Science.gov

Sample records for 11-yr solar cycle

  1. The climate response to the 11-yr solar cycle in the CMIP5 historical simulations

    NASA Astrophysics Data System (ADS)

    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.

  2. Non-linear alignment of El Niño to the 11-yr solar cycle

    NASA Astrophysics Data System (ADS)

    White, Warren B.; Liu, Zhengyu

    2008-10-01

    El Nino/La Nina episodes represent warm/cool phases of 2- to 7-yr period El Nino-Southern Oscillation (ENSO) in the tropical Pacific ocean-atmosphere system. Modeling studies find ENSO self-excited or driven by ambient noise. Here we find most El Nino and La Nina episodes from 1900-2005 grouped into non-commuting pairs that repeat every ~11 yrs, aligned with rising and falling transition phases of the ~11-yr period quasi-decadal oscillation (QDO). These alignments arise from non-linear phase locking of 3rd and 5th harmonics near 3.6- and 2.2-yr to the 1st harmonic near 11-yr period. Here we find these alignments replicated in both coupled general circulation model and conceptual model driven by 11-yr solar forcing, wherein the solar-forced 1st harmonic initiates a non-linear cascade of higher odd harmonics that are phase-locked with the same alignments as observed. These solar-forced 3rd and 5th harmonics explain ~52% of inter-annual variance in the Nino-3 temperature index from 1900-2005.

  3. On the Response of Halogen Occultation Experiment (HALOE) Stratospheric Oxone and Temperature to the 11-yr Solar Cycle Forcing

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.

    2008-01-01

    Results are presented on responses in 14-yr time series of stratospheric ozone and temperature from the Halogen Occultation Experiment (HALOE) of the Upper Atmosphere Research Satellite (UARS) to a solar cycle (SC-like) variation. The ozone time series are for ten, 20-degree wide, latitude bins from 45S to 45N and for thirteen "half-Umkehr" layers of about 2.5 km thickness and extending from 63 hPa to 0.7 hPa. The temperature time series analyses were restricted to pressure levels in the range of 2 hPa to 0.7 hPa. Multiple linear regression (MLR) techniques were applied to each of the 130 time series of zonally-averaged, sunrise plus sunset ozone points over that latitude/pressure domain. A simple, 11-yr periodic term and a linear trend term were added to the final MLR models after their seasonal and interannual terms had been determined. Where the amplitudes of the 11-yr terms were significant, they were in-phase with those of the more standard proxies for the solar uv-flux. The max minus min response for ozone is of order 2 to 3% from about 2 to 5 hPa and for the latitudes of 45S to 45N. There is also a significant max minus min response of order 1 K for temperature between 15S and 15N and from 2 to 0.7 hPa. The associated linear trends for ozone are near zero in the upper stratosphere. Negative ozone trends of 4 to 6%/decade were found at 10 to 20 hPa across the low to middle latitudes of both hemispheres. It is concluded that the analyzed responses from the HALOE data are of good quality and can be used to evaluate the responses of climate/chemistry models to a solar cycle forcing.

  4. Estimating the solar meridional flow and predicting the 11-yr cycle using advanced variational data assimilation techniques

    NASA Astrophysics Data System (ADS)

    Hung, C. P.; Brun, S.; Fournier, A.; Jouve, L.; Talagrand, O.

    2016-12-01

    We show how a mean field solar dynamo model can be used in conjunction with magnetic observations of the Sun in order to estimate the large-scale meridional circulation and further extended to predict the 11-yr cycle. Our innovative approach rests on variational data assimilation, where the difference between predictions and observations (measured by an objective function) is iteratively minimized by an optimization algorithm. The algorithm seeks a meridional flow which best accounts for the data and the integration of an adjoint dynamo model. Closed-loop (also known as twin) experiments using synthetic data demonstrate the validity and accuracy of this technique, for a variety of meridional flow configurations, ranging from unicellular and equatorially symmetric to multicellular and equatorially asymmetric. We find that the method is robust, leading in most cases to a recovery of the true meridional flow within an error of 1%. We also show that our technique is capable of reconstructing a stochastic, time varying meridional flow and the initial magnetic field at the convection zone within the assimilation window, by ingesting synthetic solar magnetic proxies. These encouraging results are a first step towards using this technique to i) better constrain the physical processes occurring inside the Sun and ii) better predict solar activity on decadal time scales, and with our technique we are currently analyzing the observations of the last 3 solar cycles from Wilcox Solar Observatory to estimate the meridional flow.

  5. Total ozone and the 11-yr sunspot cycle

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; van Loon, H.

    1997-01-01

    The correlations between the total column ozone observed by TOMS and the 11-yr sunspot cycle are lowest in the equatorial region, where ozone is produced, and in the subpolar regions, where the largest amounts are found. In the annual mean the highest, statistically significant, correlations lie between the 5° and 30° parallels of latitude in either hemisphere-between the area of production and the areas of plenty. This position of the largest correlations suggests that the association between the Sun and the ozone is not a direct, radiative one, but that it is due to solar induced changes in the transport of ozone, that is, to changes in the atmospheric circulation. The highest tropical-subtropical correlations move with the Sun from summer hemisphere to summer hemisphere. The subtropical geopotential heights in the ozone layer are higher in the peaks than in the valleys of the 11-yr sunspot cycle. It is probable that the higher subtropical geopotentials in solar maxima depress the poleward transport of ozone through the subtropics and therefore create an abundance of ozone in the tropics relative to the solar minima. These results are based on a 15-yr series of ozone observations and may thus not necessarily be representative of a longer period.

  6. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  7. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    The 11-yr solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOSCCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 - 3 times larger than the simulation using the NRL SSI. The GEOSCCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. This is important in that it means that chemistry-transport models should simulate the solar cycle in ozone well, while general circulation models without coupled chemistry will underestimate the temperature response to the solar cycle significantly in the middle atmosphere. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally

  8. Plasma flows in the heliosheath along the Voyager 1 and 2 trajectories due to effects of the 11 yr solar cycle

    SciTech Connect

    Provornikova, E.; Opher, M.; Izmodenov, V. V.; Richardson, J. D.; Toth, G. E-mail: mopher@bu.edu E-mail: jdr@space.mit.edu

    2014-10-10

    We investigate the role of the 11 yr solar cycle variations in the solar wind (SW) parameters on the flows in the heliosheath using a new three-dimensional time-dependent model of the interaction between the SW and the interstellar medium. For boundary conditions in the model we use realistic time and the latitudinal dependence of the SW parameters obtained from SOHO/SWAN and interplanetary scintillation data for the last two solar cycles (1990-2011). This data set generally agrees with the in situ Ulysses measurements from 1991 to 2009. For the first ∼30 AU of the heliosheath the time-dependent model predicts constant radial flow speeds at Voyager 2 (V2), which is consistent with observations and different from the steady models that show a radial speed decrease of 30%. The model shows that V2 was immersed in SW with speeds of 500-550 km s{sup –1} upstream of the termination shock before 2009 and in wind with upstream speeds of 450-500 km s{sup –1} after 2009. The model also predicts that the radial velocity along the Voyager 1 (V1) trajectory is constant across the heliosheath, contrary to observations. This difference in observations implies that additional effects may be responsible for the different flows at V1 and V2. The model predicts meridional flows (VN) higher than those observed because of the strong bluntness of the heliosphere shape in the N direction in the model. The modeled tangential velocity component (VT) at V2 is smaller than observed. Both VN and VT essentially depend on the shape of the heliopause.

  9. Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Richardson, I. G.; Ling, A. G.

    2011-01-01

    In the current paradigm for the modulation of galactic cosmic rays (GCRs), diffusion is taken to be the dominant process during solar maxima while drift dominates at minima. Observations during the recent solar minimum challenge the pre-eminence of drift: at such times. In 2009, the approx.2 GV GCR intensity measured by the Newark neutron monitor increased by approx.5% relative to its maximum value two cycles earlier even though the average tilt angle in 2009 was slightly larger than that in 1986 (approx.20deg vs. approx.14deg), while solar wind B was significantly lower (approx.3.9 nT vs. approx.5.4 nT). A decomposition of the solar wind into high-speed streams, slow solar wind, and coronal mass ejections (CMEs; including postshock flows) reveals that the Sun transmits its message of changing magnetic field (diffusion coefficient) to the heliosphere primarily through CMEs at solar maximum and high-speed streams at solar minimum. Long-term reconstructions of solar wind B are in general agreement for the approx. 1900-present interval and can be used to reliably estimate GCR intensity over this period. For earlier epochs, however, a recent Be-10-based reconstruction covering the past approx. 10(exp 4) years shows nine abrupt and relatively short-lived drops of B to < or approx.= 0 nT, with the first of these corresponding to the Sporer minimum. Such dips are at variance with the recent suggestion that B has a minimum or floor value of approx.2.8 nT. A floor in solar wind B implies a ceiling in the GCR intensity (a permanent modulation of the local interstellar spectrum) at a given energy/rigidity. The 30-40% increase in the intensity of 2.5 GV electrons observed by Ulysses during the recent solar minimum raises an interesting paradox that will need to be resolved.

  10. Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Richardson, I. G.; Ling, A. G.

    2013-06-01

    In the current paradigm for the modulation of galactic cosmic rays (GCRs), diffusion is taken to be the dominant process during solar maxima while drift dominates at minima. Observations during the recent solar minimum challenge the pre-eminence of drift at such times. In 2009, the ˜2 GV GCR intensity measured by the Newark neutron monitor increased by ˜5% relative to its maximum value two cycles earlier even though the average tilt angle in 2009 was slightly larger than that in 1986 (˜20° vs. ˜14°), while solar wind B was significantly lower (˜3.9 nT vs. ˜5.4 nT). A decomposition of the solar wind into high-speed streams, slow solar wind, and coronal mass ejections (CMEs; including post-shock flows) reveals that the Sun transmits its message of changing magnetic field (diffusion coefficient) to the heliosphere primarily through CMEs at solar maximum and high-speed streams at solar minimum. Long-term reconstructions of solar wind B are in general agreement for the ˜1900-present interval and can be used to reliably estimate GCR intensity over this period. For earlier epochs, however, a recent 10Be-based reconstruction covering the past ˜104 years shows nine abrupt and relatively short-lived drops of B to ≲0 nT, with the first of these corresponding to the Spörer minimum. Such dips are at variance with the recent suggestion that B has a minimum or floor value of ˜2.8 nT. A floor in solar wind B implies a ceiling in the GCR intensity (a permanent modulation of the local interstellar spectrum) at a given energy/rigidity. The 30-40% increase in the intensity of 2.5 GV electrons observed by Ulysses during the recent solar minimum raises an interesting paradox that will need to be resolved.

  11. Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation (PostPrint)

    DTIC Science & Technology

    2012-03-06

    largely reproduce the observed GCR intensity for the past ∼35 years. The failure to do so during cycle 20 appears to be a relatively rare occurrence. Fig... Terr . Phys. 70, 207 (2008) M.S. Potgieter, Adv. Space Res. 46, 402 (2010) M.S. Potgieter, J.A. Le Roux, Astrophys. J. 423, 817 (1994) M.S. Potgieter

  12. CMEs, the Tail of the Solar Wind Magnetic Field Distribution, and 11-yr Cosmic Ray Modulation at 1 AU. Revised

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Ling, A. G.; Richardson, I. G.

    2003-01-01

    Using a recent classification of the solar wind at 1 AU into its principal components (slow solar wind, high-speed streams, and coronal mass ejections (CMEs) for 1972-2000, we show that the monthly-averaged galactic cosmic ray intensity is anti-correlated with the percentage of time that the Earth is imbedded in CME flows. We suggest that this correlation results primarily from a CME related change in the tail of the distribution function of hourly-averaged values of the solar wind magnetic field (B) between solar minimum and solar maximum. The number of high-B (square proper subset 10 nT) values increases by a factor of approx. 3 from minimum to maximum (from 5% of all hours to 17%), with about two-thirds of this increase due to CMEs. On an hour-to-hour basis, average changes of cosmic ray intensity at Earth become negative for solar wind magnetic field values square proper subset 10 nT.

  13. The Solar Cycle

    NASA Astrophysics Data System (ADS)

    Hathaway, David H.

    2015-12-01

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

  14. On Solar Flares and Cycle 23

    NASA Astrophysics Data System (ADS)

    Kossobokov, V. G.; Le Mouel, J.; Courtillot, V.

    2011-12-01

    The anomalous character of solar cycle 23 has been pointed out. It is proposed that the solar dynamo is undergoing a transition from a state of "grand maximum" to one of "regular oscillations". In this study, we analyze the time distribution of the number and energy of solar flares, and the duration of intervals between them, from cycle 21 to 23. We consider 32355 flares of class C2 and larger (C2+) from the GOES catalogue. Daily values of X-ray flux (wavelengths 1-8Å) have been computed by summing the energy proxies of the events. The series of daily numbers of C2+ solar flares are strongly correlated to their daily energy flux. The long duration of cycle 23 (~13 years), the long interval with no C2+ flare between the end of cycle 23 and the start of cycle 24 (466 days) are remarkable compared to the two earlier cycles. Amplitudes of extreme flares increase when mean flux decreases. We have calculated running averages of energy flux over intervals going from 7 to 365 days: the singular shape of cycle 23 is increasingly striking with increasing interval: the first ~70% of the cycle display (in logarithmic scale) linearly rising maxima, whereas minima are aligned along a descending slope for the latter part of the cycle. Energy flux oscillates between these and takes the shape of a bifurcation, starting near 2002. Durations of inter-event intervals between successive C2+ flares undergo quasi-periodic (~11yr) oscillations between two distinct states, which we call "active" and "quiet", with sharp onset and termination. The ratio of time spent in the active vs quiet states ranges from 1.8 to 1.4 for cycles 21 to 23, cycle 23 having the longest quiet period. It has been proposed that anomalous cycle 23 resembles cycle 4, which was followed by reduced cycles 5 and 6 at the time of the Dalton-minimum in solar activity, often associated with a cooler global climate. It will be interesting to monitor the evolution of solar flares in cycle 24, in order to further our

  15. THE BIMODAL STRUCTURE OF THE SOLAR CYCLE

    SciTech Connect

    Du, Z. L.

    2015-05-01

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

  16. Solar Cycle Prediction

    NASA Technical Reports Server (NTRS)

    Pesnell, William Dean

    2011-01-01

    Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan your next vacation. 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. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. I will describe the current state of solar cycle predictions and anticipate how those predictions could be made more accurate in the future.

  17. The Solar Cycle.

    PubMed

    Hathaway, David H

    The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24. Supplementary material is available for this article at 10.1007/lrsp-2015-4.

  18. Solar Cycle Predictions

    NASA Technical Reports Server (NTRS)

    Pesnell, William Dean

    2012-01-01

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

  19. Solar Cycle Prediction.

    PubMed

    Petrovay, Kristóf

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

  20. Understanding Solar Cycle Variability

    NASA Astrophysics Data System (ADS)

    Cameron, R. H.; Schüssler, M.

    2017-07-01

    The level of solar magnetic activity, as exemplified by the number of sunspots and by energetic events in the corona, varies on a wide range of timescales. Most prominent is the 11-year solar cycle, which is significantly modulated on longer timescales. Drawing from dynamo theory, together with the empirical results of past solar activity and similar phenomena for solar-like stars, we show that the variability of the solar cycle can be essentially understood in terms of a weakly nonlinear limit cycle affected by random noise. In contrast to ad hoc “toy models” for the solar cycle, this leads to a generic normal-form model, whose parameters are all constrained by observations. The model reproduces the characteristics of the variable solar activity on timescales between decades and millennia, including the occurrence and statistics of extended periods of very low activity (grand minima). Comparison with results obtained with a Babcock-Leighton-type dynamo model confirm the validity of the normal-mode approach.

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

    SciTech Connect

    Lean, J. )

    1990-11-01

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

  2. Solar 22 years cycle

    NASA Astrophysics Data System (ADS)

    Kotov, Valery A.; Sanchez, Francis M.

    2017-01-01

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

  3. Solar cycle variations in the solar wind

    NASA Technical Reports Server (NTRS)

    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.

  4. Deciphering solar magnetic activity. I. On the relationship between the sunspot cycle and the evolution of small magnetic features

    SciTech Connect

    McIntosh, Scott W.; Wang, Xin; Markel, Robert S.; Thompson, Michael J.; Leamon, Robert J.; Malanushenko, Anna V.; Davey, Alisdair R.; Howe, Rachel; Krista, Larisza D.; Cirtain, Jonathan W.; Gurman, Joseph B.; Pesnell, William D.

    2014-09-01

    Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ∼22 yr. The principal variation of sunspots, an ∼11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

  5. Forecast of solar cycle 25

    NASA Astrophysics Data System (ADS)

    Krasotkin, Serge; Shmorgilov, Feodor

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

  6. Solar Cycle Predictions (Invited Review)

    NASA Astrophysics Data System (ADS)

    Pesnell, W. Dean

    2012-11-01

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

  7. Solar Cycle #24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth; Pesnell, W. Dean

    2007-01-01

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

  8. Solar Cycle #24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean; Schatten, Kenneth

    2007-01-01

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

  9. Solar Cycle 24 and the Solar Dynamo

    NASA Technical Reports Server (NTRS)

    Pesnell, W. D.; Schatten, K.

    2007-01-01

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

  10. Solar Cycle 24 and the Solar Dynamo

    NASA Astrophysics Data System (ADS)

    Pesnell, W. D.; Schatten, K.

    2007-05-01

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

  11. Solar Proton Events in Six Solar Cycles

    NASA Astrophysics Data System (ADS)

    Vitaly, Ishkov

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

  12. Correlations between attitude toward Christianity, prayer, and church attendance among 9- to 11-yr.-olds.

    PubMed

    Robbins, Mandy; Babington, Peter; Francis, Leslie J

    2004-02-01

    Data provided by 150 9- to 11-yr.-old primary school pupils in England showed scores on the Francis Scale of Attitude toward Christianity more highly correlated with (personal) prayer (r = .57) than with (public) church attendance (r = .23), providing support for the view that attitude scales access a deeper level of religiosity less contaminated by those contextual and social factors which may influence public church attendance more than personal prayer.

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

    NASA Astrophysics Data System (ADS)

    Pishkalo, M.

    2012-12-01

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

  14. Solar luminosity variations in solar cycle 21

    NASA Technical Reports Server (NTRS)

    Willson, Richard C.; Hudson, H. S.

    1988-01-01

    Long-term variations in the solar total irradiance found in the ACRIM I experiment on the SMM satellite have revealed a downward trend during the declining phase of solar cycle 21 of the sunspot cycle, a flat period between mid-1095 and mid-1987, and an upturn in late 1987 which suggests a direct correlation of luminosity and solar active region population. If the upturn continues into the activity maximum of solar cycle 22, a relation between solar activity and luminosity of possible climatological significance could be ascertained. The best-fit relationship for the variation of total irradiance S with sunspot number Rz and 10-cm flux F(10) are S = 1366.82 + 7.71 x 10 to the -3rd Rz and S = 1366.27 + 8.98 x 10 to the -3rd F(10)(W/sq m). These findings could be used to approximate total irradiance variations over the periods for which these indices have been compiled.

  15. Features of the Solar Active Cycles

    NASA Astrophysics Data System (ADS)

    Li, Kejun

    Characteristics of the sunspot cycle described by the international sunspot numbers are investigated based on the results obtained by Hathaway, Wilson, and Reichmann (1994). A long period of about 90 years is found to possibly exist for the sunspot number time series. Cycles that take less time to rise from minimum to maximum of cycle amplitude tend to have large amplitude, and those that have small maximum amplitude tend to run a long time to get ended. The sum of the sunspot numbers during the rising time of a solar cycle is almost equal to the total of the rest part of the solar cycle in spite of that the rising time of the solar cycle, or the cycle length is long or short. It is also found in this paper that the more recent cycles are larger in amplitude and shorter both in cycle length and the rising time of solar cycle than the earlier ones.

  16. A Synthesis of Solar Cycle Prediction Techniques

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    SciTech Connect

    Michael, A. T.; Opher, M.; Provornikova, E.; Richardson, J. D.; Tóth, G. E-mail: mopher@bu.edu E-mail: jdr@space.mit.edu

    2015-04-10

    In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in magnetic flux. We investigate the role of the 11 yr solar cycle variation of the magnetic field strength on the magnetic flux within the HS using a global 3D magnetohydrodynamic model of the heliosphere. We use time and latitude-dependent solar wind velocity and density inferred from Solar and Heliospheric Observatory/SWAN and interplanetary scintillations data and implemented solar cycle variations of the magnetic field derived from 27 day averages of the field magnitude average of the magnetic field at 1 AU from the OMNI database. With the inclusion of the solar cycle time-dependent magnetic field intensity, the model matches the observed intensity of the magnetic field in the HS along both Voyager 1 and 2. This is a significant improvement from the same model without magnetic field solar cycle variations, which was over a factor of two larger. The model accurately predicts the radial velocity observed by Voyager 2; however, the model predicts a flow speed ∼100 km s{sup −1} larger than that derived from LECP measurements at Voyager 1. In the model, magnetic flux is conserved along both Voyager trajectories, contrary to observations. This implies that the solar cycle variations in solar wind magnetic field observed at 1 AU does not cause the order of magnitude decrease in magnetic flux observed in the Voyager 1 data.

  18. Determination of Solar Cycle and Natural Climate Variation Using Both Surface Air/Soil Temperature and Thermal Diffusion Model

    NASA Astrophysics Data System (ADS)

    Dong, X.; Gosnold, W.

    2005-12-01

    Daily air and soil temperatures over KS, NE, SD and ND were obtained from High Plains Regional Climate Center (HPRCC) in Lincoln, NE from May 19, 1981 to December 31, 2003. A least-squares fit of the first five years of data is performed to determine the initial model temperature. A 2-D, finite-difference, conductive heat flow model was used with an initial condition T(x, 0) = 0 and boundary conditions of T(0, t) = the daily air/soil temperatures. The output of the model is a time series matrix of temperature vs. depth. The daily air/soil temperatures were averaged to compile a single record for each state and these data were used as the forcing signals in the model. The key to detection of the solar cycle and natural climate change is the filtering power of thermal diffusion which removes the short period signals (interannual) and retains the long period signals (decadal and centennial) in the upper 100 m. The temperature at a depth of 10 m has a good signal-to-noise ratio and represents 23 percent of its surface amplitude for the period of a solar cycle. There are two findings from this study: (1) Solar cycle, the temperature variations match the variations of the observed solar irradiance. This indicates that we can predict 11-yr solar cycles using both the surface air/soil temperatures as forcing signals in our thermal diffusion model. (2) Natural climate variation over the NGP during an 11-yr cycle ranges from 0.22 to 0.5 oC at 10 m deep and 0.42 to 0.94 oC at surface. This research is supported by NSF ATM-038384.

  19. Hilbert-Huang transform analysis of periodicities in the last two solar activity cycles

    NASA Astrophysics Data System (ADS)

    Kolotkov, D. Y.; Broomhall, A.-M.; Nakariakov, V. M.

    2015-08-01

    We investigated periodicities associated with the last two-and-a-half solar activity cycles with the novel Hilbert-Huang transform (HHT) method. Raw data signals of five different observational proxies: the 10.7 cm radio flux intensity, the helioseismic frequency shift, and the sunspot area signals recorded from the whole solar disc, and separately from the Northern and Southern hemispheres, were expanded into a set of intrinsic modes with the ensemble empirical mode decomposition technique. Instant and mean periods of each empirical mode were obtained with the use of the Hilbert transform applied independently to each separate mode. The periodicities were allocated to three distinct groups: short-term variations (with periods shorter than 0.5 yr), quasi-biennial oscillations (with typical periods from 0.5 yr to 3.9 yr), and longer periodicities, e.g. such as the 11 yr cycle. All periodicities detected in the examined solar cycles 22-24 are consistent with the well-known results found in the earlier solar epochs. We have demonstrated that the HHT method is a good tool for characterizing periodicities in the helioseismic data, which are necessarily relatively limited in terms of their time resolution. Periodicities obtained using the helioseismic data are, nevertheless, consistent with those found in other proxies. Since helioseismic oscillations are sensitive to the solar interior, this indicates that the behaviour of surface and atmospheric magnetic activity reflects that of the Sun's internal magnetic field. All identified intrinsic modes are seen to have clear amplitude modulation highly correlated with the 11 yr cycle. This amplitude modulation is most pronounced in the short-period modes. The short-term periodicities were found to be multiples of the shortest period, of 25 d. This ordering of the short-term periodicities is consistent with the previous findings. Signatures of the north-south asymmetry were detected in the individual hemisphere sunspot area

  20. Solar activity cycle - History and predictions

    SciTech Connect

    Withbroe, G.L. )

    1989-12-01

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

  1. Solar Irradiance Observations during Solar Cycles 22 and 23

    NASA Astrophysics Data System (ADS)

    White, O. R.; de Toma, G.; Chapman, G. A.; Walton, S. R.; Preminger, D. G.; Cookson, A. M.; Harvey, K. L.; Livingston, W. C.

    2002-05-01

    We present a study of Total Solar Irradiance (TSI) variations during solar cycles 22 and 23 from 1986 to the present. We will review the recent measurements of solar magnetism, solar activity, and radiative variability from both ground-based and space observatories and compare TSI observations with empirical models of solar irradiance variability based on facular and sunspot observations. To estimate facular/plage and sunspot contribution to TSI we use the photometric indices derived from the SFO full-disk solar images from 1988 to the present in the CaIIK line at 393.4nm and in the red continuum at 672.3 nm. In these indices, each solar structure is included with its measured contrast and area. We also use the MgII core-to-wing index from space observatories as an alternative index for plages and network. Comparison of the rising and maximum phases of the two solar cycles, shows that cycle 23 is magnetically weaker with sunspot and facular area almost a factor of two lower than in solar cycle 22. However, analysis of multi-wavelength observations indicate that different wavelengths respond differently to the decreased magnetic activity during solar cycle 23.

  2. Predicting Solar Cycle 24 and beyond

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  3. Variation in electromagnetic parameters of the solar magnetic cycle as cause of the 22-year oscillation in global temperature and rotation rate of the Earth

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Tamara; Laptukhov, Alexej

    Solar radiation is not the only heat source of the upper atmosphere. Solar energy is captured by magnetosphere and atmosphere via electromagnetic interaction of the solar wind with terrestrial field. Aim of the paper is to explain correlated 22-year variations of sunspot numbers W, global temperature Tgl and angular velocity w of the Earth derived by us on basis of observational data. First of all we analyze data of the interplanetary magnetic field (IMF) and the solar wind velocity measured at the Earth's orbit for the period of 1964-2005. Based on the data we show that heliomagnetic moment during 11-year solar activity cycle changes its direction, rotating from north pole through equators to south pole, and back. Manifestation of this magnetic solar cycle is annual variation of the electromagnetic parameters. The annual variations of values of electric field E, vector of Poyting P, IMF were obtained for different phases of the 22-yr solar cycle. We show that all the parameters are higher for odd 11-yr cycles than ones for even 11-yr cycles (11-yr cycle is determined between maxima of W). Moreover, the contrast between two cycles displays strength in summer months, when heat machine in atmosphere raised by the temperature difference between sunlit north polar cap and dark south polar cap works actively. The difference of the parameters of W1 and W2 cycles leads in the end to difference of their influence to polar magnetosphere and ionosphere. Processes in magnetosphere controlled by the solar wind causes two main phenomena in the upper polar atmosphere: particle precipitation and convection of ionospheric plasma caused by E. The particle precipitation influences on conductivities and currents. As result the Poyting flux P=[ExB] coming to polar cap leads to heating of polar ionosphere and atmosphere, temperature contrast between two caps, intensification of the inter-hemisphere heat machine in the upper atmosphere, change of angular moment of atmospheric zonal

  4. Solar Wind Overview of Cycle 24

    NASA Astrophysics Data System (ADS)

    Galvin, Antoinette; Farrugia, Charles; Kucharek, Harald; Yu, Wenyuan

    2017-04-01

    The STEREO observatories were commissioned in early 2007, near the end of solar cycle 23, and has continued (outside of the solar conjunction blackout period) providing data into the present phase of cycle 24. During the approach to solar minimum (2007-2008), there are two well-delineated regions of higher speed solar wind (> 500 km/s), associated with the central meridian passage of coronal holes and correlated with lower densities, lower iron ionic charge states, and uniform magnetic polarity. Preceding these regions are higher density ridges associated with stream interaction regions. During the recent solar minimum (2008-2010) there were significant intervals of slow speed solar wind, including small transients (Yu et al., 2016) and slow interplanetary coronal mass ejections. ICMEs characterized by higher speeds and higher iron charge states became more prevalent as the cycle reached solar maximum (2013-2014). We are currently in the declining phase of solar activity in this cycle, though ICME events are still being observed. We present overview synoptic solar wind data as seen at STEREO A for the mission to date and frequency distributions of solar wind iron charge states over time.

  5. Cycle 23 Variation in Solar Flare Productivity

    NASA Astrophysics Data System (ADS)

    Hudson, Hugh; Fletcher, Lyndsay; McTiernan, Jim

    2014-04-01

    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.

  6. Cycles and Anti-Cycles of Solar Activity

    NASA Astrophysics Data System (ADS)

    Ryabov, M. I.

    Currently representation of solar cycles on average monthly data and smoothed values on various indexes from the full solar disk is generally accepted. Such representation creates an illusion of monotone change and perceptions of simultaneity of manifestations of solar activity for all solar disc. At the same time, daily monitoring data reveal the presence of discrete properties of manifestations of solar cycle. They are associated with absence of spots on the Sun in the northern and southern hemispheres at different intervals. This phenomenon is defined as anti-cycle of solar activity. Properties of discreteness of anti-cycles are presented in this paper on "spotless days' periods". On their basis the appropriate monthly and annual data was received. The basic characteristics of the manifestations of the discreteness of activity anti-cycles had been determined. It noted the "switch effect" of the existence of the solar dynamo. It manifests itself in the rapid transition from a regime of "spotless days" to the regime of continuous generation.

  7. The solar wind throughout the solar cycle

    NASA Astrophysics Data System (ADS)

    von Steiger, Rudolf

    The existence of solar corpuscular radiation (SCR) was conjectured by Biermann (1951) based on the fact that the ion tails of comets always point radially away from the Sun. Earlier it had been thought that this was due to solar radiation pressure, but when the relevant cross-sections were measured it became clear that these were far too small. This is visible in Figure 3.1, where stars can be seen shining through the ion tail of comet Hale-Bopp, one of the more spectacular sights in the sky of the 20th century. Parker (1958) provided the first theoretical description of the SCR in terms of a supersonic magnetized fluid. He coined the term "solar wind" in order to set it apart from other ideas of a (subsonic) solar breeze that were around at the time. The solar wind was ultimately observed in the early 1960s by the Soviets and independently with the American Mariner 2 mission to Venus (Gringauz et al., 1961; Neugebauer and Snyder, 1962). An excellent account of these early developments is given by Parker (2001).

  8. Pulsed nature of solar cycle 24

    NASA Astrophysics Data System (ADS)

    Benevolenskaya, E. E.; Ponyavin, Yu. D.

    2015-12-01

    Solar cycle 24 is characterized by relatively weak sunspot activity and is developing according to the smallest cycle scenario (Svalgaard, Cliver, and Kamide, 2005). Using the Solar Dynamics Observatory (SDO) data for May 2010-September 2014, we present the results of a study of solar cycle 24 in the photosphere and corona during the ascending and maximum epochs. These data have been prepared in the form of synoptic maps (one map corresponds to one solar rotation) as functions of latitude and longitude for Carrington rotations CR2097-CR2154. To study the axisymmetric structure of the cycle, the maps have been averaged over longitude. Solar activity pulses, which are visible in an axisymmetric midlatitude magnetic flux, correspond to coronal brightening events in the extreme ultraviolet in the 193 Å band. Solar cycle 24 is characterized by weak magnetic polar activity, weakly pronounced high-latitude waves of coronal activity, and north-south asymmetry in the sign change of the polar solar magnetic field, which is directly connected with the asymmetry in an emerging magnetic flux in the region of sunspot activity and, hence, solar activity pulses. Thus, the north polar field became mainly positive in the latitude zone from 75.01° to 79.73° in 2013, while the south field started changing sign in September 2014.

  9. Solar-cycle precursors and predictions

    NASA Astrophysics Data System (ADS)

    Jiang, Jie

    2013-07-01

    The sunspot number data during the past 400 years indicates that both the profile and the amplitude of the solar cycle have large variations. Some precursors of the solar cycle were identified aiming to predict the solar cycle. The polar field and the geomagnetic index are two precursors which are received the most attention. The geomagnetic variations during the solar minima are potentially caused by the solar polar field by the connection of the solar open flux. The robust prediction skill of the polar field indicates that the memory of the dynamo process is less than 11 yrs based on the frame of the Babcock-Leighton flux transport dynamo. One possible reason to get the short magnetic memory is the high magnetic diffusivity in the convective zone. Our recent studies show that the radial downward pumping is another possible reason. Based upon the mechanism, we well simulate the cycle irregularities during RGO time period. This opens the possibility to set up a standard dynamo based model to predict the solar cycle. In the end, the no correlation between the polar field and the preceding cycle strength due to two nonlinearities involved in the sunspot emergence will be stressed.

  10. Solar cycle 24 from the standpoint of solar paleoastrophysics

    NASA Astrophysics Data System (ADS)

    Ogurtsov, M. G.

    2016-03-01

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

  11. POLAR NETWORK INDEX AS A MAGNETIC PROXY FOR THE SOLAR CYCLE STUDIES

    SciTech Connect

    Priyal, Muthu; Banerjee, Dipankar; Ravindra, B.; Singh, Jagdev; Karak, Bidya Binay; Muñoz-Jaramillo, Andrés; Choudhuri, Arnab Rai E-mail: dipu@iiap.res.in

    2014-09-20

    The Sun has a polar magnetic field which oscillates with the 11 yr sunspot cycle. This polar magnetic field is an important component of the dynamo process which operates in the solar convection zone and produces the sunspot cycle. We have direct systematic measurements of the Sun's polar magnetic field only from about the mid-1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal Solar Observatory during 1904-2007 have now been digitized with 4k × 4k CCD and have higher resolution (∼0.86 arcsec) than the other available historical data sets. From these Ca-K spectroheliograms, we have developed a completely new proxy (polar network index, hereafter PNI) for the Sun's polar magnetic field. We calculate 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 1976-1990. This calibration allows us to estimate the polar fields for the earlier period up to 1904. The dynamo calculations performed with this proxy as input data reproduce reasonably well the Sun's magnetic behavior for the past century.

  12. Polar Network Index as a Magnetic Proxy for the Solar Cycle Studies

    NASA Astrophysics Data System (ADS)

    Priyal, Muthu; Banerjee, Dipankar; Karak, Bidya Binay; Muñoz-Jaramillo, Andrés; Ravindra, B.; Choudhuri, Arnab Rai; Singh, Jagdev

    2014-09-01

    The Sun has a polar magnetic field which oscillates with the 11 yr sunspot cycle. This polar magnetic field is an important component of the dynamo process which operates in the solar convection zone and produces the sunspot cycle. We have direct systematic measurements of the Sun's polar magnetic field only from about the mid-1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal Solar Observatory during 1904-2007 have now been digitized with 4k × 4k CCD and have higher resolution (~0.86 arcsec) than the other available historical data sets. From these Ca-K spectroheliograms, we have developed a completely new proxy (polar network index, hereafter PNI) for the Sun's polar magnetic field. We calculate 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 1976-1990. This calibration allows us to estimate the polar fields for the earlier period up to 1904. The dynamo calculations performed with this proxy as input data reproduce reasonably well the Sun's magnetic behavior for the past century.

  13. Solar neutrino flux, cosmic rays, and the solar activity cycle

    NASA Astrophysics Data System (ADS)

    Raychaudhuri, P.

    1986-04-01

    It is suggested that the experimental data on the solar neutrino flux as measured by Davis et al. (1983) from 1970 to 1982 vary with the solar activity cycle to a very high level of statistical significance for all the available tests of the hypothesis (e.g., t-test, run test, Wilcoxon-Mann-Whitney test) when the solar neutrino flux data are computed from the weighted moving averages of order 5. The above tests have also been applied to the data that have been generated by the Monte Carlo simulation with production rate and background rate parameters that are typical of those in the actual experiment. It is shown that the Monte Carlo simulated data do not indicate a variation within the solar cycle. Thus the moving-average data strongly favor the variation within the solar activity cycle.

  14. A Decline in Solar Cycle Strength

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Features of the solar active cycles.

    NASA Astrophysics Data System (ADS)

    Li, Kejun

    1999-12-01

    Characteristics of the sunspot cycle described by the international sunspot numbers are investigated based on the results obtained by Hathaway, Wilson, and Reichmann (1994). A long period of about 90 years is found to possibly exist for the sunspot number time series. Cycles that take less time to rise from minimum to maximum of cycle amplitude tend to have large amplitude, and those that have small maximum amplitude tend to run a long time to get ended. It is also found that the more recent cycles are larger in amplitude and shorter both in cycle length and the rising time of solar cycle than the earlier ones.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  19. On Solar Flares and Cycle 23

    NASA Astrophysics Data System (ADS)

    Kossobokov, Vladimir; Le Mouël, Jean-Louis; Courtillot, Vincent

    2012-02-01

    The anomalous character of Solar Cycle 23, which ended in the Summer of 2009, has been pointed out by many authors. It has even been proposed that the solar dynamo is undergoing a transition from a state of “grand maximum” to one of “regular oscillations”. We analyze the temporal distribution of the number and energy of solar flares, and the duration of intervals between them, over Cycles 21 to 23. We consider 32 355 flares of class C2 and larger (C2+) from the GOES catalogue. Daily values of X-ray flux (wavelengths 1 to 8 Å) have been computed by summing the energy proxies of the events. The series of daily numbers of C2+ solar flares are strongly correlated with their daily energy flux. The long duration of Cycle 23 (12.8 years based on sunspots, 13.2 years based on flares) and the long interval with no C2+ flare between the end of Cycle 23, and the start of Cycle 24 (466 days) are remarkable compared to the two earlier cycles. The amplitudes of extreme flares increase when the mean flux decreases. We have calculated running averages of energy flux over intervals going from 7 to 365 days. The singular shape of Cycle 23 is increasingly striking with increasing interval: in the first ≈ 70% of the cycle (displayed on a logarithmic scale) we see linearly rising maxima, whereas minima are aligned along a descending slope for the latter part of the cycle. The energy flux oscillates between these and takes the shape of a bifurcation, starting near 2002 (a time when it is suggested that photospheric fields were abruptly reduced). Inter-event intervals between successive C2+ flares undergo quasi-periodic (≈ 11 years) oscillations between two distinct states, which we call “active” and “quiet”, with extremely sharp onset and termination. The ratio of time spent in the active vs. quiet states ranges from 1.8 to 1.4 for Cycles 21 to 23, Cycle 23 having the longest quiet period. It has been proposed that anomalous Cycle 23 resembles Cycle 4, which was

  20. Forecasting Solar Activity and Cycle 23 Outlook

    NASA Astrophysics Data System (ADS)

    Schatten, K.; Sofia, S.

    1996-12-01

    "Precursor Techniques" have, in general, been fairly successful at predicting solar activity for a few solar cycles. These early precursors were based upon examining geomagnetic fluctuations features near solar minimum to ascertain the level of the next cycle's solar activity. In the 70's, the case was made that for these techniques to work, there would need to be a "connection" to the solar dynamo, and it was suggested that the precursors were "measuring" the Sun's polar field. Using proxies for the Sun's polar field, and the polar field itself, this "dynamo precursor method" successfully predicted the last two solar cycles. We will discuss the physical bases for these methods. We also shall present a generalization to a "SODA" (SOlar Dynamo Amplitude) index, which is used to estimate the amount of magnetism below the Sun's surface. This SODA index provides a measure of the amount of "magnetic fizz" below the Sun's surface, and also the state of the Sun's dynamo. Using these methods we predict cycle 23 will peak near 180 +/- 30 in smoothed F10.7 Radio Flux, and near 130 +/- 30 in smoothed Sunspot number in the year 2000.

  1. Global water cycle and solar activity variations

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  2. Sudden ionospheric disturbances in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Bothmer, Volker; Bernert, Barbara

    2014-05-01

    Sudden ionospheric disturbances in solar cycle 24 Within the framework of the UN International Space Weather Initiative, and building upon the achievements of the International Heliophysical Year, the German project SIMONE (Sun Ionosphere MOnitoring NEtwork) operates several SID monitors provided by the University of Stanford. Here we present an overview of sudden ionospheric disturbances recorded since 2006 at the high school Gymnasium Walsrode until to date. The continous measurements allow a detailed comparison of locally measured SIDs with the general trend of solar activity during the current solar maximum. We further show that the measurements reveal specific information on the variable response of the dayside ionosphere to solar flares.

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

    NASA Astrophysics Data System (ADS)

    Ogurtsov, M. G.

    2012-12-01

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

  4. Magnetic network elements in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Jin, Chunlan; Wang, Jingxiu

    2013-07-01

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

  5. Solar cycle response and long-term trends in the mesospheric metal layers

    NASA Astrophysics Data System (ADS)

    Dawkins, E. C. M.

    2016-12-01

    The meteoric metal layers (Na, Fe, K) - which form as a result of the ablation of incoming meteors - act as unique tracers for chemical and dynamical processes that occur within the upper mesosphere/lower thermosphere (MLT) region. Here we examine whether these metal layers are sensitive indicators of decadal long-term changes within the upper atmosphere. Output from the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) is used to assess the response of the Na, K and Fe layers across a 50-year period (1955-2005). At short timescales, the K layer has previously been shown to exhibit a very different seasonal behavior compared to the other metals. In this work, we demonstrate that this unusual behavior is also exhibited at longer timescales (both the 11-yr solar cycle and 50-year periods), with K displaying a much more pronounced response to atmospheric temperature changes than either Na or Fe. The contrasting 11-year solar cycle behavior of the K and Na layers predicted by the model is confirmed using new satellite and lidar observations for the period 2004-2015. Overall, the results presented here demonstrate that the unusual behavior of K compared to Na and Fe is present not only at diurnal and seasonal timescales, but also over longer-term periods, which may lead to the K layer being a sensitive indicator of long-term changes in the MLT region.

  6. Solar cycle modulation of Southern Annular Mode

    NASA Astrophysics Data System (ADS)

    Kuroda, Yuhji

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  8. Solar Observations In Cycle 4 Of ALMA

    NASA Astrophysics Data System (ADS)

    Shimojo, Masumi; ALMA Solar Development Team

    2016-07-01

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

  9. Solar Cycles - to Updating Basic Parameters

    NASA Astrophysics Data System (ADS)

    Ryabov, M. I.

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

  10. Solar Spectral Irradiance Changes During Cycle 24

    NASA Technical Reports Server (NTRS)

    Marchenko, Sergey; Deland, Matthew

    2014-01-01

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

  11. Solar spectral irradiance changes during cycle 24

    SciTech Connect

    Marchenko, S. V.; DeLand, M. T.

    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.

  12. On Solar Cycle Predictions and Reconstructions

    DTIC Science & Technology

    2008-12-01

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

  13. Prediction Methods in Solar Sunspots Cycles

    PubMed Central

    Ng, Kim Kwee

    2016-01-01

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

  14. Prediction Methods in Solar Sunspots Cycles.

    PubMed

    Ng, Kim Kwee

    2016-02-12

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

  15. Prediction Methods in Solar Sunspots Cycles

    NASA Astrophysics Data System (ADS)

    Ng, Kim Kwee

    2016-02-01

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

  16. Solar cycle changes in the polar solar wind

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  18. Solar Cycle Variation of CMEs and CIRs

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2011-01-01

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

  19. Solar Cycle Variations in the Polar Ionosphere

    NASA Astrophysics Data System (ADS)

    Burrell, A. G.; Yeoman, T. K.; Milan, S. E.; Lester, M.

    2014-12-01

    The polar ionosphere is a dynamic region that readily responds to changes in solar irradiance, solar wind, the magnetosphere, and the neutral atmosphere. The most recent solar minimum brought to light gaps in the current understanding of the relationship between ionospheric structure and solar irradiance. The Super Dual Auroral Radar Network (SuperDARN) offers an invaluable dataset for studying long-term ionospheric variability, as it has been continuously providing extensive coverage of the northern and southern polar ionosphere since 1995 (the solar minimum preceding the 23rd solar cycle). An under-utilized portion of the SuperDARN dataset is the ground-backscatter: the backscatter that returns from a reflection point on the ground along an open (or irregularity-free) propagation path. The ground-backscatter provides a measure the ionospheric density at the peak of the radar signal's path. These measurements are used to the examine the changes in the bottomside, polar ionosphere over the 23rd and 24th solar cycles.

  20. Sources of solar wind over the solar activity cycle

    PubMed Central

    Poletto, Giannina

    2012-01-01

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

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

    PubMed

    Poletto, Giannina

    2013-05-01

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

  2. Coronal Activity and Extended Solar Cycles

    NASA Astrophysics Data System (ADS)

    Altrock, R. C.

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Chandra, S.

    1991-01-01

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

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

    SciTech Connect

    Chandra, S.

    1991-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Chandra, S.

    1991-01-01

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

  6. Solar Cycle 23 in Coronal Bright Points

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  7. Study of the Solar Cycle from Space

    NASA Technical Reports Server (NTRS)

    1980-01-01

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

  8. The Heliosphere Through the Solar Activity Cycle

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Lanzerotti, L. J.; Suess, S. T.

    2006-01-01

    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 describe the rise in solar ESA and NASA have now unamiously agreed a third extension to operate the highly successful Ulysses spacecraft until March 2008 and, in 2007 and 2008, the European-built space probe will fly over the poles of the Sun for a third time. This will enable Ulysses to add an important chapter to its survey of the high-latitude heliosphere and this additional material would be included in a 2nd edition of this book.

  9. Geomagnetism during solar cycle 23: Characteristics.

    PubMed

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

    2013-05-01

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

  10. Geomagnetism during solar cycle 23: Characteristics

    PubMed Central

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

    2012-01-01

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

  11. SOLAR CYCLE VARIABILITY AND SURFACE DIFFERENTIAL ROTATION FROM Ca II K-LINE TIME SERIES DATA

    SciTech Connect

    Scargle, Jeffrey D.; Worden, Simon P.; Keil, Stephen L.

    2013-07-01

    Analysis of over 36 yr of time series data from the NSO/AFRL/Sac Peak K-line monitoring program elucidates 5 components of the variation of the 7 measured chromospheric parameters: (a) the solar cycle (period {approx} 11 yr), (b) quasi-periodic variations (periods {approx} 100 days), (c) a broadband stochastic process (wide range of periods), (d) rotational modulation, and (e) random observational errors, independent of (a)-(d). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these parameters. Time-frequency analysis illuminates periodic and quasi-periodic signals, details of frequency modulation due to differential rotation, and in particular elucidates the rather complex harmonic structure (a) and (b) at timescales in the range {approx}0.1-10 yr. These results using only full-disk data suggest that similar analyses will be useful for detecting and characterizing differential rotation in stars from stellar light curves such as those being produced by NASA's Kepler observatory. Component (c) consists of variations over a range of timescales, in the manner of a 1/f random process with a power-law slope index that varies in a systematic way. A time-dependent Wilson-Bappu effect appears to be present in the solar cycle variations (a), but not in the more rapid variations of the stochastic process (c). Component (d) characterizes differential rotation of the active regions. Component (e) is of course not characteristic of solar variability, but the fact that the observational errors are quite small greatly facilitates the analysis of the other components. The data analyzed in this paper can be found at the National Solar Observatory Web site http://nsosp.nso.edu/cak{sub m}on/, or by file transfer protocol at ftp://ftp.nso.edu/idl/cak.parameters.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  13. Influence of Solar Cycles on Earthquakes

    NASA Astrophysics Data System (ADS)

    Tavares, M.

    2011-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Pesnell. William Dean

    2008-01-01

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

  15. The effects of 11 yr of CO₂ enrichment on roots in a Florida scrub-oak ecosystem.

    PubMed

    Day, Frank P; Schroeder, Rachel E; Stover, Daniel B; Brown, Alisha L P; Butnor, John R; Dilustro, John; Hungate, Bruce A; Dijkstra, Paul; Duval, Benjamin D; Seiler, Troy J; Drake, Bert G; Hinkle, C Ross

    2013-11-01

    Uncertainty surrounds belowground plant responses to rising atmospheric CO₂ because roots are difficult to measure, requiring frequent monitoring as a result of fine root dynamics and long-term monitoring as a result of sensitivity to resource availability. We report belowground plant responses of a scrub-oak ecosystem in Florida exposed to 11 yr of elevated atmospheric CO₂ using open-top chambers. We measured fine root production, turnover and biomass using minirhizotrons, coarse root biomass using ground-penetrating radar and total root biomass using soil cores. Total root biomass was greater in elevated than in ambient plots, and the absolute difference was larger than the difference aboveground. Fine root biomass fluctuated by more than a factor of two, with no unidirectional temporal trend, whereas leaf biomass accumulated monotonically. Strong increases in fine root biomass with elevated CO₂ occurred after fire and hurricane disturbance. Leaf biomass also exhibited stronger responses following hurricanes. Responses after fire and hurricanes suggest that disturbance promotes the growth responses of plants to elevated CO₂. Increased resource availability associated with disturbance (nutrients, water, space) may facilitate greater responses of roots to elevated CO₂. The disappearance of responses in fine roots suggests limits on the capacity of root systems to respond to CO₂ enrichment.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  17. Solar cycle variations of magnetopause locations

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  18. Dynamics of solar wind speed: Cycle 23

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  19. A thermodynamic cycle for the solar cell

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  20. CHARACTERISTICS OF SOLAR MERIDIONAL FLOWS DURING SOLAR CYCLE 23

    SciTech Connect

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

    2010-07-01

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

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

    NASA Astrophysics Data System (ADS)

    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).

  2. On the seat of the solar cycle

    NASA Technical Reports Server (NTRS)

    Gough, D.

    1981-01-01

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

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

    PubMed

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

    2013-05-01

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

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

    PubMed Central

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

    2012-01-01

    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. PMID:25685422

  5. Solar cycle variations of thermospheric composition at the solstices

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Raychaudhuri, P.

    1985-01-01

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

  7. Global Solar Magnetology and Reference Points of the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Obridko, V. N.; Shelting, B. D.

    2003-11-01

    The solar cycle can be described as a complex interaction of large-scale/global and local magnetic fields. In general, this approach agrees with the traditional dynamo scheme, although there are numerous discrepancies in the details. Integrated magnetic indices introduced earlier are studied over long time intervals, and the epochs of the main reference points of the solar cycles are refined. A hypothesis proposed earlier concerning global magnetometry and the natural scale of the cycles is verified. Variations of the heliospheric magnetic field are determined by both the integrated photospheric i(B r )ph and source surface i(B r )ss indices, however, their roles are different. Local fields contribute significantly to the photospheric index determining the total increase in the heliospheric magnetic field. The i(B r )ss index (especially the partial index ZO, which is related to the quasi-dipolar field) determines narrow extrema. These integrated indices supply us with a “passport” for reference points, making it possible to identify them precisely. A prominent dip in the integrated indices is clearly visible at the cycle maximum, resulting in the typical double-peak form (the Gnevyshev dip), with the succeeding maximum always being higher than the preceding maximum. At the source surface, this secondary maximum significantly exceeds the primary maximum. Using these index data, we can estimate the progression expected for the 23rd cycle and predict the dates of the ends of the 23rd and 24th cycles (the middle of 2007 and December 2018, respectively).

  8. Brayton cycle solarized advanced gas turbine

    NASA Technical Reports Server (NTRS)

    1986-01-01

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

  9. Major Geomagnetic Storms in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Zheng, Y.

    2013-12-01

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

  10. Solar cycle variation of magnetic flux emergence

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  11. Properties and Surprises of Solar Activity XXIII Cycle

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  13. Flux-tube geometry and solar wind speed during an activity cycle

    NASA Astrophysics Data System (ADS)

    Pinto, R. F.; Brun, A. S.; Rouillard, A. P.

    2016-07-01

    Context. The solar wind speed at 1 AU shows cyclic variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal (asymptotic) wind speed in a given magnetic flux-tube is generally anti-correlated with its total expansion ratio, which motivated the definition of widely used semi-empirical scaling laws relating one to the other. In practice, such scaling laws require ad hoc corrections (especially for the slow wind in the vicinities of streamer/coronal hole boundaries) and empirical fits to in situ spacecraft data. A predictive law based solely on physical principles is still missing. Aims: We test whether the flux-tube expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes (close to and far from streamer boundaries) using a very large sample of wind-carrying open magnetic flux-tubes. We furthermore search for additional physical parameters based on the geometry of the coronal magnetic field which have an influence on the terminal wind flow speed. Methods: We use numerical magneto-hydrodynamical simulations of the corona and wind coupled to a dynamo model to determine the properties of the coronal magnetic field and of the wind velocity (as a function of time and latitude) during a whole 11-yr activity cycle. These simulations provide a large statistical ensemble of open flux-tubes which we analyse conjointly in order to identify relations of dependence between the wind speed and geometrical parameters of the flux-tubes which are valid globally (for all latitudes and moments of the cycle). Results: Our study confirms that the terminal (asymptotic) speed of the solar wind depends very strongly on the geometry of the open magnetic flux-tubes through which it flows. The total flux-tube expansion is more clearly anti-correlated with the wind speed for fast rather than for slow wind flows, and effectively controls the

  14. Variations of the ionosphere and related solar fluxes during solar cycles 21 and 22

    NASA Astrophysics Data System (ADS)

    Balan, N.; Bailey, G. J.; Su, Y. Z.

    The ionospheric electron content (IEC) and peak electron density (NmF2) data collected at low- and mid-latitudes during 1980-1991 and values of solar EUV (50 -1050 Angstroms) fluxes obtained from the EUV91 solar EUV flux model are analysed to study the variations of the ionosphere during the intense solar cycles 21 and 22. The study shows that while the ionosphere responds linearly to the solar EUV fluxes its variation with the conventional solar activity index F10.7 is non-linear during both solar cycles. The behaviour of the ionosphere during the most intense solar cycle 19 has been shown to be similar to that during solar cycles 21 and 22. The ionospheric variations confirm that the relationship between the shorter (EUV and UV) and longer (10.7 cm) wavelength solar fluxes is non-linear during all solar cycles.

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

    NASA Technical Reports Server (NTRS)

    Berman, A. L.

    1978-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  17. Simulations of a dynamic solar cycle and its effects on the interstellar boundary explorer ribbon and globally distributed energetic neutral atom flux

    DOE PAGES

    Zirnstein, E. J.; Heerikhuisen, J.; Pogorelov, N. V.; ...

    2015-04-23

    Observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs); this informs us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolution of themore » solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokol et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, these results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solar cycle, but rather with short-term fluctuations in the background plasma. And, while the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.« less

  18. SIMULATIONS OF A DYNAMIC SOLAR CYCLE AND ITS EFFECTS ON THE INTERSTELLAR BOUNDARY EXPLORER RIBBON AND GLOBALLY DISTRIBUTED ENERGETIC NEUTRAL ATOM FLUX

    SciTech Connect

    Zirnstein, E. J.; Heerikhuisen, J.; Pogorelov, N. V.; McComas, D. J.; Dayeh, M. A.

    2015-05-01

    Since 2009, observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs), which inform us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolution of the solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokół et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, our results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solar cycle, but rather with short-term fluctuations in the background plasma. While the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.

  19. Simulations of a dynamic solar cycle and its effects on the interstellar boundary explorer ribbon and globally distributed energetic neutral atom flux

    SciTech Connect

    Zirnstein, E. J.; Heerikhuisen, J.; Pogorelov, N. V.; McComas, D. J.; Dayeh, M. A.

    2015-04-23

    Observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs); this informs us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolution of the solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokol et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, these results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solar cycle, but rather with short-term fluctuations in the background plasma. And, while the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.

  20. One Possible Reason for Double-Peaked Maxima in Solar Cycles: Is a Second Maximum of Solar Cycle 24 Expected?

    NASA Astrophysics Data System (ADS)

    Kilcik, A.; Ozguc, A.

    2014-04-01

    We investigate solar activity by focusing on double maxima in solar cycles and try to estimate the shape of the current solar cycle (Cycle 24) during its maximum. We analyzed data for Solar Cycle 24 by using Learmonth Solar Observatory sunspot-group data collected since 2008. All sunspot groups (SGs) recorded during this time interval were separated into two groups: The first group includes small SGs [A, B, C, and H classes according to the Zurich classification], the second group consists of large SGs [D, E, and F]. We then calculated how many small and large sunspot groups occurred, their sunspot numbers [SSN], and the Zurich numbers [ Rz] from their daily mean numbers as observed on the solar disk during a given month. We found that the temporal variations for these three different separations behave similarly. We also analyzed the general shape of solar cycles from Cycle 1 to 23 by using monthly International Sunspot Number [ISSN] data and found that the durations of maxima were about 2.9 years. Finally, we used the ascending time and SSN relationship and found that the maximum of Solar Cycle 24 is expected to occur later than 2011. Thus, we conclude that i) one possible reason for a double maximum in solar cycles is the different behavior of large and small sunspot groups, and ii) a double maximum is expected for Solar Cycle 24.

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

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Silverman, S.

    1980-01-01

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

  2. Predicting Solar Cycle 25 using Surface Flux Transport Model

    NASA Astrophysics Data System (ADS)

    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.

  3. A Survey and Synthesis of Solar Cycle Prediction Techniques

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    A number of techniques for predicting solar activity on a solar cycle time scale are identified, described, and tested with historical data. Some techniques, e.g. regression and curve-fitting, work well as solar activity approaches maximum and provide a complete description of future activity, while others, e.g. geomagnetic precursors, work well near solar minimum but only provide an estimate of the amplitude of the cycle. A synthesis of different techniques is shown to provide a more accurate and useful forecast of solar cycle activity levels. A combination of two uncorrelated geomagnetic precursor techniques provides the most accurate prediction for the amplitude of a solar activity cycle at a time well before activity minimum. This Combined Precursor Method gives a smoothed sunspot number maximum of 154+/-21 at the 95% level of confidence for the next cycle maximum. A mathematical function dependent upon the time of cycle initiation and the cycle amplitude then describes the level of solar activity for the next complete cycle. As the time of cycle maximum approaches a better estimate of the cycle activity is obtained by including the fit between previous activity levels and this function. This Combined Solar Cycle Activity Forecast gives, as of January 1999, a smoothed sunspot maximum of 146+/-20 at the 95% level of confidence for the next cycle maximum. The success of the geomagnetic precursors in predicting future solar activity suggests that solar magnetic phenomena at latitudes above the sunspot activity belts are linked to solar activity which occurs many years later in the lower latitudes.

  4. Solar cycle and equatorial stratopause temperature

    NASA Astrophysics Data System (ADS)

    Mohanakumar, K.; Devanarayanan, S.

    1983-03-01

    The relationship between the stratopause temperature and solar activity, as represented by the Zuerich sunspot number, is studied. Stratopause temperatures were obtained from monthly mean temperature data of four equatorial rocket launching stations: Ascension Island, Kwajalein, and Fort Sherman during 1969-76, and Thumba during December 1970-76. The data were divided into winter, summer, and equinoctial periods, and the correlation coefficient, regression coefficient, and value of N were calculated. Positive, significant values of both coefficients are found for all the stations, showing that the stratopause temperature is influenced by the sunspot cycle, especially during the equinoctial periods. A wavy pattern is observed in the stratopause temperature over both Thumba and Kwajalein.

  5. Variability of Clouds Over a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2002-01-01

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

  6. Solar UV Variations During the Decline of Cycle 23

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  7. Hemispheric progression of solar cycles in solar magnetic field data and its relation to the solar dynamo models

    NASA Astrophysics Data System (ADS)

    Inceoglu, F.; Simoniello, R.; Knudsen, M. F.; Karoff, C.

    2017-05-01

    Aims: We aim to characterise the solar cycle progression simultaneously at different latitudes in each solar hemisphere using solar magnetic field data provided by the Wilcox Solar Observatory (WSO). We also investigate whether the features observed in the WSO data are best explained by the Babcock-Leighton (BL) mechanism and/or turbulent helicity as the α-effect in solar dynamos. Methods: We analysed the hemispheric solar-cycle progression of the Sun's magnetic field in different 15° latitudinal bands, which allow us to explore the extent of cycle overlap. We also investigated the Waldmeier Rule, and the relationship between decay rates and peak amplitudes of the same cycle. These aspects of the solar-cycle progression can be explained in different ways by solar dynamo models depending on the source of the α-effect. Results: The progression of the last four solar cycles in different latitudinal bands reveals that the degree of overlap between consecutive cycles is small and is more likely to be confined to low solar latitudes. We also found that the southern and northern solar hemispheres behave differently for the last four solar cycles, suggesting a slight decoupling between the hemispheres. The results also reveal a strong correlation between the decay rates and the peak amplitudes of the solar cycles.

  8. INTERNAL-CYCLE VARIATION OF SOLAR DIFFERENTIAL ROTATION

    SciTech Connect

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

    2013-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  10. Predicting Solar Cycle 24 Using a Geomagnetic Precursor Pair

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean

    2014-01-01

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

  11. Hybrid solar central receiver for combined cycle power plant

    DOEpatents

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

    1995-01-01

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

  12. Hybrid solar central receiver for combined cycle power plant

    DOEpatents

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

    1995-05-23

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

  13. Large Energetic Particle Pressures in Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A. F.; Wimmer-Schweingruber, R. F.; Berger, L.

    2017-09-01

    We study periods of elevated energetic particle intensities observed at the L1 Sun-Earth Lagrangian point when the partial energy density associated with energetic (≥80 keV) particles (PEP) dominates that of the local magnetic field (PB) and thermal plasma populations (PPLS). These periods are not uncommon and are frequently observed prior to the passage of interplanetary (IP) shocks. Because of the significant decreases in key solar wind parameters observed during solar cycle 24 [e.g., 1], we were motivated to perform a comparative statistical analysis to determine if the occurrence rate of periods when PEP exceeded PB or PPLS, or both, differed between solar cycles 23 and 24. We find that the general decrease of PB and PPLS in solar cycle 24 was also accompanied by a general decrease of periods with elevated PEP. The result is that solar cycle 24 showed a lower number of time intervals dominated by PEP. We analyze whether these differences can be related to the properties of the IP shocks observed at L1. Incomplete datasets of shock parameters do not show significant differences between solar cycles 23 and 24 that would allow us to explain the difference in the number of periods with PEP>PB and PEP>PPLS. We analyze then the averaged plasma parameters measured in the upstream region of the shocks and find significantly lower solar wind proton temperatures and magnetic field magnitude upstream of IP shocks in solar cycle 24 compared with those in solar cycle 23. These factors, together with the lower level of solar activity, may explain the lower particle intensities in solar cycle 24 and hence the fewer events with PEP>PB and PEP>PPLS.

  14. Geomagnetic storms of cycle 24 and their solar sources

    NASA Astrophysics Data System (ADS)

    Watari, Shinichi

    2017-05-01

    Solar activity of cycle 24 following the deep minimum between cycle 23 and cycle 24 is the weakest one since cycle 14 (1902-1913). Geomagnetic activity is also low in cycle 24. We show that this low geomagnetic activity is caused by the weak dawn-to-dusk solar wind electric field ( E d-d) and that the occurrence rate of E d-d > 5 mV/m decreased in the interval from 2013 to 2014. We picked up seventeen geomagnetic storms with the minimum Dst index of less than -100 nT and identified their solar sources in cycle 24 (2009-2015). It is shown that the relatively slow coronal mass ejections contributed to the geomagnetic storms in cycle 24.

  15. A review of the solar cycle length estimates

    NASA Astrophysics Data System (ADS)

    Benestad, R. E.

    2005-08-01

    New estimates of the solar cycle length are calculated from an up-to-date monthly sunspot record using a novel but mathematically rigorous method involving multiple regression, Fourier approximation, and analytical expressions for the first derivative based on calculus techniques. The sensitivity of the estimates to smoothing are examined and the analysis is used to identify possible systematic changes in the sun. The solar cycle length analysis indicates a pronounced change in the sun around 1900, before which the estimates fluctuate strongly and after which the estimates show little variability. There have been speculations about an association between the solar cycle length and Earth's climate, however, the solar cycle length analysis does not follow Earth's global mean surface temperature. A further comparison with the monthly sunspot number, cosmic galactic rays and 10.7 cm absolute radio flux since 1950 gives no indication of a systematic trend in the level of solar activity that can explain the most recent global warming.

  16. DMSP Auroral Charging at Solar Cycle 24 Maximum

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  17. DMSP Auroral Charging at Solar Cycle 24 Maximum

    NASA Technical Reports Server (NTRS)

    Chandler, Michael; Parker, Linda Neergaard; Minow, Joseph I.

    2013-01-01

    It has been well established that polar orbiting satellites can experience mild to severe auroral charging levels (on the order of a few hundred volts to few kilovolts negative frame potentials) during solar minimum conditions (Frooninckx and Sojka, 1992; Anderson and Koons, 1996; Anderson, 2012). These same studies have shown a strong reduction in charging during the rising and declining phases of the past few solar cycles with a nearly complete suppression of auroral charging at solar maximum. Recently, we have observed examples of high level charging during the recent approach to Solar Cycle 24 solar maximum conditions not unlike those reported by Frooninckx and Sojka (1992). These observations demonstrate that spacecraft operations during solar maximum cannot be considered safe from auroral charging when solar activity is low. We present a survey of auroral charging events experienced by the Defense Meteorological Satellite Program (DMSP) F16 satellite during Solar Cycle 24 maximum conditions. We summarize the auroral energetic particle environment and the conditions necessary for charging to occur in this environment, we describe how the lower than normal solar activity levels for Solar Cycle 24 maximum conditions are conducive to charging in polar orbits, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period.

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

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2012-01-01

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

  19. Variation of Solar, Interplanetary and Geomagnetic Parameters during Solar Cycles 21-24

    NASA Astrophysics Data System (ADS)

    Oh, Suyeon; Kim, Bogyeong

    2013-06-01

    The length of solar cycle 23 has been prolonged up to about 13 years. Many studies have speculated that the solar cycle 23/24 minimum will indicate the onset of a grand minimum of solar activity, such as the Maunder Minimum. We check the trends of solar (sunspot number, solar magnetic fields, total solar irradiance, solar radio flux, and frequency of solar X-ray flare), interplanetary (interplanetary magnetic field, solar wind and galactic cosmic ray intensity), and geomagnetic (Ap index) parameters (SIG parameters) during solar cycles 21-24. Most SIG parameters during the period of the solar cycle 23/24 minimum have remarkably low values. Since the 1970s, the space environment has been monitored by ground observatories and satellites. Such prevalently low values of SIG parameters have never been seen. We suggest that these unprecedented conditions of SIG parameters originate from the weakened solar magnetic fields. Meanwhile, the deep 23/24 solar cycle minimum might be the portent of a grand minimum in which the global mean temperature of the lower atmosphere is as low as in the period of Dalton or Maunder minimum.

  20. Development of Solar Activity Cycle 24: Some Comments

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.

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

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

    NASA Astrophysics Data System (ADS)

    Tlatov, A. G.

    2007-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Rušin, V.; Saniga, M.; Komžík, R.

    2014-10-01

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

  3. Forecasting the Peak of the Present Solar Activity Cycle

    NASA Astrophysics Data System (ADS)

    Hamid, Rabab; Marzouk, Beshir

    2016-07-01

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

  4. 25 MeV Solar Proton Events in Cycle 24 and Previous Cycles

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. New evidence for solar cycle variations at great distances

    NASA Technical Reports Server (NTRS)

    Venkatesan, D.; Balasubrahmanyan, V. K.

    1972-01-01

    Recent studies of solar planetary relationships are directed toward exploring how far out from the sun one could observe solar cycle variations. A positive solar Jovian relationship is suggested from a Chree superposed epoch study of the intensity of the great red spot of Jupiter over a period of about six solar cycles. The characteristic double maxima observed in the solar cycle variation is common to other observations of solar events in the photosphere, chromosphere, and corona; radio and corpuscular emissions from the sun; cosmic ray intensity and geomagnetic activity. The same method of analysis adopted for the study of luminosity changes of the planets Jupiter, Saturn, Uranus, and Neptune indicates that the fluctuations of luminosity follow the single maximum solar cycle represented by sunspot numbers. In conjunction with changes of upper atmospheric density and temperature, it is suggested that the extreme ultraviolet (EUV) emission from the sun may be connected with luminosity changes. A method of distinguishing between phenomena related to solar wind and those related to solar EUV is presented.

  6. Solar thermal organic rankine cycle for micro-generation

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  7. Weak ionization of the global ionosphere in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Shi, H.; Xiao, Z.; Zhang, D. H.

    2014-07-01

    Following prolonged and extremely quiet solar activity from 2008 to 2009, the 24th solar cycle started slowly. It has been almost 5 years since then. The measurement of ionospheric critical frequency (foF2) shows the fact that solar activity has been significantly lower in the first half of cycle 24, compared to the average levels of cycles 19 to 23; the data of global average total electron content (TEC) confirm that the global ionosphere around the cycle 24 peak is much more weakly ionized, in contrast to cycle 23. The weak ionization has been more notable since the year 2012, when both the ionosphere and solar activity were expected to be approaching their maximum level. The undersupply of solar extreme ultraviolet (EUV) irradiance somewhat continues after the 2008-2009 minimum, and is considered to be the main cause of the weak ionization. It further implies that the thermosphere and ionosphere in the first solar cycle of this millennium would probably differ from what we have learned from the previous cycles of the space age.

  8. Analysis of Sunspot Area over Two Solar Cycles

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  9. ANALYSIS OF SUNSPOT AREA OVER TWO SOLAR CYCLES

    SciTech Connect

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

    2013-06-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Solar Cycle Characteristics and Their Relationship with Dynamo Theory

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Solar Cycle 24 - A GOES Space Environment Monitor Perspective

    NASA Astrophysics Data System (ADS)

    Tilton, M.; Wilkinson, D. C.

    2015-12-01

    Our local star has had time for around 400 million solar activity cycles, but, the official tally only started 260 years ago when it was wisely decided to start with number one. Here at cycle 24 we have ways to observe solar activity effects that Richard Carrington never dreamed of. NOAA was an early adopter of space weather monitoring via satellite when the SMS-GOES mission began in 1974. This presentation uses those historical data to compare cycle 24 with the two preceding cycles. A variety of other space weather data and indices are thrown in for good measure.

  13. Data Assimilation Approach for Forecast of Solar Activity Cycles

    NASA Astrophysics Data System (ADS)

    Kitiashvili, Irina N.

    2016-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

    DeNolfo, G. A.; Yanasak, N. E.; Binns, W. R.; Cohen, C. M. S.; Cummings, A. C.; Davis, A. J.; George, J. S.; Hink. P. L.; Israel, M. H.; Lave, K.; hide

    2007-01-01

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

  16. Solar Cycle Spectral Irradiance Variation and Stratospheric Ozone

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Ahluwalia, H. S.

    2001-08-01

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

  18. Encore of the Bashful ballerina in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Virtanen, I. I.

    2009-04-01

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

  19. Trends and Solar Cycle Effects in Temperature Versus Altitude From the Halogen Occultation Experiment for the Mesosphere and Upper Stratosphere

    NASA Technical Reports Server (NTRS)

    Remsberg, Ellis E.

    2009-01-01

    Fourteen-year time series of mesospheric and upper stratospheric temperatures from the Halogen Occultation Experiment (HALOE) are analyzed and reported. The data have been binned according to ten-degree wide latitude zones from 40S to 40N and at 10 altitudes from 43 to 80 km-a total of 90 separate time series. Multiple linear regression (MLR) analysis techniques have been applied to those time series. This study focuses on resolving their 11-yr solar cycle (or SC-like) responses and their linear trend terms. Findings for T(z) from HALOE are compared directly with published results from ground-based Rayleigh lidar and rocketsonde measurements. SC-like responses from HALOE compare well with those from lidar station data at low latitudes. The cooling trends from HALOE also agree reasonably well with those from the lidar data for the concurrent decade. Cooling trends of the lower mesosphere from HALOE are not as large as those from rocketsondes and from lidar station time series of the previous two decades, presumably because the changes in the upper stratospheric ozone were near zero during the HALOE time period and did not affect those trends.

  20. Data Assimilation and Uncertainties in Early Solar Cycle Predictions

    NASA Astrophysics Data System (ADS)

    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

    NASA Astrophysics Data System (ADS)

    Dikpati, Mausumi

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Gruzdev, Aleksandr

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

  3. Trends and solar cycle effects in mesospheric ice clouds

    NASA Astrophysics Data System (ADS)

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

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

  4. Some problems in coupling solar activity to meteorological phenomena

    NASA Technical Reports Server (NTRS)

    Dessler, A. J.

    1975-01-01

    The development of a theory of coupling of solar activity to meteorological phenomena is hindered by the difficulties of devising a mechanism that can modify the behavior of the troposphere while employing only a negligible amount of energy compared with the energy necessary to drive the normal meteorological system, and determining how such a mechanism can effectively couple some relevant magnetospheric process into the troposphere in such a way as to influence the weather. A clue to the nature of the interaction between the weather and solar activity might be provided by the fact that most solar activity undergoes a definite 11-yr cycle, and meteorological phenomena undergo either no closely correlated variation, an 11-yr variation, or a 22-yr variation.

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

    NASA Astrophysics Data System (ADS)

    Lozytsky, V.; Efimenko, V.

    2012-12-01

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

  6. Minimal Magnetic States of the Sun and the Solar Wind: Implications for the Origin of the Slow Solar Wind

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; von Steiger, R.

    2017-09-01

    During the last decade it has been proposed that both the Sun and the solar wind have minimum magnetic states, lowest order levels of magnetism that underlie the 11-yr cycle as well as longer-term variability. Here we review the literature on basal magnetic states at the Sun and in the heliosphere and draw a connection between the two based on the recent deep 2008-2009 minimum between cycles 23 and 24. In particular, we consider the implications of the low solar activity during the recent minimum for the origin of the slow solar wind.

  7. The Total Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

    Dewitte, Steven; Nevens, Stijn

    2016-10-01

    We present the composite measurements of total solar irradiance (TSI) as measured by an ensemble of space instruments. The measurements of the individual instruments are put on a common absolute scale, and their quality is assessed by intercomparison. The composite time series is the average of all available measurements. From 1984 April to the present the TSI shows a variation in phase with the 11 yr solar cycle and no significant changes of the quiet-Sun level in between the three covered solar minima.

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

    SciTech Connect

    Jin, Chunlan; Wang, Jingxiu

    2015-06-20

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

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

    NASA Astrophysics Data System (ADS)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Pesnell, W. Dean

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Pesnell, W. Dean

    1993-01-01

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

  14. Solar Cycle in the Heliosphere and Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Bazilevskaya, Galina A.; Cliver, Edward W.; Kovaltsov, Gennady A.; Ling, Alan G.; Shea, M. A.; Smart, D. F.; Usoskin, Ilya G.

    2014-12-01

    Manifestations of the 11-year solar cycle and longer time-scale variability in the heliosphere and cosmic rays are considered. We briefly review the cyclic variability of such heliospheric parameters as solar wind speed and density and heliospheric magnetic field, open magnetic flux and latitude variations of the heliospheric current sheet. It is discussed whether the local in-situ observation near Earth can represent the global 3D heliospheric pattern. Variability of cosmic rays near Earth provides an indirect useful tool to study the heliosphere. We discuss details of the heliospheric modulation of galactic cosmic rays, as recorded at and near Earth, and their relation to the heliospheric conditions in the outer heliosphere. On the other hand, solar energetic particles can serve as probes for explosive phenomena on the Sun and conditions in the corona and inner heliosphere. The occurrence of major solar proton events depicts an overall tendency to follow the solar cycle but individual events may appear at different phases of the solar cycle, as defined by various factors. The solar cycle in the heliosphere and cosmic rays depicts a complex pattern which includes different processes and cannot be described by a simple correlation with sunspot number.

  15. Solar Cycle: Magnetized March to Equator

    NASA Image and Video Library

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

  16. Solar flux and its variations

    NASA Technical Reports Server (NTRS)

    Smith, E. V. P.; Gottlieb, D. M.

    1975-01-01

    Data are presented on the solar irradiance as derived from a number of sources. An attempt was made to bring these data onto a uniform scale. Summation of fluxes at all wavelengths yields a figure of 1357.826 for the solar constant. Estimates are made of the solar flux variations due to flares, active regions (slowly varying component), 27-day period, and the 11-yr cycle. Solar activity does not produce a significant variation in the value of the solar constant. Variations in the X-ray and EUV portions of the solar flux may be several orders of magnitude during solar activity, especially at times of major flares. It is established that these short wavelength flux enhancements cause significant changes in the terrestrial ionosphere.

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

    NASA Astrophysics Data System (ADS)

    Eter, Ahmad Adel

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Lukianova, R.

    2009-04-01

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

  19. Solar-Cycle Variations Observed by Helioseismology and Constraints on Solar Dynamo

    NASA Astrophysics Data System (ADS)

    Kosovichev, Alexander G.; Larson, Timothy P.; Guerrero, Gustavo; Pipin, Valery

    2017-08-01

    Helioseismology data from the SOHO and SDO, obtained in 1996-2017 for almost two solar cycles, provide a unique opportunity to investigate variations of the solar interior structure and dynamics, and link these variations to the current dynamo models and simulations. The solar oscillation frequencies and frequency splitting of medium-degree p- and f-modes, as well as helioseismic inversions have been used to analyze the differential rotation and global asphericity. By comparing the helioseismology results with the synoptic surface magnetic fields we identify characteristic changes associated the initiation and evolution of the solar cycles, 23 and 24. The observational results are compared with the current mean-field dynamo models and 3D MHD dynamo simulations. It is shown that the helioseismology inferences provide important constraints on the dynamics of the tachocline and near-surface shear layer, and also may explain the fundamental difference between the two solar cycles and detect the onset of the next cycle.

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

    NASA Technical Reports Server (NTRS)

    Webb, David F.; Howard, Russell A.

    1994-01-01

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

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

    SciTech Connect

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

    2015-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  3. Solar cycle variations in the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    SciTech Connect

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

    2014-11-01

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

  5. Solar cycle variation of thermospheric nitric oxide at solstice

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  6. Solar cycle variation of thermospheric nitric oxide at solstice

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  7. ENIGMA OF THE SOLAR CYCLE 4 STILL NOT RESOLVED

    SciTech Connect

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

    2011-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  9. Hubble Space Telescope solar cell module thermal cycle test

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  11. Connection between solar activity cycles and grand minima generation

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  12. 25 MeV solar proton events in Cycle 24 and previous cycles

    NASA Astrophysics Data System (ADS)

    Richardson, Ian G.; von Rosenvinge, Tycho T.; Cane, Hilary V.

    2017-08-01

    We summarize observations of around a thousand solar energetic particle (SEP) events since 1967 that include ∼25 MeV protons, made by various near-Earth spacecraft (IMPs 4, 5, 7, 8, ISEE 3, SOHO), that encompass Solar Cycle 20 to the current cycle (24). We also discuss recent observations of similar SEP events in Cycle 24 made by the STEREO spacecraft. The observations show, for example, that the time distribution of ∼25 MeV proton events varies from cycle to cycle. In particular, the time evolution of the SEP occurrence rate in Cycle 24 is strongly asymmetric between the northern and southern solar hemispheres, and tracks the sunspot number in each hemisphere, whereas Cycle 23 was more symmetric. There was also an absence of 25 MeV proton events during the solar minimum preceding Cycle 24 (other minima show occasional, often reasonably intense events). So far, events comparable to the exceptionally intense events detected in Cycles 22 and 23 have not been observed at Earth in Cycle 24, though Cycle 21 (the largest of the cycles considered here) also apparently lacked such events. We note a correlation between the rates of intense 25 MeV proton events and ;ground level enhancements; (GLEs) observed by neutron monitors, since 1967, and conclude that the number of ;official; GLEs (1) observed to date in Cycle 24 appears to be significantly lower than expected (5 to 7 ± 1) based on the rate of intense 25 MeV proton events in this cycle.

  13. A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

    SciTech Connect

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  15. Statistical pecularities of 24th cycle of solar activity

    NASA Astrophysics Data System (ADS)

    Efimenko, V.; Lozitsky, V.

    2016-06-01

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

  16. Solar cycles and their relationship to human disease and adaptability.

    PubMed

    Davis, George E; Lowell, Walter E

    2006-01-01

    In this paper, we show that 11-year solar cycle peaks predispose humans to disease, but also endow creativity and adaptability. We give several examples of diseases that are modulated by light and present evidence for an effect of intensity and variation in sunlight, primarily ultraviolet radiation (UVR), on the human genome. The birth dates of nearly 237,000 unique clients in the Maine Medicaid database collected from 1995 to 2004, inclusive, were related to solar cycle irradiance for the past seventy-one years, encompassing seven solar cycles. The sample was divided into four general categories of disease: mental/behavioral illnesses; metabolic diseases; autoimmune diseases; neoplasms. The birth months for those clients born in any given year were arranged in the form of a winter/summer ratio in order to more clearly appreciate the seasonality inherent in each disease category. Solar cycles were separated into chaotic (approximately three times as irradiant) or non-chaotic according to the Gutenberg-Richter power law and the uncertainty inherent in predicting solar storms. The results show that radiation peaks in solar cycles and particularly in chaotic solar cycles (CSCs) are associated with a higher incidence of mental disorders, suggesting the sensitivity of ectodermal embryonic tissues to UVR. Autoimmune diseases have intermediate sensitivity, while the neoplasms in the study, primarily of endoderm, appear suppressed by peak UVR intensity. The ratio of the number of clients born in CSC cycles to non-CSC cycles was highest for the more genetic mental diseases, like schizophrenia and bipolar disorder, but as that ratio decreased, the clients with diseases like multiple sclerosis and rheumatoid arthritis showed more environmental features manifested as a greater winter/summer birth month ratio that was significantly different than that of the average client in the whole data set. The paper presents evidence that latitude, e.g., variation in light, is an added

  17. A double magnetic solar cycle and dynamical systems

    NASA Astrophysics Data System (ADS)

    Popova, H.

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

  19. Solar neutron decay proton observations in cycle 21

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-02-01

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

  1. Solar rotation and the sunspot cycle

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Wilson, Robert M.

    1990-01-01

    Reexamination of the published sunspot rotation rates from Mount Wilson for the period from 1921 to 1982 suggests that the sun rotates more rapidly when there are fewer sunspots. This behavior is seen over the course of each cycle with the most rapid rotation usually observed at sunspot minimum. It is also seen in hemispheric differences with the southern hemisphere, having fewer spots, rotating more rapidly than the northern hemisphere. Furthermore, the rotation rate averaged over each cycle also shows that the sun rotates more rapidly during cycles with fewer sunspots and less sunspots area. This inverse correlation between sunspot area and rotation rate suggests that during the Maunder minimum the sun may have rotated slightly faster than is observed today.

  2. THREE-DIMENSIONAL EVOLUTION OF SOLAR WIND DURING SOLAR CYCLES 22-24

    SciTech Connect

    Manoharan, P. K.

    2012-06-01

    This paper presents an analysis of three-dimensional evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data used in this study have been obtained from the interplanetary scintillation (IPS) measurements made at the Ooty Radio Telescope, operating at 327 MHz. Results show that (1) on average, there was a downward trend in density turbulence from the maximum of cycle 22 to the deep minimum phase of cycle 23; (2) the scattering diameter of the corona around the Sun shrunk steadily toward the Sun, starting from 2003 to the smallest size at the deepest minimum, and it corresponded to a reduction of {approx}50% in the density turbulence between the maximum and minimum phases of cycle 23; (3) the latitudinal distribution of the solar wind speed was significantly different between the minima of cycles 22 and 23. At the minimum phase of solar cycle 22, when the underlying solar magnetic field was simple and nearly dipole in nature, the high-speed streams were observed from the poles to {approx}30 Degree-Sign latitudes in both hemispheres. In contrast, in the long-decay phase of cycle 23, the sources of the high-speed wind at both poles, in accordance with the weak polar fields, occupied narrow latitude belts from poles to {approx}60 Degree-Sign latitudes. Moreover, in agreement with the large amplitude of the heliospheric current sheet, the low-speed wind prevailed in the low- and mid-latitude regions of the heliosphere. (4) At the transition phase between cycles 23 and 24, the high levels of density and density turbulence were observed close to the heliospheric equator and the low-speed solar wind extended from the equatorial-to-mid-latitude regions. The above results in comparison with Ulysses and other in situ measurements suggest that the source of the solar wind has changed globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary

  3. Long term periodicity in solar wind velocity during the last three solar cycles

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.; Richardson, J. D.; Paularena, K. I.

    1995-01-01

    Solar wind measurements from the Pioneer 10, Pioneer 11, Voyager 2, IMP 8, and Pioneer Venus Orbiter (PVO) spacecraft were examined to search for long-term periodicities during the last three solar cycles. For the time of the last solar maximum, these measurements confirm the existence of the periodic 1.3-year enhancements in solar wind velocity reported by Richardson et al. (1994). For most of the preceding two solar cycles, long-term velocity enhancements occurred that were similar in structure but lacked the 1.3-year periodicity. It appears that long-term enhancements in solar wind velocity, with durations on the order of a few months to a year, are a common feature throughout the heliosphere.

  4. Coronal Hole Sources of Solar Wind Over ~Three Solar Activity Cycles

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Li, Y.; Arge, C. N.; Gazis, P. R.; Ulrich, R.

    2001-05-01

    Levine (Solar Physics v.79, 1982) was one of the first to use potential field source surface models of the coronal magnetic field, based on photospheric field observations, to infer the origins of the solar wind outflows reaching the ecliptic. Here we adopt and extend that approach to the last \\sim three solar cycles using the long archive of Mt. Wilson Observatory full-disk magnetograms. By tracing coronal field lines from within 20 degrees north and south of the source surface equator (at 2.5 Rs) to the Sun, we allow for variations due to the solar rotation axis tilt with respect to ecliptic north, and the still uncertain effects of the coronal/heliospheric currents on the divergence of coronal hole field lines. The results illustrate the modification of the polar hole source of near-ecliptic solar wind by the appearance of mid-latitude active regions in the rising phase of the solar cycle. As additional active regions emerge, midlatitude coronal holes associated with them rather abruptly take over as the dominant source through the solar maximum. While this result is not surprising, the long MWO record and continuous model display provide illuminating visualizations of coronal hole sources of the solar wind experienced by the planets through the solar cycle. Credence is lent to the results by favorable comparisons between average low heliolatitude magnetic field and solar wind velocity inferred from the source surface model and the Wang and Sheeley (Ap.J. v.355, 1990) approach, respectively, and observations near the earth. The alternate dominance of polar hole and active region sources, giving rise to differently phased interplanetary field and velocity cycles, explains how some trends in space weather are related to the solar magnetic cycle.

  5. Solar wind dynamics in the ascending phase of the solar cycle: five spacecraft observations

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Romero-Hernandez, E.

    2013-05-01

    We combined observations from: Helios 1 and 2, IMP-8, Voyager 1 and 2, from November 1977 to February 1978 (ascending phase of solar cycle 21). We identified five Corotating Interaction Regions, five Interplanetary Coronal Mass Ejections, and produced maps of large-scale features unifying and summarizing the data. We discuss their characteristics to illuminate some aspects of the solar wind dynamics, based on this unique data set, during the ascending phase of the cycle.

  6. A Statistical Test of Uniformity in Solar Cycle Indices

    NASA Technical Reports Server (NTRS)

    Hathaway David H.

    2012-01-01

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

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

    SciTech Connect

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

    2010-09-01

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

  8. Modeling the heliospheric current sheet: Solar cycle variations

    NASA Astrophysics Data System (ADS)

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

    2002-07-01

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

  9. Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations.

    PubMed

    Strugarek, A; Beaudoin, P; Charbonneau, P; Brun, A S; do Nascimento, J-D

    2017-07-14

    The magnetic fields of solar-type stars are observed to cycle over decadal periods-11 years in the case of the Sun. The fields originate in the turbulent convective layers of stars and have a complex dependency upon stellar rotation rate. We have performed a set of turbulent global simulations that exhibit magnetic cycles varying systematically with stellar rotation and luminosity. We find that the magnetic cycle period is inversely proportional to the Rossby number, which quantifies the influence of rotation on turbulent convection. The trend relies on a fundamentally nonlinear dynamo process and is compatible with the Sun's cycle and those of other solar-type stars. Copyright © 2017, American Association for the Advancement of Science.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  11. Solar Cycle Variations and Equatorial Oscillations: Modeling Study

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  12. BATSE flare observations in Solar Cycle 22

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  14. Phase Relationships of Solar Hemispheric Toroidal and Poloidal Cycles

    NASA Astrophysics Data System (ADS)

    Muraközy, J.

    2016-08-01

    The solar northern and southern hemispheres exhibit differences in their intensities and time profiles of the activity cycles. The time variation of these properties was studied in a previous article covering the data from Cycles 12-23. The hemispheric phase lags exhibited a characteristic variation: the leading role was exchanged between hemispheres every four cycles. The present work extends the investigation of this variation using the data of Staudacher and Schwabe in Cycles 1-4 and 7-10 as well as Spörer’s data in Cycle 11. The previously observed variation cannot be clearly recognized using the data of Staudacher, Schwabe, and Spörer. However, it is more interesting that the phase lags of the reversals of the magnetic fields at the poles follow the same variations as those of the hemispheric cycles in Cycles 12-23, i.e., one of the hemispheres leads in four cyles and the leading role jumps to the opposite hemisphere in the next four cycles. This means that this variation is a long-term property of the entire solar dynamo mechanism, for both the toroidal and poloidal fields, which hints at an unidentified component of the process responsible for the long-term memory.

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

    SciTech Connect

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

    2014-04-25

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

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

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, J.

    2015-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Scheiman, David A.

    1996-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    Zurbenko, Igor

    2014-01-01

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

  1. Skin cancer, irradiation, and sunspots: the solar cycle effect.

    PubMed

    Valachovic, Edward; Zurbenko, Igor

    2014-01-01

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

  2. OH Column Abundance Apparent Response to Solar Cycle 23

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  3. Improvement of Space Weather Forecasting in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Nitta, N.

    2014-12-01

    Solar Cycle 24 has not produced extreme space weather events at Earthcomparable to the Halloween 2003 events. However, there have been anumber of geomagnetic storms more intense than Dst of 100 nT as wellas several major solar energetic particle (SEP) events at Earth.Before predicting geomagnetic storms and radiation storms well inadvance, it is necessary to make a firm link of solar activity,notably coronal mass ejections (CMEs), with interplanetary CMEs(ICMEs) and shock waves. This cycle has benefitted from the SolarDynamics Observatory that provides uninterrupted and high-qualityfull-disk images at Earth, and the Solar Terrestrial RelationsObservatory that has observed CMEs away from the Sun-Earth line andunambiguously isolated those that were directed toward Earth. Thispresentation aims at evaluating how these observations have refinedour understanding of the origins of ICMEs and helped models reproducethe arrival times of the disturbances and the occurrence and magnitudeof SEP events. We also discuss what may be critically missing and yetessential for achieving useful predictions in the future. A review isgiven as to how the forecasts on the basis of solar and near-Sunobservations have fared against the actual ICMEs and shocks, and howmany of the latter have not been properly handled because of noobvious CMEs. A similar attempt is made for the occurrence andmagnitude of SEP events. It is important to critically analyze theinadequate forecasts (or just expectations) in terms of uncertaintiesfrom observations and modeling.

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

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Rightmire, Lisa

    2010-01-01

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

  5. Thermal stress cycling of GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Francis, Robert W.

    1987-01-01

    Thermal stress cycling was performed on gallium arsenide solar cells to investigate their electrical, mechanical, and structural integrity. Cells were cycled under low Earth orbit (LEO) simulated temperature conditions in vacuum. Cell evaluations consisted of power output values, spectral response, optical microscopy and ion microprobe mass analysis, and depth profiles on both front surface inter-grid areas and metallization contact grid lines. Cells were examined for degradation after 500, 5,000, 10,000 and 15,245 thermal cycles. No indication of performance degradation was found for any vendor's cell lot.

  6. Results of accelerated thermal cycle tests of solar cells modules

    NASA Technical Reports Server (NTRS)

    Berman, P.; Mueller, R.; Salama, M.; Yasui, R.

    1976-01-01

    Various candidate solar panel designs were evaluated, both theoretically and experimentally, with respect to their thermal cycling survival capability, and in particular with respect to an accelerated simulation of thermal cycles representative of Viking '75 mission requirements. The experimental results were obtained on 'mini-panels' thermally cycled in a newly installed automated test facility herein described. The resulting damage was analyzed physically and theoretically, and on the basis of these analyses the panel design was suitably modified to significantly improve its ability to withstand the thermal environment. These successful modifications demonstrate the value of the complementary theoretical-experimental approach adopted, and discussed in detail in this paper.

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

    SciTech Connect

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

    2009-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Dame, L.; Cugnet, D.

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  14. Observed Helicity of Active Regions in Solar Cycle 21

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  15. Solar powered Stirling cycle electrical generator

    NASA Technical Reports Server (NTRS)

    Shaltens, Richard K.

    1991-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Nuss, H. E.

    1980-01-01

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

  17. Evolution of sunspot properties during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Watson, F. T.; Fletcher, L.; Marshall, S.

    2011-09-01

    Context. 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. Aims: 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. Methods: 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 as well as corresponding information for the umbral areas detected within the sunspots, and track them through their evolution. Results: We find that the total visible umbral area is 20-40% of the total visible sunspot area regardless of the stage of the solar cycle. We also find that the number of sunspots observed follows the Solar Influences Data Centre international sunspot number with some interesting deviations. Finally, we use the magnetic information in our catalogue to study the long term variation of magnetic field strength within sunspot umbrae and find that it increases and decreases along with the sunspot number. However, if we were to assume a secular decrease as was reported in the Kitt Peak data and take into account sunspots throughout the whole solar cycle we would find the maximum umbral magnetic fields to be decreasing by 23.6 ± 3.9 Gauss per year, which is far less than has previously been observed by other studies (although measurements are only available for solar cycle 23). If we only look at the declining phase of cycle 23 we find the decrease in sunspot magnetic fields to

  18. Effects of solar cycle on auroral particle acceleration

    NASA Astrophysics Data System (ADS)

    Cattell, C. A.; Nguyen, T.; Temerin, M.; Lennartsson, W.; Peterson, W.

    We present the results of two studies designed to assess the effect of solar cycle on auroral particle acceleration processes. The first study is of data obtained from the S3-3 satellite at geocentric distances from 1.3 to 2.2 Re during solar minimum and the rising phase of the solar cycle. The S3-3 study included electrostatic shocks, ion beams and conics, and electron beams, but did not include ion composition. The second study is of data obtained by the ISEE-1 satellite when the ion mass spectrometer was operating in a special mode designed to study auroral ion distributions. This study covers geocentric distances from ˜2.5 to 7 Re during solar maximum and includes O+ and H+ beams and conics, and electrostatic shocks and low frequency turbulence. The S3-3 statistics for shocks with ion beams imply that the auroral parallel potential drop usually occurs above ˜2.2 Re at solar maximum, while the ISEE-1 observations suggest the potential drop, at solar maximum, may be located at ˜2.5 to 4 Re. The ISEE-1 beam observations (usually at energies less than or equal to 1 keV) imply that the potential drop is less, on average, for solar maximum than for solar minimum. Both data sets provide evidence for increased perpendicular acceleration of ions during solar maximum, associated with electrostatic shocks and enhanced low frequency turbulence. The ISEE-1 data show that the flux of upflowing O+ continues to increase as F10.7 increases from "low" to "high" solar maximum. These data also provide evidence that the ion two-stream instability is important in modifying the ion distributions. Most of these observations may be understood as being due to increased heating of the atmosphere during solar maximum which results in an increase in the H+ - O+ charge exchange altitude and an increase in the ionospheric density and temperature. Some effects, including the F10.7 dependence of the local time distribution of electrostatic shocks and the apparent decrease in the magnitude

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Svedin, Andreas

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

  1. Longitudinal Waves Drive the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    2000-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Liou, Kan; Wu, Chin-Chun

    2016-12-01

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

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

    SciTech Connect

    Telloni, Daniele; Antonucci, Ester; Carbone, Vincenzo; Lepreti, Fabio

    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. Central antarctic climate response to the solar cycle

    NASA Astrophysics Data System (ADS)

    Volobuev, D. M.

    2014-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Scheiman, David A.

    1997-01-01

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

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

    SciTech Connect

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

    1997-12-31

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

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Why are there fewer large SEP events this solar cycle?

    NASA Astrophysics Data System (ADS)

    Giacalone, J.; Mewaldt, R. A.

    2016-12-01

    There have been fewer large Solar Energetic Particle (SEP) events seen during the current solar cycle compared to the previous one. To understand this, we use a model for the acceleration of energetic protons at (individual) fast and strong interplanetary shocks, combined with remote observations of the speed of coronal mass ejections (CME) near the Sun, to estimate the total integrated flux of large SEP events at Earth throughout the past two solar cycles. Our results are compared with NOAA/GOES observations of large SEP events during this period. We find that the dearth of large SEP events in the current solar cycle is caused partly by there being fewer fast CMEs, and partly because the interplanetary magnetic field magnitude is weaker. A weaker magnetic field causes the particles to be accelerated more slowly; and during the time over which the shock moves from the Sun to 1 AU, the slower acceleration rate results in a lower intensity of high-energy particles. Our model is based on a solution to the diffusive shock acceleration theory applied to a spherically propagating shock. We use a diffusion coefficient that scales with the square of the heliocentric distance, so that it is very small near the Sun. Its value at 1AU is determined from observations of one particular large SEP event (DOY 302, 2003) seen during the well-known Halloween storm period of 2003. Comparison with this one event is also used to normalize our results. When convolved with the remotely observed speed distribution of many thousands of CMEs during the past two solar cycles, our model gives a reasonably close estimate of the observed total integrated flux of high-energy (>10 MeV) SEPs, despite its rather simple assumptions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. Comparison of Voyager Shocks in Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Ashmall, Justin; Richardson, John

    2005-08-01

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

  12. Solar Cycle Variation and Multipoint Studies of ICME Properties

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Altrock, Richard C.

    1997-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Pishkalo, M.

    2014-12-01

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

  15. Multidecadal Signal of Solar Variability in the Upper Troposphere During the 20th Century

    NASA Astrophysics Data System (ADS)

    Brönnimann, S.; Ewen, T.; Griesser, T.; Jenne, R.

    2006-08-01

    Studies based on data from the past 25 45 years show that irradiance changes related to the 11-yr solar cycle affect the circulation of the upper troposphere in the subtropics and midlatitudes. The signal has been interpreted as a northward displacement of the subtropical jet and the Ferrel cell with increasing solar irradiance. In model studies on the 11-yr solar signal this could be related to a weakening and at the same time broadening of the Hadley circulation initiated by stratospheric ozone anomalies. Other studies, focusing on the direct thermal effect at the Earth’s surface on multidecadal scales, suggest a strengthening of the Hadley circulation induced by an increased equator-to-pole temperature gradient. In this paper we analyse the solar signal in the upper troposphere since 1922, using statistical reconstructions based on historical upper-air data. This allows us to address the multidecadal variability of solar irradiance, which was supposedly large in the first part of the 20th century. Using a simple regression model we find a consistent signal on the 11-yr time scale which fits well with studies based on later data. We also find a significant multidecadal signal that is similar to the 11-yr signal, but somewhat stronger. We interpret this signal as a poleward shift of the subtropical jet and the Ferrel cell. Comparing the magnitude of the two signals could provide important information on the feedback mechanisms involved in the solar climate relationship with respect to the Hadley and Ferrel circulations. However, in view of the uncertainty in the solar irradiance reconstructions, such interpretations are not currently possible.

  16. Variations of ionospheric ionization and related solar fluxes during an intense solar cycle

    NASA Astrophysics Data System (ADS)

    Balan, N.; Bailey, G. J.; Jenkins, B.; Rao, P. B.; Moffett, R. J.

    1994-02-01

    Variations of ionospheric ionization (represented by ionospheric electron content (IEC)) and related solar fluxes with the 10.7-cm solar flux index (F10.7) are studied for the intense solar cycle 21 when F10.7 was as high as 367. The IEC data collected at several stations during 1980-1985, the solar EUV (50-1050 A) fluxes obtained from the EUV91 solar EUV flux model, and the measured values of Lyman alpha (1216 A) flux and He I (10,830 A) equivalent width (EW) are used for the study. It is shown that daily values of diurnal maximum IEC (IECmax) saturate (remain constant) when F10.7 (or its 81-day running average) exceeds a threshold (approximately 160-200) which depends slightly on season and latitude. Variations of the model values of the solar EUV fluxes reveal that when F10.7 exceeds the threshold: (1) the integrated solar EUV (50-1050 A) flux increases at a very low rate, and (2) the fluxes of the important (for thermospheric heating) chromospheric lines and intervals generally saturate (remain constant), while those of the coronal lines and intervals increase at a reduced rate. Lyman alpha flux and He I EW, which are used as input data in the solar EUV flux model, also increase at a very low rate when F10.7 exceeds the threshold. The saturation of ionospheric ionization, observed for high values of F10.7 during the last three solar cycles 19-21, is the result of the nonlinear variation of the solar EUV and Lyman alpha fluxes with F10.7. IECmax increases linearly with the integrated solar EUV flux, Lyman alpha flux and He I EW.

  17. Dual-peak solar cycle distribution of intense geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Gonzalez, W. D.; Gonzalez, A. L. C.; Tsurutani, B. T.

    1990-01-01

    This paper studies the features of the solar cycle distribution of intense storms (Dst) during cycles 20 and 21 (1965-1985). For these cycles, the distribution of intense storms (including moderate events for this time interval) in terms of Dst values below -50 nT, showed a dual-peak distribution, providing evidence for another enhancement of the intense storm distribution at the late ascending phase of the cycle. The origin of the dual-peak distribution of intense storms is associated with a similar dual-peak distribution obtained for large-amplitude and long-duration values of the negative Bz component of the IMF, computed for the interval 1970-1981.

  18. The onset of the solar active cycle 22

    NASA Technical Reports Server (NTRS)

    Ahluwalia, H. S.

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Miroshnichenko, Leonty I.; Fang, Cheng

    2015-07-01

    We present a study of seven large solar proton events in the current solar cycle 24 (from 2009 January up to the current date). They were recorded by the GOES spacecraft with the highest proton fluxes being over 200 pfu for energies >10 MeV. In situ particle measurements show that: (1) The profiles of the proton fluxes are highly dependent on the locations of their solar sources, namely flares or coronal mass ejections (CMEs), which confirms the “heliolongitude rules” associated with solar energetic particle fluxes; (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; and (3) The time differences between the SPR and the flare peak are also dependent on the locations of the solar active regions. The results tend to support the scenario of proton acceleration by the CME-driven shock, even though there exists a possibility of particle acceleration at the flare site, with subsequent perpendicular diffusion of accelerated particles in the interplanetary magnetic field. We derive the integral time-of-maximum spectra of solar protons in two forms: a single power-law distribution and a power law roll-over with an exponential tail. It is found that the unique ground level enhancement that occurred in the event on 2012 May 17 displays the hardest spectrum and the largest roll-over energy which may explain why this event could extend to relativistic energies. Supported by the National Natural Science Foundation of China.

  20. Babcock Leighton models of the solar cycle: Questions and issues

    NASA Astrophysics Data System (ADS)

    Charbonneau, Paul

    This paper is a review of our current state of understanding of dynamo models of the solar cycle based on the Babcock-Leighton mechanism of poloidal field regeneration by the decay of bipolar active regions. It is organized in the form of "point and counterpoint" discussion of ten issues or topics of contention to be found in the recent literature on these dynamo models. These go from similarities and differences with dynamo models based on mean-field electrodynamics, the role of meridional circulation in setting the predicted form of the sunspot butterfly diagram, constraints brought about by light element abundances, non-linear magnetic backreaction on the driving flows, up to the use of Babcock-Leighton models for predicting solar cycle amplitudes.

  1. The South Atlantic Anomaly throughout the solar cycle

    NASA Astrophysics Data System (ADS)

    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

  2. Ground level enhancements of cosmic rays in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Kravtsova, M. V.; Sdobnov, V. E.

    2017-07-01

    Using data from ground-based observations of cosmic rays (CRs) on the worldwide network of stations and spacecraft, we have investigated the proton spectra and the CR anisotropy during the ground level enhancements of CRs on May 17, 2012 (GLE71) and January 6, 2014 (GLE72) occurred in solar cycle 24 by the spectrographic global survey method. We provide the CR rigidity spectra and the relative changes in the intensity of CRs with a rigidity of 2 GV in the solar-ecliptic geocentric coordinate system in specific periods of these events. We show that the proton acceleration during GLE71 and GLE72 occurred up to rigidities R 2.3-2.5 GV, while the differential rigidity spectra of solar CRs are described neither by a power nor by an exponential function of particle rigidity. At the times of the events considered the Earth was in a loop-like structure of the interplanetary magnetic field.

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

    NASA Astrophysics Data System (ADS)

    Khalifa, H. E.; Melikian, G.

    1982-07-01

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

  4. SOLAR-CYCLE VARIATION OF SOUND SPEED NEAR THE SOLAR SURFACE

    SciTech Connect

    Rabello-Soares, M. C.

    2012-02-01

    We present evidence that the sound-speed variation with solar activity has a two-layer configuration, similar to the one observed below an active region, which consists of a negative layer near the solar surface and a positive one in the layer immediately below the first one. Frequency differences between the activity minimum and maximum of solar cycle 23, obtained applying global helioseismology to the Michelson Doppler Imager on board the Solar and Heliospheric Observatory, is used to determine the sound-speed variation from below the base of the convection zone to a few Mm below the solar surface. We find that the sound speed at solar maximum is smaller than at solar minimum at the limit of our determination (5.5 Mm). The min-to-max difference decreases in absolute values until {approx}7 Mm. At larger depths, the sound speed at solar maximum is larger than at solar minimum and the difference increases with depth until {approx}10 Mm. At this depth, the relative difference ({delta}c{sup 2}/c{sup 2}) is less than half of the value observed at the lowest depth determination. At deeper layers, it slowly decreases with depth until there is no difference between maximum and minimum activity.

  5. Design and fabrication of brayton cycle solar heat receiver

    NASA Technical Reports Server (NTRS)

    Mendelson, I.

    1971-01-01

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

  6. Solar cycle variation of large-scale coronal structures

    NASA Technical Reports Server (NTRS)

    Antonucci, E.; Duvall, T. L.

    1974-01-01

    A green line intensity variation is associated with the interplanetary and photospheric magnetic sector structure. This effect depends on the solar cycle and occurs with the same amplitude in the latitude range 60 deg N - 60 deg S. Extended longitudinal coronal structures are suggested, which indicate the existence of closed magnetic field lines over the neutral line, separating adjacent regions of opposite polarities on the photospheric surface.

  7. Drought over Seoul and Its Association with Solar Cycles

    NASA Astrophysics Data System (ADS)

    Park, Jong-Hyeok; Chang, Heon-Young

    2013-12-01

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

  8. Solar hydrogen production with cerium oxides thermochemical cycle

    NASA Astrophysics Data System (ADS)

    Binotti, Marco; Di Marcoberardino, Gioele; Biassoni, Mauro; Manzolini, Giampaolo

    2017-06-01

    This paper discusses the hydrogen production using a solar driven thermochemical cycle. The thermochemical cycle is based on nonstoichiometric cerium oxides redox and the solar concentration system is a solar dish. Detailed optical and redox models were developed to optimize the hydrogen production performance as function of several design parameters (i.e. concentration ratio, reactor pressures and temperatures) The efficiency of the considered technology is compared against two commercially available technologies namely PV + electrolyzer and Dish Stirling + electrolyzer. Results show that solar-to-fuel efficiency of 21.2% can be achieved at design condition assuming a concentration ratio around 5000, reduction and oxidation temperatures of 1500°C and 1275 °C. When moving to annual performance, the annual yield of the considered approach can be as high as 16.7% which is about 43% higher than the best competitive technology. The higher performance implies that higher installation costs around 40% can be accepted for the innovative concept to achieve the same cost of hydrogen.

  9. Coronal mass ejection activity during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Nunes, Steven; Howard, Russell A.

    2003-09-01

    We studied the solar cycle varition of various properties of coronal mass ejections (CMEs), such as daily CME rate, mean and median speeds, and the latitude of solar sources for cycle 23 (1996-2002). We find that (1) there is an order of magnitude increase in CME rate from the solar minimum (0.5/day) to maximum (6/day), (2) the maximum rate is significantly higher than previous estimates, (3) the mean and median speeds of CMEs also increase from minimum to maximum by a factor of 2, (4) the number of metric type II bursts (summed over CR) tracks CME rate, but the CME speed seems to be only of secondary importance, (5) for type II bursts originating farther from the Sun the CME speed is important, (6) the latitude distribution of CMEs separate the prominence-associated (high-latitude) and active-region associated CMEs, and (7) the rate of high-latitude CMEs shows north-south asymmetry and the cessation eruptions in the north and south roughly mark the polarity reversals. We compared the rates of the fast-and-wide CMEs, major solar flares, interplanetary (IP) shocks, long-wavelength type II bursts and large SEP events. This comparison revealed that the number of major flares is generally too large compared to all the other numbers. In other words, fast-and-wide CMEs, long-wavelength type II bursts, large SEP events, and IP shocks have a close physical relationship.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  11. Developing a Solar Magnetic Catalog Spanning Four Cycles

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 6,885 unique objects (detected and tracked) belonging to four separate solar cycles (21-24).

  12. Jovian Northern Ethane Aurora and the Solar Cycle

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  14. Solar cycle-dependent helicity transport by magnetic clouds

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Tindale, E.; Chapman, S. C.

    2016-06-01

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

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

    SciTech Connect

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

    2010-06-10

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

  17. Characteristics of the 23 Cycle of Solar Activity

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Tamara

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

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

    NASA Astrophysics Data System (ADS)

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

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

  19. A new method for forecasting the solar cycle descent time

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The prediction of an extended solar minimum is extremely important because of the severity of its impact on the near-earth space. Here, we present a new method for predicting the descent time of the forthcoming solar cycle (SC); the method is based on the estimation of the Shannon entropy. We use the daily and monthly smoothed international sunspot number. For each nth SC, we compute the parameter [Tpre]n by using information on the descent and ascent times of the n - 3th and nth SCs, respectively. We find that [Tpre] of nth SC and entropy can be effectively used to predict the descent time of the n + 2th SC. The correlation coefficient between [Td]n+2 - [Tpre]n and [E]n is found to be 0.95. Using these parameters the prediction model is developed. Solar magnetic field and F10.7 flux data are available for SCs 21-22 and 19-23, respectively, and they are also utilized to get estimates of the Shannon entropy. It is found that the Shannon entropy, a measure of randomness inherent in the SC, is reflected well in the various proxies of the solar activity (viz sunspot, magnetic field, F10.7 flux). The applicability and accuracy of the prediction model equation is verified by way of association of least entropy values with the Dalton minimum. The prediction model equation also provides possible criteria for the occurrence of unusually longer solar minima.

  20. Recurrence quantification analysis of two solar cycle indices

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

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

    SciTech Connect

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

    2014-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  3. Towards better constrained models of the solar magnetic cycle

    NASA Astrophysics Data System (ADS)

    Munoz-Jaramillo, Andres

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

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

    PubMed

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

    2016-04-05

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

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

    PubMed Central

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

    2016-01-01

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

  7. Understanding Activity Cycles of Solar Type Stars with Kepler

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

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

    PubMed

    Smart, D F; Shea, M A

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  10. A new simple dynamo model for solar activity cycle

    NASA Astrophysics Data System (ADS)

    Yokoi, Nobumitsu; Schmitt, Dieter

    2015-04-01

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

  11. A Complete Catalogue of High-Speed Solar Wind Streams during Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Xystouris, G.; Sigala, E.; Mavromichalaki, H.

    2014-03-01

    High-speed solar wind streams (HSSWSs) are ejected from the Sun and travel into the interplanetary space. Because of their high speed, they carry out energetic particles such as protons and heavy ions, which leads to an increase in the mean interplanetary magnetic field (IMF). Since the Earth is in the path of those streams, Earth's magnetosphere interacts with the disturbed magnetic field, leading to a significant radiation-induced degradation of technological systems. These interactions provide an enhanced energy transfer from the solar wind/IMF system into the Earth's magnetosphere and initiate geomagnetic disturbances that may have a possible impact on human health. Solar cycle 23 was a particularly unusual cycle with many energetic phenomena during its descending phase and also had an extended minimum. We have identified and catalogued the HSSWSs of this cycle and determined their characteristics, such as their maximum velocity, beginning and ending time, duration, and possible sources. We identified 710 HSSWSs and compared them with the corresponding characteristics of the streams of previous solar cycles. For first time, we used the CME data to study the stream sources, which led to useful results for the monitoring and forecasting of space weather effects.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

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

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

    PubMed

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

    2002-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Shea, M. A.

    2003-01-01

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

  17. Effects of solar cycle 24 activity on WAAS navigation

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  19. Climate Sensitivity and Solar Cycle Response in Climate Models

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  20. Solar Cycle Variability in New Merge Satellite Ozone Datasets

    NASA Astrophysics Data System (ADS)

    Kuchar, A.; Pisoft, P.

    2014-12-01

    Studies using coupled chemistry climate model simulations of the solar cycle in the ozone field reveal agreement with the observed "double-peaked" ozone anomaly in the original satellite observations represented by SBUV(/2), HALOE and SAGE datasets. The motivation of our analysis is to examine whether the solar signal in the last generation of reanalyzed datasets (i.e. MERRA and ERA-INTERIM) is consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. Since an analysis of the solar cycle response requires long-term and temporal homogeneous time series of the ozone profile and no single satellite instrument has covered the entire period since 1984, satellite measurements in our study are represented by new merged satellite ozone datasets, i.e. GOZCARDS, SBUV MOD and SWOOSH datasets. The results of the presented study are based on the attribution analysis using multiple nonlinear techniques besides traditional linear approach based on the multiple linear models. The study results are supplemented by a frequency analysis using the pseudo-2D wavelet transform algorithms.

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

    SciTech Connect

    2011-12-19

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

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

    NASA Astrophysics Data System (ADS)

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

    1999-05-01

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

  3. Kuramoto Model with Non-symmetric Coupling Reconstructs Variations of the Solar-Cycle Period

    NASA Astrophysics Data System (ADS)

    Blanter, E.; Le Mouël, J.-L.; Shnirman, M.; Courtillot, V.

    2016-03-01

    We apply a Kuramoto model with two non-linear, coupled oscillators to the simultaneous reconstruction of the phase difference of the two oscillators and instantaneous period (or length) of the solar cycle. The two long series of sunspot numbers [RI] and aa geomagnetic indices are considered as proxies of the toroidal and poloidal components of the solar magnetic field, respectively. Variations in the length of the solar cycle are successfully reconstructed when an asymmetry between coupling coefficients is introduced, corresponding to an asymmetry of the αΩ-mechanisms of solar magnetic-field generation. Application of the Kuramoto model to solar indices and comparison with synthetic data series shows the important role of synchronization in allowing one to estimate solar-cycle length. The Kuramoto model reconstruction reveals a {≈} 30 - 33 year (three solar cycles) quasi-periodicity and the influence of quasi-biennial oscillations present in the aa-index on the determination of solar-cycle length.

  4. HEMISPHERIC ASYMMETRIES IN THE POLAR SOLAR WIND OBSERVED BY ULYSSES NEAR THE MINIMA OF SOLAR CYCLES 22 AND 23

    SciTech Connect

    Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; McComas, D. J.; Pogorelov, N. V.

    2013-05-10

    We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric asymmetries in several parameters, most notably {approx}15%-30% south-to-north differences in averages for the solar wind density, mass flux, dynamic pressure, and energy flux and the radial and total IMF magnitudes. These differences were driven by relatively larger, more variable solar wind density and radial IMF between {approx}36 Degree-Sign S-60 Degree-Sign S during the declining phase of solar cycles 22 and 23. These observations indicate either a hemispheric asymmetry in the PCH output during the declining and minimum phase of solar cycles 22 and 23 with the southern hemisphere being more active than its northern counterpart, or a solar cycle effect where the PCH output in both hemispheres is enhanced during periods of higher solar activity. We also report a strong linear correlation between these solar wind and IMF parameters, including the periods of enhanced PCH output, that highlight the connection between the solar wind mass and energy output and the Sun's magnetic field. That these enhancements were not matched by similar sized variations in solar wind speed points to the mass and energy responsible for these increases being added to the solar wind while its flow was subsonic.

  5. Solar Cycle Variations of Fe-rich SEP Events

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    SciTech Connect

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

    1983-01-01

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

  7. Detection of the climate response to the solar cycle

    SciTech Connect

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

    1996-09-15

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  9. Solar photospheric network properties and their cycle variation

    SciTech Connect

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

    2014-11-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  11. Satellite Measurements of Middle Atmospheric Impacts by Solar Proton Events in Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Jackman, C.; Labow, G.; DeLand, M.; Fleming, E.; Sinnhuber, M.; Russell, J.

    2005-01-01

    Solar proton events (SPEs) are known to have caused changes in constituents in the Earth's neutral polar middle atmosphere in the most recent solar maximum period (solar cycle 23). The highly energetic protons produced ionizations, excitations, dissociations, and dissociative ionizations of the background constituents in the polar cap regions (greater than 60 degrees geomagnetic latitude), which led to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HOx increases led to short-lived ozone decreases in the polar mesosphere and upper stratosphere due to the short lifetimes of the HOx constituents. Polar middle mesospheric ozone decreases greater than 50% were observed and computed to last for hours to days due to the enhanced HOx. The NOy increases led to long-lived polar stratospheric ozone changes because of the long lifetime of the NOy family in this region. Upper stratospheric ozone decreases of greater than 10% were computed to last for several months past the solar events in the winter polar regions because of the enhanced NOy. Solar cycle 23 was especially replete with SPEs and huge fluxes of high energy protons occurred in July and November 2000, September and November 2001, April 2002, October 2003, and January 2005. Smaller, but still substantial, proton fluxes impacted the Earth during other months in this cycle. Observations by the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments along with GSFC 2D Model predictions will be shown in this talk.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  13. Study of Distribution and Asymmetry of Solar Active Prominences during Solar Cycle 23

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    In this article we present the results of a study of the spatial distribution and asymmetry of solar active prominences (SAP) for the period 1996 through 2007 (solar cycle 23). For more meaningful statistical analysis we analyzed the distribution and asymmetry of SAP in two subdivisions viz. Group1 (ADF, APR, DSF, CRN, CAP) and Group2 (AFS, ASR, BSD, BSL, DSD, SPY, LPS). The North - South (N - S) latitudinal distribution shows that the SAP events are most prolific in the 21° to 30° slice in the Northern and Southern Hemispheres; the East - West (E - W) longitudinal distribution study shows that the SAP events are most prolific (best observable) in the 81° to 90° slice in the Eastern and Western Hemispheres. It was found that the SAP activity during this cycle is low compared to previous solar cycles. The present study indicates that during the rising phase of the cycle the number of SAP events are roughly equal in the Northern and Southern Hemispheres. However, activity in the Southern Hemisphere has been dominant since 1999. Our statistical study shows that the N - S asymmetry is more significant then the E - W asymmetry.

  14. On the Reduced Geoeffectiveness of Solar Cycle 24: A Moderate Storm Perspective

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  15. On the Reduced Geoeffectiveness of Solar Cycle 24: A Moderate Storm Perspective

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  16. Evidence of solar induced cycles of high seismic activity

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  18. Variation of solar oscillation frequencies in solar cycle 23 and their relation to sunspot area and number

    NASA Astrophysics Data System (ADS)

    Jain, R.; Tripathy, S. C.; Watson, F. T.; Fletcher, L.; Jain, K.; Hill, F.

    2012-09-01

    Aims: Studying the long term evolution of the solar acoustic oscillations is necessary for understanding how the large-scale solar dynamo operates. In particular, an understanding of the solar cycle variation in the frequencies of solar oscillations can provide a powerful diagnostic tool for constraining various dynamo models. In this work, we report the temporal evolution of solar oscillations for the solar cycle 23, and correlate with solar magnetic activity indices. Methods: We use solar oscillation frequencies obtained from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory, correlate them with the sunspot number provided by the international sunspot number, RI, and compare them with the sunspot number calculated with the Sunspot Tracking And Recognition Algorithm (STARA). Results: We find that the mean frequency shifts correlate very well with the sunspot numbers obtained from two different datasets. We also find a hysteresis-type behaviour for the STARA sunspot area and mean magnetic field strength for the different phases of the solar cycle. The increase in solar oscillation frequencies precedes slightly the increase in total sunspot area and the mean magnetic field strength for the solar cycle 23. We briefly discuss the cyclic behaviour in the context of p-mode frequencies.

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

    NASA Astrophysics Data System (ADS)

    Mikhalchuk, V. V.

    2014-10-01

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

  20. The significant solar proton events in 20th solar cycle for the period October 1964 to March 1970

    NASA Technical Reports Server (NTRS)

    Atwell, W.

    1972-01-01

    Solar proton data are presented from observations by the Explorer 21, 28, 34 and 41 satellites. The NASA Solar Particle Alert Network (SPAN) solar optical and radio frequency data for the period May 1967 to March 1970 are associated with the proton events observed by the Explorer 34 and 41 satellites; however, missing data are supplemented with data recorded at other international observatories. From a radiation hazard standpoint, NASA is concerned with solar proton events of the order of 10 to the 8th power proton/sq cm. Radiation dose data are presented for some of the large proton events that have occurred thus far in the 20th solar cycle and are compared with some of the large proton events of the 19th solar cycle. Finally, the results of a simple parametric correlation study are presented for both the 19th and 20th solar cycles.

  1. High-Energy Solar Particle Events in Cycle 24

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  2. High-Energy Solar Particle Events in Cycle 24

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  3. Cycle 23, the first of weak solar cycles series and the serious implications on some Sun-Earth connections

    NASA Astrophysics Data System (ADS)

    Yousef, Shahinaz

    2003-09-01

    Solar cycle 23 is not a normal sunspot cycle, but is the first of a series of 2-4 successive weak cycles. Such weak mainly long duration cycles occurred in 1798-1833 and 1878-1922. Faster rotational rates were measured at the beginning of the period of weak cycles implying a drop in solar irradiance. It is anticipated that right now increased solar rotational rates are going in the outer and inner layers of the Sun. Some of the implications of entering a period of weak 12 yr. solar cycles on the Earth were found from the previous two periods and can be reflected into the future, e.g. drops in global air and sea surface temperatures, sudden rises of equatorial African lakes, increased frequencies of El Ninos, hurricanes and wide spread flood-drought hazards. Drop in solar irradiance, UV and X-rays fluxes, solar wind and increased invasion of galactic cosmic rays. Among the effects of the present weak solar cycles will be delayed rise in sea level and a hope for the closure of the ozone and God knows best.

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

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

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

  5. SOLAR CYCLE VARIATION OF SOUND SPEED INSIDE THE SUN

    SciTech Connect

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

    2012-08-10

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

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

    PubMed

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

    2011-06-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  8. Wavelength Dependence of Solar Rotation and Solar Cycle UV Irradiance Variations

    NASA Technical Reports Server (NTRS)

    London, Julius; Rottman, Gary J.

    1990-01-01

    It is shown that for the 5-year period 1982 to 1987 the solar irradiance decrease is estimated to be about 5 to 7 percent over the spectral interval 195 to 225 nm. This change becomes progressively smaller with increasing wavelength. For the 2-1/3 year period, January 1987 to April 1989, the irradiance increases about 6 percent at 195 to 205 nm and about 2 percent between 215 to 250 nm. Both 27-day and 13.5-day relative amplitudes peak at the time near solar maximum (1982) but remain comparatively small between 1983 and the onset of solar cycle 22. An average 280 day oscillation is noted for wavelengths up to 230 nm. No physical mechanism is offered for this variation.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  10. Periodicities in solar wind-magnetosphere coupling functions and geomagnetic activity during the past solar cycles

    NASA Astrophysics Data System (ADS)

    Andriyas, T.; Andriyas, S.

    2017-09-01

    In this paper, we study the solar-terrestrial relation through the wavelet analysis. We report periodicities common between multiple solar wind coupling functions and geomagnetic indices during five solar cycles and also and the strength of this correspondence. The Dst (found to be most predictable in Newell et al., J. Geophys. Res. Space Phys. 112(A1):A01206, 2007) and AL (least predictable in Newell et al., J. Geophys. Res. Space Phys. 112(A1):A01206, 2007) indices are used for this purpose. During the years 1966-2016 (which includes five solar cycles 20, 21, 22, 23, and 24), prominent periodicities ≤720 days with power above 95% confidence level were found to occur around 27, 182, 385, and 648 days in the Dst index while those in the AL index were found in bands around 27, 187, and 472 days. Ten solar wind coupling functions were then used to find periodicities common with the indices. All the coupling functions had significant power in bands centered around 27, 280, and 648 days while powers in fluctuations around 182, 385, and 472 days were only found in some coupling functions. All the drivers and their variants had power above the significant level in the 280-288 days band, which was absent in the Dst and AL indices. The normalized scale averaged spectral power around the common periods in the coupling functions and the indices indicated that the coupling functions most correlated with the Dst index were the Newell (27 and 385 days), Wygant (182 days), and Scurry-Russell and Boynton (648 days) functions. An absence of common power between the coupling functions and the Dst index around the annual periodicity was noted during the even solar cycles. A similar analysis for the AL index indicated that Newell (27 days), Rectified (187 days), and Boynton (472 days) were the most correlated functions. It was also found that the correlation numbers were relatively weaker for the AL index, specially for the 187 day periodicity. It is concluded that as the two

  11. Solar-cycle variations of the internetwork magnetic field

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Ricort, G.

    2015-10-01

    Context. The quiet Sun exhibits a rich and complex magnetic structuring that is still not fully resolved or understood. Aims: We intend to contribute to the debate about the origin of the internetwork magnetic fields and whether or not they are related to the global solar dynamo. Methods: We analyzed center-to-limb polarization measurements obtained with the SOT/SP spectropolarimeter onboard the Hinode satellite outside active regions in 2007 and 2013, that is, at a minimum and a maximum of the solar cycle, respectively. We examined 10'' × 10'' maps of the unsigned circular and linear polarization in the FeI 630.25 nm line in regions located away from network elements. The maps were corrected for bias and focus variations between the two data sets. Then we applied a Fourier spectral analysis to examine wether the spatial structuring of the internetwork magnetic fields shows significant differences between the minimum and maximum of the cycle. Results: Neither the mean values of the unsigned circular and linear polarizations in the selected 10'' × 10'' maps nor their spatial fluctuation power spectra show significant center-to-limb variations. For the unsigned circular polarization the power of the spatial fluctuations is lower in 2013 than in 2007, but the spectral slope is unchanged. The linear polarization spectra show no significant differences in 2013 and 2007, but the spectrum of 2013 is more strongly affected by noise. Conclusions: The small-scale magnetic structuring in the internetwork is different in our 2013 and 2007 data. Surprisingly, we find a lower spatial fluctuation power at the solar maximum in the internetwork magnetic structuring. This indicates some complex interactions between the small-scale magnetic structures in the quiet Sun and the global dynamo, as predicted by recent numerical simulations. This result has to be confirmed by further statistical studies with larger data sets.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  13. Fast and robust segmentation of solar EUV images: algorithm and results for solar cycle 23

    NASA Astrophysics Data System (ADS)

    Barra, V.; Delouille, V.; Kretzschmar, M.; Hochedez, J.-F.

    2009-10-01

    Context: The study of the variability of the solar corona and the monitoring of coronal holes, quiet sun and active regions are of great importance in astrophysics as well as for space weather and space climate applications. Aims: In a previous work, we presented the spatial possibilistic clustering algorithm (SPoCA). This is a multi-channel unsupervised spatially-constrained fuzzy clustering method that automatically segments solar extreme ultraviolet (EUV) images into regions of interest. The results we reported on SoHO-EIT images taken from February 1997 to May 2005 were consistent with previous knowledge in terms of both areas and intensity estimations. However, they presented some artifacts due to the method itself. Methods: Herein, we propose a new algorithm, based on SPoCA, that removes these artifacts. We focus on two points: the definition of an optimal clustering with respect to the regions of interest, and the accurate definition of the cluster edges. We moreover propose methodological extensions to this method, and we illustrate these extensions with the automatic tracking of active regions. Results: The much improved algorithm can decompose the whole set of EIT solar images over the 23rd solar cycle into regions that can clearly be identified as quiet sun, coronal hole and active region. The variations of the parameters resulting from the segmentation, i.e. the area, mean intensity, and relative contribution to the solar irradiance, are consistent with previous results and thus validate the decomposition. Furthermore, we find indications for a small variation of the mean intensity of each region in correlation with the solar cycle. Conclusions: The method is generic enough to allow the introduction of other channels or data. New applications are now expected, e.g. related to SDO-AIA data.

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

    NASA Astrophysics Data System (ADS)

    Li, Yunfei

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

  15. Solar cycle dependence of ion cyclotron wave frequencies

    NASA Astrophysics Data System (ADS)

    Lessard, Marc R.; Lindgren, Erik A.; Engebretson, Mark J.; Weaver, Carol

    2015-06-01

    Electromagnetic ion cyclotron (EMIC) waves have been studied for decades, though remain a fundamentally important topic in heliospheric physics. The connection of EMIC waves to the scattering of energetic particles from Earth's radiation belts is one of many topics that motivate the need for a deeper understanding of characteristics and occurrence distributions of the waves. In this study, we show that EMIC wave frequencies, as observed at Halley Station in Antarctica from 2008 through 2012, increase by approximately 60% from a minimum in 2009 to the end of 2012. Assuming that these waves are excited in the vicinity of the plasmapause, the change in Kp in going from solar minimum to near solar maximum would drive increased plasmapause erosion, potentially shifting the generation region of the EMIC to lower L and resulting in the higher frequencies. A numerical estimate of the change in plasmapause location, however, implies that it is not enough to account for the shift in EMIC frequencies that are observed at Halley Station. Another possible explanation for the frequency shift, however, is that the relative density of heavier ions in the magnetosphere (that would be associated with increased solar activity) could account for the change in frequencies. In terms of effects on radiation belt dynamics, the shift to higher frequencies tends to mean that these waves will interact with less energetic electrons, although the details involved in this process are complex and depend on the specific plasma and gyrofrequencies of all populations, including electrons. In addition, the change in location of the generation region to lower L shells means that the waves will have access to higher number fluxes of resonant electrons. Finally, we show that a sunlit ionosphere can inhibit ground observations of EMIC waves with frequencies higher than ˜0.5 Hz and note that the effect likely has resulted in an underestimate of the solar-cycle-driven frequency changes described here.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko

    2016-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Lean, J.; Foukal, P.

    1990-01-01

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

  2. Thermal stress cycling of GaAs solar cells

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  3. Thermal stress cycling of GaAs solar cells

    NASA Astrophysics Data System (ADS)

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

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

  4. Temporal changes in the frequencies of the solar p-mode oscillations during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Rhodes, E. J.; Reiter, J.; Schou, J.; Larson, T.; Scherrer, P.; Brooks, J.; McFaddin, P.; Miller, B.; Rodriguez, J.; Yoo, J.

    2011-08-01

    We present a study of the temporal changes in the sensitivities of the frequencies of the solar p-mode oscillations to corresponding changes in the levels of solar activity during Solar Cycle 23. From MDI and GONG++ full-disk Dopplergram three-day time series obtained between 1996 and 2008 we have computed a total of 221 sets of m-averaged power spectra for spherical harmonic degrees ranging up to 1000. We have then fit these 284 sets of m-averaged power spectra using our WMLTP fitting code and both symmetric Lorentzian profiles for the peaks as well as the asymmetric profile of Nigam and Kosovichev to obtain 568 tables of p-mode parameters. We then inter-compared these 568 tables, and we performed linear regression analyses of the differences in p-mode frequencies, widths, amplitudes, and asymmetries as functions of the differences in as many as ten different solar activity indices. From the linear regression analyses that we performed on the frequency difference data sets, we have discovered a new signature of the frequency shifts of the p-modes. Specifically, we have discovered that the temporal shifts of the solar oscillation frequencies are positively correlated with the changes in solar activity below a limiting frequency. They then become anti-correlated with the changes in activity for a range of frequencies before once again becoming positively-correlated with the activity changes at very high frequencies. We have also discovered that the two frequencies where the sensitivities of the temporal frequency shifts change sign also change in phase with the average level of solar activity.

  5. On the prospect of using butterfly diagrams to predict cycle minimum

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1987-01-01

    Features enabling the prediction of the beginning and the length of a solar cycle, in addition to the turning points in the period-growth dichotomy, have been identified based on butterfly diagrams for the period from 1874 to the present. The present results indicate that cycle 21 will be a long-period cycle ending after July 1987. On the assumption that April 1985 was the first occurrence of high latitude new cycle (cycle 22) spots during the decline of cycle 21 (the old cycle), it is suggested that the last occurrence of high latitude old cycle spots was September 1983 and that the minimum for cycle 22 will be about 1986.7 + or - 1.1 yr.

  6. Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

    NASA Astrophysics Data System (ADS)

    Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth, Gabor; Lee, Yuni; Nagy, Andrew F.; Tenishev, Valeriy; Pawlowski, Dave J.; Combi, Michael R.; Najib, Dalal

    2015-09-01

    A comprehensive study of the solar wind interaction with the Martian upper atmosphere is presented. Three global models: the 3-D Mars multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme MHD code (MF-MHD), the 3-D Mars Global Ionosphere Thermosphere Model (M-GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS) were used in this study. These models are one-way coupled; i.e., the MF-MHD model uses the 3-D neutral inputs from M-GITM and the 3-D hot oxygen corona distribution from M-AMPS. By adopting this one-way coupling approach, the Martian upper atmosphere ion escape rates are investigated in detail with the combined variations of crustal field orientation, solar cycle, and Martian seasonal conditions. The calculated ion escape rates are compared with Mars Express observational data and show reasonable agreement. The variations in solar cycles and seasons can affect the ion loss by a factor of ˜3.3 and ˜1.3, respectively. The crustal magnetic field has a shielding effect to protect Mars from solar wind interaction, and this effect is the strongest for perihelion conditions, with the crustal field facing the Sun. Furthermore, the fraction of cold escaping heavy ionospheric molecular ions [(O2+ and/or O2+)/Total] are inversely proportional to the fraction of the escaping (ionospheric and corona) atomic ion [O+/Total], whereas O2+ and O2+ ion escape fractions show a positive linear correlation since both ion species are ionospheric ions that follow the same escaping path.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Yeates, A. R.; Baker, D.; van Driel-Gesztelyi, L.

    2015-11-01

    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 it is located at high latitude. This is in accordance with previous flux-transport models.

  9. A Combined Analysis of the Observational Aspects of the Quasi-biennial Oscillation in Solar Magnetic Activity

    NASA Astrophysics Data System (ADS)

    Bazilevskaya, G.; Broomhall, A.-M.; Elsworth, Y.; Nakariakov, V. M.

    2014-12-01

    Solar quasi-biennial oscillations (QBOs) with the time scale of 0.6-4 yrs appear to be a basic feature of the Sun's activity. Observational aspects of QBOs are reviewed on the basis of recent publications. Solar QBOs are shown to be ubiquitous and very variable. We demonstrate that many features of QBOs are common to different observations. These features include variable periodicity and intermittence with signs of stochastisity, a presence at all levels of the solar atmosphere and even in the convective zone, independent development in the northern and southern solar hemispheres, most pronounced amplitudes during the maximum phase of the 11-yr cycle and the transition of QBOs into interplanetary space. Temporal weakening of solar activity around the maximum of the 11-yr cycle (Gnevyshev Gap) can be considered an integral part of QBOs. The exact mechanism by which the solar QBO is produced is poorly understood. We describe some of the most plausible theoretical mechanisms and discuss observational features that support/contradict the theory. QBOs have an important meaning as a benchmark of solar activity, not only for investigation of the solar dynamo but also in terms of space weather.

  10. The high energetic particles released during the decline phases of last five solar cycles

    NASA Astrophysics Data System (ADS)

    Hady, A. A., II

    2014-12-01

    During the decline phases of the last five solar cycles, new peak has appeared releasing high energetic particles. During October 2003 (so-called Halloween storms), a sudden increase of the solar activity occurred during the decline phase which has bigger than that occurred during the main peak of that Solar cycle 23. The same situation was repeated again for the solar cycle 24, during its decline phase, giving a new peak during January 2014 and release high energetic particles, which was bigger than that occurred during the mean peak of cycle 24. This means that the solar cycles starting from the cycle 20 have two peaks, the second peak always producing higher energetic flares which affects the Earth's magnetic field. The same situation happened in the cycles 21, and 22, but with lower release of energetic particle, compared with cycles 23 and 24. We will do descriptive studies of these events, according to data analysis, and compare the results. Keywords: Solar cycles; solar activities; solar energetic particles, Halloween storms, January 2014 storms.

  11. Solar Cycle Dependence of Umbral Magneto-Induced Line Broadening

    NASA Astrophysics Data System (ADS)

    Schad, T. A.; Penn, M. J.

    2008-05-01

    Studies of the solar cycle dependence of peak umbral magnetic field strength have focused upon measurements of continuum intensity and the Zeeman splitting of infrared spectral lines. Here we extend the discussion into a measurement of effective line width using eleven years of spectromagnetograms from the Kitt Peak Vacuum Telescope (KPVT). The KPVT observed the 868.8 nm Fe I absorption line in opposing states of circular polarization between 1992 and 2003, deriving full-disk images of line-of-sight (LOS) velocity, LOS magnetic flux, continuum intensity, equivalent line width, and central line depth. We determine an effective spectral line width through a relation of the measured equivalent line widths and central line depths. Developing a basic model of the Stokes line profiles using the Seares formalism, we illustrate that a change in the effective line width within the umbra as determined using the KPVT data is consistent with the change in the Zeeman splitting. We discuss the effect of observed distance from disk center, stray light, and the unknown inclination angle of the magnetic field. Within individual sunspots observed near disk center, the determined effective line width decreases with distance from the umbral core consistent with the studied magnetic field gradient. Measurements of different sunspots show a clear dependence on umbral size consistent with previous studies of the umbral magnetic field. Using this effective line width as a diagnostic for magnetic field, we examine the dependence of maximum magnetic field strength on the phase of the solar cycle. We present a comprehensive statistical analysis using a sample size of over 3500 umbral measurements.

  12. Properties of Magnetic Tongues over a Solar Cycle

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  13. Modelling Variations in Total Solar Irradiance during Cycle 22

    NASA Astrophysics Data System (ADS)

    Chapman, G. A.; Cookson, A. M.; Dobias, J. J.

    1995-12-01

    We have compared total solar irradiance from Nimbus-7 and ACRIM1 with ground- based photometry from the San Fernando Observatory (SFO). The ground-based photometry consisted of photometric sunspot deficits and a photometric facular index. In some instances, we have included UV data from NOAA-9. For Nimbus-7 data, from 30 May 1988 to 13 December 1993, using all three sets of data, we find for 745 days of data a coefficient of multiple correlation, R\\^2, of 0.89. The value of the quiet sun irradiance was 1371.67 +/- 0.21 W/m\\^2. For a subset of these Nimbus-7 data, the rms noise was 0.19 W/m\\^2. For ACRIM1 data, for the period from March 1985 to July 1989 the value of R\\^2 was 0.81 for 685 days of data. For this interval, only the photometric sunspot deficit and NOAA9 UV data were used. The quiet sun irradiance was 1366.96 +/- 0.21 W/m\\^2. The Nimbus-7 analysis, from 30 May 1988 to 13 December 1993, covers the rise, peak, and decline for solar cycle 22. The residuals show no evidence of the rise and decline in irradiance that can be seen in the Nimbus-7 data. We conclude that, to an uncertainty of about 200 parts per million of the mean irradiance, sunspots, faculae, and the network appear to explain all of the long term variation in the total solar irradiance. This research has been partially supported by grants from NSF (ATM-9115111) and NASA (NAGW-3017). Most of the SFO observations have been obtained by students to numerous to list.

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

    NASA Astrophysics Data System (ADS)

    Ettinger, Sophie

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Richardson, Ian G.; Cane, Hilary V.

    2012-01-01

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

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

    SciTech Connect

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

    2014-11-01

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

  19. Electron–Ion Intensity Dropouts in Gradual Solar Energetic Particle Events during Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Tan, Lun C.

    2017-09-01

    Since the field-line mixing model of Giacalone et al. suggests that ion dropouts cannot happen in the “gradual” solar energetic particle (SEP) event because of the large size of the particle source region in the event, the observational evidence of ion dropouts in the gradual SEP event should challenge the model. We have searched for the presence of ion dropouts in the gradual SEP event during solar cycle 23. From 10 SEP events the synchronized occurrence of ion and electron dropouts is identified in 12 periods. Our main observational facts, including the mean width of electron–ion dropout periods being consistent with the solar wind correlation scale, during the dropout period the dominance of the slab turbulence component and the enhanced turbulence power parallel to the mean magnetic field, and the ion gyroradius dependence of the edge steepness in dropout periods, are all in support of the solar wind turbulence origin of dropout events. Also, our observation indicates that a wide longitude distribution of SEP events could be due to the increase of slab turbulence fraction with the increased longitude distance from the flare-associated active region.

  20. The McIntosh Archive: A solar feature database spanning four solar cycles

    NASA Astrophysics Data System (ADS)

    Gibson, S. E.; Malanushenko, A. V.; Hewins, I.; McFadden, R.; Emery, B.; Webb, D. F.; Denig, W. F.

    2016-12-01

    The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly H-alpha, He-1 10830 and photospheric magnetic measurements from both ground-based and NASA satellite observations. With these he traced coronal holes, polarity inversion lines, filaments, sunspots and plage, yielding a unique 45-year record of the features associated with the large-scale solar magnetic field. We will present the results of recent efforts to preserve and digitize this archive. Most of the original hand-drawn maps have been scanned, a method for processing these scans into digital, searchable format has been developed and streamlined, and an archival repository at NOAA's National Centers for Environmental Information (NCEI) has been created. We will demonstrate how Solar Cycle 23 data may now be accessed and how it may be utilized for scientific applications. In addition, we will discuss how this database of human-recognized features, which overlaps with the onset of high-resolution, continuous modern solar data, may act as a training set for computer feature recognition algorithms.

  1. Association of Supergranule Mean Scales with Solar Cycle Strengths and Total Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Mandal, Sudip; Chatterjee, Subhamoy; Banerjee, Dipankar

    2017-07-01

    We analyze the long-term behavior of the supergranule scale parameter, in active regions (ARs) and quiet regions (QRs), using the Kodaikanal digitized data archive. This database provides century-long daily full disk observations of the Sun in Ca ii K wavelengths. In this paper, we study the distributions of the supergranular scales, over the whole data duration, which show identical shape in these two regimes. We found that the AR mean scale values are always higher than that of the QR for every solar cycle. The mean scale values are highly correlated with the sunspot number cycle amplitude and also with total solar irradiance (TSI) variations. Such a correlation establishes the cycle-wise mean scale as a potential calibrator for the historical data reconstructions. We also see an upward trend in the mean scales, as has already been reported in TSI. This may provide new input for climate forcing models. These results also give us insight into the different evolutionary scenarios of the supergranules in the presence of strong (AR) and weak (QR) magnetic fields.

  2. Solar Source and CME Properties of Solar Cycle 23 Ground Level Enhancement Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Xie, H.; Yashiro, S.; Akiyama, S.; Makela, P.; Usoskin, I.

    2010-01-01

    Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. GLE events are extreme cases of solar energetic particle (SEP) events in that the energetic particles penetrate Earth's neutral atmosphere to be detected by neutron monitors. In this paper we present the CME and their source properties that seem to be equally extreme. These observations are consistent with the idea that the GLE particles are accelerated in the same way as the regular SEP events by CME-driven shocks. While we cannot rule out the possibility of the presence of a flare component during GLE events, we can definitely say that a shock component is present in all the GLE events. We provide additional information on the GLE-associated type II radio bursts, complex type III radio bursts, and soft X-ray flares, which are not very different from those associated with large SEP events. Finally we compare the properties of GLEassociated CMEs in cycle 23 with those in cycle 22.

  3. Coronal electron temperature in the protracted solar minimum, the cycle 24 mini maximum, and over centuries

    NASA Astrophysics Data System (ADS)

    Schwadron, N. A.; Goelzer, M. L.; Smith, C. W.; Kasper, J. C.; Korreck, K.; Leamon, R. J.; Lepri, S. T.; Maruca, B. A.; McComas, D.; Steven, M. L.

    2014-03-01

    Recent in situ observations of the solar wind show that charge states (e.g., the O7+/O6+and C6+/C5+abundance ratios) evolved through the extended, deep solar minimum between solar cycles 23 and 24 (i.e., from 2006 to 2009) reflecting cooler electron temperatures in the corona. We extend previous analyses to study the evolution of the coronal electron temperature through the protracted solar minimum and observe not only the reduction in coronal temperature in the cycles 23-24 solar minimum but also a small increase in coronal temperature associated with increasing activity during the "mini maximum" in cycle 24. We use a new model of the interplanetary magnetic flux since 1749 to estimate coronal electron temperatures over more than two centuries. The reduction in coronal electron temperature in the cycles 23-24 protracted solar minimum is similar to reductions observed at the beginning of the Dalton Minimum (˜1805-1840). If these trends continue to reflect the evolution of the Dalton Minimum, we will observe further reductions in coronal temperature in the cycles 24-25 solar minimum. Preliminary indications in 2013 do suggest a further post cycle 23 decline in solar activity. Thus, we extend our understanding of coronal electron temperature using the solar wind scaling law and compare recent reductions in coronal electron temperature in the protracted solar minimum to conditions that prevailed in the Dalton Minimum.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    SciTech Connect

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Damé, Luc

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

  7. The Influence of Solar Proton Events in Solar Cycle 23 on the Neutral Middle Atmosphere

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; vonKonig, Miriam; Anderson, John; Roble, Raymond G.; McPeters, Richard D.; Fleming, Eric L.; Russell, James M.

    2004-01-01

    Solar proton events (SPEs) can cause changes in constituents in the Earth's middle atmosphere. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HO(x) (H, OH, HO2) and NO(y) (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HO(x) increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HO, constituents. The NO(x) increases lead to long-lived stratospheric ozone changes because of the long lifetime of NO(y) constituents in this region. Solar cycle 23 was quite active with SPEs and very large fluxes of high energy protons occurred in July and November 2000, November 200 1, and April 2002. Smaller, but still substantial, proton fluxes impacted the Earth during other months in the 1997-2003 time period. The impact of the very large SPEs on the neutral middle atmosphere during solar cycle 23 will be discussed, including the HO(x), NO(y), ozone variations and induced atmospheric transport changes. Two multi-dimensional models, the Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model and the Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM), were used in computing the influence of the SPEs. The results of the GSFC 2D Model and the TIME-GCM will be shown along with comparisons to the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv

    2016-07-01

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

  11. Solar Spectral Irradiance Variability in Cycle 24: Model Predictions and OMI Observations

    NASA Technical Reports Server (NTRS)

    Marchenko, S.; DeLand, M.; Lean, J.

    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 nanometers during the ongoing Cycle 24. We supplement the OMI data with concurrent observations from the GOME-2 (Global Ozone Monitoring Experiment - 2) and SORCE (Solar Radiation and Climate Experiment) instruments and find fair-to-excellent agreement between the observations and predictions of the NRLSSI2 (Naval Research Laboratory Solar Spectral Irradiance - post SORCE) and SATIRE-S (the Naval Research Laboratory's Spectral And Total Irradiance REconstruction for the Satellite era) models.

  12. Sunspot variation and selected associated phenomena: A look at solar cycle 21 and beyond

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1982-01-01

    Solar sunspot cycles 8 through 21 are reviewed. Mean time intervals are calculated for maximum to maximum, minimum to minimum, minimum to maximum, and maximum to minimum phases for cycles 8 through 20 and 8 through 21. Simple cosine functions with a period of 132 years are compared to, and found to be representative of, the variation of smoothed sunspot numbers at solar maximum and minimum. A comparison of cycles 20 and 21 is given, leading to a projection for activity levels during the Spacelab 2 era (tentatively, November 1984). A prediction is made for cycle 22. Major flares are observed to peak several months subsequent to the solar maximum during cycle 21 and to be at minimum level several months after the solar minimum. Additional remarks are given for flares, gradual rise and fall radio events and 2800 MHz radio emission. Certain solar activity parameters, especially as they relate to the near term Spacelab 2 time frame are estimated.

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

    NASA Astrophysics Data System (ADS)

    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 qA<0). The solar flux component of toward field vector was larger in magnitude than those of away field vector during the negative polarity epochs (1986-88 and 2001-08). In addition, the solar wind speeds (SWS) are faster by about 22.11±4.5 km/s for away polarity days than for toward polarity days during the qA<0 epoch (2001-08), where the IMF 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.

  14. Solar cycle dependence of the distribution of solar wind in-situ plasma parameters, and how this drives solar wind-magnetosphere coupling parameters.

    NASA Astrophysics Data System (ADS)

    Tindale, Elizabeth; Chapman, Sandra

    2017-04-01

    Climate is the statistical distribution of observed weather and we thus expect the climate of space weather to vary with the solar cycle of activity. The 11-year solar cycle is irregular, with each cycle exhibiting a unique duration and peak activity. The distinct activity of each cycle is then coupled from the Sun to the Earth's magnetosphere via the solar wind, leading to long-term trends in the statistics of space weather. Here, we introduce the data quantile-quantile (DQQ) plot as a model-independent method for tracing solar cycle changes in the likelihood of observing a given energy flow in the solar wind. We apply the method to 1-minute resolution Wind data spanning the minima and maxima of cycles 23 and 24 [1]. We consider in-situ solar wind plasma parameters in fast and slow solar wind such as the magnetic energy density and the Poynting flux and how these influence commonly used solar wind-magnetosphere coupling functions such as Akasofu's ɛ parameter. The core of the plasma parameter distributions retains a log-normal functional form simply varying in amplitude with the solar cycles, in agreement with previous work [e.g. 2] and suggestive of a multiplicative underlying physical process consistent with turbulence. The DQQ method also identifies the threshold energy flux at which solar wind plasma parameters depart from the lognormal regime; this 'extremal' component exhibits its own dependence on the solar cycle which is distinct between fast and slow wind. How the solar wind plasma parameter distributions vary, and how this variation is reflected in that of the solar wind-magnetosphere coupling functions, is different between fast and slow solar wind. We can use this approach to compare different solar wind-magnetosphere coupling parameters to determine which, and under what conditions, are most sensitive to these solar cycle solar wind changes. [1] Tindale, E., and S.C. Chapman (2016), Geophys. Res. Lett., 43(11), doi: 10.1002/2016GL068920. [2] Burlaga

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

    SciTech Connect

    Ryan, Daniel F.; Gallagher, Peter T.; Milligan, Ryan O.; Dennis, Brian R.; Kim Tolbert, A.; Schwartz, Richard A.; Alex Young, C.

    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/.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  17. Solar Cycle Dependence of the Solar Wind Dynamics: Pioneer, Voyager, and Ulysses from 1 to 5 AU

    NASA Technical Reports Server (NTRS)

    Gonzalez-Esparza, J. A.; Smith, E. J.

    1996-01-01

    Significant differences between Pioneer and Voyager observations were found in solar wind structure between 1 to 6 AU. These disagreements were attributed to temporal effects related to the solar cycle, but no unifying study of Pioneer-Voyager observations was performed.

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

    NASA Astrophysics Data System (ADS)

    Svoreň, J.

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Pogrebnoy, V.; Malosiev, T.

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

  20. Shannon Entropy-Based Prediction of Solar Cycle 25

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  3. Probing the equinoctial hypothesis over recent solar cycles

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    SciTech Connect

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

    2013-04-20

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

  5. THE 'TWIN-CME' SCENARIO AND LARGE SOLAR ENERGETIC PARTICLE EVENTS IN SOLAR CYCLE 23

    SciTech Connect

    Ding, Liuguan; Jiang, Yong; Zhao, Lulu; Li, Gang

    2013-01-20

    Energetic particles in large solar energetic particle (SEP) events are a major concern for space weather. Recently, Li et al. proposed a 'twin-CME' scenario for ground-level events. Here we extend that study to large SEP events in solar cycle 23. Depending on whether preceding coronal mass ejections (CMEs) within 9 hr exist and whether ions >10 MeV nucleon{sup -1} exceed 10 pfu, we categorize fast CMEs with speed >900 km s{sup -1} and width >60 Degree-Sign from the western hemisphere source regions into four groups: groups I and II are 'twin' and single CMEs that lead to large SEPs; groups III and IV are 'twin' and single CMEs that do not lead to large SEPs. The major findings of this paper are: first, large SEP events tend to be 'twin-CME' events. Of 59 western large SEP events in solar cycle 23, 43 are 'twin-CME' (group I) events and 16 are single-CME (group II) events. Second, not all 'twin CMEs' produced large SEPs: 28 twin CMEs did not produce large SEPs (group III events). Some of them produced excesses of particles up to a few MeV nucleon{sup -1}. Third, there were 39 single fast CMEs that did not produce SEPs (group IV events). Some of these also showed an excess of particles up to a few MeV nucleon{sup -1}. For all four groups of events, we perform statistical analyses on properties such as the angular width, the speed, the existence of accompanying metric type II radio bursts, and the associated flare class for the main CMEs and the preceding CMEs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. On the probability of solar CR fluency during SEP event in dependence of the level of solar activity and position in solar cycle

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Pustil'Nik, L. A.

    For determining of the probability of real radiation hazard for space probes in the interplanetary space on different distances from the Sun, for astronauts and satellites in the Earth's magnetosphere on different orbits, for crew and passengers of regular air-plane lines on different altitudes and at different cut off rigidities, for people and technology on the ground in dependence of geographical position and air pressure is very important to know the probability of dangerous fluency of solar CR not only averaged for many years (it is necessary for the first approximation), but also in dependence on the level of solar activity, as well as in dependence of the investigated time position relative to maximum and minimum of solar activity cycle. These probabilities we determine on the basis of available data on ground and satellite direct measurements of solar CR fluencies for the last several solar cycles as well as available nitrate data in the Greenland's ice on solar CR fluencies for more than 30 solar cycles. The obtained probabilities of solar CR fluencies in dependence of fluency value averaged for solar cycle and for sunspot number intervals 0-40, 40-80, 80-120, 120-160, 160-200 and more than 200 as well as for special time intervals before, during and after solar maximum and minimum, - we try to approximate by analytical formulas. These formulas will be convenient for practical using for estimation of the probability of the solar energetic particle (SEP) event and expected radiation hazard expected for different objects in space, in magnetosphere, and on the ground in dependence of the object's position, level of solar activity and time relative to the maximum and minimum of solar activity cycle. This research is in the frame of program INTAS 0810 and new Project COST 724.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  10. Magnetic Cloud Bz solar cycle variation and the space weather implications

    NASA Astrophysics Data System (ADS)

    Li, Y.; Luhmann, J. G.; Jian, L.; Russell, C. T.

    2016-12-01

    The relationship between magnetic cloud (MC) polarity and the solar magnetic field polarity cycle is extended up to the present. In spite of the weak solar polar fields, the related complications of helmet streamer belt and source surface neutral line over the recent solar cycle, the MC polarity solar cycle variation pattern continues to be true. A trend related to the long solar minimum between cycles 23 and 24are longer periods of N-S polarity MCs. The MC polarity patterns at the STEREO sites generally reflect that at L1. Combining the MC events at three observing points (L1 and STEREO A&B) provides a larger data sample, and the normalized result reenforce and clarify the MC polarity trend. We conclude with some discussions regarding source regions and space weather implications.

  11. QBO as Potential Amplifier of Solar Cycle Influence

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    PubMed

    Currie, R G

    1981-01-23

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

  13. A new solar cycle model including meridional circulation

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  14. Energy transfer in the solar system

    NASA Astrophysics Data System (ADS)

    Jelbring, H.

    2013-12-01

    Different types of energy transfer are presented from the literature and are approached and commented on. It follows from these articles that energy transfer in addition to solar irradiation is less well understood by contemporary scientist. The transformation of energy between kinetic and potential energy in planetary orbits might be of crucial importance for understanding energy transfer between celestial bodies and the development of commensurabilities. There is evidence pointing to interactions (friction) between space and satellites producing volcanism. The reversible transfer of energy between the orbit of Moon and Earth's rotational energy is crucial to the creation of the 13.6-day and 27.3-day periods in both solar variables and Earth bound climate variables. It is hypothesized that the Earth-Moon system is modulating the sunspot numbers and creating both these periods, and that the great planets are responsible for the 11 yr solar cycle.

  15. SOLAR CYCLE 24: CURIOUS CHANGES IN THE RELATIVE NUMBERS OF SUNSPOT GROUP TYPES

    SciTech Connect

    Kilcik, A.; Yurchyshyn, V. B.; Ozguc, A.; Rozelot, J. P.

    2014-10-10

    Here, we analyze different sunspot group (SG) behaviors from the points of view of both the sunspot counts (SSCs) and the number of SGs, in four categories, for the time period of 1982 January-2014 May. These categories include data from simple (A and B), medium (C), large (D, E, and F), and decaying (H) SGs. We investigate temporal variations of all data sets used in this study and find the following results. (1) There is a very significant decrease in the large groups' SSCs and the number of SGs in solar cycle 24 (cycle 24) compared to cycles 21-23. (2) There is no strong variation in the decaying groups' data sets for the entire investigated time interval. (3) Medium group data show a gradual decrease for the last three cycles. (4) A significant decrease occurred in the small groups during solar cycle 23, while no strong changes show in the current cycle (cycle 24) compared to the previous ones. We confirm that the temporal behavior of all categories is quite different from cycle to cycle and it is especially flagrant in solar cycle 24. Thus, we argue that the reduced absolute number of the large SGs is largely, if not solely, responsible for the weak cycle 24. These results might be important for long-term space weather predictions to understand the rate of formation of different groups of sunspots during a solar cycle and the possible consequences for the long-term geomagnetic activity.

  16. Radio scintillation variations of the circumsolar plasma over the course of the solar cycle

    NASA Technical Reports Server (NTRS)

    Lotova, N. A.; Korelov, O. A.; Bird, M. K.; Paetzold, M.; Sieber, W.; Guesten, R.

    1995-01-01

    Interplanetary scintillation observations of the solar wind acceleration region (solar elongation: R approximately 4-30 R(solar mass)) have been performed at the Effelsberg and Pushino telescopes using natural radio sources. The water maser source IRC-20431 was observed at the wavelength lambda = 1.35 cm in a series of nine scintillation experiments performed during the December solar occultations from 1981 to 1994. Dramatic changes in the radial dependence of the scintillation index m(R) were recorded over the course of the 11-year solar cycle. Decidedly reduced scattering, attributed to a pronounced heliolatitude effect, was observed at the closest solar approach distances in the years around solar activity minimum. The anisotropy of the solar scattering region slowly evolves to a spherically symmetric pattern in the years of high solar activity as more intensive scattering returns to the polar latitudes.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Scherer, K.; Fahr, H. J.

    2003-06-01

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

  1. Flexible thermal cycle test equipment for concentrator solar cells

    DOEpatents

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

    2012-06-19

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

  2. The response of chemistry and climate to the 11-year solar cycle in UM-UKCA

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    It is now generally agreed that the UV variability associated with the 11-year solar cycle leads to changes in ozone and temperature in the upper stratosphere. In addition, a range of observational and modelling studies suggest that such changes are the starting point for a chain of processes (including feedbacks) resulting in circulation changes in many areas of the atmosphere. However, precise details of the interactions between chemistry and meteorology induced by solar variability remain under question. In our study, we use a version of the UM-UKCA chemistry-climate model with consistent spectrally-resolved solar variability. While the solar cycle in heating rates has been applied with the method used in HadGEM2-ES, fine spectrally-resolved solar variability has been uniquely incorporated into the Fast-JX photolysis scheme. We perform two 50-year-long perpetual year solar maximum and solar minimum integrations and complement them with a three member ensemble of a transient 1960-2010 integration in which boundary conditions correspond by and large to the CCMI Ref-C1 scenario. We show how the inferred solar signals vary between the individual experiments. This indicates high natural variability and the resulting contamination of the solar signal with contributions from other processes as well as the existence of possible non-linearities between the solar cycle and other atmospheric forcings. Therefore, we highlight that long data series are needed to ensure correct attribution of the modelled and observed anomalies. In addition, we present results from two perpetual year experiments in which the solar cycle was applied exclusively in either short-wave heating or photolysis. We find large non-linearities in the modelled anomalies as compared to the realistic integration with both modulations included. This highlights the subtle nature of the dynamical response to the solar cycle forcing and indicates the need for interactive chemistry with a detailed photolysis

  3. Solar cycle review /General aspects/. [phenomena at photosphere-chromosphere and coronal levels and in interplanetary space

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1976-01-01

    Several topics are discussed in this review of the solar cycle. The basic solar-interplanetary magnetic structure is considered, and the high speed solar wind streams and their sunspot cycle variation are described, with attention to the sunspot cycle variation, the high speed solar wind streams and geomagnetic disturbances, and the causes of changes of the north-south component of the interplanetary magnetic field. Solar storms, solar flares, and magnetic bubbles are examined with attention directed to the solar cycle variation of transient polar activities and the interplanetary disturbances associated with solar storms. Some features of cosmic rays, the 11-year cycle variation and the Forbush decreases, are considered. Attention is also directed to the terrestrial atmosphere and to the outer planets and their relation to the solar cycle.

  4. The sunspot cycle no. 24 in relation to long term solar activity variation

    PubMed Central

    Komitov, Boris; Kaftan, Vladimir

    2013-01-01

    The solar minimum between solar cycles 23 and 24 during the period 2007–2009 has been the longest and deepest one at least since for the last 100 years. We suggest that the Sun is going to his next supercenturial minimum. The main aim of this paper is to tell about arguments concerning this statement. They are based on series of studies, which have been provided during the period since 1997 up to 2010. The progress of solar cycle 24 since its minimum at the end of 2008 up to the end of October 2011 in the light of long term solar activity dynamics is analyzed. PMID:25685429

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

    NASA Astrophysics Data System (ADS)

    Vokhmyanin, Mikhail

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

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

    PubMed

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

    2015-06-01

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

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

    SciTech Connect

    Neises, Ty; Turchi, Craig

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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 < s ≾ 3 AU seem to be useful, but those outside this range are probably unreliable, as evidenced by the anticorrelation between apparent path length and release time estimated from the X-ray activity. It also appears that even the first-arriving energetic protons apparently undergo significant pitch angle scattering in the interplanetary medium, with the resulting apparent path length being

  13. Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock–Leighton Solar Dynamo Model

    NASA Astrophysics Data System (ADS)

    Karak, Bidya Binay; Miesch, Mark

    2017-09-01

    We present results from a three-dimensional Babcock–Leighton (BL) dynamo model that is sustained by the emergence and dispersal of bipolar magnetic regions (BMRs). On average, each BMR has a systematic tilt given by Joy’s law. Randomness and nonlinearity in the BMR emergence of our model produce variable magnetic cycles. However, when we allow for a random scatter in the tilt angle to mimic the observed departures from Joy’s law, we find more variability in the magnetic cycles. We find that the observed standard deviation in Joy’s law of {σ }δ =15^\\circ produces a variability comparable to the observed solar cycle variability of ∼32%, as quantified by the sunspot number maxima between 1755 and 2008. We also find that tilt angle scatter can promote grand minima and grand maxima. The time spent in grand minima for {σ }δ =15^\\circ is somewhat less than that inferred for the Sun from cosmogenic isotopes (about 9% compared to 17%). However, when we double the tilt scatter to {σ }δ =30^\\circ , the simulation statistics are comparable to the Sun (∼18% of the time in grand minima and ∼10% in grand maxima). Though the BL mechanism is the only source of poloidal field, we find that our simulations always maintain magnetic cycles even at large fluctuations in the tilt angle. We also demonstrate that tilt quenching is a viable and efficient mechanism for dynamo saturation; a suppression of the tilt by only 1°–2° is sufficient to limit the dynamo growth. Thus, any potential observational signatures of tilt quenching in the Sun may be subtle.

  14. Solar, geomagnetic and seismic activity

    NASA Astrophysics Data System (ADS)

    Mazzarella, A.; Palumbo, A.

    1988-08-01

    An 11-yr modulation of large Italian earthquakes has been successfully identified and found to be positively linked to sunspot activity. The seismic activity appears to be modulated by the 11-yr sunspot cycle through the coherent variation of geomagnetic activity. It is proposed that the two phenomena are linked by the influence of a magnetostriction process on stresses in the crust. An implication of this model is that geomagnetic storms may directly trigger large earthquakes.

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

    NASA Technical Reports Server (NTRS)

    Hady, Ahmed A.

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

    Deniz Goker, Umit

    2016-07-01

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

  20. RHESSI/SAS Observations of the Optical Solar Limb Over a Full Solar Cycle

    NASA Astrophysics Data System (ADS)

    Fivian, Martin; Hudson, Hugh S.

    2014-06-01

    The Solar Aspect System (SAS) of the RHESSI satellite measures the optical solar limb in the red continuum with a cadence typically set at 16 samples/s in each of three linear CCD sensors. RHESSI has observed the Sun continuously since its launch in early 2002, and we have acquired a unique data set ranging over a full 11-year solar cycle and consisting of about 3x10^10 single data points. Analyzing data for an initial period in 2004, these measurements have led to the most accurate oblateness measurement to date, 8.01+-0.14 milli arcsec (Fivian et al., 2008), a value consistent with models predicting an oblateness from surface rotation. An excess oblateness term can be attributed to magnetic elements possibly located in the enhanced network. We have started to also study photometric properties of our data. Previous observations of latitude-dependent brightness variations at the limb had suggested the presence of a polar temperature excess as large as 1.5 K. The RHESSI observations, made with a rotating telescope in space, have great advantages in the rejection of systematic errors in the very precise photometry required for such an observation. Our new measurements of latitude-dependent brightness variations at the limb lead to a quadrupolar term (a pole-to-equator temperature variation) of the order of 0.1 K, an order of magnitude smaller than previously reported. We present the analysis of these unique data, an overview of some results and we report on our progress as we apply our developed analysis method to the whole 12 years of data.

  1. RHESSI/SAS Observations of the Optical Solar Limb Over a Full Solar Cycle

    NASA Astrophysics Data System (ADS)

    Fivian, M. D.; Hudson, H. S.

    2014-12-01

    The Solar Aspect System (SAS) of the RHESSI satellite measures the optical solar limb in the red continuum with a cadence typically set at 16 samples/s in each of three linear CCD sensors. RHESSI has observed the Sun continuously since its launch in early 2002, and we have acquired a unique data set ranging over a full 11-year solar cycle and consisting of about 3x10^10 single data points. Analyzing data for an initial period in 2004, these measurements have led to the most accurate oblateness measurement to date, 8.01+-0.14 milli arcsec (Fivian et al., 2008), a value consistent with models predicting an oblateness from surface rotation. An excess oblateness term can be attributed to magnetic elements possibly located in the enhanced network. We have started to also study photometric properties of our data. Previous observations of latitude-dependent brightness variations at the limb had suggested the presence of a polar temperature excess as large as 1.5 K. The RHESSI observations, made with a rotating telescope in space, have great advantages in the rejection of systematic errors in the very precise photometry required for such an observation. Our new measurements of latitude-dependent brightness variations at the limb lead to a quadrupolar term (a pole-to-equator temperature variation) of the order of 0.1 K, an order of magnitude smaller than previously reported. We present the analysis of these unique data, an overview of some results and we report on our progress as we apply our developed analysis method to the whole 12 years of data.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  4. The State of the Corona During the Weak Solar Cycle 24: the View from LASCO Images

    NASA Astrophysics Data System (ADS)

    Barlyaeva, T.; Lamy, P.; Llebaria, A.; Boclet, B.

    2016-04-01

    The LASCO-C2 coronagraph onboard SOHO continues its white-light imaging of the corona from 1.5 to 6.0 solar radii, thus allowing investigating the consequences of the weak Solar Cycle 24 on the corona and comparing it to the previous cycle (23). Temporal variations of the global radiance of the corona are presented. We pay particular attention to the mid-term variations which are distinctly different between the two cycles and highlight the similarities and differences. Finally, we rely on our ARTEMIS II catalog of coronal mass ejections (CMEs) to compare their global rates during these two cycles.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; van Loon, H.

    1992-02-01

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

  7. Thermal cycle testing of Space Station Freedom solar array blanket coupons

    NASA Technical Reports Server (NTRS)

    Scheiman, David A.; Schieman, David A.

    1991-01-01

    Lewis Research Center is presently conducting thermal cycle testing of solar array blanket coupons that represent the baseline design for Space Station Freedom. Four coupons were fabricated as part of the Photovoltaic Array Environment Protection (PAEP) Program, NAS 3-25079, at Lockheed Missile and Space Company. The objective of the testing is to demonstrate the durability or operational lifetime of the solar array welded interconnect design within the durability or operational lifetime of the solar array welded interconnect design within a low earth orbit (LEO) thermal cycling environment. Secondary objectives include the observation and identification of potential failure modes and effects that may occur within the solar array blanket coupons as a result of thermal cycling. The objectives, test articles, test chamber, performance evaluation, test requirements, and test results are presented for the successful completion of 60,000 thermal cycles.

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

    NASA Technical Reports Server (NTRS)

    Richon, K.; Schatten, K.

    2003-01-01

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

  9. TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

    SciTech Connect

    Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Cao, W.; Ozguc, A.; Rozelot, J. P.

    2011-04-10

    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 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) 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 solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.

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

    NASA Astrophysics Data System (ADS)

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

    1995-06-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    1991-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

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

    SciTech Connect

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

    2013-04-10

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

  16. A Solar Cycle Lost in 1793-1800: Early Sunspot Observations Resolve the Old Mystery

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

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

    SciTech Connect

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

    2009-08-01

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

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

    SciTech Connect

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

    1990-08-01

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

  19. Solar cycle variations of oscillation mode parameters from LOWL and MARK-I instruments

    NASA Astrophysics Data System (ADS)

    Jimeńez Reyes, S. J.; Corbard, T.; Tomczyk, S.; Pallé, P. L.

    2000-10-01

    The signature of the Solar-Cycle appears clearly in the p-mode parameters (Jiménez-Reyes et al. 1998, Libbrecht & Woodard 1990, and Anguera et al. 1992). At present, the study of the p-mode parameter variation is a very active topic in helioseismology where, thanks to projects like BISON, IRIS, GONG, LOWL and MDI, we are able for the first time to analyse, using heliosismology, how the Sun internal structure and dynamic change over the magnetic cycle. High-quality observations for low degree p-modes have been accumulated for more than twenty years using the solar spectro photometer MARK-I, located and operating at the Observatorio del Teide (Tenerife, Spain). The data-base available have been re-analyzed over a much wider time interval than before. Moreover, the LOWL instrument, a Potassium Magneto-Optical Filter, located at the Manua Loa Observatory, has been measuring for more than six years solar oscillations of intermadiate p-mode degree. The data-base represents one of the best available to analyze the influence of the Solar-Cycle on the mode parameters, mainly because these data, concerning both low and intermadiate degree modes, give us information over an extensive range of the solar depths which may allow us to locate characteristics of the solar dynamo process. Using different data sets and different techniques, we analyse the behaviour of the solar p-modes in an attempt to better understand the origin of the Solar-Cycle.

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

    NASA Technical Reports Server (NTRS)

    Hill, F.

    1984-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Roberts, W. O.

    1974-01-01

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

  2. Proton flares in the variation of the auroral electrojet in solar cycle No. 21.

    NASA Astrophysics Data System (ADS)

    Křivský, L.; Zloch, F.

    1992-09-01

    The effects of the solar proton flare product on ionospheric circumpolar currents (Auroral Electrojet Index) for the interval 1978 - 1986 (solar cycle No. 21) are investigated. A significant increase of the AE two days after the zero-day of appearance of the proton flare was displayed.

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

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

    SciTech Connect

    Landi, E.; Testa, P.

    2014-05-20

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

  6. Properties of Solar Wind Dynamic Pressure Pulses at 1 AU during the Deep Minimum between Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Xie, Y. Q.; Zuo, P. B.; Feng, X. S.; Zhang, Y.

    2015-06-01

    Observations during the deep solar minimum between Solar Cycles 23 and 24 offer an opportunity for characterizing the nature of solar wind dynamic pressure pulses (DPPs) under extreme solar activity. In this study, we identify 226 DPPs from July 2008 to June 2009 using an automatic detection algorithm based on high-resolution plasma data from the Wind spacecraft to investigate the features of DPPs during the deep solar minimum. For comparison, the similarities and differences of the statistical characteristics of the DPPs during the deep solar minimum and during the previous solar minimum are also examined. It is found that the number and the occurrence rate of DPPs during the deep solar minimum are only about one-third of those during the previous minimum, which may be attributed to lower solar wind dynamic pressure and weaker dynamic pressure fluctuations. From a statistical perspective, however, no obvious difference is apparent between the other basic DPP properties in the two solar minima, such as the absolute and relative amplitude of the dynamic pressure changes and the durations of the transition regions of DPPs. Other basic properties of the DPPs during the deep solar minimum are as follows: 1) the distribution of the absolute value of the dynamic pressure amplitude change peaks at 1.0 - 1.5 nPa, 2) the most probable relative pressure changes are 0.2 - 0.8, 3) DPP durations are broad-peaked between 150 s and 210 s with a mean of about 171 s, 4) 76.7 % of the DPPs can be considered as pressure balance structures, 5) dynamic pressure changes across DPPs are dominated by density changes, 6) specially, during the deep solar minimum, a considerable portion of DPPs, 86.7 %, are associated with large-scale solar wind transients such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs).

  7. ON THE VARIATION OF SOLAR RADIUS IN ROTATION CYCLES

    SciTech Connect

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

    2015-01-10

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

  8. The observed relationships between some solar rotation parameters and the activity cycle

    NASA Technical Reports Server (NTRS)

    Howard, R.; Labonte, B. J.

    1983-01-01

    Several parameters of the solar rotation show variations which appear to relate to the phase of the solar-activity cycle. The latitude gradient of the differential rotation, as seen in the coefficients of the sin2 and sin4 terms in the latitude expansion, shows marked variations with the cycle. One of these variations may be described as a one-cycle-per-hemisphere torsional oscillation with a period of 11 years, where the high latitudes rotate faster at solar-activity maximum and slower at minimum, and the low latitudes rotate faster at solar-activity minimum and slower at maximum. Another variation is a periodic oscillation of the fractional difference in the low-latitude rotation between north and south hemispheres. The possibility of a variation in the absolute rotational velocity of the sun in phase with the solar cycle remains an open question. The two-cycle-per-hemisphere torsional waves in the solar rotation also represent an aspect of the rotation which varies with the cycle. It is shown that the amplitude of the fast flowing zone rises a year before the rise to activity maximum. The fast zone seems to be physically the more significant of the two zones.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  12. Solar cycle variations in the neutral exosphere inferred from the location of the Venus bow shock

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Chou, E.; Luhmann, J. G.; Brace, L. H.

    1990-01-01

    Solar UV and EUV varies significantly during the solar cycle. Pioneer Venus can measure this variation both directly and indirectly. A direct measure of the EUV is obtained from the photoelectron current of the Langmuir probe when the spacecraft is in the solar wind. The indirect measure is by monitoring the location of the Venus bow shock. The UV and EUV both heat the upper atmosphere and ionize it. When solar activity is high, the upper atmosphere should be ionized more rapidly. This effect adds a greater number of planetary ions to the magnetosheath plasma as it flows by Venus. It is this increase in mass flow that causes the Venus bow shock to move away from its solar minimum location. Pioneer Venus has now monitored the location of the bow shock for an entire solar cycle. The bow shock location is well correlated with the variation in EUV flux as measured by the Langmuir probe. The bow shock is farther from Venus than expected from the sunspot number or 10.7 cm solar radio flux, indicating that solar UV radiation may be even stronger at the present time than would be predicted from the relationships determined during the previous solar cycle.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    SciTech Connect

    Not Available

    2012-11-01

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

  15. A Study of the Earth-Affecting CMEs of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Hess, Phillip; Zhang, Jie

    2017-06-01

    Using in situ observations from the Advanced Composition Explorer (ACE), we have identified 70 Earth-affecting interplanetary coronal mass ejections (ICMEs) in Solar Cycle 24. Because of the unprecedented extent of heliospheric observations in Cycle 24 that has been achieved thanks to the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instruments onboard the Solar Terrestrial Relations Observatory (STEREO), we observe these events throughout the heliosphere from the Sun to the Earth, and we can relate these in situ signatures to remote sensing data. This allows us to completely track the event back to the source of the eruption in the low corona. We present a summary of the Earth-affecting CMEs in Solar Cycle 24 and a statistical study of the properties of these events including the source region. We examine the characteristics of CMEs that are more likely to be strongly geoeffective and examine the effect of the flare strength on in situ properties. We find that Earth-affecting CMEs in the first half of Cycle 24 are more likely to come from the northern hemisphere, but after April 2012, this reverses, and these events are more likely to originate in the southern hemisphere, following the observed magnetic asymmetry in the two hemispheres. We also find that as in past solar cycles, CMEs from the western hemisphere are more likely to reach Earth. We find that Cycle 24 lacks in events driving extreme geomagnetic storms compared to past solar cycles.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Binay Karak, Bidya

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

  18. Long-Term Solar Cycle Effects on the Ion Escape from Mars

    NASA Astrophysics Data System (ADS)

    Lundin, Rickard; Barabash, Stas; Yamauchi, Masatoshi; Lundstedt, Henrik

    2014-05-01

    The planetary ion escape rate from Mars is solar cycle dependent. During the recent transition from cycle 23 to cycle 24, the escape rate increased by a factor of 10, from 1·1024 s-1 (solar minimum) to 1·1025 s-1 (solar maximum) (Lundin et al., 2013). A regression analysis gives a high correlation between ion escape fluxes and the monthly averaged solar activity proxies F10.7 and Ri (sunspot number). Furthermore, there is a high correlation (0.89) between the monthly F10.7 and Ri, i.e. both proxies are related to the same phenomena, most likely the solar magnetic flux. Similarly, the concentration of radiogenic isotopes in the Earth's atmosphere is controlled by the solar-heliospheric magnetic flux, i.e. the concentration of radiogenic isotopes (e.g. C14 and Be10) can also be used as proxies for the solar magnetic flux. Radiogenic isotopes therefore offers another means to model the long-term ion escape, C14 data going back in time by 12 000 years. From a regression analysis of the relation between C14 and Ri, the empiric model can now be applied to derive Martian ion escape rates much further back in time, compared to that achieved using historic Ri data records (1700 years). Notice that the model does not account for geological and atmospheric effects that may significantly vary on a long-term basis. Furthermore, the model cannot describe short-term effects caused by episodic solar events. Nevertheless, the model may serve as a useful tool to describe long-term effects of solar cycle activity on the Martian atmosphere and ionosphere. References Lundin, R., S.Barabash, M. Holmström, et al., Solar cycle effects on the ion escape from Mars, Geophys. Res Lett., 40, 6028-6032. 2013

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

    NASA Astrophysics Data System (ADS)

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

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

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

    SciTech Connect

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

    2015-09-30

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    The meteor radar measurements obtained at Cachoeira Paulista (22.7°S), Brazil, have been used to study a possible relationship between meteor echo height variations and solar flux during solar cycle 23. A good concordance between the normalized values of the annual mean of the meteor peak heights and F10.7 solar radio flux and Mg_II solar indexes have been observed during declining phase of the solar cycle 23. After eliminating the solar activity influence, the annual mean of the meteor echo peak heights showed a linear decrease of 30 m/year when Mg_II solar index is used and 38 m/year when F10.7 solar radio flux is used. When the trend is eliminated the relationship between meteor peak heights and F10.7 solar flux indicate a trend of 672 m/100 sfu (sfu-solar flux unit). The meteor amplitude signals and the decay time drops after mid-2004, which may be attributed to the decreasing of the electron density in the meteor trails. The meteor echo peak height decrease has been interpreted as being caused by a reduction in air density in the upper atmosphere.

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

    NASA Astrophysics Data System (ADS)

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

    Principle component analysis (PCA) of the solar background magnetic field (SBMF) measured from Wilcox Solar Observatory (WSO) and sunspot magnetic field (SMF) measured by SOHO/MDI magnetograms reveals the two principal components (PCs) of waves travelling in time. In addition, the independent components analysis helps to uncover 8 pairs of SBMF waves in latitudes: two large symmetric magnetic waves , which are the same for all cycles 21-23, and three pairs of asymmetric magnetic waves, which are unique for each cycle. In each pair the waves travel slightly off phase with different phase shift for each cycle and have a different number of equator crossings (Zharkova et al, 2012). These SBMF variations are assumed to be those of poloidal magnetic field traveling slightly off-phase from pole to pole which are caused by a joint action of dipole and quadruple magnetic sources in the Sun. The simulations with the two layer Parker's dynamo model with meridional circulation revealed that the dominant pair of PCs can be produced by a magnetic dip