System (ADS)

    Feynman, J.; Ruzmaikin, A.

    2011-12-01

    When the cycle 23/24 minimum is considered in the light of the existing record of 1,500 years of solar output proxies, it can be understood as a typical minimum of a periodic modulation of the amplitude of the 11-year solar cycle, which we call the Centennial Gleissberg Cycle (CGC). This 90-100 year amplitude variation has been well established by earlier studies (Gleissberg, 1965, Siscoe, 1980, Silverman and Feynman, 1980, Sonnett, 1982) and is present at least 80% of the time since 450 AD. It consists of a series of about nine or ten 11-year cycles with amplitudes that gradually rise and then fall (Feynman and Fougere, 1988). Previous well-established deep minima took place about 1710, 1810 (Dalton Minimum) and 1910. Because of this record a minimum about 2010 was not unexpected (e.g. Silverman, 1992). The CGC was also seen in auroral observations from 450 AD to 1450 AD. It thus appears that the magnetic field generated by the solar dynamo has a quasi-periodic variation of about 100 years, the cause of which demands future study. In this talk we will review the evidence that the peculiar behavior noticed during 23/24 minimum was a CGC minimum. We will describe the CGC and develop criteria to distinguish it from Grand Minima such as the Maunder Minimum. When these criteria are applied to the observations, the CGC hypothesis is clearly favored. We will discuss possible models of non-linear dynamos that can explain the origin of the CGC.

  11. Solar UV Variations During the Decline of Cycle 23

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew, T.; Cebula, Richard P.

    2011-01-01

    Characterization of temporal and spectral variations in solar ultraviolet irradiance over a solar cycle is essential for understanding the forcing of Earth's atmosphere and climate. Satellite measurements of solar UV variability for solar cycles 21, 22, and 23 show consistent solar cycle irradiance changes at key wavelengths (e.g. 205 nm, 250 nm) within instrumental uncertainties. All historical data sets also show the same relative spectral dependence for both short-term (rotational) and long-term (solar cycle) variations. Empirical solar irradiance models also produce long-term solar UV variations that agree well with observational data. Recent UV irradiance data from the Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instruments covering the declining phase of Cycle 23 present a different picture oflong-term solar variations from previous results. Time series of SIM and SOLSTICE spectral irradiance data between 2003 and 2007 show solar variations that greatly exceed both previous measurements and predicted irradiance changes over this period, and the spectral dependence of the SIM and SOLSTICE variations during these years do not show features expected from solar physics theory. The use of SORCE irradiance variations in atmospheric models yields substantially different middle atmosphere ozone responses in both magnitude and vertical structure. However, short-term solar variability derived from SIM and SOLSTICE UV irradiance data is consistent with concurrent solar UV measurements from other instruments, as well as previous results, suggesting no change in solar physics. Our analysis of short-term solar variability is much less sensitive to residual instrument response changes than the observations of long-term variations. The SORCE long-term UV results can be explained by under-correction of instrument response changes during the first few years of measurements

  12. 11-Year cyclicity of the near-surface heat flux at the Vostok station

    NASA Astrophysics Data System (ADS)

    Volobuev, D. M.

    2013-12-01

    It is known that the solar component is difficult to find in a climatic signal due to its small size and significant internal random disturbances of the climatic system, such as variations in cloudiness, precipitation, winds, and oceanic currents. In the center of the polar cap, these disturbances are as minimal as possible; therefore, solving the inverse heat conduction problem, we can calculate the informative heat flux through the ice cover based on temperature data. Variations in the heat flux are quite significant in amplitude (0.2-0.3 W/m2) and coincide with the 11-year solar cycle in phase. Application of this approach to the indices of the global and sea surface temperatures cannot yield a solar signal, yet it can be traced for solar cycles with big amplitude (cycles 19 and 21). Thus, the found variation in the heat flux is most probably caused by a change in the solar constant (TSI); however, other mechanisms are also possible.

  13. INTERNAL-CYCLE VARIATION OF SOLAR DIFFERENTIAL ROTATION

    SciTech Connect

    Li, K. J.; Xie, J. L.; Shi, X. J.

    2013-06-01

    The latitudinal distributions of the yearly mean rotation rates measured by Suzuki in 1998 and 2012 and Pulkkinen and Tuominen in 1998 are utilized to investigate internal-cycle variation of solar differential rotation. The rotation rate at the solar equator seems to have decreased since cycle 10 onward. The coefficient B of solar differential rotation, which represents the latitudinal gradient of rotation, is found to be smaller in the several years after the minimum of a solar cycle than in the several years after the maximum time of the cycle, and it peaks several years after the maximum time of the solar cycle. The internal-cycle variation of the solar rotation rates looks similar in profile to that of the coefficient B. A new explanation is proposed to address such a solar-cycle-related variation of the solar rotation rates. Weak magnetic fields may more effectively reflect differentiation at low latitudes with high rotation rates than at high latitudes with low rotation rates, and strong magnetic fields may more effectively repress differentiation at relatively low latitudes than at high latitudes. The internal-cycle variation is inferred as the result of both the latitudinal migration of the surface torsional pattern and the repression of strong magnetic activity in differentiation.

  14. Solar spectral irradiance variability in cycle 24: observations and models

    NASA Astrophysics Data System (ADS)

    Marchenko, Sergey V.; DeLand, Matthew T.; Lean, Judith L.

    2016-12-01

    Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265 and 500 nm during the ongoing cycle 24. We supplement the OMI data with concurrent observations from the Global Ozone Monitoring Experiment-2 (GOME-2) and Solar Radiation and Climate Experiment (SORCE) instruments and find fair-to-excellent, depending on wavelength, agreement among the observations, and predictions of the Naval Research Laboratory Solar Spectral Irradiance (NRLSSI2) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models.

  15. Predicting Solar Cycle 24 Using a Geomagnetic Precursor Pair

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean

    2014-01-01

    We describe using Ap and F(10.7) as a geomagnetic-precursor pair to predict the amplitude of Solar Cycle 24. The precursor is created by using F(10.7) to remove the direct solar-activity component of Ap. Four peaks are seen in the precursor function during the decline of Solar Cycle 23. A recurrence index that is generated by a local correlation of Ap is then used to determine which peak is the correct precursor. The earliest peak is the most prominent but coincides with high levels of non-recurrent solar activity associated with the intense solar activity of October and November 2003. The second and third peaks coincide with some recurrent activity on the Sun and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, which appears in early 2008 and has recurrent activity similar to precursors of earlier solar cycles, appears to be the "true" precursor peak for Solar Cycle 24 and predicts the smallest amplitude for Solar Cycle 24. To determine the timing of peak activity it is noted that the average time between the precursor peak and the following maximum is approximately equal to 6.4 years. Hence, Solar Cycle 24 would peak during 2014. Several effects contribute to the smaller prediction when compared with other geomagnetic-precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F(10.7) shows that F(10.7) is higher than the equivalent sunspot number over most of the cycle, implying that the sunspot number underestimates the solar-activity component described by F(10.7). During 2003 the correlation between aa and Ap shows that aa is 10 % higher than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. However, the most important difference is the lack of recurrent activity in the first three peaks and the presence of significant recurrent activity in the fourth. While the prediction is for an amplitude of Solar Cycle 24 of

  16. Hybrid solar central receiver for combined cycle power plant

    DOEpatents

    Bharathan, Desikan; Bohn, Mark S.; Williams, Thomas A.

    1995-01-01

    A hybrid combined cycle power plant including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production.

  17. Hybrid solar central receiver for combined cycle power plant

    DOEpatents

    Bharathan, D.; Bohn, M.S.; Williams, T.A.

    1995-05-23

    A hybrid combined cycle power plant is described including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production. 1 figure.

  18. Hepatoblastoma in an 11-year-old

    PubMed Central

    Pateva, Irina B.; Egler, Rachel A.; Stearns, Duncan S.

    2017-01-01

    Abstract Rationale: Hepatoblastoma is a rare malignancy. Approximately 100 cases are diagnosed yearly in the United States. The highest incidence occurs in infants and in children younger than 5 years. Cases involving patients older than 5 years are very rare. We describe the case of a patient who was diagnosed with hepatoblastoma at an atypical age of presentation for this type of malignancy. We also performed Ovid MEDLINE search for hepatoblastoma and epidemiology reports occurring in children between the ages of 5 and 18 years. In this article we review the epidemiology and summarize case reports published between 1997 and 2012 of patients with hepatoblastoma, who were older than 5 years. Patient concerns and diagnosis: Our patient is an 11 year old boy with stage IV hepatoblastoma with lung and omental metastases at diagnosis. Interventions: The patient received 7 cycles of chemotherapy following the treatment plan of COG protocol AHEP 0731, off study. He also had tumor resection and omentectomy and achieved complete remission. Outcomes: He later had disease recurrence and after undergoing treatment with different modalities, ultimately died of his disease. Review of SEER program data shows that the incidence of hepatoblastoma in children above the age of 5 years is too infrequent to be calculated. Literature review revealed 13 cases of patients diagnosed at age older than 5 years. Most cases were published due to unusual associations and/or complications. There are no obvious unifying characteristics for these cases, although there may be a slight male preponderance and many patients in this selected series presented with elevated Alpha-fetoprotein. Lessons: The reported case is rare, given the very low incidence of hepatoblastoma outside of infancy. A systematic review of characteristics and outcomes for patients older than 5 years who are enrolled in cooperative group hepatoblastoma trials may reveal important information about the epidemiology and tumor

  19. Major Space Weather Events during the Weak Solar Cycle 24

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2012-01-01

    We report on the level of solar activity during cycles 23 and 24 as the cycles build toward the corresponding solar maxima. The prolonged minimum period that followed solar cycle 23 and the weaker magnetic field at the poles seem to have resulted in a weaker level of activity during cycle 24. The double speak structure often observed in the maximum phases seems to be present during cycle 24, with the first peak having a sunspot number of only N90. large solar energetic particle (SEP) events, major geomagnetic storms, and radio-emitting interplanetary shocks have been observed in relatively sma:ier numbers. While the number of large SEP events during the rise phase of cycles 24 is not too different from that of cycle 23, they are generally less intense. Five ground level enhancement (GlE) events occurred up to the first activity peak in cycle 23, while a lone GlE event has been observed during the corresponding phase in cycle 24. There were 35 large (Dst S -100 nT) geomagnetic storms during the first 4.5 years of cycle 23, while only 5 occurred during cycle 24. The subdued activity during cycle 23 is consistent with the low numbers of type II radio bursts, full halo CMEs, and interplanetary shocks.

  20. A simple mechanistic model for the solar cycle modulation of winter Arctic ozone

    NASA Astrophysics Data System (ADS)

    Li, K.; Tung, K. K.

    2013-12-01

    Observational evidence shows that when the equatorial quasi-biennial oscillation (QBO) is in its easterly descending phase or when the 11-year solar cycle is in its solar maximum, or both, the winter Arctic stratosphere is anomalously warm by 5 K and the Arctic ozone is enhaced by 60 DU. For QBO, it has been known that the Holton-Tan effect, which modulates the planetary wave potential vorticity, weakens the polar vortex and eventually leads to enhanced isentropic mixing of the polar air with low latitude air. It has been suggested that similar teleconnection mechanism may be involved in the solar modulation of the polar stratosphere, but a defintive model study is lacking. In this study, a linear two-dimensional model for the residual Eulerian meridional circulation [Tung and Yang, 1994, J. Atmos. Sci., 51, 2708-2721] is employed. The QBO is forced by the equatorial Kelvin and Rossby waves and the solar cycle forcing is represented by the equatorial ozone heating. The mechanism through which the polar vortex is perturbed by the equatorial heating will be investigated.

  1. DMSP Auroral Charging at Solar Cycle 24 Maximum

    NASA Technical Reports Server (NTRS)

    Chandler, M.; Parker, L. Neergaard; Minow, J. I.

    2013-01-01

    It has been well established that polar orbiting satellites can experience mild to severe auroral charging levels (on the order of a few hundred volts to few kilovolts negative frame potentials) during solar minimum conditions. These same studies have shown a strong reduction in charging during the rising and declining phases of the past few solar cycles with a nearly complete suppression of auroral charging at solar maximum. Recently, we have observed examples of high level charging during the recent approach to Solar Cycle 24 solar maximum conditions not unlike those reported by Frooninckx and Sojka. These observations demonstrate that spacecraft operations during solar maximum cannot be considered safe from auroral charging when solar activity is low. We present a survey of auroral charging events experienced by the Defense Meteorological Satellite Program (DMSP) F16 satellite during Solar Cycle 24 maximum conditions. We summarize the auroral energetic particle environment and the conditions necessary for charging to occur in this environment, we describe how the lower than normal solar activity levels for Solar Cycle 24 maximum conditions are conducive to charging in polar orbits, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period.

  2. Search for relationship between duration of the extended solar cycles and amplitude of sunspot cycle

    NASA Astrophysics Data System (ADS)

    Tlatov, A. G.

    2007-12-01

    Duration of the extended solar cycles is taken into the consideration. The beginning of cycles is counted from the moment of polarity reversal of large-scale magnetic field in high latitudes, occurring in the sunspot cycle n till the minimum of the cycle n+2. The connection between cycle duration and its amplitude is established. Duration of the ``latent" period of evolution of extended cycle between reversals and a minimum of the current sunspot cycle is entered. It is shown, that the latent period of cycles evolution is connected with the next sunspot cycle amplitude and can be used for the prognosis of a level and time of a sunspot maximum. The 24th activity cycle prognosis is made. The found dependences correspond to transport dynamo model of generation of solar cyclicity, it is possible with various speed of meridional circulation. Long-term behavior of extended cycle's lengths and connection with change of a climate of the Earth is considered.%

  3. Development of Solar Activity Cycle 24: Some Comments

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.

    Our forecast for the development phase of the solar cycle 23 turned out to be right on the mark; one of the very few to have acquired this status out of nearly 40 forecasts made for cycle 23. This is the first time in the 400 year history of the sunspot observations that a forecast was made for a solar cycle, it was defended against a severe peer criticism and came out true. We review the details of our actual forcast and how they fared as the events unfolded during cycle 23. We then consider the present status of the solar wind, the geomagnetic planetary indices, and the recovery of the galactic cosmic rays from cycle 23 modulation. Next, we draw inferences as to what to expect for the development phase of solar cycle 24. We are aware that several forecasts have already been made for the development of solar cycle 24 activity. They cover all possible scenarios, ranging from the most active to the quietest ever cycle. Clearly, some of these forecasts are unlikely to materialize. We discuss emerging details of the physical link between the observations and the workings of the solar dynamo.

  4. COUPLING THE SOLAR DYNAMO AND THE CORONA: WIND PROPERTIES, MASS, AND MOMENTUM LOSSES DURING AN ACTIVITY CYCLE

    SciTech Connect

    Pinto, Rui F.; Brun, Allan Sacha; Grappin, Roland

    2011-08-20

    We study the connections between the Sun's convection zone and the evolution of the solar wind and corona. We let the magnetic fields generated by a 2.5-dimensional (2.5D) axisymmetric kinematic dynamo code (STELEM) evolve in a 2.5D axisymmetric coronal isothermal magnetohydrodynamic code (DIP). The computations cover an 11 year activity cycle. The solar wind's asymptotic velocity varies in latitude and in time in good agreement with the available observations. The magnetic polarity reversal happens at different paces at different coronal heights. Overall the Sun's mass-loss rate, momentum flux, and magnetic braking torque vary considerably throughout the cycle. This cyclic modulation is determined by the latitudinal distribution of the sources of open flux and solar wind and the geometry of the Alfven surface. Wind sources and braking torque application zones also vary accordingly.

  5. Simulation of the combined effects of solar cycle, quasi-biennial oscillation, and volcanic forcing on stratospheric ozone changes in recent decades

    NASA Astrophysics Data System (ADS)

    Lee, H.; Smith, A. K.

    2003-01-01

    Stratospheric ozone responses to the 11-year solar flux variation are calculated from two different decadal scale satellite ozone data sets by multiple regression analysis. The results show consistent dipole structures with solar regression coefficients that are positive in midlatitudes and negative in the equatorial lower stratospheric region. Because of the limited duration of the data record, the regression analysis may not completely separate variability from other processes. Other phenomena that could contribute to the observed pattern include the ozone variations associated with the quasi-biennial oscillation (QBO) and with two major volcanic eruptions: El Chichón in 1982 and Mount Pinatubo in 1991. A fully interactive NCAR two-dimensional chemical-dynamical-radiative model (Simulation of Chemistry, Radiation, and Transport of Environmentally Important Species (SOCRATES)) is used to investigate the effects of the equatorial QBO and the major volcanic eruptions on the 11-year solar cycle analysis. When both effects are considered in the model simulation, the resulting ozone solar signal shows a dipole pattern similar to that observed. When the 11-year solar flux variation is considered as the only external forcing, the resulting ozone solar cycle shows a monopole structure whose maximum is located in the equatorial upper stratosphere and whose response is uniformly positive.

  6. Forecasting the Peak of the Present Solar Activity Cycle

    NASA Astrophysics Data System (ADS)

    Hamid, Rabab; Marzouk, Beshir

    2016-07-01

    Solar forecasting of the level of sun Activity is very important subject for all space programs. Most predictions are based on the physical conditions prevailing at or before the solar cycle minimum preceding the maximum in question. Our aim is to predict the maximum peak of cycle 24 using precursor techniques in particular those using spotless event, geomagnetic aa min. index and solar flux F10.7. Also prediction of exact date of the maximum (Tr) is taken in consideration. A study of variation over previous spotless event for cycles 7-23 and that for even cycles (8-22) are carried out for the prediction. Linear correlation between RM and spotless event around the preceding minimum gives RM24t = 101.9with rise time Tr = 4.5 Y. For the even cycles RM24e = 108.3 with rise time Tr = 3.9 Y. Based on the average aa min. index for the year of sunspot minimum cycles (13 - 23), we estimate the expected amplitude for cycle 24 to be RMaa = 116.5 for both the total and even cycles. Application of the data of solar flux F10.7 which cover only cycles (19-23) was taken in consideration and gives predicted maximum amplitude R24 10.7 = 146, which are over estimation. Our result indicating a somewhat weaker cycle 24 as compared to cycles 21-23.

  7. 25 MeV Solar Proton Events in Cycle 24 and Previous Cycles

    NASA Astrophysics Data System (ADS)

    Richardson, I. G.; Cane, H. V.; von Rosenvinge, T. T.

    2014-12-01

    We summarize observations of nearly 1000 solar energetic particle events that include 25 MeV protons made by Goddard instruments on various spacecraft (IMPs IV, V, 7, 8, ISEE-3) and by other instruments on SOHO, since 1967, encompassing solar cycles 20 to 24. We also include recent observations of such events from the STEREO spacecraft. These extended observations place studies focusing on Cycles 23 and 24 in a broader context. For example, the time distribution of 25 MeV proton events varies from cycle to cycle such that each cycle is unique. In the current cycle, ~25 MeV proton events were absent during the preceding solar minimum, whereas earlier minima showed occasional, often reasonably intense events, and there have been, so far, fewer exceptionally intense events compared to Cycles 22 and 23, though Cycle 21 also apparently lacked such events.

  8. White-light corona and solar polar magnetic field strength over solar cycles

    NASA Astrophysics Data System (ADS)

    Rušin, V.; Saniga, M.; Komžík, R.

    2014-10-01

    We discuss the large-scale structure of the solar corona, in particular its helmet streamers, as observed during total solar eclipses around maxima of solar cycles and make its comparison with solar polar magnetic field strength as observed by the Wilcox Solar Observatory (WSO) since 1976. Even though the magnetic field strength at the solar poles around cycle minima decreased minimally twice in the last forty years, distributions of helmet streamers around the Sun in different cycles around cycle maxima remain nearly the same. This indicates that large-scale magnetic structures governing the shape and evolution of helmet streamers must be of a different nature than those related with solar polar fields.

  9. Special points in 11-year variations in the latitudinal characteristics of sunspot activity

    NASA Astrophysics Data System (ADS)

    Miletsky, E. V.; Nagovitsyn, Yu. A.

    2012-12-01

    It has been indicated that special moments (turning points), when certain characteristics of the latitudinal (equatorward) drift of the sunspot drift zone suddenly change, exist in each 11-year solar cycle. The moment when a sunspot formation low-latitude boundary minimum (T2), coordinated in time with the end of a polar magnetic field polarity reversal, exists has a special place among these points. A conclusion has been drawn that it is impossible to reconstruct polarity reversal moments in the past based on information about turning points T2. The average velocities of the latitudinal drift of the minimal, average, and maximal sunspot group latitudes have been calculated. It has been indicated that the closeness of the relationship between the first two velocities and the maximal activity amplitudes in the cycles differ substantially for the first (before point T2) and second (after point T2) cycle parts. The corresponding values of the correlation coefficients increase substantially in the second cycle (after point T2). It has been established that a relationship exists between some velocities calculated in these cycles and the activity amplitudes at maximums of the next cycles. A model for predicting future cycle maximums has been constructed based on this conclusion. The probable average annual Wolf number at a maximum of cycle 24 has been determined (W(24) = 93).

  10. Solar thermal organic rankine cycle for micro-generation

    NASA Astrophysics Data System (ADS)

    Alkahli, N. A.; Abdullah, H.; Darus, A. N.; Jalaludin, A. F.

    2012-06-01

    The conceptual design of an Organic Rankine Cycle (ORC) driven by solar thermal energy is developed for the decentralized production of electricity of up to 50 kW. Conventional Rankine Cycle uses water as the working fluid whereas ORC uses organic compound as the working fluid and it is particularly suitable for low temperature applications. The ORC and the solar collector will be sized according to the solar flux distribution in the Republic of Yemen for the required power output of 50 kW. This will be a micro power generation system that consists of two cycles, the solar thermal cycle that harness solar energy and the power cycle, which is the ORC that generates electricity. As for the solar thermal cycle, heat transfer fluid (HTF) circulates the cycle while absorbing thermal energy from the sun through a parabolic trough collector and then storing it in a thermal storage to increase system efficiency and maintains system operation during low radiation. The heat is then transferred to the organic fluid in the ORC via a heat exchanger. The organic fluids to be used and analyzed in the ORC are hydrocarbons R600a and R290.

  11. ANALYSIS OF SUNSPOT AREA OVER TWO SOLAR CYCLES

    SciTech Connect

    De Toma, G.; Chapman, G. A.; Preminger, D. G.; Cookson, A. M.

    2013-06-20

    We examine changes in sunspots and faculae and their effect on total solar irradiance during solar cycles 22 and 23 using photometric images from the San Fernando Observatory. We find important differences in the very large spots between the two cycles, both in their number and time of appearance. In particular, there is a noticeable lack of very large spots in cycle 23 with areas larger than 700 millionths of a solar hemisphere which corresponds to a decrease of about 40% relative to cycle 22. We do not find large differences in the frequencies of small to medium spots between the two cycles. There is a decrease in the number of pores and very small spots during the maximum phase of cycle 23 which is largely compensated by an increase during other phases of the solar cycle. The decrease of the very large spots, in spite of the fact that they represent only a few percent of all spots in a cycle, is primarily responsible for the observed changes in total sunspot area and total sunspot deficit during cycle 23 maximum. The cumulative effect of the decrease in the very small spots is an order of magnitude smaller than the decrease caused by the lack of large spots. These data demonstrate that the main difference between cycles 22 and 23 was in the frequency of very large spots and not in the very small spots, as previously concluded. Analysis of the USAF/NOAA and Debrecen sunspot areas confirms these findings.

  12. Analysis of Sunspot Area over Two Solar Cycles

    NASA Astrophysics Data System (ADS)

    de Toma, G.; Chapman, G. A.; Preminger, D. G.; Cookson, A. M.

    2013-06-01

    We examine changes in sunspots and faculae and their effect on total solar irradiance during solar cycles 22 and 23 using photometric images from the San Fernando Observatory. We find important differences in the very large spots between the two cycles, both in their number and time of appearance. In particular, there is a noticeable lack of very large spots in cycle 23 with areas larger than 700 millionths of a solar hemisphere which corresponds to a decrease of about 40% relative to cycle 22. We do not find large differences in the frequencies of small to medium spots between the two cycles. There is a decrease in the number of pores and very small spots during the maximum phase of cycle 23 which is largely compensated by an increase during other phases of the solar cycle. The decrease of the very large spots, in spite of the fact that they represent only a few percent of all spots in a cycle, is primarily responsible for the observed changes in total sunspot area and total sunspot deficit during cycle 23 maximum. The cumulative effect of the decrease in the very small spots is an order of magnitude smaller than the decrease caused by the lack of large spots. These data demonstrate that the main difference between cycles 22 and 23 was in the frequency of very large spots and not in the very small spots, as previously concluded. Analysis of the USAF/NOAA and Debrecen sunspot areas confirms these findings.

  13. Solar Cycle Characteristics and Their Relationship with Dynamo Theory

    NASA Astrophysics Data System (ADS)

    Otkidychev, P. A.; Popova, H.; Popov, V.

    2015-12-01

    We try to establish the correlation between different parameters of “butterfly-diagrams” derived from the analysis of solar observational data for the 12-23 solar activity cycles and the values in the models of α-Ω­dynamo using RGO - NASA/Marshall data set. We have ascertained that there is a linear relationship between S and BT/L for all the investigated cycles, where S is the mean area of the sunspots (umbrae), B is the mean magnetic field strength, T is duration of a cycle and L is the mean latitude of the sunspots in a cycle.

  14. Solar Cycle in the Heliosphere and Cosmic Rays

    DTIC Science & Technology

    2014-10-23

    information if it does not display a currently valid OMB control number. 1. REPORT DATE 23 OCT 2014 2. REPORT TYPE N/A 3. DATES COVERED 4...cycle, varying from nearly no spots at solar minimum to high values of about 200 at solar maximum. To date , current cycle No. 24 which started in December...cycle 19–24 (see Table 1 for dates ). These are shown in 12-month increments starting with the year after the sunspot minimum for each cycle. Only the

  15. Data Assimilation Approach for Forecast of Solar Activity Cycles

    NASA Astrophysics Data System (ADS)

    Kitiashvili, Irina N.

    2016-11-01

    Numerous attempts to predict future solar cycles are mostly based on empirical relations derived from observations of previous cycles, and they yield a wide range of predicted strengths and durations of the cycles. Results obtained with current dynamo models also deviate strongly from each other, thus raising questions about criteria to quantify the reliability of such predictions. The primary difficulties in modeling future solar activity are shortcomings of both the dynamo models and observations that do not allow us to determine the current and past states of the global solar magnetic structure and its dynamics. Data assimilation is a relatively new approach to develop physics-based predictions and estimate their uncertainties in situations where the physical properties of a system are not well-known. This paper presents an application of the ensemble Kalman filter method for modeling and prediction of solar cycles through use of a low-order nonlinear dynamo model that includes the essential physics and can describe general properties of the sunspot cycles. Despite the simplicity of this model, the data assimilation approach provides reasonable estimates for the strengths of future solar cycles. In particular, the prediction of Cycle 24 calculated and published in 2008 is so far holding up quite well. In this paper, I will present my first attempt to predict Cycle 25 using the data assimilation approach, and discuss the uncertainties of that prediction.

  16. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    NASA Astrophysics Data System (ADS)

    Stolarski, R. S.; Swartz, W. H.; Jackman, C. H.; Fleming, E. L.

    2011-12-01

    Recent measurements from the SIM instrument on the SORCE satellite have been interpreted by Harder et al (Geophys. Res. Lett., 36, L07801, doi:10.1029/2008GL036797, 2009) as implying a different spectral irradiance variation over the solar cycle than that put forward by Lean (Geophys. Res. Lett., 27, 2425-2428, 2000). When we inserted this new wavelength dependent solar cycle variation into our 3D CCM we found a different solar cycle dependence of the ozone concentration as a function of altitude from that we derived using the traditional Lean wavelength dependence. Examination of these results led us to realize that the main issue is the solar cycle variation of radiation at wavelengths less than 240 nm versus the solar cycle variation of radiation at wavelengths between 240 nm and 300 nm. The impact of wavelengths less than 240 nm occurs through photodissociation of O2 leading to the production of ozone. The impact of wavelengths between 240 nm and 300 nm occurs through photodissociation of O3 leading to an increase in O atoms and enhanced ozone destruction. Thus one wavelength region gives an in-phase relationship of ozone with the solar cycle while the other wavelength region gives an out-of-phase relationship of ozone with the solar cycle. We have used the Goddard two-dimensional (2D) photochemistry transport model to examine this relationship in more detail. We calculate the altitude and latitude sensitivity of ozone to changes in the solar UV irradiance as a function of wavelength. These results can be used to construct the ozone response to arbitrary wavelength dependencies of solar UV variation.

  17. Characteristics of solar wind density depletions during solar cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Park, K.; Lee, J.; Oh, S.; Yi, Y.

    2014-12-01

    Solar wind density depletions are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. To better understand the cause of the density depletions, we investigate the solar wind parameters and interplanetary magnetic field (IMF) data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the Advanced Composition Explorer (ACE) and the WIND satellite. As a result, we found that the solar wind density has an anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. We thus argue that IMF strength is an important factor in understanding the nature of solar wind density depletion. Since IMF strength varies with solar cycle, we also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an attempt to find its connection to the sun.

  18. Cosmic Ray Helium Intensities over the Solar Cycle from ACE

    NASA Technical Reports Server (NTRS)

    DeNolfo, G. A.; Yanasak, N. E.; Binns, W. R.; Cohen, C. M. S.; Cummings, A. C.; Davis, A. J.; George, J. S.; Hink. P. L.; Israel, M. H.; Lave, K.; Leske, R. A.; Mewaldt, R. A.; Moskalenko, I. V.; Ogliore, R.; Stone, E. C.; Von Rosenvinge, T. T.; Wiedenback, M. E.

    2007-01-01

    Observations of cosmic-ray helium energy spectra provide important constraints on cosmic ray origin and propagation. However, helium intensities measured at Earth are affected by solar modulation, especially below several GeV/nucleon. Observations of helium intensities over a solar cycle are important for understanding how solar modulation affects galactic cosmic ray intensities and for separating the contributions of anomalous and galactic cosmic rays. The Cosmic Ray Isotope Spectrometer (CRIS) on ACE has been measuring cosmic ray isotopes, including helium, since 1997 with high statistical precision. We present helium elemental intensities between approx. 10 to approx. 100 MeV/nucleon from the Solar Isotope Spectrometer (SIS) and CRIS observations over a solar cycle and compare these results with the observations from other satellite and balloon-borne instruments, and with GCR transport and solar modulation models.

  19. Evidence for Luni - Solar mn and Solar Cycle sc Signals in Australian Rainfall Data

    NASA Astrophysics Data System (ADS)

    Currie, Robert G.; Vines, Robert G.

    1996-11-01

    Spectrum analysis of 308 yearly sampled Australian rainfall series yields evidence for two terms with periods 18.3 +/- 1.8 and 10.5 +/-0.7 years in 270 and 182 instances, respectively. The long-period term is statistically significant at a confidence level of 99.9 per cent. They are identified as the 18.6-year luni-solar Mn and 10-11-year solar cycle Sc signals previously reported in other climate data such as American and South African rainfall, tree-rings world-wide, rainfall indices, air temperature world-wide, air pressure world-wide, sea-level world-wide, river flow, American crop yields and livestock/poultry production, European fish catches and dates of wine harvest, varves, thunderstorm occurrence, Earth rotation, and volcanic eruptions. In eastern Australia, Mn wave minima were in phase with epochs 1880.3 and 1898.9 (epochs are dates of maxima in tidal forcing). At mid-epoch 1908.2, epoch 1917.5, and mid-epoch 1926.8 virtually all luni-solar wavetrains experienced a 180° change in phase. Thus, by 1936.1 virtually all the waves were out of phase with the epoch, a correlation that continued at epochs 1954.7 and 1973.3. An entirely analogous phenomenon occurred in USA rainfall data, but it occurred in the third quarter of our century. The contribution of the Mn and Sc signals to total variance in the raw data is on average 19 per cent. This is of course highly unrealistic - and when the power in the raw data from 8 to 2 years is filtered out prior to analysis, and the variance contribution of the signals to filtered data compared over a common frequency interval (periods 30 to 8 years), their variance contribution increases dramatically to a mean of 89 per cent. Currie carried out similar analyses for six sets of climate data comprising over 3200 records and found the mean variance contribution of signals to filtered data over a common bandwidth varied from 67 to 81 per cent. Thus, the spectrum of climate at decadal and duo- decadal periods is strongly

  20. Forecast for solar cycle 23 activity: a progress report

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.

    2001-08-01

    At the 25th International Cosmic Ray Conference (ICRC) at Durban, South Africa, I announced the discovery of a three cycle quasi-periodicity in the ion chamber data string assembled by me, for the 1937 to 1994 period (Conf. Pap., v. 2, p. 109, 1997). It corresponded in time with a similar quasi-periodicity observed in the dataset for the planetary index Ap. At the 26th ICRC at Salt Lake City, UT, I reported on our analysis of the Ap data to forecast the amplitude of solar cycle 23 activity (Conf. Pap., v. 2, pl. 260, 1999). I predicted that cycle 23 will be moderate (a la cycle 17), notwithstanding the early exuberant forecasts of some solar astronomers that cycle 23, "may be one of the greatest cycles in recent times, if not the greatest." Sunspot number data up to April 2001 indicate that our forecast appears to be right on the mark. We review the solar, interplanetary and geophysical data and describe the important lessons learned from this experience. 1. Introduction Ohl (1971) was the first to realize that Sun may be sending us a subliminal message as to its intent for its activity (Sunspot Numbers, SSN) in the next cycle. He posited that the message was embedded in the geomagnetic activity (given by sum Kp). Schatten at al (1978) suggested that Ohl hypothesis could be understood on the basis of the model proposed by Babcock (1961) who suggested that the high latitude solar poloidal fields, near a minimum, emerge as the toroidal fields on opposite sides of the solar equator. This is known as the Solar Dynamo Model. One can speculate that the precursor poloidal solar field is entrained in the high speed solar wind streams (HSSWS) from the coronal holes which are observed at Earth's orbit during the descending phase of the previous cycle. The interaction

  1. Encore of the Bashful ballerina in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Virtanen, I. I.

    2009-04-01

    The rotation averaged location of the heliospheric current sheet has been found to be shifted systematically southward for about three years in the late declining to minimum phase of the solar cycle. This behaviour, called by the concept of the Bashful ballerina, has earlier been shown to be valid at least during the active solar cycle of the last century since the late 1920s. Recently, Zhao et al have analysed the WSO observations and conclude that there is no southward coning in HCS or north-south difference in the heliospheric magnetic field during the late declining phase of solar cycle 23. In disagreement with these results, we find that there is a similar but smaller southward shift of the HCS and dominance of the northern field area as in all previous solar cycles. The present smaller asymmetry is in agreement with an earlier observation based on long-term geomagnetic activity that solar hemispheric asymmetry is larger during highly active solar cycles. Moreover, we connect the smallness of shift to the structure of the solar magnetic field with an exceptionally large tilt. We also discuss the cause of the differences between the two approaches reaching different conclusions.

  2. Forecasting decadal and shorter time-scale solar cycle features

    NASA Astrophysics Data System (ADS)

    Dikpati, Mausumi

    2016-07-01

    Solar energetic particles and magnetic fields reach the Earth through the interplanetary medium and affect it in various ways, producing beautiful aurorae, but also electrical blackouts and damage to our technology-dependent economy. The root of energetic solar outputs is the solar activity cycle, which is most likely caused by dynamo processes inside the Sun. It is a formidable task to accurately predict the amplitude, onset and peak timings of a solar cycle. After reviewing all solar cycle prediction methods, including empirical as well as physical model-based schemes, I will describe what we have learned from both validation and nonvalidation of cycle 24 forecasts, and how to refine the model-based schemes for upcoming cycle 25 forecasts. Recent observations indicate that within a solar cycle there are shorter time-scale 'space weather' features, such as bursts of various forms of activity with approximately one year periodicity. I will demonstrate how global tachocline dynamics could play a crucial role in producing such space weather. The National Center for Atmospheric Research is sponsored by the National Science Foundation.

  3. Influence of the solar cycle on the Polar-night Jet Oscillation in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Kuroda, Yuhji; Deushi, Makoto

    2016-10-01

    The Polar-night Jet Oscillation (PJO) is the dominant mode of stratospheric variability in the Southern Hemisphere and persists from midwinter to spring. The influence of the 11 year solar cycle on modulation of the PJO from late winter to spring is examined using observations and three 42 year simulations from a chemistry-climate model. The only variation applied to model boundary conditions was the strength of ultraviolet (UV) radiation. This is set at 2 times larger than observations to enhance the strength of the solar signal. Simulations show a downward propagation of the stratospheric signal into the troposphere from late winter to spring, which tends to be enhanced as UV strength increases. This result is similar to observations but with a 1-2 month lag. The behavior of the PJO with respect to wave-mean flow interactions is examined using a newly developed momentum budget analysis as well as wave energy analysis. We suggest that UV modulation of the interactions between planetary waves and zonal-mean flow in the stratosphere, rather than direct diabatic processes as suggested in a previous study, is the source of solar cycle modulation of the PJO.

  4. Deep-space radiation exposure analysis for solar cycle XXI (1975-1986)

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Simonsen, Lisa C.; Townsend, Lawrence W.; Wilson, John W.

    1990-01-01

    Ionizing radiation exposures and associated dosimetric quantities are evaluated for the 11-year solar cycle ending in 1986. Solar flare fluences for the 55 largest flares occurring during the cycle are superimposed on the Galactic cosmic ray flux. Published summaries of flare data from the Interplanetary Monitoring Platform (IMP)-7 and IMP-8 satellites are used that include flares whose integrated fluences are greater than 10 to the 7th protons/sq cm for energies in excess of 10 MeV. A standard cosmic ray environment model for ion flux values at solar minimum and maximum is invoked with an assumed sinusoidal variation between the lower and upper limits. The radiation shielding analysis is carried out for equivalent water-shield thicknesses between 2 and 15 g/sq cm. Results are expressed in terms of cumulative incurred dose equivalents for deep-space missions lasting between 3 months and 3 years. It was found that medium-to-large flare contributions are of greatest importance for the shorter term missions, while the Galactic component dominates for the longer duration missions.

  5. Development of solar activity in 24th cycle: scenario of 15th cycle?

    NASA Astrophysics Data System (ADS)

    Lozytsky, V.; Efimenko, V.

    2012-12-01

    For more precise definition of prognosis of 24th cycle, the peculiarities of growth of solar activity was studied in previous 23 cycles. The interest was focused on a phase of sharp increasing of activity, beginning from 20th month of cycles. The sufficiently close correlation was found between smoothed Wolf's number in the cycle maximum Wmax and increment of sunspot's number on phase of activity increasing. From this analysis follows that for 24th cycle the following parameters are expected: Wmax = 105±11, аnd time of maximum - middle 2013. If this prognosis will be come true, the 24th cycle will be similar to cycle No. 15.

  6. Trends and solar cycle effects in mesospheric ice clouds

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Berger, Uwe; Fiedler, Jens; Baumgarten, Gerd; Gerding, Michael

    Lidar observations of mesospheric ice layers (noctilucent clouds, NLC) are now available since 12 years which allows to study solar cycle effects on NLC parameters such as altitudes, bright-ness, and occurrence rates. We present observations from our lidar stations in Kuehlungsborn (54N) and ALOMAR (69N). Different from general expectations the mean layer characteris-tics at ALOMAR do not show a persistent anti-correlation with solar cycle. Although a nice anti-correlation of Ly-alpha and occurrence rates is detected in the first half of the solar cycle, occurrence rates decreased with decreasing solar activity thereafter. Interestingly, in summer 2009 record high NLC parameters were detected as expected in solar minimum conditions. The morphology of NLC suggests that other processes except solar radiation may affect NLC. We have recently applied our LIMA model to study in detail the solar cycle effects on tempera-tures and water vapor concentration the middle atmosphere and its subsequent influence on mesospheric ice clouds. Furthermore, lower atmosphere effects are implicitly included because LIMA nudges to the conditions in the troposphere and lower stratosphere. We compare LIMA results regarding solar cycle effects on temperatures and ice layers with observations at ALO-MAR as well as satellite borne measurements. We will also present LIMA results regarding the latitude variation of solar cycle and trends, including a comparison of northern and southern hemisphere. We have adapted the observation conditions from SBUV (wavelength and scatter-ing angle) in LIMA for a detailed comparison with long term observations of ice clouds from satellites.

  7. An early solar dynamo prediction: Cycle 23 is approximately cycle 22

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Pesnell, W. Dean

    1993-01-01

    In this paper, we briefly review the 'dynamo' and 'geomagnetic precursor' methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the magnification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, through the development of the 'Solar Dynamo Amplitude' (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 210 +/- 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 170 +/- 25. This suggests that solar cycle #23 will be large, comparable to cycle #22. The estimated peak is expected to occur near 1999.7 +/- 1 year. Since the current approach is novel (using data prior to solar minimum), these estimates may improve when the upcoming solar minimum is reached.

  8. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  9. SOLAR CYCLE VARIATION OF THE INTER-NETWORK MAGNETIC FIELD

    SciTech Connect

    Jin, Chunlan; Wang, Jingxiu

    2015-06-20

    The solar inter-network magnetic field is the weakest component of solar magnetism, but it contributes most of the solar surface magnetic flux. The study of its origin has been constrained by the inadequate tempospatial resolution and sensitivity of polarization observations. With dramatic advances in spatial resolution and detecting sensitivity, the solar spectropolarimetry provided by the Solar Optical Telescope on board Hinode in an interval from the solar minimum to maximum of cycle 24 opens an unprecedented opportunity to study the cyclic behavior of the solar inter-network magnetic field. More than 1000 Hinode magnetograms observed from 2007 January to 2014 August are selected in the study. It has been found that there is a very slight correlation between sunspot number and magnetic field at the inter-network flux spectrum. From solar minimum to maximum of cycle 24, the flux density of the solar inter-network field is invariant, at 10 ± 1 G. The observations suggest that the inter-network magnetic field does not arise from flux diffusion or flux recycling of solar active regions, thereby indicating the existence of a local small-scale dynamo. Combining the full-disk magnetograms observed by the Solar and Heliospheric Observatory/Michelson Doppler Imager and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager in the same period, we find that the area ratio of the inter-network region to the full disk of the Sun apparently decreases from solar minimum to maximum but always exceeds 60%, even in the phase of solar maximum.

  10. Solar Cycle: Magnetized March to Equator

    NASA Video Gallery

    Bands of magnetized solar material – with alternating south and north polarity – march toward the sun's equator. Comparing the evolution of the bands with the sunspot number in each hemisphere over...

  11. Variation of solar acoustic emission and its relation to phase of the solar cycle

    NASA Astrophysics Data System (ADS)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

    Solar acoustic emission is closely related to solar convection and photospheric magnetic field. Variation of acoustic emission and its relation to the phase of solar cycles are important to understand dynamics of solar cycles and excitation of acoustic waves. In this work we use 6 years of SDO/HMI Dopplergram data to study acoustic emissions of the whole sun and of the quiet-sun regions, respectively, in multiple acoustic frequency bands. We show the variation of acoustic emission from May 2010 to April 2016, covering half of the solar cycle 24, and analyze its correlation with the solar activity level indexed by daily sunspot number and total magnetic flux. Results show that the correlation between the whole-Sun acoustic emission and the solar activity level is strongly negative for low frequencies between 2.5 and 4.5 mHz, but strongly positive for high frequencies between 4.5 and 6.0 mHz. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the acoustic emission in quiet regions and the solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz. This shows that the solar background acoustic power, with active regions excluded, also varies during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  12. Modeling and optimization of a hybrid solar combined cycle (HYCS)

    NASA Astrophysics Data System (ADS)

    Eter, Ahmad Adel

    2011-12-01

    The main objective of this thesis is to investigate the feasibility of integrating concentrated solar power (CSP) technology with the conventional combined cycle technology for electric generation in Saudi Arabia. The generated electricity can be used locally to meet the annual increasing demand. Specifically, it can be utilized to meet the demand during the hours 10 am-3 pm and prevent blackout hours, of some industrial sectors. The proposed CSP design gives flexibility in the operation system. Since, it works as a conventional combined cycle during night time and it switches to work as a hybrid solar combined cycle during day time. The first objective of the thesis is to develop a thermo-economical mathematical model that can simulate the performance of a hybrid solar-fossil fuel combined cycle. The second objective is to develop a computer simulation code that can solve the thermo-economical mathematical model using available software such as E.E.S. The developed simulation code is used to analyze the thermo-economic performance of different configurations of integrating the CSP with the conventional fossil fuel combined cycle to achieve the optimal integration configuration. This optimal integration configuration has been investigated further to achieve the optimal design of the solar field that gives the optimal solar share. Thermo-economical performance metrics which are available in the literature have been used in the present work to assess the thermo-economic performance of the investigated configurations. The economical and environmental impact of integration CSP with the conventional fossil fuel combined cycle are estimated and discussed. Finally, the optimal integration configuration is found to be solarization steam side in conventional combined cycle with solar multiple 0.38 which needs 29 hectare and LEC of HYCS is 63.17 $/MWh under Dhahran weather conditions.

  13. Discrepancy in behavior of different solar proxies in cycle 23

    NASA Astrophysics Data System (ADS)

    Lukianova, R.

    2009-04-01

    The Sun can influence the Earth climate through mechanisms that are not fully understood but which can be linked to solar variations of luminosity, magnetic field, UV radiation, solar flares and modulation of the cosmic ray intensity. Several proxies are used to characterize the Sun behavior and its influence on the geospheres. Solar activity over long time scales has usually been studied with the use of sunspot numbers (SN). The integrated radio flux from the solar disc (F10.7 index) follows the SN. Regular direct monitoring of solar irradiance has been made by satellites since 1978, resulting in time series of total solar irradiance (TSI) and variations of solar EUV irradiance (MgII index). The long-term components of all four solar proxies are expected to correlate linearly with each other. The situation was stable until the last solar maximum. Actually, cycle 23 had two maxima: one near middle of 2000 and another near end of 2001. According to SN, the magnitude of the first maximum was larger, whereas according to irradiance proxies, TSI and MgII, the second maximum was significantly higher. After this episode of enhanced irradiance (and until now) the mutual correspondence between published solar indices has been changed resulting in significant divergence. The present paper is aimed to the evaluation of discrepancy observed in different solar proxies. We examine the solar activity, namely the SN, F10.7, TSIs and MgII time series, in order to emphasis its unusual mutual behavior during the declining phase of cycle 23. Behavior of the solar indices is compared with the global ionospheric response using the F2 layer critical frequency from many observatories spread over the globe.

  14. Solar cycle variations in the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Smith, E. J.

    1983-01-01

    ISEE 3 interplanetary magnetic field measurements have been used to extend the NSSDC hourly averaged IMF composite data set through mid-1982. Most of sunspot cycle 20 (start:1964) and the first half of cycle 21 (start:1976) are now covered. The average magnitude of the field was relatively constant over cycle 20 with approx. 5-10% decreases in 1969 and 1971, when the Sun's polar regions changed polarity, and a 20% decrease in 1975-6 around solar minimum. Since the start of the new cycle, the total field strength has risen with the mean for the first third of 1982 being about 40% greater than the cycle 20 average. As during the previous cycle, an approx. 10% drop in IMF magnitude accompanied the 1980 reversal of the solar magnetic field. While the interplanetary magnetic field is clearly stronger during the present solar cycle, another 5-7 years of observations will be needed to determine if cycle 21 exhibits the same modest variations as the last cycle. Accordingly, it appears at this time that intercycle changes in IMF magnitude may be much larger than the intracycle variations.

  15. WHAT CAUSES THE INTER-SOLAR-CYCLE VARIATION OF TOTAL SOLAR IRRADIANCE?

    SciTech Connect

    Xiang, N. B.; Kong, D. F.

    2015-12-15

    The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statistical significance test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.

  16. What Causes the Inter-solar-cycle Variation of Total Solar Irradiance?

    NASA Astrophysics Data System (ADS)

    Xiang, N. B.; Kong, D. F.

    2015-12-01

    The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statistical significance test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.

  17. Comparative Analysis of the Activity Cycles of the Atmospheres of the Sun and of Stars of the Solar-Type

    NASA Astrophysics Data System (ADS)

    Bruevich, E. A.; Bruevich, V. V.; Shimanovskaya, E. V.

    2016-03-01

    The atmospheric activity of the sun and of stars of the solar-type is analyzed using observations from the HK-project at the Mount Wilson Observatory, California, and the Carnegie Planet Search Program at the Keck and Lick Observatories, as well as from the Magellan Planet Search Program at the Las Campanas Observatory. It is shown that a cyclical activity of the stars that is analogous to the 11-year solar activity cycle occurs in stars of spectral classes F, G, and K and is more pronounced in stars of class K. A comparative analysis of the solar-type stars with different levels of chromospheric and coronal activity confirms that the sun is one of the stars with a comparatively low level of atmospheric activity and that these stars have a minimal level of coronal emission and minimal variations in the fluxes of photospheric radiation.

  18. ENIGMA OF THE SOLAR CYCLE 4 STILL NOT RESOLVED

    SciTech Connect

    Zolotova, N. V.; Ponyavin, D. I.

    2011-08-01

    In this paper, the problem of the unusually long 4th sunspot cycle is discussed: was the length of this cycle exceptionally large or really composed of two short cycles? Analyzing the latitude-time diagram in 1784-1798, reconstructed from the drawings by Staudacher, Hamilton, and Gimingham, we suggest that the 4th cycle length can be a result of an impulse of activity in the northern hemisphere during the descending phase. The local minimum in 1793 can be just a gap between impulses of the solar activity, similar to the declining phase in the southern hemisphere of the long cycle 20. The long declining phase of cycle 4 is that the minimum in 1793 may also be due to lack of data. We have shown that sparse observations of the sunspots, in the second half of cycle 4, do not prove the existence of the 'lost' tiny cycle from 1793 to 1800.

  19. Prediction of solar activity from solar background magnetic field variations in cycles 21-23

    SciTech Connect

    Shepherd, Simon J.; Zharkov, Sergei I.; Zharkova, Valentina V. E-mail: s.zharkov@hull.ac.uk

    2014-11-01

    A comprehensive spectral analysis of both the solar background magnetic field (SBMF) in cycles 21-23 and the sunspot magnetic field in cycle 23 reported in our recent paper showed the presence of two principal components (PCs) of SBMF having opposite polarity, e.g., originating in the northern and southern hemispheres, respectively. Over a duration of one solar cycle, both waves are found to travel with an increasing phase shift toward the northern hemisphere in odd cycles 21 and 23 and to the southern hemisphere in even cycle 22. These waves were linked to solar dynamo waves assumed to form in different layers of the solar interior. In this paper, for the first time, the PCs of SBMF in cycles 21-23 are analyzed with the symbolic regression technique using Hamiltonian principles, allowing us to uncover the underlying mathematical laws governing these complex waves in the SBMF presented by PCs and to extrapolate these PCs to cycles 24-26. The PCs predicted for cycle 24 very closely fit (with an accuracy better than 98%) the PCs derived from the SBMF observations in this cycle. This approach also predicts a strong reduction of the SBMF in cycles 25 and 26 and, thus, a reduction of the resulting solar activity. This decrease is accompanied by an increasing phase shift between the two predicted PCs (magnetic waves) in cycle 25 leading to their full separation into the opposite hemispheres in cycle 26. The variations of the modulus summary of the two PCs in SBMF reveals a remarkable resemblance to the average number of sunspots in cycles 21-24 and to predictions of reduced sunspot numbers compared to cycle 24: 80% in cycle 25 and 40% in cycle 26.

  20. Solar cycle variation of thermospheric nitric oxide at solstice

    NASA Technical Reports Server (NTRS)

    Gerard, J.-C.; Fesen, C. G.; Rusch, D. W.

    1990-01-01

    A coupled, two-dimensional, chemical-diffusive model of the thermosphere is used to study the role of solar activity in the global distribution of nitric oxide. The model calculates self-consistently the zonally averaged temperature, circulation, and composition for solstice under solar maximum and solar minimum conditions. A decrease of the NO density by a factor of three to four in the E region is predicted from solar maximum to solar minimum. It is found that the main features of the overall morphology and the changes induced by the solar cycle are well reproduced in the model, although some details are not satisfactorily predicted. The sensitivity of the NO distribution to eddy transport and to the quenching of metastable N(2D) atoms by atomic oxygen is also described.

  1. The quasi-biennial periodicity (QBP) in velocity and intensity helioseismic observations. The seismic QBP over solar cycle 23

    NASA Astrophysics Data System (ADS)

    Simoniello, R.; Finsterle, W.; Salabert, D.; García, R. A.; Turck-Chièze, S.; Jiménez, A.; Roth, M.

    2012-03-01

    Aims: We looked for signatures of quasi-biennial periodicity (QBP) over different phases of solar cycle by means of acoustic modes of oscillation. Low-degree p-mode frequencies are shown to be sensitive to changes in magnetic activity due to the global dynamo. Recently there has been reported evidence of two-year variations in p-mode frequencies. Methods: Long high-quality helioseismic data are provided by BiSON (Birmingham Solar Oscillation Network), GONG (Global Oscillation Network Group), GOLF (Global Oscillation at Low Frequency) and VIRGO (Variability of Solar IRradiance and Gravity Oscillation) instruments. We determined the solar cycle changes in p-mode frequencies for spherical degree ℓ = 0, 1, 2 with their azimuthal components in the frequency range 2.5 mHz ≤ ν ≤ 3.5 mHz. Results: We found signatures of QBP at all levels of solar activity in the modes more sensitive to higher latitudes. The signal strength increases with latitude and the equatorial component also seems to be modulated by the 11-year envelope. Conclusions: The persistent nature of the seismic QBP is not observed in the surface activity indices, where mid-term variations are found only from time to time and mainly in periods of high activity. This feature, together with the latitudinal dependence, provides more evidence of a mechanism that is almost independent and different from the one that brings the active regions up to the surface. Therefore, these findings can be used to provide more constraints on dynamo models that consider a further cyclic component on top of the 11-year cycle.

  2. Hubble Space Telescope solar cell module thermal cycle test

    NASA Technical Reports Server (NTRS)

    Douglas, Alexander; Edge, Ted; Willowby, Douglas; Gerlach, Lothar

    1992-01-01

    The Hubble Space Telescope (HST) solar array consists of two identical double roll-out wings designed after the Hughes flexible roll-up solar array (FRUSA) and was developed by the European Space Agency (ESA) to meet specified HST power output requirements at the end of 2 years, with a functional lifetime of 5 years. The requirement that the HST solar array remain functional both mechanically and electrically during its 5-year lifetime meant that the array must withstand 30,000 low Earth orbit (LEO) thermal cycles between approximately +100 and -100 C. In order to evaluate the ability of the array to meet this requirement, an accelerated thermal cycle test in vacuum was conducted at NASA's Marshall Space Flight Center (MSFC), using two 128-cell solar array modules which duplicated the flight HST solar array. Several other tests were performed on the modules. The thermal cycle test was interrupted after 2,577 cycles, and a 'cold-roll' test was performed on one of the modules in order to evaluate the ability of the flight array to survive an emergency deployment during the dark (cold) portion of an orbit. A posttest static shadow test was performed on one of the modules in order to analyze temperature gradients across the module. Finally, current in-flight electrical performance data from the actual HST flight solar array will be tested.

  3. Solar cycle signal in air temperature in North America - Amplitude, gradient, phase and distribution

    NASA Technical Reports Server (NTRS)

    Currie, R. G.

    1981-01-01

    The considered investigation was motivated by three factors. One is related to an extension of single-channel MESA to multi-channel by Strand (1977), Morf et al. (1978), and Jones (1978). MESA is a high-resolution signal processing and spectrum analysis technique due to Burg (1975). The considered developments resulted in the discovery of the 11-year solar cycle signal in the change of the length of day by Currie (1980, 1981). They also led Currie (1981) to study the phase spectrum of the 11-year term in height H of sea level. The investigation tries to clarify the phase relations among the involved parameters. The second factor is connected with an application of the linear time domain technique used by Currie (1981) to temperature records to obtain more accurate information regarding the signal amplitude. The third factor of motivation is related to increases in the number of stations available for an analysis, the greater average length of the records, and the more accurate data set.

  4. Evolution of solar wind turbulence and intermittency over the solar cycle

    NASA Astrophysics Data System (ADS)

    Väisänen, Pauli; Virtanen, Ilpo; Echim, Marius; Munteanu, Costel; Mursula, Kalevi

    2016-04-01

    Solar wind is a natural, near-by plasma physics laboratory, which offers possibilities to study plasma physical phenomena over a wide range of parameter values that are difficult to reach in ground-based laboratories. Accordingly, the solar wind is subject of many studies of, e.g., intermittency, turbulence and other nonlinear space plasma phenomena. Turbulence is an important feature of the solar wind dynamics, e.g., for the energy transfer mechanisms and their scale invariance, the solar wind evolution, the structure of the heliospheric magnetic field (HMF), the particle energization and heating, and for phenomena related to solar wind interaction with the planetary plasma systems. Here we analyse high resolution measurements of the solar wind and the heliospheric magnetic field provided by several ESA and NASA satellites, including ACE, STEREO, Ulysses and Cluster. This collection of satellites allows us to compile and study nearly 20 years of high-resolution solar wind and HMF measurements from the start of solar cycle 23 to the current declining phase of solar cycle 24. Long-term studies require homogeneity and, therefore, we pay great attention to the reliability and consistency of the data, in particular to instrumental defects like spin harmonics, the purity of the solar wind and its possible contamination in the foreshock by magnetospheric ions. We study how the different key-descriptors of turbulence like the slope of the power law of power spectral density and the kurtosis of the fluctuations of the heliospheric magnetic field vary over the solar cycle.

  5. Connection between solar activity cycles and grand minima generation

    NASA Astrophysics Data System (ADS)

    Vecchio, A.; Lepreti, F.; Laurenza, M.; Alberti, T.; Carbone, V.

    2017-03-01

    Aims: The revised dataset of sunspot and group numbers (released by WDC-SILSO) and the sunspot number reconstruction based on dendrochronologically dated radiocarbon concentrations have been analyzed to provide a deeper characterization of the solar activity main periodicities and to investigate the role of the Gleissberg and Suess cycles in the grand minima occurrence. Methods: Empirical mode decomposition (EMD) has been used to isolate the time behavior of the different solar activity periodicities. A general consistency among the results from all the analyzed datasets verifies the reliability of the EMD approach. Results: The analysis on the revised sunspot data indicates that the highest energy content is associated with the Schwabe cycle. In correspondence with the grand minima (Maunder and Dalton), the frequency of this cycle changes to longer timescales of 14 yr. The Gleissberg and Suess cycles, with timescales of 60-120 yr and 200-300 yr, respectively, represent the most energetic contribution to sunspot number reconstruction records and are both found to be characterized by multiple scales of oscillation. The grand minima generation and the origin of the two expected distinct types of grand minima, Maunder and longer Spörer-like, are naturally explained through the EMD approach. We found that the grand minima sequence is produced by the coupling between Gleissberg and Suess cycles, the latter being responsible for the most intense and longest Spörer-like minima (with typical duration longer than 80 yr). Finally, we identified a non-solar component, characterized by a very long scale oscillation of 7000 yr, and the Hallstatt cycle ( 2000 yr), likely due to the solar activity. Conclusions: These results provide new observational constraints on the properties of the solar cycle periodicities, the grand minima generation, and thus the long-term behavior of the solar dynamo.

  6. Analysis of variability of p-mode parameters in 11 years of IRIS data

    NASA Astrophysics Data System (ADS)

    Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Cacciani, A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Lazrek, M.; Pallé, P.; Schmider, F. X.; Tomczyk, S.

    2002-03-01

    11 years of IRIS (the low degree helioseismology network) have been analysed for the study of p-modes parameters variability. The duty cycle of the network data has been improved by the partial gap filling method named "repetitive music". This paper discusses the variations of all p-modes parameters along these 11 years.

  7. Interannual Variations of MLS Carbon Monoxide Induced by Solar Cycle

    NASA Technical Reports Server (NTRS)

    Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander

    2013-01-01

    More than eight years (2004-2012) of carbon monoxide (CO) measurements from the Aura Microwave Limb Sounder (MLS) are analyzed. The mesospheric CO, largely produced by the carbon dioxide (CO2) photolysis in the lower thermosphere, is sensitive to the solar irradiance variability. The long-term variation of observed mesospheric MLS CO concentrations at high latitudes is likely driven by the solar-cycle modulated UV forcing. Despite of different CO abundances in the southern and northern hemispheric winter, the solar-cycle dependence appears to be similar. This solar signal is further carried down to the lower altitudes by the dynamical descent in the winter polar vortex. Aura MLS CO is compared with the Solar Radiation and Climate Experiment (SORCE) total solar irradiance (TSI) and also with the spectral irradiance in the far ultraviolet (FUV) region from the SORCE Solar-Stellar Irradiance Comparison Experiment (SOLSTICE). Significant positive correlation (up to 0.6) is found between CO and FUVTSI in a large part of the upper atmosphere. The distribution of this positive correlation in the mesosphere is consistent with the expectation of CO changes induced by the solar irradiance variations.

  8. Statistical pecularities of 24th cycle of solar activity

    NASA Astrophysics Data System (ADS)

    Efimenko, V.; Lozitsky, V.

    2016-06-01

    Current 24th cycle of solar activity is anomalous if following aspects: 1) it had non-monotonous phase of grown, and on different times of this phase it demonstrated peculiarities of both middle and weak cycle, 2) peak of cycle was two-top, and second top was higher than first on about 15 units of averages Wolf's number (in old classification) that is maximum value for all previous cycles, and 3) temporal interval between first and second maximums of cycle was 26 months that is second value from all 24 cycles. As to index of integral distribution of sunspot diameters, it was found earlier that this index α, in the average, equals about 6.0 for 7 previous cycles, in diameter range 50–90 Mm. New statistical analysis based on data for 2010–2015 allows to conclude that for 24th cycle α ≈ 5.8. Thus, dispersion of diameters of sunspots in 24th cycle is typical for majority of solar cycles.

  9. Background magnetic fields during last three cycles of solar activity

    NASA Astrophysics Data System (ADS)

    Andryeyeva, O. A.; Stepanian, N. N.

    2008-07-01

    This paper describes our studies of evolution of the solar magnetic field with different sign and field strength in the range from -100 G to 100 G. The structure and evolution of large-scale magnetic fields on the Sun during the last 3 cycles of solar activity is investigated using magnetograph data from the Kitt Peak Solar Observatory. This analysis reveals two groups of the large-scale magnetic fields evolving differently during the cycles. The first group is represented by relatively weak background fields, and is best observed in the range of 3-10 Gauss. The second group is represented by stronger fields of 75-100 Gauss. The spatial and temporal properties of these groups are described and compared with the total magnetic flux. It is shown that the anomalous behaviour of the total flux during the last cycle can be found only in the second group

  10. A double magnetic solar cycle and dynamical systems

    NASA Astrophysics Data System (ADS)

    Popova, H.

    Various solar activity data have indicated that along with the well-known 22-year cycle there is a shorter periodicity of about 2 years. To simulate this phenomenon, we constructed a dynamical system, which reproduced double-periodic behaviour of the solar cycle. Such nonlinear dynamical system described the solar αω-dynamo process with variable intensities Rα and Rω of the α-effect and the differential rotation, respectively. We have plotted the time distribution and butterfly diagrams for the poloidal and toroidal magnetic fields with dipole and quadrupole symmetries. The dynamical system with dipole symmetry of the magnetic field reproduces a regime similar to the double cycle at -450 < RαRω < -210. In the case of quadrupole symmetry, this regime exists at -220 < RαRω < -190.

  11. CORONAL MASS EJECTIONS AND THE SOLAR CYCLE VARIATION OF THE SUN’S OPEN FLUX

    SciTech Connect

    Wang, Y.-M.; Sheeley, N. R. Jr. E-mail: neil.sheeley@nrl.navy.mil

    2015-08-20

    The strength of the radial component of the interplanetary magnetic field (IMF), which is a measure of the Sun’s total open flux, is observed to vary by roughly a factor of two over the 11 year solar cycle. Several recent studies have proposed that the Sun’s open flux consists of a constant or “floor” component that dominates at sunspot minimum, and a time-varying component due to coronal mass ejections (CMEs). Here, we point out that CMEs cannot account for the large peaks in the IMF strength which occurred in 2003 and late 2014, and which coincided with peaks in the Sun’s equatorial dipole moment. We also show that near-Earth interplanetary CMEs, as identified in the catalog of Richardson and Cane, contribute at most ∼30% of the average radial IMF strength even during sunspot maximum. We conclude that the long-term variation of the radial IMF strength is determined mainly by the Sun’s total dipole moment, with the quadrupole moment and CMEs providing an additional boost near sunspot maximum. Most of the open flux is rooted in coronal holes, whose solar cycle evolution in turn reflects that of the Sun’s lowest-order multipoles.

  12. Solar neutron decay proton observations in cycle 21

    NASA Technical Reports Server (NTRS)

    Evenson, Paul; Kroeger, Richard; Meyer, Peter; Reames, Donald

    1990-01-01

    Measurement of the flux and energy spectrum of the protons resulting from the decay of solar flare neutrons gives unique information on the spectrum of neutrons from 5 to 200 MeV. Neutrons from three flares have been observed in this manner during solar cycle 21. The use of the decay protons to determine neutron energy spectra is reviewed, and new and definitive energy spectra are presented for the two large flares on June 3, 1982 and April 25, 1984.

  13. Investigation of X-ray and optical solar flare activities during solar cycles 22 and 23

    NASA Astrophysics Data System (ADS)

    Akimov, L. A.; Belkina, I. L.; Bushueva, T. P.

    2003-02-01

    Daily X-ray flare indices (XFI) for the interval from January 1986 till June 2002 were calculated. The XFI behaviour during solar cycles 22 and 23 was studied. We compare the daily XFI with the daily optical flare indices (OFI) and with the International Relative Sunspot Numbers. The energy emitted by X-ray flares during 77 months of solar cycle 22 is shown to be about five times larger than the analogous value for the present solar cycle. We revealed statistically significant maxima in power spectra of the XFI and OFI. They correspond to periods of 25.5, 36.5, 73, 116, and 150d which presumably are appropriate to characteristic frequencies of the solar flare activity. A hypothesis on an possible effect of Mercury's variable electric charge on the origin of solar flares is proposed and corresponding estimates were made.

  14. SOLAR ROTATION RATE DURING THE CYCLE 24 MINIMUM IN ACTIVITY

    SciTech Connect

    Antia, H. M.; Basu, Sarbani E-mail: sarbani.basu@yale.ed

    2010-09-01

    The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to now, we study the differences in the nature of the solar rotation between the minima of cycles 23 and 24. We find that there are significant differences between the rotation rates during the two minima. There are differences in the zonal-flow pattern too. We find that the band of fast rotating region close to the equator bifurcated around 2005 and recombined by 2008. This behavior is different from that during the cycle 23 minimum. By autocorrelating the zonal-flow pattern with a time shift, we find that in terms of solar dynamics, solar cycle 23 lasted for a period of 11.7 years, consistent with the result of Howe et al. (2009). The autocorrelation coefficient also confirms that the zonal-flow pattern penetrates through the convection zone.

  15. Modeling the heliospheric current sheet: Solar cycle variations

    NASA Astrophysics Data System (ADS)

    Riley, Pete; Linker, J. A.; Mikić, Z.

    2002-07-01

    In this report we employ an empirically driven, three-dimensional MHD model to explore the evolution of the heliospheric current sheet (HCS) during the course of the solar cycle. We compare our results with a simpler ``constant-speed'' approach for mapping the HCS outward into the solar wind to demonstrate that dynamic effects can substantially deform the HCS in the inner heliosphere (<~5 AU). We find that these deformations are most pronounced at solar minimum and become less significant at solar maximum, when interaction regions are less effective. Although solar maximum is typically associated with transient, rather than corotating, processes, we show that even under such conditions, the HCS can maintain its structure over the course of several solar rotations. While the HCS may almost always be topologically equivalent to a ``ballerina skirt,'' we discuss an interval approaching the maximum of solar cycle 23 (Carrington rotations 1960 and 1961) when the shape would be better described as ``conch shell''-like. We use Ulysses magnetic field measurements to support the model results.

  16. A Different View of Solar Spectral Irradiance Variations: Modeling Total Energy of a Solar Outburst Period in 2005 and its Comparison to Solar Cycle 23 and 24 Measured Variability

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Snow, Martin; Harder, Jerald; Chapman, Gary; Cookson, Angela

    2015-08-01

    A different approach to studying solar spectral irradiance (SSI) variations, without the need for long-term (multi-year) instrument degradation corrections, is by examining the total energy of the irradiance variation during solar outburst periods. A solar active region typically appears suddenly and then takes about seven months to decay and disperse back into the quiet Sun network. An outburst period is defined as a time when one major active region dominates the irradiance variation. The solar outburst energy, which includes the energy from all phases of active region evolution, could be considered the primary cause for irradiance variations. Because solar cycle variation is the consequence of multiple active region outbursts, understanding the variation from a single active region outburst can provide a reasonable estimate of the variations for the 11-year solar activity cycle. The moderate-term (~6 months) variations from the Solar Radiation and Climate Experiment (SORCE) instruments during a solar outburst period in early 2005 are decomposed into positive (in-phase with solar cycle) and negative (out-of-phase) contributions by modeling the variations using the San Fernando Observatory (SFO) facular excess and sunspot deficit proxies, respectively. These fitted excess and deficit variations are then integrated over time for the energy during this outburst period, and the dominant component indicates which wavelengths are in-phase and which are out-of-phase with solar activity. The results from this study indicate out-of-phase variations for the 1210-1600 nm range, with all other wavelengths having in-phase variations.

  17. BLOOD PRESSURE, HEART RATE AND MELATONIN CYCLES SYNCHRONIZATION WITH THE SEASON, EARTH MAGNETISM AND SOLAR FLARES.

    PubMed

    Cornélissen, G; Halberg, F; Sothern, R B; Hillman, D C; Siegelová, J

    2010-01-01

    other aspect of RBS' physical environment, namely the seasons (at ~1.0 year), earth magnetism (at ~0.5 year) and/or solar flares (at ~0.42 year). Cosmic-biotic transfer of information, albeit hardly of energy (the biospheric amplitudes are very small) may be mediated in this set of frequency windows. As found earlier, RBS' circulation is also frequency-trapped environmentally in multidecadal windows, HR being locked into the transtridecadal Brückner, or rather Brückner-Egeson-Lockyer, BEL sunspot and terrestrial weather cycle, while his BP follows Hale's didecadal cycle in the changing polarity of sunspots.The ~0.41-year HR cycle may be associated with changes in solar flares, the cis-half-year amplitude of HR showing a cross-correlation coefficient of 0.79 with the total solar flare index (from both solar hemispheres) at a lag of ~3.2 years. The superposed time courses of these two variables indicate the presence of a shared Horrebow-Arago-Schwabe sunspot cycle of ~11 years, the cis-half-year in HR being more prominent after the total solar flare index reaches its ~11-year peak. Differences in the time-varying behavior of BP vs. HR are also described.

  18. BATSE flare observations in Solar Cycle 22

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Dennis, B. R.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W. S.

    1992-01-01

    The Hard X-Ray Burst Spectrometer (HXRBS) group at GSFC has developed and is maintaining a quick-look analysis system for solar flare hard x-ray data from the Burst and Transient Source Experiment (BATSE) on the recently launched Compton Gamma-Ray Observatory (GRO). The instrument consists, in part, of 8 large planar detectors, each 2025 sq cm, placed on the corners of the GRO spacecraft with the orientation of the faces being those of a regular octahedron. Although optimized for the detection of gamma-ray bursts, these detectors are far more sensitive than any previous spacecraft-borne hard x-ray flare instrumentation both for the detection of small microflares and the resolution of fine temporal structures. The data in this BATSE solar data base are from the discriminator large area (DISCLA) rates. From each of eight detectors there are hard x-ray data in four energy channels, 25-50, 50-100, 100-300, and greater than 300 keV with a time resolution of 1.024 seconds. These data are suitable for temporal correlation with data at other wavelengths, and they provide a first look into the BATSE and other GRO instrument flare data sets. The BATSE and other GRO principle investigator groups should be contacted for the availability of data sets at higher time or spectral resolution or at higher energies.

  19. Solar and interplanetary signatures of declining of solar magnetic fields: Implications to the next solar cycle 25

    NASA Astrophysics Data System (ADS)

    Bisoi, Susanta Kumar; Janardhan, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.

    2015-08-01

    Our detailed study of solar surface magnetic fields at high-latitudes, using magnetic synoptic magnetograms of NSO/Kitt Peak observatory from 1975-2014, has shown a steady decline of the field strength since mid-1990's until mid-2014, i.e. the solar maximum of cycle 24. We also found that magnetic field strength at high-latitudes declines after each solar cycle maximum, and since cycle 24 is already past its peak implies that solar surface magnetic fields will be continuing to decline until solar minimum of cycle 24. In addition, interplanetary scintillation (IPS) measurements of solar wind micro-turbulence levels, from Solar and Terrestrial Environment Laboratory (STEL), Japan, have also shown a steady decline in sync with the declining surface fields. Even the heliospheric magnetic fields (HMF) at 1 AU have been declined much below the previously proposed floor level of HMF of ~4.6 nT. From study of a correlation between the high-latitude surface fields and the HMF at the last four solar minima we found a floor value of HMF of ~3.2 nT. Using the above correlation and the fact that the high-latitude surface fields is expected to decline until the minimum of cycle 24, we estimate the value of the HMF at the minimum of cycle 24 will be 3.8 ± 0.2 nT and the peak sunspot number for solar cycle 25 will be 56±12 suggesting a weak sunspot activity to be continued in cycle 25 too.

  20. Solar High Temperature Water-Splitting Cycle with Quantum Boost

    SciTech Connect

    Taylor, Robin; Davenport, Roger; Talbot, Jan; Herz, Richard; Genders, David; Symons, Peter; Brown, Lloyd

    2014-04-25

    A sulfur family chemical cycle having ammonia as the working fluid and reagent was developed as a cost-effective and efficient hydrogen production technology based on a solar thermochemical water-splitting cycle. The sulfur ammonia (SA) cycle is a renewable and sustainable process that is unique in that it is an all-fluid cycle (i.e., with no solids handling). It uses a moderate temperature solar plant with the solar receiver operating at 800°C. All electricity needed is generated internally from recovered heat. The plant would operate continuously with low cost storage and it is a good potential solar thermochemical hydrogen production cycle for reaching the DOE cost goals. Two approaches were considered for the hydrogen production step of the SA cycle: (1) photocatalytic, and (2) electrolytic oxidation of ammonium sulfite to ammonium sulfate in aqueous solutions. Also, two sub-cycles were evaluated for the oxygen evolution side of the SA cycle: (1) zinc sulfate/zinc oxide, and (2) potassium sulfate/potassium pyrosulfate. The laboratory testing and optimization of all the process steps for each version of the SA cycle were proven in the laboratory or have been fully demonstrated by others, but further optimization is still possible and needed. The solar configuration evolved to a 50 MW(thermal) central receiver system with a North heliostat field, a cavity receiver, and NaCl molten salt storage to allow continuous operation. The H2A economic model was used to optimize and trade-off SA cycle configurations. Parametric studies of chemical plant performance have indicated process efficiencies of ~20%. Although the current process efficiency is technically acceptable, an increased efficiency is needed if the DOE cost targets are to be reached. There are two interrelated areas in which there is the potential for significant efficiency improvements: electrolysis cell voltage and excessive water vaporization. Methods to significantly reduce water evaporation are

  1. Mir Cooperative Solar Array Project Accelerated Life Thermal Cycling Test

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Scheiman, David A.

    1996-01-01

    The Mir Cooperative Solar Array (MCSA) project was a joint U.S./Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA will be used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station. The MCSA was brought to Mir by space shuttle Atlantis in November 1995. This report describes an accelerated thermal life cycle test which was performed on two samples of the MCSA. In eight months time, two MCSA solar array 'mini' panel test articles were simultaneously put through 24,000 thermal cycles. There was no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early and removed from consideration. The nature of the performance degradation caused by this one cell is briefly discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the U.S. solar cell modules with the Russian support structure would be able to withstand at least 24,000 thermal cycles (4 years on-orbit). This was considered a successful development test.

  2. Correlation between solar acoustic emission and phase of the solar cycle

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, J.

    2015-12-01

    The solar acoustic emission is closely related to solar convection and magnetic field. Understanding the relation between the acoustic emission and the phase of a solar cycle is important to understand the dynamics of solar cycles and excitation of acoustic waves. In this work we use 4 years of SDO/HMI data from 05/2010 to 04/2014, covering the growing phase of the solar cycle 24, to study the acoustic emissions of the whole sun and of only the quiet sun regions respectively, at multiple frequency bands. We also analyze the correlations between the acoustic emissions and solar activity level indexed by daily sunspot number and magnetic flux. The results show that the correlation between the whole-sun acoustic emission and solar activity level is negative for low frequencies at 2.5-4.5 mHz, with a peak value around -0.9, and is positive for high frequencies at 4.5-6.0 mHz, with a peak value around 0.9. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the quiet-sun acoustic emission and solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz, with peak values over ±0.8. This shows that the solar background acoustic power, with active regions excluded, is indeed varying during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  3. OH Column Abundance Apparent Response to Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Burnett, C. R.; Minschwaner, K. R.

    2009-12-01

    The 33-year series of high spectral resolution measurements of absorption of sunlight by OH at 308 nm has exhibited temporary decreases of column abundances in 1986, 1997, and 2008 near the times of minimum solar activity. These observations and analyses are of significance as they encompass three complete solar cycles for comparison. During solar cycle 23, the annual average abundances increased approximately 20% from the minimum abundance in 1997 to high-sun enhanced values in 2000-2006, then dropped approximately 15% in 2008. The abundances exhibited a pronounced reduction at solar minimum in August-October 2008, similar to that seen in fall 1986 and fall 1997. The average morning abundances on those occasions were 13% smaller than the 1980-88 corresponding average, about 0.9 x 1013 cm-2, with minimum values broadly consistent with model results. In contrast, high-sun OH abundances observed during periods of solar maximum are approximately 33% larger than modeled abundances. This discrepancy cannot be explained by reasonable adjustments of reaction rates or modeled constituent concentrations in the stratosphere or mesosphere. However, the observed responses to a tropopause fold event in 1988 and to the Pinatubo aerosol in 1991 do suggest an important contribution to the total OH column from the lower stratosphere. In addition to the apparent variations with solar activity, this OH column database contains a number of other effects such as diurnal and seasonal patterns, and geographic differences between observations from Colorado, Florida, Alaska, Micronesia, New Zealand, and New Mexico.

  4. Variations in the Sun's Meridional Flow Over a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Rightmire, Lisa

    2010-01-01

    The Sun's meridional flow is an axisymmetric flow that is generally directed from its equator toward its poles at the surface. The structure and strength of the meridional flow determine both the strength of the Sun's polar magnetic field and the intensity of sunspot cycles. We determine the meridional flow speed of magnetic features on the Sun using data from the Solar and Heliospheric Observatory. The average flow is poleward at all latitudes up to 75 , which suggests that it extends to the poles. It was faster at sun spot cycle minimum than at maximum and substantially faster on the approach to the current minimum than it was at the last solar minimum. This result may help to ex plain why this solar activity minimum is so peculiar.

  5. Variations of solar, interplanetary, and geomagnetic parameters with solar magnetic multipole fields during Solar Cycles 21-24

    NASA Astrophysics Data System (ADS)

    Kim, Bogyeong; Lee, Jeongwoo; Yi, Yu; Oh, Suyeon

    2015-01-01

    In this study we compare the temporal variations of the solar, interplanetary, and geomagnetic (SIG) parameters with that of open solar magnetic flux from 1976 to 2012 (from Solar Cycle 21 to the early phase of Cycle 24) for a purpose of identifying their possible relationships. By the open flux, we mean the average magnetic field over the source surface (2.5 solar radii) times the source area as defined by the potential field source surface (PFSS) model of the Wilcox Solar Observatory (WSO). In our result, most SIG parameters except the solar wind dynamic pressure show rather poor correlations with the open solar magnetic field. Good correlations are recovered when the contributions from individual multipole components are counted separately. As expected, solar activity indices such as sunspot number, total solar irradiance, 10.7 cm radio flux, and solar flare occurrence are highly correlated with the flux of magnetic quadrupole component. The dynamic pressure of solar wind is strongly correlated with the dipole flux, which is in anti-phase with Solar Cycle (SC). The geomagnetic activity represented by the Ap index is correlated with higher order multipole components, which show relatively a slow time variation with SC. We also found that the unusually low geomagnetic activity during SC 23 is accompanied by the weak open solar fields compared with those in other SCs. It is argued that such dependences of the SIG parameters on the individual multipole components of the open solar magnetic flux may clarify why some SIG parameters vary in phase with SC and others show seemingly delayed responses to SC variation.

  6. Cycle Length Dependence of Stellar Magnetic Activity and Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Choi, Hwajin; Lee, Jeongwoo; Oh, Suyeon; Kim, Bogyeong; Kim, Hoonkyu; Yi, Yu

    2015-03-01

    Solar cycle (SC) 23 was extraordinarily long with remarkably low magnetic activity. We have investigated whether this is a common behavior of solar-type stars. From the Ca ii H and K line intensities of 111 stars observed at Mount Wilson Observatory from 1966 to 1991, we have retrieved data of all 23 G-type stars and recalculated their cycle lengths using the damped least-squares method for the chromospheric activity index S as a function of time. A regression analysis was performed to find relations between the derived cycle length, Pavg, and the index for excess chromospheric emission, RHK\\prime . As a noteworthy result, we found a segregation between young and old solar-type stars in the cycle length-activity correlation. We incorporated the relation for the solar-type stars into the previously known rule for stellar chromospheric activity and brightness to estimate the variation of solar brightness from SC 22 to SC 23 as (0.12 ± 0.06)%, much higher than the actual variation of total solar irradiance (TSI) ≤0.02%. We have then examined solar spectral irradiance (SSI) to find a good phase correlation with a sunspot number in the wavelength range of 170-260 nm, which is close to the spectral range effective in heating the Earth’s atmosphere. Therefore, it appears that SSI rather than TSI is a good indicator of the chromospheric activity, and its cycle length dependent variation would be more relevant to the possible role of the Sun in the cyclic variation of the Earth’s atmosphere.

  7. SOLAR MAGNETIC HELICITY INJECTED INTO THE HELIOSPHERE: MAGNITUDE, BALANCE, AND PERIODICITIES OVER SOLAR CYCLE 23

    SciTech Connect

    Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.; Pevtsov, A. A.; Kuzanyan, K. M.

    2009-11-01

    Relying purely on solar photospheric magnetic field measurements that cover most of solar cycle 23 (1996-2005), we calculate the total relative magnetic helicity injected into the solar atmosphere, and eventually shed into the heliosphere, over the latest cycle. Large active regions dominate the helicity injection process with approx5.7 x 10{sup 45} Mx{sup 2} of total injected helicity. The net helicity injected is approx<1% of the above output. Peculiar active-region plasma flows account for approx80% of this helicity; the remaining approx20% is due to solar differential rotation. The typical helicity per active-region CME ranges between (1.8-7) x 10{sup 42} Mx{sup 2} depending on the CME velocity. Accounting for various minor underestimation factors, we estimate a maximum helicity injection of approx6.6 x 10{sup 45} Mx{sup 2} for solar cycle 23. Although no significant net helicity exists over both solar hemispheres, we recover the well-known hemispheric helicity preference, which is significantly enhanced by the solar differential rotation. We also find that helicity injection in the solar atmosphere is an inherently disorganized, impulsive, and aperiodic process.

  8. No link between the solar activity cycle and the diameter

    NASA Astrophysics Data System (ADS)

    Dame, L.; Cugnet, D.

    We do not understand the physical mechanisms responsible for the solar irradiance cycle. Measurements of small variations in the solar diameter could have been a critical probe of the Sun 's interior stratification, telling us how and where the solar luminosity is gated or stored. We have reanalyzed the 7 years of filtregrams data (150 000 photograms and magnetograms) of the SOHO/MDI experiment. We used the maximum possible sampling compatible with full frame recording, carefully avoiding any suspicious filtregram. Going further than the previous analysis of 2 years of data by Emilio et al. (Ap. J. 543,1007, 2000), we better corrected for changes in optical aberrations and, along Turmon et al. (Ap. J., 568, 396, 2002), we reduced radius measurement errors by identifying active regions and avoiding radius measurements herein. We found that, within the limit of our noise level uncertainties (2 mas), the solar diameter could be constant over the half cycle investigated. Our results confirm the recent reanalysis of the 7 years of MDI data made by Antia (Ap. J. 590, 567, 2003), with a completely different method since using the ultra-precise frequency variation of the f-modes (fundamental modes linked to the diameter). He found (carefully removing the yearly Earth induced variations and avoiding the SOHO data gap of 1999) that the diameter is constant over the half solar cycle (radius variation are less than 0.6 km, 0.8 mas - nothing over noise level). Along Antia, we can conclude that: "If a careful analysis is performed, then it turns out that there is no evidence for any variation in the solar radius." There were no theoretical reasons for large solar radius variations and there is no observational evidence for them with consistent space observations. If changes exit, they are to be very small.

  9. Solar cycle dependence of Wind/EPACT protons, solar flares and coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Miteva, R.; Samwel, S. W.; Costa-Duarte, M. V.; Malandraki, O. E.

    2017-01-01

    The aim of this work is to compare the occurrence and overall properties of solar energetic particles (SEPs), solar flares and coronal mass ejections (CMEs) over the first seven years in solar cycles (SCs) 23 and 24. For the case of SEP events, we compiled a new proton event catalog using data from the Wind/EPACT instrument. We confirm the previously known reduction of high energy proton events in SC24 compared to the same period in SC23; our analysis shows a decrease of 25-50 MeV protons by about 30%. The similar trend is found for X to C-class solar flares which are less by about 40% and also for faster than 1000 km/s CMEs, which are reduced by about 45%. In contrast, slow CMEs are more numerous in the present solar cycle. We discuss the implications of these results for the population of SEP-productive flares and CMEs.

  10. Solar hydrogen Lyman-α variation during solar cycles 21 and 22

    NASA Astrophysics Data System (ADS)

    Kent Tobiska, W.; Pryor, Wayne R.; Ajello, Joseph M.

    1997-05-01

    A full-disk, line-integrated solar Lyman-α dataset is presented that spans two solar cycles. The dataset is created partially from AE-E and SME data that is scaled to the Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS) upwind Lyman-α sky background data which is converted to a solar surrogate. PVOUVS measurements overlap AE-E, SME, and UARS observing periods and are calibrated to UARS/SOLSTICE irradiance units at 1 AU. The scaled AE-E/SME, the SOLSTICE, and the PVOUVS surrogate data in the interim between the satellites collectively form a composite dataset with a quiet sun value of 3.0+/-0.1×1011 photons cm-2s-1 common for three solar minima and a solar maximum value of 6.75+/-0.25×1011 photons cm-2s-1 common to cycles 21 and 22.

  11. Solar hydrogen Lyman-α variation during solar cycles 21 and 22

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent; Pryor, Wayne R.; Ajello, Joseph M.

    1997-05-01

    A full-disk, line-integrated solar Lyman-α dataset is presented that spans two solar cycles. The dataset is created partially from AE-E and SME data that is scaled to the Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS) upwind Lyman-α sky background data which is converted to a solar surrogate. PVOUVS measurements overlap AE-E, SME, and UARS observing periods and are calibrated to UARS/SOLSTICE irradiance units at 1 AU. The scaled AE-E/SME, the SOLSTICE, and the PVOUVS surrogate data in the interim between the satellites collectively form a composite dataset with a quiet sun value of 3.0±0.1 × 1011 photons cm-2s-1 common for three solar minima and a solar maximum value of 6.75±0.25 × 1011 photons cm-2s-1 common to cycles 21 and 22.

  12. On the Relationship Between Solar Wind Speed, Geomagnetic Activity, and the Solar Cycle Using Annual Values

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    The aa index can be decomposed into two separate components: the leading sporadic component due to solar activity as measured by sunspot number and the residual or recurrent component due to interplanetary disturbances, such as coronal holes. For the interval 1964-2006, a highly statistically important correlation (r = 0.749) is found between annual averages of the aa index and the solar wind speed (especially between the residual component of aa and the solar wind speed, r = 0.865). Because cyclic averages of aa (and the residual component) have trended upward during cycles 11-23, cyclic averages of solar wind speed are inferred to have also trended upward.

  13. Observed Helicity of Active Regions in Solar Cycle 21

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Pevtsov, A. A.; Blehm, Z.; Smith, J. E.; Six, Frank (Technical Monitor)

    2003-01-01

    We report the results of a study of helicity in solar active regions during the peak of activity in solar cycle 21 from observations with the Marshall Space Flight Center's solar vector magnetograph. Using the force-free parameter alpha as the proxy for helicity, we calculated an average value of alpha for each of 60 active regions from a total of 449 vector magnetograms that were obtained during the period 1980 March to November. The signs of these average values of alpha were correlated with the latitude of the active regions to test the hemispheric rule of helicity that has been proposed for solar magnetic fields: negative helicity predominant in northern latitudes, positive in the southern ones. We have found that of the 60 regions that were observed, 30 obey the hemispheric rule and 30 do not.

  14. Solar powered Stirling cycle electrical generator

    NASA Technical Reports Server (NTRS)

    Shaltens, Richard K.

    1991-01-01

    Under NASA's Civil Space Technology Initiative (CSTI), the NASA Lewis Research Center is developing the technology needed for free-piston Stirling engines as a candidate power source for space systems in the late 1990's and into the next century. Space power requirements include high efficiency, very long life, high reliability, and low vibration. Furthermore, system weight and operating temperature are important. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, non-contacting gas bearings, and can be hermetically sealed. These attributes of the free-piston Stirling engine also make it a viable candidate for terrestrial applications. In cooperation with the Department of Energy, system designs are currently being completed that feature the free-piston Stirling engine for terrestrial applications. Industry teams were assembled and are currently completing designs for two Advanced Stirling Conversion Systems utilizing technology being developed under the NASA CSTI Program. These systems, when coupled with a parabolic mirror to collect the solar energy, are capable of producing about 25 kW of electricity to a utility grid. Industry has identified a niche market for dish Stirling systems for worldwide remote power application. They believe that these niche markets may play a major role in the introduction of Stirling products into the commercial market.

  15. Solar panel thermal cycling testing by solar simulation and infrared radiation methods

    NASA Technical Reports Server (NTRS)

    Nuss, H. E.

    1980-01-01

    For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

  16. Effects of Low Activity Solar Cycle on Orbital Debris Lifetime

    NASA Technical Reports Server (NTRS)

    Cable, Samual B.; Sutton, Eric K.; Lin, chin S.; Liou, J.-C.

    2011-01-01

    Long duration of low solar activity in the last solar minimum has an undesirable consequence of extending the lifetime of orbital debris. The AFRL TacSat-2 satellite decommissioned in 2008 has finally re-entered into the atmosphere on February 5th after more than one year overdue. Concerning its demise we have monitored its orbital decay and monthly forecasted Tacsat-2 re-entry since September 2010 by using the Orbital Element Prediction (OEP) model developed by the AFRL Orbital Drag Environment program. The model combines estimates of future solar activity with neutral density models, drag coefficient models, and an orbit propagator to predict satellite lifetime. We run the OEP model with solar indices forecast by the NASA Marshall Solar Activity Future Estimation model, and neutral density forecast by the MSIS-00 neutral density model. Based on the two line elements in 2010 up to mid September, we estimated at a 50% confidence level TacSat-2's re-entry time to be in early February 2011, which turned out to be in good agreement with Tacsat-2's actual re-entry date. The potential space weather effects of the coming low activity solar cycle on satellite lifetime and orbital debris population are examined. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of solar flux on the orbital debris population in the 200-600 km altitude environment. The results are discussed for developing satellite orbital drag application product.

  17. Longitudinal Waves Drive the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    2000-05-01

    In Physics Essays 12: 3-10 I explain the placement of the planets in terms of low velocity waves emitted by the sun. Evidence for the wave pulse generated near the center of the sun is indicated by the initial high latitude sunspots observed on the butterfly diagram. The wave pulse carries charge with it as observed for similar waves in plants (W-waves). For the first half cycle negative charge is carried to the surface of the sun where much of the wave pulse radiates a wave crest into space while the charge slowly redistributes itself. Meanwhile the next wave pulse carrying excess positive charge moves outward. Rotating charge determines the polarity of the sun's magnetic poles so they reverse as the pulse moves outward. The wave pulse, which interacts strongly with force fields, is guided by centripetal force and gravity so that the pulse comes out near the sun's equator. W-waves produce an automatic return wave in the vacuum so that standing waves are produced in the space around the sun providing a template for the formation and stabilization planets. W-waves are hypothesized to provide self organization for both the universe and life. See the

  18. Nonlinear data assimilation: towards a prediction of the solar cycle

    NASA Astrophysics Data System (ADS)

    Svedin, Andreas

    The solar cycle is the cyclic variation of solar activity, with a span of 9-14 years. The prediction of the solar cycle is an important and unsolved problem with implications for communications, aviation and other aspects of our high-tech society. Our interest is model-based prediction, and we present a self-consistent procedure for parameter estimation and model state estimation, even when only one of several model variables can be observed. Data assimilation is the art of comparing, combining and transferring observed data into a mathematical model or computer simulation. We use the 3DVAR methodology, based on the notion of least squares, to present an implementation of a traditional data assimilation. Using the Shadowing Filter — a recently developed method for nonlinear data assimilation — we outline a path towards model based prediction of the solar cycle. To achieve this end we solve a number of methodological challenges related to unobserved variables. We also provide a new framework for interpretation that can guide future predictions of the Sun and other astrophysical objects.

  19. Observation of lunar neutron albedo along the 24th Solar cycle

    NASA Astrophysics Data System (ADS)

    Sanin, Anton; Mitrofanov, Igor; Litvak, Maxim; Bodnarik, Julia; Boynton, William; Chin, Gordon; Evans, Larry; Golovin, Dmitry; Harshman, Karl; Livengood, Timothy; Malakhov, Alexey; Mokrousov, Maxim; McClanahan, Timothy; Sagdeev, Roald; Starr, Richard; Vostrukhin, Andrey

    2015-04-01

    It is well known that the Sun is not a steady source of radiation and demonstrates quasi-periodic variations of its activity with an average period of 11 years. The variation in solar activity yields a number of important physical effects that impact the entire heliosphere. Some of these effects are important for human life, since variations of the solar wind and the interplanetary magnetic field in the Solar System may produce variations of geomagnetic field and Van Allen radiation belts. Moreover, after strong Solar Coronal Mass Ejection events global geomagnetic storms are possible. Solar variability generates a strong modulation of the Galactic Cosmic Ray (GCR) flux inside the heliosphere and results in a modulation of the neutron albedo of the Moon and other celestial bodies that lack a strong global magnetic field. Observations of the lunar neutron albedo and its variability are quite important for future human missions on the Moon since they provide an understanding of that radiation environment on the surface and in the subsurface. We have used the data of collimated and omnidirectional epithermal neutron detectors of the Lunar Exploration Neutron Detector (LEND) gathered from September 2009 up to present. This period covers the first half of the 24th Solar cycle from period of minimum solar activity with maximum lunar neutron albedo up to high solar activity and less neutron albedo. It was found that for the observed time period, the amplitude of neutron flux drops down by a factor of ~1.7 after a maximal values observed at December 2009. We have compared LEND measurements with ongoing observations of GCR variability by neutron detectors on-board other spacecraft orbiting around Earth (BTN/ISS) and Mars (HEND/Odyssey). All neutron instruments show similar global trends and local variations. It was found that HEND on Martian orbit has detected highest amplitude of neutron flux variations (~1.8 times) and the peak of neutron flux occurred by a couple of

  20. Do solar cycles influence giant cell arteritis and rheumatoid arthritis incidence?

    SciTech Connect

    Wing, Simon; Rider, Lisa G.; Johnson, Jay R.; Miller, Federick W.; Matteson, Eric L.; Crowson, C. S.; Gabriel, S. E.

    2015-05-15

    Our objective was to examine the influence of solar cycle and geomagnetic effects on the incidence of giant cell arteritis (GCA) and rheumatoid arthritis (RA). Methods: We used data from patients with GCA (1950-2004) and RA (1955-2007) obtained from population-based cohorts. Yearly trends in age-adjusted and sex-adjusted incidence were correlated with the F10.7 index (solar radiation at 10.7 cm wavelength, a proxy for the solar extreme ultraviolet radiation) and AL index (a proxy for the westward auroral electrojet and a measure of geomagnetic activity). Fourier analysis was performed on AL, F10.7, and GCA and RA incidence rates. Results: The correlation of GCA incidence with AL is highly significant: GCA incidence peaks 0-1 year after the AL reaches its minimum (ie, auroral electrojet reaches a maximum). The correlation of RA incidence with AL is also highly significant. RA incidence rates are lowest 5-7 years after AL reaches maximum. AL, GCA and RA incidence power spectra are similar: they have a main peak (periodicity) at about 10 years and a minor peak at 4-5 years. However, the RA incidence power spectrum main peak is broader (8-11 years), which partly explains the lower correlation between RA onset and AL. The auroral electrojets may be linked to the decline of RA incidence more strongly than the onset of RA. The incidences of RA and GCA are aligned in geomagnetic latitude. Conclusions: AL and the incidences of GCA and RA all have a major periodicity of about 10 years and a secondary periodicity at 4-5 years. Geomagnetic activity may explain the temporal and spatial variations, including east-west skewness in geographic coordinates, in GCA and RA incidence, although the mechanism is unknown. Lastly, the link with solar, geospace and atmospheric parameters need to be investigated. These novel findings warrant examination in other populations and with other autoimmune diseases.

  1. Thermal Cycling of Mir Cooperative Solar Array (MCSA) Test Panels

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Scheiman, David A.

    1997-01-01

    The Mir Cooperative Solar Array (MCSA) project was a joint US/Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA is currently being used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station (ISS), which will use arrays based on the same solar cells used in the MCSA. The US supplied the photovoltaic power modules (PPMs) and provided technical and programmatic oversight while Russia provided the array support structures and deployment mechanism and built and tested the array. In order to ensure that there would be no problems with the interface between US and Russian hardware, an accelerated thermal life cycle test was performed at NASA Lewis Research Center on two representative samples of the MCSA. Over an eight-month period (August 1994 - March 1995), two 15-cell MCSA solar array 'mini' panel test articles were simultaneously put through 24,000 thermal cycles (+80 C to -100 C), equivalent to four years on-orbit. The test objectives, facility, procedure and results are described in this paper. Post-test inspection and evaluation revealed no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early as an artifact of the test and removed from consideration. The interesting nature of the performance degradation caused by this one cell, which only occurred at elevated temperatures, is discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the US solar cell modules with the Russian support structure would be able to withstand at least 24,000 thermal cycles (4 years on-orbit).

  2. Thermal cycling of Mir Cooperative Solar Array (MCSA) test panels

    SciTech Connect

    Hoffman, D.J.; Scheiman, D.A.

    1997-12-31

    The Mir Cooperative Solar Array (MCSA) project was a joint US/Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA is currently being used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station (ISS), which will use arrays based on the same solar cells used in the MCSA. The US supplied the photovoltaic power modules (PPMs) and provided technical and programmatic oversight while Russia provided the array support structures and deployment mechanism and built and tested the array. In order to ensure that there would be no problems with the interface between US and Russian hardware, an accelerated thermal life cycle test was performed at NASA Lewis Research Center on two representative samples of the MCSA. Over an eight-month period (August 1994--March 1995), two 15-cell MCSA solar array mini panel test articles were simultaneously put through 24000 thermal cycles (+80 C to {minus}100 C), equivalent to four years on-orbit. The test objectives, facility, procedure and results are described in this paper. Post-test inspection and evaluation revealed no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early as an artifact of the test and removed from consideration. The interesting nature of the performance degradation caused by this one cell, which only occurred at elevated temperatures, is discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the US solar cell modules with the Russian support structure would be able to withstand at least 24000 thermal cycles (4 years on-orbit).

  3. Solar cycle variations in the powers and damping rates of low-degree solar acoustic oscillations

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Pugh, C. E.; Nakariakov, V. M.

    2015-12-01

    Helioseismology uses the Sun's natural resonant oscillations to study the solar interior. The properties of the solar oscillations are sensitive to the Sun'2019;s magnetic activity cycle. Here we examine variations in the powers, damping rates, and energy supply rates of the most prominent acoustic oscillations in unresolved, Sun-as-a-star data, obtained by the Birmingham Solar Oscillations Network (BiSON) during solar cycles 22, 23, and the first half of 24. The variations in the helioseismic parameters are compared to the 10.7 cm flux, a well-known global proxy of solar activity. As expected the oscillations are most heavily damped and the mode powers are at a minimum at solar activity maximum. The 10.7 cm flux was linearly regressed using the fractional variations of damping rates and powers observed during cycle 23. In general, good agreement is found between the damping rates and the 10.7 cm flux. However, the linearly regressed 10.7 cm flux and fractional variation in powers diverge in cycles 22 and 24, indicating that the relationship between the mode powers and the 10.7 cm flux is not consistent from one cycle to the next. The energy supply rate of the oscillations, which is usually approximately constant, also decreases at this time. We have determined that this discrepancy is not because of the first-order bias introduced by an increase in the level of background noise or gaps in the data. Although we cannot categorically rule out an instrumental origin, the divergence observed in cycle 24, when the data were of high quality and the data coverage was over 80%, raises the possibility that the effect may be solar in origin.

  4. A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum

    NASA Astrophysics Data System (ADS)

    Liou, Kan; Wu, Chin-Chun

    2016-12-01

    Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.

  5. Solar Cycle comparison of Nitric Oxide in the lower thermosphere

    NASA Astrophysics Data System (ADS)

    Carstens, P. L.; Bailey, S. M.; Thurairajah, B.; Yonker, J. D.; Venkataramani, K.; Russell, J. M.; Hervig, M. E.

    2013-12-01

    Nitric oxide (NO) is a key minor constituent in the lower thermosphere. Of particular importance is its role in the energy balance in that altitude region. NO is produced through the reaction of excited atomic nitrogen with molecular oxygen. Thus, its production is very sensitive to those energy sources able to break the strong molecular nitrogen bond. These include solar soft X-rays and precipitating energetic particles. NO emits efficiently in the infrared and is an important cooling mechanism in the lower thermosphere. The abundance of NO is thus both a direct response to recent energy deposition as well as a key mechanism by which the upper atmosphere releases that energy. The concentration of NO should show a close relation to solar energy input. In this poster, we analyze the NO observations from the Solar Occultation for Ice Experiment (SOFIE) instrument. The SOFIE instrument was launched on-board the Aeronomy of Ice in the Mesosphere (AIM) satellite on April 25, 2007. It is currently in its sixth year of operation. SOFIE is a 16 channel differential absorption radiometer using the solar occultation technique to measure ice and environmental properties at a range of altitudes, and in particular the mesopause region. One of the constituents measured by SOFIE is NO in the mesosphere and lower thermosphere to about 130 km. The AIM orbit and the solar occultation technique confine observations to latitudes of 65 to 85 degrees in each hemisphere and varying with season. Here, we present the SOFIE observations and discuss its relationship with current levels of solar X-ray irradiance. We will further estimate the change in NO concentration (mixing ratios and densities) for the previous and current solar minimum. The statistics for this change will be presented for northern, equatorial and southern latitudes. We take the period of Jul 2008 - Jun 2009 to represent the current solar minimum between the solar cycles 23 and 24 and the period of Jan - Dec 1996 to

  6. Comparison of Voyager Shocks in Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Ashmall, Justin; Richardson, John

    2005-08-01

    Solar cycle 23 was notable for two periods of intense solar activity (or `events' as we shall hereafter refer to them): the `Bastille Day Event' of 2000 and the `Halloween Event' of 2003. In this paper we look at the signatures of the interplanetary shocks produced by these events, in particular the plasma parameters, as observed by Voyager 2 (V2) some six months after the events occurred at Sun. We compare these shocks with other large events observed by V2 during the preceding decade. We note that the plasma parameters, most notably the plasma density, are frequently not as might be expected for ``typical'' events.

  7. Solar Cycle Variation and Multipoint Studies of ICME Properties

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    2005-01-01

    The goal of the Living With a Star program is to understand the Sun-Earth connection sufficiently well that we can solve problems critical to life and society. This can most effectively be done in the short term using observations from our past and on-going programs. Not only can this approach solve some of the pressing issues but also it can provide ideas for the deployment of future spacecraft in the LWS program. The proposed effort uses data from NEAR, SOHO, Wind, ACE and Pioneer Venus in quadrature, multipoint, and solar cycle studies to study the interplanetary coronal mass ejection and its role in the magnetic flux cycle of the Sun. ICMEs are most important to the LWS objectives because the solar wind conditions associated with these structures are the most geoeffective of any solar wind phenomena. Their ability to produce strong geomagnetic disturbances arises first because of their high speed. This high speed overtakes the ambient solar wind producing a bow shock wave similar to the terrestrial bow shock. In the new techniques we develop as part of this effort we exploit this feature of ICMEs. This shocked plasma has a greater velocity, higher density and stronger magnetic field than the ambient solar wind, conditions that can enhance geomagnetic activity. The driving ICME is a large magnetic structure expanding outward in the solar wind [Gosling, 19961. The ICMEs magnetic field is generally much higher than that in the ambient solar wind and the velocity is high. The twisted nature of the magnetic field in an ICME almost ensures that sometime during the ICME conditions favorable for geomagnetic storm initiation will occur.

  8. The onset of the solar active cycle 22

    NASA Technical Reports Server (NTRS)

    Ahluwalia, H. S.

    1989-01-01

    There is a great deal of interest in being able to predict the main characteristics of a solar activity cycle (SAC). One would like to know, for instance, how large the amplitude (R sub m) of a cycle is likely to be, i.e., the annual mean of the sunspot numbers at the maximum of SAC. Also, how long a cycle is likely to last, i.e., its period. It would also be interesting to be able to predict the details, like how steep the ascending phase of a cycle is likely to be. Questions like these are of practical importance to NASA in planning the launch schedule for the low altitude, expensive spacecrafts like the Hubble Space Telescope, the Space Station, etc. Also, one has to choose a proper orbit, so that once launched the threat of an atmospheric drag on the spacecraft is properly taken into account. Cosmic ray data seem to indicate that solar activity cycle 22 will surpass SAC 21 in activity. The value of R sub m for SAC 22 may approach that of SAC 19. It would be interesting to see whether this prediction is borne out. Researchers are greatly encouraged to proceed with the development of a comprehensive prediction model which includes information provided by cosmic ray data.

  9. Solar/gas Rankine/Rankine-cycle heat pump assessment

    NASA Astrophysics Data System (ADS)

    Khalifa, H. E.; Melikian, G.

    1982-07-01

    This report contains an assessment of the technical and economic feasibility of Rankine-cycle solar-augmented gas-fired heat pumps (SAGFHP) for multi-family residential and light-commercial applications. The SAGFHP design considered in this report is based on the successful UTRC turbocompressor system which has been tested both in the laboratory and in a solar cooling installation in Phoenix. AZ. An hour-by-hour modeling of present-design SAGFHP performance in multi-family and office buildings in New York, Wisconsin, Nebraska and Oregon indicated that, even without solar augmentation, primary energy savings of up 17% and 31% could be achieved relative to advanced furnace plus electric air conditioning systems and electric heat pumps, respectively.

  10. Design and fabrication of brayton cycle solar heat receiver

    NASA Technical Reports Server (NTRS)

    Mendelson, I.

    1971-01-01

    A detail design and fabrication of a solar heat receiver using lithium fluoride as the heat storage material was completed. A gas flow analysis was performed to achieve uniform flow distribution within overall pressure drop limitations. Structural analyses and allowable design criteria were developed for anticipated environments such as launch, pressure containment, and thermal cycling. A complete heat receiver assembly was fabricated almost entirely from the refractory alloy, niobium-1% zirconium.

  11. Comparing Coronal and Heliospheric Magnetic Fields over Several Solar Cycles

    NASA Astrophysics Data System (ADS)

    Koskela, J. S.; Virtanen, I. I.; Mursula, K.

    2017-01-01

    Here we use the PFSS model and photospheric data from Wilcox Solar Observatory, SOHO/MDI, SDO/HMI, and SOLIS to compare the coronal field with heliospheric magnetic field measured at 1 au, compiled in the NASA/NSSDC OMNI 2 data set. We calculate their mutual polarity match and the power of the radial decay, p, of the radial field using different source surface distances and different number of harmonic multipoles. We find the average polarity match of 82% for the declining phase, 78%–79% for maxima, 76%–78% for the ascending phase, and 74%–76% for minima. On an average, the source surface of 3.25 RS gives the best polarity match. We also find strong evidence for solar cycle variation of the optimal source surface distance, with highest values (3.3 RS) during solar minima and lowest values (2.6 RS–2.7 RS) during the other three solar cycle phases. Raising the number of harmonic terms beyond 2 rarely improves the polarity match, showing that the structure of the HMF at 1 au is most of the time rather simple. All four data sets yield fairly similar polarity matches. Thus, polarity comparison is not affected by photospheric field scaling, unlike comparisons of the field intensity.

  12. Jovian Northern Ethane Aurora and the Solar Cycle

    NASA Technical Reports Server (NTRS)

    Kostiuk,T.; Livengood, T.; Fast, K.; Buhl, D.; Goldstein, J.; Hewagama, T.

    1999-01-01

    Thermal infrared auroral spectra from Jupiter's North polar region have been collected from 1979 to 1998 in a continuing study of long-term variability in the northern thermal IR aurora, using C2H6 emission lines near 12 microns as a probe. Data from Voyager I and 2 IRIS measurements and ground based spectral measurements were analyzed using the same model atmosphere to provide a consistent relative comparison. A retrieved equivalent mole fraction was used to compare the observed integrated emission. Short term (days), medium term (months) and long term (years) variability in the ethane emission was observed. The variability Of C2H6 emission intensities was compared to Jupiter's seasonal cycle and the solar activity cycle. A positive correlation appears to exist, with significantly greater emission and short term variability during solar maxima. Observations on 60 N latitude during increased solar activity in 1979, 1989, and most recently in 1998 show up to 5 times brighter integrated line emission of C2H6 near the north polar "hot spot" (150-210 latitude) than from the north quiescent region. Significantly lower enhancement was observed during periods of lower solar activity in 1982, 1983, 1993, and 1995. Possible sources and mechanisms for the enhancement and variability will be discussed.

  13. Solar cycle-dependent helicity transport by magnetic clouds

    NASA Astrophysics Data System (ADS)

    Lynch, B. J.; Gruesbeck, J. R.; Zurbuchen, T. H.; Antiochos, S. K.

    2005-08-01

    Magnetic clouds observed with the Wind and ACE spacecraft are fit with the static, linear force-free cylinder model to obtain estimates of the chirality, fluxes, and magnetic helicity of each event. The fastest magnetic clouds (MCs) are shown to carry the most flux and helicity. We calculate the net cumulative helicity which measures the difference in right- and left-handed helicity contained in MCs over time. The net cumulative helicity does not average to zero; rather, a strong left-handed helicity bias develops over the solar cycle, dominated by the largest events of cycle 23: Bastille Day 2000 and 28 October 2003. The majority of MCs ("slow" events, < 500 km/s) have a net cumulative helicity profile that appears to be modulated by the solar activity cycle. This is far less evident for "fast" MC events ( ≥ 500 km/s), which were disproportionately left-handed over our data set. A brief discussion about the various solar sources of CME helicity and their implication for dynamo processes is included.

  14. ON THE 'EXTENDED' SOLAR CYCLE IN CORONAL EMISSION

    SciTech Connect

    Robbrecht, E.; Wang, Y.-M.; Sheeley, N. R.; Rich, N. B. E-mail: yi.wang@nrl.navy.mi E-mail: nathan.rich@nrl.navy.mi

    2010-06-10

    Butterfly diagrams (latitude-time plots) of coronal emission show a zone of enhanced brightness that appears near the poles just after solar maximum and migrates toward lower latitudes; a bifurcation seems to occur at sunspot minimum, with one branch continuing to migrate equatorward with the sunspots of the new cycle and the other branch heading back to the poles. The resulting patterns have been likened to those seen in torsional oscillations and have been taken as evidence for an extended solar cycle lasting over {approx}17 yr. In order to clarify the nature of the overlapping bands of coronal emission, we construct butterfly diagrams from green-line simulations covering the period 1967-2009 and from 19.5 nm and 30.4 nm observations taken with the Extreme-Ultraviolet Imaging Telescope during 1996-2009. As anticipated from earlier studies, we find that the high-latitude enhancements mark the footpoint areas of closed loops with one end rooted outside the evolving boundaries of the polar coronal holes. The strong underlying fields were built up over the declining phase of the cycle through the poleward transport of active-region flux by the surface meridional flow. Rather than being a precursor of the new-cycle sunspot activity zone, the high-latitude emission forms a physically distinct, U-shaped band that curves upward again as active-region fields emerge at midlatitudes and reconnect with the receding polar-hole boundaries. We conclude that the so-called extended cycle in coronal emission is a manifestation not of early new-cycle activity, but of the poleward concentration of old-cycle trailing-polarity flux by meridional flow.

  15. Space Weather and the Ground-Level Solar Proton Events of the 23rd Solar Cycle

    NASA Astrophysics Data System (ADS)

    Shea, M. A.; Smart, D. F.

    2012-10-01

    Solar proton events can adversely affect space and ground-based systems. Ground-level events are a subset of solar proton events that have a harder spectrum than average solar proton events and are detectable on Earth's surface by cosmic radiation ionization chambers, muon detectors, and neutron monitors. This paper summarizes the space weather effects associated with ground-level solar proton events during the 23rd solar cycle. These effects include communication and navigation systems, spacecraft electronics and operations, space power systems, manned space missions, and commercial aircraft operations. The major effect of ground-level events that affect manned spacecraft operations is increased radiation exposure. The primary effect on commercial aircraft operations is the loss of high frequency communication and, at extreme polar latitudes, an increase in the radiation exposure above that experienced from the background galactic cosmic radiation. Calculations of the maximum potential aircraft polar route exposure for each ground-level event of the 23rd solar cycle are presented. The space weather effects in October and November 2003 are highlighted together with on-going efforts to utilize cosmic ray neutron monitors to predict high energy solar proton events, thus providing an alert so that system operators can possibly make adjustments to vulnerable spacecraft operations and polar aircraft routes.

  16. Solar cycle variation of the statistical distribution of the solar wind ɛ parameter and its constituent variables

    NASA Astrophysics Data System (ADS)

    Tindale, E.; Chapman, S. C.

    2016-06-01

    We use 20 years of Wind solar wind observations to investigate the solar cycle variation of the solar wind driving of the magnetosphere. For the first time, we use generalized quantile-quantile plots to compare the statistical distribution of four commonly used solar wind coupling parameters, Poynting flux, B2, the ɛ parameter, and vB, between the maxima and minima of solar cycles 23 and 24. We find the distribution is multicomponent and has the same functional form at all solar cycle phases; the change in distribution is captured by a simple transformation of variables for each component. The ɛ parameter is less sensitive than its constituent variables to changes in the distribution of extreme values between successive solar maxima. The quiet minimum of cycle 23 manifests only in lower extreme values, while cycle 24 was less active across the full distribution range.

  17. Characteristics of the 23 Cycle of Solar Activity

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Tamara

    The aim of the present study is to search for special features of the 23-d cycle of solar activity. We present results of our analysis of spectra of sunspot number W for the time intervals of spaced measurements 1964-1997 and 1996-2005 and of the Interplanetary Magnetic Field (IMF), the solar wind velocity (V) calculated on the basis of measurements near the Earth's orbit for the period 1964-1997. A method of non-linear spectral analysis named by us the Method of Global Minimum (MGM) is used. MGM allows self-consistentidentification of trends from data and non-stationary sinusoids and estimation of statistical significance of spectral components. The IMF and W spectra for the period 1964-1997 both show the solar cycle at T=10.8 yr and its higher harmonics. But spectrum of sunspot number W for the period 1996-2005 (time interval of the 23-d cycle) has not spectral component at T=10.8 yr (at confidence statistical level 95%); however, this spectrum has higher harmonics of the 10.8-yr cycle (such as sinusoid with T=146.2 day). The most powerful spectral line from the spectrum (1996-2005) has period T=16.56 yr. We show that tide forces of the planets can be a cause of periodical changes in the analyzed data. Periods of perturbed tide forces of external planets and their higher harmonics (connected with motion of the Sun relative to the mass center of the solar system) are detected in the spectra. In particular, all periods from the spectrum of W for the period 1996-2005 can be interpreted as periods of perturbed tide force of a system: Sun - a pair Jupiter-Uranus: T=16.56 yr is period of perturbed tide force of pair Jupiter-Uranus (1st planet determines shift of mass center of the Sun relative to the mass center of a system the Sunthe 1st planet; the 2nd planet determines perturbed tide force acting on the Sun). The fact that spectrum of W for the period 1996-2005 has the most power spectral components at T=16.56 and T=1.83 yr (9 harmonics of the 16.56-yr cycle

  18. IS SOLAR CYCLE 24 PRODUCING MORE CORONAL MASS EJECTIONS THAN CYCLE 23?

    SciTech Connect

    Wang, Y.-M.; Colaninno, R. E-mail: robin.colaninno@nrl.navy.mil

    2014-04-01

    Although sunspot numbers are roughly a factor of two lower in the current cycle than in cycle 23, the rate of coronal mass ejections (CMEs) appears to be at least as high in 2011-2013 as during the corresponding phase of the previous cycle, according to three catalogs that list events observed with the Large Angle and Spectrometric Coronagraph (LASCO). However, the number of CMEs detected is sensitive to such factors as the image cadence and the tendency (especially by human observers) to under-/overcount small or faint ejections during periods of high/low activity. In contrast to the total number, the total mass of CMEs is determined mainly by larger events. Using the mass measurements of 11,000 CMEs given in the manual CDAW catalog, we find that the mass loss rate remains well correlated with the sunspot number during cycle 24. In the case of the automated CACTus and SEEDS catalogs, the large increase in the number of CMEs during cycle 24 is almost certainly an artifact caused by the near-doubling of the LASCO image cadence after mid-2010. We confirm that fast CMEs undergo a much stronger solar-cycle variation than slow ones, and that the relative frequency of slow and less massive CMEs increases with decreasing sunspot number. We conclude that cycle 24 is not only producing fewer CMEs than cycle 23, but that these ejections also tend to be slower and less massive than those observed one cycle earlier.

  19. Is Solar Cycle 24 Producing More Coronal Mass Ejections Than Cycle 23?

    NASA Astrophysics Data System (ADS)

    Wang, Y.-M.; Colaninno, R.

    2014-04-01

    Although sunspot numbers are roughly a factor of two lower in the current cycle than in cycle 23, the rate of coronal mass ejections (CMEs) appears to be at least as high in 2011-2013 as during the corresponding phase of the previous cycle, according to three catalogs that list events observed with the Large Angle and Spectrometric Coronagraph (LASCO). However, the number of CMEs detected is sensitive to such factors as the image cadence and the tendency (especially by human observers) to under-/overcount small or faint ejections during periods of high/low activity. In contrast to the total number, the total mass of CMEs is determined mainly by larger events. Using the mass measurements of 11,000 CMEs given in the manual CDAW catalog, we find that the mass loss rate remains well correlated with the sunspot number during cycle 24. In the case of the automated CACTus and SEEDS catalogs, the large increase in the number of CMEs during cycle 24 is almost certainly an artifact caused by the near-doubling of the LASCO image cadence after mid-2010. We confirm that fast CMEs undergo a much stronger solar-cycle variation than slow ones, and that the relative frequency of slow and less massive CMEs increases with decreasing sunspot number. We conclude that cycle 24 is not only producing fewer CMEs than cycle 23, but that these ejections also tend to be slower and less massive than those observed one cycle earlier.

  20. Sun's Polar Magnetic Field Reversals in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Pishkalo, M. I.; Leiko, U. M.

    It is known that polar magnetic field of the Sun changes its sign at the maximum of solar cycle. These changes were called as polar field reversals. We investigated dynamics of high-latitude solar magnetic fields separately in northern and southern hemispheres. Solar polar field strength measurements from the Wilcox Solar Observatory and low-resolution synoptic magnetic maps from the SOLIS project and from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory were used. We analyzed total magnetic flux at near-polar zones, starting from 55, 60, 65, 70, 75, 80 and 85 degrees of latitude, and found time points when the total magnetic flux changed its sign. It was concluded that total magnetic flux changed its sign at first at lower latitudes and finally near the poles. Single polar magnetic field reversal was found in the southern hemisphere. The northern hemisphere was characterized by three-fold magnetic field reversal. Polar magnetic field reversals finished in northern and southern hemispheres by CR 2150 and CR 2162, respectively.

  1. Recurrence quantification analysis of two solar cycle indices

    NASA Astrophysics Data System (ADS)

    Stangalini, Marco; Ermolli, Ilaria; Consolini, Giuseppe; Giorgi, Fabrizio

    2017-02-01

    Solar activity affects the whole heliosphere and near-Earth space environment. It has been reported in the literature that the mechanism responsible for the solar activity modulation behaves like a low-dimensional chaotic system. Studying these kind of physical systems and, in particular, their temporal evolution requires non-linear analysis methods. To this regard, in this work we apply the recurrence quantification analysis (RQA) to the study of two of the most commonly used solar cycle indicators; i.e. the series of the sunspot number (SSN), and the radio flux 10.7 cm, with the aim of identifying possible dynamical transitions in the system; a task which is particularly suited to the RQA. The outcome of this analysis reveals the presence of large fluctuations of two RQA measures: namely the determinism and the laminarity. In addition, large differences are also seen between the evolution of the RQA measures of the SSN and the radio flux. That suggests the presence of transitions in the dynamics underlying the solar activity. Besides it also shows and quantifies the different nature of these two solar indices. Furthermore, in order to check whether our results are affected by dataartefacts, we have also applied the RQA to both the recently recalibrated SSN series and the previous one, unveiling the main differences between the two data sets. The results are discussed in light of the recent literature on the subject.

  2. Towards better constrained models of the solar magnetic cycle

    NASA Astrophysics Data System (ADS)

    Munoz-Jaramillo, Andres

    2010-12-01

    The best tools we have for understanding the origin of solar magnetic variability are kinematic dynamo models. During the last decade, this type of models has seen a continuous evolution and has become increasingly successful at reproducing solar cycle characteristics. The basic ingredients of these models are: the solar differential rotation -- which acts as the main source of energy for the system by shearing the magnetic field; the meridional circulation -- which plays a crucial role in magnetic field transport; the turbulent diffusivity -- which attempts to capture the effect of convective turbulence on the large scale magnetic field; and the poloidal field source -- which closes the cycle by regenerating the poloidal magnetic field. However, most of these ingredients remain poorly constrained which allows one to obtain solar-like solutions by "tuning" the input parameters, leading to controversy regarding which parameter set is more appropriate. In this thesis we revisit each of those ingredients in an attempt to constrain them better by using observational data and theoretical considerations, reducing the amount of free parameters in the model. For the meridional flow and differential rotation we use helioseismic data to constrain free parameters and find that the differential rotation is well determined, but the available data can only constrain the latitudinal dependence of the meridional flow. For the turbulent magnetic diffusivity we show that combining mixing-length theory estimates with magnetic quenching allows us to obtain viable magnetic cycles and that the commonly used diffusivity profiles can be understood as a spatiotemporal average of this process. For the poloidal source we introduce a more realistic way of modeling active region emergence and decay and find that this resolves existing discrepancies between kinematic dynamo models and surface flux transport simulations. We also study the physical mechanisms behind the unusually long minimum of

  3. Understanding Activity Cycles of Solar Type Stars with Kepler

    NASA Astrophysics Data System (ADS)

    Tovar, Guadalupe; Montet, Benjamin; Johnson, John A.

    2017-01-01

    As the era of exploring new worlds and systems advances we seek to answer the question: How common is our Sun? There is considerable evidence about the recurring activity cycles of our Sun but very little is known about the activity cycles of other stars. By calibrating the full frame images from the original Kepler mission that were taken once a month over the course of four years, we are able to do relative photometry on roughly 5 million stars. By building a model of the pixel response function we were able to achieve 0.8% precision photometry. We identify 50,000 solar type stars based on magnitude, surface gravity, and temperature cuts. We observe the relative increase and decrease in brightness of the stars indicating signs of activity cycles similar to our Sun. We continue to explore how a data driven pixel response function model could improve our precision to 0.1% photometry measurements.

  4. A new simple dynamo model for solar activity cycle

    NASA Astrophysics Data System (ADS)

    Yokoi, Nobumitsu; Schmitt, Dieter

    2015-04-01

    The solar magnetic activity cycle has been investigated in an elaborated manner with several types of dynamo models [1]. In most of the current mean-field approaches, the inhomogeneity of the large-scale flow is treated as an essential ingredient in the mean magnetic field equation whereas it is completely neglected in the turbulence equation. In this work, a new simple model for the solar activity cycle is proposed. The present model differs from the previous ones mainly in two points. First, in addition to the helicity coefficient α, we consider a term related to the cross helicity, which represents the effect of the inhomogeneous mean flow, in the turbulent electromotive force [2, 3]. Second, this transport coefficient (γ) is not treated as an adjustable parameter, but the evolution equation for γ is simultaneously solved. The basic scenario for the solar activity cycle in this approach is as follows: The toroidal field is induced by the toroidal rotation in mediation by the turbulent cross helicity. Then due to the α or helicity effect, the poloidal field is generated from the toroidal field. The poloidal field induced by the α effect produces a turbulent cross helicity whose sign is opposite to the original one (negative cross-helicity production). The cross helicity with this opposite sign induces a reversed toroidal field. Results of the eigenvalue analysis of the model equations are shown, which confirm the above scenario. References [1] Charbonneau, Living Rev. Solar Phys. 7, 3 (2010). [2] Yoshizawa, A. Phys. Fluids B 2, 1589 (1990). [3] Yokoi, N. Geophys. Astrophys. Fluid Dyn. 107, 114 (2013).

  5. Solar cycles or random processes? Evaluating solar variability in Holocene climate records.

    PubMed

    Turner, T Edward; Swindles, Graeme T; Charman, Dan J; Langdon, Peter G; Morris, Paul J; Booth, Robert K; Parry, Lauren E; Nichols, Jonathan E

    2016-04-05

    Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. (14)C or (10)Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40-100 years, and 120-140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation.

  6. Solar cycles or random processes? Evaluating solar variability in Holocene climate records

    PubMed Central

    Turner, T. Edward; Swindles, Graeme T.; Charman, Dan J.; Langdon, Peter G.; Morris, Paul J.; Booth, Robert K.; Parry, Lauren E.; Nichols, Jonathan E.

    2016-01-01

    Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. 14C or 10Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40–100 years, and 120–140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation. PMID:27045989

  7. Sources of the Slow Solar Wind During the Solar Cycle 23/24 Minimum

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Madjarska, M. S.; Karna, N.; Wiegelmann, T.; Farrugia, C.; Yu, W.; Andreeova, K.

    2016-10-01

    We investigate the characteristics and the sources of the slow ({<} 450 km s^{-1}) solar wind during the four years (2006 - 2009) of low solar activity between Solar Cycles 23 and 24. We used a comprehensive set of in-situ observations in the near-Earth solar wind ( Wind and ACE) and removed the periods when large-scale interplanetary coronal mass ejections were present. The investigated period features significant variations in the global coronal structure, including the frequent presence of low-latitude active regions in 2006 - 2007, long-lived low- and mid-latitude coronal holes in 2006 - mid-2008 and mostly the quiet Sun in 2009. We examined Carrington rotation averages of selected solar plasma, charge state, and compositional parameters and distributions of these parameters related to the quiet Sun, active region Sun, and the coronal hole Sun. While some of the investigated parameters ( e.g. speed, the C+6/C+4 and He/H ratios) show clear variations over our study period and with solar wind source type, some (Fe/O) exhibit very little changes. Our results highlight the difficulty of distinguishing between the slow solar wind sources based on the inspection of solar wind conditions.

  8. The Causes of Geomagnetic Storms During Solar Maximum

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Gonzalez, W. D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine (1852).

  9. A physical mechanism for the prediction of the sunspot number during solar cycle 21. [graphs (charts)

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

    1978-01-01

    On physical grounds it is suggested that the sun's polar field strength near a solar minimum is closely related to the following cycle's solar activity. Four methods of estimating the sun's polar magnetic field strength near solar minimum are employed to provide an estimate of cycle 21's yearly mean sunspot number at solar maximum of 140 plus or minus 20. This estimate is considered to be a first order attempt to predict the cycle's activity using one parameter of physical importance.

  10. A review of solar proton events during the 22nd solar cycle.

    PubMed

    Smart, D F; Shea, M A

    2002-01-01

    Solar cycle 22 had significant, large fluence, energetic particle events on a scale reminiscent of the 19th solar cycle. Examination of the characteristics of these large events suggests that some of the old concepts of spectral form, intensity-time envelope and energy extrapolations, used to estimate the dose from large events that occurred during previous solar cycles should be re-evaluated. There has also been a dramatic change in perspective regarding the source of solar protons observed in interplanetary space. Very large fluence events are associated with powerful fast interplanetary shocks. The elemental composition and charge state of these events is suggestive of a dominate source in the solar corona and not from a very hot plasma. Furthermore, there is a strong suggestion that the intensity-time profile observed in space is dominated by the connection of the observer to an interplanetary shock source rather than to a unique location near the surface of the sun. These concepts will be examined from the perspective of energetic particles contributing to the dose experienced by an astronaut on an interplanetary space mission.

  11. Solar and Geomagnetic Activity Relation for the Last two Solar Cycles

    NASA Astrophysics Data System (ADS)

    Kilcik, A.; Yiǧit, E.; Yurchyshyn, V.; Ozguc, A.; Rozelot, J. P.

    2017-01-01

    The long-term relationship between solar (sunspot counts in different Zurich sunspot groups, International Sunspot Number (ISSN), solar wind, and X-Ray solar flare index and geomagnetic indices (Ap and Dst) is investigated. Data sets used in this study cover a time period from January 1996 to March 2014. Our main findings are as follows: 1) The best correlation between the sunspot counts and the Ap index are obtained for the large group time series, while the other categories exhibited lower (final and medium) or no correlation at all (small). It is interesting to note that Ap index is delayed by about 13 months relatively to all sunspot count series and ISSN data. 2) The best correlation between the sunspot counts and the Dst index was as well obtained for the large AR time series. The Dst index delays with respect to the large group by about 2 months. 3) The highest correlation between the solar and geomagnetic indices were obtained between the solar wind speed and Ap and Dst indices with zero time delays (r = 0.76, r = 0.52, respectively). 4) The correlation coefficients between the geomagnetic indices (Ap, Dst) and X-Ray solar flare index (r = 0.59, r = -0.48, respectively) are a little higher than the correlation coefficients between these geomagnetic indices and ISSN (r = 0.57, r = -0.43, respectively). 5) The magnitude of all solar and geomagnetic indices (except the solar wind speed) has significantly decreased during the current solar cycle as compared to the same phase of the previous cycle.

  12. Effects of solar cycle 24 activity on WAAS navigation

    NASA Astrophysics Data System (ADS)

    Datta-Barua, Seebany; Walter, Todd; Bust, Gary S.; Wanner, William

    2014-01-01

    This paper reviews the effects of geomagnetic activity of solar cycle 24 from 2011 through mid-2013 on the Federal Aviation Administration's Wide Area Augmentation System (WAAS) navigation service in the U.S., to identify (a) major impacts and their severity compared with the previous cycle and (b) effects in new service regions of North America added since last solar cycle. We examine two cases: a storm that reduced service coverage for several hours and ionospheric scintillation that led to anomalous receiver tracking. Using the 24-25 October 2011 storm as an example, we examine WAAS operational system coverage for the conterminous U.S. (CONUS). The WAAS algorithm upgrade to ionospheric estimation, in effect since late 2011, is able to mitigate the daytime coverage loss but not the nighttime loss. We correlate WAAS availability to maps of the storm plasma generated with the data assimilative model Ionospheric Data Assimilation 4-D, which show a local nighttime corotating persistent plume of plasma extending from Florida across central CONUS. We study the effect of scintillation on 9 October 2012 on the WAAS reference station at Fairbanks, Alaska. Data from a nearby scintillation monitor in Gakona and all-sky imaging of aurora at Poker Flat corroborate the event. Anomalous receiver processing triggered by scintillation reduces accuracy at Fairbanks for a few minutes. Users experiencing similar effects would have their confidence bounds inflated, possibly trading off service continuity for safety. The activity to date in solar cycle 24 has had minor effects on WAAS service coverage, mainly occurring in Alaska and Canada.

  13. Comprehensive Analysis of Coronal Mass Ejection Mass and Energy Properties Over a Full Solar Cycle

    DTIC Science & Technology

    2010-01-01

    the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high quality images and regular cadence. This is the...observed the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high quality images and regular cadence. This is...1985) and Vourlidas et al. (2002). We discuss several aspects that emerge from the statistical analysis of such a large event sample such as solar

  14. The solar cycle dependence of the location and shape of the Venus bow shock

    NASA Technical Reports Server (NTRS)

    Zhang, T.-L.; Luhmann, J. G.; Russell, C. T.

    1990-01-01

    The Venus terminator bow shock position is monitored and it is shown that the shock radius increases as the solar cycle approaches a new maximum. It is also shown that the subsolar bow shock changes with the solar cycle, and that these positions are correlated with each other and with solar activity. It is hypothesized that, at solar minimum, the magnetic barrier is weak, and that some absorption of solar wind is to be expected.

  15. Observations of hysteresis in solar cycle variations among seven solar activity indicators

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

    We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study, we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar emission at various wavelengths.

  16. Galactic and solar radiation exposure to aircrew during a solar cycle.

    PubMed

    Lewis, B J; Bennett, L G I; Green, A R; McCall, M J; Ellaschuk, B; Butler, A; Pierre, M

    2002-01-01

    An on-going investigation using a tissue-equivalent proportional counter (TEPC) has been carried out to measure the ambient dose equivalent rate of the cosmic radiation exposure of aircrew during a solar cycle. A semi-empirical model has been derived from these data to allow for the interpolation of the dose rate for any global position. The model has been extended to an altitude of up to 32 km with further measurements made on board aircraft and several balloon flights. The effects of changing solar modulation during the solar cycle are characterised by correlating the dose rate data to different solar potential models. Through integration of the dose-rate function over a great circle flight path or between given waypoints, a Predictive Code for Aircrew Radiation Exposure (PCAIRE) has been further developed for estimation of the route dose from galactic cosmic radiation exposure. This estimate is provided in units of ambient dose equivalent as well as effective dose, based on E/H x (10) scaling functions as determined from transport code calculations with LUIN and FLUKA. This experimentally based treatment has also been compared with the CARI-6 and EPCARD codes that are derived solely from theoretical transport calculations. Using TEPC measurements taken aboard the International Space Station, ground based neutron monitoring, GOES satellite data and transport code analysis, an empirical model has been further proposed for estimation of aircrew exposure during solar particle events. This model has been compared to results obtained during recent solar flare events.

  17. Ground-Level Solar Cosmic Ray Data from Solar Cycle 19

    NASA Technical Reports Server (NTRS)

    Shea, M. A.

    2003-01-01

    The purpose of this grant was to locate, catalog, and assemble, in standard computer format, ground-level solar cosmic ray data acquired by cosmic ray detectors for selected events in the 19th solar cycle. The events for which we initially proposed to obtain these data were for the events of 23 February 1956,4 May 1960, 12 and 15 November 1960 and 18 and 20 July 1961. These were the largest events of the 19th solar cycle. However, a severe (more than 50%) reduction in the requested funding, required the work effort be limited to neutron monitor data for the 23 February 1956 event and the three major events in 1960.

  18. Climate Sensitivity and Solar Cycle Response in Climate Models

    NASA Astrophysics Data System (ADS)

    Liang, M.; Lin, L.; Tung, K. K.; Yung, Y. L.

    2011-12-01

    Climate sensitivity, broadly defined, is a measure of the response of the climate system to the changes of external forcings such as anthropogenic greenhouse emissions and solar radiation, including climate feedback processes. General circulation models provide a means to quantitatively incorporate various feedback processes, such as water-vapor, cloud and albedo feedbacks. Less attention is devoted so far to the role of the oceans in significantly affecting these processes and hence the modelled transient climate sensitivity. Here we show that the oceanic mixing plays an important role in modifying the multi-decadal to centennial oscillations of the sea surface temperature, which in turn affect the derived climate sensitivity at various phases of the oscillations. The eleven-year solar cycle forcing is used to calibrate the response of the climate system. The GISS-EH coupled atmosphere-ocean model was run twice in coupled mode for more than 2000 model years, each with a different value for the ocean eddy mixing parameter. In both runs, there is a prominent low-frequency oscillation with a period of 300-500 years, and depending on the phase of such an oscillation, the derived climate gain factor varies by a factor of 2. The run with the value of the eddy ocean mixing parameter that is half that used in IPCC AR4 study has the more realistic low-frequency variability in SST and in the derived response to the known solar-cycle forcing.

  19. Solar and interplanetary particles at 2 to 4 MEV during solar cycles 21, solar cycle variations of event sizes, and compositions

    NASA Technical Reports Server (NTRS)

    Armstrong, T. P.; Shields, J. C.; Briggs, P. R.; Eckes, S.

    1985-01-01

    In This paper 2 to 4 MeV/nucleon protons, alpha particles, and medium (CNO) nuclei in the near-Earth interplanetary medium during the years 1974 to 1981 are studied. This period contains both the solar activity minimum in 1976, and the very active onset phase of Solar Cycle 21. Characteristic compositional differences between the solar minimum and solar maximum ion populations have been investigated. Previous studies of interplanetary composition at these energies have concentrated on well-defined samples of the heliospheric medium. During flare particle events, the ambient plasma is dominated by ions accelerated in specific regions of the solar atmosphere; observation of the proton/alpha and alpha/medium ratios for flare events shows that there is marked compositional variability both during an event and from event to event suggesting the complicated nature of flare particle production and transport.

  20. Solar Thermochemical Fuels Production: Solar Fuels via Partial Redox Cycles with Heat Recovery

    SciTech Connect

    2011-12-19

    HEATS Project: The University of Minnesota is developing a solar thermochemical reactor that will efficiently produce fuel from sunlight, using solar energy to produce heat to break chemical bonds. The University of Minnesota is envisioning producing the fuel by using partial redox cycles and ceria-based reactive materials. The team will achieve unprecedented solar-to-fuel conversion efficiencies of more than 10% (where current state-of-the-art efficiency is 1%) by combined efforts and innovations in material development, and reactor design with effective heat recovery mechanisms and demonstration. This new technology will allow for the effective use of vast domestic solar resources to produce precursors to synthetic fuels that could replace gasoline.

  1. An Educational Display of the Solar Magnetic Cycle: Year 2

    NASA Astrophysics Data System (ADS)

    Jones, H. P.; Gearen, M. V.; Jacoby, S. H.

    1999-05-01

    We are developing an educational module to improve student and public understanding of the Sun's magnetic cycle. The instructional package features a CDROM compatible with most personal computers available in the home or classroom with a day-by-day record of an entire magnetic cycle as recorded in magnetograms from the National Solar Observatory Kitt Peak Vacuum Telescope (NSO/KPVT) near Tucson, AZ. These data have in fact been crucial to developing our present understanding of the solar cycle and its terrestrial effects. In the second year of the project, we have loaded the data to compact disks both as individual "gif" files for inspection and analysis and as QuickTime movies, have prepared the first version of the accompanying textual material, and are developing macros to aid extraction of information from the data for various laboratory exercises. We will display samples of these images and movies, and will furnish copies of the compact disks and accompanying textual material for testing and comment.

  2. Solar cycle effect on atmospheric carbon dioxide levels. Final report

    SciTech Connect

    Kirk, B.L.; Rust, B.W.

    1983-01-01

    The authors present a causal time-series model for the Mauna Loa atmospheric CO2 record which supersedes a mathematical model consisting of four effects represented by exponential and sine functions. One effect is a 142-month oscillation which trails the sunspot numbers by exactly a quarter-cycle. This suggests that solar activity affects the rate of change in the atmospheric CO2 abundance. The new model replaces the mathematical functions with four measured time series representing proposed physical causes and reduces the number of adjustable parameters from 13 to 5 with no significant deterioration in the fit. The authors present evidence that solar activity affects the CO2 abundance through variations in ocean temperature or circulation.

  3. Solar Cycle Variations of Fe-rich SEP Events

    NASA Astrophysics Data System (ADS)

    Cane, H. V.; Richardson, I. G.

    2006-12-01

    An investigation of the characteristics of large solar energetic particle (SEP) events with >25 MeV/nuc event- -averaged Fe/O above 0.5 shows that such events have a rapid rise to maximum intensity and little evidence of particle acceleration at the passage of an interplanetary shock in this energy range. We explore the reasons why such events were not seen by near--Earth spacecraft in 2004 and 2005. One reason, that we have already documented, is that fast shocks (transit speeds above 1000 km/s) are relatively more common after solar maximum. The disappearance of Fe--rich events late in Cycle 23 has been used by Tylka et al. (2006) to argue for the absence of flare particles both as seed particles for shocks and as direct contributors to large SEP events. However, such arguments ignore the fact that there were no events with the other characteristics of Fe-rich events.

  4. Solar photospheric network properties and their cycle variation

    SciTech Connect

    Thibault, K.; Charbonneau, P.; Béland, M. E-mail: paulchar@astro.umontreal.ca-b

    2014-11-20

    We present a numerical simulation of the formation and evolution of the solar photospheric magnetic network over a full solar cycle. The model exhibits realistic behavior as it produces large, unipolar concentrations of flux in the polar caps, a power-law flux distribution with index –1.69, a flux replacement timescale of 19.3 hr, and supergranule diameters of 20 Mm. The polar behavior is especially telling of model accuracy, as it results from lower-latitude activity, and accumulates the residues of any potential modeling inaccuracy and oversimplification. In this case, the main oversimplification is the absence of a polar sink for the flux, causing an amount of polar cap unsigned flux larger than expected by almost one order of magnitude. Nonetheless, our simulated polar caps carry the proper signed flux and dipole moment, and also show a spatial distribution of flux in good qualitative agreement with recent high-latitude magnetographic observations by Hinode. After the last cycle emergence, the simulation is extended until the network has recovered its quiet Sun initial condition. This permits an estimate of the network relaxation time toward the baseline state characterizing extended periods of suppressed activity, such as the Maunder Grand Minimum. Our simulation results indicate a network relaxation time of 2.9 yr, setting 2011 October as the soonest the time after which the last solar activity minimum could have qualified as a Maunder-type Minimum. This suggests that photospheric magnetism did not reach its baseline state during the recent extended minimum between cycles 23 and 24.

  5. Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2007-01-01

    We present results of a statistical investigation of 99 magnetic clouds (MCs) observed during 1995-2005. The MC-associated coronal mass ejections (CMEs) are faster and wider on the average and originate within +/-30deg from the solar disk center. The solar sources of MCs also followed the butterfly diagram. The correlation between the magnetic field strength and speed of MCs was found to be valid over a much wider range of speeds. The number of south-north (SN) MCs was dominant and decreased with solar cycle, while the number of north-south (NS) MCs increased confirming the odd-cycle behavior. Two-thirds of MCs were geoeffective; the Dst index was highly correlated with speed and magnetic field in MCs as well as their product. Many (55%) fully northward (FN) MCs were geoeffective solely due to their sheaths. The non-geoeffective MCs were slower (average speed approx. 382 km/s), had a weaker southward magnetic field (average approx. -5.2nT), and occurred mostly during the rise phase of the solar activity cycle.

  6. Intermittency of the Solar Magnetic Field and Solar Magnetic Activity Cycle

    NASA Astrophysics Data System (ADS)

    Shibalova, A. S.; Obridko, V. N.; Sokoloff, D. D.

    2017-03-01

    Small-scale solar magnetic fields demonstrate features of fractal intermittent behavior, which requires quantification. For this purpose we investigate how the observational estimate of the solar magnetic flux density B depends on resolution D in order to obtain the scaling ln BD = - k ln D +a in a reasonably wide range. The quantity k demonstrates cyclic variations typical of a solar activity cycle. In addition, k depends on the magnetic flux density, i.e. the ratio of the magnetic flux to the area over which the flux is calculated, at a given instant. The quantity a demonstrates some cyclic variation, but it is much weaker than in the case of k. The scaling obtained generalizes previous scalings found for the particular cycle phases. The scaling is typical of fractal structures. In our opinion, the results obtained trace small-scale action in the solar convective zone and its coexistence with the conventional large-scale solar dynamo based on differential rotation and mirror-asymmetric convection.

  7. On the reduced geoeffectiveness of solar cycle 24: A moderate storm perspective

    NASA Astrophysics Data System (ADS)

    Selvakumaran, R.; Veenadhari, B.; Akiyama, S.; Pandya, Megha; Gopalswamy, N.; Yashiro, S.; Kumar, Sandeep; Mäkelä, P.; Xie, H.

    2016-09-01

    The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (ɛ) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.

  8. The solar corona through the sunspot cycle: preparing for the August 21, 2017, total solar eclipse

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Seaton, Daniel; Rusin, Vojtech

    2017-01-01

    We discuss the evolution of the solar corona as seen at eclipses through the solar-activity cycle. In particular, we discuss the variations of the overall shape of the corona through the relative proportions of coronal streamers at equatorial and other latitudes vs. polar plumes. We analyze the two coronal mass ejections that we observed from Gabon at the 2013 total solar eclipse and how they apparently arose from polar crown filaments, one at each pole. We describe the change in the Ludendorff flattening index from solar maximum in one hemisphere as of the 2013 eclipse through the 2015 totality's corona we observed from Svalbard and, with diminishing sunspot and other magnetic activity in each hemisphere, through the 2016 corona we observed from Ternate, Indonesia.We discuss our observational plans for the August 21, 2017, total solar eclipse from our main site in Salem, Oregon, and subsidiary sites in Madras, OR; Carbondale, IL; and elsewhere, our main site chosen largely by its favorable rating in cloudiness statistics. We discuss the overlapping role of simultaneous spacecraft observations, including those expected not only from NASA's SDO, ESA's SWAP on PROBA2, and NRL/NASA/ESA's LASCO on SOHO but also from the new SUVI (Solar Ultraviolet Imager) aboard NOAA's GOES-R satellite, scheduled as of this writing to have been launched by the time of this January 2017 meeting.Our research on the 2013 and 2015 total solar eclipses was supported by grants from the Committee for Research and Exploration of the National Geographic Society (NG-CRE). Our research on the 2017 total solar eclipse is supported by both NG-CRE and the Solar Terrestrial Program of the Atmospheric and Geospace Sciences Division of the National Science Foundation.

  9. Structure and sources of solar wind in the growing phase of 24th solar cycle

    NASA Astrophysics Data System (ADS)

    Slemzin, Vladimir; Goryaev, Farid; Shugay, Julia; Rodkin, Denis; Veselovsky, Igor

    2015-04-01

    We present analysis of the solar wind (SW) structure and its association with coronal sources during the minimum and rising phase of 24th solar cycle (2009-2011). The coronal sources prominent in this period - coronal holes, small areas of open magnetic fields near active regions and transient sources associated with small-scale solar activity have been investigated using EUV solar images and soft X-ray fluxes obtained by the CORONAS-Photon/TESIS/Sphinx, PROBA2/SWAP, Hinode/EIS and AIA/SDO instruments as well as the magnetograms obtained by HMI/SDO. It was found that at solar minimum (2009) velocity and magnetic field strength of high speed wind (HSW) and transient SW from small-scale flares did not differ significantly from those of the background slow speed wind (SSW). The major difference between parameters of different SW components was seen in the ion composition represented by the C6/C5, O7/O6, Fe/O ratios and the mean charge of Fe ions. With growing solar activity, the speed of HSW increased due to transformation of its sources - small-size low-latitude coronal holes into equatorial extensions of large polar holes. At that period, the ion composition of transient SW changed from low-temperature to high-temperature values, which was caused by variation of the source conditions and change of the recombination/ionization rates during passage of the plasma flow through the low corona. However, we conclude that criteria of separation of the SW components based on the ion ratios established earlier by Zhao&Fisk (2009) for higher solar activity are not applicable to the extremely weak beginning of 24th cycle. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement eHeroes (project n° 284461, www.eheroes.eu).

  10. The long-period of the real moon-solar cycle

    NASA Astrophysics Data System (ADS)

    Mikhalchuk, V. V.

    2014-10-01

    The long-period moon-solar cycle consisting of an integer of 19-years cycles are established. The secular correction is obtained, permitting to increase the exactitude of a calculation of age of Moon, and the universal formula for a calculation of lunar number in various aspects of moon-solar cycles.

  11. High-Energy Solar Particle Events in Cycle 24

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Yashiro, S.; Xie, H.; Akiyama, S.; Thakur, N.

    2015-01-01

    The Sun is already in the declining phase of cycle 24, but the paucity of high-energy solar energetic particle (SEP) events continues with only two ground level enhancement (GLE) events as of March 31, 2015. In an attempt to understand this, we considered all the large SEP events of cycle 24 that occurred until the end of 2014. We compared the properties of the associated CMEs with those in cycle 23. We found that the CME speeds in the sky plane were similar, but almost all those cycle-24 CMEs were halos. A significant fraction of (16%) of the frontside SEP events were associated with eruptive prominence events. CMEs associated with filament eruption events accelerate slowly and attain peak speeds beyond the typical GLE release heights. When we considered only western hemispheric events that had good connectivity to the CME nose, there were only 8 events that could be considered as GLE candidates. One turned out to be the first GLE event of cycle 24 (2012 May 17). In two events, the CMEs were very fast (>2000 km/s) but they were launched into a tenuous medium (high Alfven speed). In the remaining five events, the speeds were well below the typical GLE CME speed (2000 km/s). Furthermore, the CMEs attained their peak speeds beyond the typical heights where GLE particles are released. We conclude that several factors contribute to the low rate of high-energy SEP events in cycle 24: (i) reduced efficiency of shock acceleration (weak heliospheric magnetic field), (ii) poor latitudinal and longitudinal connectivity), and (iii) variation in local ambient conditions (e.g., high Alfven speed).

  12. Ionospheric response to great geomagnetic storms during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

    The analyses of ionospheric responses due to great geomagnetic storms i.e. Dst index < 350 nT that occurred during solar cycle 23 are presented. The GPS Total Electron Content (TEC) and ionosonde data over Southern and Northern Hemisphere mid-latitudes were used to study the ionospheric responses. A geomagnetic latitude region of ±30° to ±46° within a longitude sector of 15° to 40° was considered. Using a criteria of Dst < -350 nT, there were only four great storm periods (29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004) in solar cycle 23. Analysis has shown that ionospheric dynamics during these disturbed conditions could be due to a number of dynamic and electrodynamics processes in both Hemispheres. In some instances the ionosphere responds differently to the same storm condition in both Hemispheres. Physical mechanisms related to (but not limited to) composition changes and electric fields will be discussed.

  13. Solar energy demand (SED) of commodity life cycles.

    PubMed

    Rugani, Benedetto; Huijbregts, Mark A J; Mutel, Christopher; Bastianoni, Simone; Hellweg, Stefanie

    2011-06-15

    The solar energy demand (SED) of the extraction of 232 atmospheric, biotic, fossil, land, metal, mineral, nuclear, and water resources was quantified and compared with other energy- and exergy-based indicators. SED represents the direct and indirect solar energy required by a product or service during its life cycle. SED scores were calculated for 3865 processes, as implemented in the Ecoinvent database, version 2.1. The results showed that nonrenewable resources, and in particular minerals, formed the dominant contribution to SED. This large share is due to the indirect solar energy required to produce these resource inputs. Compared with other energy- and exergy-based indicators, SED assigns higher impact factors to minerals and metals and smaller impact factors to fossil energetic resources, land use, and nuclear energy. The highest differences were observed for biobased and renewable energy generation processes, whose relative contribution of renewable resources such as water, biomass, and land occupation was much lower in SED than in energy- and exergy-based indicators.

  14. SOLAR CYCLE VARIATION OF SOUND SPEED INSIDE THE SUN

    SciTech Connect

    Mullan, D. J.; MacDonald, J.; Rabello-Soares, M. C.

    2012-08-10

    Empirical radial profiles of the changes in sound speed inside the Sun between solar minimum and solar maximum have been extracted from Michelson Doppler Imager data by Baldner and Basu and Rabello-Soares. Here, we compare these results with the theoretical radial profiles predicted by a model of magnetic inhibition of convective onset: In the model, the degree of magnetic inhibition is characterized by a parameter {delta}, which is essentially the ratio of magnetic pressure to gas pressure. We find that the theoretical profiles overlap significantly with the empirical results in the outer half of the convection zone. But differences in the deeper layers indicate that the model needs to be modified there. The main result that emerges in the present comparison is that the value of {delta} must be larger near the surface than at great depth. A secondary result is that, in the course of the solar cycle, the magnetic field magnitude at the base of the convection zone may be out of phase with the field near the surface.

  15. Solar Wind Plasma Flows and Space Weather Aspects Recent Solar Cycle

    NASA Astrophysics Data System (ADS)

    Kaushik, Sonia; Kaushik, Subhash Chandra

    2016-07-01

    Solar transients are responsible for initiating short - term and long - term variations in earth's magnetosphere. These variations are termed as geomagnetic disturbances, and driven by the interaction of solar wind features with the geo-magnetosphere. The strength of this modulation process depends upon the magnitude and orientation of the Interplanetary Magnetic Field and solar wind parameters. These interplanetary transients are large scale structures containing plasma and magnetic field expelled from the transient active regions of solar atmosphere. As they come to interplanetary medium the interplanetary magnetic field drape around them. This field line draping was thought as possible cause of the characteristic eastward deflection and giving rise to geomagnetic activities as well as a prime factor in producing the modulation effects in the near Earth environment. The Solar cycle 23 has exhibited the unique extended minima and peculiar effects in the geomagnetosphere. Selecting such transients, occurred during this interval, an attempt has been made to determine quantitative relationships of these transients with solar/ interplanetary and Geophysical Parameters. In this work we used hourly values of IMF data obtained from the NSSD Center. The analysis mainly based on looking into the effects of these transients on earth's magnetic field. The high-resolution data IMF Bz and solar wind data obtained from WDC-A, through its omniweb, available during the selected period. Dst and Ap obtained from WDC-Kyoto are taken as indicator of geomagnetic activities. It is found that Dst index, solar wind velocity, proton temperature and the Bz component of magnetic field have higher values and increase just before the occurrence of these events. Larger and varying magnetic field mainly responsible for producing the short-term changes in geomagnetic intensity are observed during these events associated with coronal holes.

  16. Solar Irradiance from 165 to 400 nm in 2008 and UV Variations in Three Spectral Bands During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Bolsée, D.; Damé, L.; Hauchecorne, A.; Pereira, N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thiéblemont, R.

    2016-12-01

    Accurate measurements of the solar spectral irradiance (SSI) and its temporal variations are of primary interest to better understand solar mechanisms, and the links between solar variability and Earth's atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to carry out SSI measurements from 165 to 3088 nm. We focus here on the ultraviolet (UV) part of the measured solar spectrum (wavelengths less than 400 nm) because the UV part is potentially important for understanding the solar forcing of Earth's atmosphere and climate. We present here SOLAR/SOLSPEC UV data obtained since 2008, and their variations in three spectral bands during Solar Cycle 24. They are compared with previously reported UV measurements and model reconstructions, and differences are discussed.

  17. The response of ozone to solar proton events during solar cycle 21 - The observations

    NASA Technical Reports Server (NTRS)

    Mcpeters, R. D.; Jackman, C. H.

    1985-01-01

    It is pointed out that during a solar proton event (SPE), large numbers of high-energy protons penetrate the earth's mesosphere and upper stratosphere and perturb the normal chemistry by ionizing molecules and changing the balance of odd nitrogen, oxygen, and hydrogen. Changes in ozone caused by an SPE are produced very rapidly, typically in a matter of hours, and are confined to a limited geographic area, the region above 60 deg geomagnetic latitude. In this paper, an analysis is reported of the response of ozone to the significant SPE's in solar cycle 21 from the Nimbus 7 launch in October 1978 to date, using data from the solar backscattered ultraviolet instrument (SBUV). Ozone data during 15 SPE's were examined. It was found that ozone depletion occurred during SPE's on at least five dates.

  18. Unusual Polar Conditions in Solar Cycle 24 and Their Implications for Cycle 25

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko

    2016-05-01

    We report on the prolonged solar-maximum conditions until late 2015 at the north-polar region of the Sun indicated by the occurrence of high-latitude prominence eruptions (PEs) and microwave brightness temperature close to the quiet-Sun level. These two aspects of solar activity indicate that the polarity reversal was completed by mid-2014 in the south and late 2015 in the north. The microwave brightness in the south-polar region has increased to a level exceeding the level of the Cycle 23/24 minimum, but just started to increase in the north. The north-south asymmetry in the polarity reversal has switched from that in Cycle 23. These observations lead us to the hypothesis that the onset of Cycle 25 in the northern hemisphere is likely to be delayed with respect to that in the southern hemisphere. We find that the unusual condition in the north is a direct consequence of the arrival of poleward surges of opposite polarity from the active region belt. We also find that multiple rush-to-the-pole episodes were indicated by the PE locations that lined up at the boundary between opposite-polarity surges. The high-latitude PEs occurred in the boundary between the incumbent polar flux and the insurgent flux of opposite polarity.

  19. Do solar cycles influence giant cell arteritis and rheumatoid arthritis incidence?

    DOE PAGES

    Wing, Simon; Rider, Lisa G.; Johnson, Jay R.; ...

    2015-05-15

    Our objective was to examine the influence of solar cycle and geomagnetic effects on the incidence of giant cell arteritis (GCA) and rheumatoid arthritis (RA). Methods: We used data from patients with GCA (1950-2004) and RA (1955-2007) obtained from population-based cohorts. Yearly trends in age-adjusted and sex-adjusted incidence were correlated with the F10.7 index (solar radiation at 10.7 cm wavelength, a proxy for the solar extreme ultraviolet radiation) and AL index (a proxy for the westward auroral electrojet and a measure of geomagnetic activity). Fourier analysis was performed on AL, F10.7, and GCA and RA incidence rates. Results: The correlationmore » of GCA incidence with AL is highly significant: GCA incidence peaks 0-1 year after the AL reaches its minimum (ie, auroral electrojet reaches a maximum). The correlation of RA incidence with AL is also highly significant. RA incidence rates are lowest 5-7 years after AL reaches maximum. AL, GCA and RA incidence power spectra are similar: they have a main peak (periodicity) at about 10 years and a minor peak at 4-5 years. However, the RA incidence power spectrum main peak is broader (8-11 years), which partly explains the lower correlation between RA onset and AL. The auroral electrojets may be linked to the decline of RA incidence more strongly than the onset of RA. The incidences of RA and GCA are aligned in geomagnetic latitude. Conclusions: AL and the incidences of GCA and RA all have a major periodicity of about 10 years and a secondary periodicity at 4-5 years. Geomagnetic activity may explain the temporal and spatial variations, including east-west skewness in geographic coordinates, in GCA and RA incidence, although the mechanism is unknown. Lastly, the link with solar, geospace and atmospheric parameters need to be investigated. These novel findings warrant examination in other populations and with other autoimmune diseases.« less

  20. Analysis of Low Temperature Organic Rankine Cycles for Solar Applications

    NASA Astrophysics Data System (ADS)

    Li, Yunfei

    The present work focuses on Organic Rankine Cycle (ORC) systems and their application to low temperature waste heat recovery, combined heat and power as well as off-grid solar power generation applications. As CO_2 issues come to the fore front and fossil fuels become more expensive, interest in low grade heat recovery has grown dramatically in the past few years. Solar energy, as a clean, renewable, pollution-free and sustainable energy has great potential for the use of ORC systems. Several ORC solutions have been proposed to generate electricity from low temperature sources. The ORC systems discussed here can be applied to fields such as solar thermal, biological waste heat, engine exhaust gases, small-scale cogeneration, domestic boilers, etc. The current work presents a thermodynamic and economic analysis for the use of ORC systems to convert solar energy or low exergy energy to generate electrical power. The organic working fluids investigated here were selected to investigate the effect of the fluid saturation temperature on the performance of ORCs. The working fluids under investigation are R113, R245fa, R123, with boiling points between 40°C and 200°C at pressures from 10 kPa to 10 MPa. Ambient temperature air at 20oC to 30oC is utilized as cooling resource, and allowing for a temperature difference 10°C for effective heat transfer. Consequently, the working fluids are condensed at 40°C. A combined first- and second-law analysis is performed by varying some system independent parameters at various reference temperatures. The present work shows that ORC systems can be viable and economical for the applications such as waste heat use and off-grid power generation even though they are likely to be more expensive than grid power.

  1. Observations of Solar Cycle Variations in UV Spectral Irradiance Since 1978

    NASA Astrophysics Data System (ADS)

    Cebula, R. P.; Deland, M. T.

    2010-12-01

    The spectrally resolved amplitude of solar UV irradiance variations over a solar cycle is an important parameter for estimating long-term changes in the Earth’s climate system. Satellite measurements of solar UV variability have been made by at least eight different instruments since 1978, covering both rising and declining phases of solar activity. Determining solar cycle variations from these data sets requires careful consideration of both time-dependent and wavelength-dependent uncertainties for each instrument. We have previously presented irradiance variation results for solar cycles 21, 22, and 23 using spectral irradiance data from Nimbus-7 SBUV, SME, NOAA-9 SBUV/2, NOAA-11 SBUV/2, UARS SUSIM, and UARS SOLSTICE. These results have shown consistent solar cycle irradiance changes within instrumental uncertainties, and also show the same relative spectral dependence for both short-term (rotational) and long-term (solar cycle) variations. In this work, we compare these results to recent UV irradiance data from the SORCE SIM and SORCE SOLSTICE instruments covering the declining phase of Cycle 23. Implementation of the SORCE solar data in atmospheric models leads to substantial changes in stratospheric heating and ozone concentrations compared to previous calculations. We will examine the agreement in solar cycle behavior between different irradiance data sets for their respective time periods, as well as the agreement with proxy model predictions of solar activity.

  2. Evolution of global distribution of the solar wind from cycle 23 to the early phase of cycle 24

    NASA Astrophysics Data System (ADS)

    Tokumaru, Munetoshi; Fujiki, Ken'ichi; Kojima, Masayoshi

    2013-06-01

    Interplanetary scintillation (IPS) observations made with the 327-MHz multi-station system of the Solar-Terrestrial Environment Laboratory (STEL) of Nagoya University are used to investigate long-term evolution of the global solar wind structure. Here, we focus on the recent trend in our data (up to 2011), since peculiar aspects of the cycle 24 have been reported from earlier studies. The IPS data demonstrate that the solar wind systematically changes its global structure with the solar activity cycle, and also that there is some distinct differences in the solar wind structure between the current and past cycles. The fractional area of the fast wind on the source surface significantly increases at low latitudes in the extended minimum between cycle 23 and 24, as compared with that between cycle 22 and 23. This fact is consistent with a marked growth of equatorial coronal holes during the cycle 24. A comparison with magnetograph data of Wilcox Solar Observatory reveals that polar fields have a positive (negative) correlation with fast (slow) wind areas. We find that the solar wind structure in the cycle 24 changes with polar fields following a slightly different track from that of the past cycle. This discrepancy is ascribed to an effect of higher-order moments of the Sun's magnetic field. Another important point revealed from our IPS observations is that solar wind density fluctuations distinctly drop after the extended minimum. This is consistent with a significant reduction in solar wind density observed by in situ measurements during the extended minimum, while our IPS data show that this reduction continues until 2011.

  3. Thermal stress cycling of GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Janousek, B. K.; Francis, R. W.; Wendt, J. P.

    A thermal cycling experiment was performed on GaAs solar cells to establish the electrical and structural integrity of these cells under the temperature conditions of a simulated low-Earth orbit of 3-year duration. Thirty single junction GaAs cells were obtained and tests were performed to establish the beginning-of-life characteristics of these cells. The tests consisted of cell I-V power output curves, from which were obtained short-circuit current, open circuit voltage, fill factor, and cell efficiency, and optical micrographs, spectral response, and ion microprobe mass analysis (IMMA) depth profiles on both the front surfaces and the front metallic contacts of the cells. Following 5,000 thermal cycles, the performance of the cells was reexamined in addition to any factors which might contribute to performance degradation. It is established that, after 5,000 thermal cycles, the cells retain their power output with no loss of structural integrity or change in physical appearance.

  4. XMM-Newton detects X-ray 'solar cycle' in distant star

    NASA Astrophysics Data System (ADS)

    2004-05-01

    The Sun as observed by SOHO hi-res Size hi-res: 708 Kb The Sun as observed by SOHO The Sun as observed by the ESA/NASA SOHO observatory near the minimum of the solar cycle (left) and near its maximum (right). The signs of solar activity near the maximum are clearly seen. New XMM-Newton observations suggest that this behaviour may be typical of stars like the Sun, such as HD 81809 in the constellation Hydra. Solar flare - 4 November 2003 The huge flare produced on 4 November 2003 This image of the Sun, obtained by the ESA/NASA SOHO observatory, shows the powerful X-ray flare that took place on 4 November 2003. The associated coronal mass ejection, coming out of the Sun at a speed of 8.2 million kilometres per hour, hit the Earth several hours later and caused disruptions to telecommunication and power distribution lines. New XMM-Newton observations suggest that this behaviour may be typical of stars like the Sun, such as HD 81809 in the constellation Hydra. Since the time Galileo discovered sunspots, in 1610, astronomers have measured their number, size and location on the disc of the Sun. Sunspots are relatively cooler areas on the Sun that are observed as dark patches. Their number rises and falls with the level of activity of the Sun in a cycle of about 11 years. When the Sun is very active, large-scale phenomena take place, such as the flares and coronal mass ejections observed by the ESA/NASA solar observatory SOHO. These events release a large amount of energy and charged particles that hit the Earth and can cause powerful magnetic storms, affecting radio communications, power distribution lines and even our weather and climate. During the solar cycle, the X-ray emission from the Sun varies by a large amount (about a factor of 100) and is strongest when the cycle is at its peak and the surface of the Sun is covered by the largest number of spots. ESA's X-ray observatory, XMM-Newton, has now shown for the first time that this cyclic X-ray behaviour is common to

  5. Sources of Geomagnetic Activity during Nearly Three Solar Cycles (1972-2000)

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.; Cliver, E. W.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We examine the contributions of the principal solar wind components (corotating highspeed streams, slow solar wind, and transient structures, i.e., interplanetary coronal mass ejections (CMEs), shocks, and postshock flows) to averages of the aa geomagnetic index and the interplanetary magnetic field (IMF) strength in 1972-2000 during nearly three solar cycles. A prime motivation is to understand the influence of solar cycle variations in solar wind structure on long-term (e.g., approximately annual) averages of these parameters. We show that high-speed streams account for approximately two-thirds of long-term aa averages at solar minimum, while at solar maximum, structures associated with transients make the largest contribution (approx. 50%), though contributions from streams and slow solar wind continue to be present. Similarly, high-speed streams are the principal contributor (approx. 55%) to solar minimum averages of the IMF, while transient-related structures are the leading contributor (approx. 40%) at solar maximum. These differences between solar maximum and minimum reflect the changing structure of the near-ecliptic solar wind during the solar cycle. For minimum periods, the Earth is embedded in high-speed streams approx. 55% of the time versus approx. 35% for slow solar wind and approx. 10% for CME-associated structures, while at solar maximum, typical percentages are as follows: high-speed streams approx. 35%, slow solar wind approx. 30%, and CME-associated approx. 35%. These compositions show little cycle-to-cycle variation, at least for the interval considered in this paper. Despite the change in the occurrences of different types of solar wind over the solar cycle (and less significant changes from cycle to cycle), overall, variations in the averages of the aa index and IMF closely follow those in corotating streams. Considering solar cycle averages, we show that high-speed streams account for approx. 44%, approx. 48%, and approx. 40% of the solar

  6. Properties of Magnetic Tongues over a Solar Cycle

    NASA Astrophysics Data System (ADS)

    Poisson, Mariano; Démoulin, Pascal; López Fuentes, Marcelo; Mandrini, Cristina H.

    2016-08-01

    The photospheric spatial distribution of the main magnetic polarities of bipolar active regions (ARs) present during their emergence deformations are known as magnetic tongues. They are attributed to the presence of twist in the toroidal magnetic-flux tubes that form the ARs. The aim of this article is to study the twist of newly emerged ARs from the evolution of magnetic tongues observed in photospheric line-of-sight magnetograms. We apply the procedure described by Poisson et al. ( Solar Phys. 290, 727, 2015a) to ARs observed over the full Solar Cycle 23 and the beginning of Cycle 24. Our results show that the hemispherical rule obtained using the tongues as a proxy of the twist has a weak sign dominance (53 % in the southern hemisphere and 58 % in the northern hemisphere). By defining the variation of the tongue angle, we characterize the strength of the magnetic tongues during different phases of the AR emergence. We find that there is a tendency of the tongues to be stronger during the beginning of the emergence and to become weaker as the AR reaches its maximum magnetic flux. We compare this evolution with the emergence of a toroidal flux-rope model with non-uniform twist. The variety of evolution of the tongues in the analyzed ARs can only be reproduced when using a broad range of twist profiles, in particular having a large variety of twist gradients in the direction vertical to the photosphere. Although the analytical model used is a special case, selected to minimize the complexity of the problem, the results obtained set new observational constraints to theoretical models of flux-rope emergence that form bipolar ARs.

  7. Analysis of Polar Reversals of Solar Cycle 22 and 23

    NASA Astrophysics Data System (ADS)

    Ettinger, Sophie

    2015-01-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of synoptic magnetograms, one to three activity complexes (systems of active regions) were identified in each reversal as the main cause of polar field reversals in each cycle. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes was found to correlate well in time with the polar field changes. In each case significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This result indicates the importance of the Joy's law tilt and consequent high-latitude polarity bias in polar reversals.This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  8. Geoeffectiveness of solar eruptions during the rising phase of solar cycle 24

    NASA Astrophysics Data System (ADS)

    Bisht, Hema; Pande, Bimal; Chandra, Ramesh; Pande, Seema

    2017-02-01

    This paper presents a statistical analysis of different parameters responsible for the geoeffectiveness of solar eruptions during the rising phase of solar cycle 24. We have selected 33 halo CME events from the beginning of the current solar cycle 24 (2009-2013). The levels of geomagnetic activity are categorized into two groups based on the observed minimum Dst index, i.e., moderate (-100 nT < Dst ≤ -50 nT) and intense (Dst ≤ -100nT). The parameters are represented graphically and analyzed statistically. The Spearman rank correlation coefficient between Dst index and CME speed is 0.02 with a P-value 0.91 (much higher than 0.05) and between Dst index and X-ray flux of flares is 0.13 with a P-value 0.48 (higher than 0.05), which shows that high speed CMEs and big flares are not the effective and significant parameters for geoeffectiveness of these selected halo events. The Spearman rank correlation coefficient between CME speed and X-ray flux is better, i.e., 0.38 and the P-value is equal to 0.03 (less than 0.05), which clearly implies that big flares are responsible for producing high speed CMEs and both parameters share a significant relationship . The source location of geoeffective halo CME events exhibit N-S asymmetry.

  9. Reading The Sun: A Three Dimensional Visual Model of The Solar Environment During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Carranza-fulmer, T. L.; Moldwin, M.

    2014-12-01

    The sun is a powerful force that has proven to our society that it has a large impact on our lives. Unfortunately, there is still a lack of awareness on how the sun is capable of affecting Earth. The over all idea of "Reading The Sun" installation is to help demonstrate how the sun impacts the Earth, by compiling various data sources from satellites (SOHO, SDO, and STERO) with solar and solar wind models (MAS and ENLIL) to create a comprehensive three dimensional display of the solar environment. It focuses on the current solar maximum of solar cycle 24 and a CME that impacted Earth's magnetic field on February 27, 2014, which triggered geomagnetic storms around the Earth's poles. The CME was an after-effect of a class X4.9 solar flare, which was released from the sun on February 25, 2014. "Reading The Sun" is a 48" x 48" x 48" hanging model of the sun with color coded open opposing magnetic field lines along with various layers of the solar atmosphere, the heliospheric current sheet, and the inner planets. At the center of the xyz axis is the sun with the open magnetic field lines and the heliospheric current sheet permeating inner planetary space. The xyz axes are color coded to represent various types of information with corresponding visual images for the viewer to be able to read the model. Along the z-axis are three colors (yellow, orange, and green) that represent the different layers of the solar atmosphere (photosphere, chromosphere, and corona) that correspond to three satellite images in various spectrums related to a CME and Solar Flare and the xy-plane shows where the inner planets are in relation to the sun. The exhibit in which "Reading The Sun "is being displayed is called, The Rotation of Language at the Wheather Again Gallery in Rockaway, New York. The intent of the exhibit is to both celebrate as well as present a cautionary tale on the ability of human language to spark and ignite the individual and collective imagination towards an experience

  10. Climate changes and solar cycles recorded at the Holocene Paraná Delta, and their impact on human population

    PubMed Central

    Milana, Juan Pablo; Kröhling, Daniela

    2015-01-01

    The Paraná delta, growing at a rate of c. 2 km2 yr−1 since 6,000 yrs, is one of the most complete records of the Late Holocene in southern South America. The evolution of this 17,400 km2 delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions. The Paraná delta shifted from fluvial, to wave-dominated, and back to the present fluvial-dominated delta, in response to climate changes associated with wind activity correlating with South American glacial cycles. The wave-dominated windy period coincides with the activation of the Pampean Sand Sea, suggesting desert conditions prevailed on the Pampas between 5,300 and 1,700 yrs, in coincidence with scarce or absent pre-historic aborigine remains (“archeological silence”). Further warmer and less windy conditions allowed human repopulation. Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution. An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region. PMID:26246410

  11. Climate changes and solar cycles recorded at the Holocene Paraná Delta, and their impact on human population

    NASA Astrophysics Data System (ADS)

    Milana, Juan Pablo; Kröhling, Daniela

    2015-08-01

    The Paraná delta, growing at a rate of c. 2 km2 yr-1 since 6,000 yrs, is one of the most complete records of the Late Holocene in southern South America. The evolution of this 17,400 km2 delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions. The Paraná delta shifted from fluvial, to wave-dominated, and back to the present fluvial-dominated delta, in response to climate changes associated with wind activity correlating with South American glacial cycles. The wave-dominated windy period coincides with the activation of the Pampean Sand Sea, suggesting desert conditions prevailed on the Pampas between 5,300 and 1,700 yrs, in coincidence with scarce or absent pre-historic aborigine remains (“archeological silence”). Further warmer and less windy conditions allowed human repopulation. Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution. An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

  12. Climate changes and solar cycles recorded at the Holocene Paraná Delta, and their impact on human population.

    PubMed

    Milana, Juan Pablo; Kröhling, Daniela

    2015-08-06

    The Paraná delta, growing at a rate of c. 2 km(2) yr(-1) since 6,000 yrs, is one of the most complete records of the Late Holocene in southern South America. The evolution of this 17,400 km(2) delta enclosed in Plata estuary, can be tracked by a series of 343 successive coastal-ridges showing a c.11 years period, in coincidence with sunspot cycle, also found in some North Hemisphere coastal-ridge successions. The Paraná delta shifted from fluvial, to wave-dominated, and back to the present fluvial-dominated delta, in response to climate changes associated with wind activity correlating with South American glacial cycles. The wave-dominated windy period coincides with the activation of the Pampean Sand Sea, suggesting desert conditions prevailed on the Pampas between 5,300 and 1,700 yrs, in coincidence with scarce or absent pre-historic aborigine remains ("archeological silence"). Further warmer and less windy conditions allowed human repopulation. Results suggest that aside the solar forcing, both short and medium term climate changes controlled delta evolution. An important learning is that a slight cooling would turn the highly productive pampas, into that unproductive desert and, given the lack of artificial irrigation systems, changing present-day warmhouse into a cooling cycle might be economically catastrophic for the region.

  13. Near-Earth Solar Wind Flows and Related Geomagnetic Activity During more than Four Solar Cycles (1963-2011)

    NASA Technical Reports Server (NTRS)

    Richardson, Ian G.; Cane, Hilary V.

    2012-01-01

    In past studies, we classified the near-Earth solar wind into three basic flow types based on inspection of solar wind plasma and magnetic field parameters in the OMNI database and additional data (e.g., geomagnetic indices, energetic particle, and cosmic ray observations). These flow types are: (1) High-speed streams associated with coronal holes at the Sun, (2) Slow, interstream solar wind, and (3) Transient flows originating with coronal mass ejections at the Sun, including interplanetary coronal mass ejections and the associated upstream shocks and post-shock regions. The solar wind classification in these previous studies commenced with observations in 1972. In the present study, as well as updating this classification to the end of 2011, we have extended the classification back to 1963, the beginning of near-Earth solar wind observations, thereby encompassing the complete solar cycles 20 to 23 and the ascending phase of cycle 24. We discuss the cycle-to-cycle variations in near-Earth solar wind structures and l1e related geomagnetic activity over more than four solar cycles, updating some of the results of our earlier studies.

  14. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. III. THE EFFECTS OF SOLAR ROTATION AND ACTIVITY CYCLE

    SciTech Connect

    Pogorelov, Nikolai V.; Borovikov, Sergey N.; Zank, Gary P.; Ogino, Tatsuki E-mail: snb0003@uah.edu E-mail: ogino@stelab.nagoya-u.ac.jp

    2009-05-10

    We investigate the effects of the 11 year solar cycle and 25 day rotation period of the Sun on the interaction of the solar wind (SW) with the local interstellar medium (LISM). Our models take into account the partially ionized character of the LISM and include momentum and energy transfer between the ionized and neutral components. We assume that the interstellar magnetic field vector belongs to the hydrogen deflection plane as discovered in the SOHO SWAN experiment. This plane is inclined at an angle of about 60 deg. toward the ecliptic plane of the Sun, as suggested in recent publications relating the local interstellar cloud properties to the radio emission observed by Voyager 1. It is assumed that the latitudinal extent of the boundary between the slow and fast SW regions, as well as the angle between the Sun's rotation and magnetic-dipole axes, are periodic functions of time, while the polarity of the interstellar magnetic field changes sign every 11 years at the solar maximum. The global variation of the SW-LISM interaction pattern, the excursions of the termination shock and the heliopause, and parameter distributions in certain directions are investigated. The analysis of the behavior of the wavy heliospheric current sheet in the supersonic SW region shows the importance of neutral atoms on its dynamics.

  15. A study of density modulation index in the inner heliospheric solar wind during solar cycle 23

    SciTech Connect

    Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K. E-mail: jerry@prl.res.in E-mail: p.subramanian@iiserpune.ac.in E-mail: tokumaru@stelab.nagoya-u.ac.jp

    2014-11-01

    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ε {sub N} ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ε {sub N} in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ΔN have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advanced Composition Explorer. Our analysis reveals that 0.001 ≲ ε {sub N} ≲ 0.02 and does not vary appreciably with heliocentric distance. We also find that ε {sub N} declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.

  16. Using dynamo theory to predict the sunspot number during solar cycle 21

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

    1978-01-01

    On physical grounds it is suggested that the polar field strength of the sun near a solar minimum is closely related to the solar activity of the following cycle. Four methods of estimating the polar magnetic field strength of the sun near solar minimum are employed to provide an estimate of the yearly mean sunspot number of cycle 21 at solar maximum of 140 + or - 20. This estimate may be considered a first-order attempt to predict the cycle activity using one parameter of physical importance based upon dynamo theory.

  17. Explaining solar cycle effects on composition as it relates to the winter anomaly

    NASA Astrophysics Data System (ADS)

    Burns, A. G.; Solomon, S. C.; Wang, W.; Qian, L.; Zhang, Y.; Paxton, L. J.; Yue, X.; Thayer, J. P.; Liu, H. L.

    2015-07-01

    The solar cycle variation of F2 region winter anomaly is related to solar cycle changes in the latitudinal winter-to-summer difference of O/N2. Here we use the National Center for Atmospheric Research-Global Mean Model to develop a concept of why the latitudinal winter-to-summer difference of O/N2 varies with solar cycle. The main driver for these seasonal changes in composition is vertical advection, which is expressed most simply in pressure coordinates. Meridional winds do not change over the solar cycle, so the vertical winds should also not change. The other component of vertical advection is the vertical gradient of composition. Is there any reason that this should change? At solar maximum vertical temperature gradients between 100 and 200 km altitude are strong, whereas they are weak at solar minimum. To maintain the same pressure, the weak vertical temperature gradients at solar minimum must be balanced by weak density gradients and the strong temperature gradients at solar maximum must be balanced by strong density gradients to obtain the same pressure profile. Changes in the vertical density gradients are species dependent: heavy species change more and light species change less than the average density change. Hence, vertical winds act on stronger O/N2 gradients at solar maximum than they do at solar minimum, and a stronger winter-to-summer difference of O/N2 occurs at solar maximum compared with solar minimum.

  18. The solar diameter is most probably constant over the solar cycle

    NASA Astrophysics Data System (ADS)

    Damé, Luc

    We analyzed 7 years of filtregrams data (150000 photograms and magnetograms) of the SOHO/MDI experiment. We used the maximum possible sampling compatible with full frame recording, carefully avoiding any suspicious filtregram. Going further than the previous analysis of Emilio et al. (Ap. J. 543, 2000) and Kuhn et al. (Ap. J. 613, 2004) we better corrected for changes in optical aberrations and, along Turmon et al. (Ap. J., 568, 396, 2002), we reduced radius measurement errors by identifying active regions from magnetograms and by avoiding radius measurements herein. We found that, within the limit of our noise level uncertainties (8 to 9 mas), the solar diameter is compatible with constancy over the half cycle investigated. Our results confirm the reanalysis of the 7 years of MDI data of Antia (Ap. J. 590, 2003), with a completely different method since using the ultra-precise frequency variation of the f-modes (fundamental modes linked to the diameter), who found (carefully removing the yearly Earth induced variations and avoiding the SOHO data gap of 1999) that the diameter is constant over the half solar cycle (radius variation are less than 0.6 km, 0.8 mas -nothing over noise level). We can conclude, along Antia, that: "If a careful analysis is performed, then it turns out that there is no evidence for any variation in the solar radius." There were no theoretical reasons for large solar radius variations and there is no observational evidence for them with consistent space observations made with 3 different approaches.

  19. Rotation of solar magnetic fields for the current solar cycle 24

    SciTech Connect

    Shi, X. J.; Xie, J. L.

    2014-11-01

    The rotation of solar magnetic fields for the current solar cycle 24 is investigated through a cross-correlation analysis of the Carrington synoptic maps of solar photospheric magnetic fields during Carrington rotation numbers 2076-2146 (2008 October to 2014 January). The sidereal rotation rates of positive and negative magnetic fields at some latitudes are shown, and it can be found that the positive (negative) fields generally rotate faster than the negative (positive) fields in the southern (northern) hemisphere at low latitudes. The mean rotation profiles of total, positive, and negative magnetic fields between ±60° latitudes in the time interval are also obtained. It should be noted that both of the mean rotation profiles of the positive and negative magnetic fields, as well as the mean rotation profile of the total magnetic field, exhibit a quasi-rigid rotation at latitudes above about 55°. The mean rotation rates of the positive (negative) polarity reach their maximum values at about 9°(6)° latitude in the southern (northern) hemisphere. The mean rotation profile of the total magnetic field displays an obvious north-south asymmetry, where the rotation seems to be more differential in the northern hemisphere. The latitude variation in the rotation rate differences between positive and negative magnetic fields is further studied, and it is found that magnetic fields with the same polarity as the leading sunspots at a given hemisphere rotate faster than those with the opposite polarity, except for the zones around 52° latitude of the southern hemisphere and around 35° latitude of the northern hemisphere. The implication of these results is discussed. It is clear that the obtained results can provide some observational constraints on the theoretical research of the mechanisms of differential rotation and solar cycle.

  20. Evolution of the 155 day periodicity in sunspot areas during solar cycles 12 to 21

    SciTech Connect

    Lean, J. )

    1990-11-01

    Sunspot area data during solar cycles 12-21 are examined with both periodogram and evolutionary spectral analysis techniques for evidence of a periodicity near 155 days. This periodicity is found to be present only during epochs of maxium activity, when it modulates the sunspot areas by as much as 15-20 percent of the amplitude of the 11 yr cycle. The 155 day periodicity typically occurs in episodes of from 1 to 3 yr, with sequential episodes often in opposite solar hemispheres; the strengths of these episodes appear to track the general level of solar activity. Comparing the phases of sinusoids fitted to the sunspot area data within individual solar cycles provides evidence for coherency within + or - 8 days of a period at 155 days between solar cycles 19, 20, and 21. However, within any one episode the actual period of the 155 day cycle may drift from 130 to 185 days. 31 refs.

  1. Prediction of the smoothed monthly mean sunspot numbers for solar cycle 24

    NASA Astrophysics Data System (ADS)

    Wang, Jialong; Miao, Juan; Liu, Siqing; Gong, Jiancun; Zhu, Cuilian

    2008-12-01

    The prediction for the smoothed monthly mean sunspot numbers (hereafter SMSNs) of solar cycle 23, which was given with a similar cycle method proposed by us at the beginning time of cycle 23, is analyzed and verified in this paper. Using our predicted maximum SMSN and the ascending length for solar cycle 24, and assuming their relative errors to be respectively 20% and ± 7 months, solar cycles 2, 4, 8, 11, 17, 20 and 23 are selected to be the similar cycles to cycle 24. The selected solar cycles are divided into two groups. The first group consists of all the selected cycles; while the second group consists of only cycles 11, 17, 20 and 23. Two SMSN time profiles then may be obtained, respectively, for the two similar cycle groups. No significant difference is found between the two predicted time profiles. Considering the latest observed sunspot number so far available for cycle 23 and the predictions for the minimum SMSN of cycle 24, a date calibration is done for the obtained time profiles, and thus, SMSNs for 127 months of cycle 24, from October 2007 to April 2018, are predicted.

  2. The representation of solar cycle signals in stratospheric ozone - Part 1: A comparison of recently updated satellite observations

    NASA Astrophysics Data System (ADS)

    Maycock, Amanda C.; Matthes, Katja; Tegtmeier, Susann; Thiéblemont, Rémi; Hood, Lon

    2016-08-01

    Changes in incoming solar ultraviolet radiation over the 11-year solar cycle affect stratospheric ozone abundances. It is important to quantify the magnitude, structure, and seasonality of the associated solar-ozone response (SOR) to understand the impact of the 11-year solar cycle on climate. Part 1 of this two-part study uses multiple linear regression analysis to extract the SOR in a number of recently updated satellite ozone datasets covering different periods within the epoch 1970 to 2013. The annual mean SOR in the updated version 7.0 (v7.0) Stratospheric Aerosol and Gas Experiment (SAGE) II number density dataset (1984-2004) is very consistent with that found in the previous v6.2. In contrast, we find a substantial decrease in the magnitude of the SOR in the tropical upper stratosphere in the SAGE II v7.0 mixing ratio dataset (˜ 1 %) compared to the v6.2 (˜ 4 %). This difference is shown to be largely attributable to the change in the independent stratospheric temperature dataset used to convert SAGE II ozone number densities to mixing ratios. Since these temperature records contain substantial uncertainties, we suggest that datasets based on SAGE II number densities are currently most reliable for evaluating the SOR. We further analyse three extended ozone datasets that combine SAGE II v7.0 number densities with more recent GOMOS (Global Ozone Monitoring by Occultation of Stars) or OSIRIS (Optical Spectrograph and Infrared Imager System) measurements. The extended SAGE-OSIRIS dataset (1984-2013) shows a smaller and less statistically significant SOR across much of the tropical upper stratosphere compared to the SAGE II data alone. In contrast, the two SAGE-GOMOS datasets (1984-2011) show SORs that are in closer agreement with the original SAGE II data and therefore appear to provide a more reliable estimate of the SOR. We also analyse the SOR in the recent Solar Backscatter Ultraviolet Instrument (SBUV) Merged Ozone Dataset (SBUVMOD) version 8.6 (VN8

  3. Distribution of the activity of the Sun during an average solar cycle

    NASA Astrophysics Data System (ADS)

    Svoreň, J.

    2015-12-01

    The paper offers a look at distribution of solar activity during an average solar cycle. Activity profiles in solar cycles from 13 to 17 and from 18 to 22 were studied based on the relative sunspot numbers. The average values for both groups of cycles were derived after the standardization to the maximum monthly value. Obtained values differed minimally, allowing us to derive a uniform distribution of activity for the entire review period from 1890 to 1996. The derived model of the distribution of activity in an average solar cycle allows us to predict the maximum value of an activity cycle with an advance of approximately 5 years based only on the value obtained in the first year of the cycle. This can be of use for, e.g., the planning of long-term human activities in outer space.

  4. Semi-annual Sq-variation in solar activity cycle

    NASA Astrophysics Data System (ADS)

    Pogrebnoy, V.; Malosiev, T.

    The peculiarities of semi-annual variation in solar activity cycle have been studied. The data from observatories having long observational series and located in different latitude zones were used. The following observatories were selected: Huancayo (magnetic equator), from 1922 to 1959; Apia (low latitudes), from 1912 to 1961; Moscow (middle latitudes), from 1947 to 1965. Based on the hourly values of H-components, the average monthly diurnal amplitudes (a difference between midday and midnight values), according to five international quiet days, were computed. Obtained results were compared with R (relative sunspot numbers) in the ranges of 0-30R, 40-100R, and 140-190R. It was shown, that the amplitude of semi-annual variation increases with R, from minimum to maximum values, on average by 45%. At equatorial Huancayo observatory, the semi-annual Sq(H)-variation appears especially clearly: its maximums take place at periods of equinoxes (March-April, September-October), and minimums -- at periods of solstices (June-July, December-January). At low (Apia observatory) and middle (Moscow observatory) latitudes, the character of semi-annual variation is somewhat different: it appears during the periods of equinoxes, but considerably less than at equator. Besides, with the growth of R, semi-annual variation appears against a background of annual variation, in the form of second peaks (maximum in June). At observatories located in low and middle latitudes, second peaks become more appreciable with an increase of R (March-April and September-October). During the periods of low solar activity, they are insignificant. This work has been carried out with the support from International Scientific and Technology Center (Project #KR-214).

  5. Helioseismic inferences of the solar cycles 23 and 24: GOLF and VIRGO observations

    NASA Astrophysics Data System (ADS)

    Salabert, D.; García, R. A.; Jiménez, A.

    2014-12-01

    The Sun-as-a star helioseismic spectrophotometer GOLF and photometer VIRGO instruments onboard the SoHO spacecraft are collecting high-quality, continuous data since April 1996. We analyze here these unique datasets in order to investigate the peculiar and weak on-going solar cycle 24. As this cycle 24 is reaching its maximum, we compare its rising phase with the rising phase of the previous solar cycle 23.

  6. Periodogram analysis of sunspot numbers and the relation with solar activities

    NASA Technical Reports Server (NTRS)

    Hady, Ahmed A.

    1995-01-01

    The time series of average monthly sunspot numbers during 1900-1992 is studied by using power spectral analysis. This prediction method is used to study the sunspot periodicities relations between its, and with the other periodicities by solar activities. There are periodicities (between few days and 5 years) overwhelm on the mean solar cycle. ( 11 year cycle). These periodicities have the same relation with variations of solar constant and solar radiation reaching the Earth's atmosphere in the last solar cycle. These periods are related to the solar magnetic activity and to the modulation of solar features due to solar rotation.

  7. Probing the equinoctial hypothesis over recent solar cycles

    NASA Astrophysics Data System (ADS)

    Farrugia, C.; Miyoshi, Y.; Jordanova, V.

    2003-04-01

    According to Russell and McPherron (1973), stronger and more frequent storms are induced on a half-annual cadence due to the tilt of the Earth's dipole. We carry out a statistical investigation of this using 1-hour averaged Dst index values as a measure of the strength of geomagnetic storms over the period 1969-2001 (3 solar cycles), and energetic electron and proton fluxes measured BY NOAA/TIROS typical of the inner ring current and radiation belts, respectively for the last 2 cycles in the interval 1979-2001. We subdivide the data sets into ascending (sunpsot number > 50) and descending phases (< 50 ), and the storm strengths into two categories: peak hourly Dst < -60 nT, and hourly peak Dst < -100 nT. The variation equinox / solstice is evident in both Dst measurments and energetic particles fluxes. The number of storms falls off exponentially with storm strength both at equinox and solstice. There is practically no difference in the average storm strength at equinox/solstice. However, the storm frequency of both categories is larger at equinox. Exceptional cases like the Bastille day (July 2000) form a large-scale deviation from this pattern. The aim of this study is to understand the effects of the orientation of the Earth's dipole on geomagnetic strom dynamics and to reveal systematics which will be useful for the development of space weather predictions. C. T. Russell and R. L. MCPherron, JGR, 78, 92, 1973 Work supported in part by NASA GRANT NAG 5-10883.

  8. SOLAR CYCLE PROPAGATION, MEMORY, AND PREDICTION: INSIGHTS FROM A CENTURY OF MAGNETIC PROXIES

    SciTech Connect

    Munoz-Jaramillo, Andres; DeLuca, Edward E.; Dasi-Espuig, Maria; Balmaceda, Laura A. E-mail: edeluca@cfa.harvard.edu E-mail: lbalmaceda@icate-conicet.gob.ar

    2013-04-20

    The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the lifetime of space-based assets and can create hazards to astronauts in space. In recent years there has been an effort to develop accurate solar cycle predictions (with aims at predicting the long-term evolution of space weather), leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. A major contributor to the disagreement is the lack of direct long-term databases covering different components of the solar magnetic field (toroidal versus poloidal). Here, we use sunspot area and polar faculae measurements spanning a full century (as our toroidal and poloidal field proxies) to study solar cycle propagation, memory, and prediction. Our results substantiate predictions based on the polar magnetic fields, whereas we find sunspot area to be uncorrelated with cycle amplitude unless multiplied by area-weighted average tilt. This suggests that the joint assimilation of tilt and sunspot area is a better choice (with aims to cycle prediction) than sunspot area alone, and adds to the evidence in favor of active region emergence and decay as the main mechanism of poloidal field generation (i.e., the Babcock-Leighton mechanism). Finally, by looking at the correlation between our poloidal and toroidal proxies across multiple cycles, we find solar cycle memory to be limited to only one cycle.

  9. Hard X-Ray Emission from Partially Occulted Solar Flares: RHESSI Observations in Two Solar Cycles

    NASA Astrophysics Data System (ADS)

    Effenberger, Frederic; Rubio da Costa, Fatima; Oka, Mitsuo; Saint-Hilaire, Pascal; Liu, Wei; Petrosian, Vahé; Glesener, Lindsay; Krucker, Säm

    2017-02-01

    Flares close to the solar limb, where the footpoints are occulted, can reveal the spectrum and structure of the coronal looptop source in X-rays. We aim at studying the properties of the corresponding energetic electrons near their acceleration site, without footpoint contamination. To this end, a statistical study of partially occulted flares observed with Reuven Ramaty High-Energy Solar Spectroscopic Imager is presented here, covering a large part of solar cycles 23 and 24. We perform detailed spectra, imaging, and light curve analyses for 116 flares and include contextual observations from SDO and STEREO when available, providing further insights into flare emission that were previously not accessible. We find that most spectra are fitted well with a thermal component plus a broken power-law, non-thermal component. A thin-target kappa distribution model gives satisfactory fits after the addition of a thermal component. X-ray imaging reveals small spatial separation between the thermal and non-thermal components, except for a few flares with a richer coronal source structure. A comprehensive light curve analysis shows a very good correlation between the derivative of the soft X-ray flux (from GOES) and the hard X-rays for a substantial number of flares, indicative of the Neupert effect. The results confirm that non-thermal particles are accelerated in the corona and estimated timescales support the validity of a thin-target scenario with similar magnitudes of thermal and non-thermal energy fluxes.

  10. GLE and the NON-GLE Solar Events Observed by AMS-02 in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Bindi, V.; Consolandi, C.; Corti, C.; Whitman, K.

    2014-12-01

    The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle detector installed on the International Space Station (ISS) on May 2011 to study origin and nature of cosmic rays in the energy range from hundreds of MeV to a few TeV. In the first 3 years of operation, AMS-02 measured the highest part of the Solar Energetic Particle (SEP) spectra produced during M-and X-class flares and fast Coronal Mass Ejection. AMS-02 is able to perform precise measurements in a short period of time which is typical of these transient phenomena and to collected enough statistics to fully measure fine structures and time evolution of the spectrum. So far in Solar Cycle 24, one official Ground Level Enhancement (GLE) was observed on May 17, 2012 by Neutron Monitors (NM) while another possible GLE on January 6, 2014 was detected by South Pole NM. Observations by GOES-13, in the high energy proton channels, suggest that there were only 5 SEP events with energies above 500 MeV in this Cycle 24. AMS-02 observations, instead, indicate that since May 2011 there were more than 5 solar events with energies above 500 MeV at Earth. AMS-02 observations, with unprecedented resolution, large acceptance and high statistics, can therefore help the heliophysics community to better understand the true behavior of SEPs at high energies and to constrain models of SEP production. The SEP fluxes of GLE and NON-GLE events observed by AMS-02 will be presented.

  11. Solar-cycle variation of the rotational shear near the solar surface

    NASA Astrophysics Data System (ADS)

    Barekat, A.; Schou, J.; Gizon, L.

    2016-10-01

    Context. Helioseismology has revealed that the angular velocity of the Sun increases with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the logarithmic radial gradient (dlnΩ/dlnr) in the upper 10 Mm is close to -1 from the equator to 60° latitude. Aims: We aim to measure the temporal variation of the rotational shear over solar cycle 23 and the rising phase of cycle 24 (1996-2015). Methods: We used f mode frequency splitting data spanning 1996 to 2011 from the Michelson Doppler Imager (MDI) and 2010 to 2015 from the Helioseismic Magnetic Imager (HMI). In a first for such studies, the f mode frequency splitting data were obtained from 360-day time series. We used the same method as in our previous work for measuring dlnΩ/dlnr from the equator to 80° latitude in the outer 13 Mm of the Sun. Then, we calculated the variation of the gradient at annual cadence relative to the average over 1996 to 2015. Results: We found the rotational shear at low latitudes (0° to 30°) to vary in-phase with the solar activity, varying by ~± 10% over the period 1996 to 2015. At high latitudes (60° to 80°), we found rotational shear to vary in anti-phase with the solar activity. By comparing the radial gradient obtained from the splittings of the 360-day and the corresponding 72-day time series of HMI and MDI data, we suggest that the splittings obtained from the 72-day HMI time series suffer from systematic errors. Conclusions: We provide a quantitative measurement of the temporal variation of the outer part of the near surface shear layer which may provide useful constraints on dynamo models and differential rotation theory.

  12. Concept definition study of small Brayton cycle engines for dispersed solar electric power systems

    NASA Technical Reports Server (NTRS)

    Six, L. D.; Ashe, T. L.; Dobler, F. X.; Elkins, R. T.

    1980-01-01

    Three first-generation Brayton cycle engine types were studied for solar application: a near-term open cycle (configuration A), a near-term closed cycle (configuration B), and a longer-term open cycle (configuration C). A parametric performance analysis was carried out to select engine designs for the three configurations. The interface requirements for the Brayton cycle engine/generator and solar receivers were determined. A technology assessment was then carried out to define production costs, durability, and growth potential for the selected engine types.

  13. A new solar cycle model including meridional circulation

    NASA Technical Reports Server (NTRS)

    Wang, Y.-M.; Sheeley, N. R., Jr.; Nash, A. G.

    1991-01-01

    A kinematic model is presented for the solar cycle which includes not only the transport of magnetic flux by supergranular diffusion and a poleward bulk flow at the sun's surface, but also the effects of turbulent diffusion and an equatorward 'return flow' beneath the surface. As in the earlier models of Babcock and Leighton, the rotational shearing of a subsurface poloidal field generates toroidal flux that erupts at the surface in the form of bipolar magnetic regions. However, such eruptions do not result in any net loss of toroidal flux from the sun (as assumed by Babcock and Leighton); instead, the large-scale toroidal field is destroyed both by 'unwinding' as the local poloidal field reverses its polarity, and by diffusion as the toroidal flux is transported equatorward by the subsurface flow and merged with its opposite hemisphere counterpart. The inclusion of meridional circulation allows stable oscillations of the magnetic field, accompanied by the equatorward progression of flux eruptions, to be achieved even in the absence of a radial gradient in the angular velocity. An illustrative case in which a subsurface flow speed of order 1 m/s and subsurface diffusion rate of order 10 sq km/s yield 22-yr oscillations in qualitative agreement with observations.

  14. QBO as Potential Amplifier of Solar Cycle Influence

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mangel, John G.; Wolff, Charles L.; Porter, Hayden S.

    2006-01-01

    The solar cycle (SC) effect in the lower atmosphere has been linked observationally to the quasi-biennial oscillation (QBO) of the zonal circulation. Salby and Callaghan (2000) in particular analyzed the QBO covering more than 40 years and found that it contains a large SC signature at 20 km. We discuss a 3D study in which we simulate the QBO under the influence of the SC. For a SC period of 10 years, the relative amplitude of radiative forcing is taken to vary with height: 0.2% (surface), 2% (50 km), 20% (100 km and above). This model produces in the lower stratosphere a relatively large modulation of the QBO, which appears to come from the SC and qualitatively agrees with the observations. The modulation of the QBO, with constant phase relative to the SC, is shown to persist at least for 50 years, and it is induced by a SC modulated annual oscillation that is hemispherically symmetric and confined to low latitudes.

  15. Temporal Offsets Between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators During Solar Cycle 23 and the Ascending Phase of Cycle 24

    NASA Astrophysics Data System (ADS)

    Özgüç, A.; Kilcik, A.; Georgieva, K.; Kirov, B.

    2016-05-01

    On the basis of a morphological analysis of yearly values of the maximum coronal mass ejection (CME) speed index, the sunspot number and total sunspot area, sunspot magnetic field, and solar flare index, the solar wind speed and interplanetary magnetic field strength, and the geomagnetic Ap and D_{st} indices, we point out the particularities of solar and geomagnetic activity during the last Cycle 23, the long minimum that followed it, and the ascending branch of Cycle 24. We also analyze the temporal offset between the maximum CME speed index and the above-mentioned solar, geomagnetic, and interplanetary indices. It is found that this solar activity index, analyzed jointly with other solar activity, interplanetary parameters, and geomagnetic activity indices, shows a hysteresis phenomenon. It is observed that these parameters follow different paths for the ascending and descending phases of Cycle 23. The hysteresis phenomenon represents a clue in the search for physical processes responsible for linking the solar activity to near-Earth and geomagnetic responses.

  16. Influence of the solar UV-radiation intensity on the 630-nm nightglow emission in the 23rd solar cycle

    NASA Astrophysics Data System (ADS)

    Ievenko, I. B.; Alekseev, V. N.; Parnikov, S. G.

    2011-10-01

    It is well known that the 630-nm nightglow emission intensity in midlatitudes increases by more than a factor of 2 during a sunspot maximum. It has been assumed that the phenomenon is caused by variations in solar UV radiation during a solar cycle (Fishkova, 1983). We present the results of photometric measurements of the nightglow 630.0 nm emission intensity at a latitude of 63° E and longitude of 130° E (Yakutsk) in 1990-2007. The dependence of the 630-nm emission intensity on solar activity on magnetically quiet days in the 22nd and 23rd solar cycles is shown. The close relationship between the 630-nm nightglow intensity and the intensity of extreme UV (EUV) with a correlation coefficient of 0.8-0.9 in 1997-2007 is ascertained from the SOHO/SEM data. The dominance of solar EUV in the excitation of nightglow 630-nm emission has thus been experimentally proved.

  17. Supercritical CO2 Power Cycles: Design Considerations for Concentrating Solar Power

    SciTech Connect

    Neises, Ty; Turchi, Craig

    2014-09-01

    A comparison of three supercritical CO2 Brayton cycles: the simple cycle, recompression cycle and partial-cooling cycle indicates the partial-cooling cycle is favored for use in concentrating solar power (CSP) systems. Although it displays slightly lower cycle efficiency versus the recompression cycle, the partial-cooling cycle is estimated to have lower total recuperator size, as well as a lower maximum s-CO2 temperature in the high-temperature recuperator. Both of these effects reduce recuperator cost. Furthermore, the partial-cooling cycle provides a larger temperature differential across the turbine, which translates into a smaller, more cost-effective thermal energy storage system. The temperature drop across the turbine (and by extension, across a thermal storage system) for the partial-cooling cycle is estimated to be 23% to 35% larger compared to the recompression cycle of equal recuperator conductance between 5 and 15 MW/K. This reduces the size and cost of the thermal storage system. Simulations by NREL and Abengoa Solar indicate the partial-cooling cycle results in a lower LCOE compared with the recompression cycle, despite the former's slightly lower cycle efficiency. Advantages of the recompression cycle include higher thermal efficiency and potential for a smaller precooler. The overall impact favors the use of a partial-cooling cycle for CSP compared to the more commonly analyzed recompression cycle.

  18. Flexible thermal cycle test equipment for concentrator solar cells

    DOEpatents

    Hebert, Peter H [Glendale, CA; Brandt, Randolph J [Palmdale, CA

    2012-06-19

    A system and method for performing thermal stress testing of photovoltaic solar cells is presented. The system and method allows rapid testing of photovoltaic solar cells under controllable thermal conditions. The system and method presents a means of rapidly applying thermal stresses to one or more photovoltaic solar cells in a consistent and repeatable manner.

  19. Evolution of the Interplanetary Magnetic Field sector structure during the last 15 solar cycles

    NASA Astrophysics Data System (ADS)

    Vokhmyanin, Mikhail

    We have inferred for the first time Interplanetary Magnetic Field (IMF) polarities from ground-based geomagnetic observations back to 1844. Reconstructions are reliable enough to study sector structure of the IMF in the past. The inferred daily polarities demonstrate solar-cycle changes during the nineteenth and twentieth centuries. We have analyzed statistics of the sector boundaries and found recurrences that reflect evolution of the solar wind sources. Additionally, seasonal variations of the ratio of positive and negative sectors provide evidence of solar magnetic field reversals during the last 15 solar cycles.

  20. Effects of Space Weather on Biomedical Parameters during the Solar Activity Cycles 23-24.

    PubMed

    Ragul'skaya, M V; Rudenchik, E A; Chibisov, S M; Gromozova, E N

    2015-06-01

    The results of long-term (1998-2012) biomedical monitoring of the biotropic effects of space weather are discussed. A drastic change in statistical distribution parameters in the middle of 2005 was revealed that did not conform to usual sinusoidal distribution of the biomedical data reflecting changes in the number of solar spots over a solar activity cycle. The dynamics of space weather of 2001-2012 is analyzed. The authors hypothesize that the actual change in statistical distributions corresponds to the adaptation reaction of the biosphere to nonstandard geophysical characteristics of the 24th solar activity cycle and the probable long-term decrease in solar activity up to 2067.

  1. Effects of long-period solar activity fluctuation on temperature and pressure of the terrestrial atmosphere

    NASA Technical Reports Server (NTRS)

    Rubashev, B. M.

    1978-01-01

    The present state of research on the influence of solar sunspot activity on tropospheric temperature and pressure is reviewed. The existence of an 11-year temperature cycle of 5 different types is affirmed. A cyclic change in atmospheric pressure, deducing characteristic changes between 11-year cycles is discussed. The existence of 80-year and 5-to-6-year cycles of temperature is established, and physical causes for birth are suggested.

  2. A comparative study of solar facula during cycle 23 and 24

    NASA Astrophysics Data System (ADS)

    Chowdhury, P.; Choudhary, D. P.; Moon, Y. J.

    2015-12-01

    The solar activity minimum between the end of cycle 23 and beginning of cycle 24 was the longest and deepest since the modern satellite era of 20th century. In this paper, we have investigated statistical properties of solar facula and sunspot area (and their ratio) covering entire solar cycle 23 and the ascending phase of cycle 24. The facular area has been considered from the K-line composite at the San Fernando Observatory and is a direct measurement of the strength of solar cycle activity. It is found that solar facular area decreased during minimum phase of cycle 23/24 compared to maximum phase and also during rising phase of cycle 24. However, the ratio of facula to sunspot area increased during minimum epoch of cycle 23. Power spectrum analysis shows that along with other periods, the solar rotational periods 22 -31 days and Rieger type periods are both prominent during maxima, minima of cycle 23 and ascending branch of cycle 24. During the decline phase of cycle 23, the period ~ 27 days is more prominent whereas ~ 14 days and ~ 31 days periods are dominant during activity maxima. During maximum phase of cycle 23 and 24, there was no phase lag between sunspot and facular area, but a phase lag ~ 3 months has been detected during activity minima of cycle 23. These results indicate that the distribution of active regions during the activity maximum years is quite different from that in the minimum years. We shall present discussion of our results in this paper.

  3. The Divergence of CME and Sunspot Number Rates During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Webb, David F.; St. Cyr, Orville Chris; Xie, Hong; Kuchar, Thomas Andrew

    2014-06-01

    In the previous three solar cycles the frequency of occurrence of CMEs observed in white light has closely tracked the solar cycle in both phase and amplitude, varying by an order of magnitude over the cycle. LASCO has now observed the entire solar Cycle 23 and continues to observe through the current rise and maximum phases of Cycle 24. Cycle 23 had an unusually long decline and extended minimum. During this period we have been able to image and count CMEs in the heliosphere, and can determine rates from both LASCO and STEREO SECCHI (since 2007) coronagraphs and from the Solar Mass Ejection Imager (SMEI - since 2003) and the SECCHI Heliospheric Imagers in the heliosphere. Manual rates estimated by observers are now supplemented by counts from identifications made by automatic programs, such as contained in the SEEDS, CACTus and ARTEMIS catalogs. Since the cycle 23/24 minimum, the CME and sunspot number rates have diverged, with similar cycle 23/24 rise and peak CME rates but much lower SSN rates in this cycle. We will discuss these rate estimates and their implications for the evolution of the global solar magnetic field.

  4. Solar cycle variations in ion composition in the dayside ionosphere of Titan

    NASA Astrophysics Data System (ADS)

    Madanian, H.; Cravens, T. E.; Richard, M. S.; Waite, J. H.; Edberg, N. J. T.; Westlake, J. H.; Wahlund, J.-E.

    2016-08-01

    One Titanian year spans over two complete solar cycles, and the solar irradiance has a significant effect on ionospheric densities. Solar cycle 24 has been one of the quietest cycles on record. In this paper we show data from the Cassini ion and neutral mass spectrometer (INMS) and the radio and plasma wave science Langmuir probe spanning the time period from early 2005, at the declining phase of solar cycle 23, to late 2015 at the declining phase of solar cycle 24. Densities of different ion species measured by the INMS show a consistent enhancement for high solar activity, particularly near the ionospheric peak. The density enhancement is best seen in primary ion species such as CH3+ rather than heavier ion species such as HCNH+. Unlike at Earth, where the ionosphere and atmosphere thermally expand at high solar activity, at Titan the altitude of the ionospheric peak decreases, indicating that the underlying neutral atmosphere was less extensive. Among the major ion species, CH5+ shows the largest decrease in peak altitude, whereas heavy ions such as C3H5+ show very little decrease. We also calculate the ion production rates using a theoretical model and a simple empirical model using INMS data and show that these effectively predict the increased ion production rates at high solar activity.

  5. Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24

    NASA Technical Reports Server (NTRS)

    Karna, N.; Webber, S.A. Hess; Pesnell, W.D.

    2014-01-01

    An analysis of solar polar coronal hole (PCH) areas since the launch of the Solar Dynamics Observatory (SDO) shows how the polar regions have evolved during Solar Cycle 24. We present PCH areas from mid-2010 through 2013 using data from the Atmospheric Imager Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard SDO. Our analysis shows that both the northern and southern PCH areas have decreased significantly in size since 2010. Linear fits to the areas derived from the magnetic-field properties indicate that, although the northern hemisphere went through polar-field reversal and reached solar-maximum conditions in mid-2012, the southern hemisphere had not reached solar-maximum conditions in the polar regions by the end of 2013. Our results show that solar-maximum conditions in each hemisphere, as measured by the area of the polar coronal holes and polar magnetic field, will be offset in time.

  6. Solar cycle variation of interplanetary disturbances observed as Doppler scintillation transients

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

    Interplanetary disturbances characterized by plasma that is more turbulence and/or moves faster than the background solar wind are readily defected as transients in Doppler scintillation measurements of the near-Sun solar wind. Systematic analysis of over 23,000 hours of Pioneer Venus Orbiter Doppler measurements obtained inside 0.5 AU during 1979-1987 have made it possible for the first time to investigate the frequency of occurrence of Doppler scintillation transients under solar minimum conditions and to determine its dependence on solar cycle. On the basis of a total of 142 transients, Doppler scintillation transient rates vary from a high of 0.22 in 1979 (one every 4.6 days) to a low of 0.077 transients/d in 1986 (one every 13 days), a decrease by almost a factor of 3 from solar maximum to solar minimum. This solar cycle variation, the strongest yet of any solar wind Doppler scintillation property, is highly correlated with both solar activity characterized by sunspot number and the coronal mass ejection rates deduced from Solswind and Solar Maximum Mission (SMM) coronagraph observations. These results indicate that coronal mass ejections and Doppler scintillation transients are closely related not just during solar maximum, as occasional individual comparisons have shown in the past, but throughout the entire solar cycle, and strengthen the notation that the Doppler scintillation and optical transients are different manifestations of the same physical phenomenon. The magnitudes of the transients, as described by the ratio of peak to pretransient scintillation levels (EF for enhancement factor), and their distribution iwth heliocentric distance also vary with solar cycle. While EF tends to diminish with increasing heliocentric distance during high solar activity, it is more evenly distributed during low solar activity. EF is also lower during solar minimum, as 13% of the transients during solar maximum have values exceeding 23, the highest EF observed during

  7. Periodicities of hard x-ray burst during the last solar cycle

    NASA Technical Reports Server (NTRS)

    Hady, Ahmed A.

    1995-01-01

    By using power spectrum and standard FFT time series analysis, the Hard X-ray burst during solar cycle -22 were studied. This data of Hard X-ray burst spectrometer (HXRBS) on the solar maximum mission from Launch and February 14, 1980, through re-entry on December 2, 1989, by NASA artificial satellite. The results indicate that there are short and intermediate solar periodicities. Also it is found that there is a relation between the short periodicities (few minutes) with similar periodicities in solar radio emissions and in good agreement with the theoretical mode of solar oscillations.

  8. An extension of the VIRA electron temperature and density models to include solar cycle variations

    NASA Astrophysics Data System (ADS)

    Brace, L. H.; Theis, R. F.

    The original VIRA ionosphere model was based primarily on the Pioneer Venus Orbiter (PVO) data obtained at solar maximum (F10.7~200) in 1979 and 1980 when periapsis was being maintained deep in the Venusian ionosphere. In situ measurements provided data on temperature, composition, density, and drift velocity, while the radio occultation method provided height profiles of electron density, N_e. The solar cycle variation was deduced by comparison with the Venera 9 and 10 occultation data from the previous solar minimum. No data were available on the solar cycle variations of other ionospheric parameters, because periapsis had already risen out of the ionosphere by the time solar activity began to decline early in 1983. During the Entry period in the Fall of 1992, however, PVO got a brief glimpse of the nightside ionosphere at lower solar activity (F10.7~120). During the intervening decade important in situ data were obtained on the upper nightside ionosphere that extends far down stream from the planet. This region was found to be highly sensitive to solar wind interactions and solar activity. In this paper, we discuss ways in which the later PVO data can be used to extend the VIRA model to higher altitudes and to include the solar cycle variations. As an example, we present some pre-entry Orbiter Electron Temperature Probe measurements that provide new clues as to the dayside T_e behavior at low solar activity.

  9. An analysis of solar-cycle temporal relationships among activity indicators

    NASA Astrophysics Data System (ADS)

    Bachmann, K. T.; Maymani, H.; Nautiyal, K.; te Velde, V.

    2004-01-01

    Differences in the time development of solar activity indices are an important clue in the search for physical processes responsible for changing solar emission at various wavelengths. In this paper we describe our investigation of temporal relationships among two space-based indices, Lyman-α 121.6 nm emission (Lα) and the Mg II 280 nm core-to-wing ratio, and four ground-based indices - the 10.7 cm flux (F10), the He I 1083 nm equivalent width, the Ca II K 393.4 nm emission index, and the International Sunspot Number (ISN). We provide scatterplots of index pairs passed through a 2-year Gaussian filter during each available solar cycle, and we approximate the temporal relationships quantitatively as overall temporal offsets with uncertainties. We reconcile our findings with qualitative ideas concerning the variation of solar emissions with solar activity. Since the F10 and ISN time series are longer than four complete solar cycles, we are able to evaluate the reproducibility of temporal offsets over multiple solar cycles. The chief motivation for our work is to improve solar indicator analysis by providing a method of seeing and analyzing temporal relationships clearly and easily. We believe that future physical models of magnetic activity and spectral emissions in the solar chromosphere and transition region may make quantitative predictions of temporal relationships among full-disk solar indices for comparison with analyses such as ours.

  10. Periodic (18.6-year) and cyclic (11-year) induced drought and flood in western North America

    NASA Astrophysics Data System (ADS)

    Currie, Robert Guinn

    1984-08-01

    Analysis of 102 reent tree-ring chronologies confirms earlier evidence for 18.6-year tidal drought/flood induction (Currie, 1981d, 1984b) and led to discovery of 11-year solar cycle induced drought/flood for western North America. Bistable phasing in terms of geography is found with epohs of maximum in lunar nodal 18.6-year drought in western Canada out of phase with those in the western United States and northern Mexico the past two centuries. Solar drought/flood induction provides one mechanism that appears to have modulated the intensity of nodal drought/flood induction in the latter region, most recently at epoch 1936.1. The above results were confirmed by analysis of yet more voluminous data, and they le to discovery of an example of bistable phasing with respect to time in western Canada during the 17th century. The implications for agriculture of such phenomena, which occur worldwide (Currie, 1984c), are surveyed.

  11. 3D Solar Wind Structure Features Characterizing the Rise of Cycle 24

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ellenburg, M. A.; Riley, P.; Lee, C. O.; Arge, C. N.; Jian, L.; Russell, C. T.; Simunac, K.; Galvin, A. B.; Petrie, G. J.

    2011-12-01

    Since the launch of the STEREO mission in 2006, there has been renewed interest in the 3D structure of the solar wind, spurred in part by the unusual cycle 23 solar minimum and current solar cycle rise. Of particular significance for this subject has been the ubiquitous occurrence of low latitude coronal holes and coronal pseudo-streamers. These coupled features have been common both because of the relative strength of high order spherical harmonic content of the global coronal field, and the weakness of the field compared to the previous two well-observed cycles. We consider the effects of the low latitude coronal holes and pseudo-streamers on the near-ecliptic solar wind and interplanetary field. In particular, we illustrate how the now common passage of streams with low latitude sources and pseudo-streamer boundaries is changing our traditional perceptions of local solar wind structures.

  12. Periodic 18.6-year and cyclic 11-year induced drought and flood in northeastern China and some global implications

    NASA Astrophysics Data System (ADS)

    Currie, Robert Guinn; Fairbridge, Rhodes W.

    The general patterns of climatic evolution in China during the Holocene are reviewed, and following the postglacial eustatic rise of sea-level and the institution of the East Asian Monsoon, the systems and principal fluctuations are found to be concordant with those operating elsewhere in the globe. China's unique wealth of written history provides an abundance of proxy data on the climatic record and that record now furnishes a basis for analysing both long-term and short-term fluctuations, as well as sunspot behavior, that together provide an insight into extraterrestrial forcing. Recent Chinese work suggests a solar forcing, but our own studies suggest rather that a lunar tidal component, reinforced at times by the solar element may prove more important. Analysis of a drought-flood index for Peking (Beijing) in northeastern China since A.D. 1470 supports evidence (Hameed et al., 1983) for both periodic lunar nodal 18.6-year and solar cyclic 11-year induced drought-flood in the region. The nodal term exhibits bistable phasing with respect to epochs of tidal maxima (for our century epochs occurred at 1917.5, 1936.1, 1954.7 and 1973.3), a phenomenon previously found in drought-flood proxy data for South America (Currie, 1983), India (Currie, 1984a), North America (Currie, 1984d), and Africa (Hameed and Currie, 1985; Currie and Hameed, 1985). Solar cycle epochs of drought-flood are tabulated for the past two centuries, and compared with those from North America and Africa.

  13. The Variability of Solar Spectral Irradiance and Solar Surface Indices Through the Solar Activity Cycles 21-23

    NASA Astrophysics Data System (ADS)

    Deniz Goker, Umit

    2016-07-01

    A study of variations of solar spectral irradiance (SSI) in the wavelength ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We developed a special software for extracting the data and reduced this data by using the MATLAB. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) emission lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar cycles (SCs) 23 and 24. We also compared our results with the ground-based telescopes as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal Data (KKL) and NGDC Homepage (Rome and Learmonth Solar Observatories). We studied the variations of total solar irradiance (TSI), magnetic field, sunspots/sunspot groups, Ca II K-flux, faculae and plage areas data with these ground-based telescopes, respectively. We reduced the selected data using the Phyton programming language and plot with the IDL programme. Therefore, we found that there was a decrease in the area of bright faculae and chromospheric plages while the percentage of dark faculae and plage decrease, as well. However, these decreases mainly occurred in small sunspots, contrary to this, these terms in large sunspot groups were comparable to previous SCs or even larger. Nevertheless, negative correlations between ISSN and SSI data indicate that these emissions are in close connection with the classes of sunspots/sunspot groups and "PLAGE" regions. Finally, we applied the time series of the chemical elements correspond to the wavelengths 121.5 nm-300.5 nm and compared with the ISSN data. We found an unexpected increasing in the 298.5 nm for the Fe II element. The variability of Fe II (298.5 nm) is in close connection with the plage regions and the sizes of the

  14. On the Influence of the Solar Bi-Cycle on Comic Ray Modulatio

    NASA Astrophysics Data System (ADS)

    Lifter, N. Part Xxvii: A. Defect Of The Solar Dynamo. B.; Scissors, K.; Sprucener, H.

    In this presentation we propose a new paradigm that explains the different lengths of individual solar Hale cycles. It proves beneficial to distinguish between a so-called inHale and ex-Hale cycle, which together form the solar bi-cycle. We carefully analyzed the influence of so-called complex mode excitations (CMEs) on comic ray modulation, in particular on the drifts of the comic isotope O+3 , which we found to induce characteristic anisotropies. This comic isotope anisotropy (CIA) is caused by the wellknown north-south asymmetry (NSA) and can be observed as a rare Forbush increase (FBI). The latter is linked to the solar magnetic field which appears to have a chaotic behaviour (for details see part I-XXVI). Especially during an ex-Hale cycle magnetic flux is pseudo-pneumatically escaping through a coronal hole. Consequently, the solar dynamo can no longer operate efficiently, i.e. is defect.

  15. Long-Range Solar Activity Predictions: A Reprieve from Cycle #24's Activity

    NASA Technical Reports Server (NTRS)

    Richon, K.; Schatten, K.

    2003-01-01

    We discuss the field of long-range solar activity predictions and provide an outlook into future solar activity. Orbital predictions for satellites in Low Earth Orbit (LEO) depend strongly on exospheric densities. Solar activity forecasting is important in this regard, as the solar ultra-violet (UV) and extreme ultraviolet (EUV) radiations inflate the upper atmospheric layers of the Earth, forming the exosphere in which satellites orbit. Rather than concentrate on statistical, or numerical methods, we utilize a class of techniques (precursor methods) which is founded in physical theory. The geomagnetic precursor method was originally developed by the Russian geophysicist, Ohl, using geomagnetic observations to predict future solar activity. It was later extended to solar observations, and placed within the context of physical theory, namely the workings of the Sun s Babcock dynamo. We later expanded the prediction methods with a SOlar Dynamo Amplitude (SODA) index. The SODA index is a measure of the buried solar magnetic flux, using toroidal and poloidal field components. It allows one to predict future solar activity during any phase of the solar cycle, whereas previously, one was restricted to making predictions only at solar minimum. We are encouraged that solar cycle #23's behavior fell closely along our predicted curve, peaking near 192, comparable to the Schatten, Myers and Sofia (1996) forecast of 182+/-30. Cycle #23 extends from 1996 through approximately 2006 or 2007, with cycle #24 starting thereafter. We discuss the current forecast of solar cycle #24, (2006-2016), with a predicted smoothed F10.7 radio flux of 142+/-28 (1-sigma errors). This, we believe, represents a reprieve, in terms of reduced fuel costs, etc., for new satellites to be launched or old satellites (requiring reboosting) which have been placed in LEO. By monitoring the Sun s most deeply rooted magnetic fields; long-range solar activity can be predicted. Although a degree of uncertainty

  16. The dependence of the [FUV-MUV] colour on solar cycle

    NASA Astrophysics Data System (ADS)

    Lovric, Mija; Tosone, Federico; Pietropaolo, Ermanno; Del Moro, Dario; Giovannelli, Luca; Cagnazzo, Chiara; Berrilli, Francesco

    2017-03-01

    Solar UV variability is extremely relevant for the stratospheric ozone. It has an impact on Earth's atmospheric structure and dynamics through radiative heating and ozone photochemistry. Our goal is to study the slope of the solar UV spectrum in two UV bands important to the stratospheric ozone production. In order to investigate the solar spectral variability, we use data from SOLSTICE (the Solar Stellar Irradiance Comparison Experiment) on board the Solar Radiation and Climate Experiment (SORCE) satellite. Datasets used are far UV (115-180 nm) and middle UV (180-310 nm), as well as the Mg II index (the Bremen composite). We introduce the SOLSTICE [FUV-MUV] colour to study the solar spectral characteristics, as well as to analyse the colour versus Mg II index. To isolate the 11-year scale variation, we used Empirical Mode Decomposition (EMD) on the datasets. The [FUV-MUV] colour strongly correlates with the Mg II index. The [FUV-MUV] colour shows a time-dependent behaviour when plotted versus the Mg II index. To explain this dependence we hypothesize an efficiency reduction of SOLSTICE FUV irradiance using an exponential ageing law.

  17. Solar activity cycle and the incidence of foetal chromosome abnormalities detected at prenatal diagnosis

    NASA Astrophysics Data System (ADS)

    Halpern, Gabrielle J.; Stoupel, Eliahu G.; Barkai, Gad; Chaki, Rina; Legum, Cyril; Fejgin, Moshe D.; Shohat, Mordechai

    1995-06-01

    We studied 2001 foetuses during the period of minimal solar activity of solar cycle 21 and 2265 foetuses during the period of maximal solar activity of solar cycle 22, in all women aged 37 years and over who underwent free prenatal diagnosis in four hospitals in the greater Tel Aviv area. There were no significant differences in the total incidence of chromosomal abnormalities or of trisomy between the two periods (2.15% and 1.8% versus 2.34% and 2.12%, respectively). However, the trend of excessive incidence of chromosomal abnormalities in the period of maximal solar activity suggests that a prospective study in a large population would be required to rule out any possible effect of extreme solar activity.

  18. Dynamic analysis of a closed-cycle solar adsorption refrigerator using two adsorbent-adsorbate pairs

    SciTech Connect

    Hajji, A. ); Worek, W. ); Lavan, Z. )

    1991-05-01

    In this paper a dynamic analysis of a closed-cycle, solar adsorption refrigerator is presented. The instantaneous and daily system performance are studied using two adsorbent-adsorbate pairs, Zeolite 13X-Water and Chabazite-Methanol. The effect of design and operating parameters, including inert material thermal capacitance, matrix porosity, and evaporation and condenser temperatures on the solar and cycle coefficients of performance are evaluated.

  19. Differences in Properties of 3He-rich SEP Events between Solar Cycle 24 and Earlier Cycles

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; Mason, G. M.; Ho, G. C.

    2013-12-01

    Since the launch of NASA's ACE spacecraft in 1997 we have been observing 3He-rich solar energetic particle (SEP) events using its ULEIS and SIS instruments. From those data it was determined that over the past 15+ years there has been a large variation in the fraction of time that energetic 3He could be detected near Earth, ranging from >80% near the maximum of solar cycle 23 to <2% in the minimum between cycles 23 and 24. In addition, it is now apparent that as the maximum of cycle 24 approaches this indicator of flare-related suprathermal ions is falling nearly a factor of 2 below the value observed in the previous cycle. The fraction of time with 3He present depends, however, on instrument sensitivity and thus our previous analyses did not directly address the question of whether the observed changes were due to the occurrence of fewer 3He-rich events with similar event characteristics, to having events with lower peak intensities and/or softer spectra, or to some combination of these effects. We have undertaken a more quantitative study of the solar cycle variation of 3He-rich SEP event properties to address this question. We use data from ACE and STEREO to characterize the events observed during the cycle 23/24 minimum and the cycle 24 maximum and compare them with ACE measurements from the cycle 23 maximum. In addition, we compare with published results obtained using instrumentation aboard ISEE-3 during the period spanning the maxima of cycles 21 and 22.

  20. A SOLAR CYCLE LOST IN 1793-1800: EARLY SUNSPOT OBSERVATIONS RESOLVE THE OLD MYSTERY

    SciTech Connect

    Usoskin, Ilya G.; Mursula, Kalevi; Arlt, Rainer; Kovaltsov, Gennady A.

    2009-08-01

    Because of the lack of reliable sunspot observations, the quality of the sunspot number series is poor in the late 18th century, leading to the abnormally long solar cycle (1784-1799) before the Dalton minimum. Using the newly recovered solar drawings by the 18-19th century observers Staudacher and Hamilton, we construct the solar butterfly diagram, i.e., the latitudinal distribution of sunspots in the 1790s. The sudden, systematic occurrence of sunspots at high solar latitudes in 1793-1796 unambiguously shows that a new cycle started in 1793, which was lost in the traditional Wolf sunspot series. This finally confirms the existence of the lost cycle that has been proposed earlier, thus resolving an old mystery. This Letter brings the attention of the scientific community to the need of revising the sunspot series in the 18th century. The presence of a new short, asymmetric cycle implies changes and constraints to sunspot cycle statistics, solar activity predictions, and solar dynamo theories, as well as for solar-terrestrial relations.

  1. ON POSSIBLE VARIATIONS OF BASAL Ca II K CHROMOSPHERIC LINE PROFILES WITH THE SOLAR CYCLE

    SciTech Connect

    Pevtsov, Alexei A.; Uitenbroek, Han; Bertello, Luca E-mail: huitenbroek@nso.edu

    2013-04-10

    We use daily observations of the Ca II K line profiles of the Sun-as-a-star taken with the Integrated Sunlight Spectrometer from 2006 December through 2011 July to deconvolve the contributions from the quiet (basal) chromosphere and with magnetic network/plage areas. The 0.5 A emission index computed from basal profiles shows a significantly reduced modulation (as compared with one derived from the observed profiles) corresponding to the Sun's rotation. For basal contribution of the Ca II K line, the peak in power spectrum corresponding to solar rotation is broad and not well defined. Power spectra for the plage contribution show two narrow well-defined peaks corresponding to solar rotation at two distinct latitudes, in agreement with the latitudinal distribution of activity on the Sun at the end of Cycle 23 and beginning of Cycle 24. We use the lack of a signature of solar rotation in the basal (quiet Sun) component as an indication of a successful removal of the active Sun (plage) component. Even though the contribution from solar activity is removed from the basal line profiles, we find a weak dependency of intensity in the line core (K3) of basal profiles with the phase of the solar cycle. Such dependency could be the result of changes in thermal properties of basal chromosphere with the solar cycle. As an alternative explanation, we also discuss a possibility that the basal component does not change with the phase of the solar cycle.

  2. Observations of Solar Spectral Irradiance Change During Cycle 22 from NOAA-9 SBUV/2

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Cebula, Richard P.; Hilsenrath, Ernest

    2003-01-01

    The NOM-9 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument is one of a series of instruments providing daily solar spectral irradiance measurements in the middle and near ultraviolet since 1978. The SBUV/2 instruments are primarily designed to measure stratospheric profile and total column ozone, using the directional albedo as the input to the ozone processing algorithm. As a result, the SBUV/2 instrument does not have onboard monitoring of all time-dependent response changes. We have applied internal comparisons and vicarious (external) comparisons to determine the long-term instrument characterization for NOAA-9 SBUV/2 to derive accurate solar spectral irradiances from March 1985 to May 1997 spanning two solar cycle minima with a single instrument. The NOAA-9 data show an amplitude of 9.3(+/- 2.3)% (81-day averaged) at 200-205 nm for solar cycle 22. This is consistent with the result of (Delta)F(sub 200-205) = 8.3(+/- 2.6)% for cycle 21 from Nimbus-7 SBUV and (Delta)F(sub 200-205) = 10(+/- 2)% (daily values) for cycle 23 from UARS SUSIM. NOAA-9 data at 245-250 nm show a solar cycle amplitude of (Delta)F(sub 245-250) = 5.7(+/- 1.8)%. NOAA-9 SBUV/2 data can be combined with other instruments to create a 25-year record of solar UV irradiance.

  3. Theoretical study of the seasonal and solar cycle variations of stable aurora red arcs

    SciTech Connect

    Kozyra, J.U.; Valladares, C.E.; Carlson, H.C.; Buonsanto, M.J.; Slater, D.W.

    1990-08-01

    SAR arc statistic provide information on the seasonal and solar cycle variations in the subauroral region electron temperature peak and associated magnetospheric energy source. There are two sources of long-term (solar cycle and seasonal) variability in the magnitude of the subauroral region electron temperature peak and associated SAR are emission intensity: (1) the neutral atmosphere and ionosphere and (2) the magnetospheric energy source. The results of this study indicate that the observed seasonal variation in SAR are intensities can be explained reasonably well by seasonal variations in the neutral atmosphere and ionosphere. True solstice effect are unlikely to result from difference in a near-equatorial magnetospheric heat source since the same heat source supplies both the summer and the winter hemispheres at opposite ends of a common flux tube. Observed solar cycle variations in SAR are intensity for a fixed ring current strength (as represented by the D sub st index) are not consistent with variations predicted solely on the basis of a solar cycle changes in the neutral atmosphere and ionosphere. A reduction of the magnetospheric heat flux by a factor of between 5 and 20 from solar maximum to solar minimum conditions is necessary to bring model electron temperatures and 6300 emission intensity into agreement with observational results for moderately disturbed conditions D sub st approx - 80 gamma. The required reduction in the magnetospheric energy source with decreasing solar cycle is attributed to compositional changes in the magnetospheric plasma.

  4. The Effects of a Nearly 100% Duty Cycle in Observations of Solar Oscillations

    NASA Technical Reports Server (NTRS)

    Hill, F.

    1984-01-01

    Power spectra of window functions with duty cycles between 80% and 99% and with randomly spaced gaps are compared and their effect on observations of solar oscillations are discussed. It is found that for all the cases, observations of solar oscillations would not be severely impacted as long as the gap structure is random rather than periodic.

  5. Relationships between solar activity and climate change. [sunspot cycle effects on lower atmosphere

    NASA Technical Reports Server (NTRS)

    Roberts, W. O.

    1974-01-01

    Recurrent droughts are related to the double sunspot cycle. It is suggested that high solar activity generally increases meridional circulations and blocking patterns at high and intermediate latitudes, especially in winter. This effect is related to the sudden formation of cirrus clouds during strong geomagnetic activity that originates in the solar corpuscular emission.

  6. Effects of Solar UV Radiation and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    EPA Science Inventory

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions...

  7. The temperature of quiescent streamers during solar cycles 23 and 24

    SciTech Connect

    Landi, E.; Testa, P.

    2014-05-20

    Recent in-situ determinations of the temporal evolution of the charge state distribution in the fast and slow solar wind have shown a general decrease in the degree of ionization of all the elements in the solar wind along solar cycles 23 and 24. Such a decrease has been interpreted as a cooling of the solar corona which occurred during the decline and minimum phase of solar cycle 23 from 2000 to 2010. In the present work, we investigate whether spectroscopic determinations of the temperature of the quiescent streamers show signatures of coronal plasma cooling during cycles 23 and 24. We measure the coronal electron density and thermal structure at the base of 60 quiescent streamers observed from 1996 to 2013 by SOHO/SUMER and Hinode/EIS and find that both quantities do now show any significant dependence on the solar cycle. We argue that if the slow solar wind is accelerated from the solar photosphere or chromosphere, the measured decrease in the in-situ wind charge state distribution might be due to an increased efficiency in the wind acceleration mechanism at low altitudes. If the slow wind originates from the corona, a combination of density and wind acceleration changes may be responsible for the in-situ results.

  8. Anomalous Expansion of Coronal Mass Ejections During Solar Cycle 24 and Its Space Weather Implications

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Michalek, Grzegorz

    2014-01-01

    The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by approximately 40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle.

  9. ON THE VARIATION OF SOLAR RADIUS IN ROTATION CYCLES

    SciTech Connect

    Qu, Z. N.; Kong, D. F.; Xiang, N. B.; Feng, W.

    2015-01-10

    The Date Compensated Discrete Fourier Transform and CLEANest algorithm are used to study the temporal variations of the solar radius observed at Rio de Janeiro Observatory from 1998 March 2 to 2009 November 6. The CLEANest spectra show several significant periodicities around 400, 312, 93.5, 86.2, 79.4, 70.9, 53.2, and 26.3 days. Then, combining the data on the daily solar radius measured at Calern Observatory and Rio de Janeiro Observatory and the corresponding daily sunspot areas, we study the short-term periodicity of the solar radius and the role of magnetic field in the variation of the solar radius. The rotation period of the daily solar radius is determined to be statistically significant. Moreover, its temporal evolution is anti-phase with that of sunspot activity, and it is found anti-phase with solar activity. Generally, the stronger solar activity is, the more obvious is the anti-phase relation of radius with solar activity. This indicates that strong magnetic fields have a greater inhibitive effect than weak magnetic fields on the variation of the radius.

  10. Life Cycle Greenhouse Gas Emissions from Solar Photovoltaics (Fact Sheet)

    SciTech Connect

    Not Available

    2012-11-01

    The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that helps to clarify inconsistent and conflicting life cycle GHG emission estimates in the published literature and provide more precise estimates of life cycle GHG emissions from PV systems.

  11. Coronal Dynamic Activities in the Declining Phase of a Solar Cycle

    NASA Astrophysics Data System (ADS)

    Jang, Minhwan; Woods, T. N.; Hong, Sunhak; Choe, G. S.

    2016-12-01

    It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the evolution of polar and low-latitude coronal hole (CH) areas, splitting and merging events of CHs, and coronal mass ejections (CMEs) detected by SOHO/LASCO C3 in solar cycle 23. Although the total CH area is at its maximum near the sunspot minimum, in which polar CHs prevail, it shows a comparable second maximum in the declining phase of the cycle, in which low-latitude CHs are dominant. The events of CH splitting or merging, which are attributed to surface motions of magnetic fluxes, are also mostly populated in the declining phase of the cycle. The far-reaching C3 CMEs are also overpopulated in the declining phase of the cycle. From these results we suggest that solar dynamic activities due to the horizontal surface motions of magnetic fluxes extend far in the declining phase of the sunspot cycle.

  12. The study of the solar cycle and its irregularities using dynamo models

    NASA Astrophysics Data System (ADS)

    Binay Karak, Bidya

    The solar cycle is not regular. The strength as well as the period varies from cycle to cycle. One puzzling aspect of this sunspot cycle is the Maunder minimum in 17th century when sunspots disappeared for about 70 years. Indirect studies suggest that there were several other such events in the past. The motivation of our work will be first to understand the generation and the evolution of the large-scale magnetic field of the Sun and then to model some irregular features of the solar cycle. We shall present a flux transport dynamo model to study the evolution of magnetic fields in the Sun. In this model the toroidal field is generated by the strong differential rotation near the base of the convection zone and the poloidal field is generated near the solar surface from the decay of sunspots. The turbulent diffusion, the meridional circulation and the turbulent pumping are the important flux transport agents in this model which communicate these two spatially segregated source regions of the magnetic field. With this dynamo model, the speaker shall explain several aspects of the solar cycle including the grand minima. We shall also discuss the predictability of the future solar cycle using dynamo models.

  13. Two Types of Coronal Bright Points in the 24-th Cycle of Solar Activity

    NASA Astrophysics Data System (ADS)

    Sherdanov, Chori T.; Minenko, Ekaterina P.; Tillaboev, A. M.; Sattarov, Isroil

    We applied an automatic program for identification of coronal bright points (CBPs) to the data obtained by SOHO/EIT observations taken at the wavelength 195 Å, in the time interval from the end of the 23rd to the early 24th solar cycle. We studied the total number of CBPs and its variations at the beginning of the given cycle of solar activity, so that the development of the solar activity could be predicted with the use of CBPs. For a primary reference point for the 24th solar cycle, we took the emergence of a high-latitude sunspot with the reversed polarity, which appeared in January, 2008. We show that the observed number of CBPs reaches the highest point around the minimum of the solar activity, which in turn may result from the effect of visibility. The minimum solar activity at this time provides the opportunity to register the number of CBPs with the highest accuracy, with its uniform latitudinal distribution. We also study the properties of CBPs in a new 24th cycle of solar activity. It is shown that variations in the cyclic curve of the number of coronal bright points associated with variations in the solar activity, for the latitudes of the quiet Sun to be anticorrelation characteristic changes in the number CBPs to the solar activity, and the observational data are for the regions of active formations on the Sun almost identical on character on the equatorial latitude, but this have lightly expressed character in high-latitude zone. To explain the cyclic curves of variation in the number of coronal bright points in connection with the solar cycle in different latitudinal zones, we suggest a hypothesis of the existence of two types of coronal bright points: those associated with the quiet corona and those related to active formations.

  14. Principal Component Analysis of Solar Background and Sunspot Magnetic Field in cycles 21-24 and its implications for the solar activity prediction in cycles 25-27

    NASA Astrophysics Data System (ADS)

    Zharkova, Valentina; Popova, Helen; Zharkov, Sergei; Shepherd, Simon

    Principle component analysis (PCA) of the solar background magnetic field (SBMF) measured from Wilcox Solar Observatory (WSO) and sunspot magnetic field (SMF) measured by SOHO/MDI magnetograms reveals the two principal components (PCs) of waves travelling in time. In addition, the independent components analysis helps to uncover 8 pairs of SBMF waves in latitudes: two large symmetric magnetic waves , which are the same for all cycles 21-23, and three pairs of asymmetric magnetic waves, which are unique for each cycle. In each pair the waves travel slightly off phase with different phase shift for each cycle and have a different number of equator crossings (Zharkova et al, 2012). These SBMF variations are assumed to be those of poloidal magnetic field traveling slightly off-phase from pole to pole which are caused by a joint action of dipole and quadruple magnetic sources in the Sun. The simulations with the two layer Parker's dynamo model with meridional circulation revealed that the dominant pair of PCs can be produced by a magnetic dipole accounting for the two main dynamo waves operating between the two magnetic poles. The further three pairs of the waves are unique to each cycle and associated with the multiple magnetic sources in the solar interior: with a quadruple symmetry in both layers for cycle 21, with quadruple magnetic sources in the upper layer and dipole sources in the inner layer for cycle 22 and with the quadruple magnetic sources in the inner layer and the dipole sources in the upper layer for cycle 23 (Popova et al, 2013). The PCs derived for all three cycles from SMBF were used as a training set for the magnetic wave prediction for the cycles 24-27 by using Hamiltonian approach (Shepherd and Zharkova, 2014) and verifying by the SBMF observations in the current cycle 24. The prediction results indicate that the solar activity is defined mainly by the solar background magnetic fields while the sunspots and their magnetic fields seem to be

  15. Sunspot group tilt angles and the strength of the solar cycle

    NASA Astrophysics Data System (ADS)

    Dasi-Espuig, M.; Solanki, S. K.; Krivova, N. A.; Cameron, R.; Peñuela, T.

    2010-07-01

    Context. It is well known that the tilt angles of active regions increase with their latitude (Joy's law). It has never been checked before, however, whether the average tilt angles change from one cycle to the next. Flux transport models show the importance of tilt angles for the reversal and build up of magnetic flux at the poles, which is in turn correlated to the strength of the next cycle. Aims: Here we analyse time series of tilt angle measurements and look for a possible relationship of the tilt angles with other solar cycle parameters, in order to glean information on the solar dynamo and to estimate their potential for predicting solar activity. Methods: We employed tilt angle data from Mount Wilson and Kodaikanal observatories covering solar cycles 15 to 21. We analyse the latitudinal distribution of the tilt angles (Joy's law), their variation from cycle to cycle, and their relationship to other solar cycle parameters, such as the strength (or total area covered by sunspots in a cycle), amplitude, and length. Results: The two main results of our analysis follow. 1. We find an anti-correlation between the mean normalised tilt angle of a given cycle and the strength (or amplitude) of that cycle, with a correlation coefficient of rc = -0.95 (99.9% confidence level) and rc = -0.93 (99.76% confidence level) for Mount Wilson and Kodaikanal data, respectively. 2. The product of the cycle's averaged tilt angle and the strength of the same cycle displays a significant correlation with the strength of the next cycle (rc = 0.65 at 89% confidence level and rc = 0.70 at 92% confidence level for Mount Wilson and Kodaikanal data, respectively). An even better correlation is obtained between the source term of the poloidal flux in Babcock-Leighton-type dynamos (which contains the tilt angle) and the amplitude of the next cycle. Further we confirm the linear relationship (Joy's law) between the tilt angle and latitude with slopes of 0.26 and 0.28 for Mount Wilson and

  16. Variations in meteor heights at 22.7°S during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Lima, L. M.; Araújo, L. R.; Alves, E. O.; Batista, P. P.; Clemesha, B. R.

    2015-10-01

    The meteor radar measurements obtained at Cachoeira Paulista (22.7°S), Brazil, have been used to study a possible relationship between meteor echo height variations and solar flux during solar cycle 23. A good concordance between the normalized values of the annual mean of the meteor peak heights and F10.7 solar radio flux and Mg_II solar indexes have been observed during declining phase of the solar cycle 23. After eliminating the solar activity influence, the annual mean of the meteor echo peak heights showed a linear decrease of 30 m/year when Mg_II solar index is used and 38 m/year when F10.7 solar radio flux is used. When the trend is eliminated the relationship between meteor peak heights and F10.7 solar flux indicate a trend of 672 m/100 sfu (sfu-solar flux unit). The meteor amplitude signals and the decay time drops after mid-2004, which may be attributed to the decreasing of the electron density in the meteor trails. The meteor echo peak height decrease has been interpreted as being caused by a reduction in air density in the upper atmosphere.

  17. Monthly variations of the Caspian sea level and solar activity.

    NASA Astrophysics Data System (ADS)

    Romanchuk, P. R.; Pasechnik, M. N.

    The connection between 11-year cycle of solar activity and the Caspian sea level is investigated. Seasonal changes of the Caspian sea level and annual variations of the sea level with variations of solar activity are studied. The results of the verifications of the sea level forecasts obtained with application of the rules discovered by the authors are given.

  18. HMI Observations of Solar Flares in Cycle 24

    NASA Astrophysics Data System (ADS)

    Hoeksema, J. Todd; Bobra, Monica; Couvidat, Sebastien; Sun, Xudong

    2015-08-01

    The Helioseismic and Magnetic Imager (HMI) on NASA’s Solar Dynamics Observatory (SDO) has continuously measured the vector magnetic field, intensity, and Doppler velocity in solar flares and over the entire solar disk since May 2010. The regular cadence of 45 seconds for line-of-sight and 12 minutes for vector measurements enables reliable investigations of photospheric conditions before, during, and after events both locally and globally. Active region indices can be tracked and conditions in the overlying corona can be modeled. A few examples show the utility of the data and demonstrate that some care must be exercised when the HMI data are used to investigate time variations.

  19. Trisomy 13 (Patau syndrome) with an 11-year survival.

    PubMed

    Zoll, B; Wolf, J; Lensing-Hebben, D; Pruggmayer, M; Thorpe, B

    1993-01-01

    Trisomy 13 is very rare in live-born children. Only a small number of these children survive the first year and very few cases are reported to live longer. Survival time depends partly on the cytogenetic findings--full trisomy 13 or trisomy 13 mosaicism--and partly on the existence of serious somatic malformations. We report on a 11-year-old girl with full trisomy 13. In this case, missing cerebral and cardiovascular malformations probably allowed the long survival.

  20. Technology for Bayton-cycle powerplants using solar and nuclear energy

    NASA Technical Reports Server (NTRS)

    English, R. E.

    1986-01-01

    Brayton cycle gas turbines have the potential to use either solar heat or nuclear reactors for generating from tens of kilowatts to tens of megawatts of power in space, all this from a single technology for the power generating system. Their development for solar energy dynamic power generation for the space station could be the first step in an evolution of such powerplants for a very wide range of applications. At the low power level of only 10 kWe, a power generating system has already demonstrated overall efficiency of 0.29 and operated 38 000 hr. Tests of improved components show that these components would raise that efficiency to 0.32, a value twice that demonstrated by any alternate concept. Because of this high efficiency, solar Brayton cycle power generators offer the potential to increase power per unit of solar collector area to levels exceeding four times that from photovoltaic powerplants using present technology for silicon solar cells. The technologies for solar mirrors and heat receivers are reviewed and assessed. This Brayton technology for solar powerplants is equally suitable for use with the nuclear reactors. The available long time creep data on the tantalum alloy ASTAR-811C show that such Brayton cycles can evolve to cycle peak temperatures of 1500 K (2240 F). And this same technology can be extended to generate 10 to 100 MW in space by exploiting existing technology for terrestrial gas turbines in the fields of both aircraft propulsion and stationary power generation.

  1. Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies

    NASA Astrophysics Data System (ADS)

    Munoz-Jaramillo, Andres; Dasi-Espuig, M.; Balmaceda, L. A.; DeLuca, E. E.

    2013-07-01

    In the simplest of forms, modern dynamo theory describes the solar cycle as a process that takes the solar magnetic field (back and forth) from a configuration that is predominantly poloidal (contained inside the meridional plane), to one predominantly toroidal (wrapped around the axis of rotation). However, there is still uncertainty and controversy in the detailed understanding of this process. A major contributor to this uncertainty is the lack of direct long-term databases covering different components of the solar magnetic field (an issue mainly affecting the poloidal component of the solar magnetic field). In this talk we will review the different observations that can be used as proxies for the solar magnetic field (in absence of direct magnetic observations). I will present a recently standardized database that can be used as a proxy for the evolution of the polar magnetic field. And to conclude, I will show the insights that can be gained (by taking advantage of this database) in the context of the transition between the toroidal and poloidal phases of the cycle, solar cycle memory as determined by the different mechanisms of flux transport, and the practical goal of solar cycle prediction.

  2. Statistical study of strong and extreme geomagnetic disturbances and solar cycle characteristics

    NASA Astrophysics Data System (ADS)

    Kilpua, Emilia; Nigul, Olspert; Grigorievskiy, Alexander; Käpylä, Maarit; Tanskanen, Eija; Kataoka, Ryuho; Miyahara, Hiroko; Pelt, Jaan; Ying, Liu

    2016-04-01

    Extreme space weather storms are low-probability, but high-consequence events that may have a significant impact on the modern technological infrastructure in space and on ground. We present here the results on the correlation analysis between the occurrence of extreme geomagnetic storms and solar cycle characteristics using an extensive geomagnetic index AA data set spanning over 150 years (13 solar cycles) complemented by the Kakioka magnetometer recordings. Our results show that the correlation between the storm occurrence and the strength of solar cycle decreases from a clear positive correlation with increasing storm magnitude towards a negligible relationship. Hence, also the calmer Sun can launch super-storms. Examples of such events are the Carrington storm in 1859 and the July 2012 CME that impacted the STEREO-A spacecraft, both of which occurred during relatively weak solar cycles. Our results further suggest that while weaker storms occur most frequently in the declining phase the most extreme storms have a tendency to occur near solar maximum. We also discuss the implications of our findings for the connection between the extreme solar eruptions and multi-scale solar dynamo generated magnetic fields.

  3. Probability density functions for the variable solar wind near the solar cycle minimum

    NASA Astrophysics Data System (ADS)

    Vörös, Z.; Leitner, M.; Narita, Y.; Consolini, G.; Kovács, P.; Tóth, A.; Lichtenberger, J.

    2015-08-01

    Unconditional and conditional statistics are used for studying the histograms of magnetic field multiscale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year in 2008. The conditional statistics involves the magnetic field time series split into concatenated subsets of data according to a threshold in dynamic pressure. The threshold separates fast-stream leading edge compressional and trailing edge uncompressional fluctuations. The histograms obtained from these data sets are associated with both multiscale (B) and small-scale (δB) magnetic fluctuations, the latter corresponding to time-delayed differences. It is shown here that, by keeping flexibility but avoiding the unnecessary redundancy in modeling, the histograms can be effectively described by a limited set of theoretical probability distribution functions (PDFs), such as the normal, lognormal, kappa, and log-kappa functions. In a statistical sense the model PDFs correspond to additive and multiplicative processes exhibiting correlations. It is demonstrated here that the skewed small-scale histograms inherent in turbulent cascades are better described by the skewed log-kappa than by the symmetric kappa model. Nevertheless, the observed skewness is rather small, resulting in potential difficulties of estimation of the third-order moments. This paper also investigates the dependence of the statistical convergence of PDF model parameters, goodness of fit, and skewness on the data sample size. It is shown that the minimum lengths of data intervals required for the robust estimation of parameters is scale, process, and model dependent.

  4. Solar-cycle variations of large frequency separations of acoustic modes: implications for asteroseismology

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Chaplin, W. J.; Elsworth, Y.; New, R.

    2011-06-01

    We have studied solar-cycle changes in the large frequency separations that can be observed in Birmingham Solar Oscillations Network (BiSON) data. The large frequency separation is often one of the first outputs from asteroseismic studies because it can help constrain stellar properties like mass and radius. We have used three methods for estimating the large separations: use of individual p-mode frequencies, computation of the autocorrelation of frequency-power spectra, and computation of the power spectrum of the power spectrum. The values of the large separations obtained by the different methods are offset from each other and have differing sensitivities to the realization noise. A simple model was used to predict solar-cycle variations in the large separations, indicating that the variations are due to the well-known solar-cycle changes to mode frequency. However, this model is only valid over a restricted frequency range. We discuss the implications of these results for asteroseismology.

  5. The importance of facular and plage data for the understanding of the solar cycle

    NASA Astrophysics Data System (ADS)

    Petrovay, Kristof

    Most global analyses of the solar activity cycle are based on sunspot data as other indicators such as F10.8 or flare data only cover the last few solar cycles. The only solar activity param-eter covering a historically significant time span is the facular area data set in the Greenwich catalogue. In this poster we first demonstrate the use of such data for the study of the solar cycle by considering similarities and differences in the Waldmeier effect in faculae as opposed to sunspots. The Greenwich catalogue was discontinued in 1976, so the extension of such studies to more recent times relies on "proxy" data such as plage areas; however, due to the short overlap in time, cross-calibration of these data has not been consistently made. We discuss the possibilities offered by SDO to cross-correlate facular areas with their proxies and to set up a new systematic data set of these activity indices.

  6. Comparing the solar magnetic field in the corona and in the inner heliosphere during solar cycles 21-23

    NASA Astrophysics Data System (ADS)

    Virtanen, I. I.; Mursula, K.

    2009-04-01

    We compare the open solar magnetic field estimated by the PFSS model based on the WSO photospheric field observations, with the inner heliospheric magnetic field. We trace the observed radial HMF into the coronal PFSS boundary at 2.5 solar radii using the observed solar wind velocity, and determine the PFSS model field at the line-of-sight footpoint. Comparing the two field values, we calculate the power n of the apparent decrease of the radial field. According to expectations based on Maxwell's equations, also reproduced by Parker's HMF model, the radial HMF field should decrease with n=2. However, comparison gives considerably lower values of n, indicating the effect of HCS in the PFSS model and the possible superexpansion. The n values vary with solar cycle, being roughly 1.3-1.4 at minima and about 1.7 at maxima. Interestingly, the n values for the two HMF sectors show systematic differences in the late declining to minimum phase, with smaller n values for the HMF sector dominant in the northern hemisphere. This is in agreement with the smaller field value in the northern hemisphere and the southward shifted HCS, summarized by the concept of the bashful ballerina. We also find that the values of n during the recent years, in the late declining phase of solar cycle 23, are significantly larger than during the same phase of the previous cycles. This agrees with the exceptionally large tilt of the solar dipole at the end of cycle 23. We also find that the bashful ballerina appears even during SC 23 but the related hemispheric differences are smaller than during the previous cycles.

  7. Starspots, stellar cycles and stellar flares: Lessons from solar dynamo models

    NASA Astrophysics Data System (ADS)

    Choudhuri, Arnab Rai

    2017-01-01

    In this review, we discuss whether the present solar dynamo models can be extrapolated to explain various aspects of stellar activity. We begin with a summary of the following kinds of data for solar-like stars: (i) data pertaining to stellar cycles from Ca H/K emission over many years; (ii) X-ray data indicating hot coronal activity; (iii) starspot data (especially about giant polar spots); and (iv) data pertaining to stellar superflares. Then we describe the current status of solar dynamo modelling—giving an introduction to the flux transport dynamo model, the currently favoured model for the solar cycle. While an extrapolation of this model to solar-like stars can explain some aspects of observational data, some other aspects of the data still remain to be theoretically explained. It is not clear right now whether we need a different kind of dynamo mechanism for stars having giant starspots or producing very strong superflares.

  8. An investigation of the solar cycle response of odd-nitrogen in the thermosphere

    NASA Technical Reports Server (NTRS)

    Rusch, David W.; Solomon, Stanley C.

    1992-01-01

    This annual report covers the first year of funding for the study of the solar cycle variations of odd-nitrogen (N((sup 2)D), N((sup 4)S), NO) in the Earth's thermosphere. The study uses the extensive data base generated by the Atmosphere Explorer (AE) satellites, and the Solar Mesosphere Explorer Satellite. The AE data are being used, for the first time, to define the solar variability effect on the odd-nitrogen species through analysis of the emissions at 520 nano-m from N((sup 2)D) and the emission from O(+)((sup 2)P). Additional AE neutral and ion density data are used to help define and quantify the physical processes controlling the variations. The results from the airglow study will be used in the next two years of this study to explain the solar cycle changes in NO measured by the Solar Mesosphere Explorer.

  9. Porcupine feeding scars and climatic data show ecosystem effects of the solar cycle.

    PubMed

    Klvana, Ilya; Berteaux, Dominique; Cazelles, Bernard

    2004-09-01

    Using North American porcupine (Erethizon dorsatum) feeding scars on trees as an index of past porcupine abundance, we have found that porcupine populations have fluctuated regularly over the past 130 years in the Bas St. Laurent region of eastern Quebec, with superimposed periodicities of 11 and 22 years. Coherency and phase analyses showed that this porcupine population cycle has closely followed the 11- and 22-year solar activity cycles. Fluctuations in local precipitation and temperature were also cyclic and closely related to both the solar cycle and the porcupine cycle. Our results suggest that the solar cycle indirectly sets the rhythm of population fluctuations of the most abundant vertebrate herbivore in the ecosystem we studied. We hypothesize that the solar cycle has sufficiently important effects on the climate along the southern shore of the St. Lawrence estuary to locally influence terrestrial ecosystem functioning. This constitutes strong evidence for the possibility of a causal link between solar variability and terrestrial ecology at the decadal timescale and local spatial scale, which confirms results obtained at greater temporal and spatial scales.

  10. Solar Cycle Slow to Get Going: What Does It Mean for Space Weather?

    NASA Astrophysics Data System (ADS)

    Turner, Ronald

    2011-04-01

    If you have the sense that the current solar cycle has been slow to build up, maybe it is more than just the “watched pot” failing to boil. A comparison with previous sunspot cycles shows that the current cycle is among the slowest-growing cycles characterized with good historical data. Figure 1 shows the smoothed sunspot number for the period from 2 years before the minimum to 2 years after it for the 24 numbered solar cycles (cycle 1 started in 1755; we are just now entering cycle 24). It illustrates the historically slow increase of the current cycle (shown in red) as of February 2011. Three of the four cycles with slower increases (shown in blue) were during the Dalton Minimum in the early nineteenth century. The fourth is the period leading into cycle 1. The red dots in the figure are cycle 24 monthly average sunspot numbers; these data are too recent to be adjusted by the smoothing algorithm that includes the influence of monthly averages within 6 months of the smoothed value. Also shown, at the bottom of the figure, for context, are the sunspot data for the first 23 cycles, which also identify the Dalton Minimum.

  11. Solar-cycle variation of the plasmasphere observed from the Akebono PWS data

    NASA Astrophysics Data System (ADS)

    Hasegawa, S.; Miyoshi, Y.; Kitamura, N.; Keika, K.; Kumamoto, A.; Machida, S.

    2013-12-01

    Plasmaspheric density structures have been studied for a long time. Although it has been clarified that the density is roughly constant along field lines in the outer plasmasphere [Goldstein et al., 2001; Denton et al., 2002, 2004], field-aligned density distributions of the inner plasmasphere has not been studied intensively. Moreover, continuous observation results longer than one-solar cycle have not been reported. Consequently, long-term variations of the plasmaspheric density over a solar cycle remains unknown. In this study, using electron density data based on plasma wave observations from the PWS experiments on board the Akebono satellite from 1989 to 2008, we conduct statistical analyses on variations of structures of the plasmasphere and plasmatrough. First, we select PWS data during geomagnetically quiet periods ( Kp less than or equal to 3 and Dst greater than or equal to -50 nT ), and derive spatial distributions as a function of L-magnetic local time and altitude-magnetic latitude. Second, assuming that densities along field lines are a function of geocentric distance R at an altitude of higher than 4000 km, we estimate the equatorial density and field-aligned density distributions. The equatorial plasma density and field-aligned density distributions depend on the L shell and the solar cycle. At small L shells ( L less than 3.7 ), field-aligned distributions do not clearly depend on solar cycle, and the estimated equatorial density tends to be small during the solar minimum. At large L shells ( L larger than or equal to 3.7 ) including the plasma trough and outside the plasmapause, on the other hand, field-aligned distributions vary with the solar cycle and the density tends to be low during the solar minimum. The equatorial density at the solar minimum is higher than that at the solar maximum.

  12. Performance analysis of a solar-powered organic rankine cycle engine.

    PubMed

    Bryszewska-Mazurek, Anna; Swieboda, Tymoteusz; Mazurek, Wojciech

    2011-01-01

    This paper presents the performance analysis of a power plant with the Organic Rankine Cycle (ORC). The power plant is supplied by thermal energy utilized from a solar energy collector. R245fa was the working fluid in the thermodynamic cycle. The organic cycle with heat regeneration was built and tested experimentally. The ORC with a heat regenerator obtained the maximum thermodynamic efficiency of approximately 9%.

  13. SUSIM Measurements of UV Variations During the Decline of Solar Cycle 22

    NASA Astrophysics Data System (ADS)

    Floyd, L. E.; Crane, P. C.; Herring, L. C.; Prinz, D. K.; Brueckner, G. E.

    1997-05-01

    The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) aboard the Upper Atmosphere Research Satellite (UARS) has measured the solar spectral irradiance for wavelengths 1150-4100 { Angstroms} on every available day from October 11, 1991 to the present. The record of spectral irradiances obtained during this period clearly shows the decline associated with the last half of solar cycle 22. Superimposed on this solar cycle variation is a 27-day solar rotation modulation which, for the most part, maintains coherence across the wavelength spectrum and with SUSIM's own Mg II core-to-wing ratio index. However, for wavelengths between the Si I edge at 1682 { Angstroms} and the Mg I edge at 2513 { Angstroms} and for some time periods, 13.5-day variations dominate. SUSIM observations began when solar activity was near maximum and now extend through minimum. Generally, the measured peak-to-peak variations are larger for shorter wavelengths and for emission or absorption lines. The wavelength dependence of the UV variability apparently corresponds to the solar atmospheric emission heights given by radiative transfer models. The largest measured variation, that for H I Ly-alpha , exceeds a factor of two. The variation in the continuum just shortward of the Al I edge at 2076 { Angstroms} is about 10%; just longward, about 5%. This latter variation continues up to the Mg I edge and then declines to approximately zero measured variation at about 3000 { Angstroms} and above. Based on common proxies of solar UV variation, such as the Mg II core-to-wing ratio and He I 10830 { Angstroms} equivalent width, SUSIM irradiance measurements have ranged over more than 85% of the entire solar cycle 22 variation. Through the separate use of each index as a UV proxy, we extend the SUSIM measurements to estimate the wavelength-dependent peak-to-peak UV variability over the whole of solar cycle 22. SUSIM is supported under NASA-Defense Purchase Request S14798D.

  14. Scale Height variations with solar cycle in the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Milan, Stephen E.; Hall, Benjamin E. S.; Cartacci, Marco; Radicella, Sandro M.; Blelly, Pierre-Louis

    2015-04-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on board the Mars Express spacecraft has been probing the topside of the ionosphere of Mars since June 2005, covering currently almost one solar cycle. A good knowledge of the behaviour of the ionospheric variability for a whole solar period is essential since the ionosphere is strongly dependent on solar activity. Using part of this dataset, covering the years 2005 - 2012, differences in the shape of the topside electron density profiles have been observed. These variations seem to be linked to changes in the ionospheric temperature due to the solar cycle variation. In particular, Mars' ionospheric response to the extreme solar minimum between end-2007 and end-2009 followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to internal origin of the magnetic field between both planets. Plasma parameters such as the scale height as a function of altitude, the main peak characteristics (altitude, density), the total electron content (TEC), the temperatures, and the ionospheric thermal pressures show variations related to the solar cycle. The main changes in the topside ionosphere are detected during the period of very low solar minimum, when ionospheric cooling occurs. The effect on the scale height is analysed in detail. In contrast, a clear increase of the scale height is observed during the high solar activity period due to enhanced ionospheric heating. The scale height variation during the solar cycle has been empirically modelled. The results have been compared with other datasets such as radio-occultation and retarding potential analyser data from old missions, especially in low solar activity periods (e.g. Mariner 4, Viking 1 and 2 landers), as well as with numerical modelling.

  15. SOLAR CYCLE VARIATIONS OF THE RADIO BRIGHTNESS OF THE SOLAR POLAR REGIONS AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

    SciTech Connect

    Nitta, Nariaki V.; DeRosa, Marc L.

    2014-01-10

    We have analyzed daily microwave images of the Sun at 17 GHz obtained with the Nobeyama Radioheliograph (NoRH) in order to study the solar cycle variations of the enhanced brightness in the polar regions. Unlike in previous works, the averaged brightness of the polar regions is obtained from individual images rather than from synoptic maps. We confirm that the brightness is anti-correlated with the solar cycle and that it has generally declined since solar cycle 22. Including images up to 2013 October, we find that the 17 GHz brightness temperature of the south polar region has decreased noticeably since 2012. This coincides with a significant decrease in the average magnetic field strength around the south pole, signaling the arrival of solar maximum conditions in the southern hemisphere more than a year after the northern hemisphere. We do not attribute the enhanced brightness of the polar regions at 17 GHz to the bright compact sources that occasionally appear in synthesized NoRH images. This is because they have no correspondence with small-scale bright regions in images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory with a broad temperature coverage. Higher-quality radio images are needed to understand the relationship between microwave brightness and magnetic field strength in the polar regions.

  16. On the dynamically driven temperature response in the middle atmosphere to the solar cycle signal.

    NASA Astrophysics Data System (ADS)

    Karlsson, Bodil; Kuilman, Maartje

    2016-04-01

    Noctilucent clouds (NLC), formed in the summer polar mesosphere, are exposed to solar radiation around the clock. These clouds consist of water ice, and are thus expected to be sensitive to changes in the solar Lyman alpha flux since it efficiently destroys water vapor in this region. Moreover, during solar maxima, the upper parts of the atmosphere are in general significantly warmer due to physical and chemical processes that are intensified at high solar activity. It is thus surprising that a clear solar cycle signal in NLC is hard to trace. We investigate how the circulation in the summer mesosphere is affected by changes in the solar flux using a 30-year run from the extended and nudged version of the Canadian Middle Atmosphere Model (CMAM30). We find that, as a result of a chain of wave-mean flow interactions primarily initiated in the winter stratosphere, the solar cycle signal from direct solar heating is suppressed by an enhanced circulation which adiabatically cools the region at increased solar activity.

  17. Contextualizing Solar Cycle 24: Report on the Development of a Homogenous Database of Bipolar Active Regions Spanning Four Cycles

    NASA Astrophysics Data System (ADS)

    Munoz-Jaramillo, A.; Werginz, Z. A.; DeLuca, M. D.; Vargas-Acosta, J. P.; Longcope, D. W.; Harvey, J. W.; Martens, P.; Zhang, J.; Vargas-Dominguez, S.; DeForest, C. E.; Lamb, D. A.

    2015-12-01

    The solar cycle can be understood as a process that alternates the large-scale magnetic field of the Sun between poloidal and toroidal configurations. Although the process that transitions the solar cycle between toroidal and poloidal phases is still not fully understood, theoretical studies, and observational evidence, suggest that this process is driven by the emergence and decay of bipolar magnetic regions (BMRs) at the photosphere. Furthermore, the emergence of BMRs at the photosphere is the main driver behind solar variability and solar activity in general; making the study of their properties doubly important for heliospheric physics. However, in spite of their critical role, there is still no unified catalog of BMRs spanning multiple instruments and covering the entire period of systematic measurement of the solar magnetic field (i.e. 1975 to present).In this presentation we discuss an ongoing project to address this deficiency by applying our Bipolar Active Region Detection (BARD) code on full disk magnetograms measured by the 512 (1975-1993) and SPMG (1992-2003) instruments at the Kitt Peak Vacuum Telescope (KPVT), SOHO/MDI (1996-2011) and SDO/HMI (2010-present). First we will discuss the results of our revitalization of 512 and SPMG KPVT data, then we will discuss how our BARD code operates, and finally report the results of our cross-callibration.The corrected and improved KPVT magnetograms will be made available through the National Solar Observatory (NSO) and Virtual Solar Observatory (VSO), including updated synoptic maps produced by running the corrected KPVT magnetograms though the SOLIS pipeline. The homogeneous active region database will be made public by the end of 2017 once it has reached a satisfactory level of quality and maturity. The Figure shows all bipolar active regions present in our database (as of Aug 2015) colored according to the sign of their leading polarity. Marker size is indicative of the total active region flux. Anti

  18. A Feasibility Study of CO2-Based Rankine Cycle Powered by Solar Energy

    NASA Astrophysics Data System (ADS)

    Zhang, Xin-Rong; Yamaguchi, Hiroshi; Fujima, Katsumi; Enomoto, Masatoshi; Sawada, Noboru

    An experiment study was carried out in order to investigate feasibility of CO2-based Rankine cycle powered by solar energy. The proposed cycle is to achieve a cogeneration of heat and power, which consists of evacuated solar tube collectors, power generating turbine, heat recovery system, and feed pump. The Rankine cycle of the system utilizes solar collectors to convert CO2 into high-temperature supercritical state, used to drive a turbine and produce electrical power. The cycle also recovers thermal energy, which can be used for absorption refrigerator, air conditioning, hot water supply so on for a building. A set of experimental set-up was constructed to investigate the performance of the CO2-based Rankine cycle. The results show the cycle can achieve production of heat and power with reasonable thermodynamics efficiency and has a great potential of the application of the CO2-based Rankine cycle powered by solar energy. In addition, some research interests related to the present study will also be discussed in this paper.

  19. The Variation of Solar Fe 14 and Fe 10 Flux over 1.5 Solar Activity Cycles

    NASA Technical Reports Server (NTRS)

    Altrock, Richard C.

    1990-01-01

    A new source of data on the solar output, namely limb flux from the one- and two-million degree corona is presented. This parameter is derived from data obtained at the National Solar Observatory at Sacramento Peak with the 40 cm coronagraph of the John W. Evans Solar Facility and the Emission Line Coronal Photometer. The limb flux is defined to be the latitude-averaged intensity in millionths of the brightness of disk center from an annulus of width 1.1 minutes centered at a height of 0.15 solar constant above the limb of emission from lines at 6374A (Fe X) or 5303A (Fe XIV). Fe XIV data have been obtained since 1973 and Fe X since 1984. Examination of the Fe XIV data shows that there is ambiguity in the definition of the last two solar activity minima, which can affect the determination of cycle rise times and lengths. There is an indication that a constant minimum or basal corona may exist at solar minimum. Cycle 22 has had a much faster onset than Cycle 21 and has now overtaken Cycle 21. The rise characteristics of the two cycles were very similar up until Jul. to Aug. 1989, at which time a long-term maximum occurred in Fe X and Fe XIV, which could possibly be the solar maximum. Another maximum is developing at the current time. Cycle 21 was characterized in Fe XIV by at least 4 major thrusts or bursts of activity, each lasting on the order of a year and all having similar maximum limb fluxes which indicates that coronal energy output is sustained over periods in which the sunspot number declines significantly. Dramatic increases in the limb fluxes occur from minimum to maximum, ranging from factors of 14 to 21 in the two lines. Two different techniques to predict the epoch of solar maximum have been applied to the Fe XIV data, resulting in estimates of April 1989 (plus or minus 1 mo) and May 1990 (plus or minus 2 mos).

  20. Cosmic rays, conditions in interplanetary space and geomagnetic variations during solar cycles 19-24

    NASA Astrophysics Data System (ADS)

    Biktash, Lilia

    2016-07-01

    We have studied conditions in interplanetary space, which can have an influence on galactic and solar cosmic rays (CRs). In this connection the solar wind and interplanetary magnetic field parameters and CRs variations have been compared with geomagnetic activity represented by the equatorial Dst and Kp indices beginning from 1955 to the end 2015. The indices are in common practice in the solar wind-magnetosphere-ionosphere interaction studies and they are the final product of this interaction. The important drivers in interplanetary medium which have effect on cosmic rays as CMEs (coronal mass ejections) and CIRs (corotating interaction regions) undergo very strong changes during their propagation to the Earth. Correlation of sunspot numbers and long-term variations of cosmic rays do not adequately reflect peculiarities concerned with the solar wind arrival to 1 AU also. Moreover records of in situ space measurements of the IMF and most other indicators of solar activity cover only a few decades and have a lot of gaps for calculations of long-term variations. Because of this, in such investigations, the geomagnetic indices have some inestimable advantage as continuous series other the solar wind measurements. We have compared the yearly average variations of the indices and of the solar wind parameters with cosmic ray data from Moscow, Climax, Halekala and Oulu neutron monitors during the 20-24 solar cycles. During the descending phases of the solar cycles the long-lasting solar wind high speed streams occurred frequently and were the primary contributors to the recurrent Dst variations and had effects on cosmic rays variations. We show that long-term Dst and Kp variations in these solar cycles were correlated with cosmic ray count rates and can be used for prediction of CR variations. Climate change in connection with evolution of CRs variations is discussed.

  1. Spectral analysis of auroral geomagnetic activity during various solar cycles between 1960 and 2014

    NASA Astrophysics Data System (ADS)

    Kotzé, Pieter Benjamin

    2016-12-01

    In this paper we use wavelets and Lomb-Scargle spectral analysis techniques to investigate the changing pattern of the different harmonics of the 27-day solar rotation period of the AE (auroral electrojet) index during various phases of different solar cycles between 1960 and 2014. Previous investigations have revealed that the solar minimum of cycles 23-24 exhibited strong 13.5- and 9.0-day recurrence in geomagnetic data in comparison to the usual dominant 27.0-day synodic solar rotation period. Daily mean AE indices are utilized to show how several harmonics of the 27-day recurrent period change during every solar cycle subject to a 95 % confidence rule by performing a wavelet analysis of each individual year's AE indices. Results show that particularly during the solar minimum of 23-24 during 2008 the 27-day period is no longer detectable above the 95 % confidence level. During this interval geomagnetic activity is now dominated by the second (13.5-day) and third (9.0-day) harmonics. A Pearson correlation analysis between AE and various spherical harmonic coefficients describing the solar magnetic field during each Carrington rotation period confirms that the solar dynamo has been dominated by an unusual combination of sectorial harmonic structure during 23-24, which can be responsible for the observed anomalously low solar activity. These findings clearly show that, during the unusual low-activity interval of 2008, auroral geomagnetic activity was predominantly driven by high-speed solar wind streams originating from multiple low-latitude coronal holes distributed at regular solar longitude intervals.

  2. Seasonal and solar-cycle variations of DP-type polar magnetic fields resolved via EOF analysis

    NASA Astrophysics Data System (ADS)

    Shore, Robert; Freeman, Mervyn; Wild, James; Dorrian, Gareth; Gjerloev, Jesper

    2016-04-01

    We describe our application of the Empirical Orthogonal Function (EOF) method to characterise and separate contributions to the variability of the Earth's external magnetic field (EMF) in the northern polar region, using ground magnetometer measurements. The EOF method analyses the spatio-temporal co-variance of the data to decompose it into dynamically distinct modes (each mode is a pair of spatial and temporal basis vectors). Briefly, the benefits of this analysis method are firstly that a small number of the modes can cumulatively represent most of the variance of the original data, and secondly that the basis vectors are defined by the data. Hence, the structure of the EMF is resolved compactly without a priori assumptions, in contrast to other decomposition methods such as Fourier and spherical harmonic expansions. We present the modes from 11 years (1997 - 2008) of magnetic vector data at 5 minutes resolution, recently collated by the SuperMAG archive of observatory and variometer data. Despite the sparse and irregular station distribution, a complete spatial morphology of the EMF is achieved using a self-consistent iterative infill method. Using a comparison of the temporal behaviour of the modes alongside independent measures of solar-terrestrial coupling, we demonstrate that the leading three modes describe the well-known Disturbance-Polar currents types 2 and 1 (DP2, DP1) and the system of cusp currents (DPY). These three modes account for the majority of the variance of the data - other modes describe the spatial motions of these current systems. The variation in the DP2, DP1 and DPY currents throughout the last solar cycle is presented, and the utility of this database of magnetic perturbations (to which further analysis methods can be applied) is highlighted.

  3. Solar Wind Sources in the Late Declining Phase of Cycle 23: Effects of the Weak Solar Polar Field on High Speed Streams

    DTIC Science & Technology

    2009-01-01

    solar wind model (Arge and Pizzo, 2000), based on daily updating solar magnetic field synoptic maps, is then used to map the outflows from the corona ...worldwide. University of California Peer Reviewed Title: Solar Wind Sources in the Late Declining Phase of Cycle 23: Effects of the Weak Solar Polar...currently valid OMB control number. 1. REPORT DATE 2009 2. REPORT TYPE 3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Solar Wind

  4. The global August 11, 1999 eclipse corona and solar cycle variations

    NASA Astrophysics Data System (ADS)

    Adjabshirizadeh, Ali; Koutchmy, Serge

    2002-03-01

    Qualitative results from the last solar total eclipse (August 11th, 1999) are presented in order to extract some quantitative parameters permitting to discuss the structure of the near-maximum corona and insert the results among what is known of the changing with the solar cycle of activity structure. The collaborative study of the solar corona has been performed in Iran, using a radial gradient filter in white light and other techniques. From the eclipse-processed pictures, a structural drawing was analysed to give the distribution of streamlines over the entire corona, in order to look at the deviations from the local radial direction of identified coronal streamers. From the deduced parameter and the known solar cycle variations of this instantaneous "average deviation" of coronal streamers, as deduced from eclipse observations of 4 preceding cycles, we correctly predicted the moment of the following maximum of activity. We further discuss the method, using the "average deviations" measured in 1996 - 2001 from the Lasco C2 coronagraph processed images (from NRL) of SoHO and found an excellent agreement with the parameters deduced from the last total eclipses of 1998, 1999 and 2001. We believe that "average deviations" are a good parameter to contribute in the understanding of the origin of solar cycle variations of the solar wind and of the magnetic field.

  5. MAGNETIC FLUX CONSERVATION IN THE HELIOSHEATH INCLUDING SOLAR CYCLE VARIATIONS OF MAGNETIC FIELD INTENSITY

    SciTech Connect

    Michael, A. T.; Opher, M.; Provornikova, E.; Richardson, J. D.; Tóth, G. E-mail: mopher@bu.edu E-mail: jdr@space.mit.edu

    2015-04-10

    In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in magnetic flux. We investigate the role of the 11 yr solar cycle variation of the magnetic field strength on the magnetic flux within the HS using a global 3D magnetohydrodynamic model of the heliosphere. We use time and latitude-dependent solar wind velocity and density inferred from Solar and Heliospheric Observatory/SWAN and interplanetary scintillations data and implemented solar cycle variations of the magnetic field derived from 27 day averages of the field magnitude average of the magnetic field at 1 AU from the OMNI database. With the inclusion of the solar cycle time-dependent magnetic field intensity, the model matches the observed intensity of the magnetic field in the HS along both Voyager 1 and 2. This is a significant improvement from the same model without magnetic field solar cycle variations, which was over a factor of two larger. The model accurately predicts the radial velocity observed by Voyager 2; however, the model predicts a flow speed ∼100 km s{sup −1} larger than that derived from LECP measurements at Voyager 1. In the model, magnetic flux is conserved along both Voyager trajectories, contrary to observations. This implies that the solar cycle variations in solar wind magnetic field observed at 1 AU does not cause the order of magnitude decrease in magnetic flux observed in the Voyager 1 data.

  6. Closed Cycle Engine Program Used in Solar Dynamic Power Testing Effort

    NASA Technical Reports Server (NTRS)

    Ensworth, Clint B., III; McKissock, David B.

    1998-01-01

    NASA Lewis Research Center is testing the world's first integrated solar dynamic power system in a simulated space environment. This system converts solar thermal energy into electrical energy by using a closed-cycle gas turbine and alternator. A NASA-developed analysis code called the Closed Cycle Engine Program (CCEP) has been used for both pretest predictions and post-test analysis of system performance. The solar dynamic power system has a reflective concentrator that focuses solar thermal energy into a cavity receiver. The receiver is a heat exchanger that transfers the thermal power to a working fluid, an inert gas mixture of helium and xenon. The receiver also uses a phase-change material to store the thermal energy so that the system can continue producing power when there is no solar input power, such as when an Earth-orbiting satellite is in eclipse. The system uses a recuperated closed Brayton cycle to convert thermal power to mechanical power. Heated gas from the receiver expands through a turbine that turns an alternator and a compressor. The system also includes a gas cooler and a radiator, which reject waste cycle heat, and a recuperator, a gas-to-gas heat exchanger that improves cycle efficiency by recovering thermal energy.

  7. Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

    2010-01-01

    Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approximately 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

  8. Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum in Microwaves

    NASA Technical Reports Server (NTRS)

    Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

    2011-01-01

    Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radio-heliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

  9. Revisiting the prediction of solar activity based on the relationship between the solar maximum amplitude and max-max cycle length

    NASA Astrophysics Data System (ADS)

    Carrasco, V. M. S.; Vaquero, J. M.; Gallego, M. C.

    2017-01-01

    It is very important to forecast the future solar activity due to its effect on our planet and near space. Here, we employ the new version of the sunspot number index (version 2) to analyse the relationship between the solar maximum amplitude and max-max cycle length proposed by Du (2006). We show that the correlation between the parameters used by Du (2006) for the prediction of the sunspot number (amplitude of the cycle, Rm, and max-max cycle length for two solar cycles before, Pmax-2) disappears when we use solar cycles prior to solar cycle 9. We conclude that the correlation between these parameters depends on the time interval selected. Thus, the proposal of Du (2006) should definitively not be considered for prediction purposes.

  10. Solar Wind Helium Abundance as a Function of Speed and Heliographic Latitude: Variation through a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Kasper, J. C.; Stenens, M. L.; Stevens, M. L.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, Keith W.

    2006-01-01

    We present a study of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind speed and heliographic latitude over the previous solar cycle. The average values of A(sub He), the ratio of helium to hydrogen number densities, are calculated in 25 speed intervals over 27-day Carrington rotations using Faraday Cup observations from the Wind spacecraft between 1995 and 2005. The higher speed and time resolution of this study compared to an earlier work with the Wind observations has led to the discovery of three new aspects of A(sub He), modulation during solar minimum from mid-1995 to mid-1997. First, we find that for solar wind speeds between 350 and 415 km/s, A(sub He), varies with a clear six-month periodicity, with a minimum value at the heliographic equatorial plane and a typical gradient of 0.01 per degree in latitude. For the slow wind this is a 30% effect. We suggest that the latitudinal gradient may be due to an additional dependence of coronal proton flux on coronal field strength or the stability of coronal loops. Second, once the gradient is subtracted, we find that A(sub He), is a remarkably linear function of solar wind speed. Finally, we identify a vanishing speed, at which A(sub He), is zero, is 259 km/s and note that this speed corresponds to the minimum solar wind speed observed at one AU. The vanishing speed may be related to previous theoretical work in which enhancements of coronal helium lead to stagnation of the escaping proton flux. During solar maximum the A(sub He), dependences on speed and latitude disappear, and we interpret this as evidence of two source regions for slow solar wind in the ecliptic plane, one being the solar minimum streamer belt and the other likely being active regions.

  11. The SSRT in the 23rd Cycle of Solar Activity

    NASA Astrophysics Data System (ADS)

    Zandanov, V. G.; Altyntsev, A. T.; Lesovoi, S. V.

    1999-12-01

    We present a sketch of the project to upgrade the Siberian Solar Radio Telescope. We suggest expanding the spectral range of receiving frequencies from a single frequency (5.7~GHz) to five frequencies and to considerably improve the sensitivity of instrument.

  12. QUANTIFYING THE ANISOTROPY AND SOLAR CYCLE DEPENDENCE OF '1/f' SOLAR WIND FLUCTUATIONS OBSERVED BY ADVANCED COMPOSITION EXPLORER

    SciTech Connect

    Nicol, R. M.; Chapman, S. C.; Dendy, R. O.

    2009-10-01

    The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range (IR) of turbulent fluctuations at higher frequencies and a '1/f' like region at lower frequencies. In the ecliptic plane at approx1 AU, this break occurs approximately at timescales of a few hours and is observed in the power spectra of components of velocity and magnetic field. The '1/f' energy range is of more direct coronal origin than the IR, and carries signatures of the complex magnetic field structure of the solar corona, and of footpoint stirring in the solar photosphere. To quantify the scaling properties we use generic statistical methods such as generalized structure functions and probability density functions (PDFs), focusing on solar cycle dependence and on anisotropy with respect to the background magnetic field. We present structure function analysis of magnetic and velocity field fluctuations, using a novel technique to decompose the fluctuations into directions parallel and perpendicular to the mean local background magnetic field. Whilst the magnetic field is close to '1/f', we show that the velocity field is '1/f {sup {alpha}}' with {alpha} {ne} 1. For the velocity, the value of {alpha} varies between parallel and perpendicular fluctuations and with the solar cycle. There is also variation in {alpha} with solar wind speed. We have examined the PDFs in the fast, quiet solar wind and intriguingly, whilst parallel and perpendicular are distinct, both the B field and velocity show the same PDF of their perpendicular fluctuations, which is close to {gamma} or inverse Gumbel. These results point to distinct physical processes in the corona and to their mapping out into the solar wind. The scaling exponents obtained constrain the models for these processes.

  13. Acquired myopia in 11-year-old children.

    PubMed

    Peckham, C S; Gardiner, P A; Goldstein, H

    1977-02-26

    Children who had acquired myopia by the age of 11 years were identified from a nationally representative sample. There were no overall sex differences in its occurrence but myopia was more common in children from non-manual families than in those from manual families. Short-sighted children were more likely to come from small families and to be of higher birth order than children with normal vision, and these associations held within each social class. At 11 years myopic children showed striking advantages in educational performance over their normal-sighted peers, as judged by tests of reading, arithmetic, and general ability. After adjustments had been made for social background, this age gain still amounted to over one year. Findings obtained at 7 years of age showed that superior educational attainments were already apparent before the onset of myopia. Children with myopia read in their leisure time more often than normally sighted children, but despite the visual impairment, they participated in outdoor sports as often as other children.

  14. Solar cycle variation of some mass dependent characteristics of upflowing beams of terrestrial ions

    NASA Technical Reports Server (NTRS)

    Collin, H. L.; Peterson, W. K.; Shelley, E. G.

    1987-01-01

    Examination of the S3-3 and DE ion composition data spread over a solar cycle indicates that some characteristics of energetic upflowing terrestrial ion beams above the auroral zone show dependence on solar cycle. At solar maximum the different ion beam mass components have comparable mean energies, and O(+) dominates the beam composition. The ion energies are consistent with having been acquired from the potential drop below the satellite inferred from the electron loss cone distributions. At solar minimum the beam composition is dominated by H(+), but the O(+) has a higher mean energy and is hotter than the H(+) component. Also, the O(+) has more energy than it could itself have acquired from the potential drop. These observations are qualitatively consistent with the ion beams having acquired their energies from a parallel electric field and being partially thermalized through the two-stream instability between the two ion species, with this effect being modulated by the beam composition.

  15. Equatorial thermospheric wind changes during the solar cycle - Measurements at Arequipa, Peru, from 1983 to 1990

    NASA Technical Reports Server (NTRS)

    Biondi, M. A.; Meriwether, J. W., Jr.; Fejer, B. G.; Gonzalez, S. A.; Hallenbeck, D. C.

    1991-01-01

    Near-equatorial thermospheric wind velocities at Arequipa, Peru, are determined over about two-thirds of a solar cycle using Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line. Mean monthly nocturnal variations in the meridional and zonal wind components are calculated from the nightly data to remove short-term (day-to-day) variability as well as any additional changes introduced by the progression of the solar cycle. For most of the years, at the winter solstice, there is a weak (more than 100 m/s) transequatorial flow from the summer to the winter hemisphere in the early and the late night, with essentially zero velocities in between. At the equinoxes, an early-night poleward (southward) flow at solar minimum (1986) is replaced by an equatorward (northward) flow at solar maximum (1989-1990).

  16. The Waldmeier rule and early diagnostics of the maximum of the current solar cycle

    NASA Astrophysics Data System (ADS)

    Nagovitsyn, Yu. A.; Kuleshova, A. I.

    2012-10-01

    The well known Waldmeier rule and its modifications applied to forecasting of the solar activity are discussed. The maximum annual mean rate of the increase in the magnetic flux observed on the growth branch of the cycle is proposed as a predicting (diagnosing) parameter for the amplitude of the cycle currently in progress. The maximum Wolf number of the current (24th) cycle is estimated to reach 104 (±12) or more, and to occur in 2013 or later. The yearly average Wolf numbers observed during the 24th cycle are presented.

  17. Comparing the Large-Scale Magnetic Field During the Last Three Solar Cycles (Invited)

    NASA Astrophysics Data System (ADS)

    Hoeksema, J. T.

    2009-12-01

    Large-scale magnetic field observations show that the current extended solar cycle minimum differs from the two previous well-observed minima in several respects. The weaker polar fields increase the relative influence of middle and low-latitude flux patterns on the configuration of the corona and heliosphere. A much larger fraction of the open flux originates in equatorial coronal holes. Even though the heliospheric field magnitude and the mean solar magnetic field are the weakest since direct measurements began, the sector structure of the interplanetary field that reflects the shape of the heliospheric current sheet continues to extend to fairly high latitude. The pattern of emergence of active regions through the cycle and the transport of flux from low to high latitudes also show quite different patterns, providing insight into the meridional flow that influences the dynamo that drives the cycle. The long records of synoptic observations that provide a rich source of information about solar activity must be maintained.

  18. Computer modeling of a regenerative solar-assisted Rankine power cycle

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.

    1977-01-01

    A detailed interpretation of the computer program that describes the performance of one of these cycles; namely, a regenerative Rankine power cycle is presented. Water is used as the working medium throughout the cycle. The solar energy collected at relatively low temperature level presents 75 to 80% of the total heat demand and provides mainly the latent heat of vaporization. Another energy source at high temperature level superheats the steam and supplements the solar energy share. A program summary and a numerical example showing the sequency of computations are included. The outcome from the model comprises line temperatures, component heat rates, specific steam consumption, percentage of solar energy contribution, and the overall thermal efficiency.

  19. Coronal mass ejections and solar wind mass fluxes over the heliosphere during solar cycles 23 and 24 (1996-2014)

    NASA Astrophysics Data System (ADS)

    Lamy, P.; Floyd, O.; Quémerais, E.; Boclet, B.; Ferron, S.

    2017-01-01

    Coronal mass ejections (CMEs) play a major role in the heliosphere, and their contribution to the solar wind mass flux, already considered in the Skylab and Solwind eras with conflicting results, is reexamined in the light of 19 years (1996-2014) of SOHO observations with the Large Angle and Spectroscopic Coronagraph (LASCO-C2) for the CMEs and extended for the first time to all latitudes thanks to the whole-heliosphere data from the Solar Wind ANisotropies (SWAN) instrument supplemented by in situ data aggregated in the OMNI database. First, several mass estimates reported in the ARTEMIS (Automated Recognition of Transient Events and Marseille Inventory from Synoptic maps) catalog of LASCO CMEs are compared with determinations based on the combined observations with the twin STEREO/Sun Earth Connection Coronal and Heliospheric Investigation coronagraphs in order to ascertain their validity. A simple geometric model of the CMEs is introduced to generate Carrington maps of their mass flux and then to produce annualized synoptic maps. The Lyman α SWAN data are inverted to similarly produce synoptic maps to be compared with those of the CME flux. The ratio of the annualized CME to solar wind mass flux is found to closely track the solar cycle over the heliosphere. In the near-ecliptic region and at latitudes up to ˜55°, this ratio was negligibly small during the solar minima of cycles 22/23 and 23/24 and rose to 6% and 5%, respectively, at the maximum of solar cycles 23 and 24. These maximum ratios increased at higher latitudes, but this result is likely biased by the inherent limitation of determining the true latitude of CMEs.

  20. The Effect of CMEs on Heliospheric Structure during the Ascending Phase of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Webb, D. F.

    2013-12-01

    The frequency of occurrence of CMEs observed in white light (WL) tends to track the solar cycle in both phase and amplitude, which varies by an order of magnitude over the cycle. Since WL CMEs have been counted since Skylab in the 1970s, we now have observations extending over the last four solar cycles. LASCO has now observed the entire Cycle 23 and continues to observe through the current rise to maximum of Cycle 24. It has detected CMEs at a rate slightly higher than earlier observations, varying from ~0.3/day around solar minimum to ~4/day at maximum. Running averages of the CME rate vs. sunspot number show that both have double cycle peaks, with the CME peak lagging sunspots by many months. This lag is likely related to observations that high latitude CMEs arise from polar crown filaments which have a 'rush to the poles'' near maximum and disappear (erupt) with a frequency that slightly lags sunspot numbers at low latitudes. Cycle 23 had an unusually long decline and flat minimum. Since 2006 we have been able to image and count CMEs in the heliosphere, and can determine rates from both LASCO and STEREO coronagraphs and from the Solar Mass Ejection Imager (SMEI) and the SECCHI Heliospheric Imagers in the heliosphere. Manual rates estimated by observers are now supplemented by counts from identifications made by automatic programs, such as in the SEEDS, CACTus and ARTEMIS catalogs. There is some indication that the CME rate is diverging somewhat from the sunspot number since about 2010. We will discuss these rate estimates, both for the Cycle 23-24 period and over the last four cycles for which we have WL CME observations.

  1. Advances in understanding the genesis and evolution solar energetic particle events over the last two solar cycles

    NASA Astrophysics Data System (ADS)

    Vainio, Rami

    2016-04-01

    I will review the observational and modeling efforts related to solar energetic particle (SEP) events over the 23rd and 24th solar cycles. I will concentrate on large SEP events related to coronal mass ejections (CMEs), but discuss observations related to the possible role of flares in the acceleration of particles in those events, as well. The possible roles of various acceleration and transport processes in understanding the characteristics of the events will be discussed. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA).

  2. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    EPA Science Inventory

    Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

  3. Low Cost Solar Energy Conversion (Carbon Cycle 2.0)

    ScienceCinema

    Ramesh, Ramamoorthy

    2016-07-12

    Ramamoorthy Ramesh from LBNL's Materials Science Division speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

  4. Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

    NASA Astrophysics Data System (ADS)

    Azcárate, T.; Mendoza, B.; Levi, J. R.

    2016-11-01

    We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84 years in Mexico City during the period 2008-2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

  5. Simulation Study of Hemispheric Phase-Asymmetry in the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Shukuya, D.; Kusano, K.

    2017-01-01

    Observations of the Sun suggest that solar activities systematically create north–south hemispheric asymmetries. For instance, the hemisphere in which sunspot activity is more active tends to switch after the early half of each solar cycle. Svalgaard & Kamide recently pointed out that the time gaps of polar field reversal between the northern and southern hemispheres are simply consequences of the asymmetry of sunspot activity. However, the mechanism underlying the asymmetric feature in solar cycle activity is not yet well understood. In this paper, in order to explain the cause of the asymmetry from the theoretical point of view, we investigate the relationship between the dipole- and quadrupole-type components of the magnetic field in the solar cycle using the mean-field theory based on the flux transport dynamo model. As a result, we found that there are two different attractors of the solar cycle, in which either the north or the south polar field is first reversed, and that the flux transport dynamo model explains well the phase-asymmetry of sunspot activity and the polar field reversal without any ad hoc source of asymmetry.

  6. Solar cycle variations of thermospheric O/N2 longitudinal pattern from TIMED/GUVI

    NASA Astrophysics Data System (ADS)

    Luan, Xiaoli; Wang, Wenbin; Burns, Alan; Dou, Xiankang

    2017-02-01

    Thermospheric composition (O/N2 ratio) is well known to have a great impact on the variation of daytime ionospheric electron density. This study aims to investigate the local time, seasonal, and solar cycle variations of the O/N2 longitudinal pattern in both hemispheres during daytime in solstices. The O/N2 data used are from TIMED/Global Ultraviolet Imager observations made over a solar cycle for geomagnetically quiet conditions. The main findings are as follows: (1) The O/N2 longitudinal patterns are generally similar during 10:00-14:00 LT and between solar minimum and maximum, although the O/N2 values change with local time and solar cycle. (2) The winter O/N2 subauroral enhancement is unexpectedly smaller in the longitudes where the magnetic pole is (near-pole longitudes), rather than in the longitudes far from the magnetic pole, especially during solar maximum, and consequently, the longitudinal pattern of O/N2 depends on latitude in local winter. (3) The winter O/N2 subauroral enhancement generally moves to more poleward latitudes during solar maximum, as compared to solar minimum. (4) At higher midlatitudes ( 45°-60°N and 40°-50°S in geographic latitudes) in solar minimum, the winter-to-summer ratio of O/N2 in each hemisphere has an obvious minimum in near-pole longitudes. This minimum becomes more evident during solar maximum. The National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model simulations indicate that in the winter hemisphere, the unexpected O/N2 longitudinal pattern in higher midlatitudes is mainly associated with high-latitude Joule heating under the impact from ion convection and auroral precipitation.

  7. Solar Cycle Variability in Mean Thermospheric Composition and Temperature Induced by Atmospheric Tides

    NASA Astrophysics Data System (ADS)

    Jones, M., Jr.; Forbes, J. M.; Hagan, M. E.

    2015-12-01

    Vertically-propagating atmospheric thermal tides whose origins lie in Earth's lower atmosphere are now widely recognized as one of the dominant "meteorological" drivers of space weather. Many prior research efforts have focused on documenting and understanding the role that dissipating tides play in determining the longitudinal and seasonal variability associated with lower thermospheric winds, temperature, and constituent densities. However, considerably less attention has focused on understanding the potential solar cycle variability in the mean thermospheric state induced by the tides. In this paper we utilize the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), forced with observationally-based tides at the model lower boundary from the Climatological Tidal Model of the Thermosphere (CTMT, from Oberheide et al. [2011]), to elucidate how the dissipating tides induce variations of up to 30 K in the zonal-mean thermosphere temperature between solar minimum and maximum. Numerical experiments are performed for the month of September and for solar minimum, medium, and maximum conditions in order to quantify the solar cycle variability associated with the different terms in the thermodynamic energy, major and minor neutral constituent continuity equations. Our analysis indicates that solar cycle variability in neutral temperatures results from a combination of net eddy heat transport effects and tidal modulation of net nitric oxide (NO) cooling. The chemical and dynamical pathways through which dissipating tides affect mean NO cooling differently at solar minimum and maximum are diagnosed.

  8. 100 W-class solar pumped laser for sustainable magnesium-hydrogen energy cycle

    NASA Astrophysics Data System (ADS)

    Yabe, T.; Bagheri, B.; Ohkubo, T.; Uchida, S.; Yoshida, K.; Funatsu, T.; Oishi, T.; Daito, K.; Ishioka, M.; Yasunaga, N.; Sato, Y.; Baasandash, C.; Okamoto, Y.; Yanagitani, K.

    2008-10-01

    A solar pumped laser system with 7%-9% slope efficiencies has been developed. A Fresnel lens (2×2 m, f =2000 mm) is mounted on a two-axis sun tracker platform and focuses solar radiation toward laser cavity, which embraces Cr:Nd:yttrium aluminum garnet ceramic rod. The maximum emitted laser power is 80 W corresponding to maximum total area performance of 20 W/m2 for the Fresnel lens area. This solar laser system would be used as a section of power plant in a magnesium energy cycle as a cost-efficient solar energy converter. Using direct solar radiation into laser, 4.3% net conversion efficiency has been achieved.

  9. Systems analysis techniques for annual cycle thermal energy storage solar systems

    SciTech Connect

    Baylin, F.; Sillman, S.

    1980-07-01

    Community-scale annual cycle thermal energy storage (ACTES) solar systems are promising options for building heat and cooling. A variety of approaches are feasible in modeling ACTES solar systems. The key parameter in such efforts, average collector efficiency, is first examined, followed by several approaches for simple and effective modeling. Methods are also examined for modeling building loads for structures based on both conventional and passive architectural designs. Two simulation models for sizing solar heating systems with annual storage are presented next. Validation is presented by comparison with the results of a study of seasonal storage systems based on SOLANSIM, an hour-by-hour simulation. These models are presently being used to examine the economic trade-off between collector field area and storage capacity. Finally, programs in the US Department of Energy directed toward developing either other system components such as improved tanks and solar ponds or design tools for ACTES solar systems are examined.

  10. THE ACOUSTIC CUTOFF FREQUENCY OF THE SUN AND THE SOLAR MAGNETIC ACTIVITY CYCLE

    SciTech Connect

    Jimenez, A.; Palle, P. L.; Garcia, R. A.

    2011-12-20

    The acoustic cutoff frequency-the highest frequency for acoustic solar eigenmodes-is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but are traveling waves. Interference among them gives rise to higher-frequency peaks-the pseudomodes-in the solar acoustic spectrum. The pseudomodes are shifted slightly in frequency with respect to p-modes, making possible the use of pseudomodes to determine the acoustic cutoff frequency. Using data from the GOLF and VIRGO instruments on board the Solar and Heliospheric Observatory spacecraft, we calculate the acoustic cutoff frequency using the coherence function between both the velocity and intensity sets of data. By using data gathered by these instruments during the entire lifetime of the mission (1996 until the present), a variation in the acoustic cutoff frequency with the solar magnetic activity cycle is found.

  11. On the changes with solar cycles of cosmic ray propagation parameters and dimension of modulation region and heliosphere

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.

    We continue our investigations of cosmic ray-solar activity hysteresis phenomenon by using data of Climax and Huancayo/Haleakala neutron monitors and Huancayo ionization chamber for about 4 solar cycles. We determine approximately the changes from one cycle to another of the effective dimension of modulation region and Heliosphere and show that there is a great difference between even and odd solar cycles, and appreciable dependence on the effective rigidity of cosmic ray particles for even cycles. It appears that there are at least 3 cycles in cosmic ray modulation: 11, 22 and 44 years.

  12. Dynamics of the photosphere along the solar cycle from SDO/HMI

    NASA Astrophysics Data System (ADS)

    Roudier, Th.; Malherbe, J. M.; Mirouh, G. M.

    2017-02-01

    Context. As the global magnetic field of the Sun has an activity cycle, one expects to observe some variation of the dynamical properties of the flows visible in the photosphere. Aims: We investigate the flow field during the solar cycle by analysing SDO/HMI observations of continuum intensity, Doppler velocity and longitudinal magnetic field. Methods: We first picked data at disk center during 6 yr along the solar cycle with a 48-h time step in order to study the overall evolution of the continuum intensity and magnetic field. Then we focused on thirty 6-h sequences of quiet regions without any remnant of magnetic activity separated by 6 months, in summer and winter, when disk center latitude B0 is close to zero. The horizontal velocity was derived from the local correlation tracking technique over a field of view of 216.4 Mm × 216.4 Mm located at disk center. Results: Our measurements at disk center show the stability of the flow properties between meso- and supergranular scales along the solar cycle. Conclusions: The network magnetic field, produced locally at disk center independently from large scale dynamo, together with continuum contrast, vertical and horizontal flows, seem to remain constant during the solar cycle.

  13. H-alpha synoptic charts of solar activity during the first year of solar cycle 20, October 1964 - August 1965. [Skylab program

    NASA Technical Reports Server (NTRS)

    Mcintosh, P. S.

    1975-01-01

    Solar activity during the period October 28, 1964 through August 27, 1965 is presented in the form of charts for each solar rotation constructed from observations made with the chromospheric H-alpha spectra line. These H-alpha synoptic charts are identical in format and method of construction to those published for the period of Skylab observations. The sunspot minimum marking the start of Solar Cycle 20 occurred in October, 1964; therefore, charts represent solar activity during the first year of this solar cycle.

  14. Life Cycle Assessment of Titania Perovskite Solar Cell Technology for Sustainable Design and Manufacturing.

    PubMed

    Zhang, Jingyi; Gao, Xianfeng; Deng, Yelin; Li, Bingbing; Yuan, Chris

    2015-11-01

    Perovskite solar cells have attracted enormous attention in recent years due to their low cost and superior technical performance. However, the use of toxic metals, such as lead, in the perovskite dye and toxic chemicals in perovskite solar cell manufacturing causes grave concerns for its environmental performance. To understand and facilitate the sustainable development of perovskite solar cell technology from its design to manufacturing, a comprehensive environmental impact assessment has been conducted on titanium dioxide nanotube based perovskite solar cells by using an attributional life cycle assessment approach, from cradle to gate, with manufacturing data from our laboratory-scale experiments and upstream data collected from professional databases and the literature. The results indicate that the perovskite dye is the primary source of environmental impact, associated with 64.77% total embodied energy and 31.38% embodied materials consumption, contributing to more than 50% of the life cycle impact in almost all impact categories, although lead used in the perovskite dye only contributes to about 1.14% of the human toxicity potential. A comparison of perovskite solar cells with commercial silicon and cadmium-tellurium solar cells reveals that perovskite solar cells could be a promising alternative technology for future large-scale industrial applications.

  15. Solar Cycle Variation and Application to the Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Kim, Myung-Hee Y.; Shinn, Judy L.; Tai, Hsiang; Cucinotta, Francis A.; Badhwar, Gautam D.; Badavi, Francis F.; Atwell, William

    1999-01-01

    The interplanetary plasma and fields are affected by the degree of disturbance that is related to the number and types of sunspots in the solar surface. Sunspot observations were improved with the introduction of the telescope in the seventeenth century, allowing observations which cover many centuries. A single quantity (sunspot number) was defined by Wolf in 1848 that is now known to be well correlated with many space observable quantities and is used herein to represent variations caused in the space radiation environment. The resultant environmental models are intended for future aircraft and space-travel-related exposure estimates.

  16. Solar Cycle Effects on the Near-Earth Space Systems

    DTIC Science & Technology

    1990-08-06

    existence of cyclic behavior extend as far back as the invention of the telescope in tne 17th century (see Galilei , 1957). Perhaps the earliest...of Cosmic Ray Intensity on November 19, 1949," Physical Review 79, 501 (1950). G. Galilei , "Letters on Sunspots, 1612," in Discoveries and Opinions of... Galileo , pp. 106-119, Doubleday and Company, Inc., New York (1957). 61 H. B. Garrett, H. B., Dessler, A. J., and T. W. Hill, "Influence of Solar

  17. Oscillating dynamo in the presence of a fossil magnetic field - The solar cycle

    NASA Technical Reports Server (NTRS)

    Levy, E. H.; Boyer, D.

    1982-01-01

    Hydromagnetic dynamo generation of oscillating magnetic fields in the presence of an external, ambient magnetic field introduces a marked polarity asymmetry between the two halves of the magnetic cycle. The principle of oscillating dynamo interaction with external fields is developed, and a tentative application to the sun is described. In the sun a dipole moment associated with the stable fluid beneath the convection zone would produce an asymmetrical solar cycle.

  18. DISTRIBUTION OF MAGNETIC BIPOLES ON THE SUN OVER THREE SOLAR CYCLES

    SciTech Connect

    Tlatov, Andrey G.; Vasil'eva, Valerya V.; Pevtsov, Alexei A. E-mail: apevtsov@nso.ed

    2010-07-01

    We employ synoptic full disk longitudinal magnetograms to study latitudinal distribution and orientation (tilt) of magnetic bipoles in the course of sunspot activity during cycles 21, 22, and 23. The data set includes daily observations from the National Solar Observatory at Kitt Peak (1975-2002) and Michelson Doppler Imager on board the Solar and Heliospheric Observatory (MDI/SOHO, 1996-2009). Bipole pairs were selected on the basis of proximity and flux balance of two neighboring flux elements of opposite polarity. Using the area of the bipoles, we have separated them into small quiet-Sun bipoles (QSBs), ephemeral regions (ERs), and active regions (ARs). We find that in their orientation, ERs and ARs follow Hale-Nicholson polarity rule. As expected, AR tilts follow Joy's law. ERs, however, show significantly larger tilts of opposite sign for a given hemisphere. QSBs are randomly oriented. Unlike ARs, ERs also show a preference in their orientation depending on the polarity of the large-scale magnetic field. These orientation properties may indicate that some ERs may form at or near the photosphere via the random encounter of opposite polarity elements, while others may originate in the convection zone at about the same location as ARs. The combined latitudinal distribution of ERs and ARs exhibits a clear presence of Spoerer's butterfly diagram (equatorward drift in the course of a solar cycle). ERs extend the ARs' 'wing' of the butterfly diagram to higher latitudes. This high latitude extension of ERs suggests an extended solar cycle with the first magnetic elements of the next cycle developing shortly after the maximum of the previous cycle. The polarity orientation and tilt of ERs may suggest the presence of poloidal fields of two configurations (new cycle and old cycle) in the convection zone at the declining phase of the sunspot cycle.

  19. SOLAR MAGNETIC ACTIVITY CYCLES, CORONAL POTENTIAL FIELD MODELS AND ERUPTION RATES

    SciTech Connect

    Petrie, G. J. D.

    2013-05-10

    We study the evolution of the observed photospheric magnetic field and the modeled global coronal magnetic field during the past 3 1/2 solar activity cycles observed since the mid-1970s. We use synoptic magnetograms and extrapolated potential-field models based on longitudinal full-disk photospheric magnetograms from the National Solar Observatory's three magnetographs at Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun vector spectro-magnetograph, the spectro-magnetograph and the 512-channel magnetograph instruments, and from Stanford University's Wilcox Solar Observatory. The associated multipole field components are used to study the dominant length scales and symmetries of the coronal field. Polar field changes are found to be well correlated with active fields over most of the period studied, except between 2003 and 2006 when the active fields did not produce significant polar field changes. Of the axisymmetric multipoles, only the dipole and octupole follow the poles whereas the higher orders follow the activity cycle. All non-axisymmetric multipole strengths are well correlated with the activity cycle. The tilt of the solar dipole is therefore almost entirely due to active-region fields. The axial dipole and octupole are the largest contributors to the global field except while the polar fields are reversing. This influence of the polar fields extends to modulating eruption rates. According to the Computer Aided CME Tracking, Solar Eruptive Event Detection System, and Nobeyama radioheliograph prominence eruption catalogs, the rate of solar eruptions is found to be systematically higher for active years between 2003 and 2012 than for those between 1997 and 2002. This behavior appears to be connected with the weakness of the late-cycle 23 polar fields as suggested by Luhmann. We see evidence that the process of cycle 24 field reversal is well advanced at both poles.

  20. Solar cycle dependence in the statistical and correlation properties of geomagnetic indices and the solar wind driver

    NASA Astrophysics Data System (ADS)

    Chapman, Sandra

    2010-05-01

    Scaling and a departure from Gaussian statistics has been identified as a key property of magnetospheric energy release as seen in geomagnetic indices derived from ground based magnetometer observations. These long timeseries can be readily compared with those of in- situ observations from spacecraft that monitor the solar wind driver. We will compare quantitative evidence of correlation, scaling and departures from Gaussian statistics in the fluctuations in the solar wind, with that seen in geomagnetic indices AU and AL and in the epsilon parameter that characterizes energy inflow and driving of the magnetosphere by the solar wind. On timescales shorter than the characteristic substorm timescale, fluctuations in the indices show a characteristic power law power spectrum and scaling in their non- Gaussian probability density functionss. Dividing the data into intervals of solar maximum and minimum reveals that whereas fluctuations in epsilon and AU change their properties with the solar cycle, fluctuations in AL do not. These quantitative statistical measures place strong statistical constraints on the propagation of information from these below- substorm scale fluctuations from the solar wind to the magnetosphere as seen by the indices. Scaling of fractal type also offers the possibility of (nonlinear, or fractional stochastic differential equations) Fokker- Planck models (analogous to Black-Scholes type models for stock and option price dynamics) for these timeseries which we will discuss. Direct nonlinear measures of correlation such as Mutual Information (MI) can also be used to characterize the driving of the geomagnetic indices by the solar wind. We discuss how MI can be used to identify the optimal solar wind driving parameter in a model independent manner.

  1. The Influence of the Solar Cycle on Plasmasphere Refilling

    NASA Astrophysics Data System (ADS)

    Krall, J.; Huba, J.

    2015-12-01

    During refilling, ionospheric plasma streams into the inner magnetosphere from both the northern and southern hemispheres. Plasmasphere refilling rates depend on both the ionospheric sources and on the thermalization of streaming ions. We use the NRL SAMI3 ionosphere/plasmasphere code[1] coupled to the NRLMSIS empirical atmosphere model and the HWM14 empirical wind model, to simulate H+, He+ and O+ populations in the plasmasphere. The SAMI3 ionosphere code includes 7 ion species (H+, He+, O+, N+, O2+, N2+, NO+), each treated as a separate fluid, with temperature equations being solved for H+, He+, O+ and e. Measurements show that refilling rates decrease with increasing solar activity, an effect reproduced by SAMI3 and its two-dimensional cousin, SAMI2. We find that the refilling rate and the resulting the plasmasphere electron content are sensitive to the thermospheric composition and temperature, as well as photoelectron heating and photoproduction rates. Depending on conditions, simulations suggest that the plasmaspheric contribution to the total electron content can either increase or decrease with solar activity, as represented by the daily and 81-day-average F10.7 indices. [1] Huba, J. and J. Krall, 2013, ``Modeling the plasmasphere with SAMI3'', Geophys. Res. Lett. 40, 6--10, doi:10.1029/2012GL054300 Research supported by NRL base funds and the NASA HSR program.

  2. Effects of meridional flow variations on solar cycles 23 and 24

    SciTech Connect

    Upton, Lisa; Hathaway, David H. E-mail: lar0009@uah.edu

    2014-09-10

    The faster meridional flow that preceded the solar cycle 23/24 minimum is thought to have led to weaker polar field strengths, producing the extended solar minimum and the unusually weak cycle 24. To determine the impact of meridional flow variations on the sunspot cycle, we have simulated the Sun's surface magnetic field evolution with our newly developed surface flux transport model. We investigate three different cases: a constant average meridional flow, the observed time-varying meridional flow, and a time-varying meridional flow in which the observed variations from the average have been doubled. Comparison of these simulations shows that the variations in the meridional flow over cycle 23 have a significant impact (∼20%) on the polar fields. However, the variations produced polar fields that were stronger than they would have been otherwise. We propose that the primary cause of the extended cycle 23/24 minimum and weak cycle 24 was the weakness of cycle 23 itself—with fewer sunspots, there was insufficient flux to build a big cycle. We also find that any polar counter-cells in the meridional flow (equatorward flow at high latitudes) produce flux concentrations at mid-to-high latitudes that are not consistent with observations.

  3. An Observed Decline in the Amplitude of Recent Solar-Cycle Peaks

    NASA Astrophysics Data System (ADS)

    Chapman, G. A.; de Toma, G.; Cookson, A. M.

    2014-10-01

    There has been much speculation about the extended minimum between Solar Cycles 23 and 24. Cycle 24 itself has been unusually weak compared with recent cycles. We present quantitative evidence for the weakness of both Cycles 23 and, particularly, 24. The data are objective indices derived from precision photometric images obtained on a daily basis at the San Fernando Observatory. These data form the longest running, homogeneous photometric record known to us. We show sunspot areas from red images and facular/network areas from Ca ii K-line images. Spot and facular area are a simple and direct measurement of the strength of solar activity. The data clearly show the decline in the amplitude of sunspot maxima for Cycles 23 and 24 compared with Cycle 22. The relative amplitudes of mean spot area for Cycles 22 through 24 are 1.0, 0.74, and 0.37, respectively. There is also an indication that the facular-to-spot area ratio has increased in Cycle 24.

  4. The variability of coronal holes during two last cycles of solar activity

    NASA Astrophysics Data System (ADS)

    Prosovetsky, Dmitry

    Coronal holes (CH) well known as open magnetic field area are the important factor of space weather variability and geomagnetic disturbances in the Earth's magnetosphere. The properties of CH as well as related with them high-speed solar wind streams are defined by features of a configuration of a magnetic field and an atmosphere structure above. However, till now it is not clear, how these parameters vary during different cycles of solar activity and different phases of cycle development. In this paper the comparative examination of CH properties is carried out for minima of 22 and 23 cycles of solar activity. The observations data of UV and microwave emission at four frequencies together with measuring of a magnetic field and its extrapolation on high levels were studied. Some significant features were founded. It was noticed the middle-latitude and equatorial CH with largest area exists during large time of a cycle with an identical configuration of a large-scale magnetic field. CH of an identical configuration (e.g. elephant trunk) are observed in both various cycles of solar activity that reflects identical mechanisms of a global magnetic field formation in a cycle. Brightness temperatures at levels of chromosphere and the low corona in a CH of a cycle 23 minimum, on the average, are 50 percents less than temperature during cycle 22 minimum. It is found, that the large-scale magnetic field of the Sun in activity minimums is segmented by alternating areas of different polarity, and the magnetic fields of CH are one of segments. In cycle 22 minimum the meridional segments of the magnetic field related with CH were dominated. On the other hand during 23 cycle the latitudinal segments were dominated. Features of CH with the closed configuration of a magnetic field perhaps not are visible in UV and microwave emission. Visibility requirements of CH as dark features in UV concerning the quiet Sun are quasi-radiality of a magnetic field and its value ¿5 Gs were

  5. Expected Radiation Hazard at Different Phases of Solar Cycle Based on Statistical Properties of Solar Energetic Particle Fluencies

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Pustil'Nik, L.

    2008-09-01

    Expected radiation hazard from SEP (Solar Energetic Particle) events for space probes in interplanetary space at different distances from the Sun, for satellites in magnetosphere of the Earth on different orbits, for planes on different airlines, and on people and technology on the ground on different altitudes and cutoff rigidities is determined mostly by expected fluency (total flux of SEP during solar flare event) in different energy ranges at different phases of solar cycle. Information on expected total radiation hazard from SEP events (as well as from galactic cosmic ray (CR)) in different phases of solar cycle is necessary for estimation of optimal shielding of electronics and/or people both in space (on satellites at different orbits, on interplanetary missions, and on ISS ¿ International Space Station) as well as in atmosphere (for aircrafts at different altitudes and technology objects and people on the ground level). We estimated probabilities of fluencies on the basis of long time observation of proton flux (both direct measurements on the space detectors and on the base of recalculation from ground stations). Restored amplitude spectrum (distribution of events with given interval of amplitudes of the fluency or for fluencies more than given) enables us estimate probability of dangerous states and extrapolate this distribution for rare events of extremely high amplitudes. Main sources of data for this analysis are: 1) data from the Catalog "A Summary of Major Solar Proton Events" (Shea and Smart, Solar Phys., 1990) for 31 years observations fluencies on the ground and in space, 2) for detailed analysis - data from satellites GOES during 1994-2004, available through Internet.

  6. The effect of solar activity on the evolution of solar wind parameters during the rise of the 24th cycle

    NASA Astrophysics Data System (ADS)

    Rod'kin, D. G.; Shugay, Yu. S.; Slemzin, V. A.; Veselovskii, I. S.

    2016-01-01

    The dynamics of parameters of the near-Earth solar wind (SW) and the effect of solar activity on the parameters of three SW components (fast SW from large-scale coronal holes (CHs); slow SW from active regions, streamers, and other sources; and transient flows related to sporadic solar activity) at the beginning of the 24th solar cycle (2009-2011) are analyzed. It is demonstrated that temperaturedependent parameters of ionic composition (C+6/C+5 and O+7/O+6) of the transient SW component in the profound minimum of solar activity in 2009 were correlated with the variation of the rate of weak (type C and weaker) flares. This verifies the presence of a hot component associated with these flares in the SW. The variations in the velocity and the kinetic temperature of fast SW from CHs with an increase in activity are more pronounced in the bulk of the high-speed stream, and the variations of O+7/O+6 and Fe/O ratios and the magnitude of the interplanetary magnetic field are the most prominent in the region of interaction between fast and slow SW streams. The analysis reveals that a value of O+7/O+6 = 0.1 serves as the criterion to distinguish between fast SW streams and interplanetary coronal mass ejections in the 2009 activity minimum. This value is lower than the one (0.145) determined earlier based on the data on the 23rd cycle (Zhao et al., 2009). Therefore, the distinguishing criterion is not an absolute one and depends on the solar activity level.

  7. Comparison of Total Solar Irradiance with NASA/NSO Spectromagnetograph Data in Solar Cycles 22 and 23

    NASA Technical Reports Server (NTRS)

    Jones, Harrison P.; Branston, Detrick D.; Jones, Patricia B.; Popescu, Miruna D.

    2002-01-01

    An earlier study compared NASA/NSO Spectromagnetograph (SPM) data with spacecraft measurements of total solar irradiance (TSI) variations over a 1.5 year period in the declining phase of solar cycle 22. This paper extends the analysis to an eight-year period which also spans the rising and early maximum phases of cycle 23. The conclusions of the earlier work appear to be robust: three factors (sunspots, strong unipolar regions, and strong mixed polarity regions) describe most of the variation in the SPM record, but only the first two are associated with TSI. Additionally, the residuals of a linear multiple regression of TSI against SPM observations over the entire eight-year period show an unexplained, increasing, linear time variation with a rate of about 0.05 W m(exp -2) per year. Separate regressions for the periods before and after 1996 January 01 show no unexplained trends but differ substantially in regression parameters. This behavior may reflect a solar source of TSI variations beyond sunspots and faculae but more plausibly results from uncompensated non-solar effects in one or both of the TSI and SPM data sets.

  8. Solar Fuels and Carbon Cycle 2.0 (Carbon Cycle 2.0)

    ScienceCinema

    Alivisatos, Paul

    2016-07-12

    Paul Alivisatos, LBNL Director speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 4, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

  9. Synchronized Northern Hemisphere climate change and solar magnetic cycles during the Maunder Minimum

    PubMed Central

    Yamaguchi, Yasuhiko T.; Yokoyama, Yusuke; Miyahara, Hiroko; Sho, Kenjiro; Nakatsuka, Takeshi

    2010-01-01

    The Maunder Minimum (A.D. 1645–1715) is a useful period to investigate possible sun–climate linkages as sunspots became exceedingly rare and the characteristics of solar cycles were different from those of today. Here, we report annual variations in the oxygen isotopic composition (δ18O) of tree-ring cellulose in central Japan during the Maunder Minimum. We were able to explore possible sun–climate connections through high-temporal resolution solar activity (radiocarbon contents; Δ14C) and climate (δ18O) isotope records derived from annual tree rings. The tree-ring δ18O record in Japan shows distinct negative δ18O spikes (wetter rainy seasons) coinciding with rapid cooling in Greenland and with decreases in Northern Hemisphere mean temperature at around minima of decadal solar cycles. We have determined that the climate signals in all three records strongly correlate with changes in the polarity of solar dipole magnetic field, suggesting a causal link to galactic cosmic rays (GCRs). These findings are further supported by a comparison between the interannual patterns of tree-ring δ18O record and the GCR flux reconstructed by an ice-core 10Be record. Therefore, the variation of GCR flux associated with the multidecadal cycles of solar magnetic field seem to be causally related to the significant and widespread climate changes at least during the Maunder Minimum. PMID:21076031

  10. Conceptual design and techno-economic assessment of integrated solar combined cycle system with DSG technology

    SciTech Connect

    Nezammahalleh, H.; Farhadi, F.; Tanhaemami, M.

    2010-09-15

    Direct steam generation (DSG) in parabolic trough collectors causes an increase to competitiveness of solar thermal power plants (STPP) by substitution of oil with direct steam generation that results in lower investment and operating costs. In this study the integrated solar combined cycle system with DSG technology is introduced and techno-economic assessment of this plant is reported compared with two conventional cases. Three considered cases are: an integrated solar combined cycle system with DSG technology (ISCCS-DSG), a solar electric generating system (SEGS), and an integrated solar combined cycle system with HTF (heat transfer fluid) technology (ISCCS-HTF). This study shows that levelized energy cost (LEC) for the ISCCS-DSG is lower than the two other cases due to reducing O and M costs and also due to increasing the heat to electricity net efficiency of the power plant. Among the three STPPs, SEGS has the lowest CO{sub 2} emissions, but it will operate during daytime only. (author)

  11. Magnetohydrodynamic Simulation-driven Kinematic Mean Field Model of the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Simard, Corinne; Charbonneau, Paul; Bouchat, Amélie

    2013-05-01

    We construct a series of kinematic axisymmetric mean-field dynamo models operating in the αΩ, α2Ω and α2 regimes, all using the full α-tensor extracted from a global magnetohydrodynamical simulation of solar convection producing large-scale magnetic fields undergoing solar-like cyclic polarity reversals. We also include an internal differential rotation profile produced in a purely hydrodynamical parent simulation of solar convection, and a simple meridional flow profile described by a single cell per meridional quadrant. An α2Ω mean-field model, presumably closest to the mode of dynamo action characterizing the MHD simulation, produces a spatiotemporal evolution of magnetic fields that share some striking similarities with the zonally-averaged toroidal component extracted from the simulation. Comparison with α2 and αΩ mean-field models operating in the same parameter regimes indicates that much of the complexity observed in the spatiotemporal evolution of the large-scale magnetic field in the simulation can be traced to the turbulent electromotive force. Oscillating α2 solutions are readily produced, and show some similarities with the observed solar cycle, including a deep-seated toroidal component concentrated at low latitudes and migrating equatorward in the course of the solar cycle. Various numerical experiments performed using the mean-field models reveal that turbulent pumping plays an important role in setting the global characteristics of the magnetic cycles.

  12. MAGNETOHYDRODYNAMIC SIMULATION-DRIVEN KINEMATIC MEAN FIELD MODEL OF THE SOLAR CYCLE

    SciTech Connect

    Simard, Corinne; Charbonneau, Paul; Bouchat, Amelie E-mail: paulchar@astro.umontreal.ca

    2013-05-01

    We construct a series of kinematic axisymmetric mean-field dynamo models operating in the {alpha}{Omega}, {alpha}{sup 2}{Omega} and {alpha}{sup 2} regimes, all using the full {alpha}-tensor extracted from a global magnetohydrodynamical simulation of solar convection producing large-scale magnetic fields undergoing solar-like cyclic polarity reversals. We also include an internal differential rotation profile produced in a purely hydrodynamical parent simulation of solar convection, and a simple meridional flow profile described by a single cell per meridional quadrant. An {alpha}{sup 2}{Omega} mean-field model, presumably closest to the mode of dynamo action characterizing the MHD simulation, produces a spatiotemporal evolution of magnetic fields that share some striking similarities with the zonally-averaged toroidal component extracted from the simulation. Comparison with {alpha}{sup 2} and {alpha}{Omega} mean-field models operating in the same parameter regimes indicates that much of the complexity observed in the spatiotemporal evolution of the large-scale magnetic field in the simulation can be traced to the turbulent electromotive force. Oscillating {alpha}{sup 2} solutions are readily produced, and show some similarities with the observed solar cycle, including a deep-seated toroidal component concentrated at low latitudes and migrating equatorward in the course of the solar cycle. Various numerical experiments performed using the mean-field models reveal that turbulent pumping plays an important role in setting the global characteristics of the magnetic cycles.

  13. Chaos and periodicity in solar wind speed: cycle 23

    NASA Astrophysics Data System (ADS)

    Sarkar, Tushnik; Ray, Rajdeep; Khondekar, Mofazzal H.; Ghosh, Koushik; Banerjee, Subrata

    2015-06-01

    The solar wind speed time series data from 1st January, 1997 to 28th October, 2003 has been pre-processed using simple exponential smoothing, discrete wavelet transform for denoising to investigate the underneath dynamics of it. Recurrence plot and recurrence quantification analysis has revealed that the time series is non-stationary one with deterministic chaotic behavior. The Hilbert-Huang Transform has been used in search of the underlying periods of the data series. Present investigation has revealed the periods of 21 days, 32.5 days, 43.6 days, 148.86 days, 180.7 days, 355.5 days, 403.2 days, 413.6 days, 490.72 days, 729.6 days, 1086.76 days, 1599.4 days and 1892.6 days.

  14. Solar-Cycle Changes in GONG P-Mode Widths and Amplitudes 1995-1998

    NASA Technical Reports Server (NTRS)

    Komm R. W.; Howe, R.; Hill, F.

    1999-01-01

    We search for a solar cycle variation in mode widths and amplitudes derived from 3-month GONG time series. The variation of mode width and amplitude observed in GONG data are the combined effects of fill factor, temporal variation, and measurement uncertainties. The largest variation is caused by the fill factor resulting in modes with increased width and reduced amplitude when fill is lower. We assume that the solar cycle variation is the only other systematic variation beside the temporal window function effect. We correct all currently available data sets for the fill factor and simultaneously derive the solar cycle variation. We find an increase of about 3% on average in mode width from the previous minimum to Oct. 1998 and a decrease of about 7% and 6% in mode amplitude and mode area (width x amplitude). We find no l dependence of the solar-cycle changes. As a function of frequency, these changes show a maximum between 2.7 and 3.3 mHz with about 47% higher than average values for mode width and about 29% and 36% higher ones for mode amplitude and area. We estimate the significance of these rather small changes by a pre-whitening method and find that the results are significant at or above the 99.9% level with mode area showing the highest level of significance and mode width the lowest. The variation in background amplitude is most likely not significant and is consistent with a zero change.

  15. Occurrence rate of SAR arcs during the 23nd solar activity cycle

    NASA Astrophysics Data System (ADS)

    Ievenko, Igor

    By data of photometric observations at the Maimaga station (57° N, 200° E, geomagnetic coordinates) at the Yakutsk meridian the occurrence rate of subauroral red (SAR) arcs for the 1997 to 2006 period has been analysed. The observations were carried out during winterspring periods at moonless nights under favorable atmospheric conditions. For˜370 nights of observations (total duration is˜3170 hours) 114 cases of SAR arcs occurrence (˜500 hours) have been registered. The occurrence rate of SAR arcs have been determined as a ratio of the number of registration hour intervals of SAR arcs to the summary observation time in hours for particular months. Subauroral red arcs have been registered every year both in the maximum and in the minimum of the solar activity cycle. The most observation occurrence of red arcs is registered on the rise (˜27%) and decay of the maximum of the solar activity cycle (˜36%). The average occurrence rate of SAR arcs during these years was less than in the 22nd solar activity cycle and is equal to ˜16% of the total observation time. The occurrence rate of SAR arcs observations corresponds to the changes of geomagnetic activity during the 23nd solar activity cycle.

  16. SOLAR ULTRAVIOLET RADIATION AND AQUATIC CARBON, NITROGEN, SULFUR AND METALS CYCLES

    EPA Science Inventory

    Solar ultraviolet radiation (290-400 nm) has a wide-ranging impact on biological and chemical processes that affect the cycling of elements in aquatic environments. This chapter uses recent field and laboratory observations along with models to assess these impacts on carbon, nit...

  17. Formation of the equatorial thermosphere anomaly trough: Local time and solar cycle variations

    NASA Astrophysics Data System (ADS)

    Hsu, Vicki W.; Thayer, Jeffrey P.; Lei, Jiuhou; Wang, Wenbin

    2014-12-01

    This paper evaluates the formation and behavior of the equatorial thermosphere anomaly (ETA) trough in neutral temperature and mass density using the National Center for Atmospheric Research thermosphere-ionosphere electrodynamics general circulation model under quiet geomagnetic activity and March equinox conditions. The driving mechanism for the generation of the ETA trough in the model is field-aligned ion drag. In our simulations, during the daytime, field-aligned ion drag on the north-south flanks of the magnetic equator causes a divergence in meridional winds, leading to an upward change in vertical winds, adiabatic cooling, and a reduction in neutral temperature of about 30 K over the magnetic equator near 400 km. This response closely links ETA behavior to variations in the equatorial ionosphere anomaly (EIA) associated with local time and solar cycle. As the EIA begins to disappear in the evening, the processes in the ETA mechanism recede, causing the ETA trough to subside. The ETA trough is not completely eliminated until about after 23:00 LT. In our simulations, the trough becomes more prominent as the solar cycle progresses from low (F10.7=80) to high (F10.7=180), in agreement with observations. The neutral-ion collision frequency (proportional to variations in electron density) controls ETA day-to-night and solar cycle variations, while plasma scale height and gradients in electron number density and plasma temperature produce a secondary structure in ETA local time behavior that varies with solar cycle levels.

  18. A Brayton cycle solar dynamic heat receiver for space

    NASA Technical Reports Server (NTRS)

    Sedgwick, L. M.; Nordwall, H. L.; Kaufmann, K. J.; Johnson, S. D.

    1989-01-01

    The detailed design of a heat receiver developed to meet the requirements of the Space Station Freedom, which will be assembled and operated in low earth orbit beginning in the mid-1990's, is described. The heat receiver supplies thermal energy to a nominal 25-kW closed-Brayton-cycle power conversion unit. The receiver employs an integral thermal energy storage system utilizing the latent heat of a eutectic-salt phase-change mixture to store energy for eclipse operation. The salt is contained within a felt metal matrix which enhances heat transfer and controls the salt void distribution during solidification.

  19. Solar dynamic organic Rankine cycle heat rejection system simulation

    NASA Technical Reports Server (NTRS)

    Havens, V. N.; Ragaller, D. R.; Namkoong, D.

    1987-01-01

    The use of a rotary fluid management device (RFMD) and shear flow condenser for two-phase fluid management in microgravity organic Rankine cycle (ORC) applications is examined. A prototype of the proposed Space Station ORC heat rejection system was constructed to evaluate the performance of the inventory control method. The design and operation of the RFMD, shear flow condenser, and inventory control fluid accumulator are described. A schematic diagram of the ORC, RFMD, and condenser, and a functional diagram of the heat rejection system for the ORC are presented.

  20. Solar Cycle Variations in Polar Cap Area Measured by the SuperDARN Radars

    NASA Astrophysics Data System (ADS)

    Imber, S. M.; Milan, S. E.; Lester, M.

    2013-12-01

    We present a long term study, from January 1996 - August 2012, of the latitude of the Heppner-Maynard Boundary (HMB) measured at midnight using the northern hemisphere SuperDARN radars. The HMB represents the equatorward extent of ionospheric convection, and is used in this study as a measure of the global magnetospheric dynamics and activity. We find that the yearly distribution of HMB latitudes is single-peaked at 64° magnetic latitude for the majority of the 17-year interval. During 2003 the envelope of the distribution shifts to lower latitudes and a second peak in the distribution is observed at 61°. The solar wind-magnetosphere coupling function derived by Milan et al. (2012) suggests that the solar wind driving during this year was significantly higher than during the rest of the 17-year interval. In contrast, during the period 2008-2011 HMB distribution shifts to higher latitudes, and a second peak in the distribution is again observed, this time at 68° magnetic latitude. This time interval corresponds to a period of extremely low solar wind driving during the recent extreme solar minimum. This is the first statistical study of the polar cap area over an entire solar cycle, and the results demonstrate that there is a close relationship between the phase of the solar cycle and the area of the polar cap on a large scale statistical basis.

  1. Solar cycle dependence of substorm occurrence and duration: Implications for onset

    NASA Astrophysics Data System (ADS)

    Chu, Xiangning; McPherron, Robert L.; Hsu, Tung-Shin; Angelopoulos, Vassilis

    2015-04-01

    Magnetospheric substorms represent a major energy release process in Earth's magnetosphere. Their duration and intensity are coupled to solar wind input, but the precise way the solar wind energy is stored and then released is a matter of considerable debate. Part of the observational difficulty has been the gaps in the auroral electrojet index traditionally used to study substorm properties. In this study, we created a midlatitude positive bay (MPB) index to measure the strength of the substorm current wedge. Because this index is based on midlatitude magnetometer data that are available continuously over several decades, we can assemble a database of substorm onsets lasting 31 years (1982-2012). We confirmed that the MPB onsets have a good agreement (±2 min) with auroral onsets as determined by optical means on board the IMAGE mission and that the MPB signature of substorms is robust and independent of the stations' position relative to ionospheric currents. Using the MPB onset, expansion, and recovery as a proxy of the respective substorm quantities, we found that the solar cycle variation of substorm occurrence depends on solar wind conditions and has a most probable value of 80 min. In contrast, the durations of substorm expansion and recovery phases do not change with the solar cycle. This suggests that the frequency of energy unloading in the magnetosphere is controlled by solar wind conditions through dayside reconnection, but the unloading process related to flux pileup in the near-Earth region is controlled by the magnetosphere and independent of external driving.

  2. STATISTICAL STUDY OF STRONG AND EXTREME GEOMAGNETIC DISTURBANCES AND SOLAR CYCLE CHARACTERISTICS

    SciTech Connect

    Kilpua, E. K. J.; Olspert, N.; Grigorievskiy, A.; Käpylä, M. J.; Tanskanen, E. I.; Pelt, J.; Miyahara, H.; Kataoka, R.; Liu, Y. D.

    2015-06-20

    We study the relation between strong and extreme geomagnetic storms and solar cycle characteristics. The analysis uses an extensive geomagnetic index AA data set spanning over 150 yr complemented by the Kakioka magnetometer recordings. We apply Pearson correlation statistics and estimate the significance of the correlation with a bootstrapping technique. We show that the correlation between the storm occurrence and the strength of the solar cycle decreases from a clear positive correlation with increasing storm magnitude toward a negligible relationship. Hence, the quieter Sun can also launch superstorms that may lead to significant societal and economic impact. Our results show that while weaker storms occur most frequently in the declining phase, the stronger storms have the tendency to occur near solar maximum. Our analysis suggests that the most extreme solar eruptions do not have a direct connection between the solar large-scale dynamo-generated magnetic field, but are rather associated with smaller-scale dynamo and resulting turbulent magnetic fields. The phase distributions of sunspots and storms becoming increasingly in phase with increasing storm strength, on the other hand, may indicate that the extreme storms are related to the toroidal component of the solar large-scale field.

  3. F region plasma drifts over Arecibo - Solar cycle, seasonal, and magnetic activity effects

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.

    1993-01-01

    Characteristics of low-latitude F region plasma drifts are determined on the basis of Arecibo incoherent scatter measurements from 1981 to 1990. The measurements show large day-to-day variability even during magnetically quiet periods. The average poleward/perpendicular plasma drifts do not change significantly with season and solar cycle except in the midnight-morning sector. The zonal drifts show clear solar cycle and seasonal effects. The plasma drifts along the magnetic field lines exhibit large altitudinal and seasonal variations, particularly near solar minimum, and are generally anticorrelated with the perpendicular/north drifts. The drift patterns observed by the Arecibo and the middle and upper atmosphere radars have significantly different seasonal dependences. This is explained by electrodynamic effects in the corresponding local and conjugate ionospheres.

  4. Modulation Cycles of GCR Diurnal Anisotropy Variation

    NASA Astrophysics Data System (ADS)

    Yi, Y.; Oh, S. Y.

    The diurnal variations of GCR intensity observed by the ground NM stations represent the anisotropic GCR flow at 1 AU. It is generally believed that the variation of the local time of the GCR maximum intensity (phase) has 22-year period of two sunspot cycles. However, there even exists doubt on such anisotropy variation cycle. Those different interpretations come from the lack of enough data since determining the cycle of variation in precision requires data archived over long time of at least two cycles. In order to determine the cycle of GCR anisotropy variation, we carried out the statistical study on the diurnal variation of phase. We examined the 52 years data of Huancayo (Haleakala), 38-year data from Rome, 42-year data from Oulu NM stations. We used new method in determining the yearly mean phase. We applied the F-test to determine the statistically meaningful period of anisotropy phase variation. We found that the coupling coefficients indicating the differences in phase between the NM stations are not constant but dependent on the solar cycle. The phase variation has two components of 22-year and 11-year cycles. The NM station in the high latitude (low cut-off rigidity) shows mainly the 22-year cycle in phase controlled by the diffusion effect with the solar polar magnetic field reversal. However, the lower the latitude of NM station is, the higher contribution from 11-year cycle associated with the solar sunspot cycle. This additional phase variation might be regulated by the drift effect.

  5. The Fraction of Interplanetary Coronal Mass Ejections That Are Magnetic Clouds: Evidence for a Solar Cycle Variation

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    2004-01-01

    "Magnetic clouds" (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized by enhanced magnetic fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the solar wind. A comprehensive survey of ICMEs in the near- Earth solar wind during the ascending, maximum and early declining phases of solar cycle 23 in 1996 - 2003 shows that the MC fraction varies with the phase of the solar cycle, from approximately 100% (though with low statistics) at solar minimum to approximately 15% at solar maximum. A similar trend is evident in near-Earth observations during solar cycles 20 - 21, while Helios 1/2 spacecraft observations at 0.3 - 1.0 AU show a weaker trend and larger MC fraction.

  6. A new solar activity parameter and the strength of 5-cycle periodicity

    NASA Astrophysics Data System (ADS)

    Du, Z. L.

    2006-10-01

    A weak 5-cycle periodicity ( r = -0.64) is found in the maximum amplitudes of the modern era sunspot cycles (11-23), slightly stronger than the 8-cycle (Gleissberg) periodicity ( r = 0.60). We propose a new parameter called 'effective duration', defined as the total sunspot numbers in a cycle divided by the maximum amplitude. This parameter has two advantages: one is that it is almost independent of the exact definition of minimum timing; another is that the maximum amplitude is found to be highly correlated ( r = 0.86) with this parameter five cycles before, when applied to the smoothed monthly mean sunspot numbers in modern era. Implied is that this parameter carries some information of the amplitude five cycles later, and may become one of the parameters to study solar activity and the theory of solar dynamo. With the relationship above, the amplitude of cycle 24 is estimated to be 115.7 ± 19.7, where the error is the standard error.

  7. Chemistry climate model simulations of the effect of the 27 day solar rotational cycle on ozone

    NASA Astrophysics Data System (ADS)

    Kubin, A.; Langematz, U.; Brühl, C.

    2011-08-01

    The results from two simulations with the coupled chemistry climate model (CCM) ECHAM5/MESSy (EMAC-FUB) are analyzed for the effect of solar variability at the 27 day rotational time scale on ozone. One simulation is forced with constant spectral irradiances at the top of the atmosphere and the other one with daily varying irradiances using data of 1 year for solar maximum conditions. Consistent changes are applied to the photolysis scheme of the model. The model results show the main features of observed correlations between ozone and solar irradiance variability with a maximum positive correlation in the upper stratosphere and an anticorrelation in the mesosphere. The relative sensitivity of upper stratospheric ozone to changes in the solar ultraviolet flux is estimated to be 0.3 to 0.4% per 1% change in 205 nm flux. During periods of strong 27 day variability, a similar upper stratospheric ozone sensitivity is derived. However, when the daily solar irradiance variability is weak and dominated by the 13.5 day period, the ozone sensitivity is reduced in the subtropics. The modeled temperature response is consistent with the ozone signal. When averaged over one rotational cycle, the ozone and temperature response to a neglect of the 27 day cycle is weak and statistically insignificant in the stratosphere but of nonnegligible magnitude and statistically significant in the equatorial mesosphere. Our results suggest that ignoring daily solar flux variations on the 27 day time scale in transient CCM simulations does not lead to a significant degradation of the time mean ozone response in the stratosphere, while in the tropical mesosphere, significant errors of up to 3% may occur. This result does not exclude potential additional effects of 27 day solar cycle variability on stratospheric dynamics in winter which were, however, not the subject of this study.

  8. ON THE CONSTANCY OF THE ELECTRON TEMPERATURE IN THE EXPANDING CORONA THROUGHOUT SOLAR CYCLE 23

    SciTech Connect

    Habbal, Shadia Rifai; Morgan, Huw; Druckmueller, Miloslav; Ding, Adalbert

    2010-03-10

    A recent analysis of Fe emission lines observed during the total solar eclipses of 2006 March 29 and 2008 August 1 established the first empirical link between the electron temperature in the expanding corona and Fe charge states measured in interplanetary space. In this Letter, we use this link to infer this temperature throughout solar cycle 23 from in situ charge state measurements from the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) and on Ulysses. The distribution of the SWICS/ACE Fe charge states, which span cycle 23 from 1998 to 2009, is skewed with a peak centered on Fe{sup 8+}, Fe{sup 9+}, and Fe{sup 10+} and a tail spanning Fe{sup 12+} to Fe{sup 20+}. An iterative process based on this distribution and on the Fe ion fraction as a function of electron temperature yields a narrow peak at 1.1 x 10{sup 6} K. The tail in the measured charge state distribution is attributed to the sporadic release of material hotter than 2 x 10{sup 6} K from closed magnetic structures within the bulges of streamers. The Fe Ulysses charge state measurements between 1992 and 1997 from cycle 22 peaked at Fe{sup 11+}, indicative of a slightly higher temperature of 1.5 x 10{sup 6} K. The relative constancy of the electron temperature in the expanding corona throughout solar cycle 23 points to the presence of an unknown mechanism regulating the energy input to electrons in the acceleration region of the solar wind at all latitudes during this cycle.

  9. The solar cycle variation of the rates of CMEs and related activity

    NASA Technical Reports Server (NTRS)

    Webb, David F.

    1991-01-01

    Coronal mass ejections (CMEs) are an important aspect of the physics of the corona and heliosphere. This paper presents results of a study of occurrence frequencies of CMEs and related activity tracers over more than a complete solar activity cycle. To properly estimate occurrence rates, observed CME rates must be corrected for instrument duty cycles, detection efficiencies away from the skyplane, mass detection thresholds, and geometrical considerations. These corrections are evaluated using CME data from 1976-1989 obtained with the Skylab, SMM and SOLWIND coronagraphs and the Helios-2 photometers. The major results are: (1) the occurrence rate of CMEs tends to track the activity cycle in both amplitude and phase; (2) the corrected rates from different instruments are reasonably consistent; and (3) over the long term, no one class of solar activity tracer is better correlated with CME rate than any other (with the possible exception of type II bursts).

  10. Comparative Solar Wind Properties at 9AU between the maximum and late declining phases of the Solar Cycle and possible implications for the magnetospheric dynamics of Saturn

    NASA Astrophysics Data System (ADS)

    Went, D. R.; Jackman, C. M.; Forsyth, R. J.; Dougherty, M. K.; Crary, F. J.

    2009-04-01

    We compare and contrast the general plasma and magnetic field properties of the solar wind upstream of Saturn (8.5-9.5 AU) at solar maximum (Pioneer-11 encounter) and the late-declining (Cassini approach) phase of the solar cycle. In both cases we find a highly structured solar wind dominated by co-rotating interaction regions (CIRs), merged interaction regions (MIRs) and Interplanetary Coronal Mass Ejections (ICMEs) that temporarily disrupt an otherwise clear two sector interplanetary magnetic field structure. Solar rotations generally contain two CIR compressions with embedded crossings of the heliospheric current sheet. There is no conclusive evidence for (persistent) departures from the Parker Spiral IMF model in this region of the heliosphere at either phase of the solar cycle, consistent with previous analyses (Thomas and Smith 1980, Jackman et al. 2008). However it is clear that average plasma properties vary significantly between the maximum and late declining phases of the cycle and there are a number of small but notable deviations. In particular, the average dynamic pressure of the solar wind varies by a factor of roughly two between solar maximum and solar minimum with potentially important consequences for the dynamics of Saturn's magnetosphere. These consequences should become apparent as Cassini enters its extended Equinox Mission which should encompass the rising phase and eventually maximum of Solar Cycle 24. They will be discussed and predictions will be made for future Cassini observations.

  11. Predicting the Sunspot Cycle

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    2009-01-01

    The 11-year sunspot cycle was discovered by an amateur astronomer in 1844. Visual and photographic observations of sunspots have been made by both amateurs and professionals over the last 400 years. These observations provide key statistical information about the sunspot cycle that do allow for predictions of future activity. However, sunspots and the sunspot cycle are magnetic in nature. For the last 100 years these magnetic measurements have been acquired and used exclusively by professional astronomers to gain new information about the nature of the solar activity cycle. Recently, magnetic dynamo models have evolved to the stage where they can assimilate past data and provide predictions. With the advent of the Internet and open data policies, amateurs now have equal access to the same data used by professionals and equal opportunities to contribute (but, alas, without pay). This talk will describe some of the more useful prediction techniques and reveal what they say about the intensity of the upcoming sunspot cycle.

  12. Flow downstream of the heliospheric terminal shock: Magnetic field line topology and solar cycle imprint

    NASA Technical Reports Server (NTRS)

    Nerney, Steven; Suess, S. T.; Schmahl, E. J.

    1995-01-01

    The topology of the magnetic field in the heliosheath is illustrated using plots of the field lines. It is shown that the Archimedean spiral inside the terminal shock is rotated back in the heliosheath into nested spirals that are advected in the direction of the interstellar wind. The 22-year solar magnetic cycle is imprinted onto these field lines in the form of unipolar magnetic envelopes surrounded by volumes of strongly mixed polarity. Each envelope is defined by the changing tilt of the heliospheric current sheet, which is in turn defined by the boundary of unipolar high-latitude regions on the Sun that shrink to the pole at solar maximum and expand to the equator at solar minimum. The detailed shape of the envelopes is regulated by the solar wind velocity structure in the heliosheath.

  13. Energetic analysis of the white light emission associated to seismically active flares in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Buitrago-Casas, Juan Camilo; Martinez Oliveros, Juan Carlos; Glesener, Lindsay; Krucker, Sam

    2014-06-01

    Solar flares are explosive phenomena, thought to be driven by magnetic free energy accumulated in the solar corona. Some flares release seismic transients, "sunquakes", into the Sun's interior. Different mechanisms are being considered to explain how sunquakes are generated. We are conducting an analysis of white-light emission associated with those seismically active solar flares that have been reported by different authors within the current solar cycle. Seismic diagnostics are based upon standard time-distance techniques, including seismic holography, applied to Dopplergrams obtained by SDO/HMI and GONG. The relation between white-light emissions and seismic activity may provide important information on impulsive chromospheric heating during flares, a prospective contributor to seismic transient emission, at least in some instances. We develop a method to get an estimation of Energy associated whit white-light emission and compare those results whit values of energy needed to generate a sunquake according with holographic helioseismology techniques.

  14. Properties of Supergranulation During the Solar Minima of Cycles 22/23 and 23/24

    NASA Technical Reports Server (NTRS)

    Williams, Peter E.; Pesnell, W. Dean

    2011-01-01

    The solar minimum at the transition from cycle 23 to 24 was notable for its low level of activity and its extended duration. Among the various fields of study, the evolution of the solar convection zone may provide insight into the causes and consequences of this recent minimum. This study continues previous investigations of the characteristics of solar supergranulation, a convection component strongly linked to the structure of the magnetic field, namely the time-evolution of the global mean of supergranule cell size, determined from spectral analysis of MDI Dopplergrams from the two previous solar minima. Analyses of the global mean of supergranule sizes show a quasi-oscillatory nature to the evolution of this particular supergranule characteristic. Performing similar analyses on realistic, synthetic Doppler images show similar time-dependent characteristics. We conclude that the observed fluctuations are not observational artifacts, and that an underlying trend exists within the evolution of the supergranulation network.

  15. Traveling ionospheric disturbances (TIDs) at mid-latitudes - solar cycle phase dependence

    SciTech Connect

    Soicher, H.

    1988-06-01

    Faraday observations of total electron content (TEC) at Haifa, Israel (32.87 deg N, 35.09 deg E), during periods near the maximum (1980) and minimum (1984) phases of the current solar cycle have yielded information about the structure and variability of the ionosphere during both epochs in general, and about traveling ionospheric disturbances (TIDs) in particular. The TEC is characterized by the large differences in the seasonally dependent absolute values, by the generally occurring spatially confined postsunset secondary maxima during solar maximum which are absent during solar minimum, and by the regularly appearing modulations of the structure due to TIDs. There is a definite seasonal and solar phase dependence in the characteristics of the TIDs. This is expressed in terms of their frequency of occurrence, likely phase of the diurnal variation during which the occurrences take place, their absolute magnitudes, and the time rate of change of these magnitudes. 9 references.

  16. HIGH-LATITUDE SOLAR TORSIONAL OSCILLATIONS DURING PHASES OF CHANGING MAGNETIC CYCLE AMPLITUDE

    SciTech Connect

    Rempel, M.

    2012-05-01

    Torsional oscillations are variations of the solar differential rotation that are strongly linked to the magnetic cycle of the Sun. Helioseismic inversions have revealed significant differences in the high-latitude branch of torsional oscillations between cycle 23 and cycle 24. Here we employ a non-kinematic flux-transport dynamo model that has been used previously to study torsional oscillations and simulate the response of the high-latitude branch to a change in the amplitude of the magnetic cycle. It is found that a reduction of the cycle amplitude leads to an increase in the amplitude of differential rotation that is mostly visible as a drop in the high-latitude rotation rate. Depending on the amplitude of this adjustment the high-latitude torsional oscillation signal can become temporarily hidden due to the unknown changing mean rotation rate that is required to properly define the torsional oscillation signal.

  17. Climatology of low latitude ionosphere under effect of varying solar flux during solar cycle 23 and 24

    NASA Astrophysics Data System (ADS)

    Dashora, Nirvikar; Suresh, Sunanda

    2016-07-01

    The characteristics of quiet time equatorial and low latitude total electron content (TEC) over the Indian sector using GIM data (1998-2014) is obtained. For the first time the analysis is carried filtering out the solar flare and storm effects and time series of quiet time VTEC data from three locations namely dip equator and two low latitude conjugate locations in Indian sector are obtained. It is well known that a complex interplay among drivers of equatorial electrodynamics like Solar flux, dynamo electric field and meridional winds determine the daytime ionization and distribution in equatorial ionization anomaly zone. In this study, we have critically examined the role of varying solar flux and response of low latitude ionosphere with new and standardized definitions. The results are examined and interpreted in the context of large number of previous studies. The newly found features from this study are as follows. Marked difference in nature of equinoctial asymmetry is noted between solar cycle 23 and 24. Long absence of winter anomaly both during low and high solar activity (HSA) in LL (low latitude) regions is found. Climatology of the diurnal cycle is provided in four categories using new criteria for demarcation of solar activity levels. Highest correlation (~77%) between GIM ionospheric electron content (IEC) and PI (solar EUV proxy index) is noted over equator in contrast to previous studies. The minimum positive contribution of PI in variation of IEC requires minimum of 2 years of data and if more than 7-8 years of data is used, it saturates. RMS (root mean square) width of PI can be used to define the HSA. Strong QBO (quasi biennial oscillations) in IEC is noted in tune with the one in PI over both the LL location but QBO remains surprisingly subdued over equator. The semi-annual oscillations in GIM-IEC are found to be stronger at all locations during high solar activity and weaker between 2005 and 2011, whereas, the annual oscillations are found to

  18. Earth Radiation Budget Satellite extraterrestrial solar constant measurements - 1986-1987 increasing trend

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Barkstrom, Bruce R.; Harrison, Edwin F.; Gibson, Michael A.; Natarajan, Sudha M.; Edmonds, William L.; Mecherikunnel, Ann T.; Kyle, H. Lee

    1988-01-01

    From June 1986 through Nov 1987, the Earth Radiation Budget Satellite (ERBS) pyrheliometric measurements indicated that the solar constant was increasing approximately +0.02 percent per year. Earlier ERBS measurements indicated that the solar constant was declining approximately -0.03 percent per year during the 1984 through mid-1986 period. Since mid-1986 represents the beginning of solar cycle 22, it is believed that the reversal in the long-term solar constant trend may be linked to increased solar activity associated with the beginning of the 11-year sunspot cycle. The typical value of the solar constant was found to be 1365 Wm-2.

  19. Validation of solar-cycle changes in low-degree helioseismic parameters from the Birmingham Solar-Oscillations Network

    NASA Astrophysics Data System (ADS)

    Howe, R.; Davies, G. R.; Chaplin, W. J.; Elsworth, Y. P.; Hale, S. J.

    2015-12-01

    We present a new and up-to-date analysis of the solar low-degree p-mode parameter shifts from the Birmingham Solar-Oscillations Network over the past 22 years, up to the end of 2014. We aim to demonstrate that they are not dominated by changes in the asymmetry of the resonant peak profiles of the modes and that the previously published results on the solar-cycle variations of mode parameters are reliable. We compare the results obtained using a conventional maximum-likelihood estimation algorithm and a new one based on the Markov Chain Monte Carlo (MCMC) technique, both taking into account mode asymmetry. We assess the reliability of the solar-cycle trends seen in the data by applying the same analysis to artificially generated spectra. We find that the two methods are in good agreement. Both methods accurately reproduce the input frequency shifts in the artificial data and underestimate the amplitude and width changes by a small amount, around 10 per cent. We confirm earlier findings that the frequency and line width are positively correlated, and the mode amplitude anticorrelated, with the level of solar activity, with the energy supplied to the modes remaining essentially unchanged. For the mode asymmetry the correlation with activity is marginal, but the MCMC algorithm gives more robust results than the MLE (Maximum-Likelihood Estimate). The magnitude of the parameter shifts is consistent with earlier work. There is no evidence that the frequency changes we see arise from changes in the asymmetry, which would need to be much larger than those observed in order to give the observed frequency shift.

  20. Mars plasma system response to ICME transients at different phases of the solar cycle

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Hall, Benjamin E. S.; Witasse, Olivier; Mays, M. Leila; Blelly, Pierre-Louis; Andrews, David G.; Cartacci, Marco; Opgenoorth, Hermann; Milan, Stephen E.; Ambrosi, Richard M.; Odstrcil, Dusan; Plaut, Jeffrey J.; Imber, Suzanne

    2016-10-01

    We assess the reaction of the full Martian plasma system after the impact of different Interplanetary Coronal Mass Ejections (ICME) at Mars at different levels of solar activity and phases of the solar cycle 23/24. The Mars' plasma system behaviour is characterised from the surface of the planet to the bow shock position, which is the most external boundary where the solar wind directly interacts with the Martian system. Events at the extreme phases of the solar cycle will be given special attention, i.e. low and high solar activity periods, since variations in the maximum of the thermal pressure of the ionosphere are a key factor in order to create a significant/weak plasma obstacle to compete with the solar wind. The strength of this obstacle is ultimately controlled by the long-term EUV flux modulations. Likewise, the effect of such ICMEs on the plasma boundaries and induced magnetic fields within the ionosphere will be analysed in detail. The study uses data from TIMED, GOES and STEREOs observatories at 1 AU to monitor the solar irradiance and the propagation of such space weather transits. At Mars, long-term data come from Mars Express and Mars Odyssey missions since both spacecraft have been working from more than 12 years. The MAVEN and MSL missions provide supplementary data. Solar wind propagation modelling is used through the WSA-ENLIL+Cone model, as well as several numerical simulations of the ionosphere of Mars for such scenarios are made through the numerical/fluid TRANSMARS model.

  1. Variation of the Mn I 539.4 nm line with the solar cycle

    NASA Astrophysics Data System (ADS)

    Danilovic, S.; Solanki, S. K.; Livingston, W.; Krivova, N.; Vince, I.

    2016-03-01

    Context. As a part of the long-term program at Kitt Peak National Observatory (KPNO), the Mn i 539.4 nm line has been observed for nearly three solar cycles using the McMath telescope and the 13.5 m spectrograph in double-pass mode. These full-disk spectrophotometric observations revealed an unusually strong change of this line's parameters over the solar cycle. Aims: Optical pumping by the Mg II k line was originally proposed to explain these variations. More recent studies have proposed that this is not required and that the magnetic variability (i.e., the changes in solar atmospheric structure due to faculae) might explain these changes. Magnetic variability is also the mechanism that drives the changes in total solar irradiance variations (TSI). With this work we investigate this proposition quantitatively by using the same model that was earlier successfully employed to reconstruct the irradiance. Methods: We reconstructed the changes in the line parameters using the model SATIRE-S, which takes only variations of the daily surface distribution of the magnetic field into account. We applied exactly the same model atmospheres and value of the free parameter as were used in previous solar irradiance reconstructions to now model the variation in the Mn i 539.4 nm line profile and in neighboring Fe i lines. We compared the results of the theoretical model with KPNO observations. Results: The changes in the Mn i 539.4 nm line and a neighbouring Fe i 539.52 nm line over approximately three solar cycles are reproduced well by the model without additionally tweaking the model parameters, if changes made to the instrument setup are taken into account. The model slightly overestimates the change for the strong Fe i 539.32 nm line. Conclusions: Our result confirms that optical pumping of the Mn ii 539.4 nm line by Mg II k is not the main cause of its solar cycle change. It also provides independent confirmation of solar irradiance models which are based on the assumption

  2. Hot carbon corona in Mars' upper thermosphere and exosphere: 2. Solar cycle and seasonal variability

    NASA Astrophysics Data System (ADS)

    Lee, Yuni; Combi, Michael R.; Tenishev, Valeriy; Bougher, Stephen W.

    2014-12-01

    This work presents the variability over seasons (i.e., orbital position) and solar cycle of the Martian upper atmosphere and hot carbon corona. We investigate the production and distribution of energetic carbon atoms and the impacts on the total global hot carbon loss from dominant photochemical processes at five different cases: AL (aphelion and low solar activity), EL (equinox and low solar activity), EH (equinox and high solar activity), PL (perihelion and low solar activity), and PH (perihelion and high solar activity). We compare our results with previously published results but only on the limited cases due to the dearth of studies on solar EUV flux and seasonal variabilities. Photodissociation of CO and dissociative recombination of CO+ are generally regarded as the two most important source reactions for the production of hot atomic carbon. Of these two, photodissociation of CO is found to be the dominant source in all cases considered. To describe self-consistently the exosphere and the upper thermosphere, a 3-D kinetic particle simulator, the Adaptive Mesh Particle Simulator, and the 3-D Mars Thermosphere General Circulation Model are one-way coupled. The basic description of this hot carbon calculation can be found in the companion paper to this one. The spatial distributions and profiles of density and temperature and atmospheric loss rates are discussed for the cases considered. Finally, our computed global escape rate of hot carbon ranges from 5.28 × 1023 s-1 (AL) to 55.1 × 1023 s-1 (PL).

  3. Simulated kinetic effects of the corona and solar cycle on high altitude ion transport at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S. M.; Liemohn, M.; Fang, X.; Brain, D.; Ma, Y.

    2013-06-01

    We present results from the Mars Test Particle (MTP) simulation as part of a community‒wide model comparison in order to quantify the role of different neutral atmospheric conditions in planetary ion transport and escape. This study examines the effects of individual ion motion by simulating particle trajectories for three cases: solar minimum without the neutral corona, solar minimum with the inclusion of the neutral corona, and solar maximum with the inclusion of the neutral corona. The MTP simulates 1.5 billion test particles through background electric and magnetic fields computed by a global magnetohydrodynamic model. By implementing virtual detectors in the simulation, the MTP has generated velocity space distributions of pickup ions and quantifies the ion acceleration at different spatial locations. The study found that the inclusion of a hot neutral corona greatly