WorldWideScience

Sample records for current solar cycle

  1. Modeling the heliospheric current sheet: Solar cycle variations

    Science.gov (United States)

    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 (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.

  2. Proton activity of the Sun in current solar cycle 24

    CERN Document Server

    Li, Chuan; Fang, Cheng

    2014-01-01

    We present a study of 7 large solar proton events (SPEs) of current solar cycle 24 (from 2009 January up to date). They were recorded by GOES spacecraft with highest proton fluxes over 200 pfu for energies $>$10 MeV. In situ particle measurements show that: (1) The profiles of the proton fluxes are highly dependent of the locations of their solar sources, namely flares or coronal mass ejections (CMEs); (2) The solar particle release (SPR) times fall in the decay phase of the flare emission, and are in accordance with the times when the CMEs travel to an average height of 7.9 solar radii; (3) The time differences between the SPR and the flare peak are also dependent of the locations of the solar active regions (ARs). The results tend to support the concept of proton acceleration by the CME-driven shock, even though there exists a possibility of particle acceleration at flare site with subsequent perpendicular diffusion of accelerated particles in the interplanetary magnetic field (IMF). We derive the integral ...

  3. Solar cycle in current reanalyses: (nonlinear attribution study

    Directory of Open Access Journals (Sweden)

    A. Kuchar

    2014-12-01

    Full Text Available This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11 year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (Support Vector Regression, Neural Networks besides the traditional linear approach. The analysis was applied to several current reanalysis datasets for the 1979–2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how this type of data resolves especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the lower and upper stratosphere were found to be sufficiently robust and in qualitative agreement with previous observational studies. The analysis also pointed to the solar signal in the ozone datasets (i.e. MERRA and ERA-Interim not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. Consequently the results obtained by linear regression were confirmed by the nonlinear approach through all datasets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. Furthermore, the seasonal dependence of the solar response was also discussed, mainly as a source of dynamical causalities in the wave propagation characteristics in the zonal wind and the induced meridional circulation in the winter hemispheres. The hypothetical mechanism of a weaker Brewer Dobson circulation was reviewed together with discussion of polar vortex stability.

  4. Solar cycle in current reanalyses: (non)linear attribution study

    Science.gov (United States)

    Kuchar, A.; Sacha, P.; Miksovsky, J.; Pisoft, P.

    2014-12-01

    This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11 year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (Support Vector Regression, Neural Networks) besides the traditional linear approach. The analysis was applied to several current reanalysis datasets for the 1979-2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how this type of data resolves especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the lower and upper stratosphere were found to be sufficiently robust and in qualitative agreement with previous observational studies. The analysis also pointed to the solar signal in the ozone datasets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. Consequently the results obtained by linear regression were confirmed by the nonlinear approach through all datasets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. Furthermore, the seasonal dependence of the solar response was also discussed, mainly as a source of dynamical causalities in the wave propagation characteristics in the zonal wind and the induced meridional circulation in the winter hemispheres. The hypothetical mechanism of a weaker Brewer Dobson circulation was reviewed together with discussion of polar vortex stability.

  5. Dynamo Models of the Solar Cycle: Current Trends and Future Prospects

    CERN Document Server

    Nandy, Dibyendu

    2011-01-01

    The magnetic cycle of the Sun, as manifested in the cyclic appearance of sunspots, significantly influences our space environment and space-based technologies by generating what is now termed as space weather. Long-term variation in the Sun's magnetic output also influences planetary atmospheres and climate through modulation of solar irradiance. Here, I summarize the current state of understanding of this magnetic cycle, highlighting important observational constraints, detailing the kinematic dynamo modeling approach and commenting on future prospects.

  6. Solar Cycle Predictions

    Science.gov (United States)

    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.

  7. Re-visit of ionosphere storm morphology with TEC data in the current solar cycle

    Science.gov (United States)

    Cander, Ljiljana R.

    2016-02-01

    This paper addresses the magnetosphere-ionosphere-thermosphere (M-I-T) storm effects, with emphasis on 15 major geomagnetic storms in the current solar cycle as far as May 2015. It is an ionosphere storm response-case analysis based on the vertical total electron content (VTEC) observations at mid-latitude Global Positioning System (GPS) ground-based station HERS (0.33°E, 50.86°N). The time dependent features of ionospheric storms are examined with ∆VTEC defined as the percent change of VTEC during storm time relative to quiet time represented by its monthly median value at the same UT. During a specific event of April 2010 storm, the F2 layer peak electron density (NmF2) data at collocated Chilton (358.67°E, 51.70°N) ionosonde station are used for comparison. The seasonal dependence of the storms is identified and the strength of both positive and negative storms phases is correlated with the intensity of the geomagnetic storms. The focus is on localized characteristics of these solar-terrestrial disturbances and the relative roles of inherent physical and chemical processes that appear to be so changeable from one event to the other generating significant variability in ionospheric responses. The implications of these results for the persistence, certainty and consequently predictability of ionosphric storms are discussed and conclusions drown.

  8. The Solar Cycle

    CERN Document Server

    Hathaway, David H

    2015-01-01

    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 10.7cm 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.

  9. The Solar Cycle.

    Science.gov (United States)

    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.

  10. Solar Cycle Predictions (Invited Review)

    Science.gov (United States)

    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.

  11. The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

    Science.gov (United States)

    Kuchar, A.; Sacha, P.; Miksovsky, J.; Pisoft, P.

    2015-06-01

    This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11-year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (support vector regression, neural networks) besides the multiple linear regression approach. The analysis was applied to several current reanalysis data sets for the 1979-2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how these types of data resolve especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the tropical stratosphere were found to be in qualitative agreement with previous attribution studies, although the agreement with observational results was incomplete, especially for JRA-55. The analysis also pointed to the solar signal in the ozone data sets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. The results obtained by linear regression were confirmed by the nonlinear approach through all data sets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. The seasonal evolution of the solar response was also discussed in terms of dynamical causalities in the winter hemispheres. The hypothetical mechanism of a weaker Brewer-Dobson circulation at solar maxima was reviewed together with a discussion of polar vortex behaviour.

  12. Solar Cycle 24 and the Solar Dynamo

    Science.gov (United States)

    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.

  13. Solar Cycle #24 and the Solar Dynamo

    Science.gov (United States)

    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

  14. Solar cycle 25: another moderate cycle?

    CERN Document Server

    Cameron, Robert H; Schuessler, Manfred

    2016-01-01

    Surface flux transport simulations for the descending phase of cycle 24 using random sources (emerging bipolar magnetic regions) with empirically determined scatter of their properties provide a prediction of the axial dipole moment during the upcoming activity minimum together with a realistic uncertainty range. The expectation value for the dipole moment around 2020 $(2.5\\pm1.1\\,$G) is comparable to that observed at the end of cycle 23 (about $2\\,$G). The empirical correlation between the dipole moment during solar minimum and the strength of the subsequent cycle thus suggests that cycle 25 will be of moderate amplitude, not much higher than that of the current cycle. However, the intrinsic uncertainty of such predictions resulting from the random scatter of the source properties is considerable and fundamentally limits the reliability with which such predictions can be made before activity minimum is reached.

  15. Solar cycle variations in the solar wind

    Science.gov (United States)

    Freeman, John W.; Lopez, Ramon E.

    1986-01-01

    The solar cycle variations of various solar wind parameters are reviewed. It is shown that there is a gradual decrease in the duration of high-speed streams from the declining phase of solar cycle 20 through the ascending phase of cycle 21 and a corresponding decrease in the annual average of the proton speed toward solar maximum. Beta, the ratio of the proton thermal pressure to magnetic pressure, undergoes a significant solar cycle variation, as expected from the variation in the IMF. Individual hourly averages of beta often exceed unity with 20 cases exceeding 10 and one case as high as 25. The Alfven Mach number shows a solar cycle variation similar to beta, lower aboard solar maximum. High-speed streams can be seen clearly in epsilon and the y component of the interplanetary magnetic field.

  16. Solar Cycle 24: is the peak coming?

    CERN Document Server

    Sello, Stefano

    2012-01-01

    Solar cycle activity forecasting, mainly its magnitude and timing, is an essential issue for numerous scientific and technological applications: in fact, during an active solar period, many strong eruptions occur on the Sun with increasing frequency, such as flares, coronal mass ejections, high velocity solar wind photons and particles, which can severely affect the Earth's ionosphere and the geomagnetic field, with impacts on the low atmosphere. Thus it is very important to develop reliable solar cycle prediction methods for the incoming solar activity. The current solar cycle 24 appeared unusual from many points of view: an unusually extended minimum period, and a global low activity compared to those of the previous three or four cycles. Currently, there are many different evidences that the peak in the northern hemisphere already occurred at 2011.6 but not yet in the southern hemisphere. In this brief note we update the peak prediction and its timing, based on the most recent observations.

  17. The asymmetry of the heliospheric current sheet during solar cycle 23: The last dance of the bashful ballerina?

    Science.gov (United States)

    Mursula, K.; Virtanen, I. I.

    2010-05-01

    The heliospheric magnetic field has long been hemispherically asymmetric so that the field in the northern hemisphere is weaker and the area larger than in the south. This asymmetry, also called the bashful ballerina, has existed during three-year intervals in the late declining to minimum phase of solar cycles 16-22. We study here the HMF and its hemispheric asymmetry during solar cycle 23. We find that the latitudinal ordering of HMF sectors at low latitudes is exceptional in SC 23: the normal latitudinal variation was not established in the south by Spring 2009, implying that the Rosenberg-Coleman rule is abnormally delayed or broken during this cycle. Comparing the radial field at 1AU and at the coronal source surface footpoint, we show that the HCS was southward shifted even in SC 23 but the shift is considerably smaller than in earlier cycles. We also study the HMF observations during the third perihelion pass of the Ulysses probe in 2007, and find that the northern field was some 0.2 nT stronger than the southern field and that the whole HCS region was clearly shifted southward by about 2°-5°. Accordingly, the north-south asymmetry existed even in SC 23 but was largely masked out in ecliptic observations due to the exceptionally weak polar fields, leading to an abnormally large HCS tilt angle and a wide equatorial belt region. We also note that historical evidence at the ecliptic suggests a connection between solar dipole strength and the size of north-south asymmetry observed there. Based on this, one can predict that, after the present period of weak solar activity started in SC 23, the hemispheric asymmetry will grow again with increasing activity, but the orientation of the asymmetry will be opposite. Thus, after SC 23, the solar ballerina will not be bashful for some 100-150 years.

  18. Dynamo Models of the Solar Cycle

    Directory of Open Access Journals (Sweden)

    Charbonneau Paul

    2005-06-01

    Full Text Available This paper reviews recent advances and current debates in modeling the solar cycle as a hydromagnetic dynamo process. Emphasis is placed on (relatively simple dynamo models that are nonetheless detailed enough to be comparable to solar cycle observations. After a brief overview of the dynamo problem and of key observational constraints, we begin by reviewing the various magnetic field regeneration mechanisms that have been proposed in the solar context. We move on to a presentation and critical discussion of extant solar cycle models based on these mechanisms. We then turn to the origin of fluctuations in these models, including amplitude and parity modulation, chaotic behavior, and intermittency. The paper concludes with a discussion of our current state of ignorance regarding various key questions, the most pressing perhaps being the identification of the physical mechanism(s responsible for the generation of the Sun's poloidal magnetic field component.

  19. Activity Cycle of Solar Filaments

    Indian Academy of Sciences (India)

    K. J. Li; Q. X. Li; P. X. Gao; J. Mu; H. D. Chen; T. W. Su

    2007-06-01

    Long-term variation in the distribution of the solar filaments observed at the Observatorie de Paris, Section de Meudon from March 1919 to December 1989 is presented to compare with sunspot cycle and to study the periodicity in the filament activity, namely the periods of the coronal activity with the Morlet wavelet used. It is inferred that the activity cycle of solar filaments should have the same cycle length as sunspot cycle, but the cycle behavior of solar filaments is globally similar in profile with, but different in detail from, that of sunspot cycles. The amplitude of solar magnetic activity should not keep in phase with the complexity of solar magnetic activity. The possible periods in the filament activity are about 10.44 and 19.20 years. The wavelet local power spectrum of the period 10.44 years is statistically significant during the whole consideration time. The wavelet local power spectrum of the period 19.20 years is under the 95% confidence spectrum during the whole consideration time, but over the mean red-noise spectrum of = 0.72 before approximate Carrington rotation number 1500, and after that the filament activity does not statistically show the period. Wavelet reconstruction indicates that the early data of the filament archive (in and before cycle 16) are more noiseful than the later (in and after cycle 17).

  20. Analysis of geomagnetically induced currents at a low-latitude region over the solar cycles 23 and 24: comparison between measurements and calculations

    Directory of Open Access Journals (Sweden)

    Barbosa Cleiton

    2015-01-01

    Full Text Available Geomagnetically Induced Currents (GIC are a space weather effect, which affects ground-based technological structures at all latitudes on the Earth’s surface. GIC occurrence and amplitudes have been monitored in power grids located at high and middle latitudes since 1970s and 1980s, respectively. This monitoring provides information about the GIC intensity and the frequency of occurrence during geomagnetic storms. In this paper, we investigate GIC occurrence in a power network at low latitudes (in the central Brazilian region during the solar cycles 23 and 24. Calculated and measured GIC data are compared for the most intense geomagnetic storms (i.e. −50 < Dst < −50 nT of the solar cycle 24. The results obtained from this comparison show a good agreement. The success of the model employed for the calculation of GIC leads to the possibility of determining GIC for events during the solar cycle 23 as well. Calculated GIC in one transformer reached ca. 30 A during the “Halloween storm” in 2003 whilst most frequent intensities lie below 10 A. The normalized inverse cumulative frequency for GIC data was calculated for the solar cycle 23 in order to perform a statistical analysis. It was found that a q-exponential Tsallis distribution fits the calculated GIC frequency distribution for more than 99% of the data. This analysis provides an overview of the long-term GIC monitoring at low latitudes and suggests new insight into critical phenomena involved in the GIC generation.

  1. Ground level observations of relativistic solar particles on Oct 29th, 2015: Is it a new GLE on the current solar cycle?

    CERN Document Server

    Augusto, C R A; de Oliveira, M N; Nepomuceno, A A; Fauth, A C

    2016-01-01

    On Oct. 29th, 2015, the Earth crossed through a fold in the heliospheric current sheet. This is called a "solar sector boundary crossing". Under this circumstances, a large coronal mass ejection (CME) occurred at 2:24 UT, behind the west limb on the sun. Therefore, the boundary crossing occurred when in the blast's nearby environment was filled with energetic particles accelerated by the CME shock waves, spacecraft measurements (ACE and GOES) have shown that in such a case, protons with energies at least up to 30 MeV were stored within the range of the sector boundary. Thus, a fraction of the solar energetic particles (SEP) from CME, reached Earth around 03:00 UT in the aftermath of the solar blast, reaching the condition of an S1 (minor) radiation storm level. The effect at ground level was a small increase in the counting rate in some ground based detectors, such as the South Pole Neutron Monitor (NM) and a sharp peak observed in the counting rate in the New-Tupi detector in Rio de Janeiro, Brazil and Thule...

  2. THE BIMODAL STRUCTURE OF THE SOLAR CYCLE

    Energy Technology Data Exchange (ETDEWEB)

    Du, Z. L., E-mail: zldu@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    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.

  3. Solar spectral irradiance changes during cycle 24

    Energy Technology Data Exchange (ETDEWEB)

    Marchenko, S. V.; DeLand, M. T. [Also at NASA/Goddard Space Flight Center, Greenbelt, MD, USA. (United States)

    2014-07-10

    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 ∼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 λ ≳ 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.

  4. Properties and Surprises of Solar Activity XXIII Cycle

    Science.gov (United States)

    Ishkov, V. N.

    2010-12-01

    The main properties of the 23rd cycle match almost completely those of average-magnitude solar cycles, and some of the features of the cycle may indicate a change in the generation mode of magnetic fields in the solar convection zone. If this is the case, the Sun enters a period of intermediate and weak cycles of solar activity (SA) in terms of the Wolf number, which may last for 3 to 6 solar cycles. The main development stages of solar cycle 23 are the following: minimum of solar cycle 22: April 1996 (W* = 8.0); maximum of the smoothed relative sunspot number: April 2000; global polarity reversal of the general solar magnetic field: July to December 2000; secondary maximum of the relative sunspot number: November 2001; maximum of the 10.7-cm radio flux: February 2002; phase of the cycle maximum: October 1999 to June 2002; beginning of the decrease phase: July 2002; the point of minimum of the current SA cycle: December 2008. Solar cycle 23 has presented two powerful flare-active sunspot groups, in September 2005 and December 2006 (+5.5 and +6.6 years from the maximum) which by flare potential occupy 4th and 20th place among the most flare-active regions for the last four solar cycles. The unprecedented duration of the relative sunspot numbers fall that has led to already record duration of the last solar cycle among authentic cycles (since 1849) became the next surprise of development of solar activity during the last cycle. The phase of the minimum began in May 2005 and lasted for 4.5 years. Thus, the new solar cycle 24 has begun in January 2009.

  5. Solar storms, cycles and topology

    Directory of Open Access Journals (Sweden)

    Lundstedt H.

    2010-12-01

    Full Text Available Solar storms are produced due to plasma processes inside and between coronal loops. These loops are topologically examined using knot and braid theory. Solar cycles are topologically explored with a complex generalization of the three ordinary differential equations studied by Lorenz. By studying the Poincaré map we give numerical evidence that the flow has an attractor with fractal structure. The period is defined as the time needed for a point on a hyperplane to return to the hyperplane again. The periods are distributed in an interval. For large values of the Dynamo number there is a long tail toward long periods and other interesting comet-like features. We also found a relationship between the intensity of a cycle and the length for the previous cycle. Maunder like minima are also appearing. These general relations found for periods can further be physically interpreted with improved helioseismic estimates of the parameters used by the dynamical systems. Solar Dynamic Observatory is expected to offer such improved measurements.

  6. Helioseismic Solar Cycle Changes and Splitting Coefficients

    Indian Academy of Sciences (India)

    S. C. Tripathy; Kiran Jain; A. Bhatnagar

    2000-09-01

    Using the GONG data for a period over four years, we have studied the variation of frequencies and splitting coefficients with solar cycle. Frequencies and even-order coefficients are found to change significantly with rising phase of the solar cycle. We also find temporal variations in the rotation rate near the solar surface.

  7. Predicting Solar Cycle 25 using Surface Flux Transport Model

    Science.gov (United States)

    Imada, Shinsuke; Iijima, Haruhisa; Hotta, Hideyuki; Shiota, Daiko; Kusano, Kanya

    2017-08-01

    It is thought that the longer-term variations of the solar activity may affect the Earth’s climate. Therefore, predicting the next solar cycle is crucial for the forecast of the “solar-terrestrial environment”. To build prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar activity is intensively discussed. Because we can determine the polar magnetic field at the solar minimum roughly 3 years before the next solar maximum, we may discuss the next solar cycle 3years before. Further, the longer term (~5 years) prediction might be achieved by estimating the polar magnetic field with the Surface Flux Transport (SFT) model. Now, we are developing a prediction scheme by SFT model as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction) and adapting to the Cycle 25 prediction. The predicted polar field strength of Cycle 24/25 minimum is several tens of percent smaller than Cycle 23/24 minimum. The result suggests that the amplitude of Cycle 25 is weaker than the current cycle. We also try to obtain the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters will be used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle and discuss the initial results for Cycle 25 prediction.

  8. A thermodynamic cycle for the solar cell

    Science.gov (United States)

    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.

  9. Solar Wind Variation with the Cycle

    Indian Academy of Sciences (India)

    I. S. Veselovsky; A. V. Dmitriev; A. V. Suvorova; M. V. Tarsina

    2000-09-01

    The cyclic evolution of the heliospheric plasma parameters is related to the time-dependent boundary conditions in the solar corona. "Minimal" coronal configurations correspond to the regular appearance of the tenuous, but hot and fast plasma streams from the large polar coronal holes. The denser, but cooler and slower solar wind is adjacent to coronal streamers. Irregular dynamic manifestations are present in the corona and the solar wind everywhere and always. They follow the solar activity cycle rather well. Because of this, the direct and indirect solar wind measurements demonstrate clear variations in space and time according to the minimal, intermediate and maximal conditions of the cycles. The average solar wind density, velocity and temperature measured at the Earth's orbit show specific decadal variations and trends, which are of the order of the first tens per cent during the last three solar cycles. Statistical, spectral and correlation characteristics of the solar wind are reviewed with the emphasis on the cycles.

  10. Forecasting the solar activity cycle: new insights

    CERN Document Server

    Nandy, Dibyendu

    2013-01-01

    Having advanced knowledge of solar activity is important because the Sun's magnetic output governs space weather and impacts technologies reliant on space. However, the irregular nature of the solar cycle makes solar activity predictions a challenging task. This is best achieved through appropriately constrained solar dynamo simulations and as such the first step towards predictions is to understand the underlying physics of the solar dynamo mechanism. In Babcock-Leighton type dynamo models, the poloidal field is generated near the solar surface whereas the toroidal field is generated in the solar interior. Therefore a finite time is necessary for the coupling of the spatially segregated source layers of the dynamo. This time delay introduces a memory in the dynamo mechanism which allows forecasting of future solar activity. Here we discuss how this forecasting ability of the solar cycle is affected by downward turbulent pumping of magnetic flux. With significant turbulent pumping the memory of the dynamo is ...

  11. 25 MeV Solar Proton Events in Cycle 24 and Previous Cycles

    Science.gov (United States)

    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.

  12. Evolution of the solar radius during the solar cycle 24 rise time

    Science.gov (United States)

    Meftah, Mustapha

    2015-08-01

    One of the real motivations to observe the solar radius is the suspicion that it might be variable. Possible temporal variations of the solar radius are important as an indicator of internal energy storage and as a mechanism for changes in the total solar irradiance. Measurements of the solar radius are of great interest within the scope of the debate on the role of the Sun in climate change. Solar energy input dominates the surface processes (climate, ocean circulation, wind, etc.) of the Earth. Thus, it appears important to know on what time scales the solar radius and other fundamental solar parameters, like the total solar irradiance, vary in order to better understand and assess the origin and mechanisms of the terrestrial climate changes. The current solar cycle is probably going to be the weakest in 100 years, which is an unprecedented opportunity for studying the variability of the solar radius during this period. This paper presents more than four years of solar radius measurements obtained with a satellite and a ground-based observatory during the solar cycle 24 rise time. Our measurements show the benefit of simultaneous measurements obtained from ground and space observatories. Space observations are a priori most favourable, however, space entails also technical challenges, a harsh environment, and a finite mission lifetime. The evolution of the solar radius during the rising phase of the solar cycle 24 show small variations that are out of phase with solar activity.

  13. Cycle 23 Variation in Solar Flare Productivity

    CERN Document Server

    Hudson, Hugh; McTiernan, Jim

    2014-01-01

    The NOAA listings of solar flares in cycles 21-24, including the GOES soft X-ray magnitudes, enable a simple determination of the number of flares each flaring active region produces over its lifetime. We have studied this measure of flare productivity over the interval 1975-2012. The annual averages of flare productivity remained approximately constant during cycles 21 and 22, at about two reported M or X flares per region, but then increased significantly in the declining phase of cycle 23 (the years 2004-2005). We have confirmed this by using the independent RHESSI flare catalog to check the NOAA events listings where possible. We note that this measure of solar activity does not correlate with the solar cycle. The anomalous peak in flare productivity immediately preceded the long solar minimum between cycles 23 and 24.

  14. Solar cycle full-shape predictions: a global error evaluation for cycle 24

    CERN Document Server

    Sello, Stefano

    2016-01-01

    There are many proposed prediction methods for solar cycles behavior. In a previous paper we updated the full-shape curve prediction of the current solar cycle 24 using a non-linear dynamics method and we compared the results with the predictions collected by the NOAA/SEC prediction panel, using observed data up to October 2010. The aim of the present paper is to give a quantitative evaluation, a posteriori, of the performances of these prediction methods using a specific global error, updated on a monthly basis, which is a measure of the global performance on the predicted shape (both amplitude and phase) of the solar cycle. We suggest also the use of a percent cycle similarity degree, to better evaluate the predicted shape of the solar cycle curve.

  15. Open cycle cooling systems using solar energy

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.; Sovrano, M.

    Open cycle cooling systems are particularly suitable for utilizing solar energy. In all these systems the adsorption and absorption phenomena are very important, hence they are described separately. The cycles used are essentially two: the Baum-Kakabaev cycle using liquid absorbers and the dehumidification/humidification cycle where also adsorbent substances can be utilized. Solar energy is used in the regeneration process of dehumidifying substances. Reactivation modes can be various: suitability of one mode or the other can depend on the climate of the site where the system is installed.

  16. The origin of the solar magnetic cycle

    Indian Academy of Sciences (India)

    Arnab Rai Choudhuri

    2011-07-01

    After summarizing the relevant observational data, we discuss how a study of flux tube dynamics in the solar convection zone helps us to understand the formation of sunspots. Then we introduce the flux transport dynamo model and assess its success in modelling both the solar cycle and its departures from strictly periodic behaviour.

  17. Phase lags of solar hemispheric cycles

    CERN Document Server

    Muraközy, J

    2013-01-01

    The North-South asymmetry of solar activity is variable in time and strength. We analyse the long-term variation of the phase lags of hemispheric cycles and check a conjectured relationship between these phase lags and the hemispheric cycle strengths. Sunspot data are used from cycles 12-23 in which the separation of northern and southern hemispheres is possible. The centers of mass of the hemispheric cycle profiles were used to study the phase relations and relative strengths of the hemispheric cycles. This approach considers a cycle as a whole and disregards the short-term fluctuations of the cycle time profile. The phase of the hemispheric cycles shows an alternating variation: the northern cycle leads in 4 cycles and follows in 4 cycles. No significant relationship is found between the phase and strength differences of the hemispheric cycles. The period of 4+4 cycles appears to be close to the Gleissberg cycle and may provide a key to its physical background. It may raise a new aspect in the solar dynamo ...

  18. Nonlinear solar cycle forecasting: theory and perspectives

    Directory of Open Access Journals (Sweden)

    A. L. Baranovski

    2008-02-01

    Full Text Available In this paper we develop a modern approach to solar cycle forecasting, based on the mathematical theory of nonlinear dynamics. We start from the design of a static curve fitting model for the experimental yearly sunspot number series, over a time scale of 306 years, starting from year 1700 and we establish a least-squares optimal pulse shape of a solar cycle. The cycle-to-cycle evolution of the parameters of the cycle shape displays different patterns, such as a Gleissberg cycle and a strong anomaly in the cycle evolution during the Dalton minimum. In a second step, we extract a chaotic mapping for the successive values of one of the key model parameters – the rate of the exponential growth-decrease of the solar activity during the n-th cycle. We examine piece-wise linear techniques for the approximation of the derived mapping and we provide its probabilistic analysis: calculation of the invariant distribution and autocorrelation function. We find analytical relationships for the sunspot maxima and minima, as well as their occurrence times, as functions of chaotic values of the above parameter. Based on a Lyapunov spectrum analysis of the embedded mapping, we finally establish a horizon of predictability for the method, which allows us to give the most probable forecasting of the upcoming solar cycle 24, with an expected peak height of 93±21 occurring in 2011/2012.

  19. Encore of the Bashful ballerina in solar cycle 23

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Global water cycle and solar activity variations

    Science.gov (United States)

    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.

  2. LIFE CYCLE COST ANALYSIS OF SOLAR PONDS

    Directory of Open Access Journals (Sweden)

    Murat ÖZTÜRK

    2008-03-01

    Full Text Available Solar ponds are the systems which collect solar energy and store it for long periods of time. For effective and efficient use of these systems in the country, concepts relating economy of solar ponds which generated hot water from the sun must be known besides their physical properties. Life cycle cost analysis is a systematic analytical method that helps identify and evaluate the environmental impacts of a specific process or competing processes. In order to quantify the costs, resource consumption, and energy use, material and energy balances are performed in a cradle-to-grave manner on the operations required to transform raw materials into useful products. In this study; life cycle cost analysis of reflecting covered and non covered solar ponds are calculated for a volume of 3.5x3.5x2 cubic meters and presented. Also the energies extractable for these solar ponds in Goller Region climatic conditions are given.

  3. Solar cycle modulation of Southern Annular Mode

    Science.gov (United States)

    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.

  4. Coronal Mass Ejections of Solar Cycle 23

    Indian Academy of Sciences (India)

    Nat Gopalswamy

    2006-06-01

    I summarize the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by far the most extensive data, which made it possible to fully establish the properties of CMEs as a phenomenon of utmost importance to Sun–Earth connection as well as to the heliosphere. I also discuss various subsets of CMEs that are of primary importance for their impact on Earth.

  5. Helioseismology and the Solar Cycle: Past, Present and Future

    Indian Academy of Sciences (India)

    Frank Hill

    2008-03-01

    A major goal of helioseismology is to understand the mechanism of the solar cycle. In this paper, some results of helioseismic observations relevant to the cycle are briefly reviewed, the current state-of-the-art is discussed, and near-term future directions are sketched out. Topics covered include the internal rotation rate; activity-related parameter variations; the tachocline; far-side imaging; the torsional oscillation; and meridional flows.

  6. Hubble Space Telescope solar cell module thermal cycle test

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. The Prediction of Maximum Amplitudes of Solar Cycles and the Maximum Amplitude of Solar Cycle 24

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We present a brief review of predictions of solar cycle maximum ampli-tude with a lead time of 2 years or more. It is pointed out that a precise predictionof the maximum amplitude with such a lead-time is still an open question despiteprogress made since the 1960s. A method of prediction using statistical character-istics of solar cycles is developed: the solar cycles are divided into two groups, ahigh rising velocity (HRV) group and a low rising velocity (LRV) group, dependingon the rising velocity in the ascending phase for a given duration of the ascendingphase. The amplitude of Solar Cycle 24 can be predicted after the start of thecycle using the formula derived in this paper. Now, about 5 years before the startof the cycle, we can make a preliminary prediction of 83.2-119.4 for its maximumamplitude.

  9. A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jay R; Wing, Simon

    2005-03-08

    The nonlinear dependencies inherent to the historical K(sub)p data stream (1932-2003) are examined using mutual information and cumulant based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original K(sub)p data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maximum. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solar minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to one week. Because the solar wind driver variables, VB(sub)s and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.

  10. Current-Enhanced Quantum Well Solar Cells

    Institute of Scientific and Technical Information of China (English)

    LOU Chao-Gang; SUN Qiang; XU Jun; ZHANG Xiao-Bing; LEI Wei; WANG Bao-Ping; CHEN Wen-Jun; QIAO Zai-Xiang

    2006-01-01

    We present the experimental results that demonstrate the enhancement of the short-circuit current of quantum well solar cells. The spectral response shows that the introduction of quantum wells extends the absorption spectrum of solar cells. The current densities under different truncated spectrums significantly increase, showing that quantum well solar cells are suitable to be the middle cells of GaInP/GaAs/Ge triple-junction solar cells to increase their overall conversion efficiency.

  11. Geomagnetism during solar cycle 23: Characteristics

    Directory of Open Access Journals (Sweden)

    Jean-Louis Zerbo

    2013-05-01

    Full Text Available 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.

  12. Geomagnetism during solar cycle 23: Characteristics.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  14. Solar cycle distribution of major geomagnetic storms

    Institute of Scientific and Technical Information of China (English)

    Gui-Ming Le; Zi-Yu Cai; Hua-Ning Wang; Zhi-Qiang Yin; Peng Li

    2013-01-01

    We examine the solar cycle distribution of major geomagnetic storms (Dst ≤-100 nT),including intense storms at the level of-200 nT< Dst ≤-100 nT,great storms at-300 nT< Dst ≤-200 nT,and super storms at Dst ≤-300 nT,which occurred during the period of 1957-2006,based on Dst indices and smoothed monthly sunspot numbers.Statistics show that the majority (82%) of the geomagnetic storms at the level of Dst ≤-100 nT that occurred in the study period were intense geomagnetic storms,with 12.4% ranked as great storms and 5.6% as super storms.It is interesting to note that about 27% of the geomagnetic storms that occurred at all three intensity levels appeared in the ascending phase of a solar cycle,and about 73% in the descending one.Statistics also show that 76.9% of the intense storms,79.6% of the great storms and 90.9% of the super storms occurred during the two years before a solar cycle reached its peak,or in the three years after it.The correlation between the size of a solar cycle and the percentage of major storms that occurred,during the period from two years prior to maximum to three years after it,is investigated.Finally,the properties of the multi-peak distribution for major geomagnetic storms in each solar cycle is investigated.

  15. Ozone depletion during solar proton events in solar cycle 21

    Science.gov (United States)

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

    1985-01-01

    Ozone profile data from the Solar Backscattered Ultraviolet Instrument on Nimbus 7 from 1979 to the present and clear cases of ozone destruction associated with five sudden proton events (SPEs) on June 7, 1979, August 21, 1979, October 13-14, 1981, July 13, 1982, and December 8, 1982 are found. During the SPE on July 13, 1982, the largest of this solar cycle, no depletion at all at 45 km is observed, but there is a 15 percent ozone depletion at 50 km increasing to 27 percent at 55 km, all at a solar zenith angle of 85 deg. A strong variation of the observed depletion with solar zenith angle is found, with maximum depletion occurring at the largest zenith angles (near 85 deg) decreasing to near zero for angles below about 70 deg. The observed depletion is short lived, disappearing within hours of the end of the SPE.

  16. The Heliosphere through the Solar Activity Cycle

    CERN Document Server

    Balogh, André; Suess, Steven T

    2008-01-01

    Understanding how the Sun changes though its 11-year sunspot cycle and how these changes affect the vast space around the Sun – the heliosphere – has been one of the principal objectives of space research since the advent of the space age. This book presents the evolution of the heliosphere through an entire solar activity cycle. The last solar cycle (cycle 23) has been the best observed from both the Earth and from a fleet of spacecraft. Of these, the joint ESA-NASA Ulysses probe has provided continuous observations of the state of the heliosphere since 1990 from a unique vantage point, that of a nearly polar orbit around the Sun. Ulysses’ results affect our understanding of the heliosphere from the interior of the Sun to the interstellar medium - beyond the outer boundary of the heliosphere. Written by scientists closely associated with the Ulysses mission, the book describes and explains the many different aspects of changes in the heliosphere in response to solar activity. In particular, the authors...

  17. Solar cycle variations of magnetopause locations

    Science.gov (United States)

    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.

  18. Can Asymmetry of Solar Activity be Extended into Extended Cycle?

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With the use of the Royal Greenwich Observatory data set of sunspot groups, an attempt is made to examine the north-south asymmetry of solar activity in the "extended" solar cycles. It is inferred that the asymmetry established for individual solar cycles does not extend to the "extended" cycles.

  19. Numerical evaluation of the Kalina cycle for concentrating solar power plants

    DEFF Research Database (Denmark)

    Modi, Anish

    of using a Kalina cycle is evaluated with a thermoeconomic optimization with a turbine inlet temperature of 500 C for a central receiver solar power plant with direct vapour generation, and 370 C for a parabolic trough solar power plant with Therminol VP-1 as the solar field heat transfer fluid. No thermal......Concentrating solar power plants use a number of reflecting mirrors to focus and convert the incident solar energy to heat, and a power cycle to convert this heat into electricity. One of the key challenges currently faced by the solar industry is the high cost of electricity production....... These costs may be driven down by developing more cost-effective plant components and improving the system designs. This thesis focuses on the power cycle aspect of the concentrating solar power plants by studying the use a Kalina cycle with ammonia-water mixtures as the cycle working fluid. The potential...

  20. Space weather Preparing for the Maximum of the Solar Cycle

    Science.gov (United States)

    Shaltout, Mosalam

    : Space Environments Group preparing for the maximum of the solar cycle 24 where the current plan envisage that the National second Earth Research satellite EgyptSat2 will be launched in 2012. For that, forecasting the solar activity at 2012 is very important. The plan depend on the long-term prediction by using 10.7cm of Ottawa data (1947-2008) and applying fast Fourier transform FFT on this time series. Also, Using the Artificial Intelligence to predict the maximum activity by Fuzzy modeling. Also, Short-term prediction for Coronal mass ejection CMEs by the artificial satellite STEREO observations, beside other satellites as SOHO, Hinde, SDO, Solar orbiter sentinels, Solar Probe in collaboration with Paris Observatory in Meudon, France.

  1. Solar total irradiance in cycle 23

    CERN Document Server

    Krivova, N A; Schmutz, W

    2011-01-01

    The apparently unusual behaviour of the TSI during the most recent minimum of solar activity has been interpreted as evidence against solar surface magnetism as the main driver of the secular change in the TSI. We test claims that the evolution of the solar surface magnetic field does not reproduce the observed TSI in cycle 23. We use sensitive, 60-minute averaged MDI magnetograms and quasi-simultaneous continuum images as an input to our SATIRE-S model and calculate the TSI variation over cycle 23, sampled roughly twice-monthly. The computed TSI is then compared to the PMOD composite of TSI measurements and to the data from two individual instruments, SORCE/TIM and UARS/ACRIM II, that monitored the TSI during the declining phase of cycle 23 and over the previous minimum in 1996, respectively. Excellent agreement is found between the trends shown by the model and almost all sets of measurements. The only exception is the early, i.e. 1996 to 1998, PMOD data. Whereas the agreement between the model and the PMOD...

  2. A solar cycle lengthwise series of solar diameter measurements

    Science.gov (United States)

    Penna, J. L.; Andrei, A. H.; Boscardin, S. C.; Neto, E. Reis; d'Ávila, V. A.

    2010-02-01

    The measurements of the solar photospheric diameter rank among the most difficult astronomic observations. Reasons for this are the fuzzy definition of the limb, the SNR excess, and the adverse daytime seeing condition. As a consequence there are very few lengthy and consistent time series of such measurements. Using modern techniques, just the series from the IAG/USP and from Calern/OCA span more than one solar cycle. The Rio de Janeiro Group observations started in 1997, and therefore in 2008 one complete solar cycle time span can be analyzed. The series shares common principles of observation and analysis with the ones afore mentioned, and it is complementary on time to them. The distinctive features are the larger number of individual points and the improved precision. The series contains about 25,000 single observations, evenly distributed on a day-by-day basis. The typical error of a single observation is half an arc-second, enabling us to investigate variations at the expected level of tens of arc-second on a weekly basis. These features prompted to develop a new methodology for the investigation of the heliophysical scenarios leading to the observed variations, both on time and on heliolatitude. The algorithms rely on running averages and time shifts to derive the correlation and statistical incertitude for the comparison of the long term and major episodes variations of the solar diameter against activity markers. The results bring support to the correlation between the diameter variation and the solar activity, but evidentiating two different regimens for the long term trend and the major solar events.

  3. Update on a Solar Magnetic Catalog Spanning Four Solar Cycles

    Science.gov (United States)

    Vargas-Acosta, Juan Pablo; Munoz-Jaramillo, Andres; Vargas Dominguez, Santiago; Werginz, Zachary; DeLuca, Michael D.; Longcope, Dana; Harvey, J. W.; Windmueller, John; Zhang, Jie; Martens, Petrus C.

    2017-08-01

    Bipolar magnetic regions (BMRs) are the cornerstone of solar cycle propagation, the building blocks that give structure to the solar atmosphere, and the origin of the majority of space weather events. However, in spite of their importance, there is no homogeneous BMR catalog spanning the era of systematic solar magnetic field measurements. Here we present the results of an ongoing project to address this deficiency applying the Bipolar Active Region Detection (BARD) code to magnetograms from the 512 Channel of the Kitt Peak Vaccum Telescope, SOHO/MDI, and SDO/HMI.The BARD code automatically identifies BMRs and tracks them as they are rotated by differential rotation. The output of the automatic detection is supervised by a human observer to correct possible mistakes made by the automatic algorithm (like incorrect pairings and tracking mislabels). Extra passes are made to integrate fragmented regions as well as to balance the flux between BMR polarities. At the moment, our BMR database includes nearly 10,000 unique objects (detected and tracked) belonging to four separate solar cycles (21-24).

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

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Robin [SAIC; Davenport, Roger [SAIC; Talbot, Jan [UCSD; Herz, Richard [UCSD; Genders, David [Electrosynthesis Co.; Symons, Peter [Electrosynthesis Co.; Brown, Lloyd [TChemE

    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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Janet G. Luhmann

    2013-05-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  8. Solar Sources of $^{3}$He-rich Solar Energetic Particle Events in Solar Cycle 24

    OpenAIRE

    Nitta, Nariaki V.; Mason, Glenn M.; Wang, Linghua; Cohen, Christina M. S.; Wiedenbeck, Mark E.

    2015-01-01

    Using high-cadence extreme-ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 $^{3}$He-rich solar energetic particle (SEP) events at $\\lesssim$1 MeV nucleon$^{-1}$ that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of $^{3}$He-rich events with type III radio bursts and electron events as observ...

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

    Science.gov (United States)

    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).

  10. Why is the Sun No Longer Accelerating Particles to High Energy in Solar Cycle 24?

    Science.gov (United States)

    Mewaldt, R. A.; Cohen, C. M.; Li, G.; Mason, G. M.; Smith, C. W.; von Rosenvinge, T. T.; Vourlidas, A.

    2015-12-01

    Why is the Sun No Longer Accelerating Particles to High Energy in Solar Cycle 24?Measurements by ACE, STEREO, and GOES show that the number of large Solar Energetic Particle (SEP) events in solar cycle 24 is reduced by a factor of ~2 compared to this point of solar cycle 23, while the fluences of >10 MeV/nuc ions from H to Fe are reduced by factors ranging from ~4 to ~10. Compared to solar Cycle 22 and 23, the fluence of >100 MeV protons is reduced by factors of ~7 to ~10 in the current cycle. A common element of these observations is that the observed Cycle-24 energy spectra have "breaks" that suddenly steepen 2 to 4 times lower in energy/nucleon than in Cycle 23. We investigate the origin of these cycle-to-cycle spectral differences by evaluating possible factors that control the maximum energy of CME-shock-accelerated particles in the two cycles, including seed-particle densities of suprathermal ions, the interplanetary magnetic field strength and turbulence level, and properties of the associated CMEs. The effect of these conditions will be evaluated in the context of existing SEP acceleration models by comparing SEP data with simulations and with analytic evaluations of the maximum kinetic energy to which CME shocks can accelerate solar energetic ions from H to Fe. Understanding the properties that control the maximum kinetic energy of CME-shock accelerated particles has important implications for predicting future solar activity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.-M.; Colaninno, R., E-mail: yi.wang@nrl.navy.mil, E-mail: robin.colaninno@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    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.

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

    Science.gov (United States)

    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.

  13. Solar cycle variations in the ionosphere of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Cano, B.; Lester, M.; Witasse, Ol; Blelly, P.L.; Cartacci, M.; Radicella, S.M.; Herraiz, M.

    2016-07-01

    Solar cycle variations in solar radiation create notable changes in the Martian ionosphere, which have been analysed with Mars Express plasma datasets in this paper. In general, lower densities and temperatures of the ionosphere are found during the low solar activity phase, while higher densities and temperatures are found during the high solar activity phase. In this paper, we assess the degree of influence of the long term solar flux variations in the ionosphere of Mars. (Author)

  14. SOLAR SOURCES OF {sup 3}He-RICH SOLAR ENERGETIC PARTICLE EVENTS IN SOLAR CYCLE 24

    Energy Technology Data Exchange (ETDEWEB)

    Nitta, Nariaki V. [Lockheed Martin Advanced Technology Center, Dept/A021S, B/252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Mason, Glenn M. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Wang, Linghua [Institute of Space Physics and Applied Technology, Peking University, Beijing 100871 (China); Cohen, Christina M. S. [California Institute of Technology, Pasadena, CA 91125 (United States); Wiedenbeck, Mark E., E-mail: nitta@lmsal.com, E-mail: glenn.mason@jhuapl.edu, E-mail: wanglhwang@gmail.com, E-mail: cohen@srl.caltech.edu, E-mail: mark.e.wiedenbeck@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2015-06-20

    Using high-cadence EUV images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 {sup 3}He-rich solar energetic particle events at ≲1 MeV nucleon{sup −1} that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of {sup 3}He-rich events with type III radio bursts and electron events as observed by Wind. The source locations are further verified in EUV images from the Solar and Terrestrial Relations Observatory, which provides information on solar activities in the regions not visible from the Earth. Based on AIA observations, {sup 3}He-rich events are not only associated with coronal jets as emphasized in solar cycle 23 studies, but also with more spatially extended eruptions. The properties of the {sup 3}He-rich events do not appear to be strongly correlated with those of the source regions. As in the previous studies, the magnetic connection between the source region and the observer is not always reproduced adequately by the simple potential field source surface model combined with the Parker spiral. Instead, we find a broad longitudinal distribution of the source regions extending well beyond the west limb, with the longitude deviating significantly from that expected from the observed solar wind speed.

  15. A New Challenge to Solar Dynamo Models from Helioseismic Observations: The Latitudinal Dependence of the Progression of the Solar Cycle

    Science.gov (United States)

    Simoniello, R.; Tripathy, S. C.; Jain, K.; Hill, F.

    2016-09-01

    The onset of the solar cycle at mid-latitudes, the slowdown in the drift of sunspots toward the equator, the tail-like attachment, and the overlap of successive cycles at the time of minimum activity are delicate issues in models of the αΩ dynamo wave and the flux transport dynamo. Very different parameter values produce similar results, making it difficult to understand the origin of the properties of these solar cycles. We use helioseismic data from the Global Oscillation Network Group to investigate the progression of the solar cycle as observed in intermediate-degree global p-mode frequency shifts at different latitudes and subsurface layers, from the beginning of solar cycle 23 up to the maximum of the current solar cycle. We also analyze those for high-degree modes in each hemisphere obtained through the ring-diagram technique of local helioseismology. The analysis highlights differences in the progression of the cycle below 15° compared to higher latitudes. While the cycle starts at mid-latitudes and then migrates equatorward/poleward, the sunspot eruptions of the old cycle are still ongoing below 15° latitude. This prolonged activity causes a delay in the onset of the cycle and an overlap of successive cycles, whose extent differs in the two hemispheres. Then the activity level rises faster, reaching a maximum characterized by a single-peak structure as opposed to the double peak at higher latitudes. Afterwards the descending phase shows up with a slower decay rate. The latitudinal properties of the progression of the solar cycle highlighted in this study provide useful constraints for discerning among the multitude of solar dynamo models.

  16. First Colombian Solar Radio Interferometer: current stage

    Science.gov (United States)

    Guevara Gómez, J. C.; Martínez Oliveros, J. C.; Calvo-Mozo, B.

    2017-10-01

    Solar radio astronomy is a fast developing research field in Colombia. Here, we present the scientific goals, specifications and current state of the First Colombian Solar Radio Interferometer consisting of two log-periodic antennas covering a frequency bandwidth op to 800 MHz. We describe the importance and benefits of its development to the radioastronomy in Latin America and its impact on the scientific community and general public.

  17. Solar Sources of $^{3}$He-rich Solar Energetic Particle Events in Solar Cycle 24

    CERN Document Server

    Nitta, Nariaki V; Wang, Linghua; Cohen, Christina M S; Wiedenbeck, Mark E

    2015-01-01

    Using high-cadence extreme-ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 $^{3}$He-rich solar energetic particle (SEP) events at $\\lesssim$1 MeV nucleon$^{-1}$ that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of $^{3}$He-rich events with type III radio bursts and electron events as observed by Wind. The source locations are further verified in EUV images from the Solar and Terrestrial Relations Observatory, which provides information on solar activities in the regions not visible from the Earth. Based on AIA observations, $^{3}$He-rich events are not only associated with coronal jets as emphasized in solar cycle 23 studies, but also with more spatially extended eruptions. The properties of the $^{3}$He-rich events do not appear to be strongly correlated with those of the source regions. As in the previous...

  18. Heliospheric Magnetic Fields, Energetic Particles, and the Solar Cycle

    Indian Academy of Sciences (India)

    Peter Kiraly

    2000-09-01

    The heliosphere is the region filled with magnetized plasma of mainly solar origin. It extends from the solar corona to well beyond the planets, and is separated from the interstellar medium by the heliopause. The latter is embedded in a complex and still unexplored boundary region. The characteristics of heliospheric plasma, fields, and energetic particles depend on highly variable internal boundary conditions, and also on quasi-stationary external ones. Both galactic cosmic rays and energetic particles of solar and heliospheric origin are subject to intensity variations over individual solar cycles and also from cycle to cycle. Particle propagation is controlled by spatially and temporally varying interplanetary magnetic fields, frozen into the solar wind. An overview is presented of the main heliospheric components and processes, and also of the relevant missions and data sets. Particular attention is given to flux variations over the last few solar cycles, and to extrapolated effects on the terrestrial environment.

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

    Directory of Open Access Journals (Sweden)

    Marchenko Sergey V.

    2016-01-01

    Full Text Available 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.

  20. Solar photovoltaics: current state and trends

    Science.gov (United States)

    Milichko, V. A.; Shalin, A. S.; Mukhin, I. S.; Kovrov, A. E.; Krasilin, A. A.; Vinogradov, A. V.; Belov, P. A.; Simovski, C. R.

    2016-08-01

    Basic aspects of current solar photovoltaics (PVs) are reviewed, starting from the recently developed already-on-the-market first-generation solar cells and ending with promising but not yet commercialized third-generation cells and materials possibly leading to new cell designs. The emphasis is on the physical principles of operation of various solar cells, which are divided into several groups according to our classification scheme. To make the picture complete, some technological and economic aspects of the field are discussed. A separate chapter considers antireflection coatings and light-trapping textures — structures which, while not having appeared yet in the PV review literature, are an integral part of the solar cells.

  1. Solar Spectral Irradiance Variability in Cycle 24: Observations and Models

    CERN Document Server

    Marchenko, S V; Lean, J L

    2016-01-01

    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 265-500 nm during the on-going Cycle 24. We supplement the OMI data with concurrent observations from the GOME-2 and SORCE instruments and find fair-to-excellent, depending on wavelength, agreement among the observations and predictions of the NRLSSI2 and SATIRE-S models.

  2. A New Challenge to Solar Dynamo Models from Helioseismic Observations: The Latitudinal Dependence of the Progression of the Solar Cycle

    CERN Document Server

    Simoniello, R; Jain, K; Hill, F

    2016-01-01

    The solar cycle onset at mid-latitudes, the slow down of the sunspot drift toward the equator, the tail-like attachment and the overlap of successive cycles at the time of activity minimum are delicate issues in $\\alpha\\Omega$ dynamo wave and flux transport dynamo models. Very different parameter values produce similar results, making it difficult to understand the origin of these solar cycle properties. We use GONG helioseismic data to investigate the progression of the solar cycle as observed in intermediate-degree global $p$-mode frequency shifts at different latitudes and subsurface layers, from the beginning of solar cycle 23 up to the maximum of the current solar cycle. We also analyze those for high-degree modes in each hemisphere obtained through the ring-diagram technique of local helioseismology. The analysis highlighted differences in the progression of the cycle below 15\\degr\\ compared to higher latitudes. While the cycle starts at mid-latitudes and then migrates equatorward/poleward, the sunspot ...

  3. Three Cycles of the Solar Toroidal Magnetic Field and This Peculiar Minimum

    CERN Document Server

    Lo, Leyan; Scherrer, Phil

    2010-01-01

    Thirty-four years of WSO (Wilcox Solar Observatory) and thirteen years of SOHO/MDI (Michelson Doppler Imager on the Solar and Heliospheric Observatory) magnetograms have been studied to measure the east-west inclination angle, indicating the toroidal component of the photospheric magnetic field. This analysis reveals that the large-scale toroidal component of the global magnetic field is antisymmetric around the equator and reverses direction in regions associated with flux from one solar cycle compared to the next. The toroidal field revealed the first early signs of cycle 24 at high latitudes, especially in the northern hemisphere, appearing as far back as 2003 in the WSO data and 2004 in MDI. As in previous cycles, the feature moves gradually equatorward. Cycles overlap and the pattern associated with each cycle lasts about 17 years. Even though the polar field at the current solar minimum is significantly lower than the three previous minima, the toroidal field pattern is similar.

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

    Science.gov (United States)

    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.

  5. The cause of the weak solar cycle 24

    CERN Document Server

    Jiang, Jie; Schuessler, Manfred

    2015-01-01

    The ongoing 11-year cycle of solar activity is considerably less vigorous than the three cycles before. It was preceded by a very deep activity minimum with a low polar magnetic flux, the source of the toroidal field responsible for solar magnetic activity in the subsequent cycle. Simulation of the evolution of the solar surface field shows that the weak polar fields and thus the weakness of the present cycle 24 are mainly caused by a number of bigger bipolar regions emerging at low latitudes with a `wrong' (i.e., opposite to the majority for this cycle) orientation of their magnetic polarities in the North-South direction, which impaired the growth of the polar field. These regions had a particularly strong effect since they emerged within $\\pm10^\\circ$ latitude from the solar equator.

  6. Polar Coronal Holes During Solar Cycles 22 and 23

    Institute of Scientific and Technical Information of China (English)

    Jun Zhang; J. Woch; S. Solanki

    2005-01-01

    Data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses and synoptic maps from Kitt Peak are used to analyze the polar coronal holes of solar activity cycles 22 and 23 (from 1990 to end of 2003). In the beginning of the declining phase of solar cycles 22 and 23, the north polar coronal holes (PCHs) appear about one year earlier than the ones in the south polar region.The solar wind velocity and the solar wind ionic charge composition exhibit a characteristic dependence on the solar wind source position within a PCH. From the center toward the boundary of a young PCH, the solar wind velocity decreases,coinciding with a shift of the ionic charge composition toward higher charge states.However, for an old PCH, the ionic charge composition does not show any obvious change, although the latitude evolution of the velocity is similar to that of a young PCH.

  7. Latitude of Ephemeral Regions as Indicator of Strength of Solar Cycles

    CERN Document Server

    Tlatov, Andrey G

    2010-01-01

    Digitized images of full disk CaK spectroheliograms from two solar observatories were used to study cycle variation of ephemeral regions (ERs) over ten solar cycles 14-23. We calculate monthly averaged unsigned latitude of ERs and compare it with annual sunspot number. We find that average latitude of ERs can be used as a predictor for strength of solar cycle. For a short-term prediction (dT about 1-2 years), maximum latitude of ephemeral regions (in current cycle) defines the amplitude of that cycle (higher is the latitude of ERs, larger are the amplitudes of sunspot cycle). For a long-term prediction (dT about 1.5 solar cycles), latitude of ERs at declining phase of n-th cycle determines the amplitude of (n+2)-th sunspot cycle (lower is the latitude of ERs, stronger is the cycle). Using this latter dependency, we forecast the amplitude of sunspot cycle 24 at W=92 +/- 13 (in units of annual sunspot number).

  8. Forecasting the Peak of the Present Solar Activity Cycle

    Science.gov (United States)

    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.

  9. Solar powered Stirling cycle electrical generator

    Science.gov (United States)

    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.

  10. Predicting Maximum Sunspot Number in Solar Cycle 24

    Indian Academy of Sciences (India)

    Nipa J Bhatt; Rajmal Jain; Malini Aggarwal

    2009-03-01

    A few prediction methods have been developed based on the precursor technique which is found to be successful for forecasting the solar activity. Considering the geomagnetic activity aa indices during the descending phase of the preceding solar cycle as the precursor, we predict the maximum amplitude of annual mean sunspot number in cycle 24 to be 111 ± 21. This suggests that the maximum amplitude of the upcoming cycle 24 will be less than cycles 21–22. Further, we have estimated the annual mean geomagnetic activity aa index for the solar maximum year in cycle 24 to be 20.6 ± 4.7 and the average of the annual mean sunspot number during the descending phase of cycle 24 is estimated to be 48 ± 16.8.

  11. Starspots, stellar cycles and stellar flares: Lessons from solar dynamo models

    Science.gov (United States)

    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.

  12. Multi-timescale Solar Cycles and the Possible Implications

    CERN Document Server

    Tan, Baolin

    2010-01-01

    Based on analysis of the annual averaged relative sunspot number (ASN) during 1700 -- 2009, 3 kinds of solar cycles are confirmed: the well-known 11-yr cycle (Schwabe cycle), 103-yr secular cycle (numbered as G1, G2, G3, and G4, respectively since 1700); and 51.5-yr Cycle. From similarities, an extrapolation of forthcoming solar cycles is made, and found that the solar cycle 24 will be a relative long and weak Schwabe cycle, which may reach to its apex around 2012-2014 in the vale between G3 and G4. Additionally, most Schwabe cycles are asymmetric with rapidly rising-phases and slowly decay-phases. The comparisons between ASN and the annual flare numbers with different GOES classes (C-class, M-class, X-class, and super-flare, here super-flare is defined as $\\geq$ X10.0) and the annal averaged radio flux at frequency of 2.84 GHz indicate that solar flares have a tendency: the more powerful of the flare, the later it takes place after the onset of the Schwabe cycle, and most powerful flares take place in the de...

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

    Science.gov (United States)

    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

  14. North–South Distribution of Solar Flares during Cycle 23

    Indian Academy of Sciences (India)

    Bhuwan Joshi; P. Pant; P. K. Manoharan

    2006-06-01

    In this paper, we investigate the spatial distribution of solar flares in the northern and southern hemispheres of the Sun that occurred during the period 1996 to 2003. This period of investigation includes the ascending phase, the maximum and part of the descending phase of solar cycle 23. It is revealed that the flare activity during this cycle is low compared to the previous solar cycle, indicating the violation of Gnevyshev–Ohl rule. The distribution of flares with respect to heliographic latitudes shows a significant asymmetry between northern and southern hemisphere which is maximum during the minimum phase of the solar cycle. The present study indicates that the activity dominates the northern hemisphere in general during the rising phase of the cycle (1997–2000). The dominance of northern hemisphere shifted towards the southern hemisphere after the solar maximum in 2000 and remained there in the successive years. Although the annual variations in the asymmetry time series during cycle 23 are quite different from cycle 22, they are comparable to cycle 21.

  15. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    Science.gov (United States)

    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.

  16. The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

    Indian Academy of Sciences (India)

    S. D. Bao; G. X. Ai; H. Q. Zhang

    2000-09-01

    We compute the signs of two different current helicity parameters (i.e., best and ) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative best and 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameter shows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

  17. Observation of Hysteresis between Solar Activity Indicators and -mode Frequency Shifts for Solar Cycle 22

    Indian Academy of Sciences (India)

    S. C. Tripathy; Brajesh Kumar; Kiran Jain; A. Bhatnagar

    2000-09-01

    Using intermediate degree p-mode frequency data sets for solar cycle 22, we find that the frequency shifts and magnetic activity indicators show a ``hysteresis" phenomenon. It is observed that the magnetic indices follow different paths for the ascending and descending phases of the solar cycle while for radiative indices, the separation between the paths are well within the error limits.

  18. Solar cycle lengths and climate: A reference revisited - Reply

    DEFF Research Database (Denmark)

    Lassen, K.; Friis-Christensen, Eigil

    2000-01-01

    In a critical assessment of the results regarding a possible association between solar activity variations and climate by Friis-Christensen and Lassen [1991] and Lassen and Friis-Christensen [1995], Laut and Gundermann [this issue] conclude that the correlation between the solar cycle length para...

  19. Role of the vapor compression cycle in solar energy utilization

    Energy Technology Data Exchange (ETDEWEB)

    Kush, Jr, E A

    1978-01-01

    The vapor compression cycle lends itself to solar energy utilization in two important ways. Its ability to utilize a relatively low temperature heat supply to produce space heating via heat pumps allows the use of solar input to the evaporator to provide potential Coefficients of Performance which are 2 to 3 times higher than present electric driven heat pumps, and the use of relatively inexpensive solar collectors is possible since the collection temperatures can be low grade. Secondly, the compression process of the vapor cycle can be powered by a solar-driven heat engine, typically using a Rankine cycle, for solar cooling purposes. Discriminating coupling of solar with vapor compression allows the well-developed technology and manufacturing capability of the vapor compression industry to be brought into play in the solar field, widening its base and promoting its diversification. The cycle thermodynamics, potential practical hardware, and R and D projects in both of these areas are reviewed. Particular attention is given to the Solar Assisted Heat Pump and its characteristics and the heat pump simulator activities at Brookhaven National Laboratory.

  20. Data Assimilation and Uncertainties in Early Solar Cycle Predictions

    Science.gov (United States)

    Kitiashvili, Irina

    2017-08-01

    Stochastic nature of solar activity variations together with our limited knowledge of the dynamo mechanism and subsurface dynamics causes uncertainty in predictions of the solar cycle. For improving the physics-based predictions we can take advantage of the mathematical data assimilation approach that allows us to take into account both, observational errors and model uncertainties, and provide estimates of the next solar cycle along with prediction uncertainties. In this study we use the Parker's migratory dynamo model together with the equation of magnetic helicity balance, which reproduces main properties of the sunspot cycles and allow us to minimize discrepancies between the observed global activity variations and the model solution. The test simulation runs show that a reliable prediction can be obtained for two phases of preceding solar cycle: 1) if the polar field reversals shortly after the solar maxima (strong toroidal field and weak poloidal field), and 2) during the solar minima (strongest poloidal and weak toroidal fields). The early estimate of Cycle 25 obtained by this method shows that this cycle will start in 2019 - 2020, reach the maximum in 2023 - 2024, and that the mean sunspot number at the maximum will be about 90 (for the v2.0 sunspot number series).

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

    Science.gov (United States)

    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.

  2. Can origin of the 2400-year cycle of solar activity be caused by solar inertial motion?

    Directory of Open Access Journals (Sweden)

    I. Charvátová

    Full Text Available A solar activity cycle of about 2400 years has until now been of uncertain origin. Recent results indicate it is caused by solar inertial motion. First we describe the 178.7-year basic cycle of solar motion. The longer cycle, over an 8000 year interval, is found to average 2402.2 years. This corresponds to the Jupiter/Heliocentre/Barycentre alignments (9.8855 × 243. Within each cycle an exceptional segment of 370 years has been found characterized by a looping pattern by a trefoil or quasitrefoil geometry. Solar activity, evidenced by 14C tree-ring proxies, shows the same pattern. Solar motion is computable in advance, so this provides a basis for future predictive assessments. The next 370-year segment will occur between AD 2240 and 2610.

    Key words: Solar physics (celestial mechanics

  3. ISCC Kuraymat Integrated Solar Combined Cycle Power Plant in Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Brakmann, G.

    2006-07-01

    The New and Renewable Energy Authority (NREA) of Egypt intends to implement an Integrated Solar Combined Cycle Power Plant, ISCC Kuraymat, to be located about 95 km south of Cairo, on the eastern side of the river Nile, at a northern latitude of 29{sup o} 16' and an eastern longitude of 31{sup o} 15'. The complete ISCC Project shall be implemented in three (3) contract lots: One (1) Contract Lot for Solar Island as EPC cum OandM contract for engineering, procurement, construction, testing, commissioning and five (5) years operation and maintenance; (Two contracts will be used for this Lot (Solar Island), one for EPC and one for the OandM part of the Lot.) The Solar Island shall consist of a parabolic trough solar field capable to generate about 110 MW (thermal) of solar heat at a temperature of 393{sup o}C, the related IandC and control room and the heat transfer fluid (HTF) system up to the HTF inlet and outlet flanges of the Solar Heat Exchanger(s). The Contractor for Solar Island shall guarantee the supply of solar heat to the Solar Heat Exchanger(s) as a function of normal direct solar irradiation (DNI) and of solar position. One (1) Contract for Combined Cycle Island as EPC contract for engineering, procurement, construction, testing and commissioning and extended two (2) year warranty period. The Combined Cycle Island shall consist of one (1) or two (2) gas turbine(s) with ISO rating of about 80 MWe (total), one (1) or two (2) heat recovery steam generator(s) (HRSG), one (1) steam turbine of about 70 MWe, solar heat exchanger(s) capable to absorb about 110 MW (thermal) of solar heat plus all associated balance of plant equipment. The Contractor(s) for Combined Cycle Island shall guarantee the supply of electricity and the heat rate as a function of ambient temperature and as a function of solar heat supply from the Solar Island. One (1) Contract for Combined Cycle Island as OandM contract for five (5) year operation and maintenance. (Author)

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

    Science.gov (United States)

    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 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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Chunlan; Wang, Jingxiu, E-mail: cljin@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    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.

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

    Science.gov (United States)

    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.

  8. Organic Rankine Cycle with Solar Heat Storage in Paraffin Way

    Directory of Open Access Journals (Sweden)

    Constantin LUCA

    2015-06-01

    Full Text Available The paper presents an electricity generation system based on an Organic Rankine Cycle and proposed storing the amount of the heat produced by the solar panels using large volume of paraffin wax. The proposed working fluid is R-134a refrigerant. The cycle operates at very low temperatures. A efficiency of 6,55% was obtained.

  9. Current situation and development of solar heating technology in China

    Institute of Scientific and Technical Information of China (English)

    Zheng Ruicheng

    2009-01-01

    It is introduced the current situation and development for solar heating technology including passive solar heat-ing and solar heating combisystems in China in this paper. Combined with the engineering application projects, the au-thor gave the technical and economic analysis of the passive solar and solar heating combisystems in China and summa-rized the developing obstacle and the spreading tactics for raising marketing of the solar heating in China.

  10. The Sun's interior structure and dynamics, and the solar cycle

    CERN Document Server

    Broomhall, A -M; Howe, R; Norton, A A; Thompson, M J

    2014-01-01

    The Sun's internal structure and dynamics can be studied with helioseismology, which uses the Sun's natural acoustic oscillations to build up a profile of the solar interior. We discuss how solar acoustic oscillations are affected by the Sun's magnetic field. Careful observations of these effects can be inverted to determine the variations in the structure and dynamics of the Sun's interior as the solar cycle progresses. Observed variations in the structure and dynamics can then be used to inform models of the solar dynamo, which are crucial to our understanding of how the Sun's magnetic field is generated and maintained.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, N. B.; Kong, D. F., E-mail: nanbin@ynao.ac.cn [National Astronomical Observatories/Yunnan Observatory, CAS, Kunming 650011 (China)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, Simon J. [School of Engineering, University of Bradford, Bradford, BD7 1DP (United Kingdom); Zharkov, Sergei I. [Department of Physics and Mathematics, University of Hull, Kingston upon Tyne, HU6 7RS (United Kingdom); Zharkova, Valentina V., E-mail: s.j.shepherd@brad.ac.uk, E-mail: s.zharkov@hull.ac.uk, E-mail: valentina.zharkova@northumbria.ac.uk [Department of Mathematics and Information Systems, University of Northumbria, Newcastle upon Tyne, NE2 8ST (United Kingdom)

    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.

  13. Imprints from the solar cycle on the helium atom and helium pickup ion distributions

    Directory of Open Access Journals (Sweden)

    D. Rucinski

    Full Text Available Neutral interstellar helium atoms penetrate into the solar system almost unaffected by gas–plasma interactions in the heliospheric interface region, and thus can be considered as carriers of original information on the basic parameters (like density, temperature, bulk velocity of the Very Local Interstellar Medium (VLISM. Such information can nowadays be derived from analysis of data obtained from different experimental methods: in situ measurements of He atoms (Ulysses, observations of the solar backscattered He 584 A radiation (EUVE, in situ measurements of He + pickup ions (AMPTE, Ulysses, Wind, SOHO, ACE. In view of the current coordinated international ISSI campaign devoted to the study of the helium focusing cone structure and its evolution, we analyze expected variations of neutral He density, of He + pickup fluxes and of their phase space distributions at various phases of the solar activity cycle based on a realistic time-dependent modelling of the neutral helium and He + pickup ion distributions, which reflect solar cycle-induced variations of the photoionization rate. We show that the neutral helium density values are generally anticorrelated with the solar activity phase and in extreme cases (near the downwind axis the maximum-to-minimum density ratio may even exceed factors of ~ 3 at 1 AU. We also demonstrate that in the upwind hemisphere (at 1 AU and beyond the He + fluxes are correlated with the solar cycle activity, whereas on the downwind side the maximum of the expected flux up to distances of ~ 3 AU occurs around solar minimum epoch, and only further away does the correlation with solar activity become positive. Finally, we present the response of the phase space distribution spectra of He + pickup ions (in the solar wind frame for different epochs of the solar cycle and heliocentric distances from 1 to 5 AU covering the range of Ulysses, Wind and ACE observations.

    Key words. Solar physics, astrophysics and astronomy

  14. Comparing the Large-Scale Magnetic Field During the Last Three Solar Cycles (Invited)

    Science.gov (United States)

    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.

  15. Stratosphere-troposphere coupling and the solar cycle

    Science.gov (United States)

    Black, R.; Whitesides, B.

    There is a surprisingly large amount of tropospheric climate variability that is linked to the solar cycle. This signal is manifested by annular temperature and wind anomaly structures in both the troposphere and stratosphere. The relatively strong variability in UV radiation observed during the solar cycle has focused attention on the impact of the solar cycle upon the stratosphere. This idea is confirmed in modeling studies which also indicate a climate response extending into the troposphere. Better knowledge of the dynamic linkages between the middle and lower atmosphere is essential in pursuing a mechanistic understanding of solar cycle-climate linkages. An overview is first provided of the key mechanisms that dynamically couple the stratosphere and troposphere. The direct and indirect means by which the stratosphere can influence tropospheric climate are emphasized. Direct downward influences include tropospheric circulation changes induced by latitudinal redistributions of mass and potential vorticity within the stratosphere. Indirect influences involve alterations in the vertical and meridional propagation of tropospheric Rossby waves, which in turn provide local wave forcings to the longitudinally averaged wind field. A statistical and diagnostic framework is then introduced for studying the dynamic coupling between the stratosphere and troposphere in association with the solar cycle. We hypothesize that the solar cycle provides dynamical influences to the tropospheric circulation via variations in the strength of the wintertime stratospheric polar vortex. Synoptic and dynamic atmospheric circulation structures linked to the solar cycle are first isolated using multivariate statistical analyses. Diagnostic analyses are then performed to answer the following questions: What are the relative importance of stratospheric and tropospheric dynamic structures in comprising tropospheric circulation anomalies? How do the propagation characteristics of tropospheric

  16. Connection between solar activity cycles and grand minima generation

    Science.gov (United States)

    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.

  17. Prediction of solar cycle based on the invariant

    Institute of Scientific and Technical Information of China (English)

    LIU Shijun; YU Xiaoding; CHEN Yongyi

    2003-01-01

    A new method of predicting solar activities has been introduced in this paper. The method can predict both the occurrence time and the maximum number of sunspot at the same time. By studying the variation of sunspot, we find that the combination of the several variables was nearly invariable during the entire solar cycles, as called invariant. And just only by determining the start time of a cycle, we can predict the occurrence time of cycle's peak value accurately. Furthermore, according to observational data of the sunspot cycles, it showed that the sunspot maximum number has correlation not only with the prophase variety of the number in the cycle but also with the anaphase of the previous period. So we can introduce an equivalent regression coefficient, which can dynamically self-adapt to different cycle lengths, and effectively solve the inconsistency between the accuracy and the lead-time of the forecast. It can guarantee the satisfied accuracy and effectively increases the lead-time of the forecast. This method can predict the maximum sunspot number for solar cycle at the approximate half rise of the period. This method predicts that the occurrence time of the maximum sunspot number for cycle 24 will be in January 2011.

  18. Selected solar wind parameters at 1 AU through two solar activity cycles

    Directory of Open Access Journals (Sweden)

    R. Bruno

    Full Text Available In situ measurements of the solar wind largely cover more than two solar magnetic activity cycles, namely 20 and 21. This is a very appealing opportunity to study the influence of the activity cycle on the behaviour of the solar wind parameters. As a matter of fact, many authors so far have studied this topic comparing the long-term magnetic field and plasma averages. However, when the average values are evaluated on a data sample whose duration is comparable with (or even longer than the solar rotation period we lose information about the contribution due to the fast and the slow solar wind components. Thus, discriminating in velocity plays a key role in understanding solar cycle effects on the solar wind. Based on these considerations, we performed a separate analysis for fast and slow wind, respectively. In particular, we found that: (a fast wind carries a slightly larger momentum flux density at 1 AU, probably due to dynamic stream-stream interaction; (b proton number density in slow wind is more cycle dependent than in fast wind and decreases remarkably across solar maximum; (c fast wind generally carries a magnetic field intensity stronger than that carried by the slow wind; (d we found no evidence for a positive correlation between velocity and field intensity as predicted by some theories of solar wind acceleration; (e our results would support an approximately constant divergence of field lines associated with corotating high-velocity streams.

  19. Models of Solar Irradiance Variations: Current Status

    Indian Academy of Sciences (India)

    Natalie A. Krivova; Sami K. Solanki

    2008-03-01

    Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the solar surface magnetic field. Here the most recent advances in modelling of solar irradiance variations on time scales longer than a day are briefly reviewed.

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

    Science.gov (United States)

    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

  1. Performance evaluation of space solar Brayton cycle power systems

    Science.gov (United States)

    Diao, Zheng-Gang

    1992-06-01

    Unlike gas turbine power systems which consume chemical or nuclear energy, the energy consumption and/or cycle efficiency should not be a suitable criterion for evaluating the performance of space solar Brayton cycle power. A new design goal, life cycle cost, can combine all the power system characteristics, such as mass, area, and station-keeping propellant, into a unified criterion. Effects of pressure ratio, recuperator effectiveness, and compressor inlet temperature on life cycle cost were examined. This method would aid in making design choices for a space power system.

  2. Radio Imaging Observations of Solar Activity Cycle and Its Anomaly

    Science.gov (United States)

    Shibasaki, K.

    2011-12-01

    The 24th solar activity cycle has started and relative sunspot numbers are increasing. However, their rate of increase is rather slow compared to previous cycles. Active region sizes are small, lifetime is short, and big (X-class) flares are rare so far. We study this anomalous situation using data from Nobeyama Radioheliograph (NoRH). Radio imaging observations have been done by NoRH since 1992. Nearly 20 years of daily radio images of the Sun at 17 GHz are used to synthesize a radio butterfly diagram. Due to stable operation of the instrument and a robust calibration method, uniform datasets are available covering the whole period of observation. The radio butterfly diagram shows bright features corresponding to active region belts and their migration toward low latitude as the solar cycle progresses. In the present solar activity cycle (24), increase of radio brightness is delayed and slow. There are also bright features around both poles (polar brightening). Their brightness show solar cycle dependence but peaks around solar minimum. Comparison between the last minimum and the previous one shows decrease of its brightness. This corresponds to weakening of polar magnetic field activity between them. In the northern pole, polar brightening is already weakened in 2011, which means it is close to solar maximum in the northern hemisphere. Southern pole does not show such feature yet. Slow rise of activity in active region belt, weakening of polar activity during the minimum, and large north-south asymmetry in polar activity imply that global solar activity and its synchronization are weakening.

  3. Solar neutron decay proton observations in cycle 21

    Science.gov (United States)

    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.

  4. Second law analysis of a solar powered Rankine cycle/vapor compression cycle

    Energy Technology Data Exchange (ETDEWEB)

    Egrican, A.N.; Karakas, A.

    1986-01-01

    Conversion of solar heat energy to power or air conditioning is a difficult and costly process. Only two practical means of solar cooling are presently state-of-the-art. These are by use of the Rankine cycle/vapor compression cycle (RC/VCC) and the absorption refrigeration cycle. RC/VCC solar cooling systems convert collected solar heat into a cooling effect. In the present study, the second law analysis is given, the maximum reversible work, lost work and availability for each component are calculated. The use of lost work or irreversibility and availability analysis in a real thermodynamic and heat transfer problem is very important in at least two regards. The first one is that in most cases accomplishing a real problem with the less irreversibility is directly proportional to the less cost. The second one is that availability is one of our natural resources. The conservation and effective use of availability reserves result in the decrease irreversibilities.

  5. Forecast of the key parameters of the 24-th solar cycle

    Institute of Scientific and Technical Information of China (English)

    Oleg Vasilievich Chumak; Tatiana Viktorovna Matveychuk

    2010-01-01

    To predict the key parameters of the solar cycle,a new method is proposed based on the empirical law describing the correlation between the maximum height of the preceding solar cycle and the entropy of the forthcoming one.The entropy of the forthcoming cycle may be estimated using this empirical law,if the maximum height of the current cycle is known.The cycle entropy is shown to correlate well with the cycle's maximum height and,as a consequence,the height of the forthcoming maximum can be estimated.In turn,the correlation found between the height of the maximum and the duration of the ascending branch(the Waldmeier rule)allows the epoch of the maximum,Tmax,to be estimated,if the date of the minimum is known.Moreover,using the law discovered,one can find out the analogous cycles which are similar to the cycle being forecasted,and hence,obtain the synoptic forecast of all main features of the forthcoming cycle.The estimates have shown the accuracy level of this technique to be 86%.The new regularities discovered are also interesting because they are fundamental in the theory of solar cycles and may provide new empirical data.The main parameters of the future solar cycle 24 are as follows: the height of the maximum is Wmax = 95±20,the duration of the ascending branch is Ta = 4.5±0.5 yr,the total cycle duration according to the synoptic forecast is 11.3 yr.

  6. Investigating the Causes of Solar-Cycle Variations in Solar Energetic Particle Fluences and Composition

    Science.gov (United States)

    Mewaldt, Richard; Cohen, Christina; Mason, Glenn M.; von Rosenvinge, Tycho; Li, Gang; Smith, Charles; Vourlidas, Angelos

    2015-04-01

    Measurements with ACE, STEREO, and GOES show that the number of large Solar Energetic Particle (SEP) events in solar cycle 24 is reduced by a factor of ~2 compared to this point of cycle 23, while the fluences of >10 MeV/nuc ions from H to Fe are reduced by factors ranging from ~4 to ~10. We investigate the origin of these cycle-to-cycle differences by evaluating possible factors that include properties of the associated CMEs, seed particle densities, and the interplanetary magnetic field strength and turbulence levels. These properties will be evaluated in the context of existing SEP acceleration models.

  7. High solar cycle spectral variations inconsistent with stratospheric ozone observations

    CERN Document Server

    Ball, W T; Rozanov, E V; Kuchar, A; Sukhodolov, T; Tummon, F; Shapiro, A V; Schmutz, W

    2016-01-01

    Some of the natural variability in climate is understood to come from changes in the Sun. A key route whereby the Sun may influence surface climate is initiated in the tropical stratosphere by the absorption of solar ultraviolet (UV) radiation by ozone, leading to a modification of the temperature and wind structures and consequently to the surface through changes in wave propagation and circulation. While changes in total, spectrally-integrated, solar irradiance lead to small variations in global mean surface temperature, the `top-down' UV effect preferentially influences on regional scales at mid-to-high latitudes with, in particular, a solar signal noted in the North Atlantic Oscillation (NAO). The amplitude of the UV variability is fundamental in determining the magnitude of the climate response but understanding of the UV variations has been challenged recently by measurements from the SOlar Radiation and Climate Experiment (SORCE) satellite, which show UV solar cycle changes up to 10 times larger than p...

  8. The NASA's Long-Term Global Solar Energy Resource: Current Solar Resource Variability and Future Improvements

    Science.gov (United States)

    Stackhouse, P. W.; Cox, S. J.; Zhang, T.; Chandler, W.; Westberg, D.; Hoell, J. M.

    2011-12-01

    Considering the likelihood of global climate change and the global competition for energy resources, there is an increasing need to provide improved global Earth surface solar resource information. The improved long-term records are needed to better understand and quantify potential shifts in the solar resource with anticipated changes in climatic weather patterns. As part of the World Climate Research Programme's (WCRP) Global Energy and Water Cycle Experiment (GEWEX), NASA has an active Surface Radiation Budget project that has produced long-term global gridded estimates of the surface solar fluxes. These fluxes have been processed and made available to the solar energy community over the years through NASA's Surface meteorology and Solar Energy web site (SSE). This web site provides solar resource and accompanying meteorological variables specifically tailored to the renewable energy community spanning a 22 year period. The web application has been improved over time with usage growing nearly exponentially over the last few years. This paper presents the global and regional variability of the solar resource from the current data available at the SSE web application. The variability is compared for large different spatial scales and compared to other data sets where appropriate. We assess the interannual variability compared against surface sites and other satellite based data sets. These comparisons quantify the limits of usefulness of this data set. For instance, we find long-term linear trends that are dominated by satellite based artifacts in some areas, but agree well with surface measurements in others. Nevertheless, the extremes of solar variability are quantified and show agreement with surface observations good enough for most feasibility studies of solar energy systems. This presentation also contains a description of work currently on going to replace the current solar resource information available on SSE with a completely reprocessed version. The

  9. Mechanism of Cyclically Polarity Reversing Solar Magnetic Cycle as a Cosmic Dynamo

    Indian Academy of Sciences (India)

    Hirokazu Yoshimura

    2000-09-01

    We briefly describe historical development of the concept of solar dynamo mechanism that generates electric current and magnetic field by plasma flows inside the solar convection zone. The dynamo is the driver of the cyclically polarity reversing solar magnetic cycle. The reversal process can easily and visually be understood in terms of magnetic field line stretching and twisting and folding in three-dimensional space by plasma flows of differential rotation and global convection under influence of Coriolis force. This process gives rise to formation of a series of huge magnetic flux tubes that propagate along iso-rotation surfaces inside the convection zone. Each of these flux tubes produces one solar cycle. We discuss general characteristics of any plasma flows that can generate magnetic field and reverse the polarity of the magnetic field in a rotating body in the Universe. We also mention a list of problems which are currently being disputed concerning the solar dynamo mechanism together with observational evidences that are to be constraints as well as verifications of any solar cycle dynamo theories of short and long term behaviors of the Sun, particularly time variations of its magnetic field, plasma flows, and luminosity.

  10. Advanced power cycles and configurations for solar towers: Modeling and optimization of the decoupled solar combined cycle concept

    Science.gov (United States)

    García-Barberena, Javier; Olcoz, Asier; Sorbet, Fco. Javier

    2017-06-01

    CSP technologies are essential to allow large shares of renewables into the grid due to their unique ability to cope with the large variability of the energy resource by means of technically and economically feasible thermal energy storage (TES) systems. However, there is still the need and sought to achieve technological breakthroughs towards cost reductions and increased efficiencies. For this, research on advanced power cycles, like the Decoupled Solar Combined Cycle (DSCC) is, are regarded as a key objective. The DSCC concept is, basically, a Combined Brayton-Rankine cycle in which the bottoming cycle is decoupled from the operation of the topping cycle by means of an intermediate storage system. According to this concept, one or several solar towers driving a solar air receiver and a Gas Turbine (Brayton cycle) feed through their exhaust gasses a single storage system and bottoming cycle. This general concept benefits from a large flexibility in its design. On the one hand, different possible schemes related to number and configuration of solar towers, storage systems media and configuration, bottoming cycles, etc. are possible. On the other, within a specific scheme a large number of design parameters can be optimized, including the solar field size, the operating temperatures and pressures of the receiver, the power of the Brayton and Rankine cycles, the storage capacity and others. Heretofore, DSCC plants have been analyzed by means of simple steady-state models with pre-stablished operating parameters in the power cycles. In this work, a detailed transient simulation model for DSCC plants has been developed and is used to analyze different DSCC plant schemes. For each of the analyzed plant schemes, a sensitivity analysis and selection of the main design parameters is carried out. Results show that an increase in annual solar to electric efficiency of 30% (from 12.91 to 16.78) can be achieved by using two bottoming Rankine cycles at two different

  11. Current Comparison of Advanced Nuclear Fuel Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Steven Piet; Trond Bjornard; Brent Dixon; Robert Hill; Gretchen Matthern; David Shropshire

    2007-04-01

    This paper compares potential nuclear fuel cycle strategies – once-through, recycling in thermal reactors, sustained recycle with a mix of thermal and fast reactors, and sustained recycle with fast reactors. Initiation of recycle starts the draw-down of weapons-usable material and starts accruing improvements for geologic repositories and energy sustainability. It reduces the motivation to search for potential second geologic repository sites. Recycle in thermal-spectru

  12. Current Status and Advancements in Research of Plantation Nutrient Cycling

    Institute of Scientific and Technical Information of China (English)

    LI Run; ZHANG Changshun; SUN Yongyu

    2006-01-01

    This paper introduces concepts and current research status of plantation nutrients cyclings, and analyzes main contents of plantation nutrients cycling as nutrients contents, accumulation and distribution of nutrients elements, understory species and forest litter. At the same time, the paper summarizes the problems in plantation nutrients cycling and its prospects.

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

    Science.gov (United States)

    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.

  14. Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

    Science.gov (United States)

    Park, Keunchan; Lee, Jeongwoo; Yi, Yu; Lee, Jaejin; Sohn, Jongdae

    2017-06-01

    Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed 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. We also calculate two pressures (magnetic, dynamic) and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME). We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

  15. Exergy analysis of an integrated solar combined cycle system

    Energy Technology Data Exchange (ETDEWEB)

    Baghernejad, A.; Yaghoubi, M. [Engineering School, Shiraz University, Shiraz (Iran)

    2010-10-15

    Exergetic analysis has become an integral part of thermodynamic assessment of any power generation system. Energy and exergy studies for power plants optimum design and for combined chemical industries received much attention recently. An Integrated Solar Combined Cycle System (ISCCS) is proposed as a means of integrating a parabolic trough solar thermal plant with modern combined cycle power plants. In this study attempt will be made to analyze the Integrated Solar Combined Cycle in Yazd, Iran using design plant data. Energy and exergy analysis for the solar field and combined cycle is carried out to assess the plant performance and pinpoint sites of primary exergy destruction. Exergy destruction throughout the plant is quantified and illustrated using an exergy flow diagram, and compared to the energy flow diagram. The causes of exergy destruction in the plant include: losses in combustor, collector, heat exchangers, and pump and turbines which accounts for 29.62, 8.69, 9.11 and 8% of the total exergy input to the plant, respectively. Exergetic efficiencies of the major plant components are determined in an attempt to assess their individual performances. (author)

  16. Refined life-cycle assessment of polymer solar cells

    DEFF Research Database (Denmark)

    Lenzmann, F.; Kroon, J.; Andriessen, R.

    2011-01-01

    A refined life-cycle assessment of polymer solar cells is presented with a focus on critical components, i.e. the transparent conductive ITO layer and the encapsulation components. This present analysis gives a comprehensive sketch of the full environmental potential of polymer-OPV in comparison...

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

    Directory of Open Access Journals (Sweden)

    Edward Valachovic

    2014-01-01

    Full Text Available 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.

  18. Does a low solar cycle minimum hint at a weak upcoming cycle?

    Institute of Scientific and Technical Information of China (English)

    Zhan-Le Du; Hua-Ning Wang

    2010-01-01

    The maximum amplitude (Rm) of a solar cycle, in the term of mean sunspot numbers, is well-known to be positively correlated with the preceding minimum (Rmin). So far as the long term trend is concerned, a low level of Rmin tends to be followed by a weak Rm, and vice versa. We found that the evidence is insufficient to infer a very weak Cycle 24 from the very low Rmin in the preceding cycle. This is concluded by analyzing the correlation in the temporal variations of parameters for two successive cycles.

  19. Paleoclimate forcing by the solar De Vries/Suess cycle

    Directory of Open Access Journals (Sweden)

    H.-J. Lüdecke

    2015-02-01

    Full Text Available A large number of investigations of paleoclimate have noted the influence of a ~ 200 year oscillation which has been related to the De Vries/Suess cycle of solar activity. As such studies were concerned mostly with local climate, we have used extensive northern hemispheric proxy data sets of Büntgen and of Christiansen/Ljungqvist together with a southern hemispheric tree-ring set, all with 1 year time resolution, to analyze the climate influence of the solar cycle. As there is increasing interest in temperature rise rates, as opposed to present absolute temperatures, we have analyzed temperature differences over 100 years to shed light on climate dynamics of at least the last 2500 years. Fourier- and Wavelet transforms as well as nonlinear optimization to sine functions show the dominance of the ∼ 200 year cycle. The sine wave character of the climate oscillations permits an approximate prediction of the near future climate.

  20. The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles

    CERN Document Server

    Aschwanden, Markus J

    2010-01-01

    We analyze the occurrence frequency distributions of peak fluxes $P$, total fluxes $E$, and durations $T$ of solar flares over the last three solar cycles (during 1980-2010) from hard X-ray data of HXRBS/SMM, BATSE/CGRO, and RHESSI. From the synthesized data we find powerlaw slopes with mean values of $\\alpha_P=1.75\\pm0.05$ for the peak flux, $\\alpha_E=1.61\\pm0.04$ for the total flux, and $\\alpha_T=2.08\\pm0.10$ for flare durations. We find no evidence that these frequency distributions have significantly different slopes during the minima of the solar cycles, including the current anomalously extended solar minimum. The powerlaw distributions can be interpreted in terms of a nonlinear dissipative system in the state of self-organized criticality (SOC). The invariance of the powerlaw slopes during the solar cycles, despite of the nonstationarity of the flare rate by orders of magnitude, implies a universal behavior in the nonlinear growth evolution of magnetic instabilities in solar flares, independent of a sl...

  1. Solar Magnetic Field and the Mass Egections during CYCLE23

    Science.gov (United States)

    Abdhady, Ahmed; Shaltout, Mosalam

    The solar cycle 23 started in 1996 and its maximum was in May 2001. More than ten high energic flares (Proton flares) occurred from solar active region’s of large and complex magnetic fields of strength 2500 to 3000 gauss. The mass ejection measured by artificial satellites for proton of energies more than 10 Mev. The increased of the solar wind in velocity and density which occurred after the releasing of the solar eruptive flares was measured by artificial satellites. The geomagnetic storms and the sudden ionospheric disturbance measured by ground stations. The used data will be world-wide solar-geophysical data as that of NOAA USA and Bejin observatory China. The results lead to important role of the local magnetic field of the solar active region in production of high-energetic solar flares and its effect on the electromagnetic component and dynamic component of the flare. The effect of the magnetic field on the three different phase of the eruptive flare were given (thermal phase impulsive phase and recovery phase). Our results in this study may be help in flare prediction and mass ejection estimation before its reach to the earth and produce geomagnetic storms.

  2. Simulating and Predicting Solar Cycles Using a Flux-Transport Dynamo

    Science.gov (United States)

    Dikpati, Mausumi; Gilman, Peter A.

    2006-09-01

    We construct a predictive tool based on a Babcock-Leighton-type flux-transport dynamo model of a solar cycle, run the model by updating the surface magnetic source using old cycles' data since cycle 12, and show that the model can correctly simulate the relative peaks of cycles 16-23. The simulations use the first four cycles to load the meridional circulation conveyor belt to create the Sun's memory about its past magnetic fields. Extending the simulation into the future, we predict that cycle 24 will be 30%-50% stronger than the current cycle 23. These simulations and predictions are robust for a wide range of convection zone magnetic diffusivity values between 3×1010 and 2×1011 cm2 s-1. Our model predictions are the same for three different treatments of the unknown surface magnetic source for the cycles to be predicted, namely (1) assuming some cyclic pattern, (2) incorporating ``zero'' surface source, or (3) including a surface source derived from the self-excited version of the dynamo model. Technique 3, for treating the surface source for cycles to be predicted, also shows significant skill in predicting two cycles ahead. Analyzing the evolution of magnetic field patterns over a full magnetic cycle, we show that the key to success of our prediction model lies in the formation of a ``seed'' for producing cycle n from the combination of latitudinal fields at high latitudes from three past cycles, n-1, n-2, and n-3, instead of the previous cycle's polar fields. These results have many implications for both solar and stellar dynamo modeling.

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

    Science.gov (United States)

    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.

  4. Statistical properties of solar flares and coronal mass ejections through the solar cycle

    Energy Technology Data Exchange (ETDEWEB)

    Telloni, Daniele; Antonucci, Ester [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy); Carbone, Vincenzo [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy); CNR-Institute for Chemical-Physical Processes, Ponte P. Bucci Cubo 33B, 87036 Rende (Italy); Lepreti, Fabio [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy)

    2016-03-25

    Waiting Time Distributions (WTDs) of solar flares are investigated all through the solar cycle. The same approach applied to Coronal Mass Ejections (CMEs) in a previous work is considered here for flare occurrence. Our analysis reveals that flares and CMEs share some common statistical properties, which result dependent on the level of solar activity. Both flares and CMEs seem to independently occur during minimum solar activity phases, whilst their WTDs significantly deviate from a Poisson function at solar maximum, thus suggesting that these events are correlated. The characteristics of WTDs are constrained by the physical processes generating those eruptions associated with flares and CMEs. A scenario may be drawn in which different mechanisms are actively at work during different phases of the solar cycle. Stochastic processes, most likely related to random magnetic reconnections of the field lines, seem to play a key role during solar minimum periods. On the other hand, persistent processes, like sympathetic eruptions associated to the variability of the photospheric magnetism, are suggested to dominate during periods of high solar activity. Moreover, despite the similar statistical properties shown by flares and CMEs, as it was mentioned above, their WTDs appear different in some aspects. During solar minimum periods, the flare occurrence randomness seems to be more evident than for CMEs. Those persistent mechanisms generating interdependent events during maximum periods of solar activity can be suggested to play a more important role for CMEs than for flares, thus mitigating the competitive action of the random processes, which seem instead strong enough to weaken the correlations among flare event occurrence during solar minimum periods. However, it cannot be excluded that the physical processes at the basis of the origin of the temporal correlation between solar events are different for flares and CMEs, or that, more likely, more sophisticated effects are

  5. Pluto's Haze from 2002 - 2015: Correlation with the Solar Cycle

    Science.gov (United States)

    Young, Eliot; Klein, Viliam; Hartig, Kara; Resnick, Aaron; Mackie, Jason; Carriazo, Carolina; Watson, Charles; Skrutskie, Michael; Verbiscer, Anne; Nelson, Matthew; Howell, Robert; Wasserman, Lawrence; Hudson, Gordon; Gault, David; Barry, Tony; Sicardy, Bruno; Cole, Andrew; Giles, Barry; Hill, Kym

    2017-04-01

    Occultations by Pluto were observed 2002, 2007, 2011 and 2015, with each event observed simultaneously in two or more wavelengths. Separate wavelengths allow us to discriminate between haze opacity and refractive effects due to an atmosphere's thermal profile - these two effects are notoriously hard to separate if only single-wavelength lightcurves are available. Of those four occultations, the amount of haze in Pluto's atmosphere was highest in 2002 (Elliot et al. 2003 report an optical depth of 0.11 at 0.73 µm in the zenith direction), but undetectable in the 2007 and 2011 events (we find optical depth upper limits of 0.012 and 0.010 at 0.6 µm). Cheng et al. (2016) report a zenith optical depth of 0.018 at 0.6 µm from the haze profiles seen in New Horizons images. These four data points are correlated with the solar cycle. The 2002 haze detection occurred just after the peak of solar cycle 23, the 2007 and 2011 non-detections occurred during the solar minimum between peaks 23 and 24, and the New Horizons flyby took place just after the peak of solar cycle 24. This suggests that haze production on Pluto (a) is driven by solar UV photons or charged particles, (b) that sources and sinks on Pluto have timescales shorter than a few Earth years, and (c) the haze precursors on Pluto are not produced by Lyman-alpha radiation, because Lyman-alpha output only decreased by about one third in between the cycle 23 and 24 peaks, much less than the observed change in Pluto's haze abundances. References: Elliot, J.L. et al. (2003) Nature, Volume 424, Issue 6945, pp. 165-168.

  6. Durability Study of SOFCs Under Cycling Current Load Conditions

    DEFF Research Database (Denmark)

    Hagen, Anke; Hendriksen, Peter Vang; Frandsen, Henrik Lund;

    2009-01-01

    In fuel cell applications, the cells must be able to withstand varying operating conditions. Anode supported solid oxide fuel cells were tested under cycling current load in order to determine the durability and possibly identify degradation mechanisms. At 750 °C and a cycling between zero and 0.......75 A cm-2, the cell voltage degradation rate was similar to tests with the corresponding high constant current density. However, by analyzing the impedance spectra it was found that anode degradation was becoming more important when going from constant to cycling conditions. Running the cycling load tests...... at 850 °C, the cells degraded similarly as under the corresponding constant current load whereas, in some cases, cells failed mechanically after a few hundred hours. These cells did not experience severe additional degradation due to the cycling of the current density until the point of failure...

  7. Thermoeconomic Evaluation of Integrated Solar Combined Cycle Systems (ISCCS

    Directory of Open Access Journals (Sweden)

    Javier Rodríguez Martín

    2014-07-01

    Full Text Available Three alternatives for integrating a solar field with the bottoming cycle of a combined cycle plant are modeled: parabolic troughs with oil at intermediate and low cycle pressures and Fresnel linear collectors at low cycle pressure. It is assumed that the plant will always operate at nominal conditions, using post-combustion during the hours of no solar resource. A thermoeconomic study of the operation of the plant throughout a year has been carried out. The energy and exergy efficiencies of the plant working in fuel only and hybrid modes are compared. The energy efficiencies obtained are very similar; slightly better for the fuel only mode. The exergy efficiencies are slightly better for hybrid operation than for fuel-only mode, due to the high exergy destruction associated with post-combustion. The values for solar electric efficiency are in line with those of similar studies. The economic study shows that the Fresnel hybridization alternative offers similar performance to the others at a significantly lower cost.

  8. Solar Cycle Phase Dependence of Supergranular Fractal Dimension

    Indian Academy of Sciences (India)

    U. Paniveni; V. Krishan; J. Singh; R. Srikanth

    2011-03-01

    We study the complexity of supergranular cells using the intensity patterns obtained from the Kodaikanal Solar Observatory during the 23rd solar cycle. Our data consists of visually identified supergranular cells, from which a fractal dimension for supergranulation is obtained according to the relation ∝ /2, where is the area and is the perimeter of the supergranular cells. We find a difference in the fractal dimension between active and quiet region cells in the ascending phase, during the peak and in the descending phase which is conjectured to be due to the magnetic activity level.

  9. Solar Cycle Variation and Multipoint Studies of ICME Properties

    Science.gov (United States)

    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.

  10. A brief review on the presentation of cycle 24, the first integrated solar cycle in the new millennium

    Directory of Open Access Journals (Sweden)

    K. J. Li

    2011-02-01

    Full Text Available The status of the extended solar activity minimum, since the second half of 2007, has been briefly instructed to the solar-terrestrial community. Cycle 24 has the most spotless days since cycle 16, and probably even since the modern cycles, latitudes of high-latitude (>35° sunspots belonging to a new cycle around the minimum time of the cycle are statistically the lowest at present, compared with those of cycle 12 onwards, and there is only one or no sunspots in a month appearing at high latitudes (>20° for 58 months (from November 2003 to September 2008, which is observed for the first time since cycle 12 onwards. The solar wind velocity and pressure, 10.7 cm solar radio flux, the polar solar magnetic field, solar total irradiance, and so on reach their minima during the 23–24 cycle minimum time. In order to explain the present extreme low activity, we introduced here one possible mechanism using helio-seismology observations. Viewing, from the long-term running of the time scales of both the Gleissberg period and millenniums, the extended solar activity minimum becomes logical. According to the present observations, the cycle 24 should start in November 2008. Solar activity is predicted at being about 30% lower in cycle 24 than in cycle 23, synthesizing the typical predictions of solar activity, including those given by NASA and NOAA. The 24th solar cycle is sluggishly coming and it should be an opportune moment for studying solar physics and solar-terrestrial physics.

  11. The Venus Atmospheric Response to Solar Cycle Variations

    Science.gov (United States)

    Keating, Gerald M.; Hsu, N. Christina

    1993-01-01

    Atmospheric drag measurements from the orbital decay of the Pioneer Venus Orbiter and Magellan spacecraft have recently been obtained of the Venus dayside and nightside atmosphere between 130 and 210 km during a period of low solar activity. These new measurements, combined with the earlier Pioneer Venus drag measurements (1978-80) obtained near the maximum of the 11-year solar cycle, have allowed the detection of the detailed response of temperature, atomic oxygen and carbon dioxide to solar variations. We have found a weak but detectable temperature response on the dayside which is in accord with the response predicted by Keating and Bougher when they assumed very strong CO2 radiative cooling resulting from atomic oxygen exciting CO2 into 15 micron emission. This same radiative process may cause strong cooling in the Earth's upper atmosphere with the doubling of CO2 in the future. With decreasing solar activity, the O/CO2 ratio in the lower thermosphere is found to decrease, apparently due to decreased photodissociation of CO2 and lower temperatures. The percent decrease in atomic oxygen with decreasing solar activity on the dayside is found to be approximately the same as the percent decreases of atomic oxygen transported to the nightside. A very weak response of nightside temperatures to solar activity variations has also been detected.

  12. Thermochemical cycles based on metal oxides for solar hydrogen production; Ciclos termoquimicos basados en oxidos metalicos para produccion de hidrogeno solar

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.; Quejido Cabezas, J.

    2012-11-01

    The growing demand for energy requires the development and optimization of alternative energy sources. One of the options currently being investigated is solar hydrogen production with thermochemical cycles. This process involves the use of concentrated solar radiation as an energy source to dissociate water through a series of endothermic and exothermic chemical reactions, for the purpose of obtaining hydrogen on a sustainable basis. Of all the thermochemical cycles that have been evaluated, the most suitable ones for implementation with solar energy are those based on metal oxides. (Author) 20 refs.

  13. The Influence of The Solar-cycle Induced Solar Wind Variations

    Science.gov (United States)

    Fahr, H.-J.; Scherer, K.

    In the course of the solar activity cycle both the solar wind velocity and density un- dergo quasi-sinusoidal variations. These longperiodic variations propagate outwards through the interplanetary space for over a year until they finally reach the heliospheric termination shock. The associated variation of the solar wind ram pressure not only influences there the stand-off distance of the termination shock, but also changes the production and the heliospheric distribution of pick-up ions (PUIs). As a consequence, also the production of anomalous cosmic rays (ACRs) related to PUI-fluxes arriving at the shock varies, the propagation of ACRs is influenced and the modulation of the galactic cosmic rays strongly differs. To quantitatively study this scenario we use a a multi-fluid hydrodynamic simulation code to model the interaction of the solar-cycle modulated heliosphere with the interstellar medium. In this code all dynamically rel- evant species are described by separate plasma fluids within a consistent multifluid context. In a first step we describe the solar-cycle induced heliospheric variations by a series of static models, i.e. we discretizised the solar cycle variation of the SW param- eters and let each model for a selected set of SW parameters deliver an asymptotically stable state. Then we restart this procedure for the next set of SW parameters. The ob- tained set of different heliosphere configurations is then taken as envelopping a fully time-dependent model, in which the solar-cycle varying SW parameters are modeled on the basis of actually time-dependent variations. Here we present the results of the static model runs with emphasis on PUI, ACR and GCR distributions. We also will discuss first results of the time-dependent model.

  14. Solar Cycle Length and Northern Hemisphere mean temperature revisited.

    Science.gov (United States)

    Thejll, P.

    2009-04-01

    The statistical relationship between the smoothed curve for solar cycle length and northern hemisphere land mean temperature has been a source of investigation in the question of whether and how much the Sun influences climate variations. The relationship was widely discussed following the 1991 paper by Friis-Christensen and Lassen and was updated in 2000 by Thejll and Lassen. Data for one more solar cycle has now accumulated, and the relationship is again reviewed and discussed. We derive and show the updated SCL and mean temperature curves. The relationship between the two is analysed using standard statistical methods. Additional climate forcing factors are introduced to improve the fit. Changes in the historical part of the mean temperature curve has occurred which modifies the previously seen relationship, and this is discussed.

  15. The South Atlantic Anomaly throughout the solar cycle

    Science.gov (United States)

    Domingos, João; Jault, Dominique; Pais, Maria Alexandra; Mandea, Mioara

    2017-09-01

    The Sun-Earth's interaction is characterized by a highly dynamic electromagnetic environment, in which the magnetic field produced in the Earth's core plays an important role. One of the striking characteristics of the present geomagnetic field is denoted the South Atlantic Anomaly (SAA) where the total field intensity is unusually low and the flux of charged particles, trapped in the inner Van Allen radiation belts, is maximum. Here, we use, on one hand, a recent geomagnetic field model, CHAOS-6, and on the other hand, data provided by different platforms (satellites orbiting the Earth - POES NOAA for 1998-2014 and CALIPSO for 2006-2014). Evolution of the SAA particle flux can be seen as the result of two main effects, the secular variation of the Earth's core magnetic field and the modulation of the density of the inner radiation belts during the solar cycle, as a function of the L value that characterises the drift shell, where charged particles are trapped. To study the evolution of the particle flux anomaly, we rely on a Principal Component Analysis (PCA) of either POES particle flux or CALIOP dark noise. Analysed data are distributed on a geographical grid at satellite altitude, based on a L-shell reference frame constructed from the moving eccentric dipole. Changes in the main magnetic field are responsible for the observed westward drift. Three PCA modes account for the time evolution related to solar effects. Both the first and second modes have a good correlation with the thermospheric density, which varies in response to the solar cycle. The first mode represents the total intensity variation of the particle flux in the SAA, and the second the movement of the anomaly between different L-shells. The proposed analysis allows us to well recover the westward drift rate, as well as the latitudinal and longitudinal solar cycle oscillations, although the analysed data do not cover a complete (Hale) magnetic solar cycle (around 22 yr). Moreover, the developments

  16. Life-cycle analysis of product integrated polymer solar cells

    DEFF Research Database (Denmark)

    Espinosa Martinez, Nieves; García-Valverde, Rafael; Krebs, Frederik C

    2011-01-01

    economics through design to functionality. An LCA study was performed to quantify the energy use and greenhouse gas (GHG) emissions from electricity use in the manufacture of a light-weight lamp based on a plastic foil, a lithium-polymer battery, a polymer solar cell, printed circuitry, blocking diode......A life cycle analysis (LCA) on a product integrated polymer solar module is carried out in this study. These assessments are well-known to be useful in developmental stages of a product in order to identify the bottlenecks for the up-scaling in its production phase for several aspects spanning from...... on the complete product integrated polymer solar cell. We have compared this portable lighting system with other lighting solutions, namely: a kerosene lamp in a remote rural area in Africa (Ethiopia), as a replacement of a silicon PV based lamp, in place of a torch with non-rechargeable lead-acid battery...

  17. A solar cycle of spacecraft anomalies due to internal charging

    Directory of Open Access Journals (Sweden)

    G. L. Wrenn

    Full Text Available It is important to appreciate how the morphology of internal charging of spacecraft systems, due to penetrating electrons, differs from that of the more common surface charging, due to electrons with lower energy. A specific and recurrent anomaly on a geostationary communication satellite has been tracked for ten years so that solar cycle and seasonal dependencies can be clearly established. Concurrent measurements of sunspot number, solar wind speed and 2-day >2 MeV electron fluence are presented to highlight pertinent space weather relationships, and the importance of understanding the complex particle interaction processes involved.

    Key words. Magnetospheric physics (energetic particles; trapped; solar wind – magnetosphere interactions – space plasma physics (spacecraft sheaths, wakes, charging

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

    Science.gov (United States)

    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.

  19. Current trends in ground based solar magnetometry

    Science.gov (United States)

    Gosain, Sanjay

    2016-07-01

    Continuous observations of the sun, over more than a century, have led to several important discoveries in solar astronomy. These include the discovery of the solar magnetism and its cyclic modulation, active region formation and decay and their role in energetic phenomena such as fares and coronal mass ejections (CMEs), fine structure and dynamics of the sunspots and small-scale organization of the magnetic flux in the form of flux tubes and so forth. In this article we give a brief overview of advancements in solar observational techniques in recent decades and the results obtained from the such observations. These include techniques to achieve high angular resolution, high spectral and polarimetric sensitivity and innovative new detectors. A wide range of spatial, temporal and spectral domains exploited by solar astronomers to understand the solar phenomena are discussed. Many new upcoming telescopes and instruments that are designed to address different aspects of solar physics problems are briefly described. Finally, we discuss the advantages of observing from the ground and how they can complement space-based observations.

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

    Science.gov (United States)

    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.

  1. The Mild Space Weather in Solar Cycle 24

    CERN Document Server

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

    2015-01-01

    The space weather is extremely mild during solar cycle 24: the number of major geomagnetic storms and high-energy solar energetic particle events are at the lowest since the dawn of the space age. Solar wind measurements at 1 AU using Wind and ACE instruments have shown that there is a significant drop in the density, magnetic field, total pressure, and Alfven speed in the inner heliosphere as a result of the low solar activity. The drop in large space weather events is disproportionately high because the number of energetic coronal mass ejections that cause these events has not decreased significantly. For example, the rate of halo CMEs, which is a good indicator of energetic CMEs, is similar to that in cycle 23, even though the sunspot number has declined by about 40%. The mild space weather seems to be a consequence of the anomalous expansion of CMEs due to the low ambient pressure in the heliosphere. The anomalous expansion results in the dilution of the magnetic contents of CMEs, so the geomagnetic storm...

  2. Solar cycle 22 control on daily geomagnetic variation at Terra Nova Bay (Antarctica

    Directory of Open Access Journals (Sweden)

    P. Palangio

    1998-06-01

    Full Text Available Nine summer geomagnetic observatory data (1986-1995 from Terra Nova Bay Base, Antarctica (Lat.74.690S, Long. 164.120E, 80.040S magnetic latitude are used to investigate the behaviour of the daily variation of the geomagnetic field at polar latitude. The instrumentation includes a proton precession magnetometer for total intensity |F| digital recordings; DI magnetometers for absolute measuring of the angular elements D and I and a three axis flux-gate system for acquiring H,D Z time variation data. We find that the magnetic time variation amplitude follows the solar cycle evolution and that the ratio between minimum solar median and maximum solar median is between 2-3 for intensive elements (H and Z and 1.7 for declination(D. The solar cycle effect on geomagnetic daily variation elements amplitude in Antarctica, in comparison with previous studies, is then probably larger than expected. As a consequence, the electric current system that causes the daily magnetic field variation reveals a quite large solar cycle effect at Terra Nova Bay.

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

    Science.gov (United States)

    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.

  4. The Solar Rotational Activity Variations during the 23-th Solar Cycle

    Science.gov (United States)

    Werner, R.; Hempelmann, A.; Valev, D.; Kostadinov, I.; Atanassov, At.; Giovanelli, G.; Petritoli, A.; Bortoli, D.; Ravegnani, F.

    2006-03-01

    The study of the solar activity variability has been of great interest since its discovery. On the one hand it is important for the understanding of the Sun as an active star and on the other hand for the investigations of the solar-terrestrial connections. The solar magnetic field reverses approximately every 22 years, and manifests the 11-year solar cycle, in which the Sun changes its activity from its maximum value to the minimum one. The activity variations, developed by the sun surface rotation in connection with the nonsymmetrical distribution of active regions over the solar disc appear in a shorter time scale. As it is well known, these variations have periods of about 27 days. The solar surface rotates with different velocity, depending on the latitude. The differential solar rotation period, observed from the Earth, varies from 26.75 days at the solar equator up to approximately 29 days at higher latitudes. However the observed periodicity is generally in a wider range: from 20 up to 36 days. This wider spread is a result of the combination of both active-region evolution and solar rotation. A simple empirical solar activity model is proposed, which describes the obtained behavior by harmonic oscillations with simultaneous amplitude and phase modulation. The solar rotational periodicity is analyzed using wavelet. It is demonstrated, that the model describes well the separate episodes of the active region evolution. Both kinds of modulations are the consequence of activity region growth or decay and hence, they are a result of a variable pattern of spots and active regions on the solar surface.

  5. Review of supercritical CO2 power cycle technology and current status of research and development

    Directory of Open Access Journals (Sweden)

    Yoonhan Ahn

    2015-10-01

    Full Text Available The supercritical CO2 (S-CO2 Brayton cycle has recently been gaining a lot of attention for application to next generation nuclear reactors. The advantages of the S-CO2 cycle are high efficiency in the mild turbine inlet temperature region and a small physical footprint with a simple layout, compact turbomachinery, and heat exchangers. Several heat sources including nuclear, fossil fuel, waste heat, and renewable heat sources such as solar thermal or fuel cells are potential application areas of the S-CO2 cycle. In this paper, the current development progress of the S-CO2 cycle is introduced. Moreover, a quick comparison of various S-CO2 layouts is presented in terms of cycle performance.

  6. Characteristics of the 23 Cycle of Solar Activity

    Science.gov (United States)

    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

  7. Recurrence quantification analysis of two solar cycle indices

    Science.gov (United States)

    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.

  8. Radiation exposure of German aircraft crews under the impact of solar cycle 23 and airline business factors.

    Science.gov (United States)

    Frasch, Gerhard; Kammerer, Lothar; Karofsky, Ralf; Schlosser, Andrea; Stegemann, Ralf

    2014-12-01

    The exposure of German aircraft crews to cosmic radiation varies both with solar activity and operational factors of airline business. Data come from the German central dose registry and cover monthly exposures of up to 37,000 German aircraft crewmembers that were under official monitoring. During the years 2004 to 2009 of solar cycle 23 (i.e., in the decreasing phase of solar activity), the annual doses of German aircraft crews increased by an average of 20%. Decreasing solar activity allows more galactic radiation to reach the atmosphere, increasing high-altitude doses. The rise results mainly from the less effective protection from the solar wind but also from airline business factors. Both cockpit and cabin personnel differ in age-dependent professional and social status. This status determines substantially the annual effective dose: younger cabin personnel and the elder pilots generally receive higher annual doses than their counterparts. They also receive larger increases in their annual dose when the solar activity decreases. The doses under this combined influence of solar activity and airline business factors result in a maximum of exposure for German aircrews for this solar cycle. With the increasing solar activity of the current solar cycle 24, the doses are expected to decrease again.

  9. Towards better constrained models of the solar magnetic cycle

    Science.gov (United States)

    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

  10. Intensity modulated short circuit current spectroscopy for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kavasoglu, Nese; Sertap Kavasoglu, A.; Birgi, Ozcan; Oktik, Sener [Mugla University, Faculty of Arts and Sciences, Physics Department, TR-48000 Mugla (Turkey); Mugla University Clean Energy Research and Development Centre, TR-48000 Mugla (Turkey)

    2011-02-15

    Understanding charge separation and transport is momentously important for the rectification of solar cell performance. To probe photo-generated carrier dynamics, we implemented intensity modulated short circuit current spectroscopy (IMSCCS) on porous Si and Cu(In{sub x},Ga{sub 1-x})Se{sub 2} solar cells. In this experiment, the solar cells were lightened with sinusoidally modulated monochromatic light. The photocurrent response of the solar cell as a function of modulation frequency is measured as the optoelectronic transfer function of the system. The optoelectronic transfer function introduces the connection between the modulated light intensity and measured AC current of the solar cell. In this study, interaction of free carriers with the density of states of the porous Si and Cu(In{sub x}, Ga{sub 1-x})Se{sub 2} solar cells was studied on the basis of charge transport time by IMSCCS data. (author)

  11. Economic comparison of solar hydrogen generation by means of thermochemical cycles and electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Graf, D.; Monnerie, N.; Roeb, M.; Schmitz, M.; Sattler, C. [German Aerospace Center, Institute of Technical Thermodynamics, Solar Research, Linder Hoehe, 51147 Cologne (Germany)

    2008-09-15

    Hydrogen is acclaimed to be an energy carrier of the future. Currently, it is mainly produced by fossil fuels, which release climate-changing emissions. Thermochemical cycles, represented here by the hybrid-sulfur cycle and a metal oxide based cycle, along with electrolysis of water are the most promising processes for 'clean' hydrogen mass production for the future. For this comparison study, both thermochemical cycles are operated by concentrated solar thermal power for multistage water splitting. The electricity required for the electrolysis is produced by a parabolic trough power plant. For each process investment, operating and hydrogen production costs were calculated on a 50 MW{sub th} scale. The goal is to point out the potential of sustainable hydrogen production using solar energy and thermochemical cycles compared to commercial electrolysis. A sensitivity analysis was carried out for three different cost scenarios. As a result, hydrogen production costs ranging from 3.9-5.6 EUR/kg for the hybrid-sulfur cycle, 3.5-12.8 EUR/kg for the metal oxide based cycle and 2.1-6.8 EUR/kg for electrolysis were obtained. (author)

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

    Science.gov (United States)

    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.

  13. The Total Solar Irradiance, UV Emission and Magnetic Flux during the Last Solar Cycle Minimum

    Directory of Open Access Journals (Sweden)

    E. E. Benevolenskaya

    2013-01-01

    Full Text Available We have analyzed the total solar irradiance (TSI and the spectral solar irradiance as ultraviolet emission (UV in the wavelength range 115–180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (the solar radiation and climate experiment during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the midlatitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long-lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots, a coherent structure has been found, in which the phase between the integrated midlatitude magnetic flux is ahead of the total solar irradiance on the timescales of the surface rotation.

  14. Understanding Activity Cycles of Solar Type Stars with Kepler

    Science.gov (United States)

    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.

  15. On Global Magnetic ``Monopoly'' Near Solar Cycle Maximums

    Science.gov (United States)

    Kryvodubskyj, V.

    During last maximums of the solar activity the both poles of the polar magnetic field had the same polarity. Since in the turbulent α Ω -dynamo model the excitation thresholds of the periodic dipole and quadrupole modes of the poloidal madnetic field (PMF) are rather close [Parker E. N.: 1971, Ap.J. V. 164, p. 491] then it is possible that the quadrupole mode may be excited due to variations of physical parameters in a some regions of the solar convection zone (SCZ). The pattern of the excited modes (dipole, quadrupole, octupole, etc.) is determined by the values of wave number of the Parker's dynamo-wave. We calculated these values for the SCZ model by Stix (1989) [Stix M.: 1989, The Sun. Berlin, p. 200] in the vicinity of solar tachocline (a region of strong shear of angular velocity at the base of the SCZ) with using our estimation of the helical turbulence parameter [Krivodubskij V. N.: 1998, Astron. Reports V. 42, No 1, p. 122] and values of the radial gradient of the angular velocity obtained from the newer helioseismic measurements (during rising phase of 23th solar cycle: 1995-1999) [Howe R.,Christensen-Dalsgaard J., Hill F. et al.: 2000, Science. V. 287, p. 2456]. It is found out that at low latitudes dynamo mechanism produces rather the dipole (wave number ≈ -7), the main antisymmetric, relatively to equatorial plane, mode of the PMF; while at the latitudes higher than 50o the conditions are more favourable for exciting of the quadrupole (wave number ≈ +8), the lowest symmetric mode. Arised north-south magnetic structure asymmetry gives an opportunity to explain the space magnetic anomaly of the PMF (``monopoly'') observed near solar cycle maximums.

  16. Current European developments in solar paddle drives

    Science.gov (United States)

    Bentall, R. H.

    1973-01-01

    The European Space Research and Technology Centre (ESTEC) is sponsoring the development of a number of critical spacecraft hardware items. The hardware under development includes two competing solar paddle drives which are being produced to similar specifications. Three mechanisms of each type are being produced and will undergo thermal vacuum testing. All mechanisms have lead lubricated bearings.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

    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 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*(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. (author)

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

    Science.gov (United States)

    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.

  1. Predicting the start and maximum amplitude of solar cycle 24 using similar phases and a cycle grouping

    Institute of Scientific and Technical Information of China (English)

    Jia-Long Wang; Wei-Guo Zong; Gui-Ming Le; Hai-Juan Zhao; Yun-Qiu Tang; Yang Zhang

    2009-01-01

    We find that the solar cycles 9, 11, and 20 are similar to cycle 23 in their respective descending phases. Using this similarity and the observed data of smoothed monthly mean sunspot numbers (SMSNs) available for the descending phase of cycle 23, we make a date calibration for the average time sequence made of the three descending phases of the three cycles, and predict the start of March or April 2008 for cycle 24. For the three cycles, we also find a linear correlation of the length of the descending phase of a cycle with the difference between the maximum epoch of this cycle and that of its next cycle.Using this relationship along with the known relationship between the rise-time and the maximum amplitude of a slowly rising solar cycle, we predict the maximum SMSN of cycle 24 of 100.2±7.5 to appear during the period from May to October 2012.

  2. Evolution of sunspot properties during solar cycle 23

    CERN Document Server

    Watson, Fraser T; Marshall, Stephen; 10.1051/0004-6361/201116655

    2011-01-01

    The long term study of the Sun is necessary if we are to determine the evolution of sunspot properties and thereby inform modeling of the solar dynamo, particularly on scales of a solar cycle. We aim to determine a number of sunspot properties over cycle 23 using the uniform database provided by the SOHO Michelson Doppler Imager data. We focus in particular on their distribution on the solar disk, maximum magnetic field and umbral/penumbral areas. We investigate whether the secular decrease in sunspot maximum magnetic field reported in Kitt Peak data is present also in MDI data. We have used the Sunspot Tracking And Recognition Algorithm (STARA) to detect all sunspots present in the SOHO Michelson Doppler Imager continuum data giving us 30 084 separate detections. We record information on the sunspot locations, area and magnetic field properties and corresponding information for the umbral areas detected within the sunspots, and track them through their evolution. We find the total visible umbral area is 20-4...

  3. Climate Sensitivity and Solar Cycle Response in Climate Models

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. China's Current Real Estate Cycle and Potential Financial Risks

    Institute of Scientific and Technical Information of China (English)

    Xiaojing Zhang; Tao Sun

    2006-01-01

    The real estate cycle and financial stability are closely correlated. In light of global real estate bubbles, China's real estate cycle has attracted wide attention since 1998. The present paper analyzes three driving factors in the context of the current real estate cycle; namely,economic growth, macroeconomic environment and institutional establishment. Supported by econometric analysis using quarterly data from 1992-2004, the present paper indicates that real estate will develop steadily and that housing prices will consistently rise in the relative long run. Based on quantitative analysis, it is concluded that the implications of the current real estate cycle for financial stability include risks of real estate credit exposure,government guarantees and maturity mismatch. Some corresponding policy implications are discussed, such as advancing banking reform, encouraging the rational behavior of local governments and strengthening the regulation of foreign capital flows in and out of China's real estate industry.

  6. High-energy solar particle events in cycle 24

    CERN Document Server

    Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Akiyama, Sachiko; Thakur, Neeharika

    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...

  7. Occurrence of Sporadic -E layer during the Ending Phase of Solar Cycle 23rd and Rising Phase of Solar Cycle 24th over the Anomaly Crest Region Bhopal

    Science.gov (United States)

    Bhawre, Purushottam; Gwal, Ashok Kumar; Tripathi, Sharad Chandra; Mansoori, Azad Ahmad; Aslam A., M.; Khan, Parvaiz A.; Purohit, Pramod K.; Waheed, Malik Abdul; Khatarkar, Prakash

    Ionospheric anomaly crest regions are most challenging for scientific community to understand its mechanism and investigation, for this purpose we are investigating some inospheric result for this region. The study is based on the ionogram data recorded by IPS-71 Digital Ionosonde installed over anomaly crust region Bhopal (Geo.Lat.23.2° N, Geo. Long77.4° E, Dip latitude18.4°) over a four year period from January 2007 to December 2010, covering the ending phase of 23rd Solar Cycle and starting phase of 24th solar cycle. This particular period is felt to be very suitable for examining the sunspot number and it encompasses periods of low solar activities. Quarterly ionograms are analyzed for 24 hours during these study years and have been carefully examined to note down the presence of sporadic- E. We also note down the space weather activities along with the study. The studies are divided in mainly four parts with space and geomagnetic activities during these periods. The occurrence probability of this layer is highest in summer solstice, moderate during equinox and low during winter solstice. Remarkable occurrence peaks appear from June to July in summer and from December to January in winter. The layer occurrence showed a double peak variation with distinct layer groups, in the morning (0200 LT) and the other during evening (1800 LT).The morning layer descent was associated with layer density increase indicating the strengthening of the layer while it decreased during the evening layer descent. The result indicates the presence of semi-diurnal tide over the location while the higher descent velocities could be due to the modulation of the ionization by gravity waves along with the tides. The irregularities associated with the gradient-drift instability disappear during the counter electrojet and the current flow is reversed in westward. Keyword: ionosphere, solar cycle, sporadic - E

  8. Temporal Offsets between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators during Solar Cycle 23 and the Ascending Phase of Cycle 24

    CERN Document Server

    Özgüç, A; Georgieva, K; Kirov, B

    2016-01-01

    On the basis of morphological analysis of yearly values of the maximum CME (coronal mass ejection) 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 Dst indices, we point out the particularities of solar and geomagnetic activity during the last cycle 23, the long minimum which followed it and the ascending branch of cycle 24. We also analyze 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 the descending phases of solar cycle 23. It is noticed that the hysteresis phenomenon represents a clue in the search for physical processes responsi...

  9. Solar Cycle Variations of Fe-rich SEP Events

    Science.gov (United States)

    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.

  10. An Investigation of Geomagnetic Storms and Associated Cosmic Ray Intensity During Recent Solar Cycle

    Science.gov (United States)

    Kaushik, Sonia

    2016-07-01

    Shocks driven by energetic coronal mass ejections (CME's) and other interplanetary (IP) transients are mainly responsible for initiating large and intense geomagnetic storms. Observational results indicate that galactic cosmic rays (CR) coming from deep surface interact with these abnormal solar and IP conditions and suffer modulation effects. The current solar cycle has provided a long list of these highly energetic events influencing the Earth's geomagnetic field up to a great extent. We have selected such intense geo-effective CME's occurred during recent solar cycle and studied their possible influence on cosmic ray intensity as well as on Earth' s geomagnetic field using the hourly values of IMF data obtained from the NSSD Center. Solar wind data obtained from various satellites are used in the studies which are available during the selected events period. The super neutron monitor data obtained from Kiel, Oulu and Huancayo stations, well distributed over different latitudes has been used in the present study. It is found that AP and AE indices show rise before the forward turnings of IMF and both the Dst index and cosmic ray intensity show a classic decrease. The analysis further indicates the significant role of the magnitudes of Bz component of IMF substantiating the earlier results. It is further inferred that the magnitude of these responses depends on BZ component of IMF being well correlated with solar maximum and minimum periods. Transient decrease in cosmic ray intensity with slow recovery is observed during the storm phase duration.

  11. Analysis of Plasma and Field Conditions during Some Intensely Geo-effective Transient Solar/Interplanetary Disturbances of Solar Cycle 23

    Indian Academy of Sciences (India)

    Yatendra Pal Singh; Munendra Singh; Badruddin

    2006-06-01

    The problem of solar wind–magnetosphere coupling is investigated for intense geomagnetic storms (Dst ≤ -100 nT) that occurred during solar cycle 23. For this purpose interplanetary plasma and field data during some intensely geo-effective transient solar/interplanetary disturbances have been analysed. A geomagnetic index that represents the intensity of planetary magnetic activity at subauroral latitude and the other that measures the ring current magnetic field, together with solar plasma and field parameters (V, B, Bz, B, N, and T) and their various derivatives (BV, -BVz, BV2, -BzV2, B2V, Bz2V, NV2) have been analysed in an attempt to study mechanism and the cause of geo-effectiveness of interplanetary manifestations of transient solar events. Several functions of solar wind plasma and field parameters are tested for their ability to predict the magnitude of geomagnetic storm.

  12. A study of north-south asymmetry of interplanetary magnetic field plasma and some solar indices throughout four solar cycles

    Science.gov (United States)

    El-Borie, M. A.; Abdel-halim, A. A.; El-Monier, S. Y.; Bishara, A. A.

    2017-06-01

    We provide a long epoch study of a set of solar and plasma parameters (sunspot number Rz, total solar irradiance TSI, solar radio flux SF, solar wind speed V, ion density n, dynamic pressure nV 2, and ion temperature T) covering a temporal range of several decades corresponding to almost four solar cycles. Such data have been organized accordingly with the interplanetary magnetic field (IMF) polarity, i.e. away (A) if the azimuthal component of the IMF points away from the Sun and T if it points towards, to examine the N-S asymmetries between the northern and southern hemispheres. Our results displayed the sign of the N-S asymmetry in solar activity depends on the solar magnetic polarity state (qA>0 or qAIMF points away from the Sun. Moreover, during solar cycles 21st and 24th the solar plasma is more dense, hotter, and faster south of the HCS.

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

    Science.gov (United States)

    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.

  14. Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24

    CERN Document Server

    Zhao, L -L; Zhang, M; Heber, B

    2013-01-01

    During the recent solar minimum between cycles 23 and 24 (solar minimum $P_{23/24}$) the intensity of Galactic Cosmic Rays (GCRs) measured at the Earth was the highest ever recorded since space age. It is known that both the Interplanetary Magnetic Field (IMF) strength and the Solar Wind (SW) speed were very low, but the tilt of Heliospheric Current Sheet (HCS) was not at the lowest level. This indicates that the modulation of cosmic rays is not dominated by the mechanism of particle drift through the current sheet during this $A<0$ cycle as we normally think. In this paper, we use a model of GCR transport in three-dimensional heliosphere based on a simulation of Markov stochastic process to study the possible causes for the unusually high GCR intensity. We first investigate how cosmic ray modulation is affected by the solar wind and heliospheric magnetic field parameters such as SW speed, distance of heliospheric boundary, magnitude of IMF at the Earth, values of parallel and perpendicular diffusion coeff...

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

    Science.gov (United States)

    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.

  16. Solar wind drivers of geomagnetic storms during more than four solar cycles

    Directory of Open Access Journals (Sweden)

    Richardson Ian G.

    2012-05-01

    Full Text Available Using a classification of the near-Earth solar wind into three basic flow types: (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 (CMEs at the Sun, including interplanetary CMEs and the associated upstream shocks and post-shock regions, we determine the drivers of geomagnetic storms of various size ranges based on the Kp index and the NOAA “G” criteria since 1964, close to the beginning of the space era, to 2011, encompassing more than four solar cycles (20–23. We also briefly discuss the occurrence of storms since the beginning of the Kp index in 1932, in the minimum before cycle 17. We note that the extended low level of storm activity during the minimum following cycle 23 is without precedent in this 80-year interval. Furthermore, the “typical” numbers of storm days/cycle quoted in the standard NOAA G storm table appear to be significantly higher than those obtained from our analysis, except for the strongest (G5 storms, suggesting that they should be revised downward.

  17. Magnetization collapse in polycrystalline YBCO under transport current cycles

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, J L [Departamento de Ciencias de la IngenierIa, Universidad de Talca (Chile); Luzuriaga, J [Centro Atomico Bariloche, CNEA, Instituto Balseiro, UNC (Argentina); BadIa-Majos, A [Departamento de Fisica de la Materia Condensada-ICMA, Universidad de Zaragoza (Spain); Nieva, G [Centro Atomico Bariloche, CNEA, Instituto Balseiro, UNC (Argentina); RuIz-Tagle, I [Instituto de QuImica de Recursos Naturales, Universidad de Talca (Chile)

    2006-04-15

    We report measurements of the hysteretic magnetization of YBCO under superimposed transport current cycles, together with numerical simulations of magnetization and current density profiles in the corresponding parallel configuration. Field cooled (FC) and zero-field-cooled (ZFC) experiments were carried out on polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-x} cylinders, with both the applied magnetic field and transport current in the axial direction, and the current cycled several times, around and above the dissipative threshold. As in previously reported multicomponent field configuration experiments, the magnetization is seen to collapse to a more stable state both in FC and ZFC, because of the interplay between the shielding and transport currents. The results of our numerical simulations are in good qualitative agreement with the measurements, and the competition between shielding and transport due to vortex-pinning interactions and equilibrium magnetization effects are shown to play an important role in the range of our experiments.

  18. Evidence of solar induced cycles of high seismic activity

    Science.gov (United States)

    Duma, G.

    2010-12-01

    In the past century, several observational results and corresponding publications indicate a systematic seismic performance with respect to the time of day and seasons as well. Such effects could be caused only by solar or lunar influence. In addition, a possible relation with the solar cycles was discussed in some papers, too. Intensive studies on these topics have also been performed at the Central Institute for Meteorology and Geodynamics (ZAMG), Vienna, Austria. They strongly confirm the above mentioned effects. In order to verify a solar influence on earthquake activity correlations were performed between the three-hour magnetic index Kp and the energy release of earthquakes in the long term. Kp characterizes the magnetic field disturbances which are mainly caused by the solar particle radiation, the solar wind. Kp is determined on a routine basis from magnetic records of 13 observatories worldwide and is continuously published by ISGI, France. Three regions of continental size were investigated, using the USGS (PDE) earthquake catalogue data, from 1974 on: N-America, S-America and Eurasia. The statistic analyses reveal that from 1974 to 2009 the index Kp varies in cycles with periods between 9 and 12 years, somewhat different to the sunspot number cycles (no. 21, 22, 23) of 11 years. As to the seismic energy release, the sqrt (energy E) of an event is taken as measure, which relates to the ‘strain release’ due to the earthquake (Benioff). For Kp the monthly averages were computed, for the strain release the monthly sums of sqrt(E), hereinafter referred to as STR. From the statistic estimates of the relation Kp-STR for all the three regions N-America, S-America and Eurasia it becomes evident, that the correlation is highly significant: earthquake activity, quantified by the monthly STR, follows the Kp cycles with high coincidence. A quantitative analysis reveals that on an annual basis, the sum of released energy by earthquakes changes by a factor up to

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

    Science.gov (United States)

    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).

  20. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Science.gov (United States)

    Yizengaw, Endawoke; Carter, Brett A.

    2017-04-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (Kp>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  1. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Energy Technology Data Exchange (ETDEWEB)

    Yizengaw, Endawoke [Boston College, Chestnut Hill, MA (United States). Inst. for Scientific Research; Carter, Brett A. [RMIT Univ., Melbourne, VIC (Australia). SPACE Research Centre

    2017-07-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K{sub p}>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  2. Corona during the total solar eclipse on March 20, 2015, and 24 cycle development

    Science.gov (United States)

    Yazev, Sergey; Mordvinov, Aleksandr; Dvorkina-Samarskaya, Antonina

    2016-06-01

    We analyzed the structure of coronal features, using data on the March 20, 2015 total solar eclipse. The Ludendorff index characterizing the flattening of the corona is 0.09. The solar corona structure in the Northern and Southern hemispheres corresponds to the maximum and post-maximum phases of solar activity, respectively. The asynchronous development of magnetic activity in the Sun's Northern and Southern hemispheres caused a substantial asymmetry of coronal features observed at the reversal of polar magnetic fields in the current cycle. The polar ray structures in the Southern Hemisphere are associated with the polar coronal hole, while in the Northern Hemisphere a polar hole has not been formed yet. We examine the relation between large-scale magnetic fields and location of high coronal structures.

  3. Sources of The Slow Solar wind During the Solar Cycle 23/24 Minimum

    CERN Document Server

    Kilpua, E K J; Karna, N; Wiegelmann, T; Farrugia, C; Yu, W; Andreeova, K

    2016-01-01

    We investigate the characteristics and the sources of the slow (< 450 km/s) solar wind during the four years (2006-2009) of low solar activity between Solar Cycles 23 and 24. We use a comprehensive set of in-situ observations in the near-Earth solar wind (Wind and ACE) and remove 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 examine both Carrington Rotation averages of selected solar plasma, charge state and compositional parameters and distributions of these parameters related to 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 ratio) show clear variations over our study period and with solar wind source type, some (Fe/...

  4. Solar-Like Cycle in Asymptotic Giant Branch Stars

    CERN Document Server

    Soker, N

    2000-01-01

    I propose that the mechanism behind the formation of concentric semi-periodic shells found in several planetary nebulae (PNs) and proto-PNs, and around one asymptotic giant branch (AGB) star, is a solar-like magnetic activity cycle in the progenitor AGB stars. The time intervals between consecutive ejection events is about 200-1,000 years, which is assumed to be the cycle period (the full magnetic cycle can be twice as long, as is the 22-year period in the sun). The magnetic field has no dynamical effects; it regulates the mass loss rate by the formation of magnetic cool spots. The enhanced magnetic activity at the cycle maximum results in more magnetic cool spots, which facilitate the formation of dust, hence increasing the mass loss rate. The strong magnetic activity implies that the AGB star is spun up by a companion, via a tidal or common envelope interaction. The strong interaction with a stellar companion explains the observations that the concentric semi-periodic shells are found mainly in bipolar PNs.

  5. High-Energy Solar Particle Events in Cycle 24

    Science.gov (United States)

    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).

  6. Estimate of the upper limit of amplitude of Solar Cycle No. 23

    Energy Technology Data Exchange (ETDEWEB)

    Silbergleit, V. M; Larocca, P. A [Departamento de Fisica, UBA (Argentina)

    2001-07-01

    AA* indices of values greater than 60 10{sup -9} Tesla are considered in order to characterize geomagnetic storms since the available series of these indices comprise the years from 1868 to 1998 (The longest existing interval of geomagnetic activity). By applying the precursor technique we have performed an analysis of the storm periods and the solar activity, obtaining a good correlation between the number of storms ({alpha})(characterized by the AA* indices) and the amplitudes of each solar cycle ({zeta}) and those of the next ({mu}). Using the multiple regression method applied to {alpha}=A+B{zeta} +C{mu}, the constants are calculated and the values found are: A=-33 {+-}18, B= 0.74{+-}0.13 y C= 0.56{+-}0.13. The present statistical method indicates that the current solar cycle (number 23) would have an upper limit of 202{+-}57 monthy mean sunspots. This value indicates that the solar activity would be high causing important effects on the Earth's environment. [Spanish] Se consideran los valores de los indices AA* de valor mayor que 60 10{sup -9} Tesla para caracterizar tormentas geomagneticas ya que las series disponibles de estos indices van desde 1868 hasta 1998 (el mas largo intervalo de la actividad geomagnetica existente). Aplicando la tecnica del precursor hemos realizado un analisis de los periodos de tormentas y la actividad solar obteniendo una buena correlacion entre el numero de tormentas ({alpha}) (caracterizado por los indices AA*) y las amplitudes de los ciclos solares corriente ({zeta}) y el proximo ({mu}). Usando el metodo de regresion multiple aplicado a {alpha}=A+B{zeta} +C{mu}, las consonantes resultaron: A=-33 {+-}18, B= 0.74{+-}0.13 y C= 0.56{+-}0.13. El metodo estadistico presentado indica que el ciclo actual (numero 23) tendria un pico de 202{+-} 57 manchas mensuales promedio. Este valor indica que la actividad solar seria alta produciendo importantes efectos en el medio ambiente terrestre.

  7. Properties of Magnetic Tongues over a Solar Cycle

    CERN Document Server

    Poisson, M; Fuentes, M López; Mandrini, C H

    2016-01-01

    The photospheric spatial distribution of the main magnetic polarities of bipolar active regions (ARs) presents 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. (2015, Solar Phys. 290, 727) 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 em...

  8. Differential rotation of solar background magnetic fields during the 20th solar cycle

    Science.gov (United States)

    Hejna, L.

    1983-11-01

    The study demonstrates the possibility of using the autocorrelation analysis for studies of the differential rotation of the solar background magnetic fields. For that purpose the time series obtained from the synoptic Hα charts published by McIntosh were subjected to an analysis. On their basis the distribution of the synodic angular velocity in time - during the cycle - and in the heliographic latitude - for |φ| smaller than 60° - was determined. After that the parameters A and B from the relation for differential rotation ω = A+B sin2φ could be determined, both for the entire cycle and for individual Carrington rotations.

  9. Solar neutrino: Flux, cosmic rays and the 11 year solar cycle

    Science.gov (United States)

    Raychaudhuri, P.

    1985-01-01

    It is shown that the results of maximum likelihood treatment of Monte Carlo simulation with constant production rate of 7.6 SNU and 1.Epsilon SNU are consistent with the constant production rate when the tests of hypotheses (e.g., t-test, sigma squared-test, Wilcoxon-Mann-Whitney test, run test, etc.) are applied to the two groups of data formed from sunspot minimum range and sunspot maximum range, whereas the real data pulsates with the solar activity cycle. It is shown that SN flux-change is in opposition phase to the solar activity cycle and lags behind the latter by about one year. A correlation between SN flux and the cosmic rays is suggested.

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

    Science.gov (United States)

    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.

  11. Cosmic and solar radiation exposure for aircrew over a solar cycle

    Energy Technology Data Exchange (ETDEWEB)

    Desormeaux, M. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)

    2003-07-01

    Over the past decade, extensive research has been performed at the Royal Military College of Canada to determine the radiation exposure of aircrew, and to assess the recommendation of the International Commission for Radiological Protection (ICRP) that aircrew should be considered as occupationally exposed workers. This research confirmed the ICRP findings and demonstrated that galactic cosmic radiation could be effectively predicted, which has led to the development of a semi-empirical computer model capable of predicting route doses over an entire solar cycle. Following ongoing validation, model improvement has been performed for short-haul and low-altitude flights, as well as flights done during solar minimum conditions. Furthermore, a model has also been proposed to account for the additional radiation exposure from solar particle events (SPEs). (author)

  12. Cosmic and solar radiation exposure for aircrew over a solar cycle

    Energy Technology Data Exchange (ETDEWEB)

    Desormeaux, M. [Royal Military College of Canada, Kingston, Ontario (Canada)

    2003-08-01

    Over the past decade, extensive research has been performed at the Royal Military College of Canada to determine the radiation exposure of aircrew, and to assess the recommendation of the International Commission for Radiological Protection (ICRP) that aircrew should be considered as occupationally exposed workers. This research confirmed the ICRP findings and demonstrated that galactic cosmic radiation could be effectively predicted, which has led to the development of a semi-empirical computer model capable of predicting route doses over an entire solar cycle. Following ongoing validation, model improvement has been performed for short-haul and low-altitude flights, as well as flights done during solar minimum conditions. Furthermore, a model has also been proposed to account for the additional radiation exposure from solar particle events (SPEs). (author)

  13. Solar fuel processing efficiency for ceria redox cycling using alternative oxygen partial pressure reduction methods

    OpenAIRE

    Lin, Meng; Haussener, Sophia

    2015-01-01

    Solar-driven non-stoichiometric thermochemical redox cycling of ceria for the conversion of solar energy into fuels shows promise in achieving high solar-to-fuel efficiency. This efficiency is significantly affected by the operating conditions, e.g. redox temperatures, reduction and oxidation pressures, solar irradiation concentration, or heat recovery effectiveness. We present a thermodynamic analysis of five redox cycle designs to investigate the effects of working conditions on the fuel pr...

  14. North-south asymmetric solar cycle evolution: Signatures in the photosphere and consequences in the corona

    Energy Technology Data Exchange (ETDEWEB)

    Virtanen, I. I.; Mursula, K., E-mail: ilpo.virtanen@oulu.fi [University of Oulu, P. O. Box 3000, FI-90014 Oulu (Finland)

    2014-02-01

    The heliospheric current sheet is the continuum of the coronal magnetic equator that divides the heliospheric magnetic field into two sectors (polarities). Several recent studies have shown that the heliospheric current sheet is southward shifted during approximately 3 years in the solar declining phase (the so-called bashful ballerina phenomenon). In this article we study the hemispherical asymmetry in the photospheric and coronal magnetic fields using Wilcox Solar Observatory measurements of the photospheric magnetic field since 1976 as well as the potential field source surface model. Multipole analysis of the photospheric magnetic field shows that during the late declining phase of solar cycles since the 1970s, the 'bashful ballerina phenomenon' is a consequence of the g{sub 2}{sup 0} quadrupole term, signed oppositely to the dipole moment. Surges of new flux transport magnetic field from low latitudes to the poles, thus leading to a systematically varying contribution to the g{sub 2}{sup 0}-term from different latitudes. In the case of a north-south asymmetric flux production, this is seen as a quadrupole contribution traveling toward higher latitudes. When the quadrupole term is largest, the main contribution comes from the polar latitudes. At least during the four recent solar cycles, the g{sub 2}{sup 0}-term arises because the magnitude of the southern polar field is larger than the magnitude found in the north in the declining phase of the cycle. In the heliosphere this hemispheric asymmetry of the coronal fields is seen as a southward shift of the heliospheric current sheet by about 2°.

  15. North-South Asymmetric Solar Cycle Evolution: Signatures in the Photosphere and Consequences in the Corona

    Science.gov (United States)

    Virtanen, I. I.; Mursula, K.

    2014-02-01

    The heliospheric current sheet is the continuum of the coronal magnetic equator that divides the heliospheric magnetic field into two sectors (polarities). Several recent studies have shown that the heliospheric current sheet is southward shifted during approximately 3 years in the solar declining phase (the so-called bashful ballerina phenomenon). In this article we study the hemispherical asymmetry in the photospheric and coronal magnetic fields using Wilcox Solar Observatory measurements of the photospheric magnetic field since 1976 as well as the potential field source surface model. Multipole analysis of the photospheric magnetic field shows that during the late declining phase of solar cycles since the 1970s, the "bashful ballerina phenomenon" is a consequence of the g^{0}_{2} quadrupole term, signed oppositely to the dipole moment. Surges of new flux transport magnetic field from low latitudes to the poles, thus leading to a systematically varying contribution to the g^{0}_{2}-term from different latitudes. In the case of a north-south asymmetric flux production, this is seen as a quadrupole contribution traveling toward higher latitudes. When the quadrupole term is largest, the main contribution comes from the polar latitudes. At least during the four recent solar cycles, the g^{0}_{2}-term arises because the magnitude of the southern polar field is larger than the magnitude found in the north in the declining phase of the cycle. In the heliosphere this hemispheric asymmetry of the coronal fields is seen as a southward shift of the heliospheric current sheet by about 2°.

  16. High temperature solar furnace: current applications and future potential

    Energy Technology Data Exchange (ETDEWEB)

    Bjorndalen, N. [Dalhousie Univ., Faculty of Engineering, Halifax, NS (Canada)

    2003-02-15

    The high temperature solar furnace can offer great opportunities for the production of many types of products worldwide, but recent advances in this technology have been limited to metal reduction. The production of semiconductors, which are utilized to a great extent in the electronic industry, is a viable option for this technology that has been overlooked. Especially where sand and sunlight are plentiful (countries that surround the equator), silicon chips produced with a solar furnace can have great economical value. This paper describes current and potential solar furnace technologies. The components of the solar furnace are described, as well as metal reduction processes including zinc and aluminum production. The viability of silicon chip production is also examined. The possibilities for other product development using an extremely (up to 10,000 deg C) high temperature solar furnace are also discussed. Economically, the benefits of solar furnaces are great, with only high initial start-up costs and little operation costs. Metal reduction processes can also be enhanced with high temperature solar furnaces in that plugging problems are eliminated. By replacing conventional furnaces, such as blast and electric arc furnaces, with a high temperature solar furnace, CO{sub 2} emissions and energy consumption can be greatly reduced, which will bring in added dividends to the society. (Author)

  17. High Energetic Solar Proton Flares on the Declining Phase of Solar Cycle 22

    Science.gov (United States)

    Shaltout, M. A. Mosalam

    1995-06-01

    The year 1991 is a part of the declining phase of the solar cycle 22, during which high energetic flares have been produced by active regions NOAA/USAF 6659 in June. The associated solar proton events have affected the Earth environment and their proton fluxes have been measured by GOES space craft. The evaluation of solar activity during the first half of June 1991, have been carried out by applying a method for high energetic solar flares prediction on the flares of June 1991. The method depends on cumulative summation curves according to observed H-alpha flares, X-ray bursts, in the active region 6659 during one rotation when the energetic solar flares of June 1991 have occurred. It has been found that the steep trend of increased activity sets on several tens of hours prior to the occurrence of the energetic flare, which can be used, together with other methods, for forecasts of major flares. All the used data at the present work are received from NOAA, Boulder, Colorado, USA.

  18. Solar disks and solar cycles : spindle whorls and the dawn of solar art in postclassic Mexico

    OpenAIRE

    Brumfiel, Elisabeth

    2007-01-01

    Sun disks are a common motif in spindle whorl decorations at Xaltocan, Mexico. These and other forms of symbolism on domestic artifacts suggest that women participated in the solar cosmologies of Postclassic Central Mexico. These symbols and their cosmologies precede and anticipate the principles of Aztec state religion. Thus, the spindle whorls with solar symbolism suggest that rulers appropriated the symbolism of household units in their efforts to establish the legitimacy of their states. ...

  19. Predicting the Amplitude and Hemispheric Asymmetry of Solar Cycle 25 with Surface Flux Transport

    CERN Document Server

    Hathaway, David H

    2016-01-01

    Evidence strongly indicates that the strength of the Sun's polar fields near the time of a sunspot cycle minimum determines the strength of the following solar activity cycle. We use our Advective Flux Transport (AFT) code, with flows well constrained by observations, to simulate the evolution of the Sun's polar magnetic fields from early 2016 to the end of 2019 --- near the expected time of Cycle 24/25 minimum. We run a series of simulations in which the uncertain conditions (convective motion details, active region tilt, and meridional flow profile) are varied within expected ranges. We find that the average strength of the polar fields near the end of Cycle 24 will be similar to that measured near the end of Cycle 23, indicating that Cycle 25 will be similar in strength to the current cycle. In all cases the polar fields are asymmetric with fields in the south stronger than those in the north. This asymmetry would be more pronounced if not for the predicted weakening of the southern polar fields in late 20...

  20. Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

    Science.gov (United States)

    Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

    2013-01-01

    A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

  1. The heliospheric Hale cycle over the last 300 years and its implications for a “lost” late 18th century solar cycle

    Directory of Open Access Journals (Sweden)

    Owens Mathew J.

    2015-01-01

    Full Text Available A Hale cycle, one complete magnetic cycle of the Sun, spans two complete Schwabe cycles (also referred to as sunspot and, more generally, solar cycles. The approximately 22-year Hale cycle is seen in magnetic polarities of both sunspots and polar fields, as well as in the intensity of galactic cosmic rays reaching Earth, with odd- and even-numbered solar cycles displaying qualitatively different waveforms. Correct numbering of solar cycles also underpins empirical cycle-to-cycle relations which are used as first-order tests of stellar dynamo models. There has been much debate about whether the unusually long solar cycle 4 (SC4, spanning 1784–1799, was actually two shorter solar cycles combined as a result of poor data coverage in the original Wolf sunspot number record. Indeed, the group sunspot number does show a small increase around 1794–1799 and there is evidence of an increase in the mean latitude of sunspots at this time, suggesting the existence of a cycle “4b”. In this study, we use cosmogenic radionuclide data and associated reconstructions of the heliospheric magnetic field (HMF to show that the Hale cycle has persisted over the last 300 years and that data prior to 1800 are more consistent with cycle 4 being a single long cycle (the “no SC4b” scenario. We also investigate the effect of cycle 4b on the HMF using an open solar flux (OSF continuity model, in which the OSF source term is related to sunspot number and the OSF loss term is determined by the heliospheric current sheet tilt, assumed to be a simple function of solar cycle phase. The results are surprising; Without SC4b, the HMF shows two distinct peaks in the 1784–1799 interval, while the addition of SC4b removes the secondary peak, as the OSF loss term acts in opposition to the later rise in sunspot number. The timing and magnitude of the main SC4 HMF peak is also significantly changed by the addition of SC4b. These results are compared with the cosmogenic

  2. Bibliographic Review about Solar Hydrogen Production Through Thermochemical Cycles; Revision Bibliografica sobre la Produccion de Hidrogeno Solar Mediante Ciclos Termoquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.

    2007-12-28

    This report presents a summary of the different thermical processes used to obtain hydrogen through solar energy, paying more attention to the production of hydrogen from water through thermochemical cycles. In this aspect, it is briefly described the most interesting thermochemical cycles, focusing on thermochemical cycles based on oxides. (Author) 25 refs.

  3. Bibliographic Review about Solar Hydrogen Production Through Thermochemical Cycles; Revision Bibliografica sobre la Produccion de Hidrogeno Solar Mediante Ciclos Termoquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.

    2008-08-06

    This report presents a summary of the different thermical processes used to obtain hydrogen through solar energy, paying more attention to the production of hydrogen from water through thermochemical cycles. In this aspect, it is briefly y described the most interesting thermochemical cycles, focusing on thermochemical cycles based on oxides. (Author) 25 refs.

  4. Effect of solar features and interplanetary parameters on geomagnetosphere during solar cycle-23

    Indian Academy of Sciences (India)

    Santosh Kumar; Amita Raizada

    2008-12-01

    The dependence of geomagnetic activity on solar features and interplanetary (IP) parameters is investigated. Sixty-seven intense (−200 nT ≤ Dst < −100 nT) and seventeen superintense (Dst < −200 nT) geomagnetic storms (GMSs) have been studied from January 1996 to April 2006. The number of intense and superintense GMSs show three distinct peaks during the 11-year period of 23rd solar cycle. The largest number of high strength GMSs are observed during maximum phase of solar cycle. Halo and partial halo CMEs are likely to be the major cause for these GMSs of high intensity. No relationship is observed between storm duration and the number of CMEs involved in its occurrence. The intensity of the GMS is also independent of the number of CMEs causing the occurrence of storm. These geoeffective CMEs show western and northern bias. Majority of the geoeffective CMEs are associated with X-ray solar flares (SFs). Solar and IP parameters, e.g., CME, SW, , z (GSE and GSM coordinates) and their products, e.g., SW· and SW·z are observed and correlated to predict the occurrence of intense GMSs. V CME does not seem to be the appropriate parameter with the correlation coefficient, = −0.2 with Dst index, whereas the correlation coefficient, = −0.57, −0.65, 0.75, −0.68 and 0.77 of the parameters SW, , z, SW· and SW·z respectively, with Dst indicating that SW·z and z may be treated as the significant contributors in determining the strength of GMSs.

  5. The Relation between the Amplitude and the Period of Solar Cycles

    Institute of Scientific and Technical Information of China (English)

    Zhan-Le Du; Hua-Ning Wang; Xiang-Tao He

    2006-01-01

    The maximum amplitudes of solar activity cycles are found to be well anticorrelated (r = -0.72) with the newly defined solar cycle lengths three cycles before (at lag -3) in 13-month running mean sunspot numbers during the past 190 years. This result could be used for predicting the maximum sunspot numbers. The amplitudes of Cycles 24and 25 are estimated to be 149.5±27.6 and 144.3±27.6, respectively.

  6. Improved analytical current voltage characteristics of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Koski, M.; Tuominen, E.; Acerbis, M.; Sinkkonen, J.

    1997-12-31

    Application of the Green`s function method to the calculation of the current voltage characteristics of a pn-junction solar cell makes possible to extract more reliable and exact information about the behavior of the cell. With this method not only the minority carrier diffusion currents but also the drift currents in quasi- neutral regions of the solar cell can be taken into consideration. Furthermore, this approach is not limited to an exponentially decaying minority carrier generation function but is valid for any type of optical generation. In addition, the injection boundary condition is exploited with the result that not only the pn-diode current but also the current resulting from the optical generation depends on the voltage of the solar cell. Applying the method also gives the so called position dependent collection efficiency function which is defined as the probability that an electron-hole pair created at a certain point inside the solar cell will contribute to the current leaving the cell. (orig.) 15 refs.

  7. Source of a Prominent Poleward Surge During Solar Cycle 24

    CERN Document Server

    Yeates, A R; van Driel-Gesztelyi, L

    2015-01-01

    As an observational case study, we consider the origin of a prominent poleward surge of leading polarity, visible in the magnetic butterfly diagram during Solar Cycle 24. A new technique is developed for assimilating individual regions of strong magnetic flux into a surface flux transport model. By isolating the contribution of each of these regions, the model shows the surge to originate primarily in a single high-latitude activity group consisting of a bipolar active region present in Carrington Rotations 2104-05 (November 2010-January 2011) and a multipolar active region in Rotations 2107-08 (February-April 2011). This group had a strong axial dipole moment opposed to Joy's law. On the other hand, the modelling suggests that the transient influence of this group on the butterfly diagram will not be matched by a large long-term contribution to the polar field, because of its location at high latitude. This is in accordance with previous flux transport models.

  8. Life cycle assessment part 2: current impact assessment practice.

    Science.gov (United States)

    Pennington, D W; Potting, J; Finnveden, G; Lindeijer, E; Jolliet, O; Rydberg, T; Rebitzer, G

    2004-07-01

    Providing our society with goods and services contributes to a wide range of environmental impacts. Waste generation, emissions and the consumption of resources occur at many stages in a product's life cycle-from raw material extraction, energy acquisition, production and manufacturing, use, reuse, recycling, through to ultimate disposal. These all contribute to impacts such as climate change, stratospheric ozone depletion, photooxidant formation (smog), eutrophication, acidification, toxicological stress on human health and ecosystems, the depletion of resources and noise-among others. The need exists to address these product-related contributions more holistically and in an integrated manner, providing complimentary insights to those of regulatory/process-oriented methodologies. A previous article (Part 1, Rebitzer et al., 2004) outlined how to define and model a product's life cycle in current practice, as well as the methods and tools that are available for compiling the associated waste, emissions and resource consumption data into a life cycle inventory. This article highlights how practitioners and researchers from many domains have come together to provide indicators for the different impacts attributable to products in the life cycle impact assessment (LCIA) phase of life cycle assessment (LCA).

  9. CHIRALITY OF HIGH-LATITUDE FILAMENTS OVER SOLAR CYCLE 23

    Energy Technology Data Exchange (ETDEWEB)

    Yeates, A. R. [Department of Mathematical Sciences, Durham University, Durham, DH1 3LE (United Kingdom); Mackay, D. H., E-mail: anthony.yeates@durham.ac.uk, E-mail: duncan@mcs.st-and.ac.uk [School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS (United Kingdom)

    2012-07-10

    A non-potential quasi-static evolution model coupling the Sun's photospheric and coronal magnetic fields is applied to the problem of filament chirality at high latitudes. For the first time, we run a continuous 15 year simulation, using bipolar active regions determined from US National Solar Observatory, Kitt Peak magnetograms between 1996 and 2011. Using this simulation, we are able to address the outstanding question of whether magnetic helicity transport from active latitudes can overcome the effect of differential rotation at higher latitudes. Acting alone, differential rotation would produce high-latitude filaments with opposite chirality to the majority type in each hemisphere. We find that differential rotation can indeed lead to opposite chirality at high latitudes, but only for around 5 years of the solar cycle following the polar field reversal. At other times, including the rising phase, transport of magnetic helicity from lower latitudes overcomes the effect of in situ differential rotation, producing the majority chirality even on the polar crowns at polar field reversal. These simulation predictions will allow for future testing of the non-potential coronal model. The results indicate the importance of long-term memory and helicity transport from active latitudes when modeling the structure and topology of the coronal magnetic field at higher latitudes.

  10. Velocity fluctuations in polar solar wind: a comparison between different solar cycles

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2009-02-01

    Full Text Available The polar solar wind is a fast, tenuous and steady flow that, with the exception of a relatively short phase around the Sun's activity maximum, fills the high-latitude heliosphere. The polar wind properties have been extensively investigated by Ulysses, the first spacecraft able to perform in-situ measurements in the high-latitude heliosphere. The out-of-ecliptic phases of Ulysses cover about seventeen years. This makes possible to study heliospheric properties at high latitudes in different solar cycles. In the present investigation we focus on hourly- to daily-scale fluctuations of the polar wind velocity. Though the polar wind is a quite uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize wind velocity variations is that of performing a multi-scale statistical analysis of the wind velocity differences. Our analysis is based on the computation of velocity differences at different time lags and the evaluation of statistical quantities (mean, standard deviation, skewness, and kurtosis for the different ensembles. The results clearly show that, though differences exist in the three-dimensional structure of the heliosphere between the investigated solar cycles, the velocity fluctuations in the core of polar coronal holes exhibit essentially unchanged statistical properties.

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

    Science.gov (United States)

    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.

  12. Near-earth solar wind flows and related geomagnetic activity during more than four solar cycles (1963–2011

    Directory of Open Access Journals (Sweden)

    Richardson Ian G.

    2012-05-01

    Full Text Available 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 the related geomagnetic activity over more than four solar cycles, updating some of the results of our earlier studies.

  13. Radiating Current Sheets in the Solar Chromosphere

    CERN Document Server

    Goodman, Michael L

    2014-01-01

    An MHD model of a Hydrogen plasma with flow, an energy equation, NLTE ionization and radiative cooling, and an Ohm's law with anisotropic electrical conduction and thermoelectric effects is used to self-consistently generate atmospheric layers over a $50$ km height range. A subset of these solutions contain current sheets, and have properties similar to those of the lower and middle chromosphere. The magnetic field profiles are found to be close to Harris sheet profiles, with maximum field strengths $\\sim 25-150$ G. The radiative flux $F_R$ emitted by individual sheets is $\\sim 4.9 \\times 10^5 - 4.5 \\times 10^6$ ergs-cm$^{-2}$-s$^{-1}$, to be compared with the observed chromospheric emission rate of $\\sim 10^7$ ergs-cm$^{-2}$-s$^{-1}$. Essentially all emission is from regions with thicknesses $\\sim 0.5 - 13$ km containing the neutral sheet. About half of $F_R$ comes from sub-regions with thicknesses 10 times smaller. A resolution $\\lesssim 5-130$ m is needed to resolve the properties of the sheets. The sheets...

  14. Multiwavelength Study on Solar and Interplanetary Origins of the Strongest Geomagnetic Storm of Solar Cycle 23

    CERN Document Server

    Kumar, Pankaj; Uddin, Wahab

    2011-01-01

    We study the solar sources of an intense geomagnetic storm of solar cycle 23 that occurred on 20 November 2003, based on ground- and space-based multiwavelength observations. The coronal mass ejections (CMEs) responsible for the above geomagnetic storm originated from the super-active region NOAA 10501. We investigate the H-alpha observations of the flare events made with a 15 cm solar tower telescope at ARIES, Nainital, India. The propagation characteristics of the CMEs have been derived from the three-dimensional images of the solar wind (i.e., density and speed) obtained from the interplanetary scintillation data, supplemented with other ground- and space-based measurements. The TRACE, SXI and H-alpha observations revealed two successive ejections (of speeds ~350 and ~100 km/s), originating from the same filament channel, which were associated with two high speed CMEs (~1223 and ~1660 km/s, respectively). These two ejections generated propagating fast shock waves (i.e., fast drifting type II radio bursts) ...

  15. A Statistical Analysis of Solar Surface Indices Through the Solar Activity Cycles 21-23

    CERN Document Server

    Goker, Umit Deniz; Nutku, Ferhat; Priyal, Muthu

    2016-01-01

    Variations of total solar irradiance (TSI), magnetic field, Ca II K-flux, faculae and plage areas due to the number and the type of sunspots/sunspot groups (SGs) are well established by using ground based data from various centers such as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal data (KKL) and National Geographical Data Center (NGDC) Homepage, respectively. We applied time series analysis for extracting the data over the descending phases of solar activity cycles (SACs) 21, 22 and 23, and the ascending phases 22 and 23 of SACs, and analyzed the selected data using the Python programming language. Our detailed analysis results suggest that there is a stronger correlation between solar surface indices and the changes in the relative portion of the small and large SGs. This somewhat unexpected finding suggest that plage regions decreased in a lower values in spite of the higher number of large SGs in SAC 23 while Ca II K-flux did not decrease by large amount or it was comparable with SAC 22 for...

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

    Energy Technology Data Exchange (ETDEWEB)

    Bisoi, Susanta Kumar; Janardhan, P. [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India); Ingale, M.; Subramanian, P. [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411021 (India); Ananthakrishnan, S. [Department of Electronic Science, University of Pune, Pune 411007 (India); Tokumaru, M.; Fujiki, K., E-mail: susanta@prl.res.in, E-mail: jerry@prl.res.in, E-mail: i.madhusudan@students.iiserpune.ac.in, E-mail: p.subramanian@iiserpune.ac.in, E-mail: subra.anan@gmail.com, E-mail: tokumaru@stelab.nagoya-u.ac.jp, E-mail: fujiki@stelab.nagoya-u.ac.jp [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan)

    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.

  17. Probability density functions for the variable solar wind near the solar cycle minimum

    CERN Document Server

    Vörös,; Leitner, M; Narita, Y; Consolini, G; Kovács, P; Tóth, A; Lichtenberger, J

    2015-01-01

    Unconditional and conditional statistics is used for studying the histograms of magnetic field multi-scale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year 2008. The conditional statistics involves the magnetic field time series splitted 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 large-scale (B) and small-scale ({\\delta}B) 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, log-normal, kappa and logkappa functions. In a statistical sense the...

  18. Properties of the "island" structures of the background magnetic field in the 20th solar cycle.

    Science.gov (United States)

    Golub, P. A.

    It is shown that the "island" structure of the background magnetic field and sunspot groups has a common zone of localization and a common law of latitude drift with the phase of the 20th solar cycle. An important role of the "island" structure is noted in the formation of the 11 year solar cycle.

  19. Evidence of Suess solar-cycle bursts in Holocene speleothem d18O records

    DEFF Research Database (Denmark)

    Knudsen, Mads Faurschou; Jacobsen, B. H.; Riisager, Peter

    2012-01-01

    Several studies indicate that changes in solar activity may have driven Holocene subtropical monsoon variability on decadal and centennial timescales, but the strength and nature of this link remains debated. In this study, we combine a recent mapping of the Holocene solar-cycle activity with four...... in driving centennial-scale changes in the hydrological cycle in the subtropics during the Holocene....

  20. Reconstructing the 11-year solar cycle length from cosmogenic radionuclides for the last 600 years

    Science.gov (United States)

    Nilsson, Emma; Adolphi, Florian; Mekhaldi, Florian; Muscheler, Raimund

    2017-04-01

    The cyclic behavior of the solar magnetic field has been known for centuries and the 11-year solar cycle is one of the most important features directly visible on the solar disc. Using sunspot records it is evident that the length of this cycle is variable. A hypothesis of an inverse relationship between the average solar activity level and the solar cycle length has been put forward (e.g. Friis-Christensen & Lassen, 1991), indicating longer solar cycles during periods of low solar activity and vice versa. So far, studies of the behavior of the 11-year solar cycle have largely been limited for the last 4 centuries where observational sunspot data are available. However, cosmogenic radionuclides, such as 10Be and 14C from ice cores and tree rings allow an assessment of the strength of the open solar magnetic field due to its shielding influence on galactic cosmic rays in the heliosphere. Similarly, very strong solar storms can leave their imprint in cosmogenic radionuclide records via solar proton-induced direct production of cosmogenic radionuclides in the Earth atmosphere. Here, we test the hypothesis of an inverse relationship between solar cycle length and the longer-term solar activity level by using cosmogenic radionuclide records as a proxy for solar activity. Our results for the last six centuries suggest significant solar cycle length variations that could exceed the range directly inferred from sunspot records. We discuss the occurrence of SPEs within the 11-year solar cycle from a radionuclide perspective, specifically the largest one known yet, at AD 774-5 (Mekhaldi et al., 2015). References: Friis-Christensen, E. & Lassen, K. Length of the solar-cycle - An indicator of solar activity closely associated with climate. Science 254, 698-700, doi:10.1126/science.254.5032.698 (1991). Mekhaldi, F., Muscheler, R., Adolphi, F., Aldahan, A., Beer, J., McConnell, J. R., Possnert, G., Sigl, M., Svensson, A., Synal, H. A., Welten, K. C. & Woodruff, T. E

  1. Solar cycle and seasonal variations of the low latitude OI 630 nm nightglow

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Y.; Takahashi, H.; Bittencourt, J.A.; Sobral, J.H.A.; Teixeira, N.R.

    1988-02-01

    Regular zenith measurements of the OI 630 nm nightglow emission have been carried out at Cachoeira Paulista, Brazil, since 1975. The long series of observations during the period 1975-1982, including the ascending phase of the last solar cycle, permitted studies of solar cycle effects and seasonal variations. A large intensity increase, about seven times, from low solar activity to high solar activity has been observed. Also, the seasonal-nocturnal intensity variations show large changes between years of low and high solar activity. The characteristics of the variations observed are closely related to the equatorial electric field variations, since the observation site is under the southern equatorial ionospheric anomaly crest.

  2. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Török, T.; Titov, V. S.; Mikić, Z. [Predictive Science, Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Leake, J. E. [College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States); Archontis, V. [School of Mathematics and Statistics, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Linton, M. G. [U.S. Naval Research Lab, 4555 Overlook Avenue, SW Washington, DC 20375 (United States); Dalmasse, K.; Aulanier, G. [LESIA, Observatoire de Paris, CNRS, UPMC, Univ. Paris Diderot, 5 place Jules Janssen, F-92190 Meudon (France); Kliem, B. [Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Germany)

    2014-02-10

    There has been a long-standing debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After the region has formed and flux emergence has ceased, the strong magnetic fields in the region's center are connected solely by direct currents, and the total direct current is several times larger than the total return current. These results suggest that active regions, the main sources of coronal mass ejections and flares, are born with substantial net currents, in agreement with recent observations. Furthermore, they support eruption models that employ pre-eruption magnetic fields containing such currents.

  3. High-latitude Conic Current Sheets in the Solar Wind

    Science.gov (United States)

    Khabarova, Olga V.; Malova, Helmi V.; Kislov, Roman A.; Zelenyi, Lev M.; Obridko, Vladimir N.; Kharshiladze, Alexander F.; Tokumaru, Munetoshi; Sokół, Justyna M.; Grzedzielski, Stan; Fujiki, Ken'ichi

    2017-02-01

    We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.

  4. THE THERMAL PROPERTIES OF SOLAR FLARES OVER THREE SOLAR CYCLES USING GOES X-RAY OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, Daniel F.; Gallagher, Peter T. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Milligan, Ryan O.; Dennis, Brian R.; Kim Tolbert, A.; Schwartz, Richard A.; Alex Young, C. [Solar Physics Laboratory (Code 671), Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-10-15

    Solar flare X-ray emission results from rapidly increasing temperatures and emission measures in flaring active region loops. To date, observations from the X-Ray Sensor (XRS) on board the Geostationary Operational Environmental Satellite (GOES) have been used to derive these properties, but have been limited by a number of factors, including the lack of a consistent background subtraction method capable of being automatically applied to large numbers of flares. In this paper, we describe an automated Temperature and Emission measure-Based Background Subtraction method (TEBBS), that builds on the methods of Bornmann. Our algorithm ensures that the derived temperature is always greater than the instrumental limit and the pre-flare background temperature, and that the temperature and emission measure are increasing during the flare rise phase. Additionally, TEBBS utilizes the improved estimates of GOES temperatures and emission measures from White et al. TEBBS was successfully applied to over 50,000 solar flares occurring over nearly three solar cycles (1980-2007), and used to create an extensive catalog of the solar flare thermal properties. We confirm that the peak emission measure and total radiative losses scale with background subtracted GOES X-ray flux as power laws, while the peak temperature scales logarithmically. As expected, the peak emission measure shows an increasing trend with peak temperature, although the total radiative losses do not. While these results are comparable to previous studies, we find that flares of a given GOES class have lower peak temperatures and higher peak emission measures than previously reported. The TEBBS database of flare thermal plasma properties is publicly available at http://www.SolarMonitor.org/TEBBS/.

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    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 as- suming 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. Consid- ering the latest observed sunspot number so far available for cycle 23 and the pre- dictions for the minimum SMSN of cycle 24, a date calibration is done for the ob- tained time profiles, and thus, SMSNs for 127 months of cycle 24, from October 2007 to April 2018, are predicted.

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

    Institute of Scientific and Technical Information of China (English)

    WANG JiaLong; MIAO Juan; LIU SiQing; GONG JianCun; ZHU CuiLian

    2008-01-01

    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.

  7. The influence of spectral solar irradiance data on stratospheric heating rates during the 11 year solar cycle

    OpenAIRE

    Oberländer, S.; Langematz, U.; Matthes, Katja; Kunze, M; A. Kubin; J. Harder; N. A. Krivova; Solanki, S. K.; J. Pagaran; Weber, M.

    2012-01-01

    Heating rate calculations with the FUBRad shortwave (SW) radiation parameterization have been performed to examine the effect of prescribed spectral solar fluxes from the NRLSSI, MPS and IUP data sets on SW heating rates over the 11 year solar cycle 22. The corresponding temperature response is derived from perpetual January General Circulation Model (GCM) simulations with prescribed ozone concentrations. The different solar flux input data sets induce clear differences in SW heating rates at...

  8. Shannon Entropy-Based Prediction of Solar Cycle 25

    Science.gov (United States)

    Kakad, Bharati; Kakad, Amar; Ramesh, Durbha Sai

    2017-07-01

    A new model is proposed to forecast the peak sunspot activity of the upcoming solar cycle (SC) using Shannon entropy estimates related to the declining phase of the preceding SC. Daily and monthly smoothed international sunspot numbers are used in the present study. The Shannon entropy is the measure of inherent randomness in the SC and is found to vary with the phase of an SC as it progresses. In this model each SC with length T_{cy} is divided into five equal parts of duration T_{cy}/5. Each part is considered as one phase, and they are sequentially termed P1, P2, P3, P4, and P5. The Shannon entropy estimates for each of these five phases are obtained for the nth SC starting from n=10 - 23. We find that the Shannon entropy during the ending phase (P5) of the nth SC can be efficiently used to predict the peak smoothed sunspot number of the (n+1)th SC, i.e. S_{max}^{n+1}. The prediction equation derived in this study has a good correlation coefficient of 0.94. A noticeable decrease in entropy from 4.66 to 3.89 is encountered during P5 of SCs 22 to 23. The entropy value for P5 of the present SC 24 is not available as it has not yet ceased. However, if we assume that the fall in entropy continues for SC 24 at the same rate as that for SC 23, then we predict the peak smoothed sunspot number of 63±11.3 for SC 25. It is suggested that the upcoming SC 25 will be significantly weaker and comparable to the solar activity observed during the Dalton minimum in the past.

  9. Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

    Directory of Open Access Journals (Sweden)

    K. Semeniuk

    2011-05-01

    Full Text Available The impact of NOx and HOx production by three types of energetic particle precipitation (EPP, auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

  10. Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

    Directory of Open Access Journals (Sweden)

    K. Semeniuk

    2010-10-01

    Full Text Available The impact of NOx and HOx production by three types of energetic particle precipitation (EPP, aurora, solar proton events and galactic cosmic rays is examined using a chemistry climate model. Ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions were conducted for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10% in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4% more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

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

    Directory of Open Access Journals (Sweden)

    K. Scherer

    Full Text Available 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.

    Key words. Interplanetary

  12. Major Solar Eruptions and High Energy Particle Events during Solar Cycle 24

    CERN Document Server

    Gopalswamy, N; Akiyama, S; Makela, P; Yashiro, S

    2014-01-01

    We report on a study of all major solar eruptions that occurred on the front-side of the Sun during the rise to peak phase of cycle 24 (first 62 months) in order to understand the key factors affecting the occurrence of large solar energetic particle events (SEPs) and the ground levels enhancement (GLE) events. The eruptions involve major flares with soft X-ray peak flux >/= 5.0 x10-5 Wm-2 (i.e., flare size >/= M5.0) and accompanying coronal mass ejections (CMEs). The selection criterion was based on the fact that the only front-side GLE in cycle 24 (GLE 71) had a flare size of M5.1. Only ~37% of the major eruptions from the western hemisphere resulted in large SEP events. Almost the same number of large SEP events was produced in weaker eruptions (flare size

  13. Galactic and solar radiation exposure of aircrew over a solar cycle

    Energy Technology Data Exchange (ETDEWEB)

    Desormeaux, M

    2003-07-01

    For over a decade, research is being performed at the Royal Military College of Canada to evaluate the impact from cosmic radiation at various altitudes over the full magnetic field potential of the Earth (i.e., over all latitudes) and for any period in the solar cycle. This research has been encapsulated into a semi-empirical computer model termed the Predictive Code for Aircrew Radiation Exposure (PCAIRE). However, various improvements were desirable before the model could be used in an effective dose management program for aircrew exposure prediction. They included a more consistent way to analyze the data, and a better accounting of route dose measurements taken during low altitude flights, as well as during extreme solar modulation conditions. Finally, PCAIRE could not estimate the impact due to sporadic solar radiation events, which can significantly increase the total cosmic radiation exposure over a short period of time. As such, this thesis work concentrated on these model improvements, which were implemented into the latest version of the PCAIRE code (V7.2). (author)

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

    Science.gov (United States)

    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.

  15. Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima

    Science.gov (United States)

    Usoskin, I. G.; Gallet, Y.; Lopes, F.; Kovaltsov, G. A.; Hulot, G.

    2016-03-01

    Aims: Cosmogenic isotopes provide the only quantitative proxy for analyzing the long-term solar variability over a centennial timescale. While essential progress has been achieved in both measurements and modeling of the cosmogenic proxy, uncertainties still remain in the determination of the geomagnetic dipole moment evolution. Here we aim at improving the reconstruction of solar activity over the past nine millennia using a multi-proxy approach. Methods: We used records of the 14C and 10Be cosmogenic isotopes, current numerical models of the isotope production and transport in Earth's atmosphere, and available geomagnetic field reconstructions, including a new reconstruction relying on an updated archeo- and paleointensity database. The obtained series were analyzed using the singular spectrum analysis (SSA) method to study the millennial-scale trends. Results: A new reconstruction of the geomagnetic dipole field moment, referred to as GMAG.9k, is built for the last nine millennia. New reconstructions of solar activity covering the last nine millennia, quantified in terms of sunspot numbers, are presented and analyzed. A conservative list of grand minima and maxima is also provided. Conclusions: The primary components of the reconstructed solar activity, as determined using the SSA method, are different for the series that are based on 14C and 10Be. This shows that these primary components can only be ascribed to long-term changes in the terrestrial system and not to the Sun. These components have therefore been removed from the reconstructed series. In contrast, the secondary SSA components of the reconstructed solar activity are found to be dominated by a common ≈2400-year quasi-periodicity, the so-called Hallstatt cycle, in both the 14C and 10Be based series. This Hallstatt cycle thus appears to be related to solar activity. Finally, we show that the grand minima and maxima occurred intermittently over the studied period, with clustering near lows and highs

  16. Constraining neutrino oscillation parameters with current solar and atmospheric data

    CERN Document Server

    Maltoni, M; Tortola, M A; Valle, José W F

    2003-01-01

    We analyse the impact of recent solar and atmospheric data in the determination of the neutrino oscillation parameters, taking into account that both the solar nu_e and the atmospheric nu_mu may convert to a mixture of active and sterile neutrinos. In addition to the recent SNO neutral current (NC), spectral and day/night data we add the latest 1496-day solar and 1489-day atmospheric Super-K neutrino data samples. By investigating in detail the impact of the recent SNO NC, spectral and day/night data, we confirm the clear preference of the LMA solution of the solar neutrino problem and obtain that the LOW, VAC, SMA solutions are disfavoured with a Delta_chi^2 = 9, 9, 23, respectively. Furthermore, we find that the global solar data constrains the admixture of a sterile neutrino to be less than 45% at 99% CL. A pure sterile solution is ruled out with respect to the active one at 99.996% CL. By performing an improved fit of the atmospheric data, we also update the corresponding regions of oscillation parameters...

  17. New approaches to business cycle theory in current economic science

    Directory of Open Access Journals (Sweden)

    Monica DOBRESCU

    2012-07-01

    Full Text Available In modern economies, current research generally acknowledges that the central issues in macroeconomics are essentially the same as those identified by Keynes in the General Theory of Employment, Interest and Money. One way or the other, economists are trying to address the same macroeconomic issues that they did seven decades ago: How can we account for the different growth rates and various fluctuations observed in national economies? Which are the economic policies most suitable to solve the issues of growth and cyclic behavior? Both the new classicals and the new Keynesians have made considerable progress within their research paradigms: to explain economic fluctuations, the new classicals focus on technological perturbations, the intertemporal substitution of leisure and real business cycles; on the other hand, the new Keynesians speak in terms of monopolistic competition, menu costs or efficiency wages. On the whole, the new classicals believe that the business cycle can best be understood within the market-clearing model, whereas the new keynesians believe that business fluctuations are due to certain market failures of various sorts.The present paper focuses on the main directions of research of the new classical school on the business cycle, given that the theoretical progress in this field has been significant and relevant for economic policy during the past four decades.

  18. Performance analysis a of solar driven organic Rankine cycle using multi-component working fluids

    DEFF Research Database (Denmark)

    Baldasso, E.; Andreasen, J. G.; Modi, A.

    2015-01-01

    Among the different renewable sources of energy, solar power could play a primary role in the development of a more sustainable electricity generation system. While large scale concentrated solar power plants based on the steam Rankine cycle have already been proved to be cost effective, research...... cycle. The purpose of this paper is to optimize a low temperature organic Rankine cycle tailored for solar applications. The objective of the optimization is the maximization of the solar to electrical efficiency and the optimization parameters are the working fluid and the turbine inlet temperature...... is still under progress for small scale low temperature solar-driven power plants. The steam Rankine cycle is suitable for high temperature applications, but its efficiency drastically decreases as the heat source temperature drops. In these cases a much more promising configuration is the organic Rankine...

  19. Current blocking and current collection in CIGSe solar cells depending on sodium content

    Energy Technology Data Exchange (ETDEWEB)

    Puttnins, Stefan; Daume, Felix [Solarion AG, Leipzig (Germany); Institut fuer Experimentelle Physik II, Universitaet Leipzig (Germany); Zachmann, Hendrik; Rahm, Andreas [Solarion AG, Leipzig (Germany); Grundmann, Marius [Institut fuer Experimentelle Physik II, Universitaet Leipzig (Germany)

    2010-07-01

    IV-curves of thin film solar cells often show non-idealites like voltage dependent carrier collection and current blocking behaviour. Sodium is long known to improve the efficiency of Cu(In,Ga)Se{sub 2} solar cells by increasing V{sub OC} and FF. However, the way in which sodium influences the electrical properties is still under discussion. We investigated the influence of sodium on voltage dependent carrier collection and current blocking behaviour. Losses caused by incomplete photocurrent collection can be reduced by increased sodium content in the CIGSe layer. Current blocking behaviour like the rollover effect is less pronounced with increased sodium content. The influences were analyzed both in detailed illumination intensity and temperature dependent IV-measurements as well as by extensive statistical analysis over thousands of produced flexible CIGSe solar cells. Theoretical models for this dependency were simulated with SCAPS-1D and show good agreement with respective measurements.

  20. Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles

    CERN Document Server

    Kilcik, A; Abramenko, V; Goode, P R; Ozguc, A; Rozelot, J P; Cao, W; 10.1088/0004-637X/731/1/30

    2011-01-01

    Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 2023 by using Rome (cycles 2021) and Learmonth Solar Observatory (cycles 2223) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification) and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for the solar cycle 22. In general large SG numbers appear to reach their maximum in the middle of the solar cycle (phase 0.450.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phase 0.290.35). Moreover, the 10.7 cm solar radio flux, the facul...

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

    Science.gov (United States)

    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.

  2. Integrated solar combined cycles using gas turbines with partial recuperation and solar integration at different pressure levels

    Science.gov (United States)

    Rovira, Antonio; Sánchez, Consuelo; Fernández, Santiago; Muñoz, Marta; Barbero, Rubén

    2017-06-01

    This work studies and compares two alternatives to improve the solar-to-electricity energy conversion efficiency in integrated solar combined cycle power plants (ISCC), which are based on the use of combined cycles including partial recuperative gas turbines. Each alternative has been integrated into dual and triple pressure levels with reheat heat recovery steam generators (HRSG). Partial recuperation conveys lower heat recovery at the steam generator than in conventional plants, because each MW exchanged in the recuperator is not available at the HRSG. This thermal power decrease at the HRSG may be overcome by the integration of solar energy that is implemented using parabolic trough collectors. Moreover, with such an implementation each solar thermal MW integrated allows a MW of heat recuperation and, thus a MW of fossil fuel saving, thus the solar heat-to-electricity energy conversion rate may reach values up to 50 %, which makes the proposal interesting.

  3. Orphan drugs in development for urea cycle disorders: current perspectives

    Directory of Open Access Journals (Sweden)

    Häberle J

    2014-09-01

    Full Text Available Johannes Häberle,1 Shawn E McCandless2 1Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland; 2Center for Human Genetics, University Hospitals Case Medical Center, and Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA Abstract: The urea cycle disorders are caused by deficiency of one of the six hepatic enzymes or two transporters involved in detoxification of ammonia. The resulting hyperammonemia causes severe brain injury unless aggressive steps are taken to reduce the accumulation of ammonia, which is thought to be the most toxic metabolite. This review describes the current state of chronic management of urea cycle disorders, focusing on new and emerging therapies. Management strategies include the mainstay of treatment, namely dietary protein restriction and supplementation with l-arginine or l-citrulline. Several currently approved medications utilize and enhance alternative pathways of waste nitrogen excretion (sodium benzoate, sodium phenylacetate, sodium phenylbutyrate in several formulations, and glycerol phenylbutyrate, working through conjugation of the drug to either glycine (in the case of benzoate or glutamine, the products of which are excreted in the urine. Carglumic acid activates the first committed step of conversion of ammonia to urea, carbamoylphosphate synthetase, and thus effectively treats defective synthesis of the endogenous activator, N-acetylglutamate, whether due to genetic defects or biochemical inhibition of the N-acetylglutamate synthase enzyme. Approaches to neuroprotection during episodes of hyperammonemia are discussed, including the use of controlled hypothermia (brain cooling, as well as proposed, but as yet untested, pharmacologic therapies. Finally, cell-based therapies, including liver transplantation, infusion of fresh or cryopreserved hepatocytes, use of stem cells, and new approaches to gene

  4. Flexible thermal cycle test equipment for concentrator solar cells

    Science.gov (United States)

    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.

  5. Analysis and optimization of the low-temperature solar organic Rankine cycle (ORC)

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Torres, Agustin M. [Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas, Escuela Tecnica Superior de Ingenieria Civil e Industrial, Universidad de La Laguna (ULL), Avda, Astrofisico Francisco Sanchez s/n, 38206 La Laguna, Tenerife (Spain); Garcia-Rodriguez, Lourdes [Dpto. Ingenieria Energetica, Escuela Tecnica Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos, s/n 41092 Sevilla (Spain)

    2010-12-15

    Solar thermal driven reverse osmosis desalination is a promising renewable energy-driven desalination technology. A joint use of the solar thermal powered organic Rankine cycle (ORC) and the desalination technology of less energy consumption, reverse osmosis (RO), makes this combination interesting in some scarce water resource scenarios. However, prior to any practical experience with any new process, a comprehensive and rigorous theoretical study must be done in order to assess the performance of the new technology or combination of existing technologies. The main objective of the present paper is the expansion of the theoretical analysis done by the authors in previous works to the case in which the thermal energy required by a solar ORC is supplied by means of stationary solar collectors. Twelve substances are considered as working fluids of the ORC and four different models of stationary solar collectors (flat plate collectors, compound parabolic collectors and evacuated tube collectors) are also taken into account. Operating conditions of the solar ORC that minimizes the aperture area needed per unit of mechanical power output of the solar cycle are determined for every working fluid and every solar collector. The former is done considering a direct vapour generation configuration of the solar cycle and also the configuration with water as heat transfer fluid flowing inside the solar collector. This work is part of the theoretical analysis of the solar thermal driven seawater and brackish water reverse osmosis desalination technology. Nevertheless, the supplied information can be also used for the assessment of different applications of the solar ORC. In that case, results presented in this paper can be useful in techno-economic analysis, selection of working fluids of the Rankine cycle, sizing of systems and assessment of solar power cycle configuration. (author)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Propagation of Coronal Mass Ejections Observed During the Rising Phase of Solar Cycle 24

    Science.gov (United States)

    Syed Ibrahim, M.; Manoharan, P. K.; Shanmugaraju, A.

    2017-09-01

    In this study, we investigate the interplanetary consequences and travel time details of 58 coronal mass ejections (CMEs) in the Sun-Earth distance. The CMEs considered are halo and partial halo events of width {>} 120°. These CMEs occurred during 2009 - 2013, in the ascending phase of the Solar Cycle 24. Moreover, they are Earth-directed events that originated close to the centre of the solar disk (within about ±30° from the Sun's centre) and propagated approximately along the Sun-Earth line. For each CME, the onset time and the initial speed have been estimated from the white-light images observed by the LASCO coronagraphs onboard the SOHO space mission. These CMEs cover an initial speed range of {˜} 260 - 2700 km s^{-1}. For these CMEs, the associated interplanetary shocks (IP shocks) and interplanetary CMEs (ICMEs) at the near-Earth environment have been identified from in-situ solar wind measurements available at the OMNI data base. Most of these events have been associated with moderate to intense IP shocks. However, these events have caused only weak to moderate geomagnetic storms in the Earth's magnetosphere. The relationship of the travel time with the initial speed of the CME has been compared with the observations made in the previous Cycle 23, during 1996 - 2004. In the present study, for a given initial speed of the CME, the travel time and the speed at 1 AU suggest that the CME was most likely not much affected by the drag caused by the slow-speed dominated heliosphere. Additionally, the weak geomagnetic storms and moderate IP shocks associated with the current set of Earth-directed CMEs indicate magnetically weak CME events of Cycle 24. The magnetic energy that is available to propagate CME and cause geomagnetic storm could be significantly low.

  10. Seasonal, Diurnal, and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2012-01-01

    Full Text Available We analyse the variability of foF2 at two West Africa equatorial ionization anomaly stations (Ouagadougou and Dakar during three solar cycles (from cycle 20 to cycle 22, that is, from 1966 to 1998 for Ouagadougou and from 1971 to 1997 for Dakar. We examine the effect of the changing levels of solar extreme ultraviolet radiation with sunspot number. The study shows high correlation between foF2 and sunspot number (Rz. The correlation coefficient decreases from cycle 20 to cycle 21 at both stations. From cycle 21 to cycle 22 it decreases at Ouagadougou station and increases at Dakar station. The best correlation coefficient, 0.990, is obtained for Dakar station during solar cycle 22. The seasonal variation displays equinoctial peaks that are asymmetric between March and September. The percentage deviations of monthly average data from one solar cycle to another display variability with respect to solar cycle phase and show solar ultraviolet radiation variability with solar cycle phase. The diurnal variation shows a noon bite out with a predominant late-afternoon peak except during the maximum phase of the solar cycle. The diurnal Ouagadougou station foF2 data do not show a significant difference between the increasing and decreasing cycle phases, while Dakar station data do show it, particularly for cycle 21. The percentage deviations of diurnal variations from solar-minimum conditions show more ionosphere during solar cycle 21 at both stations for all three of the other phases of the solar cycle. There is no significant variability of ionosphere during increasing and decreasing solar cycle phases at Ouagadougou station, but at Dakar station there is a significant variability of ionosphere during these two solar-cycle phases.

  11. Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA

    Directory of Open Access Journals (Sweden)

    Zender Joe

    2012-08-01

    Full Text Available The Large-Yield Radiometer (LYRA is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy, have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this paper, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE. We find that the solar EUV irradiance has increased by a factor of 2 since the last solar minimum (between solar cycles 23 and 24, which agrees reasonably well with the EVE observations.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 ISEE-3 during the period spanning the maxima of cycles 21 and 22.

  14. Stand-Alone Solar Organic Rankine Cycle Water Pumping System and Its Economic Viability in Nepal

    Directory of Open Access Journals (Sweden)

    Suresh Baral

    2015-12-01

    Full Text Available The current study presents the concept of a stand-alone solar organic Rankine cycle (ORC water pumping system for rural Nepalese areas. Experimental results for this technology are presented based on a prototype. The economic viability of the system was assessed based on solar radiation data of different Nepalese geographic locations. The mechanical power produced by the solar ORC is coupled with a water pumping system for various applications, such as drinking and irrigation. The thermal efficiency of the system was found to be 8% with an operating temperature of 120 °C. The hot water produced by the unit has a temperature of 40 °C. Economic assessment was done for 1-kW and 5-kW solar ORC water pumping systems. These systems use different types of solar collectors: a parabolic trough collector (PTC and an evacuated tube collector (ETC. The economic analysis showed that the costs of water are $2.47/m3 (highest and $1.86/m3 (lowest for the 1-kW system and a 150-m pumping head. In addition, the cost of water is reduced when the size of the system is increased and the pumping head is reduced. The minimum volumes of water pumped are 2190 m3 and 11,100 m3 yearly for 1 kW and 5 kW, respectively. The payback period is eight years with a profitability index of 1.6. The system is highly feasible and promising in the context of Nepal.

  15. Current Collecting Grids for ITO-Free Solar Cells

    DEFF Research Database (Denmark)

    Galagan, Yulia; Zimmermann, Birger; Coenen, Erica W. C.

    2012-01-01

    enabling the identification of the most rational grid structure is presented. Both optical and light beam induced current (LBIC) mapping of the devices are used to support the power loss model and to follow the evolution of the performance over time. Current generation is found to be evenly distributed......Indium-tin-oxide (ITO) free polymer solar cells prepared by ink jet printing a composite front electrode comprising silver grid lines and a semitransparent PEDOT:PSS conductor are demonstrated. The effect of grid line density is explored for a large series of devices and a careful modeling study...

  16. Mini Solar and Sea Current Power Generation System

    Science.gov (United States)

    Almenhali, Abdulrahman; Alshamsi, Hatem; Aljunaibi, Yaser; Almussabi, Dheyab; Alshehhi, Ahmed; Hilal, Hassan Bu

    2017-07-01

    The power demand in United Arab Emirates is increased so that there is a consistent power cut in our region. This is because of high power consumption by factories and also due to less availability of conventional energy resources. Electricity is most needed facility for the human being. All the conventional energy resources are depleting day by day. So we have to shift from conventional to non-conventional energy resources. In this the combination of two energy resources is takes place i.e. wind and solar energy. This process reviles the sustainable energy resources without damaging the nature. We can give uninterrupted power by using hybrid energy system. Basically this system involves the integration of two energy system that will give continuous power. Solar panels are used for converting solar energy and wind turbines are used for converting wind energy into electricity. This electrical power can utilize for various purpose. Generation of electricity will be takes place at affordable cost. This paper deals with the generation of electricity by using two sources combine which leads to generate electricity with affordable cost without damaging the nature balance. The purpose of this project was to design a portable and low cost power system that combines both sea current electric turbine and solar electric technologies. This system will be designed in efforts to develop a power solution for remote locations or use it as another source of green power.

  17. CURRENT TRENDS IN THE USE OF SOLAR ENERGY

    Directory of Open Access Journals (Sweden)

    Vanya Zhivkova

    2013-06-01

    Full Text Available Solar energy represents the amount of solar radiation per unit time on unit area. Solar energy is used to obtain thermal energy through solar, and electrical energy through exist for solar energy: passive and active. The utilization of solar energy is essential for the development of human civilization.

  18. Influence of solar luminosity over geomagnetic and climatic cycles as derived from speleothems

    Directory of Open Access Journals (Sweden)

    Shopov Yavor Y.

    2004-12-01

    Full Text Available We observed cycles presented in a luminescent solar insolation proxy record from a speleothem from Jewel Cave, South Dakota, US. We found cycles of orbital precession with periods of 23 and 19 ka and of obliquity of 41 ka and many others from non- orbital origin in this sample. We determined the Solar origin of the cycles with durations of11500, 4400, 3950, 2770, 2500, 2090, 1960, 1670, 1460, 1280, 1195, 1145, 1034, 935, 835, 750 and 610 years. It was done by their detection both in proxy records of speleothem luminescence, D14C and the intensity of the geomagnetic dipole. It is well known that the main variations in the last two records are produced by the solar wind.The most intensive cycle discovered in this record has duration of 11.5 ka. It is not of orbital origin. It was found previously to be the most intensive cycle in the D14C calibration record and has been interpreted to be of terrestrial origin because “it is too strong tobe of solar origin”. Our studies suggest that it should be a solar cycle modulating the geomagnetic field and 14C reversed production as the other solar cycles do.

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

    Science.gov (United States)

    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

  20. Heliospheric current sheet and its interaction with solar cosmic rays

    Science.gov (United States)

    Malova, Helmi; Popov, Victor; Grigorenko, Elena; Dunko, Andrey; Petrukovich, Anatoly

    2016-04-01

    We investigated effects resulting from the interaction of solar cosmic rays (SCR) with the heliospheric current sheet (HCS) in the solar wind. Self-consistent kinetic model of the HCS is developed, where ions demonstrate quasi-adiabatic dynamics. HCS is considered as the equilibrium embedded current structure, where the two main kinds of plasma with different temperatures give the main contribution to the current (low-energy background plasma and SCR). It is shown that HCS is a relatively thin multiscale configuration of the current sheet, embedded in a thicker plasma layer. The taking into account of SCR particles in HCS could lead to a change of its structure and to enhancement of its properties such as the embedding and multi-scaling. Parametric family of solutions is considered where the current balance in HCS is provided at different temperatures of SCR and different concentrations of high-energy plasma. Concentrations of SCR are determined which may contribute to the thickening of the HCS that can be observed in satellite studies. The possibility to apply this modeling for the explanation of experimental observations is considered.

  1. Simulating the Outer Radiation Belt During the Rising Phase of Solar Cycle 24

    Science.gov (United States)

    Fok, Mei-Ching; Glocer, Alex; Zheng, Qiuhua; Chen, Sheng-Hsien; Kanekal, Shri; Nagai, Tsungunobu; Albert, Jay

    2011-01-01

    After prolonged period of solar minimum, there has been an increase in solar activity and its terrestrial consequences. We are in the midst of the rising phase of solar cycle 24, which began in January 2008. During the initial portion of the cycle, moderate geomagnetic storms occurred follow the 27 day solar rotation. Most of the storms were accompanied by increases in electron fluxes in the outer radiation belt. These enhancements were often preceded with rapid dropout at high L shells. We seek to understand the similarities and differences in radiation belt behavior during the active times observed during the of this solar cycle. This study includes extensive data and simulations our Radiation Belt Environment Model. We identify the processes, transport and wave-particle interactions, that are responsible for the flux dropout and the enhancement and recovery.

  2. Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2006-12-01

    Full Text Available We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1 The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2 The magnitude of negative Bzmin is larger in a solar active period than in a quiet period. (3 Solar wind speed in an active period is faster than in a quiet period. (4 VBsmax in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6 Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax with geomagnetic storm intensity during a solar quiet period. (7 The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8 More severe storms with Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

  3. Thermoeconomic optimization of a Kalina cycle for a central receiver concentrating solar power plant

    DEFF Research Database (Denmark)

    Modi, Anish; Kærn, Martin Ryhl; Andreasen, Jesper Graa

    2016-01-01

    Concentrating solar power plants use a number of reflecting mirrors to focus and convert the incident solar energy to heat, and a power cycle to convert this heat into electricity. This paper evaluates the use of a high temperature Kalina cycle for a central receiver concentrating solar power plant...... with direct vapour generation and without storage. The use of the ammonia-water mixture as the power cycle working fluid with non-isothermal evaporation and condensation presents the potential to improve the overall performance of the plant. This however comes at a price of requiring larger heat exchangers...... and the economic perspectives, the results suggest that it is not beneficial to use the Kalina cycle for high temperature concentrating solar power plants....

  4. Neutral density variation from specular meteor echo observations spanning one solar cycle

    Science.gov (United States)

    Stober, G.; Matthias, V.; Brown, P.; Chau, J. L.

    2014-10-01

    Specular meteor radars have provided essential information about the mesospheric/lower thermosphere (MLT) dynamics. The Canadian Meteor Orbit Radar has been conducting continuous meteor echo observations in a fixed, stable configuration since 2002. Here we present estimates of the neutral air density variations derived from observations of the meteor peak flux altitude. Using a simple model assuming a linear trend and a sinusoidal solar cycle we derived a trend of a decreasing neutral density of 5.8 ± 1.1% per decade at approximately 91 km altitude and an amplitude across the most recent solar cycle, the solar cycle of 2.4 ± 0.7% for solar cycle 23/24. The long-term trend of decreasing neutral air density in the MLT is in good agreement with the model results from Akmaev et al. (2006).

  5. Synchronized Helicity Oscillations: A Link Between Planetary Tides and the Solar Cycle?

    Science.gov (United States)

    Stefani, F.; Giesecke, A.; Weber, N.; Weier, T.

    2016-10-01

    Recent years have seen an increased interest in the question of whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we examine which possible physical mechanism might link the weak planetary forces with solar dynamo action. We focus on the helicity oscillations that were recently found in simulations of the current-driven, kink-type Tayler instability, which is characterized by an m=1 azimuthal dependence. We show how these helicity oscillations may be resonantly excited by some m=2 perturbations that reflect a tidal oscillation. Specifically, we speculate that the tidal oscillation of 11.07 years induced by the Venus-Earth-Jupiter system may lead to a 1:1 resonant excitation of the oscillation of the α-effect. Finally, we recover a 22.14-year cycle of the solar dynamo in the framework of a reduced zero-dimensional α-Ω dynamo model.

  6. Modeling of the Radiation Belt Dynamics During the Two Largest Geomagnetic Storms of Solar Cycle 24

    Science.gov (United States)

    Zheng, Y.; Rastaetter, L.; Kuznetsova, M. M.

    2016-12-01

    In this paper, radiation belt response to the two largest geomagnetic storms of Solar Cycle 24 (17 March 2015 and the 22 June 2015) is investigated in detail. Even though both storms are primarily CME driven, each has its own complexities [Liu et al., 2015, Kataoka et al., 2015]. Using the CCMC's run-on-request system, modeling results using the RBE (Radiation Belt Environment) model within the SWMF (Space Weather Modeling Framework) and the RBE model coupled with the SWMF and RCM (Rice Convection Model, which takes the ring current's contribution into consideration) will be examined. Comparative and comprehensive analyses of the same event from two different models and of two events from the same model/model suite will be provided. Focus will be specially given to impacts of different solar wind drivers on radiation belt dynamics and to the coupling and interactions of different plasma populations/physical processes within the region. Liu, Ying D., H. Hu, R. Wang, Z. Yang, B., Zhu, Y. A., Liu, J. G. Luhmann, J. D. Richardson (2015), Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability, The Astrophysical Journal Letters, Volume 809, Issue 2, article id. L34, 6 pp. doi:10.1088/2041-8205/809/2/L34. Kataoka, R., D. Shiota, E. Kilpua, and K. Keika (2015), Pileup accident hypothesis of magnetic storm on 17 March 2015, Geophys. Res. Lett., 42, 5155-5161, doi:10.1002/2015GL064816.

  7. Synchronized helicity oscillations: a link between planetary tides and the solar cycle?

    CERN Document Server

    Stefani, F; Weber, N; Weier, T

    2015-01-01

    Recent years have seen an increased interest in the question whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we ask for a possible physical mechanism which might link the weak planetary forces with solar dynamo action. We focus on the helicity oscillations which were recently found in simulations of the current-driven, kink-type Tayler instability which is characterized by an m=1 azimuthal dependence. We show how these helicity oscillations can be resonantly excited by some m=2 perturbation that reflects a tidal oscillation. Specifically, we speculate that the 11.07 years tidal oscillation induced by the Venus-Earth-Jupiter system may lead to a 1:1 resonant excitation of the oscillation of the alpha effect. Finally, in the framework of a reduced, zero-dimensional alpha-Omega dynamo model we recover a 22.14 years cycle of the solar dynamo.

  8. Synchronized Helicity Oscillations: A Link Between Planetary Tides and the Solar Cycle?

    Science.gov (United States)

    Stefani, F.; Giesecke, A.; Weber, N.; Weier, T.

    2016-09-01

    Recent years have seen an increased interest in the question of whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we examine which possible physical mechanism might link the weak planetary forces with solar dynamo action. We focus on the helicity oscillations that were recently found in simulations of the current-driven, kink-type Tayler instability, which is characterized by an m=1 azimuthal dependence. We show how these helicity oscillations may be resonantly excited by some m=2 perturbations that reflect a tidal oscillation. Specifically, we speculate that the tidal oscillation of 11.07 years induced by the Venus-Earth-Jupiter system may lead to a 1:1 resonant excitation of the oscillation of the α-effect. Finally, we recover a 22.14-year cycle of the solar dynamo in the framework of a reduced zero-dimensional α- Ω dynamo model.

  9. A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations

    Science.gov (United States)

    Brooks, David H.; Baker, Deborah; van Driel-Gesztelyi, Lidia; Warren, Harry P.

    2017-08-01

    The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, to show that when the Sun is observed as a star, the variation of coronal composition is highly correlated with a proxy for solar activity, the F10.7 cm radio flux, and therefore with the solar cycle phase. Similar cyclic variations should therefore be detectable spectroscopically in X-ray observations of solar analogs. The plasma composition in full-disk observations of the Sun is related to the evolution of coronal magnetic field activity. Our observations therefore introduce an uncertainty into the nature of any relationship between coronal composition and fixed stellar properties. The results highlight the importance of systematic full-cycle observations for understanding the elemental composition of solar-like stellar coronae.

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

    CERN Document Server

    Barekat, Atefeh; Gizon, Laurent

    2016-01-01

    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 ($\\rm d\\ln\\Omega/\\rm d\\ln r $) in the upper 10~Mm is close to $-1$ from the equator to $60^\\circ$ latitude.We aim to measure the temporal variation of the rotational shear over solar cycle 23 and the rising phase of cycle 24 (1996-2015). 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 $\\rm d\\ln\\Omega/d\\ln r $ from the equator to $80^\\circ$ 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. We found the rotational shear at low latitudes ($0^\\circ$ to $30^...

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

  14. Catalogue of 55-80 MeV solar proton events extending through solar cycles 23 and 24

    Science.gov (United States)

    Paassilta, Miikka; Raukunen, Osku; Vainio, Rami; Valtonen, Eino; Papaioannou, Athanasios; Siipola, Robert; Riihonen, Esa; Dierckxsens, Mark; Crosby, Norma; Malandraki, Olga; Heber, Bernd; Klein, Karl-Ludwig

    2017-06-01

    We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the Solar and Heliospheric Observatory/the Energetic and Relativistic Nuclei and Electron experiment (SOHO/ERNE). In addition to ERNE proton and heavy ion observations, data from the Advanced Composition Explorer/Electron, Proton and Alpha Monitor (ACE/EPAM) (near-relativistic electrons), SOHO/EPHIN (Electron Proton Helium Instrument) (relativistic electrons), SOHO/LASCO (Large Angle and Spectrometric Coronagraph) (coronal mass ejections, CMEs) and Geostationary Operational Environmental Satellite (GOES) soft X-ray experiments are also considered and the associations between the particle and CME/X-ray events deduced to obtain a better understanding of each event. A total of 176 solar energetic particle (SEP) events have been identified as having occurred during the time period of interest; their onset and solar release times have been estimated using both velocity dispersion analysis (VDA) and time-shifting analysis (TSA) for protons, as well as TSA for near-relativistic electrons. Additionally, a brief statistical analysis was performed on the VDA and TSA results, as well as the X-rays and CMEs associated with the proton/electron events, both to test the viability of the VDA and to investigate possible differences between the two solar cycles. We find, in confirmation of a number of previous studies, that VDA results for protons that yield an apparent path length of 1 AU type CMEs. Taken together, these observations point to a qualitative difference between the two solar cycles.

  15. Anomalous Surge of the White-Light Corona at the Onset of the Declining Phase of Solar Cycle 24

    Science.gov (United States)

    Lamy, P.; Boclet, B.; Wojak, J.; Vibert, D.

    2017-04-01

    In late 2014, when the current Solar Cycle 24 entered its declining phase, the white-light corona as observed by the LASCO-C2 coronagraph underwent an unexpected surge that increased its global radiance by 60%, reaching a peak value comparable to the peak values of the more active Solar Cycle 23. A comparison of the temporal variation of the white-light corona with the variations of several indices and proxies of solar activity indicate that it best matches the variation of the total magnetic field. The daily variations point to a localized enhancement or bulge in the electron density that persisted for several months. Carrington maps of the radiance and of the HMI photospheric field allow connecting this bulge to the emergence of the large sunspot complex AR 12192 in October 2014, the largest since AR 6368 observed in November 1990. The resulting unusually high increase of the magnetic field and the distortion of the neutral sheet in a characteristic inverse S-shape caused the coronal plasma to be trapped along a similar pattern. A 3D reconstruction of the electron density based on time-dependent solar rotational tomography supplemented by 2D inversion of the coronal radiance confirms the morphology of the bulge and reveals that its level was well above the standard models of a corona of the maximum type, by typically a factor of 3. A rather satisfactory agreement is found with the results of the thermodynamic MHD model produced by Predictive Sciences, although discrepancies are noted. The specific configuration of the magnetic field that led to the coronal surge resulted from the interplay of various factors prevailing at the onset of the declining phase of the solar cycles, which was particularly efficient in the case of Solar Cycle 24.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  18. Estimates of the neutron emission during large solar flares in the rising and maximum period of solar cycle 24

    Science.gov (United States)

    Lopez, D.; Matsubara, Y.; Muraki, Y.; Sako, T.; Valdés-Galicia, J. F.

    2016-03-01

    We searched for solar neutrons using the data collected by six detectors from the International Network of Solar Neutron Telescopes and one Neutron Monitor between January 2010 and December 2014. We considered the peak time of the X-ray intensity of thirty five ≥ X1.0 class flares detected by GOES satellite as the most probable production time of solar neutrons. We prepared a light-curve of the solar neutron telescopes and the neutron monitor for each flare, spanning ± 3 h from the peak time of GOES. Based on these light curves, we performed a statistical analysis for each flare. Setting a significance level at greater than 3σ, we report that no statistically significant signals due to solar neutrons were found. Therefore, upper limits are determined by the background level and solar angle of these thirty five solar flares. Our calculation assumed a power-law neutron energy spectrum and an impulsive emission profile at the Sun. The estimated upper limits of the neutron emission are consistent within the order of magnitude of the successful detections of solar neutrons made in solar cycle 23.

  19. Interdigitated back contact solar cell with high-current collection

    Science.gov (United States)

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    Internal current collection efficiencies greater than 90% and energy conversion efficiencies of 18 % at 30 suns were measured on a laboratory version of the interdigitated back contact (IBC) solar cell. A phosphorous gettering diffusion was performed on the front surface and then etched off to achieve these high current collection efficiencies. Thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. It is suggested that this should result in higher efficiencies at high concentration.

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

    CERN Document Server

    Dasi-Espuig, Maria; Krivova, Natasha A; Cameron, Robert H; Peñuela, Tania

    2010-01-01

    It is 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 another. 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 with the strength of the next cycle. 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 predictions of solar activity. We employ 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, amplitude and length. The two main results are: 1. An anti-correlation between the m...

  1. Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-04-01

    Full Text Available The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle and solar-to-fuel energy conversion efficiency (ηsolar−to−fuel attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar−to−fuel both increase with decreasing TH, due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore, the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance, in the case where TH = 2280 K, ηcycle = 24.4% and ηsolar−to−fuel = 29.5% (without heat recuperation, while ηcycle = 31.3% and ηsolar−to−fuel = 37.8% (with 40% heat recuperation.

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

    Science.gov (United States)

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

    2015-09-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Herdiwijaya, Dhani, E-mail: dhani@as.itb.ac.id [Astronomy Research Division and Bosscha Observatory, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia); Arif, Johan [Geology Research Division, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia); Nurzaman, Muhamad Zamzam; Astuti, Isna Kusuma Dewi [Astronomy Study Program, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung, Indonesia 40132 (Indonesia)

    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.

  4. Radial and Solar Cycle Variations of the Magnetic Fields in the Heliosheath: Voyager 1 Observations from 2005 to 2008

    Science.gov (United States)

    Burlaga, Leonard; Ness, N.

    2009-01-01

    We discuss the magnetic field strength B(t) and polarity observed by Voyager 1 (V1) in the heliosheath at the heliographic latitude approximately equal 34 deg as it moved away from the sun from 2005 through 2008.82. The pattern of the polarity of the magnetic field changed from alternating positive and negative polarities to predominantly negative polarities (magnetic fields pointing along the Archimedean spiral field angle toward the sun) at approximately equal 2006.23). This transition indicates that the latitudinal extent of the heliospheric current sheet (HCS) was decreasing in the supersonic solar wind, as expected for the declining phase of the solar cycle, and as predicted by extrapolation of the magnetic neutral line near the photosphere to the position of V1. However, the polarity was not uniformly negative in during 2008, in contrast to the predicted polarity. This difference suggests that the maximum latitudinal extent of the HCS was tending to increase in the northern hemisphere in the heliosheath, while it was decreasing in the supersonic solar wind. The large-scale magnetic field strength B(t) HCS was observed by V1 from 2005 through 2008.820. During this interval of decreasing solar activity toward solar minimum, B(t) at 1 AU was decreasing and the solar wind speed V at the latitude of V1 was increasing. Adjusting the temporal profile of B(t) observed by V1 for the solar cycle variations of B and V in the supersonic solar wind, we find that the radial gradient of B(R) in heliosheath from the radial distance R = 94.2 AU to 107.9 AU between 2005.0 and 2008.82 was 0.0017 nT/AU <= grad B <= 0.0055 nT/AU or grad B = (0.0036 +/- 0.0019) nT/AU

  5. Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

    Science.gov (United States)

    Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

    1996-01-01

    This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

  6. Signature of the solar cycle in the low degree p-modes using Mark-I

    CERN Document Server

    Jiménez-Reyes, S J; Pallé, P L; Jim\\'enez-Reyes, Sebasti\\'an J.; Corbard, Thierry; Pall\\'e, Pere L.

    2000-01-01

    High quality observations of the low degree p-modes exist for almost two complete solar cycles using the solar spectrophotometer Mark-I, located and operating at the Observatorio del Teide (Tenerife, Spain). In this work, the observations available have been re-analyzed over a much wider time interval than before. We analyze the time variation of the yearly frequency shift and its frequency dependence. This information will be used in order to average annual power spectra by removing the effect of the solar cycle. Using this average power spectrum, a new estimate of the rotational splittings is attempted.

  7. Observations of recurrent cosmic ray decreases during solar cycles 22 and 23

    Directory of Open Access Journals (Sweden)

    P. Dunzlaff

    2008-10-01

    Full Text Available During solar cycle 22, the modulation of several hundred MeV galactic cosmic rays (GCRs by recurrent and transient cosmic ray decreases was observed by the Ulysses spacecraft on its descent towards the solar south pole. In solar cycle 23, Ulysses repeated this trajectory segment during a similar phase of the solar cycle, but with opposite heliospheric magnetic field polarity. Since cosmic ray propagation in the heliosphere should depend on drift effects, we determine in this study the latitudinal distribution of the amplitude of recurrent cosmic ray decreases in solar cycles 22 and 23. As long as we measure the recurrent plasma structures in situ, we find that these decreases behave nearly the same in both cycles. Measurements in the fast solar wind, however, show differences: in cycle 22 (A>0 the recurrent cosmic ray decreases show a clear maximum near 25° and are still present beyond 40°, whereas we see in cycle 23 (A<0 neither such a pronounced maximum nor significant decreases above 40°. In other words: the periodicity in the cosmic ray intensity, which can be clearly seen in the slow solar wind, appears to vanish there. Theoretical models for drift effects, however, predict quite the opposite behaviour for the two solar cycles. To closer investigate this apparent contradiction, we first put the visual inspection of the data onto a more solid basis by performing a detailed Lomb (spectral analysis. The next step consists of an analysis of the resulting periodicities at 1 AU in order to distinguish between spatial and temporal variations, so that we can obtain statements about the question in how far there is a correlation between the in-situ data at 1 AU and those measured by Ulysses at larger latitudes. We find a good correlation being present during cycle 22, but not for cycle 23. As one potential explanation for this behaviour, we suggest the difference in the coronal hole structures between the cycles 22 and 23 due to a

  8. Performance comparison of different thermodynamic cycles for an innovative central receiver solar power plant

    Science.gov (United States)

    Reyes-Belmonte, Miguel A.; Sebastián, Andrés; González-Aguilar, José; Romero, Manuel

    2017-06-01

    The potential of using different thermodynamic cycles coupled to a solar tower central receiver that uses a novel heat transfer fluid is analyzed. The new fluid, named as DPS, is a dense suspension of solid particles aerated through a tubular receiver used to convert concentrated solar energy into thermal power. This novel fluid allows reaching high temperatures at the solar receiver what opens a wide range of possibilities for power cycle selection. This work has been focused into the assessment of power plant performance using conventional, but optimized cycles but also novel thermodynamic concepts. Cases studied are ranging from subcritical steam Rankine cycle; open regenerative Brayton air configurations at medium and high temperature; combined cycle; closed regenerative Brayton helium scheme and closed recompression supercritical carbon dioxide Brayton cycle. Power cycle diagrams and working conditions for design point are compared amongst the studied cases for a common reference thermal power of 57 MWth reaching the central cavity receiver. It has been found that Brayton air cycle working at high temperature or using supercritical carbon dioxide are the most promising solutions in terms of efficiency conversion for the power block of future generation by means of concentrated solar power plants.

  9. Comparing the solar magnetic field in the corona and in the inner heliosphere during solar cycles 21-23

    Science.gov (United States)

    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.

  10. Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies

    Science.gov (United States)

    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.

  11. Technology for Bayton-cycle powerplants using solar and nuclear energy

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Jaramillo, Andres; DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dasi-Espuig, Maria [Max-Planck-Institut fuer Sonnensystemforschung, D-37191 Katlenburg-Lindau (Germany); Balmaceda, Laura A., E-mail: amunoz@cfa.harvard.edu, E-mail: edeluca@cfa.harvard.edu, E-mail: dasi@mps.mpg.de, E-mail: lbalmaceda@icate-conicet.gob.ar [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina)

    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.

  13. Estimating the Size and Timing of the Maximum Amplitude of Solar Cycle 24

    Institute of Scientific and Technical Information of China (English)

    Ke-Jun Li; Peng-Xin Gao; Tong-Wei Su

    2005-01-01

    A simple statistical method is used to estimate the size and timing of maximum amplitude of the next solar cycle (cycle 24). Presuming cycle 23 to be a short cycle (as is more likely), the minimum of cycle 24 should occur about December 2006 (±2 months) and the maximum, around March 2011 (±9 months),and the amplitude is 189.9 ± 15.5, if it is a fast riser, or about 136, if it is a slow riser. If we presume cycle 23 to be a long cycle (as is less likely), the minimum of cycle 24 should occur about June 2008 (±2 months) and the maximum, about February 2013 (±8 months) and the maximum will be about 137 or 80, according as the cycle is a fast riser or a slow riser.

  14. Solar Cycle in the Heliosphere and Cosmic Rays

    Science.gov (United States)

    2014-10-23

    On the other hand, solar energetic particles can serve as probes for explosive phenomena on the Sun and conditions in the corona and inner...hot parts of the corona even in the absence of active sunspot regions. The likelihood that the solar wind was slow during the Maunder Minimum was...minima” and that “diffusion contributed ≈50 % of the total cosmic proton intensities observed at Earth while particle drifts contributed the other 50

  15. Parametric theoretical study of a two-stage solar organic Rankine cycle for RO desalination

    Energy Technology Data Exchange (ETDEWEB)

    Kosmadakis, G.; Manolakos, D.; Papadakis, G. [Department of Natural Resources and Agricultural Engineering, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens (Greece)

    2010-05-15

    The present work concerns the parametric study of an autonomous, two-stage solar organic Rankine cycle for RO desalination. The main goal of the current simulation is to estimate the efficiency, as well as to calculate the annual mechanical energy available for desalination in the considered cases, in order to evaluate the influence of various parameters on the performance of the system. The parametric study concerns the variation of different parameters, without changing actually the baseline case. The effect of the collectors' slope and the total number of evacuated tube collectors used, have been extensively examined. The total cost is also taken into consideration and is calculated for the different cases examined, along with the specific fresh water cost (EUR/m{sup 3}). (author)

  16. The study of Equatorial coronal hole during maximum phase of Solar Cycle 21, 22, 23 and 24

    Science.gov (United States)

    Karna, Mahendra; Karna, Nishu

    2017-08-01

    The 11-year Solar Cycle (SC) is characterized by the periodic change in the solar activity like sunspot numbers, coronal holes, active regions, eruptions such as flares and coronal mass ejections. We study the relationship between equatorial coronal holes (ECH) and the active regions (AR) as coronal whole positions and sizes change with the solar cycle. We made a detailed study of equatorial coronal hole for four solar maximum: Solar Cycle 21 (1979,1980,1981 and 1982), Solar Cycle 22 (1989, 1990, 1991 and 1992), Solar Cycle 23 (1999, 2000, 2001 and 2002) and Solar Cycle 24 (2012, 2013, 2014 and 2015). We used publically available NOAA solar coronal hole data for cycle 21 and 22. We measured the ECH region using the EIT and AIA synoptic map for cycle 23 and 24. We noted that in two complete 22-year cycle of solar activity, the equatorial coronal hole numbers in SC 22 is greater than SC 21 and similarly, SC 24 equatorial coronal hole numbers are greater than SC 23. Moreover, we also compared the position of AR and ECH during SC 23 and 24. We used daily Solar Region Summary (SRS) data from SWPC/NOAA website. Our goal is to examine the correlation between equatorial holes, active regions, and flares.

  17. Solar cycle length hypothesis appears to support the IPCC on global warming

    DEFF Research Database (Denmark)

    Laut, Peter; Gundermann, Jesper

    1999-01-01

    warming from the enhanced concentrations of greenhouse gases. The "solar hypothesis" 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 paper we have demonstrated that for data covering...... lengths with the "corrected" temperature anomalies is substantially better than with the historical anomalies. Therefore our findings support a total reversal of the common assumption that a verification of the solar hypothesis would challenge the IPCC assessment of man-made global warming.......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...

  18. Solar cycle length hypothesis appears to support the IPCC on global warming

    DEFF Research Database (Denmark)

    Laut, Peter; Gundermann, Jesper

    1999-01-01

    warming from the enhanced concentrations of greenhouse gases. The "solar hypothesis" 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 paper we have demonstrated that for data covering...... lengths with the "corrected" temperature anomalies is substantially better than with the historical anomalies. Therefore our findings support a total reversal of the common assumption that a verification of the solar hypothesis would challenge the IPCC assessment of man-made global warming.......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...

  19. Energy and exergy performance investigation of transcritical CO2-based Rankine cycle powered by solar energy

    Institute of Scientific and Technical Information of China (English)

    ZHANG XinRong; LI XiaoJuan

    2012-01-01

    A comprehensive performance evaluation of a solar assisted transcritical CO2-based Rankine cycle system is made with exergy analysis method.The actual thermal data taken from the all-day experiment of the system are utilized to determine energy transfer and the exergy destructions in each component of the system.In addition,a hypothetical carbon dioxide expansion turbine is introduced,then two thermodynamic models for solar transcritical carbon dioxide Rankine cycles with a throttling valve (experiment) and with an expansion turbine have been established with exergy analysis method.The obtained results clearly show that solar collector contributes the largest share to system irreversibility and entropy generation in the all-day working state,and the exergy improvement potential of solar collector is the maximum in the working state.So this component should be the optimization design focus to improve system exergy effectiveness.For the cycle with the turbine,the energy efficiency and the entropy generation are not much higher than the cycle with throttling valve,but the exergy efficiency of the cycle with turbine is twice of the cycle with throttling valve.It provides more guidance when the transcritical CO2-based Rankine system is in a large-scale solar application.

  20. Current collecting grids for ITO-free solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Galagan, Yulia; Gorter, Harrie; Sabik, Sami; Andriessen, Ronn [Holst Centre, High Tech Campus 31, Eindhoven (Netherlands); Zimmermann, Birger [Fraunhofer Institute for Solar Energy Systems ISE, Freiburg (Germany); Coenen, Erica W.C. [TNO Technical Sciences, Eindhoven (Netherlands); Joergensen, Mikkel; Krebs, Frederik C. [Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde (Denmark); Tanenbaum, David M. [Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde (Denmark); Department of Physics and Astronomy, Pomona College, Claremont, CA (United States); Slooff, Lenneke H.; Veenstra, Sjoerd C.; Kroon, Jan M. [Energy Research Centre of the Netherlands (ECN), Petten (Netherlands)

    2012-01-15

    Indium-tin-oxide (ITO) free polymer solar cells prepared by ink jet printing a composite front electrode comprising silver grid lines and a semitransparent PEDOT:PSS conductor are demonstrated. The effect of grid line density is explored for a large series of devices and a careful modeling study enabling the identification of the most rational grid structure is presented. Both optical and light beam induced current (LBIC) mapping of the devices are used to support the power loss model and to follow the evolution of the performance over time. Current generation is found to be evenly distributed over the active area initially progressing to a larger graduation in areas with different performance. Over time coating defects also become much more apparent in the LBIC images. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Return currents and energy transport in the solar flaring atmosphere

    CERN Document Server

    Codispoti, Anna; Piana, Michele; Pinamonti, Nicola

    2013-01-01

    According to a standard ohmic perspective, the injection of accelerated electrons into the flaring region violates local charge equilibrium and therefore, in response, return currents are driven by an electric field to equilibrate such charge violation. In this framework, the energy loss rate associated to these local currents has an ohmic nature and significantly shortens the acceleration electron path. In the present paper we adopt a different viewpoint and, specifically, we study the impact of the background drift velocity on the energy loss rate of accelerated electrons in solar flares. We first utilize the Rutherford cross-section to derive the formula of the energy loss rate when the collisional target has a finite temperature and the background instantaneously and coherently moves up to equilibrate the electron injection. We then use the continuity equation for electrons and imaging spectroscopy data provided by RHESSI to validate this model. Specifically, we show that this new formula for the energy l...

  2. Performance analysis of a solar-powered organic rankine cycle engine.

    Science.gov (United States)

    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%.

  3. Study of large Forbush decreases in cosmic-ray intensity observed during solar cycle 23 and 24

    Science.gov (United States)

    Kumar, Anand; Badruddin, B.

    2016-07-01

    Neutron monitors at different geomagnetic latitude and longitude of Earth measure the cosmic-ray intensity with high precision. Sudden decreases in cosmic-ray intensity within few hours and slow recovery to pre-decrease level within a few days (Forbush decreases) are observed in neutron monitor data. We identify large-amplitude Forbush decreases (FDs), using high counting rate neutron monitor data, that occurred during previous solar cycle 23 (1995-2009) and current solar cycle 24 (2010-2015). We then search for the solar sources and the interplanetary structures responsible for these decreases. We attempt to find the relative importance of various interplanetary plasma and field parameters and the physical mechanism(s) responsible for FDs of varying amplitudes. We analyze a number of interplanetary plasma and field parameters, during both the phases (main and recovery) of FDs. The interplanetary plasma and field data analyzed in this study are the solar-wind velocity, the interplanetary magnetic field, its fluctuations, interplanetary electric field and the time variation of interplanetary electric potential. For monitoring the changes in interplanetary plasma/field conditions during the development of FDs, we also utilize plasma density, temperature and plasma beta, dynamic pressure and Mach number during the passage of interplanetary structures responsible for FDs. In addition to their amplitude, we study the recovery of FDs in detail after determining the time constant during their recovery by exponential fit to the data. As the solar magnetic polarity reversed during the maximum phase of solar cycle 23 (in the year 2000), we study the differences in amplitude, time constant of recovery and plasma/field condition to search for the polarity dependent effects, if any, on the amplitude and recovery of FDs due to implication for the models suggested to explain the Forbush decrease phenomena. The implications of these results are discussed.

  4. Solar wind and substorm excitation of the wavy current sheet

    Science.gov (United States)

    Forsyth, C.; Lester, M.; Fear, R. C.; Lucek, E.; Dandouras, I.; Fazakerley, A. N.; Singer, H.; Yeoman, T. K.

    2009-06-01

    Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the -YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

  5. Solar wind and substorm excitation of the wavy current sheet

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2009-06-01

    Full Text Available Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002. We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005 and Erkaev et al. (2008. We find that the Erkaev et al. (2008 model gives the best fit to the observations.

  6. Changes in quasi-periodic variations of solar photospheric fields: precursor to the deep solar minimum in the cycle 23?

    CERN Document Server

    Bisoi, Susanta Kumar; Chakrabarty, D; Ananthakrishnan, S; Divekar, Ankur

    2013-01-01

    Using both wavelet and Fourier analysis, a study has been undertaken of the changes in the quasi-periodic variations in solar photospheric fields in the build-up to one of the deepest solar minima experienced in the past 100 years. This unusual and deep solar minimum occurred between solar cycles 23 and 24. The study, carried out using ground based synoptic magnetograms spanning the period 1975.14 to 2009.86, covered solar cycles 21, 22 and 23. A hemispheric asymmetry in periodicities of the photospheric fields was seen only at latitudes above $\\pm45{^{\\circ}}$ when the data was divided, based on a wavelet analysis, into two parts: one prior to 1996 and the other after 1996. Furthermore, the hemispheric asymmetry was observed to be confined to the latitude range 45${^{\\circ}}$ to 60${^{\\circ}}$. This can be attributed to the variations in polar surges that primarily depend on both the emergence of surface magnetic flux and varying solar surface flows. The observed asymmetry when coupled with the fact that bot...

  7. Long-term Variability in the Length of the Solar Cycle

    CERN Document Server

    Richards, Mercedes T; Richards, Donald St P

    2013-01-01

    The recent paucity of sunspots and the delay in the expected start of Solar Cycle 24 have drawn attention to the challenges involved in predicting solar activity. Traditional models of the solar cycle usually require information about the starting time and rise time as well as the shape and amplitude of the cycle. With this tutorial, we investigate the variations in the length of the sunspot number cycle and examine whether the variability can be explained in terms of a secular pattern. We identified long-term cycles in archival data from 1610 - 2000 using median trace analyses of the cycle length and power spectrum analyses of the (O-C) residuals of the dates of sunspot minima and maxima. Median trace analyses of data spanning 385 years indicate a cycle length with a period of 183 - 243 years, and a power spectrum analysis identifies a period of 188 $\\pm$ 38 years. We also find a correspondence between the times of historic minima and the length of the sunspot cycle, such that the cycle length increases duri...

  8. Spectral analysis of auroral geomagnetic activity during various solar cycles between 1960 and 2014

    Science.gov (United States)

    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.

  9. Cosmic rays, conditions in interplanetary space and geomagnetic variations during solar cycles 19-24

    Science.gov (United States)

    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.

  10. Interplanetary Lyman $\\alpha$ line profiles: variations with solar activity cycle

    CERN Document Server

    Quemerais, E; Bertaux, J L; Koutroumpa, D; Clarke, J; Kyrola, E; Schmidt, W; Qu\\'emerais, Eric; Lallement, Rosine; Bertaux, Jean-Loup; Koutroumpa, Dimitra; Clarke, John; Kyrola, Erkki; Schmidt, Walter

    2006-01-01

    Interplanetary Lyman alpha line profiles are derived from the SWAN H cell data measurements. The measurements cover a 6-year period from solar minimum (1996) to after the solar maximum of 2001. This allows us to study the variations of the line profiles with solar activity. These line profiles were used to derive line shifts and line widths in the interplanetary medium for various angles of the LOS with the interstellar flow direction. The SWAN data results were then compared to an interplanetary background upwind spectrum obtained by STIS/HST in March 2001. We find that the LOS upwind velocity associated with the mean line shift of the IP \\lya line varies from 25.7 km/s to 21.4 km/s from solar minimum to solar maximum. Most of this change is linked with variations in the radiation pressure. LOS kinetic temperatures derived from IP line widths do not vary monotonically with the upwind angle of the LOS. This is not compatible with calculations of IP line profiles based on hot model distributions of interplanet...

  11. Assessing the performance of thermospheric modelling with data assimilation throughout solar cycles 23 and 24

    CERN Document Server

    Murray, Sophie A; Jackson, David R; Bruinsma, Sean L

    2015-01-01

    Data assimilation procedures have been developed for thermospheric models using satellite density measurements as part of the EU Framework Package 7 ATMOP Project. Two models were studied; one a general circulation model, TIEGCM, and the other a semi-empirical drag temperature model, DTM. Results of runs using data assimilation with these models were compared with independent density observations from CHAMP and GRACE satellites throughout solar cycles 23 and 24. Time periods of 60 days were examined at solar minimum and maximum, including the 2003 Hallowe'en storms. The differences between the physical and the semi-empirical models have been characterised. Results indicate that both models tend to show similar behaviour; underestimating densities at solar maximum, and overestimating them at solar minimum. DTM performed better at solar minimum, with both models less accurate at solar maximum. A mean improvement of ~4% was found using data assimilation with TIEGCM. With further improvements, the use of general ...

  12. Rieger-type periodicity during solar cycles 14-24: estimation of dynamo magnetic field strength in the solar interior

    CERN Document Server

    Gurgenashvili, Eka; Kukhianidze, Vasil; Oliver, Ramon; Ballester, Jose Luis; Ramishvili, Giorgi; Shergelashvili, Bidzina; Hanslmeier, Arnold; Poedts, Stefaan

    2016-01-01

    Solar activity undergoes a variation over time scales of several months known as Rieger-type periodicity, which usually occurs near maxima of sunspot cycles. An early analysis showed that the periodicity appears only in some cycles, and is absent in other cycles. But the appearance/absence during different cycles has not been explained. We performed a wavelet analysis of sunspot data from the Greenwich Royal Observatory and the Royal Observatory of Belgium during cycles 14-24. We found that the Rieger-type periods occur in all cycles, but they are cycle-dependent: shorter periods occur during stronger cycles. Our analysis revealed a periodicity of 185-195 days during the weak cycles 14-15 and 24, and a periodicity of 155-165 days during the stronger cycles 16-23. We derived the dispersion relation of the spherical harmonics of the magnetic Rossby waves in the presence of differential rotation and a toroidal magnetic field in the dynamo layer near the base of the convection zone. This showed that the harmonic ...

  13. North-South Asymmetry in Rieger-type Periodicity during Solar Cycles 19-23

    Science.gov (United States)

    Gurgenashvili, Eka; Zaqarashvili, Teimuraz V.; Kukhianidze, Vasil; Oliver, Ramon; Ballester, Jose Luis; Dikpati, Mausumi; McIntosh, Scott W.

    2017-08-01

    Rieger-type periodicity has been detected in different activity indices over many solar cycles. It was recently shown that the periodicity correlates with solar activity having a shorter period during stronger cycles. Solar activity level is generally asymmetric between northern and southern hemispheres, which could suggest the presence of a similar behavior in the Rieger-type periodicity. We analyze the sunspot area/number and the total magnetic flux data for northern and southern hemispheres during solar cycles 19-23, which had remarkable north-south asymmetry. Using wavelet analysis of sunspot area and number during the north-dominated cycles (19-20), we obtained the periodicity of 160-165 days in the stronger northern hemisphere and 180-190 days in the weaker southern hemisphere. On the other hand, south-dominated cycles (21-23) display the periodicity of 155-160 days in the stronger southern hemisphere and 175-188 days in the weaker northern hemisphere. Therefore, the Rieger-type periodicity has the north-south asymmetry in sunspot area/number data during solar cycles with strong hemispheric asymmetry. We suggest that the periodicity is caused by magnetic Rossby waves in the internal dynamo layer. Using the dispersion relation of magnetic Rossby waves and observed Rieger periodicity, we estimated the magnetic field strength in the layer as 45-49 kG in more active hemispheres (north during cycles 19-20 and south during cycles 21-23) and 33-40 kG in weaker hemispheres. The estimated difference in the hemispheric field strength is around 10 kG, which provides a challenge for dynamo models. Total magnetic flux data during cycles 20-23 reveals no clear north-south asymmetry, which needs to be explained in the future.

  14. MAGNETIC FLUX CONSERVATION IN THE HELIOSHEATH INCLUDING SOLAR CYCLE VARIATIONS OF MAGNETIC FIELD INTENSITY

    Energy Technology Data Exchange (ETDEWEB)

    Michael, A. T.; Opher, M. [Astronomy Department, Boston University, Boston, MA 02115 (United States); Provornikova, E. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Richardson, J. D. [Kavli Center for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Tóth, G., E-mail: atmich@bu.edu, E-mail: mopher@bu.edu, E-mail: elena.a.provornikova@nasa.gov, E-mail: jdr@space.mit.edu, E-mail: gtoth@umich.edu [University of Michigan, Ann Arbor, MI 48109 (United States)

    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.

  15. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    Science.gov (United States)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

    2017-02-01

    Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1-800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibit multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.

  16. Neutral Air Density Variations Derived from Specular Meteor Echo Observation Spanning One Solar Cycle

    Science.gov (United States)

    Stober, G.; Matthias, V.; Chau, J. L.; Brown, P.

    2014-12-01

    Specular meteor radars (SMR) are a wide spread and established method to investigate mesospheric/ lower thermospheric (MLT) dynamics. Since 2002 the Canadian Meteor Orbit Radar (CMOR) conducts observations of meteor echoes in a fixed, stable configuration. Here we present measurements of the meteor peak flux altitude (MPFA) spanning one solar cycle at an altitude of 91 km. The MPFA is converted into neutral air density variations using a single body meteor ablation model and a NRLMSIS background atmosphere. We were able to separate the long term trend from the solar cycle effect assuming a linear trend and a sinusoidal solar cycle effect. The neutral air density shows a solar cycle signature of 2.4 +/-0.7% for solar cycle 23/24. The long term trend indicates a decreasing neutral air density of 5.8+/-1.1% per decade, which is in reasonable agreement to the model results of Akmaev et al., 2006. They predicted a decrease of neutral air density for the MLT in the order of 5-6% per decade due to greenhouse gas cooling.

  17. Revisiting the prediction of solar activity based on the relationship between the solar maximum amplitude and max-max cycle length

    CERN Document Server

    Carrasco, V M S; Gallego, M C

    2016-01-01

    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.

  18. Assessment of the environmental impacts deriving from the life cycle of a typical solar water heater

    Directory of Open Access Journals (Sweden)

    G. Gaidajis

    2014-01-01

    Full Text Available According to life cycle thinking, the environmental burden deriving from different life cycle stages of a product or a system, such as manufacturing, transportation, maintenance and landfilling should be taken into consideration while assessing its environmental performance. In that aspect, the environmental impacts deriving from the life cycle of a typical solar water heater (SWH in Greece are analyzed and assessed with the application of relative life cycle assessment (LCA software in this study. In order to examine various impact categories such as global warming, ozone layer depletion, ecotoxicity and so forth, the IMPACT2002+ method is applied. The aim of this study is to examine the life cycle stages, processes and materials that significantly affect the system under examination and to provide a discussion regarding the environmental friendliness of solar water heaters.

  19. Experimental and Thermoeconomic Analysis of Small-Scale Solar Organic Rankine Cycle (SORC System

    Directory of Open Access Journals (Sweden)

    Suresh Baral

    2015-04-01

    Full Text Available A small-scale solar organic Rankine cycle (ORC is a promising renewable energy-driven power generation technology that can be used in the rural areas of developing countries. A prototype was developed and tested for its performance characteristics under a range of solar source temperatures. The solar ORC system power output was calculated based on the thermal and solar collector efficiency. The maximum solar power output was observed in April. The solar ORC unit power output ranged from 0.4 kW to 1.38 kW during the year. The highest power output was obtained when the expander inlet pressure was 13 bar and the solar source temperature was 120 °C. The area of the collector for the investigation was calculated based on the meteorological conditions of Busan City (South Korea. In the second part, economic and thermoeconomic analyses were carried out to determine the cost of energy per kWh from the solar ORC. The selling price of electricity generation was found to be $0.68/kWh and $0.39/kWh for the prototype and low cost solar ORC, respectively. The sensitivity analysis was carried out in order to find the influencing economic parameters for the change in NPV. Finally, the sustainability index was calculated to assess the sustainable development of the solar ORC system.

  20. Next Generation UV Coronagraph Instrumentation for Solar Cycle-24

    Indian Academy of Sciences (India)

    John L. Kohl; Rajmal Jain; Steven R. Cranmer; Larry D. Gardner; Anil K. Pradhan; John C. Raymond; Leonard Strachan

    2008-03-01

    Ultraviolet coronagraph observations of the extended solar corona (defined here as 1.5 to 10 solar radii from Sun-center) have become a powerful tool for obtaining detailed empirical descriptions of coronal holes, streamers, and coronal mass ejections. The empirical models resulting from ultraviolet coronagraph observations provide the constraints needed to test and guide theoretical models aimed at determining the physical processes that control solar wind acceleration, CME heating and acceleration, and solar energetic particle (SEP) acceleration. Measurements to date from sounding rockets, the shuttle deployed Spartan 201 satellite and the Solar and Heliospheric Observatory (SOHO) have utilized high resolution spectroscopy over a very limited instantaneous field of view. New concepts for next generation instrumentation include imaging ultraviolet spectrocoronagraphs and large aperture ultraviolet coronagraph spectrometers. An imaging instrument would be the first to obtain absolute spectral line intensities of the extended corona over a wide field of view. Such images would provide the absolute intensities of spectral lines that can be used to determine densities and outflow velocities of specific coronal ions. Measurements from several charge states of a given element will allow electron temperatures to be determined. These measurements combined with observations of H I Ly provide absolute chemical abundances (relative to hydrogen) for observed elements. Ultraviolet imaging would be highly complementary to a large-aperture ultraviolet coronagraph spectrometer designed for high spectral resolution observations over a small instantaneous field of view. The images would be used to select targets for more detailed spectroscopic studies with the large aperture UV coronagraph spectrometer and to provide time dependent empirical descriptions of the regions surrounding the narrow instantaneous field of view of the large aperture instrument. Descriptions of both the

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

    CERN Document Server

    Jang, Minhwan; Hong, Sunhak; Choe, G S

    2016-01-01

    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 areas and the statistics of splitting and merging events of coronal holes and coronal mass ejections detected by SOHO/LASCO C3 in solar cycle 23. Although the total coronal hole area is at its maximum near the sunspot minimum, in which polar coronal holes prevail, it shows a comparable second maximum in the declining phase of the cycle, in which low latitude coronal holes are dominant. The events of coronal hole 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 coronal mass ejections are also over-populated in the declining phase of the cycle. From these results ...

  2. Improving Cycling Performance: Transcranial Direct Current Stimulation Increases Time to Exhaustion in Cycling.

    Directory of Open Access Journals (Sweden)

    Marcelo Vitor-Costa

    Full Text Available The central nervous system seems to have an important role in fatigue and exercise tolerance. Novel noninvasive techniques of neuromodulation can provide insights on the relationship between brain function and exercise performance. The purpose of this study was to determine the effects of transcranial direct current stimulation (tDCS on physical performance and physiological and perceptual variables with regard to fatigue and exercise tolerance. Eleven physically active subjects participated in an incremental test on a cycle simulator to define peak power output. During 3 visits, the subjects experienced 3 stimulation conditions (anodal, cathodal, or sham tDCS-with an interval of at least 48 h between conditions in a randomized, counterbalanced order to measure the effects of tDCS on time to exhaustion at 80% of peak power. Stimulation was administered before each test over 13 min at a current intensity of 2.0 mA. In each session, the Brunel Mood State questionnaire was given twice: after stimulation and after the time-to-exhaustion test. Further, during the tests, the electromyographic activity of the vastus lateralis and rectus femoris muscles, perceived exertion, and heart rate were recorded. RM-ANOVA showed that the subjects performed better during anodal primary motor cortex stimulation (491 ± 100 s compared with cathodal stimulation (443 ± 11 s and sham (407 ± 69 s. No significant difference was observed between the cathodal and sham conditions. The effect sizes confirmed the greater effect of anodal M1 tDCS (anodal x cathodal = 0.47; anodal x sham = 0.77; and cathodal x sham = 0.29. Magnitude-based inference suggested the anodal condition to be positive versus the cathodal and sham conditions. There were no differences among the three stimulation conditions in RPE (p = 0.07 or heart rate (p = 0.73. However, as hypothesized, RM- ANOVA revealed a main effect of time for the two variables (RPE and HR: p < 0.001. EMG activity also did not

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

    Energy Technology Data Exchange (ETDEWEB)

    Egeland, Ricky [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Metcalfe, Travis S. [Space Science Institute, 4750 Walnut St. Suite 205, Boulder, CO 80301 (United States); Hall, Jeffrey C. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Henry, Gregory W., E-mail: egeland@ucar.edu [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209 (United States)

    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.

  4. Glacial cycles and solar insolation: the role of orbital, seasonal, and spatial variations

    Science.gov (United States)

    Kaufmann, R. K.; Juselius, K.

    2010-11-01

    We use a statistical model, the cointegrated vector autoregressive model, to evaluate the relative roles that orbital, seasonal, and spatial variations in solar insolation play in glacial cycles during the late Quaternary (390kyr - present). To do so, we estimate models of varying complexity and compare the accuracy of their in-sample simulations. Results indicate that variations in solar insolation associated with changes in Earth's orbit have the greatest explanatory power and that obliquity, precession, and eccentricity are needed to generate an accurate simulation of glacial cycles. Seasonal variations in insolation play a lesser role, while cumulative summer-time insolation has little explanatory power. Finally, solar insolation in the Northern Hemisphere generates the more accurate in-sample simulation of surface temperature while ice volume is simulated most accurately by solar insolation in the Southern Hemisphere.

  5. Equatorial thermospheric wind changes during the solar cycle - Measurements at Arequipa, Peru, from 1983 to 1990

    Science.gov (United States)

    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).

  6. Interdigitated back contact solar cell with high-current collection

    Energy Technology Data Exchange (ETDEWEB)

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    1981-01-01

    Internal current-collection efficiencies greater than 90 percent and energy-conversion efficiencies of 18 percent at 30 suns have been measured on a laboratory version of the interdigitated back contact (IBC) solar cell. The quantum efficiency at 600 nm was greater than 90 percent which implies a minority carrier lifetime of greater than 350 ..mu..sec and a front surface recombination velocity of less than 30 cm/sec on the better devices. To achieve these high-current collection efficiencies, a phosphorous gettering diffusion was performed on the front surface and then etched off. Also, thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. This should result in higher efficiencies at high concentration.

  7. Using the Dipolar and Quadrupolar Moments to Improve Solar-Cycle Predictions Based on the Polar Magnetic Fields

    CERN Document Server

    Muñoz-Jaramillo, Andrés; DeLuca, Edward E

    2013-01-01

    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 and climate). In recent years there has been an effort to develop accurate solar cycle predictions, leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. Here we show that cycle predictions can be made more accurate if performed separately for each hemisphere, taking advantage of information about both the dipolar and quadrupolar moments of the solar magnetic field during minimum.

  8. Measurements of sunspot group tilt angles for solar cycles 19-24

    Science.gov (United States)

    Isik, Seda; Isik, Emre

    2016-07-01

    The tilt angle of a sunspot group is a critical quantity in the surface transport magnetic flux on global scales, playing a role in the solar dynamo. To investigate Joy's law for four cycles, we measured the tilt angles of sunspot groups for solar cycles 19-24. We have developed an IDL routine, which allows the user to interactively select and measure sunspot positions and areas on the solar disc, using the sunspot drawing database of Kandilli Observatory. The method is similar to that used by others in the literature, with the exception that sunspot groups were identified manually, which has improved the accuracy of the tilt angles. We present cycle averages of the tilt angle and compare the results with the existing data in the literature.

  9. Optimal design of compact organic Rankine cycle units for domestic solar applications

    DEFF Research Database (Denmark)

    Barbazza, Luca; Pierobon, Leonardo; Mirandola, Alberto

    2014-01-01

    Organic Rankine cycle turbogenerators are a promising technology to transform the solar radiation harvested by solar collectors into electric power. The present work aims at sizing a small-scale organic Rankine cycle unit by tailoring its design for domestic solar applications. Stringent design...... criteria, i.e., compactness, high performance and safe operation, are targeted by adopting a multi-objective optimization approach modeled with the genetic algorithm. Design-point thermodynamic variables, e.g., evaporating pressure, the working fluid, minimum allowable temperature differences....... Findings also suggest that the evaporator and condenser minimum allowable temperature differences have the largest impact on the system volume and on the cycle performances. Among the fluids considered, the results indicate that R1234yf and R1234ze are the best working fluid candidates. Using flat plate...

  10. Energy Storage and Release through the Solar Activity Cycle Models Meet Radio Observations

    CERN Document Server

    Nindos, Alexander

    2012-01-01

    For nearly sixty years, radio observations have provided a unique insight into the physics of the active and quiescent solar atmosphere. Thanks to the variety of emission mechanisms and to the large altitude range available to observations, fundamental plasma parameters have been measured from the low chromosphere to the upper corona and interplanetary medium. This book presents current research in solar radio astronomy and shows how well it fits in the exceptional scientific context brought by the current space solar observatories. It essentially contains contributed research and review papers presented during the 2010 Community of European Solar Radio Astronomers (CESRA) meeting, which took place in Belgium in June 2010. This book is aimed at graduate students and researchers working in solar physics and space science. Previously published in Solar Physics journal, Vol. 273/2, 2011.

  11. Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks

    OpenAIRE

    Zepp, R. G.; D. J. Erickson; Paul, N.D.; Sulzberger, B.

    2011-01-01

    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 of these effects with climate change, including feedbacks on climate. Such interactions occur in both terrestrial and aquatic ecosystems. While there is significant uncertainty in the quantification of these effects,...

  12. A 3NM-64_3He added to LARC for Solar Extreme Event studies during solar cycle 24

    Science.gov (United States)

    Storini, M.; Signoretti, F.; Diego, P.; Re, F.; Laurenza, M.

    2009-02-01

    The Antarctic Laboratory for Cosmic Rays (LARC, acronym for Laboratorio Antartico per i Raggi Cosmici or Laboratorio Antártico para Rayos Cósmicos) operates on King George Island (South Shetlands). Since January 1991 a standard 6NM-64 detector has been recording continuous cosmic ray measurements and several Ground-Level Enhancements have been registered. Here we describe the different phases performed in Italy for the realization of a 3NM-64_3He detector, which started its measurements during the Italian XXII Antarctic Summer Campaign. Data recorded during solar activity cycle 24 will furnish an useful research tool for the next Solar Extreme Events.

  13. Health physics and aviation: solar cycle 23 (1996-2008).

    Science.gov (United States)

    Barish, R J

    2009-04-01

    We continue our description of the scientific and professional activities that were initiated by the classification of airline flight crewmembers as occupational radiation workers in 1994, specifically looking at the period between 1996 and 2008. During this period, radiation measurement programs were conducted on numerous commercial aircraft flights. Epidemiological studies have looked at the incidence of cancer in pilots and flight attendants, with mixed conclusions. The Federal Aviation Administration (FAA) released revised versions of its CARI software, the computer program designed to evaluate radiation exposures received on user-defined flight plans. Additional dose-evaluation programs have been made available by other entities. In May 2000, member states of the European Union (EU) adopted regulations that apply to the air carriers in all twenty-seven nations requiring education on health risks of in-flight radiation as well as dose assessment for all EU flight crewmembers. The National Oceanic and Atmospheric Administration (NOAA) revised its classification scheme for space weather events including radiation-producing solar storms. In 2005, the FAA created a Solar Particle Alert system to warn aircraft of high radiation levels caused by significant events of this type. There is now an early-warning system for potentially harmful solar particle events. This new system depends on the earlier arrival time of relativistic electrons compared with the heavier particulate radiation.

  14. Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

    Science.gov (United States)

    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.

  15. Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies

    CERN Document Server

    Muñoz-Jaramillo, Andrés; Balmaceda, Laura A; DeLuca, Edward E; 10.1088/2041-8205/767/2/L25

    2013-01-01

    The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and the 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 vs.\\ 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 uncor...

  16. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    Science.gov (United States)

    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...

  17. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    Science.gov (United States)

    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...

  18. Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

    OpenAIRE

    Rahul Bhosale; Anand Kumar; Fares AlMomani; Ujjal Ghosh; Mohammad Saad Anis; Konstantinos Kakosimos; Rajesh Shende; Marc A. Rosen

    2016-01-01

    The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar) step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and wat...

  19. Solution and vapour deposited lead perovskite solar cells: Ecotoxicity from a life cycle assessment perspective

    DEFF Research Database (Denmark)

    Espinosa Martinez, Nieves; Serrano-Luján, Lucía; Urbina, Antonio

    2015-01-01

    the inventory for all the components employed for the two different device architectures that resemble respectively a traditional dye sensitised solar cell (DSSC) and an inverted polymer solar cell (OPV). We analyse the impacts from generation of 1 kWh of electricity and assume a lifetime of 1 year......We present a life cycle analysis (LCA) and an environmental impact analysis (EIA) of lead based perovskite solar cells prepared according to the two most successfully reported literature methods that comprise either vapour phase deposition or solution phase deposition. We have developed...... lead(II)halides is very limited compared to methylammoniumhalides employed. This applies during the raw materials extraction, synthesis of the starting materials and manufacture of the perovskite solar cells and from these points of view the lead based perovskite solar cells do not pose extra concerns...

  20. A Note on Solar Cycle Length during the Medieval Climate Anomaly

    CERN Document Server

    Vaquero, J M

    2012-01-01

    The growing interest in the "Medieval Climate Anomaly" (MCA) and its possible link to anomalous solar activity has prompted new reconstructions of solar activity based on cosmogenic radionuclides. These proxies however do not sufficiently constrain the Total Solar Irradiance (TSI) range, and are often defined at low temporal resolution, inadequate to infer the solar cycle length (SCL). We have reconstructed the SCL (average duration of 10.72 \\pm 0.20 years) during the MCA using observations of naked-eye sunspot and aurora sightings. Thus, solar activity was most probably not exceptionally intense, supporting the view that internal variability of the coupled ocean-atmosphere system was the main driver of MCA.

  1. Life-Cycle Assessment of Solar Charger with Integrated Organic Photovoltaics

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Espinosa Martinez, Nieves; Krebs, Frederik C

    2017-01-01

    OPV panel, enabling the possibility to be charged from the sun, and not only from the grid. In this paper, two well-established power bank products using amorphous silicon solar panels (a-Si PV) and a regular power bank without any portable solar panel is compared to HeLi-on. The environmental impact...... of the products is quantified with the aim of indicate where eco-design improvements would make a difference and to point out performance of a portable solar panel depending on the context of use (Denmark and China), realistic disposal scenarios and the recycling relevance particularly concerning metals content.......Organic photovoltaics (OPV) applied in a commercial product comprising a solar charged power bank is subjected to a life cycle assessment (LCA) study. Regular power banks harvest electricity from the grid only. The solar power bank (called HeLi-on) is however, a power bank that includes a portable...

  2. Dynamics of the photosphere along the solar cycle from SDO/HMI

    Science.gov (United States)

    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.

  3. Life Cycle Assessment of Titania Perovskite Solar Cell Technology for Sustainable Design and Manufacturing.

    Science.gov (United States)

    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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. DOES THE VARIATION OF THE SOLAR INTRA-NETWORK HORIZONTAL FIELD FOLLOW THE SUNSPOT CYCLE?

    Energy Technology Data Exchange (ETDEWEB)

    Jin, C. L.; Wang, J. X., E-mail: cljin@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-07-01

    The ubiquitousness of the solar inter-network horizontal magnetic field has been revealed by space-borne observations with high spatial resolution and polarization sensitivity. However, no consensus has been achieved on the origin of the horizontal field among solar physicists. For a better understanding, in this study, we analyze the cyclic variation of the inter-network horizontal field by using the spectro-polarimeter observations provided by the Solar Optical Telescope on board Hinode, covering the interval from 2008 April to 2015 February. The method of wavelength integration is adopted to achieve a high signal-to-noise ratio. It is found that from 2008 to 2015 the inter-network horizontal field does not vary when solar activity increases, and the average flux density of the inter-network horizontal field is 87 ± 1 G, In addition, the imbalance between horizontal and vertical fields also keeps invariant within the scope of deviation, i.e., 8.7 ± 0.5, from the solar minimum to maximum of solar cycle 24. This result confirms that the inter-network horizontal field is independent of the sunspot cycle. The revelation favors the idea that a local dynamo is creating and maintaining the solar inter-network horizontal field.

  5. Interglacials, Milankovitch Cycles, Solar Activity, and Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Gerald E. Marsh

    2014-01-01

    Full Text Available The existing understanding of interglacial periods is that they are initiated by Milankovitch cycles enhanced by rising atmospheric carbon dioxide concentrations. During interglacials, global temperature is also believed to be primarily controlled by carbon dioxide concentrations, modulated by internal processes such as the Pacific Decadal Oscillation and the North Atlantic Oscillation. Recent work challenges the fundamental basis of these conceptions.

  6. Interglacials, Milankovitch Cycles, Solar Activity, and Carbon Dioxide

    OpenAIRE

    Marsh, Gerald E.

    2014-01-01

    The existing understanding of interglacial periods is that they are initiated by Milankovitch cycles enhanced by rising atmospheric carbon dioxide concentrations. During interglacials, global temperature is also believed to be primarily controlled by carbon dioxide concentrations, modulated by internal processes such as the Pacific Decadal Oscillation and the North Atlantic Oscillation. Recent work challenges the fundamental basis of these conceptions.

  7. Life cycle assessment Part 2 : Current impact assessment practice

    NARCIS (Netherlands)

    Pennington, DW; Potting, J; Finnveden, G; Lindeijer, E; Jolliet, O; Rydberg, T; Rebitzer, G

    2004-01-01

    Providing our society with goods and services contributes to a wide range of environmental impacts. Waste generation, emissions and the consumption of resources occur at many stages in a product's life cycle-from raw material extraction, energy acquisition, production and manufacturing, use, reuse,

  8. Life cycle assessment Part 2 : Current impact assessment practice

    NARCIS (Netherlands)

    Pennington, DW; Potting, J; Finnveden, G; Lindeijer, E; Jolliet, O; Rydberg, T; Rebitzer, G

    2004-01-01

    Providing our society with goods and services contributes to a wide range of environmental impacts. Waste generation, emissions and the consumption of resources occur at many stages in a product's life cycle-from raw material extraction, energy acquisition, production and manufacturing, use, reuse,

  9. Life cycle assessment Part 2 : Current impact assessment practice

    NARCIS (Netherlands)

    Pennington, D.W; Potting, J; Finnveden, G; Lindeijer, E; Jolliet, O; Rydberg, T.; Rebitzer, G.

    Providing our society with goods and services contributes to a wide range of environmental impacts. Waste generation, emissions and the consumption of resources occur at many stages in a product's life cycle-from raw material extraction, energy acquisition, production and manufacturing, use, reuse,

  10. Satellite observations of an annual cycle in the Agulhas Current

    CSIR Research Space (South Africa)

    Krug, Marjolaine, J

    2012-08-01

    Full Text Available years of along-track altimetry and merged altimetry and close to 7 years of high frequency Sea Surface Temperature (SST) observations. While the position and width of the Agulhas Current’s dynamical core do not display an annual cycle, the geostrophic...

  11. Climatology of rapid geomagnetic variations at high latitudes over two solar cycles

    Directory of Open Access Journals (Sweden)

    A. Viljanen

    2011-10-01

    Full Text Available We investigate the characteristics of rapid geomagnetic variations at high latitudes based on the occurrence of large time derivatives of the horizontal magnetic field (dH/dt exceeding 1 nT s−1. Analysis of IMAGE magnetometer data from North Europe in 1983–2010, covering more than two solar cycles, confirms and specifies several previous findings. We show that dH/dt activity is high around the midnight and early morning hours, and nearly vanishes at noon and early afternoon. This happens during all seasons, although the midnight maximum is nearly invisible during summer. As indicated by modelled ionospheric equivalent currents, large dH/dt values occur predominantly during westward ionospheric electrojets. Before and around midnight, dH/dt tends to be north-south oriented, whereas in the morning hours, its direction is more west-east directed. dH/dt tends to be more strictly north-south oriented during winter than other seasons. The seasonal occurrence of large dH/dt values is similar to the variation of the maximum amplitude of westward equivalent currents. The yearly fraction of east-west directed large dH/dt vectors at the Kilpisjärvi station (MLAT 65.88 varies from 31 to 47 % without any clear correlation with the general geomagnetic activity nor with the yearly averages of solar wind parameters.

  12. The new climate data record of total and spectral solar irradiance: Current progress and future steps

    Science.gov (United States)

    Coddington, Odele; Lean, Judith; Rottman, Gary; Pilewskie, Peter; Snow, Martin; Lindholm, Doug

    2016-04-01

    We present a climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), with associated time and wavelength dependent uncertainties, from 1610 to the present. The data record was developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder and the Naval Research Laboratory (NRL) as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program, where the data record, source code, and supporting documentation are archived. TSI and SSI are constructed from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk using linear regression of proxies of solar magnetic activity with observations from the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor (TIM), Spectral Irradiance Monitor (SIM), and SOlar Stellar Irradiance Comparison Experiment (SOLSTICE). We show that TSI can be separately modeled to within TIM's measurement accuracy from solar rotational to solar cycle time scales and we assume that SSI measurements are reliable on solar rotational time scales. We discuss the model formulation, uncertainty estimates, and operational implementation and present comparisons of the modeled TSI and SSI with the measurement record and with other solar irradiance models. We also discuss ongoing work to assess the sensitivity of the modeled irradiances to model assumptions, namely, the scaling of solar variability from rotational-to-cycle time scales and the representation of the sunspot darkening index.

  13. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  14. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  15. On HMI solar oblateness during solar cycle 24 and impact of the space environment on results

    Science.gov (United States)

    Meftah, M.; Hauchecorne, A.; Bush, R. I.; Irbah, A.

    2016-10-01

    Solar oblateness is a fundamental parameter of the Sun, which provides indirect information on the inner rotation profile and on the distribution of matter. It also puts constraints on General Relativity. But this quantity is difficult to measure due to its very small value where the solar equator-to-pole radius difference is less than 10 milli-arcsecond (mas). Indeed, the measurements can be affected by magnetic activity and by instrumental effects linked to the space environment. The Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO) has produced accurate determinations of the solar oblateness from 2010 to 2015. The HMI measurements of the solar shape are obtained during special roll maneuvers of the spacecraft by 11.25 degrees steps around the spacecraft to the Sun line. HMI roll maneuver has been repeated ten times after the commissioning phase from October 2010 to July 2015. From HMI data, we observed a slight anti-correlation between solar oblateness and solar activity. From a new correction method, we found a mean solar equator-to-pole radius difference of 8.36 ± 0.49 mas (i.e. 6.06 ± 0.35 km at one σ) at 617.3 nm during the period 2010-2015.

  16. Solar Cycle Effects on the Near-Earth Space Systems

    Science.gov (United States)

    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. Efficient thermal cycling of solar panels in solar simulation facilities with a multi-panel test rig

    Science.gov (United States)

    Brinkmann, P. W.; Reimann, J.

    1980-06-01

    It is shown that efficient thermal cycling tests under vacuum can be performed at reduced costs to cover the requirements for qualifications and acceptance testing of solar panels. A suitable test rig was developed which allows simultaneous testing of up to 3 solar panels with a dimension of 1.3 m x 1.7 m each. The tests can be performed in an existing solar simulation facility with a beam diameter of only 2.4 m. This means that a close simulation of orbital conditions can be achieved, including severe eclipse conditions with rapid temperature changes. Chamber dimensions, descriptions of suspension devices, and other data needed by potential users are given.

  18. SOLAR MAGNETIC ACTIVITY CYCLES, CORONAL POTENTIAL FIELD MODELS AND ERUPTION RATES

    Energy Technology Data Exchange (ETDEWEB)

    Petrie, G. J. D. [National Solar Observatory, Tucson, AZ 85719 (United States)

    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.

  19. The Influence of the Solar Cycle on Plasmasphere Refilling

    Science.gov (United States)

    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.

  20. Shared Solar. Current Landscape, Market Potential, and the Impact of Federal Securities Regulation

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Brockway, Anna M. [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Ulrich, Elaine [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-04-01

    This report provides a high-level overview of the current U.S. shared solar landscape and the impact that a given shared solar program’s structure has on requiring federal securities oversight, as well as an estimate of market potential for U.S. shared solar deployment.

  1. Shared Solar. Current Landscape, Market Potential, and the Impact of Federal Securities Regulation

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, David [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Brockway, Anna M. [U.S. Department of Energy, Washington, DC (United States); Ulrich, Elaine [U.S. Department of Energy, Washington, DC (United States); Margolis, Robert [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-04-07

    This report provides a high-level overview of the current U.S. shared solar landscape, the impact that a given shared solar program’s structure has on requiring federal securities oversight, as well as an estimate of market potential for U.S. shared solar deployment.

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

    Science.gov (United States)

    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

  3. Sun-Like Magnetic Cycles in the Rapidly-Rotating Young Solar Analog HD 30495

    CERN Document Server

    Egeland, Ricky; Hall, Jeffrey C; Henry, Gregory W

    2015-01-01

    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 ($\\sim$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, an $\\sim$1 Gyr-old G1.5V 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 $\\sim$1.7 years and a long cycle of $...

  4. Comparison of Total Solar Irradiance with NASA/NSO Spectromagnetograph Data in Solar Cycles 22 and 23

    Science.gov (United States)

    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.

  5. Smaller Forbush Decreases in Solar Cycle 24: Effect of the Weak CME Field Strength?

    Science.gov (United States)

    Thakur, N.

    2015-12-01

    A Forbush decrease (FD) is a sudden depression in the intensity of galactic cosmic ray (GCR) background, followed by a gradual recovery. One of the major causes of FDs is the presence of magnetic structures such as magnetic clouds (MCs) or corotating interaction regions (CIRs) that have enhanced magnetic field, which can scatter particles away reducing the observed GCR intensity. Recent work (Gopalswamy et al. 2014, GRL 41, 2673) suggests that coronal mass ejections (CMEs) are expanding anomalously in solar cycle 24 due to the reduced total pressure in the ambient medium. One of the consequences of the anomalous expansion is the reduced magnetic content of MCs, so we expect subdued FDs in cycle 24. In this paper, we present preliminary results from a survey of FDs during MC events in cycle 24 in comparison with those in cycle 23. We find that only ~17% FDs in cycle 24 had an amplitude >3%, as compared to ~31% in cycle 23. This result is consistent with the difference in the maximum magnetic field intensities (Bmax) of MCs in the two cycles: only ~ 10% of MCs in cycle 24 have Bmax>20nT, compared to 22% in cycle 23, confirming that MCs of cycle 24 have weaker magnetic field content. Therefore, we suggest that weaker magnetic field intensity in the magnetic clouds of cycle 24 has led to FDs with smaller amplitudes.

  6. Synchronized Northern Hemisphere climate change and solar magnetic cycles during the Maunder Minimum.

    Science.gov (United States)

    Yamaguchi, Yasuhiko T; Yokoyama, Yusuke; Miyahara, Hiroko; Sho, Kenjiro; Nakatsuka, Takeshi

    2010-11-30

    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 (δ(18)O) 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; Δ(14)C) and climate (δ(18)O) isotope records derived from annual tree rings. The tree-ring δ(18)O record in Japan shows distinct negative δ(18)O 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 δ(18)O record and the GCR flux reconstructed by an ice-core (10)Be 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.

  7. Chaos and periodicity in solar wind speed: cycle 23

    Science.gov (United States)

    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.

  8. CME-flare association during the 23rd solar cycle

    Science.gov (United States)

    Mahrous, A.; Shaltout, M.; Beheary, M. M.; Mawad, R.; Youssef, M.

    2009-04-01

    The relation between coronal mass ejections (CMEs) and solar flares are statistically studied. More than 10,000 CME events observed by SOHO/LASCO during the period 1996-2005 have been analyzed. The soft X-ray flux measurements provided by the Geostationary Operational Environmental Satellite (GOES), recorded more than 20,000 flares in the same time period. The data is filtered under certain temporal and spatial conditions to select the CME-flare associated events. The results show that CME-flare associated events are triggered with a lift-off time within the range 0.4-1.0 h. We list a set of 41 CME-flare associated events satisfying the temporal and spatial conditions. The listed events show a good correlation between the CME energy and the X-ray flux of the CME-flare associated events with correlation coefficient of 0.76.

  9. The CME - Flare Relationship During The Present Solar Cycle

    Science.gov (United States)

    Shaltout, M.; Mahrous, A.; Youssef, M.; Mawad, R.; El-Naway, M.

    The relation between the Coronal mass Ejection CME and the solar flare is statistically studied More than ten thousand CME events observed by SOHO LASCO during the period 1996-2005 have been analyzed The soft x-ray flux measurements provided by the Geostationary Operational Environmental Satellite GEOS recorded more than twenty thousand flares in the same time period The data have been filtered under certain temporal and spatial conditions to select the CME-flare associated events The results show that the lift-off time of CME-flare associated events having a time interval within the range 0 4 sim 0 6 hour after the occurrence time of associated flares The CME events have been classified into a certain categories according to its energy E CME and the classes of the associated flares In addition we found a good linear correlation between the E CME and the x-ray flux of associated flare events

  10. Solar cycle variations of stratospheric ozone and temperature in simulations of a coupled chemistry-climate model

    Directory of Open Access Journals (Sweden)

    J. Austin

    2007-01-01

    Full Text Available The results from three 45-year simulations of a coupled chemistry climate model are analysed for solar cycle influences on ozone and temperature. The simulations include UV forcing at the top of the atmosphere, which includes a generic 27-day solar rotation effect as well as the observed monthly values of the solar fluxes. The results are analysed for the 27-day and 11-year cycles in temperature and ozone. In accordance with previous results, the 27-day cycle results are in good qualitative agreement with observations, particularly for ozone. However, the results show significant variations, typically a factor of two or more in sensitivity to solar flux, depending on the solar cycle. In the lower and middle stratosphere we show good agreement also between the modelled and observed 11-year cycle results for the ozone vertical profile averaged over low latitudes. In particular, the minimum in solar response near 20 hPa is well simulated. In comparison, experiments of the model with fixed solar phase (solar maximum/solar mean and climatological sea surface temperatures lead to a poorer simulation of the solar response in the ozone vertical profile, indicating the need for variable phase simulations in solar sensitivity experiments. The role of sea surface temperatures and tropical upwelling in simulating the ozone minimum response are also discussed.

  11. Solar cycle variations of stratospheric ozone and temperature in simulations of a coupled chemistry-climate model

    Science.gov (United States)

    Austin, J.; Hood, L. L.; Soukharev, B. E.

    2007-03-01

    The results from three 45-year simulations of a coupled chemistry climate model are analysed for solar cycle influences on ozone and temperature. The simulations include UV forcing at the top of the atmosphere, which includes a generic 27-day solar rotation effect as well as the observed monthly values of the solar fluxes. The results are analysed for the 27-day and 11-year cycles in temperature and ozone. In accordance with previous results, the 27-day cycle results are in good qualitative agreement with observations, particularly for ozone. However, the results show significant variations, typically a factor of two or more in sensitivity to solar flux, depending on the solar cycle. In the lower and middle stratosphere we show good agreement also between the modelled and observed 11-year cycle results for the ozone vertical profile averaged over low latitudes. In particular, the minimum in solar response near 20 hPa is well simulated. In comparison, experiments of the model with fixed solar phase (solar maximum/solar mean) and climatological sea surface temperatures lead to a poorer simulation of the solar response in the ozone vertical profile, indicating the need for variable phase simulations in solar sensitivity experiments. The role of sea surface temperatures and tropical upwelling in simulating the ozone minimum response are also discussed.

  12. Seasonal cycle of solar energy fluxes through Arctic sea ice

    Directory of Open Access Journals (Sweden)

    S. Arndt

    2014-06-01

    Full Text Available Arctic sea ice has not only decreased considerably during the last decades, but also changed its physical properties towards a thinner and more seasonal cover. These changes strongly impact the energy budget and might affect the ice-associated ecosystem of the Arctic. But until now, it is not possible to quantify shortwave energy fluxes through sea ice sufficiently well over large regions and during different seasons. Here, we present a new parameterization of light transmittance through sea ice for all seasons as a function of variable sea ice properties. The annual maximum solar heat flux of 30 × 105 J m−2 occurs in June, then also matching the under ice ocean heat flux. Furthermore, our results suggest that 96% of the total annual solar heat input occurs from May to August, during four months only. Applying the new parameterization on remote sensing and reanalysis data from 1979 to 2011, we find an increase in light transmission of 1.5% a−1 for all regions. Sensitivity studies reveal that the results strongly depend on the timing of melt onset and the correct classification of ice types. Hence, these parameters are of great importance for quantifying under-ice radiation fluxes and the uncertainty of this parameterization. Assuming a two weeks earlier melt onset, the annual budget increases by 20%. Continuing the observed transition from Arctic multi- to first year sea ice could increase light transmittance by another 18%. Furthermore, the increase in light transmission directly contributes to an increase in internal and bottom melt of sea ice, resulting in a positive transmittance-melt feedback process.

  13. Magnetic flux density in the heliosphere through several solar cycles

    Energy Technology Data Exchange (ETDEWEB)

    Erdős, G. [Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Balogh, A., E-mail: erdos.geza@wigner.mta.hu [The Blackett Laboratory, Imperial College London, London SW7 2BZ (United Kingdom)

    2014-01-20

    We studied the magnetic flux density carried by solar wind to various locations in the heliosphere, covering a heliospheric distance range of 0.3-5.4 AU and a heliolatitudinal range from 80° south to 80° north. Distributions of the radial component of the magnetic field, B{sub R} , were determined over long intervals from the Helios, ACE, STEREO, and Ulysses missions, as well as from using the 1 AU OMNI data set. We show that at larger distances from the Sun, the fluctuations of the magnetic field around the average Parker field line distort the distribution of B{sub R} to such an extent that the determination of the unsigned, open solar magnetic flux density from the average (|B{sub R} |) is no longer justified. We analyze in detail two methods for reducing the effect of fluctuations. The two methods are tested using magnetic field and plasma velocity measurements in the OMNI database and in the Ulysses observations, normalized to 1 AU. It is shown that without such corrections for the fluctuations, the magnetic flux density measured by Ulysses around the aphelion phase of the orbit is significantly overestimated. However, the matching between the in-ecliptic magnetic flux density at 1 AU (OMNI data) and the off-ecliptic, more distant, normalized flux density by Ulysses is remarkably good if corrections are made for the fluctuations using either method. The main finding of the analysis is that the magnetic flux density in the heliosphere is fairly uniform, with no significant variations having been observed either in heliocentric distance or heliographic latitude.

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

    Science.gov (United States)

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

    2016-09-01

    We investigate the characteristics and the sources of the slow ( {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.

  15. Science and cycling: current knowledge and future directions for research.

    Science.gov (United States)

    Atkinson, Greg; Davison, Richard; Jeukendrup, Asker; Passfield, Louis

    2003-09-01

    In this holistic review of cycling science, the objectives are: (1) to identify the various human and environmental factors that influence cycling power output and velocity; (2) to discuss, with the aid of a schematic model, the often complex interrelationships between these factors; and (3) to suggest future directions for research to help clarify how cycling performance can be optimized, given different race disciplines, environments and riders. Most successful cyclists, irrespective of the race discipline, have a high maximal aerobic power output measured from an incremental test, and an ability to work at relatively high power outputs for long periods. The relationship between these characteristics and inherent physiological factors such as muscle capilliarization and muscle fibre type is complicated by inter-individual differences in selecting cadence for different race conditions. More research is needed on high-class professional riders, since they probably represent the pinnacle of natural selection for, and physiological adaptation to, endurance exercise. Recent advances in mathematical modelling and bicycle-mounted strain gauges, which can measure power directly in races, are starting to help unravel the interrelationships between the various resistive forces on the bicycle (e.g. air and rolling resistance, gravity). Interventions on rider position to optimize aerodynamics should also consider the impact on power output of the rider. All-terrain bicycle (ATB) racing is a neglected discipline in terms of the characterization of power outputs in race conditions and the modelling of the effects of the different design of bicycle frame and components on the magnitude of resistive forces. A direct application of mathematical models of cycling velocity has been in identifying optimal pacing strategies for different race conditions. Such data should, nevertheless, be considered alongside physiological optimization of power output in a race. An even distribution

  16. STATISTICAL STUDY OF STRONG AND EXTREME GEOMAGNETIC DISTURBANCES AND SOLAR CYCLE CHARACTERISTICS

    Energy Technology Data Exchange (ETDEWEB)

    Kilpua, E. K. J. [Department of Physics, University Helsinki (Finland); Olspert, N.; Grigorievskiy, A.; Käpylä, M. J.; Tanskanen, E. I.; Pelt, J. [ReSoLVE Centre of Excellence, Department of Computer Science, P.O. Box 15400, FI-00076 Aalto Univeristy (Finland); Miyahara, H. [Musashino Art University, 1-736 Ogawa-cho, Kodaira-shi, Tokyo 187-8505 (Japan); Kataoka, R. [National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)

    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.

  17. Entropy Analysis of Solar Two-Step Thermochemical Cycles for Water and Carbon Dioxide Splitting

    Directory of Open Access Journals (Sweden)

    Matthias Lange

    2016-01-01

    Full Text Available The present study provides a thermodynamic analysis of solar thermochemical cycles for splitting of H2O or CO2. Such cycles, powered by concentrated solar energy, have the potential to produce fuels in a sustainable way. We extend a previous study on the thermodynamics of water splitting by also taking into account CO2 splitting and the influence of the solar absorption efficiency. Based on this purely thermodynamic approach, efficiency trends are discussed. The comprehensive and vivid representation in T-S diagrams provides researchers in this field with the required theoretical background to improve process development. Furthermore, results about the required entropy change in the used redox materials can be used as a guideline for material developers. The results show that CO2 splitting is advantageous at higher temperature levels, while water splitting is more feasible at lower temperature levels, as it benefits from a great entropy change during the splitting step.

  18. Economic optimization of a Kalina cycle for a parabolic trough solar thermal power plant

    DEFF Research Database (Denmark)

    Modi, Anish; Kærn, Martin Ryhl; Andreasen, J. G.

    2015-01-01

    The Kalina cycle has recently seen increased interest as a replacement for the more traditional steam Rankine cycle for geothermal, solar, ocean thermal energy conversion and waste heat recovery applications. The Kalina cycle uses a mixture of ammonia and water as the working fluid. The ammonia-water...... mixture evaporates and condenses with a temperature glide, thus providing a better match with the heat source/sink temperature profile. This better match results in reduced thermal irreversibility, but at the cost of relatively larger heat exchanger areas. The parabolic trough collector is the most mature...

  19. Filaments disappearances in relation to solar flares during the solar cycle 23

    Science.gov (United States)

    Mawad, R.; Shaltout, Mosalam; Ewaida, M.; Yousef, M.; Yousef, S.

    2015-01-01

    We studied the association between the filament disappearances and solar flares during 1996-2010; we listed 639 associated filament disappearances with solar flares under temporal and spatial condition, those particular 639 filament disappearance were associated with 1676 solar flares during the period 1996-2010. The best angular distance between filament disappearances and associated solar flares ranged between 30° and 60°. The number of the associated events increased with increasing solar activity and decreased with quiet sun. The location of filament disappearances ranges between latitude ±50° and longitude ±70°. We found that longer filament disappearances have activity and ability of contemporary association with flares more than shorter filament disappearance, filament disappearance powers the associated flares more than non-associated flares events. The associated flares have higher solar flux, longer duration, and higher importance compared to non-associated flares with filament disappearance. In addition the associated filament disappearance with flares have two types depending on their duration, short-lived (9 h).

  20. Unusual Polar Activity of the Sun in the Northern Hemisphere and Its Implications for Solar Cycle 25

    Science.gov (United States)

    Gopalswamy, Nat; Masuda, Satoshi; Yashiro, Seiji; Akiyama, Sachiko; Shibasaki, Kiyoto

    2016-07-01

    Polar field strength in one solar cycle is known to indicate the strength (e.g., Sunspot number) and phase of the next cycle. In particular the polar field strength (or its proxies such as the polar coronal hole area and microwave polar brightness) during the minimum phase of a given cycle seem to be well correlated with the maximum sunspot number of the next cycle. Polar prominence eruptions and coronal mass ejections have also been found to be indicators of low polar field; their cessation signals the time of polarity reversal. While these indicators are present in the current cycle, significant differences are found regarding the phase lag between the two hemispheres and the duration of polar eruptions. We use data from the Nobeyama Radioheliograph, the Solar Dynamics Observatory, SOLIS, and Wilcox Solar Observatory to highlight these differences. We find that the north polar region of the Sun has near-zero field strength for more than three years. This is unusually long and caused by surges of both polarities heading toward the north pole that prevent the buildup of the polar field. This seems to be due to anti-Hale active regions that appeared around the 2012 peak sunspot activity in the northern hemisphere. The unusual condition is consistent with (i) the continued high-latitude prominence eruption, (ii) the extended period of high tilt angle of the heliospheric current sheet, (iii) the weak microwave polar brightness, and (iv) the lack of north polar coronal hole. On the other hand, the south polar field has started building up and the coronal hole has appeared in early 2015 because of large active regions of the correct tilt in the southern hemisphere during the 2014 peak of sunspot activity. The extended period of near-zero field in the north polar region should result in very weak and delayed sunspot activity in the northern hemisphere in cycle 25. On the other hand the south polar field has already increased significantly, suggesting that the activity in

  1. Secular variation of hemispheric phase differences in the solar cycle

    CERN Document Server

    Zolotova, N V; Arlt, R; Tuominen, I

    2010-01-01

    We investigate the phase difference of the sunspot cycles in the two hemispheres and compare it with the latitudinal sunspot distribution. If the north-south phase difference exhibits a long-term tendency, it should not be regarded as a stochastic phenomenon. We use datasets of historical sunspot records and drawings made by Staudacher, Hamilton, Gimingham, Carrington, Spouml;rer, and Greenwich observers, as well as the sunspot activity during the Maunder minimum reconstructed by Ribes and Nesme-Ribes. We employ cross-recurrence plots to analyse north-south phase differences. We show that during the last 300 years, the persistence of phase-leading in one of the hemispheres exhibits a secular variation. Changes from one hemisphere to the other leading in phase were registered near 1928 and 1968 as well as two historical ones near 1783 and 1875. A long-term anticorrelation between the hemispheric phase differences in the sunspot cycles and the latitudinal distribution of sunspots was traced since 1750.

  2. Magnetic activity in the young solar analog LQ Hydrae. I. Active longitudes and cycles

    Science.gov (United States)

    Berdyugina, S. V.; Pelt, J.; Tuominen, I.

    2002-11-01

    We present the first evidence that a single active dwarf of solar type can show a long-lived, nonaxisymmetric spot distribution - active longitudes on opposite hemispheres, similar to evolved, rapidly rotating RS CVn-type binary stars. We analyse new as well as published photometric observations of the young active dwarf LQ Hya, spanning almost 20 years. We find that activity of the star has three activity cycles: a 5.2-yr ``flip-flop'' cycle, a 7.7-yr period in the amplitude modulation of the brightness and an approximately 15-yr period in variations of the mean brightness. The two shorter cycles are related to the alternating active longitudes and are similar to cycles observed in RS CVn-type stars. The 15-yr cycle reflects periodic changes of the mean spottedness of the star and resembles the solar 11-year cycle. The spot rotation period (about 1.6 days) changes during the 15-yr cycle, indicating the presence of small differential rotation. The lengths of the three cycles are related as 3:2:1, with the repetition of the spot configuration after 15 years. We discuss the possibility that the observed spot cycles represent two different magnetic dynamo modes operating in LQ Hya: an axisymmetric mode, as in the Sun, and a nonaxisymmetric higher order mode with two cycles in spot patterns. Our results suggest that young stars exhibit their cycles in spot distribution, as seen in LQ Hya. This is in contrast to the conclusion based on the analysis of Ca Ii H&K emission from plages. The results suggest also that the Vaughan-Preston gap represents a transition from a multiple-mode dynamo to a single-mode dynamo. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/394/505

  3. Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, M.A. (Univ. of Pittsburgh, PA (United States)); Meriwether, J.W. Jr. (Air Force Geophysics Lab., Hanscom AFB, MA (United States)); Fejer, B.G.; Gonzalez, S.A. (Utah State Univ., Logan (United States)); Hallenbeck, D.C. (NASA Laser Tracking Station, Arequipa (Peru))

    1991-09-01

    Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over {approximately} 2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the expected, underlying forcing and damping processes. For most of the years, at the winter solstice, there is a weak ({le} 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). The zonal flows are predominantly eastward throughout the night, except for the solar minimum equinoxes, where brief westward flows appear in the early and the late night. The peak eastward velocities increase toward solar maximum; at the winter solstice, they are {approximately} 100-130 m/s in 1983, 1984 and 1986, reaching {approximately} 200 m/s in 1988, 1989 and 1990. The present equatorial thermospheric wind determinations agree in some respects with the satellite-data-based horizontal wind model IIWM-87 and the vector spherical harmonic form of the thermospheric general circulation model.

  4. Analysis of the solar cycle and core rotation using 15 years of Mark-I observations 1984-1999. I. The solar cycle

    CERN Document Server

    Jiménez-Reyes, S J; Pallé, P L; Cortés, T R; Tomczyk, S

    2001-01-01

    High quality observations of the low-degree acoustic modes (p-modes) exist for almost two complete solar cycles using the solar spectrophotometer Mark-I, located at the Observatorio del Teide (Tenerife, Spain) and operating now as part of the Birmingham Solar Oscillations Network (BiSON). We have performed a Fourier analysis of 30 calibrated time-series of one year duration covering a total period of 15 years between 1984 and 1999. Applying different techniques to the resulting power spectra, we study the signature of the solar activity changes on the low-degree p-modes. We show that the variation of the central frequencies and the total velocity power (TVP) changes. A new method of simultaneous fit is developed and a special effort has been made to study the frequency-dependence of the frequency shift. The results confirm a variation of the central frequencies of acoustic modes of about 450 nHz, peak-to-peak, on average for low degree modes between 2.5 and 3.7 mHz. The TVP is anti-correlated with the common ...

  5. iota Horologi, the first coronal activity cycle in a young solar-like star

    CERN Document Server

    Sanz-Forcada, J; Metcalfe, T S; 10.1051/0004-6361/201321388

    2013-01-01

    Context: The shortest chromospheric (Ca II H&K) activity cycle (1.6 yr) has been recently discovered in the young (~600 Myr) solar-like star iota Hor. Coronal X-ray activity cycles have only been discovered in a few stars other than the Sun, all of them with an older age and a lower activity level than iota Hor. Aims: We intended to find the X-ray coronal counterpart of the chromospheric cycle for i Hor. This represents the first X-ray cycle observed in an active star, as well as the paradigm of the first coronal cycles in the life of a solar-like star. Methods: We monitored i Hor with XMM-Newton observations spanning almost two years. The spectra of each observation are fit with two-temperature coronal models to study the long-term variability of the star. Results: We find a cyclic behavior in X-rays very similar to the contemporaneous chromospheric cycle. The continuous chromospheric monitoring for more than three cycle lengths shows a trend toward decreasing amplitude, apparently modulated by a longer ...

  6. Climatology of low latitude ionosphere under effect of varying solar flux during solar cycle 23 and 24

    Science.gov (United States)

    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

  7. Formation of a strong southward IMF near the solar maximum of cycle 23

    Directory of Open Access Journals (Sweden)

    S. Watari

    2004-01-01

    Full Text Available We analyzed observations of the solar activities and the solar wind parameters associated with large geomagnetic storms near the maximum of solar cycle 23. This analysis showed that strong southward interplanetary magnetic fields (IMFs, formed through interaction between an interplanetary disturbance, and background solar wind or between interplanetary disturbances are an important factor in the occurrence of intense geomagnetic storms. Based on our analysis, we seek to improve our understanding of the physical processes in which large negative Bz's are created which will lead to improving predictions of space weather.

    Key words. Interplanetary physics (Flare and stream dynamics; Interplanetary magnetic fields; Interplanetary shocks

  8. The acoustic cut-off frequency of the Sun and the solar magnetic activity cycle

    CERN Document Server

    Jimenez, A; Palle, P L

    2011-01-01

    The acoustic cut-off 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 traveling waves. Interference amongst them give 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 cut-off frequency. Using data from GOLF and VIRGO instruments on board the SOHO spacecraft, we calculate the acoustic cut-off 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 till the present), a variation in the acoustic cut-off frequency with the solar magnetic activity cycle is found.

  9. Cloud optical thickness variations during 1983-1991: Solar cycle or ENSO?

    Science.gov (United States)

    Kuang, Zhiming; Jiang, Yibo; Yung, Yuk L.

    Based on a detailed analysis of the cloud data obtained by the International Satellite Cloud Climatology Project (ISCCP) in the years 1983-1991, we show that besides the reported 3% variation in global cloudiness (Svensmark and Friis-Christensen, 1997), the global mean cloud optical thickness (MCOT) also has significant variation which is out of phase with that of the global cloudiness. The combined effect of the two opposing variations may be a null effect on the cloud reflectivity. These results are consistent with the Total Ozone Mapping Spectrometer (TOMS) reflectivity measurements. The MCOT variation is further shown to be correlated with both the solar cycle and the ENSO cycle. Our present analysis cannot distinguish which of the above two provides better correlation, although independent data from the High resolution Infrared Radiation Sounder (HIRS) from 1990 to 1996 favor the solar cycle. Future data are needed to identify the true cause of these changes.

  10. A new solar signal: Average maximum sunspot magnetic fields independent of activity cycle

    CERN Document Server

    Livingston, William

    2016-01-01

    Over the past five years, 2010-2015, we have observed, in the near infrared (IR), the maximum magnetic field strengths for 4145 sunspot umbrae. Herein we distinguish field strengths from field flux. (Most solar magnetographs measure flux). Maximum field strength in umbrae is co-spatial with the position of umbral minimum brightness (Norton and Gilman, 2004). We measure field strength by the Zeeman splitting of the Fe 15648.5 A spectral line. We show that in the IR no cycle dependence on average maximum field strength (2050 G) has been found +/- 20 Gauss. A similar analysis of 17,450 spots observed by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory reveal the same cycle independence +/- 0.18 G., or a variance of 0.01%. This is found not to change over the ongoing 2010-2015 minimum to maximum cycle. Conclude the average maximum umbral fields on the Sun are constant with time.

  11. Solar-Cycle Variation of Subsurface-Flow Divergence: A Proxy of Magnetic Activity?

    Science.gov (United States)

    Komm, R.; Howe, R.; Hill, F.

    2017-09-01

    We study the solar-cycle variation of subsurface flows from the surface to a depth of 16 Mm. We have analyzed Global Oscillation Network Group (GONG) Dopplergrams with a ring-diagram analysis covering about 15 years and Helioseismic and Magnetic Imager (HMI) Dopplergrams covering more than 6 years. After subtracting the average rotation rate and meridional flow, we have calculated the divergence of the horizontal residual flows from the maximum of Solar Cycle 23 through the declining phase of Cycle 24. The subsurface flows are mainly divergent at quiet regions and convergent at locations of high magnetic activity. The relationship is essentially linear between divergence and magnetic activity at all activity levels at depths shallower than about 10 Mm. At greater depths, the relationship changes sign at locations of high activity; the flows are increasingly divergent at locations with a magnetic activity index (MAI) greater than about 24 G. The flows are more convergent by about a factor of two during the rising phase of Cycle 24 than during the declining phase of Cycle 23 at locations of medium and high activity (about 10 to 40 G MAI) from the surface to at least 10 Mm. The subsurface divergence pattern of Solar Cycle 24 first appears during the declining phase of Cycle 23 and is present during the extended minimum. It appears several years before the magnetic pattern of the new cycle is noticeable in synoptic maps. Using linear regression, we estimate the amount of magnetic activity that would be required to generate the precursor pattern and find that it should be almost twice the amount of activity that is observed.

  12. The onset of the new solar modulation cycle in 1987-1988 as a function of heliocentric radius and latitude

    Science.gov (United States)

    Webber, W. R.; Lockwood, J. A.

    1990-01-01

    The onset of a new solar modulation cycle were studied in 1987 and 1988, on the basis of data on counting rates of particles with E greater than 60 MeV, observed at the IMP, Voyager (V), and Pioneer (P) satellites. It was found that the decrease at earth was rapid after the intensity maximum in early 1987 and was closely correlated with the increase in the average tilt of the heliospheric current sheet. The initial rapid intensity decrease was found to be related to three small Forbush decreases which are superimposed on a more gradual decrease. By the end of 1988, the intensity decreased by about 40 percent at earth, 30 percent at V2, and 18 percent at P10. This overall decrease was accompanied by an increase in the average integral radial gradient as well as a decrease in the radial dependence of the gradient. The onset of the new solar modulation cycle seems to be related to the complete altering of the solar magnetic structure as observed on the surface of the sun.

  13. Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

    Indian Academy of Sciences (India)

    Vojtech Rusin; Milan Minarovjech; Milan Rybansky

    2000-09-01

    Long-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18-23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around' cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

  14. Mars plasma system response to ICME transients at different phases of the solar cycle

    Science.gov (United States)

    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.

  15. Variation of the Mn I 539.4 nm line with the solar cycle

    Science.gov (United States)

    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

  16. Refined life-cycle assessment of polymer solar cells

    DEFF Research Database (Denmark)

    Lenzmann, F.; Kroon, J.; Andriessen, R.

    2011-01-01

    with other PV technologies. It is shown that on a m2 basis the environmental characteristics of polymer-OPV are highly beneficial, while on a watt-peak and on a kWh basis, these benefits are - at the current level of the development - still (over-)compensated by low module efficiency and limited lifetime...

  17. Short circuit current in indium tin oxide/silicon solar cells

    Science.gov (United States)

    Singh, R.

    1980-09-01

    The short-circuit current density of indium tin oxide/single and polycrystalline silicon solar cells reported by Schunck and Coche (1979) is much higher than other silicon solar cells. It is shown that the short-circuit current density reported in the above reference does not represent the true value of these devices.

  18. Material cycling solar system modeled ecosystem; Seitaikei wo model to shita busshitsu junkangata solar system

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M. [Hachinohe Institute of Technology, Aomori (Japan)

    1996-10-27

    It is proposed to establish an integrated system close to a natural ecosystem for an industrial complex, taking that in Hachinohe City, Aomori Pref. as the conceptual site. It is a system in which materials are recycled by solar energy and industrial waste heat for a complex food industry. The conceptual site, although blessed with various marine products, are sometimes attacked by cold weather. Waste heat from a 250,000kW power plant, if transported by EHD heat pipes to the site, could provide roughly 400 times the heat required for production of agricultural and marine products, such as cabbages and fish meat. The waste heat, coupled with solar energy, should solve the problems resulting from hot waste water, if they could be utilized for the industrial purposes. The food industrial site that produces agricultural and marine products is considered to be suited as the center of the solar industrial complex incorporating farms. 5 refs., 3 figs.

  19. One thousand thermal cycles of magnesium chloride hexahydrate as a promising PCM for indoor solar cooking

    Energy Technology Data Exchange (ETDEWEB)

    El-Sebaii, A.A., E-mail: aasebaii@yahoo.co [Physics Department, Faculty of Science, King Abdul Aziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Al-Heniti, S.; Al-Agel, F.; Al-Ghamdi, A.A.; Al-Marzouki, F. [Physics Department, Faculty of Science, King Abdul Aziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2011-04-15

    Research highlights: {yields} Solar cookers must contain a PCM for cooking indoors. {yields} MgCl{sub 2}.6H{sub 2}O when it cycled in a sealed container. {yields} MgCl{sub 2}.6H{sub 2}O shows maximum of 0.1-3.5 {sup o}C of supercooling. {yields} MgCl{sub 2}.6H{sub 2}O is a promising PCM for thermal energy storage. -- Abstract: Cooking is the major necessity for people all over the world. It accounts for a major share of energy consumption in developing countries. There is a critical need for the development of alternative, appropriate, affordable methods of cooking for use in developing countries. There is a history for solar cooking since 1650 where they are broadly divided into direct or focusing type, box-type and indirect or advanced solar cookers. The advanced solar cookers have the advantage of being usable indoors and thus solve one of the problems, which impede the social acceptance of solar cookers. The advanced type solar cookers are employing additional solar units that increase the cost. Therefore, the solar cooker must contain a heat storage medium to store thermal energy for use during off-sunshine hours. The main aim of this paper is to investigate the influence of the melting/solidification fast thermal cycling of commercial grade magnesium chloride hexahydrate (MgCl{sub 2}.6H{sub 2}O) on its thermo-physical properties; such as melting point and latent heat of fusion, to be used as a storage medium inside solar cookers. One thousand cycles have been performed in a sealed container under the extra water principle. The thermo-physical properties are measured using the differential scanning calorimetric technique. It is indicated that MgCl{sub 2}.6H{sub 2}O with the extra water principle and hermetically sealing of the container is a promising phase change material (PCM) for cooking indoors and during law intensity solar radiation periods. It is also found from the melting/solidification behavior of MgCl{sub 2}.6H{sub 2}O that it is solidify almost

  20. Sub- and Quasi-Centurial Cycles in Solar and Geomagnetic Activity Data Series

    Science.gov (United States)

    Komitov, B.; Sello, S.; Duchlev, P.; Dechev, M.; Penev, K.; Koleva, K.

    2016-07-01

    The subject of this paper is the existence and stability of solar cycles with durations in the range of 20-250 years. Five types of data series are used: 1) the Zurich series (1749-2009 AD), the mean annual International sunspot number Ri, 2) the Group sunspot number series Rh (1610-1995 AD), 3) the simulated extended sunspot number from Extended time series of Solar Activity Indices (ESAI) (1090-2002 AD), 4) the simulated extended geomagnetic aa-index from ESAI (1099-2002 AD), 5) the Meudon filament series (1919-1991 AD). Two principally independent methods of time series analysis are used: the T-R periodogram analysis (both in standard and ``scanning window'' regimes) and the wavelet-analysis. The obtained results are very similar. A strong cycle with a mean duration of 55-60 years is found to exist in all series. On the other hand, a strong and stable quasi 110-120 years and ˜200-year cycles are obtained in all of these series except in the Ri one. The high importance of the long term solar activity dynamics for the aims of solar dynamo modeling and predictions is especially noted.

  1. Combined cycle solar central receiver hybrid power system study. Final technical report. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-11-01

    This study develops the conceptual design for a commercial-scale (nominal 100 MWe) central receiver solar/fossil fuel hybrid power system with combined cycle energy conversion. A near-term, metallic heat pipe receiver and an advanced ceramic tube receiver hybrid system are defined through parametric and market potential analyses. Comparative evaluations of the cost of power generation, the fuel displacement potential, and the technological readiness of these two systems indicate that the near-term hybrid system has better potential for commercialization by 1990. Based on the assessment of the conceptual design, major cost and performance improvements are projected for the near-term system. Constraints preventing wide-spread use were not identified. Energy storage is not required for this system and analyses show no economic advantages with energy storage provisions. It is concluded that the solar hybrid system is a cost effective alternative to conventional gas turbines and combined cycle generating plants, and has potential for intermediate-load market penetration at 15% annual fuel escalation rate. Due to their flexibility, simple solar/nonsolar interfacing, and short startup cycles, these hybrid plants have significant operating advantages. Utility company comments suggest that hybrid power systems will precede stand-alone solar plants.

  2. Effect of operating current dependent series resistance on the fill factor of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Dadu, Meena; Kapoor, A.; Tripathi, K.N. [Department of Electronic Science, University of Delhi, South Campus, Benito Juarez road, -110 021 New Delhi (India)

    2002-02-01

    The fill factor of a solar cell depends upon the series resistance, reverse saturation current, diode quality factor, operating current and voltage. Since the series resistance itself depends upon the operating current (or voltage), it makes the evaluation of fill factor very complicated. In this paper, we have evaluated the fill factor of a solar cell, taking into account operating current dependence of the series resistance.

  3. Simulation of an Innovative Stand-Alone Solar Desalination System Using an Organic Rankine Cycle

    Directory of Open Access Journals (Sweden)

    Jürgen Karl

    2007-12-01

    Full Text Available

    The rising of the world’s population leads automatically to the rising of water demand. As a consequence the lack of drinking water increases. Since a large part of the world’s population is concentrated in coastal areas, the desalination of seawater seems to be a promising solution. An innovative stand-alone solar desalination system could be used to produce drinking water from seawater. The great advantage of such a system is that it combines efficient desalination technology, reverse osmosis, with a renewable energy source, solar radiation. Thermal energy produced by the solar array evaporates a working fluid, which is used in an organic Rankine cycle that drives the pumps needed for the reverse osmosis process. Due to the fluctuation of solar irradiation, the dynamic simulation of such a system is necessary in order to assure the sufficient supply of water throughout a year. The simulation provides important information for optimum system sizing and design. The aim of this work is to present a modelling of a solar desalination system and to investigate the impact of different working fluids, thermodynamic parameters and cycle variations on the efficiency and water production of such a system.

    • An initial version of this paper was published in October, 2005 in the proceedings of SIMS'05, Trondheim, Norway. 

  4. A Running Average Method for Predicting the Size and Length of a Solar Cycle

    Institute of Scientific and Technical Information of China (English)

    Zhan-Le Du; Hua-Ning Wang; Li-Yun Zhang

    2008-01-01

    The running correlation coefficient between the solar cycle amplitudes and the max-max cycle lengths at a given cycle lag is found to vary roughly in a cyclical wave with the cycle number, based on the smoothed monthly mean Group sunspot numbers available since 1610. A running average method is proposed to predict the size and length of a solar cycle by the use of the varying trend of the coefficients. It is found that, when a condition (that the correlation becomes stronger) is satisfied, the mean prediction error (16.1) is much smaller than when the condition is not satisfied (38.7). This result can be explained by the fact that the prediction must fall on the regression line and increase the strength of the correlation. The method itself can also indicate whether the prediction is reasonable or not. To obtain a reasonable prediction, it is more important to search.for a running correlation coefficient whose varying trend satisfies the proposed condition, and the result does not depend so much on the size of the correlation coefficient. As an application, the peak sunspot number of cycle 24 is estimated as 140.4±15.7, and the peak as May 2012± 11 months.

  5. Estimate of Solar Maximum Using the 1-8 Angstrom Geostationary Operational Environmental Satellites X-Ray Measurements

    Science.gov (United States)

    2014-12-12

    TYPE Journal Article 3. DATES COVERED (From - To) 01 Oct 2014 – 30 Nov 2014 4. TITLE AND SUBTITLE Estimate of Solar Maximum Using the 1–8 Å...predict the intensity and date of the solar maximum of the current solar cycle. The solar cycle 24 prediction panel3 (Biesecker & Prediction Panel 2007...statement of the solar cycle 24 prediction panel is available at http://www.swpc.noaa.gov/SolarCycle/SC24/. 2. DETERMINATION OF THE SOLAR CYCLE

  6. North-south asymmetry in small and large sunspot group activity and violation of even-odd solar cycle rule

    Science.gov (United States)

    Javaraiah, J.

    2016-07-01

    According to Gnevyshev-Ohl (G-O) rule an odd-numbered cycle is stronger than its preceding even-numbered cycle. In the modern time the cycle pair (22, 23) violated this rule. By using the combined Greenwich Photoheliographic Results (GPR) and Solar Optical Observing Network (SOON) sunspot group data during the period 1874-2015, and Debrecen Photoheliographic Data (DPD) of sunspot groups during the period 1974-2015, here we have found that the solar cycle pair (22, 23) violated the G-O rule because, besides during cycle 23 a large deficiency of small sunspot groups in both the northern and the southern hemispheres, during cycle 22 a large abundance of small sunspot groups in the southern hemisphere. In the case of large and small sunspot groups the cycle pair (22, 23) violated the G-O rule in the northern and southern hemispheres, respectively, suggesting the north-south asymmetry in solar activity has a significant contribution in the violation of G-O rule. The amplitude of solar cycle 24 is smaller than that of solar cycle 23. However, Coronal Mass Ejections (CMEs) rate in the rising phases of the cycles 23 and 24 are almost same (even slightly large in cycle 24). From both the SOON and the DPD sunspot group data here we have also found that on the average the ratio of the number (counts) of large sunspot groups to the number of small sunspot groups is larger in the rising phase of cycle 24 than that in the corresponding phase of cycle 23. We suggest this could be a potential reason for the aforesaid discrepancy in the CME rates during the rising phases of cycles 23 and 24. These results have significant implication on solar cycle mechanism.

  7. Dynamics of the photosphere along the solar cycle from SDO/HMI

    CERN Document Server

    Roudier, Th; Mirouh, G M

    2016-01-01

    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. We investigate the flow field during the solar cycle by analysing SDO/HMI observations of continuum intensity, Doppler velocity and longitudinal magnetic field. We first picked data at disk center during 6 years along the solar cycle with a 48-hour time step in order to study the overall evolution of the continuum intensity and magnetic field. Then we focused on thirty 6-hour 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 216.4Mm x 216.4Mm located at disk center. Our measurements at disk center show the stability of the flow properties between meso- and supergranular scales along the solar cycle. The network magnetic field, pro...

  8. Three Super Active Regions in the Descending Phase of Solar Cycle 23

    Institute of Scientific and Technical Information of China (English)

    Hong-Qi Zhang; Jiang-Tao Su; Juan Guo; Xiao-Fan Wang; Ke-Liang Hu; Gang-Hua Lin; Dong-Guang Wang; Xing-Ming Bao; Yin Zhang; Ji-Hong Liu; Shu-Dong Bao; Yuan-Yong Deng; Wei Li; Jie Chen; Jin-Ping Dun

    2003-01-01

    We analyze the magnetic configurations of three super active regions,NOAA 10484, 10486 and 10488, observed by the Huairou Multi-Channel Solar Telescope (MCST) from 2003 October 18 to November 4. Many energetic phenomena,such as flares (including a X-28 flare) and coronal mass ejections (CMEs), occurred during this period. We think that strong shear and fast emergence of magnetic flux are the main causes of these events. The question is also of great interest why these dramatic eruptions occurred so close together in the descending phase of the solar cycle.

  9. Solar magnetic activity cycles, coronal potential field models and eruption rates

    Science.gov (United States)

    Petrie, Gordon

    2013-07-01

    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 NSO's three magnetographs at Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun (SOLIS) vector spectro-magnetograph (VSM), the spectro-magnetograph and the 512-channel magnetograph instruments, and from the U. Stanford's Wilcox Solar Observatory. The associated multipole field components are used to study the dominant length scales and symmetries of the coronal field. 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 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 (CACTus), Solar Eruptive Event Detection System (SEEDS), and Nobeyama radioheliograph prominence eruption catalogs, the rate of solar eruptions is found to be systematically higher for active years between 2003-2012 than for those between 1997-2002. 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.

  10. Variability of space climate and its extremes with successive solar cycles

    Science.gov (United States)

    Chapman, Sandra; Hush, Phillip; Tindale, Elisabeth; Dunlop, Malcolm; Watkins, Nicholas

    2016-04-01

    Auroral geomagnetic indices coupled with in situ solar wind monitors provide a comprehensive data set, spanning several solar cycles. Space climate can be considered as the distribution of space weather. We can then characterize these observations in terms of changing space climate by quantifying how the statistical properties of ensembles of these observed variables vary between different phases of the solar cycle. We first consider the AE index burst distribution. Bursts are constructed by thresholding the AE time series; the size of a burst is the sum of the excess in the time series for each time interval over which the threshold is exceeded. The distribution of burst sizes is two component with a crossover in behaviour at thresholds ≈ 1000 nT. Above this threshold, we find[1] a range over which the mean burst size is almost constant with threshold for both solar maxima and minima. The burst size distribution of the largest events has a functional form which is exponential. The relative likelihood of these large events varies from one solar maximum and minimum to the next. If the relative overall activity of a solar maximum/minimum can be estimated, these results then constrain the likelihood of extreme events of a given size for that solar maximum/minimum. We next develop and apply a methodology to quantify how the full distribution of geomagnetic indices and upstream solar wind observables are changing between and across different solar cycles. This methodology[2] estimates how different quantiles of the distribution, or equivalently, how the return times of events of a given size, are changing. [1] Hush, P., S. C. Chapman, M. W. Dunlop, and N. W. Watkins (2015), Robust statistical properties of the size of large burst events in AE, Geophys. Res. Lett.,42 doi:10.1002/2015GL066277 [2] Chapman, S. C., D. A. Stainforth, N. W. Watkins, (2013) On estimating long term local climate trends , Phil. Trans. Royal Soc., A,371 20120287 DOI:10.1098/rsta.2012.0287

  11. Algae biodiesel life cycle assessment using current commercial data.

    Science.gov (United States)

    Passell, Howard; Dhaliwal, Harnoor; Reno, Marissa; Wu, Ben; Ben Amotz, Ami; Ivry, Etai; Gay, Marcus; Czartoski, Tom; Laurin, Lise; Ayer, Nathan

    2013-11-15

    Autotrophic microalgae represent a potential feedstock for transportation fuels, but life cycle assessment (LCA) studies based on laboratory-scale or theoretical data have shown mixed results. We attempt to bridge the gap between laboratory-scale and larger scale biodiesel production by using cultivation and harvesting data from a commercial algae producer with ∼1000 m(2) production area (the base case), and compare that with a hypothetical scaled up facility of 101,000 m(2) (the future case). Extraction and separation data are from Solution Recovery Services, Inc. Conversion and combustion data are from the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model (GREET). The LCA boundaries are defined as "pond-to-wheels". Environmental impacts are quantified as NER (energy in/energy out), global warming potential, photochemical oxidation potential, water depletion, particulate matter, and total NOx and SOx. The functional unit is 1 MJ of energy produced in a passenger car. Results for the base case and the future case show an NER of 33.4 and 1.37, respectively and GWP of 2.9 and 0.18 kg CO2-equivalent, respectively. In comparison, petroleum diesel and soy diesel show an NER of 0.18 and 0.80, respectively and GWP of 0.12 and 0.025, respectively. A critical feature in this work is the low algal productivity (3 g/m(2)/day) reported by the commercial producer, relative to the much higher productivities (20-30 g/m(2)/day) reported by other sources. Notable results include a sensitivity analysis showing that algae with an oil yield of 0.75 kg oil/kg dry biomass in the future case can bring the NER down to 0.64, more comparable with petroleum diesel and soy biodiesel. An important assumption in this work is that all processes are fully co-located and that no transport of intermediate or final products from processing stage to stage is required.

  12. Solar Photovoltaic Development in Australia—A Life Cycle Sustainability Assessment Study

    Directory of Open Access Journals (Sweden)

    Man Yu

    2015-01-01

    Full Text Available Australia possesses the highest average solar radiation of any continent in the world, but solar energy in total contributes less than 1% to Australia’s primary energy consumption. This study intends to assess whether solar photovoltaic (PV is really a sustainable option for Australia’s energy transition on the project level. A life cycle sustainability assessment (LCSA was conducted on a 1.2 MW flat-roof mounted PV solar array called UQ Solar, and the results suggested UQ Solar performed well in environmental aspects, except for emissions of several criteria air pollutants. It was economically feasible only with the grant provided by the Queensland government and the levelized cost of electricity (LCOE was more or less the same as the LCOE of offset electricity. However, its social performance was not as good as expected. Large-scale PV installations can be sustainable in Australia on several conditions. PV manufacturers should be more responsible for reducing the use of hazardous materials; end-of-life treatment should be taken good care of; government should truly support the deployment of large-scale PV installation by providing more incentives and infrastructures; substantial subsidies for fossil fuel power stations should phase out; more awareness and training activities should be organized to promote social acceptance.

  13. DC current distribution mapping system of the solar panels using a HTS-SQUID gradiometer

    Science.gov (United States)

    Miyazaki, Shingo; Kasuya, Syohei; Mawardi Saari, Mohd; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Tsukada, Keiji

    2014-05-01

    Solar panels are expected to play a major role as a source of sustainable energy. In order to evaluate solar panels, non-destructive tests, such as defect inspections and response property evaluations, are necessary. We developed a DC current distribution mapping system of the solar panels using a High Critical Temperature Superconductor Superconducting Quantum Interference Device (HTS-SQUID) gradiometer with ramp edge type Josephson junctions. Two independent components of the magnetic fields perpendicular to the panel surface (∂Bz/∂x, ∂Bz/∂y) were detected. The direct current of the solar panel is visualized by calculating the composition of the two signal components, the phase angle, and mapping the DC current vector. The developed system can evaluate the uniformity of DC current distributions precisely and may be applicable for defect detection of solar panels.

  14. Solar and Space Weather Radiophysics Current Status and Future Developments

    CERN Document Server

    Gary, Dale E

    2005-01-01

    The book explores what can be learned about the Sun and interplanetary space using present-day and future radio observations and techniques. The emphasis is on interpretation of radio data with high spatial and spectral resolution, motivated by the planned construction of a new, powerful, solar-dedicated radio array called the Frequency Agile Solar Radiotelescope (FASR). The book is unique in exploring a broad frequency range, which corresponds to heights ranging from the low solar atmosphere out to the Earth. The book contains a thorough review of the entire field of solar and Space Weather radio research; gives background information suitable for advanced undergraduates, graduates, and researchers in solar and Space Weather research and related fields; and looks at what new results may be expected in the next two decades with FASR and other new instruments now under development. The individual chapters are written by international experts in each topic, and although each chapter may be read as a stand-alone...

  15. Solar Wind Structure Sources and Periodicites of Auroral Electron Power Over the Three Solar Cycles

    Science.gov (United States)

    2009-01-01

    Watari and Watanabe (2000) reported about half of the magnetic disturbances (mini- mum Dst<-50nT) in the solar minimum years of 1995-1997 were...7a and b. Watari and Watanabe (2000) remarked on the low geomagnetic activity during solstices between 1995 and 1997, with very low values in the...Analysis Software and Systems VI. ASP Conference Series, vol. 125. Watari . S„ Watanabe. T. 2000. High-speed streams from coronal holes and coronal mass

  16. Solar Spectral Irradiance Variability of Some Chromospheric Emission Lines Through the Solar Activity Cycles 21-23

    Science.gov (United States)

    Göker, Ü. D.; Gigolashvili, M. Sh.; Kapanadze, N.

    2017-02-01

    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 such as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We reduced these data by using the MATLAB software package. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) spectral lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar activity cycles (SACs) 23 and 24. We also compared our results with the variations of solar activity indices obtained by the ground-based telescopes. Therefore, we found that plage regions decrease while facular areas are increasing in SAC 23. However, the decrease in plage regions is seen in small sunspot groups (SGs), contrary to this, these regions in large SGs are comparable to previous SACs or even larger as is also seen in facular areas. Nevertheless, negative correlations between ISSN and SSI data indicate that these variations are in close connection with the classes of sunspots/SGs, faculae and plage regions. Finally, we applied the time series analysis of spectral lines corresponding to the wavelengths 121.5 nm-300.5 nm and made comparisons with the ISSN data. We found an unexpected increase in the 298.5 nm line for the Fe II ion. The variability of Fe II ion 298.5 nm line is in close connection with the facular areas and plage regions, and the sizes of these solar surface indices play an important role for the SSI variability, as well. So, we compared the connection between the sizes of faculae and plage regions, sunspots/SGs, chemical elements and SSI variability. Our future work will be the theoretical study of this connection and developing of a corresponding model.

  17. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Keya Zhou

    2015-07-01

    Full Text Available Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si and amorphous silicon (a-Si thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells.

  18. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications.

    Science.gov (United States)

    Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

    2015-07-22

    Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells.

  19. Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants

    Directory of Open Access Journals (Sweden)

    A. B. Kasaeian

    2013-04-01

    Full Text Available In this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω, compression ratio (rp and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e and R1234ze(z. The results show that R114 and R1234ze(e yield the highest COP and exergy efficiency followed by R123, R245fa, R365mfc, R141b, R152a and R600a. It is noticed that the COP value of the new solar ejector-vapor compression refrigeration cycle is higher than that of the conventional ejector cycle with R1234ze(e for all operating conditions. This paper also demonstrates that R1234ze(e will be a suitable refrigerant in the solar combined ejector-vapor compression refrigeration system, due to its environmental friendly properties and better performance. ABSTRAK: Kajian ini menganalisa model baru sistem penyejukan mampatan gabungan ejektor-wap solar.Sistem ini dilengkapi dengan penukar haba dalaman untuk meningkatkan prestasi kitaran.Kesan bendalir bekerja dan keadaan operasi pada prestasi sistem termasuk COP, nisbah pemerangkapan (ω, nisbah mampatan (rp dan kecekapan eksergi telah disiasat.Beberapa bendalir bekerja yang dicadangkan adalah: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e dan R1234ze(z.Hasil kajian menunjukkan R114 dan R1234ze(e menghasilkan COP dan kecekapan eksergi tertinggi diikuti oleh R123, R245fa, R365mfc, R141b, R152a dan R600a.Didapati nilai COP kitaran penyejukan mampatan bagi ejektor-wap solar baru adalah lebih tinggi daripada kitaran ejektor konvensional dengan R1234ze(e bagi semua keadaan operasi.Kertas kerja ini juga menunjukkan bahawa R1234ze(e boleh menjadi penyejuk yang sesuai dalam sistem penyejukan mampatan gabungan ejektor

  20. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    Science.gov (United States)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  1. Solar cycle length and 20th Century northern hemisphere warming: Revisited

    Science.gov (United States)

    Damon, Paul E.; Peristykh, Alexei N.

    It has been suggested that the length of the solar cycle (SCL) is related to solar forcing of global climate change [Friis-Christensen and Lassen, 1991]. Although no physical mechanism had been proposed, the relation seemed to be supported by interesting correlations with several paleoclimate records and, separately, with the 20th century Northern Hemisphere instrumental record. Actually, what has been correlated is the quasi-sinusoidal Gleissberg cycle which is slightly greater in the 18th century than in the 20th century. Using the pre-industrial record as a boundary condition, the SCL-temperature correlation corresponds to an estimated 25% of global warming to 1980 and 15% to 1997.

  2. Solar Cycle Fine Structure and Surface Rotation from Ca II K-Line Time Series Data

    Science.gov (United States)

    Scargle, Jeff; Keil, Steve; Worden, Pete

    2011-01-01

    Analysis of three and a half decades of data from the NSO/AFRL/Sac Peak K-line monitoring program yields evidence for four components to the variation: (a) the solar cycle, with considerable fine structure and a quasi-periodicity of 122.4 days; (b) a stochastic process, faster than (a) and largely independent of it, (c) a quasi-periodic signal due to rotational modulation, and of course (d) observational errors (shown to be quite small). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these chromospheric parameters. Time-frequency analysis is especially useful for extracting information about differential rotation, and in particular elucidates the connection between its behavior and fine structure of the solar cycle on approximately one-year time scales. These results further suggest that similar analyses will be useful at detecting and characterizing differential rotation in stars from stellar light-curves such as those being produced at NASA's Kepler observatory.

  3. Moon Connection with MEGA and Giant Earthquakes in Subduction Zones during One Solar Cycle

    Science.gov (United States)

    Hagen, M. T.; Azevedo, A. T.

    2016-12-01

    We investigated in this paper the possible influences of the moon on earthquakes during one Solar cycle. The Earth - Moon gravitational force produces a variation in the perigee force that may trigger seismological events. The oscillation force creates a wave that is generated by the moon rotation around the earth, which takes a month. The wave complete a cycle after 13- 14 months in average and the period is roughly 5400 hours as calculated. The major moon phases which are New and Full Moon is when the perigee force is stronger. The Solar Wind charges the Moon during the New phases. The plasmasphere charges the satellite during the Full Moon. Both create the Spring Tides what affects mostly the subduction zones connected with the Mega and Giant events in Pacific areas. Moon - Earth connections are resilient in locations with convergent tectonic plates. Inserted:

  4. Optimal design of compact organic Rankine cycle units for domestic solar applications

    Directory of Open Access Journals (Sweden)

    Barbazza Luca

    2014-01-01

    Full Text Available Organic Rankine cycle turbogenerators are a promising technology to transform the solar radiation harvested by solar collectors into electric power. The present work aims at sizing a small-scale organic Rankine cycle unit by tailoring its design for domestic solar applications. Stringent design criteria, i. e., compactness, high performance and safe operation, are targeted by adopting a multi-objective optimization approach modeled with the genetic algorithm. Design-point thermodynamic variables, e. g., evaporating pressure, the working fluid, minimum allowable temperature differences, and the equipment geometry, are the decision variables. Flat plate heat exchangers with herringbone corrugations are selected as heat transfer equipment for the preheater, the evaporator and the condenser. The results unveil the hyperbolic trend binding the net power output to the heat exchanger compactness. Findings also suggest that the evaporator and condenser minimum allowable temperature differences have the largest impact on the system volume and on the cycle performances. Among the fluids considered, the results indicate that R1234yf and R1234ze are the best working fluid candidates. Using flat plate solar collectors (hot water temperature equal to 75 °C, R1234yf is the optimal solution. The heat exchanger volume ranges between 6.0 and 23.0 dm3, whereas the thermal efficiency is around 4.5%. R1234ze is the best working fluid employing parabolic solar collectors (hot water temperature equal to 120 °C. In such case the thermal efficiency is around 6.9%, and the heat exchanger volume varies from 6.0 to 18.0 dm3.

  5. Application of solar hot water and geothermal principles to closed-cycle aquaculture

    Science.gov (United States)

    Yanzito, R. A.

    1981-04-01

    The design of an underground silo where warm water food fish could be raised to market size under controlled conditions. The building and solar concept analysis for the closed cycle aquaculture system are described. Energy conservation features of the design include Earth berming and insulation of the production silo and enclosure, a waste water reclaim system and a solar heating system. Much of the water surface area is covered with removable plants to minimize evaporative heat losses. An energy conservation analysis is also reported and the F-Chart computer program is described. The system chosen utilizes single glazed flat plate collectors in a closed loop antifreeze system. Makeup water is introduced during an 8 hour period each day. Solar energy is transferred from the antifreeze solution to the makeup water after it leaves the waste water heat exchanger.

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

    CERN Document Server

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

    2014-01-01

    The solar 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 100000 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.

  7. Online data base of satellite sounder and insitu measurements covering two solar cycles

    Science.gov (United States)

    Bilitza, D.; Reinisch, B.; Benson, R.; Grebowsky, J.; Papitashvili, N.; Huang, X.; Schar, W.; Hills, K.

    Accurate descriptions of the solar cycle variations of ionospheric parameters are an important goal of ionospheric modeling. Reliable predictions of these variations are of essential importance for almost all applications of ionospheric models. Unfortunately there are very few global data sources that cover a solar cycle or more. In an effort to expand the solar cycle coverage of data readily available for ionospheric modeling, we have processed a large number of satellite data sets from the sixties, seventies, and early eighties and have made them online accessible as part of NSSDC's ftp archive (http://nssdcftp.gsfc.nasa.gov/spacecraft data/) and it's ATMOWeb retrieval and plotting system (http://nssdc.gsfc.nasa.gov/atmoweb/). We report about two data restoration efforts supported through NASA's Applied Information Systems Research Program (AISRP). The first project deals with insitu data from a large number of US, Canadian, Japanese and German satellites that measured ionospheric densities and temperatures from 1964 to 1983. The accumulated data base includes data from the BE-B, DME-A, AE-B, Alouette 2, ISIS 1, 2, OGO-6, AEROS A, AE-C, -D, -E, Hinotori, ISS-b and DE-2 satellite missions. The second project involves the production of digital topside sounder ionograms from the ISIS 1 and 2 satellites and their subsequent inversion to produce electron-density profiles. Approximately 340,000 ionograms are available from NSSDC as of July 2002. An automatic topside ionogram scaler with true height algorithm (TOPIST) was developed as part of this project and is now being used to obtain electron density profiles from these ionograms. Providing global coverage over more than two solar cycles the database established by this two projects is a valuable asset for improvements of the International Reference Ionosphere model and for ionospheric research.

  8. Global Solar Convective Dynamo with Cycles, Equatorward Propagation and Grand Minima

    Science.gov (United States)

    Toomre, Juri; Augustson, Kyle C.; Brun, Allan Sacha; Miesch, Mark S.

    2016-05-01

    The 3-D MHD Anelastic Spherical Harmonic (ASH) code, using slope-limited diffusion, is used to study the interaction of turbulent convection, rotation and magnetism in a full spherical shell comparable to the solar convection zone. Here a star of one solar mass, with a solar luminosity, is considered that is rotating at three times the solar rate. The dynamo generated magnetic field forms large-scale toroidal wreaths, whose formation is tied to the low Rossby number of the convection in this simulation which we have labeled K3S. This case displays prominent polarity cycles with regular reversals occurring roughly every 6.2 years. These reversals are linked to the weakened differential rotation and a resistive collapse of the large-scale magnetic field. Distinctive equatorial migration of the strong magnetic wreaths is seen, arising from modulation of the differential rotation rather than a dynamo wave. As the wreaths approach the equator, cross-equatorial magnetic flux is achieved that permits the low-latitude convection to generate poloidal magnetic field with opposite polarity. Poleward migration of such magnetic flux from the equator eventually leads to the reversal of the polarity of the high-latitude magnetic field. This K3S simulation also enters an interval with reduced magnetic energy at low latitudes lasting roughly 16 years (about 2.5 polarity cycles), during which the polarity cycles are disrupted and after which the dynamo recovers its regular polarity cycles. An analysis of this striking grand minimum reveals that it likely arises through the interplay of symmetric and antisymmetric dynamo families.

  9. Spatial Structures of Polar Magnetic Field During the Last Solar Cycle

    Science.gov (United States)

    Sun, Xudong; Hoeksema, T.

    2009-05-01

    The Sun's polar field is closely related to the large scale coronal structure. It is important for coronal modeling and greatly affects the result. However, the polar field is not well observed because the ecliptic lies near the Sun's equator. In this study, we make use of the data from various observatories (MDI/WSO/MWO/Hinode) to study its spatial structures during the last solar cycle. The result is useful to improve the polar field extrapolation schemes.

  10. The climate response to the 11-yr solar cycle in the CMIP5 historical simulations

    Science.gov (United States)

    Misios, Stergios; Mitchell, Daniel; Tourpali, Kleareti; Gray, Lesley; Matthes, Katja

    2014-05-01

    The variation of the incoming solar irradiance over the course of the 11-yr solar cycle is a significant source of stratospheric variability. Dynamical mechanisms could amplify and transfer solar signals from the stratosphere to the troposphere and even the surface in a "top-down" pathway. In the opposite direction, "bottom-up" mechanisms could mediate solar signals from the surface to the troposphere via air-sea coupling. The Coupled Model Intercomparison Project Phase 5 (CMIP5) provides an unprecedented opportunity to understand the climate response to the 11-yr solar cycle, as brought about from both "top-down" and "bottom-up" mechanisms, because for the first time different coupled models are driven by spectral solar irradiance and ozone changes. We here analyse archived "historical" simulations (1850-2005) with a lead/lag multiple linear regression model, focusing onto the troposphere and oceans. Our analysis identifies a delayed warming in the troposphere and surface, which is explained by the delayed response of the oceans. In fact, the delayed warming penetrates down to ~150 m from the ocean surface. A significant warming is identified over the western Pacific and Indian oceans whereas an anomalous cooling is simulated in the eastern Pacific. This meridional temperature dipole introduces changes in the Walker circulation, precipitation, convective activity with concomitant effects on the Northern Pacific. We further categorize models in "low- and high-top, depending on the inclusion or not of detailed stratospheric dynamics. This classification is found educative when the relative role of the "top-down" versus "bottom-up" forcing is investigated.

  11. Combined solar organic Rankine cycle with reverse osmosis desalination process: Energy, exergy, and cost evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Nafey, A.S.; Sharaf, M.A. [Department of Engineering Science, Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

    2010-11-15

    Organic Rankine cycles (ORC) have unique properties that are well suited to solar power generation. In this work design and performance calculations are performed using MatLab/SimuLink computational environment. The cycle consists of thermal solar collectors (Flat Plate Solar Collector (FPC), or Parabolic Trough Collector (PTC), or Compound Parabolic Concentrator (CPC)) for heat input, expansion turbine for work output, condenser unit for heat rejection, pump unit, and Reverse Osmosis (RO) unit. Reverse osmosis unit specifications used in this work is based on Sharm El-Shiekh RO desalination plant. Different working fluids such as: butane, isobutane, propane, R134a, R152a, R245ca, and R245fa are examined for FPC. R113, R123, hexane, and pentane are investigated for CPC. Dodecane, nonane, octane, and toluene are allocated for PTC. The proposed process units are modeled and show a good validity with literatures. Exergy and cost analysis are performed for saturation and superheated operating conditions. Exergy efficiency, total exergy destruction, thermal efficiency, and specific capital cost are evaluated for direct vapor generation (DVG) process. Toluene and Water achieved minimum results for total solar collector area, specific total cost and the rate of exergy destruction. (author)

  12. The interplanetary magnetic field during solar cycle 21 ISEE-3/ICE observations

    Science.gov (United States)

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

    1986-01-01

    Temporal variations in the IMF during solar cycle 21 are investigated using magnetic field observations collected by the vector helium magnetometer on the ISEE-3/ICE spacecraft. Analysis of the observations reveal that the IMF magnitude, which had declined to 4.7 nT in 1976, peaked in late 1982 (two years after solar maximum) at 9.0 nT and rapidly decreased during 1983-1984 to an intensity of 6.2 nT in early 1985. The IMF intensities are compared with the auroral AE index; the observed peak in strength during 1981-1983 is related to a 50 percent increase in substorm activity levels. A decrease in Parker spiral angle, revealing the existence of high-speed streams is detected in the declining phase of the solar cycle. Variations in the intensity of the IMF correlate with Mt. Wilson magnetograph measurements of full disk magnetic flux. Source regions for the evolution of solar wind and the IMF are proposed.

  13. Variation of the Mn I 539.4 nm line with the solar cycle

    CERN Document Server

    Danilovic, S; Livingston, W; Krivova, N; Vince, I

    2015-01-01

    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. 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 might explain it. 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 using the model SATIRE-S. 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 ...

  14. Sub-surface Meridional Flow Results from MWO, GONG, and MDI during Solar Cycle 23

    Science.gov (United States)

    Pinkerton, Stephen; Rhodes, Edward J.; Bogart, Richard S.

    2014-06-01

    Time series of full-disk Dopplergrams were acquired at the 60-Foot Solar tower of the Mount Wilson Observatory every year between 1987 and 2009. Analysis of this archive revealed that the focal plane of the Tower did experience a small amount of systematic rotation, which suggested that the alignment of the optics had changed slightly over the years since its construction in 1907. This has caused some of the initial daily flow maps to possess a so-called “washing machine” effect similar to the pattern that was seen in raw GONG flow maps. We have incorporated a systematic program of ring-diagram analysis in which we have tracked the raw solar images using five differing assumed instrumental rotation rates. We have then gone on to compute synoptic maps of the horizontal flow vectors at several different depths over much of Solar Cycle 23 in order to study how such an instrumental rotation might affect both the zonal and meridional flows as functions of latitude, depth, and time. We compare these results with GONG and MDI flow measurements to empirically determine the regime within which the MWO results are reliable and extend our analysis into Solar Cycle 22.

  15. Correlation study of some solar activity indices in the cycles 21 - 23

    CERN Document Server

    Bruevich, E A

    2013-01-01

    The correlation coefficients of the linear regression of six solar indices versus F10,7 were analyzed in solar cycles 21, 22 and 23. We also analyzed the interconnection between these indices and F10,7 with help of the approximation by the polynomials of second order. The indices we've studied in this paper are: Wolf numbers - W, 530,3 nm coronal line flux - F530, the total solar irradiance - TSI, Mg II UV-index 280 nm core-to-wing ratio, Flare Index - FI and Counts of flares. In the most cases the regressions of these solar indices versus F10,7 are close to linear except the moments of time near to the minimums and maximums of 11-year activity. For the linear regressions we found that the values of correlation coefficients Kcorr(t) for the indices versus F10,7 and W show the cyclic variations with periods approximately equal to the to half length of 11-year cycle - 5,5 years approximately.

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

    Science.gov (United States)

    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.

  17. Extreme Ionospheric Gradients Observed in South Korea during the Last Solar Cycle

    Science.gov (United States)

    Jung, S.; Choi, Y.; Kim, M.; Lee, J.

    2012-12-01

    Ground-Based Augmentation Systems (GBAS) support aircraft precision approach and landing by providing differential corrections for Global Navigation Satellite System (GNSS) pseudorange measurements and integrity information to aviation users within several tens of kilometers of GBAS-equipped airports. During the peak of the last solar cycle, extreme ionospheric gradients as large as 412 mm/km at high elevation and 360 mm/km at low elevation were observed in the United States. For a GBAS user at a 200-foot decision height (DH) for Category I precision approach, a spatial gradient of 412 mm/km could cause a residual range error of 8 meters. To predict the maximum position errors that GBAS users might suffer from these ionospheric threats, an ionospheric anomaly "threat model" for GBAS was developed in the Conterminous U.S (CONUS). The threat model issued to simulate worst-case ionospheric errors and develop mitigation strategies under ionospheric disturbances. Ionospheric conditions should be investigated for all regions where GBAS will be fielded in the future. We presents a method to identify ionospheric anomalies that can pose a potential integrity risk to GBAS users and details the study of extreme ionospheric gradients observed in South Korea during the last solar cycle. GPS dual-frequency code and carrier-phase measurements collected from a total of 74 GPS reference stations in South Korea were processed to observe ionospheric anomalies. Precise ionospheric delay estimates are obtained using the simplified truth processing method and ionospheric gradients are computed using the well-known "station pair method". Ionospheric threats can be modeled as a spatially linear semi-infinite wedge moving with constant speed in mid-latitude regions. A total of 22 dates during the last solar maximum period in 2000 - 2004 were investigated to identify ionospheric anomalies occurred in South Korea. Ten of the dates were the days previously chosen to construct the current

  18. Low-Latitude Coronal Holes at the Minimum of the 23rd Solar Cycle

    CERN Document Server

    Abramenko, V; Linker, J; Mikic, Z; Luhmann, J; Lee, C

    2010-01-01

    Low and mid-latitude coronal holes (CHs) observed on the Sun during the current solar activity minimum (from September 21, 2006, Carrington rotation (CR) 2048, until June 26, 2009 (CR 2084)) were analyzed using {\\it SOHO}/EIT and STEREO-A SECCHI EUVI data. From both the observations and Potential Field Source Surface (PFSS) modeling, we find that the area occupied by CHs inside a belt of $\\pm 40^\\circ$ around the solar equator is larger in the current 2007 solar minimum relative to the similar phase of the previous 1996 solar minimum. The enhanced CH area is related to a recurrent appearance of five persistent CHs, which survived during 7-27 solar rotations. Three of the CHs are of positive magnetic polarity and two are negative. The most long-lived CH was being formed during 2 days and existed for 27 rotations. This CH was associated with fast solar wind at 1 AU of approximately 620$\\pm 40$ km s$^{-1}$. The 3D MHD modeling for this time period shows an open field structure above this CH. We conclude that the...

  19. Properties and Geoeffectiveness of Magnetic Clouds during Solar Cycles 23 and 24

    CERN Document Server

    Gopalswamy, N; Xie, H; Akiyama, S; Mäkelä, P

    2015-01-01

    We report on a study that compares the properties of magnetic clouds (MCs) during the first 73 months of solar cycles 23 and 24 in order to understand the weak geomagnetic activity in cycle 24. We find that the number of MCs did not decline in cycle 24, although the average sunspot number is known to have declined by ~40%. Despite the large number of MCs, their geoeffectiveness in cycle 24 was very low. The average Dst index in the sheath and cloud portions in cycle 24 was -33 nT and -23 nT, compared to -66 nT and -55 nT, respectively in cycle 23. One of the key outcomes of this investigation is that the reduction in the strength of geomagnetic storms as measured by the Dst index is a direct consequence of the reduction in the factor VBz (the product of the MC speed and the out-of-the-ecliptic component of the MC magnetic field). The reduction in MC-to-ambient total pressure in cycle 24 is compensated for by the reduction in the mean MC speed, resulting in the constancy of the dimensionless expansion rate at ...

  20. The Shape of Solar Cycles Described by a Simplified Binary Mixture of Gaussian Functions

    Science.gov (United States)

    Li, F. Y.; Xiang, N. B.; Kong, D. F.; Xie, J. L.

    2017-01-01

    Sunspot cycles usually present a double-peak structure. This work is devoted to using a function to describe the shape of sunspot cycles, including bimodal cycles, and we find that the shape of sunspot cycles can be described by a binary mixture of Gaussian functions with six parameters, two amplitudes, two gradients of curve, and two rising times, and the parameters could be reduced to three. The fitting result of this binary mixture of Gaussian functions is compared with some other functions used previously in the literature, and this function works pretty well, especially at cycle peaks. It is worth mentioning that the function can describe well the shape of those sunspot cycles that show double peaks, and it is superior to the binary mixture of the Laplace functions that was once utilized. The Solar Influences Data Analysis Center, on behalf of the World Data Center, recently issued a new version (version 2) of sunspot number. The characteristics of sunspot cycles are investigated, based on the function description of the new version.

  1. Closed-form expression for the current/ voltage characteristics of pin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Taretto, K.; Rau, U.; Werner, J.H. [Institut fuer Physikalische Elektronik, Pfaffenwaldring 47, 70569, Stuttgart (Germany)

    2003-12-01

    A closed-form expression for the current-voltage relationship of pin diodes and pin solar cells is obtained. The model considers drift and diffusion currents, and assumes a uniform electric field in the intrinsic layer, equal diffusion lengths for electrons and holes and a homogeneous generation rate. We show that both drift and diffusion currents must be taken into account to describe the current over a wide range of applied voltage. The inclusion of both transport mechanisms results in diode ideality factors between 1.8 at low, and 1.2 at high applied voltages. Comparisons of current/voltage characteristics and solar cell output parameters obtained from our model with experimental data of thin-film silicon solar cells show that our model accurately explains the output characteristics of pin solar cells. (orig.)

  2. Statistical Prediction of Solar Particle Event Frequency Based on the Measurements of Recent Solar Cycles for Acute Radiation Risk Analysis

    Science.gov (United States)

    Myung-Hee, Y. Kim; Shaowen, Hu; Cucinotta, Francis A.

    2009-01-01

    Large solar particle events (SPEs) present significant acute radiation risks to the crew members during extra-vehicular activities (EVAs) or in lightly shielded space vehicles for space missions beyond the protection of the Earth's magnetic field. Acute radiation sickness (ARS) can impair performance and result in failure of the mission. Improved forecasting capability and/or early-warning systems and proper shielding solutions are required to stay within NASA's short-term dose limits. Exactly how to make use of observations of SPEs for predicting occurrence and size is a great challenge, because SPE occurrences themselves are random in nature even though the expected frequency of SPEs is strongly influenced by the time position within the solar activity cycle. Therefore, we developed a probabilistic model approach, where a cumulative expected occurrence curve of SPEs for a typical solar cycle was formed from a non-homogeneous Poisson process model fitted to a database of proton fluence measurements of SPEs that occurred during the past 5 solar cycles (19 - 23) and those of large SPEs identified from impulsive nitrate enhancements in polar ice. From the fitted model, the expected frequency of SPEs was estimated at any given proton fluence threshold (Phi(sub E)) with energy (E) >30 MeV during a defined space mission period. Corresponding Phi(sub E) (E=30, 60, and 100 MeV) fluence distributions were simulated with a random draw from a gamma distribution, and applied for SPE ARS risk analysis for a specific mission period. It has been found that the accurate prediction of deep-seated organ doses was more precisely predicted at high energies, Phi(sub 100), than at lower energies such as Phi(sub 30) or Phi(sub 60), because of the high penetration depth of high energy protons. Estimates of ARS are then described for 90th and 95th percentile events for several mission lengths and for several likely organ dose-rates. The ability to accurately measure high energy protons

  3. Ionospheric response to X-class solar flares in the ascending half of the subdued solar cycle 24

    Indian Academy of Sciences (India)

    Rumajyoti Hazarika; Bitap Raj Kalita; Pradip Kumar Bhuyan

    2016-08-01

    The signature of 11 X-class solar flares that occurred during the ascending half of the present subdued solar cycle 24 from 2009 to 2013 on the ionosphere over the low- and mid-latitude station, Dibrugarh (27.5◦N, 95◦E; magnetic latitude 17.6◦N), are examined. Total electron content (TEC) data derived from Global Positioning System satellite transmissions are used to study the effect of the flares on the ionosphere. A nonlinear significant correlation ($R^2$ =0.86) has been observed between EUV enhancement (ΔEUV) and corresponding enhancement in TEC (ΔTEC). This nonlinearity is triggered by a rapid increase in ΔTEC beyond the threshold value ∼1.5 (×1010 ph cm$^{−2} s^{−1})$ in ΔEUV. It is also foundthat this nonlinear relationship between TEC and EUV flux is driven by a similar nonlinear relationship between flare induced enhancement in X-ray and EUV fluxes. The local time of occurrence of the flares determines the magnitude of enhancement in TEC for flares originating from nearly similar longitudeson the solar disc, and hence proximity to the central meridian alone may not play the dominating role. Further, the X-ray peak flux, when corrected for the earth zenith angle effect, did not improve thecorrelation between ΔX-ray and ΔTEC.

  4. Magnetic Helicity of the Global Field in Solar Cycles 23 and 24

    Science.gov (United States)

    Pipin, V. V.; Pevtsov, A. A.

    2014-07-01

    For the first time we reconstruct the magnetic helicity density of the global axisymmetric field of the Sun using the method proposed by Brandenburg et al. and Pipin et al. To determine the components of the vector potential, we apply a gauge which is typically employed in mean-field dynamo models. This allows for a direct comparison of the reconstructed helicity with the predictions from the mean-field dynamo models. We apply this method to two different data sets: the synoptic maps of the line-of-sight magnetic field from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) and vector magnetic field measurements from the Vector Spectromagnetograph (VSM) on the Synoptic Optical Long-term Investigations of the Sun (SOLIS) system. Based on the analysis of the MDI/SOHO data, we find that in solar cycle 23 the global magnetic field had positive (negative) magnetic helicity in the northern (southern) hemisphere. This hemispheric sign asymmetry is opposite to the helicity of the solar active regions, but it is in agreement with the predictions of mean-field dynamo models. The data also suggest that the hemispheric helicity rule may have reversed its sign during the early and late phases of cycle 23. Furthermore, the data indicate an imbalance in magnetic helicity between the northern and southern hemispheres. This imbalance seems to correlate with the total level of activity in each hemisphere in cycle 23. The magnetic helicity for the rising phase of cycle 24 is derived from SOLIS/VSM data, and qualitatively its latitudinal pattern is similar to the pattern derived from SOHO/MDI data for cycle 23.

  5. THE MINIMUM OF SOLAR CYCLE 23: AS DEEP AS IT COULD BE?

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Jaramillo, Andrés; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Senkpeil, Ryan R. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Tlatov, Andrey G. [Kislovodsk Mountain Astronomical Station of the Pulkovo Observatory, Kislovodsk 357700 (Russian Federation); Pevtsov, Alexei A. [National Solar Observatory, Sunspot, NM 88349 (United States); Balmaceda, Laura A. [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina); DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Martens, Petrus C. H., E-mail: munoz@solar.physics.montana.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States)

    2015-05-01

    In this work we introduce a new way of binning sunspot group data with the purpose of better understanding the impact of the solar cycle on sunspot properties and how this defined the characteristics of the extended minimum of cycle 23. Our approach assumes that the statistical properties of sunspots are completely determined by the strength of the underlying large-scale field and have no additional time dependencies. We use the amplitude of the cycle at any given moment (something we refer to as activity level) as a proxy for the strength of this deep-seated magnetic field. We find that the sunspot size distribution is composed of two populations: one population of groups and active regions and a second population of pores and ephemeral regions. When fits are performed at periods of different activity level, only the statistical properties of the former population, the active regions, are found to vary. Finally, we study the relative contribution of each component (small-scale versus large-scale) to solar magnetism. We find that when hemispheres are treated separately, almost every one of the past 12 solar minima reaches a point where the main contribution to magnetism comes from the small-scale component. However, due to asymmetries in cycle phase, this state is very rarely reached by both hemispheres at the same time. From this we infer that even though each hemisphere did reach the magnetic baseline, from a heliospheric point of view the minimum of cycle 23 was not as deep as it could have been.

  6. Electron and proton acceleration during the first ground level enhancement of solar cycle 24

    CERN Document Server

    Li, C; Sun, L P; Miroshnichenko, L I

    2013-01-01

    High-energy particles were recorded by near-Earth spacecraft and ground-based neutron monitors (NMs) on 2012 May 17. This event was the first ground level enhancement (GLE) of solar cycle 24. In this study, we try to identify the acceleration source(s) of solar energetic particles by combining in situ particle measurements from the WIND/3DP, GOES 13, and solar cosmic rays registered by several NMs, as well as remote-sensing solar observations from SDO/AIA, SOHO/LASCO, and RHESSI. We derive the interplanetary magnetic field (IMF) path length (1.25 +/- 0.05 AU) and solar particle release time (01:29 +/- 00:01 UT) of the first arriving electrons by using their velocity dispersion and taking into account contamination effects. We found that the electron impulsive injection phase, indicated by the dramatic change in the spectral index, is consistent with flare non-thermal emission and type III radio bursts. Based on the potential field source surface concept, modeling of the open-field lines rooted in the active r...

  7. Towards a better representation of the solar cycle in general circulation models

    Directory of Open Access Journals (Sweden)

    K. M. Nissen

    2007-10-01

    Full Text Available We introduce the improved Freie Universität Berlin (FUB high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB. Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction of the solar SW heating rate signal by about 20%.

    The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal.

    Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60–70 km indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account.

    The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy.

  8. Towards a better representation of the solar cycle in general circulation models

    Science.gov (United States)

    Nissen, K. M.; Matthes, K.; Langematz, U.; Mayer, B.

    2007-10-01

    We introduce the improved Freie Universität Berlin (FUB) high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction) of the solar SW heating rate signal by about 20%. The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal. Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60-70 km) indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

  9. The energy spectrum of Forbush decreases during the growth phase of solar cycle 24

    Science.gov (United States)

    Grigoryev, V. G.; Starodubtsev, S. A.; Isakov, D. D.

    2014-05-01

    The Forbush decrease energy spectrum, observed during the growth phase of cycle 24 in 2010-2012, was studied based on the measurements performed with the Kuzmin cosmic ray spectrograph. The data of the 24-NM-64 neutron monitor and muon telescopes, installed at water equivalent levels of 0, 7, 20, and 40 m, was used. The performed analysis indicated that a softer energy spectrum was observed during the growth phase of cycle 24 than during the previous cycle (cycle 23). The conclusion was been drawn that a more turbulent magnetic field with the predominant diffusion mechanism in the formation of the Forbush decreases in the cosmic ray intensity exists in the current cycle (cycle 24).

  10. Current challenges in organic photovoltaic solar energy conversion.

    Science.gov (United States)

    Schlenker, Cody W; Thompson, Mark E

    2012-01-01

    Over the last 10 years, significant interest in utilizing conjugated organic molecules for solid-state solar to electric conversion has produced rapid improvement in device efficiencies. Organic photovoltaic (OPV) devices are attractive for their compatibility with low-cost processing techniques and thin-film applicability to flexible and conformal applications. However, many of the processes that lead to power losses in these systems still remain poorly understood, posing a significant challenge for the future efficiency improvements required to make these devices an attractive solar technology. While semiconductor band models have been employed to describe OPV operation, a more appropriate molecular picture of the pertinent processes is beginning to emerge. This chapter presents mechanisms of OPV device operation, based on the bound molecular nature of the involved transient species. With the intention to underscore the importance of considering both thermodynamic and kinetic factors, recent progress in elucidating molecular characteristics that dictate photovoltage losses in heterojunction organic photovoltaics is also discussed.

  11. A few perspectives of solar physics research in China - current status and future

    Science.gov (United States)

    Wang, Jingxiu; Ding, Mingde; Ji, Haisheng; Deng, Yuanyong; Liu, Yu; Liu, Zhong; Qu, Zhongquan; Wang, Huaning; Xia, Lidong; Yan, Yihua

    2016-07-01

    Solar physics research as an important discipline in astrophysics in China aims at improving the understanding of origin and variation of solar magnetic field and magnetic activity, and founding the basis for forecast of disastrous space weather. The current review is focused on the solar physics research in China in recent three years. Highlights in scientific research in solar magnetism, magnetic activity, coronal plasma, and space weather forecast are briefly summarized. Key advances in instrument development are reported in some necessary details. Future tendency and working direction are considered and discussed.

  12. How can we understand the global distribution of the solar cycle signal on the Earth's surface?

    Science.gov (United States)

    Kodera, Kunihiko; Thiéblemont, Rémi; Yukimoto, Seiji; Matthes, Katja

    2016-10-01

    To understand solar cycle signals on the Earth's surface and identify the physical mechanisms responsible, surface temperature variations from observations as well as climate model data are analysed to characterize their spatial structure. The solar signal in the annual mean surface temperature is characterized by (i) mid-latitude warming and (ii) no overall tropical warming. The mid-latitude warming during solar maxima in both hemispheres is associated with a downward penetration of zonal mean zonal wind anomalies from the upper stratosphere during late winter. During the Northern Hemisphere winter this is manifested by a modulation of the polar-night jet, whereas in the Southern Hemisphere, the upper stratospheric subtropical jet plays the major role. Warming signals are particularly apparent over the Eurasian continent and ocean frontal zones, including a previously reported lagged response over the North Atlantic. In the tropics, local warming occurs over the Indian and central Pacific oceans during high solar activity. However, this warming is counterbalanced by cooling over the cold tongue sectors in the southeastern Pacific and the South Atlantic, and results in a very weak zonally averaged tropical mean signal. The cooling in the ocean basins is associated with stronger cross-equatorial winds resulting from a northward shift of the ascending branch of the Hadley circulation during solar maxima. To understand the complex processes involved in the solar signal transfer, results of an idealized middle atmosphere-ocean coupled model experiment on the impact of stratospheric zonal wind changes are compared with solar signals in observations. Model integration of 100 years of strong or weak stratospheric westerly jet condition in winter may exaggerate long-term ocean feedback. However, the role of ocean in the solar influence on the Earth's surface can be better seen. Although the momentum forcing differs from that of solar radiative forcing, the model results

  13. On the enhanced coronal mass ejection detection rate since the solar cycle 23 polar field reversal

    CERN Document Server

    Petrie, Gordon

    2015-01-01

    Coronal mass ejections (CMEs) with angular width $> 30^{\\circ}$ have been observed to occur at a higher rate during solar cycle 24 compared to cycle 23, per sunspot number. This result is supported by data from three independent databases constructed using Large Angle and Spectrometric Coronagraph Experiment (LASCO) coronagraph images, two employing automated detection techniques and one compiled manually by human observers. According to the two databases that cover a larger field of view, the enhanced CME rate actually began shortly after the cycle 23 polar field reversal, in 2004, when the polar fields returned with a 40\\% reduction in strength and interplanetary radial magnetic field became $\\approx 30\\%$ weaker. This result is consistent with the link between anomalous CME expansion and heliospheric total pressure decrease recently reported by Gopalswamy et al.

  14. Solar cycle dependent characteristics of the equatorial blanketing Es layers and associated irregularities

    Directory of Open Access Journals (Sweden)

    S. Ravindran

    2006-11-01

    Full Text Available The occurrence of blanketing type Es (Esb layers and associated E-region irregularities over the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip ~0.5° during the summer solstitial months of May, June, July and August has been investigated in detail for the period 1986–2000 to bring out the variabilities in their characteristics with the solar cycle changes. The study has been made using the ionosonde and magnetometer data of Trivandrum from 1986–2000 along with the available data from the 54.95 MHz VHF backscatter radar at Trivandrum for the period 1995–2000. The appearance of blanketing Es layers during these months is observed to be mostly in association with the occurrence of afternoon Counter Electrojet (CEJ events. The physical process leading to the occurrence of a CEJ event is mainly controlled by the nature of the prevailing electro dynamical/neutral dynamical conditions before the event. Hence it is natural that the Esb layer characteristics like the frequency of occurrence, onset time, intensity, nature of gradients in its top and bottom sides etc are also affected by the nature of the background electro dynamical /neutral dynamical processes which in turn are strongly controlled by the solar activity changes. The occurrence of Esb layers during the solstitial months is found to show very strong solar activity dependence with the occurrence frequency being very large during the solar minimum years and very low during solar maximum years. The intensity of the VHF radar backscattered signals from the Esb irregularities is observed to be controlled by the relative roles of the direction and magnitude of the prevailing vertical polarization electric field and the vertical electron density gradient of the prevailing Esb layer depending on the phase of the solar cycle. The gradient of the Esb layer shows a more dominant role in the generation of gradient instabilities during solar minimum periods while it is the

  15. A proposed paradigm for solar cycle dynamics mediated via turbulent pumping of magnetic flux in Babcock-Leighton type solar dynamos

    CERN Document Server

    Hazra, Soumitra

    2016-01-01

    At present, Babcock-Leighton flux transport solar dynamo models appear as the most promising model for explaining diverse observational aspects of the sunspot cycle. The success of these flux transport dynamo models is largely dependent upon a single-cell meridional circulation with a deep equatorward component at the base of the Sun's convection zone. However, recent observations suggest that the meridional flow may in fact be very shallow (confined to the top 10 % of the Sun) and more complex than previously thought. Taken together these observations raise serious concerns on the validity of the flux transport paradigm. By accounting for the turbulent pumping of magnetic flux as evidenced in magnetohydrodynamic simulations of solar convection, we demonstrate that flux transport dynamo models can generate solar-like magnetic cycles even if the meridional flow is shallow. Solar-like periodic reversals is recovered even when meridional circulation is altogether absent, however, in this case the solar surface m...

  16. The Thermal Properties of Solar Flares Over Three Solar Cycles Using GOES X-ray Observations

    CERN Document Server

    Ryan, Daniel F; Gallagher, Peter T; Dennis, Brian R; Tolbert, A Kim; Schwartz, Richard A; Young, C Alex

    2012-01-01

    Solar flare X-ray emission results from rapidly increasing temperatures and emission measures in flaring active region loops. To date, observations from the X-Ray Sensor (XRS) onboard the Geostationary Operational Environmental Satellite (GOES) have been used to derive these properties, but have been limited by a number of factors, including the lack of a consistent background subtraction method capable of being automatically applied to large numbers of flares. In this paper, we describe an automated temperature and emission measure-based background subtraction method (TEBBS), which builds on the methods of Bornmann (1990). Our algorithm ensures that the derived temperature is always greater than the instrumental limit and the pre-flare background temperature, and that the temperature and emission measure are increasing during the flare rise phase. Additionally, TEBBS utilizes the improved estimates of GOES temperatures and emission measures from White et al. (2005). TEBBS was successfully applied to over 50,...

  17. Solar cycle modulation of the ENSO impact on the winter climate of East Asia

    Science.gov (United States)

    Zhou, Qun; Chen, Wen; Zhou, Wen

    2013-06-01

    This study examines how the East Asian winter climate response to the El Niño-Southern Oscillation (ENSO) varies with the 11-year solar cycle. The results indicate that the ENSO and East Asian climate relationship is robust and significant during winters with low solar (LS) activity, with evident warming in the lower troposphere over East Asia, which can be closely linked to the decreased pressure gradient between the cold Eurasian continent and the warm Pacific. Moreover, during the LS and El Niño winters, there is a typical rainfall response in Southeast Asia, with wet conditions over South China and dry conditions over the Philippines, Borneo, Celebes, and Sulawesi, which can be explained by the anticyclone over the western North Pacific (WNP). However, during high solar activity winters, both the surface temperature and rainfall anomalies are much less closely associated with the ENSO. The possible mechanism for this solar modulation of the ENSO-related East Asian climate anomalies may be the change in the tropospheric circulation with the ENSO in both tropical and extratropical regions. Particularly, in the LS cases, an anomalous WNP anticyclone is intensified and a noticeable cyclone occupies northern Northeast Asia, resulting from the changing location and strength of the large-scale Walker circulation induced by the more pronounced sea surface temperature anomalies associated with the ENSO. Further investigation with long historic data confirms that the relationship between the ENSO and the East Asian winter climate anomalies depends on the phases of 11 year solar cycle, with enhanced East Asian climate variation during the LS winters.

  18. Current progress and future perspectives for organic/inorganic perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Pablo P. Boix

    2014-01-01

    Full Text Available The recent emergence of efficient solar cells based on organic/inorganic lead halide perovskite absorbers promises to transform the fields of dye-sensitized, organic, and thin film solar cells. Solution processed photovoltaics incorporating perovskite absorbers have achieved efficiencies of 15% [1] in solid-state device configurations, superseding liquid dye sensitized solar cell (DSC, evaporated and tandem organic solar cells, as well as various thin film photovoltaics; thus establishing perovskite solar cells as a robust candidate for commercialization. Since the first reports in late 2012, interest has soared in the innovative device structures as well as new materials, promising further improvements. However, identifying the basic working mechanisms, which are still being debated, will be crucial to design the optimum device configuration and maximize solar cell efficiencies. Here we distill the current state-of-the-art and highlight the guidelines to ascertain the scientific challenges as well as the requisites to make this technology market-viable.

  19. Environmental life cycle assessment of roof-integrated flexible amorphous silicon/nanocrystalline silicon solar cell laminate

    NARCIS (Netherlands)

    N.J. Mohr; A. Meijer; M.A.J. Huijbregts; L. Reijnders

    2013-01-01

    This paper presents an environmental life cycle assessment of a roof-integrated flexible solar cell laminate with tandem solar cells composed of amorphous silicon/nanocrystalline silicon (a-Si/nc-Si). The a-Si/nc-Si cells are considered to have 10% conversion efficiency. Their expected service life

  20. Can the solar cycle and climate synchronize the snowshoe hare cycle in Canada? Evidence from tree rings and ice cores.

    Science.gov (United States)

    Sinclair, A R; Gosline, J M; Holdsworth, G; Krebs, C J; Boutin, S; Smith, J N; Boonstra, R; Dale, M

    1993-02-01

    Dark marks in the rings of white spruce less than 50 yr old in Yukon, Canada, are correlated with the number of stems browsed by snowshoe hares. The frequency of these marks is positively correlated with the density of hares in the same region. The frequency of marks in trees germinating between 1751 and 1983 is positively correlated with the hare fur records of the Hudson Bay Company. Both tree marks and hare numbers are correlated with sunspot numbers, and there is a 10-yr periodicity in the correlograms. Phase analysis shows that tree marks and sunspot numbers have periods of nearly constant phase difference during the years 1751-1787, 1838-1870, and 1948 to the present, and these periods coincide with those of high sunspot maxima. The nearly constant phase relations between the annual net snow accumulation on Mount Logan and (1) tree mark ratios, (2) hare fur records before about 1895, and (3) sunspot number during periods of high amplitude in the cycles suggest there is a solar cycle-climate-hare population and tree mark link. We suggest four ways of testing this hypothesis.

  1. Numerical study on short-circuit current of single layer organic solar cells with Schottkey contacts

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The influence of the cathode work function,carriers mobilities and temperature on the short-circuit current of single layer organic solar cells with Schottkey contacts was numerically studied,and the quantitative dependences of the short-circuit current on these quantities were obtained.The results provide the theoretical foundation for experimental study of single layer organic solar cells with Schottkey contacts.

  2. Simulations of airglow variations induced by the CO2 increase and solar cycle variation from 1980 to 1991

    Science.gov (United States)

    Huang, Tai-Yin

    2016-09-01

    Airglow intensity and Volume Emission Rate (VER) variations induced by the increase of CO2 gas concentration and F10.7 variation (used as a proxy for the 11-year solar cycle variation) were investigated for the period from 1980 to 1991, encompassing a full solar cycle. Two airglow models are used to simulate the induced variations of O(1S) greenline, O2(0,1) atmospheric band , and OH(8,3) airglow for this study. The results show that both the airglow intensities and peak VERs correlate positively with the F10.7 solar cycle variation and display a small linear trend due to the increase of CO2 gas concentration. The solar-cycle induced airglow intensity variations show that O(1S) greenline has the largest variation (~26%) followed by the O2(0,1) atmospheric band (~23%) and then OH(8,3) airglow (~8%) over the 11 year timespan. The magnitudes of the induced airglow intensity variations by the increase of CO2 gas concentration are about an order of magnitude smaller than those by the F10.7 solar cycle variation. In general, the F10.7 solar cycle variation and CO2 increase do not seem to systematically alter the VER peak altitude of the airglow emissions, though the OH(8,3) VER peak altitude moves up slightly during the years when the F10.7 value falls under 100 SFU.

  3. Solar terrestrial relationships related to thunderstorms and BUV dark current and ozone data

    Science.gov (United States)

    Herman, J. R.

    1980-01-01

    Solar terrestrial interactions as they affect Nimbus 4 BUV dark current and possibly affect thunderstorm occurrence are investigated. A solar wind index is calculated for 1970 to 1971. Dark current enhancements appear to be associated in some way with solar proton events and the solar wind index, but additional investigations by GSFC are required before conclusions can be drawn. Superposed epoch analysis of an index of North American thunderstorm occurrence reveals a discernible increase in the index magnitude on days 1 and 2 following solar proton events. There appears to be little or no 27 day recurrence tendency in thunderstorm occurrence frequency and no association with vorticity area index on a day to day basis.

  4. Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

    Science.gov (United States)

    Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

    1996-01-01

    This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

  5. Exergetic Analysis of a Novel Solar Cooling System for Combined Cycle Power Plants

    Directory of Open Access Journals (Sweden)

    Francesco Calise

    2016-09-01

    Full Text Available This paper presents a detailed exergetic analysis of a novel high-temperature Solar Assisted Combined Cycle (SACC power plant. The system includes a solar field consisting of innovative high-temperature flat plate evacuated solar thermal collectors, a double stage LiBr-H2O absorption chiller, pumps, heat exchangers, storage tanks, mixers, diverters, controllers and a simple single-pressure Combined Cycle (CC power plant. Here, a high temperature solar cooling system is coupled with a conventional combined cycle, in order to pre-cool gas turbine inlet air in order to enhance system efficiency and electrical capacity. In this paper, the system is analyzed from an exergetic point of view, on the basis of an energy-economic model presented in a recent work, where the obtained main results show that SACC exhibits a higher electrical production and efficiency with respect to the conventional CC. The system performance is evaluated by a dynamic simulation, where detailed simulation models are implemented for all the components included in the system. In addition, for all the components and for the system as whole, energy and exergy balances are implemented in order to calculate the magnitude of the irreversibilities within the system. In fact, exergy analysis is used in order to assess: exergy destructions and exergetic efficiencies. Such parameters are used in order to evaluate the magnitude of the irreversibilities in the system and to identify the sources of such irreversibilities. Exergetic efficiencies and exergy destructions are dynamically calculated for the 1-year operation of the system. Similarly, exergetic results are also integrated on weekly and yearly bases in order to evaluate the corresponding irreversibilities. The results showed that the components of the Joule cycle (combustor, turbine and compressor are the major sources of irreversibilities. System overall exergetic efficiency was around 48%. Average weekly solar collector

  6. Azimuthally asymmetric ring current as a function of Dst and solar wind conditions

    Directory of Open Access Journals (Sweden)

    A. A. Ostapenko

    2004-09-01

    Full Text Available Based on magnetic data, spatial distribution of the westward ring current flowing at |z|<3 RE has been found under five levels of Dst, five levels of the interplanetary magnetic field (IMF z component, and five levels of the solar wind dynamic pressure Psw. The maximum of the current is located near midnight at distances 5 to 7 RE. The magnitude of the nightside and dayside parts of the westward current at distances from 4 to 9 RE can be approximated as Inight=1.75-0.041 Dst, Inoon=0.22-0.013 Dst, where the current is in MA. The relation of the nightside current to the solar wind parameters can be expressed as Inight=1.45-0.20 Bs IMF + 0.32 Psw, where BsIMF is the IMF southward component. The dayside ring current poorly correlates with the solar wind parameters.

  7. Polar Network Index as a magnetic proxy for the solar cycle studies

    CERN Document Server

    Priyal, Muthu; Karak, Bidya Binay; Munoz-Jaramillo, Andres; Ravindra, B; Choudhuri, Arnab Rai; Singh, Jagdev

    2014-01-01

    The Sun has a polar magnetic field which oscillates with the 11 year sunspot cycle. This polar magnetic field is an important component of the dynamo process which is operating in the solar convection zone and produces the sunspot cycle. We have systematic direct measurements of the Sun's polar magnetic field only from about mid 1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca K spectroheliograms taken in Kodaikanal Solar Observatory during 1904 - 2007 have now been digitized with the 4k x 4k CCD and have higher resolution (0.86 arcsec) than the other available historical datasets. From these Ca-K spectroheliograms, we have developed a completely new proxy (Polar Network Index, PNI) for the Sun's polar magnetic field. We calculate the PNI from the digitized images using an automated algorithm and calibrate our measured PNI against the polar field as measured by the Wilcox Solar Observatory for the period of 1976 - 1990. This calibration allows us ...