Parameterized study of the ionospheric modification associated with sun-aligned polar cap arcs

NASA Technical Reports Server (NTRS)

Crain, D. J.; Sojka, J. J.; Schunk, R. W.; Zhu, L.

1993-01-01

The local ionospheric modification that is due to a generalized steady state solar aligned (SA) arc structure is addressed. For a representative set of SA arc parameters which includes both convection and precipitation, emphasis is placed on the modification by SA polar cap arcs upon the F region electron density and the height integrated conductivity. At low fluxes and low characteristic energies, SA polar cap arcs have the most pronounced relative effect at F region altitudes in darkness for winter solar minimum conditions. The absolute enhancement in summer solar minimum and winter solar maximum is equivalent to that of winter solar minimum, but the higher ambient densities make the relative enhancement less. The TEC enhancement associated with an SA arc may be used to indicate the degree of plasma cross flow across the arc.

Leveraging the Polar Cap: Ground-Based Measurements of the Solar Wind

NASA Astrophysics Data System (ADS)

Urban, K. D.; Gerrard, A. J.; Weatherwax, A. T.; Lanzerotti, L. J.; Patterson, J. D.

2016-12-01

In this study, we look at and identify relationships between solar wind quantities that have previously been shown to have direct access into the very high-latitude polar cap as measured by ground-based riometers and magnetometers in Antarctica: ultra-low frequency (ULF) power in the interplanetary magnetic field (IMF) Bz component and solar energetic proton (SEP) flux (Urban [2016] and Patterson et al. [2001], respectively). It is shown that such solar wind and ground-based observations can be used to infer the hydromagnetic structure and magnetospheric mapping of the polar cap region in a data-driven manner, and that high-latitude ground-based instrumentation can be used to infer concurrent various state parameters of the geospace environment.

Directly Driven Ion Outflow

NASA Technical Reports Server (NTRS)

Elliott, H. A.; Comfort, R. H.; Craven, P. D.; Moore, T. E.; Russell, C. T.; Rose, M. Franklin (Technical Monitor)

2001-01-01

We examine ionospheric outflows in the high altitude magnetospheric polar cap during the POLAR satellite's apogee on April 19, 1996 using the Thermal Ion Dynamics Experiment (TIDE) instrument. The elevated levels of O(+) observed in this pass may be due to the geophysical conditions during and prior to the apogee pass. In addition to the high abundance of O(+) relative to H(+), several other aspects of this data are noteworthy. We observe relationships between the density, velocity, and temperature which appear to be associated with perpendicular heating and the mirror force, rather than adiabatic expansion. The H(+) outflow is at a fairly constant flux which is consistent with being source limited by charge exchange at lower altitudes. Local centrifugal acceleration in the polar cap is found to be insufficient to account for the main variations we observe in the outflow velocity. The solar wind speed is high during this pass approximately 700 kilometers per second, and there are Alfve'n waves present in the solar wind such that the solar wind speed and IMF Bx are correlated. In this pass both the H(+) and O(+) outflow velocities correlate with both the solar wind speed and IMF fluctuations. Polar cap magnetometer and Hydra electron data show the same long period wave structure as found in the solar wind and polar cap ion outflow. In addition, the polar cap Poynting flux along the magnetic field direction correlates well with the H(+) temperature (R=0.84). We conclude that the solar wind can drive polar cap ion outflow particularly during polar squalls by setting up a parallel drop that is tens of eV which then causes the ion outflow velocity of O(+) and H(+), the electrons, and magnetic perturbations to vary in a similar fashion.

Babcock Redux: An Amendment of Babcock's Schematic of the Sun's Magnetic Cycle

NASA Astrophysics Data System (ADS)

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

2017-08-01

We amend Babcock's original scenario for the global dynamo process that sustains the Sun's 22-year magnetic cycle. The amended scenario fits post-Babcock observed features of the magnetic activity cycle and convection zone, and is based on ideas of Spruit & Roberts (1983, Nature, 304, 401) about magnetic flux tubes in the convection zone. A sequence of four schematic cartoons lays out the proposed evolution of the global configuration of the magnetic field above, in, and at the bottom of the convection zone through sunspot Cycle 23 and into Cycle 24. Three key elements of the amended scenario are: (1) as the net following-polarity magnetic field from the sunspot-region Ω-loop fields of an ongoing sunspot cycle is swept poleward to cancel and replace the opposite-polarity polar-cap field from the previous sunspot cycle, it remains connected to the ongoing sunspot cycle's toroidal source-field band at the bottom of the convection zone; (2) topological pumping by the convection zone's free convection keeps the horizontal extent of the poleward-migrating following-polarity field pushed to the bottom, forcing it to gradually cancel and replace old horizontal field below it that connects the ongoing-cycle source-field band to the previous-cycle polar-cap field; (3) in each polar hemisphere, by continually shearing the poloidal component of the settling new horizontal field, the latitudinal differential rotation low in the convection zone generates the next-cycle source-field band poleward of the ongoing-cycle band. The amended scenario is a more-plausible version of Babcock's scenario, and its viability can be explored by appropriate kinematic flux-transport solar-dynamo simulations. A paper giving a full description of our dynamo scenario is posted on arXiv (http://arxiv.org/abs/1606.05371).This work was funded by the Heliophysics Division of NASA's Science Mission Directorate through the Living With a Star Targeted Research and Technology Program and the Hinode Project.

Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid

NASA Astrophysics Data System (ADS)

Richardson, M. I.

2002-12-01

Seasonally-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global seasonal water cycle, tied proximately to planetary eccentricity, and the existence of residual ice caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water ice cap. The southern summer residual carbon dioxide ice cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water ice in the northern hemisphere by tropical water ice clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground ice in the mid- and high-latitudes, but this water is likely below the seasonal skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and southern caps. Similar climate-models of the water cycle also do not need much exchangeable adsorbed water in order to explain the observed vapour distributions. The possibility of liquid water is tantalizing, but difficult to definitively judge. On scales greater than a meter or so, Mars is most definitely well away from the water triple point--although the surface pressure can exceed 6.1 mbars, the partial pressure of water vapor (to which the triple point refers) is at best orders of magnitude lower. Several careful studies have shown, however, that locally transient (meta-stable) liquid is possible, if the net heating of ice deposits is high enough. This process is aided if the total surface pressure exceeds 6.1mbar (this prevents boiling, or the explosive loss of vapour into the atmosphere) or if the liquid is covered by a thin ice shell, and is only possible if surface temperatures exceed 273K (for pure water, or the appropriate eutectic for brines) and if ice is present. The former challenge is much easier to meet than the latter. The melt scenario requires that ice deposited in winter must be protected from sublimation as surface temperatures increase in spring, but then exposed to the peak of solar heating in summer. Available spacecraft observations of seasonal water will be discussed with the aid of GCM model simulations, and examined in the context of water distributions and phases.

Comparisons of the North Polar Cap of Mars and the Earth's Northern Hemisphere snow cover

NASA Technical Reports Server (NTRS)

Foster, J.; Owe, M.; Capen, C.

1985-01-01

The boundaries of the polar caps of Mars have been measured on more than 3000 photographs since 1905 from the plate collection at the Lowell Observatory. For the Earth the polar caps have been accurately mapped only since the mid 1960's when satellites were first available to synoptically view the polar regions. The polar caps of both planets wax and wane in response to changes in the seasons, and interannual differences in polar cap behavior on Mars as well as Earth are intimately linked to global energy balance. In this study data on the year to year variations in the extent of the polar caps of Mars and Earth were assembled and analyzed together with data on annual variations in solar activity to determine if associations exist between these data. It was found that virtually no correlation exists between measurements of Mars north polar cap and solar variability. An inverse relationship was found between variations in the size of the north polar caps of Mars and Earth, although only 6 years of concurrent data were available for comparison.

Cleaner for Solar-Collector Covers

NASA Technical Reports Server (NTRS)

Frickland, P. O.; Cleland, E. L.

1983-01-01

Simple self-contained cleaning system proposed for solar collectors or solar-collector protective domes. Perforated transparent plastic cap attached to top of protective dome in heliostat solar-energy collection system distributes cleaning fluid over surface of dome without blocking significant fraction of solar radiation.

Sunlight penetration through the Martian polar caps: Effects on the thermal and frost budgets

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1992-01-01

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

Sunlight penetration through the Martian polar caps - Effects on the thermal and frost budgets

NASA Technical Reports Server (NTRS)

Lindner, Bernhard L.

1992-01-01

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer, and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

THE EFFECT OF ACTIVITY-RELATED MERIDIONAL FLOW MODULATION ON THE STRENGTH OF THE SOLAR POLAR MAGNETIC FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, J.; Cameron, R. H.; Schmitt, D.

We studied the effect of the perturbation of the meridional flow in the activity belts detected by local helioseismology on the development and strength of the surface magnetic field at the polar caps. We carried out simulations of synthetic solar cycles with a flux transport model, which follows the cyclic evolution of the surface field determined by flux emergence and advective transport by near-surface flows. In each hemisphere, an axisymmetric band of latitudinal flows converging toward the central latitude of the activity belt was superposed onto the background poleward meridional flow. The overall effect of the flow perturbation is tomore » reduce the latitudinal separation of the magnetic polarities of a bipolar magnetic region and thus diminish its contribution to the polar field. As a result, the polar field maximum reached around cycle activity minimum is weakened by the presence of the meridional flow perturbation. For a flow perturbation consistent with helioseismic observations, the polar field is reduced by about 18% compared to the case without inflows. If the amplitude of the flow perturbation depends on the cycle strength, its effect on the polar field provides a nonlinearity that could contribute to limiting the amplitude of a Babcock-Leighton type dynamo.« less

Polar Cap Disturbances: Mesosphere and Thermosphere-Ionosphere Response to Solar-Terrestrial Interactions

NASA Technical Reports Server (NTRS)

Sivjee, G.; McEwen, D.; Walterscheid, R.

2003-01-01

The Polar Cap is the Upper-Atmosphere cum Mag-netosphere region which is enclosed by the poleward boundary of the Auroral Oval and is threaded by open geomagnetic tield lines. In this region, there is normally a steady precipition (Polar "drizzle") of low energy (w 300eV) electrons that excite optical emissions from the ionosphere. At times, enhanced ionization patches are formed near the Dayside Cusp regions that drift across the Polar Cap towards the Night Sector of the Auroral Oval. Discrete auroral arcs and auroras formed during Solar Magnetic Cloud (SMC)/Coronal Mass Ejection (CME) events are also observed in the Polar Cap. Spectrophotometric observations of all these Polar Cap phenomena provide a measure of the average energy as well a energy flux of the electrons precipitating in the Polar Cap region during these disturbances. Such measurements also point to modulations of the Polar Cap Mesosphere-Lower Thermosphere (MLT) air density and temperature by zonally symmetric tides whose Hough functions peak in the Polar region. MLT cooling during Stratospheric Warming events and their relation to Polar Vortex and associated Gravity wave activities are also observed at the Polar Cap sites.

Comparison of polar cap potential drops estimated from solar wind and ground magnetometer data - CDAW 6

NASA Technical Reports Server (NTRS)

Reiff, P. H.; Spiro, R. W.; Wolf, R. A.; Kamide, Y.; King, J. H.

1985-01-01

It is pointed out that the maximum electrostatic potential difference across the polar cap, Phi, is a fundamental measure of the coupling between the solar wind and the earth's magnetosphere/ionosphere sytem. During the Coordinated Data Analysis Workshop (CDAW) 6 intervals, no suitably instrumented spacecraft was in an appropriate orbit to determine the polar-cap potential drop directly. However, two recently developed independent techniques make it possible to estimate the polar-cap potential drop for times when direct spacecraft data are not available. The present investigation is concerned with a comparison of cross-polar-cap potential drop estimates calculated for the two CDAW 6 intervals on the basis of these two techniques. In the case of one interval, the agreement between the potential drops and Joule heating rates is relatively good. In the second interval, however, the agreement is not very good. Explanations for this discrepancy are discussed.

Stability of the Martian climate system under the seasonal change condition of solar radiation

NASA Astrophysics Data System (ADS)

Nakamura, Takasumi; Tajika, Eiichi

2002-11-01

Previous studies on stability of the Martian climate system used essentially zero-dimensional energy balance climate models (EBMs) under the condition of annual mean solar radiation income. However, areal extent of polar ice caps should affect the Martian climate through the energy balance and the CO2 budget, and results under the seasonal change condition of solar radiation will be different from those under the annual mean condition. We therefore construct a one-dimensional energy balance climate model with CO2-dependent outgoing radiation, seasonal changes of solar radiation income, changes of areal extent of CO2 ice caps, and adsorption of CO2 by regolith. We have investigated behaviors of the Martian climate system and, in particular, examined the effect of the seasonal changes of solar radiation by comparing the results of previous studies under the condition of annual mean solar radiation. One of the major discrepancies between them is the condition for multiple solutions of the Martian climate system. Although the Martian climate system always has multiple solutions under the annual mean condition, under the seasonal change condition, existence of multiple solutions depends on the present amounts of CO2 in the ice caps and the regolith.

High Latitude Energetic Particle Boundaries: The SAMPEX Database

NASA Astrophysics Data System (ADS)

Kanekal, S. G.; Baker, D. N.

2006-11-01

The size of the polar cap or the open field line region depends, upon the difference in reconnection rates at the dayside between the IMF and the geomagnetic field, and those occurring in the magnetotail. The dayside merging adds flux to the open field region increasing the polar cap size and the magnetic flux in the lobes of the tail, thereby causing energy to be stored in the magnetosphere. Night side reconnection, geomagnetic storms and substorms dissipate this energy removing flux and shrink the polar cap. The dynamics of the polar cap can therefore be useful in the study of the energy dynamics of the magnetosphere. Energetic particles delineate magnetospheric regions, since their motions are governed by the geomagnetic field. Convection and corotation electric fields control the drift of low energy particles whereas magnetic field gradient and curvature are the dominant factors for higher energy (> ~30 keV) particles. High latitude energetic particle boundaries are related to the polar cap and therefore useful in determining the size of the open field line regions We will provide a long database of energetic particle boundaries in the polar regions using instruments aboard SAMPEX, the first of the Small explorer (SMEX) spacecraft. It was launched on July 3, 1992 into a low earth polar orbit. There are four particle detectors, HILT, LICA, PET and MAST on board which point toward the zenith over the poles of the Earth. These detectors measure electrons, protons and ions ranging in energy from tens of keV to a few MeV. This database will comprise the latitudinal (geographic, magnetic and invariant) and longitudinal (geographic and magnetic local time) positions of energetic particle boundaries in the polar regions. The database will cover a time period from launch to about mid 2004. It will therefore cover a significant portion of the solar cycles 22 and 23. Together with interplanetary data obtainable from public databases, such as the NASA OMNI database the SAMPEX energetic particle database can be used to relate Earth's magnetospheric response to the interplanetary drivers such as solar wind speed, density and magnetic field.

La calotta polare sud di Mars

NASA Astrophysics Data System (ADS)

di Giovanni, Giovanni

2006-06-01

The paper discusses the variations in the ice-retreat rate of the south polar cap of Mars in springtime during the 2003 and 2005 apparitions. For this we have measured the planetocentric cap amplitude on images of the Mars Sections of the Italian Union of Amateur Astronomers (UAI), the American Association of Lunar and Planetary Observers (ALPO) and ALPO Japan in the relevant Internet sites. A reasonable first approach to the problem was to perform a simple heat-balance model of Mars' ice cap including solar insolation, surface thermal emission, condensation and sublimation of carbon dioxide frost. The model doesn't include several important physical conditions, such as atmospherical absorption of radiation etc. and other components of ice (i.e. dust, H2O etc.). A suitable mathematical continue function θ(Ls) concerning the planetocentric amplitude of the cap as a function of the areocentric solar longitude on Mars (Ls) has been used to fit the experimental points in a classical diagram cap amplitude versus Ls. The correlation coefficient resulted 0.95. The second derivative of the function (d2θ/dLs2) suggests the existence of three important points during the spring recession: a) at Ls≍228° the highest sublimation rate is observe; b) at Ls≍245° (near perihelion) the highest retraction speed of the edge cap occurs, when the solar radiation flux over the south pole exceeds the flux over the equatorial zone; c) at Ls>285° the retraction speed of the cap's edge is constant. With the same function θ(Ls) we have worked out the ice thickness for every degrees in Ls, sublimation diurnal rate and total mass of seasonal cap. The ring of ice around to the pole, whose existence was suggested by Cross, was not revealed.

Polar Rain Gradients and Field-Aligned Polar Cap Potentials

NASA Technical Reports Server (NTRS)

Fairfield, D. H.; Wing, S.; Newell, P. T.; Ruohoniemi, J. M.; Gosling, J. T.; Skoug, R. M.

2008-01-01

ACE SWEPAM measurements of solar wind field-aligned electrons have been compared with simultaneous measurements of polar rain electrons precipitating over the polar cap and detected by DMSP spacecraft. Such comparisons allow investigation of cross-polar-cap gradients in the intensity of otherwise-steady polar rain. The generally good agreement of the distribution functions, f, from the two data sources confirms that direct entry of solar electrons along open field lines is indeed the cause of polar rain. The agreement between the data sets is typically best on the side of the polar cap with most intense polar rain but the DMSP f's in less intense regions can be brought into agreement with ACE measurements by shifting all energies by a fixed amounts that range from tens to several hundred eV. In most cases these shifts are positive which implies that field-aligned potentials of these amounts exist on polar cap field lines which tend to retard the entry of electrons and produce the observed gradients. These retarding potentials undoubtedly appear in order to prevent the entry of low-energy electrons and maintain charge quasi-neutrality that would otherwise be violated since most tailward flowing magnetosheath ions are unable to follow polar rain electrons down to the polar cap. In more limited regions near the boundary of the polar cap there is sometimes evidence for field-aligned potentials of the opposite sign that accelerate polar rain electrons. A solar electron burst is also studied and it is concluded that electrons from such bursts can enter the magnetotail and precipitate in the same manner as polar rain.

Mars Water Ice and Carbon Dioxide Seasonal Polar Caps: GCM Modeling and Comparison with Mars Express Omega Observations

NASA Technical Reports Server (NTRS)

Forget, F.; Levrard, B.; Montmessin, F.; Schmitt, B.; Doute, S.; Langevin, Y.; Bibring, J. P.

2005-01-01

To better understand the behavior of the Mars CO2 ice seasonal polar caps, and in particular interpret the the Mars Express Omega observations of the recession of the northern seasonal cap, we present some simulations of the Martian Climate/CO2 cycle/ water cycle as modeled by the Laboratoire de Meteorologie Dynamique (LMD) global climate model.

Model and observation comparison of the universal time and IMF by dependence of the ionospheric polar hole

NASA Technical Reports Server (NTRS)

Sojka, J. J.; Schunk, R. W.; Hoegy, W. R.; Grebowsky, J. M.

1991-01-01

The polar ionospheric F-region often exhibits regions of marked density depletion. These depletions have been observed by a variety of polar orbiting ionospheric satellites over a full range of solar cycle, season, magnetic activity, and universal time (UT). An empirical model of these observations has recently been developed to describe the polar depletion dependence on these parameters. Specifically, the dependence has been defined as a function of F10.7 (solar), summer or winter, Kp (magnetic), and UT. Polar cap depletions have also been predicted /1, 2/ and are, hence, present in physical models of the high latitude ionosphere. Using the Utah State University Time Dependent Ionospheric Model (TDIM) the predicted polar depletion characteristics are compared with those described by the above empirical model. In addition, the TDIM is used to predict the IMF By dependence of the polar hole feature.

Climate change

USGS Publications Warehouse

Cronin, Thomas M.

2016-01-01

Climate change (including climate variability) refers to regional or global changes in mean climate state or in patterns of climate variability over decades to millions of years often identified using statistical methods and sometimes referred to as changes in long-term weather conditions (IPCC, 2012). Climate is influenced by changes in continent-ocean configurations due to plate tectonic processes, variations in Earth’s orbit, axial tilt and precession, atmospheric greenhouse gas (GHG) concentrations, solar variability, volcanism, internal variability resulting from interactions between the atmosphere, oceans and ice (glaciers, small ice caps, ice sheets, and sea ice), and anthropogenic activities such as greenhouse gas emissions and land use and their effects on carbon cycling.

Space Plasma Physics

NASA Technical Reports Server (NTRS)

Wu, S. T.

2000-01-01

Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

Fluid core size of Mars from detection of the solar tide

NASA Technical Reports Server (NTRS)

Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

2003-01-01

The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

Fluid Core Size of Mars from Detection of the Solar Tide

NASA Astrophysics Data System (ADS)

Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

2003-04-01

The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

Substorm occurrence rates, substorm recurrence times, and solar wind structure

NASA Astrophysics Data System (ADS)

Borovsky, Joseph E.; Yakymenko, Kateryna

2017-03-01

Two collections of substorms are created: 28,464 substorms identified with jumps in the SuperMAG AL index in the years 1979-2015 and 16,025 substorms identified with electron injections into geosynchronous orbit in the years 1989-2007. Substorm occurrence rates and substorm recurrence-time distributions are examined as functions of the phase of the solar cycle, the season of the year, the Russell-McPherron favorability, the type of solar wind plasma at Earth, the geomagnetic-activity level, and as functions of various solar and solar wind properties. Three populations of substorm occurrences are seen: (1) quasiperiodically occurring substorms with recurrence times (waiting times) of 2-4 h, (2) randomly occurring substorms with recurrence times of about 6-15 h, and (3) long intervals wherein no substorms occur. A working model is suggested wherein (1) the period of periodic substorms is set by the magnetosphere with variations in the actual recurrence times caused by the need for a solar wind driving interval to occur, (2) the mesoscale structure of the solar wind magnetic field triggers the occurrence of the random substorms, and (3) the large-scale structure of the solar wind plasma is responsible for the long intervals wherein no substorms occur. Statistically, the recurrence period of periodically occurring substorms is slightly shorter when the ram pressure of the solar wind is high, when the magnetic field strength of the solar wind is strong, when the Mach number of the solar wind is low, and when the polar-cap potential saturation parameter is high.

Experimental investigation of insolation-driven dust ejection from Mars' CO2 ice caps

NASA Astrophysics Data System (ADS)

Kaufmann, E.; Hagermann, A.

2017-01-01

Mars' polar caps are - depending on hemisphere and season - partially or totally covered with CO2 ice. Icy surfaces such as the polar caps of Mars behave differently from surfaces covered with rock and soil when they are irradiated by solar light. The latter absorb and reflect incoming solar radiation within a thin layer beneath the surface. In contrast, ices are partially transparent in the visible spectral range and opaque in the infrared. Due to this fact, the solar radiation can penetrate to a certain depth and raise the temperature of the ice or dust below the surface. This may play an important role in the energy balance of icy surfaces in the solar system, as already noted in previous investigations. We investigated the temperature profiles inside CO2 ice samples including a dust layer under Martian conditions. We have been able to trigger dust eruptions, but also demonstrated that these require a very narrow range of temperature and ambient pressure. We discuss possible implications for the understanding of phenomena such as arachneiform patterns or fan shaped deposits as observed in Mars' southern polar region.

A study of the relationship between interplanetary parameters and large displacements of the nightside polar cap boundary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lester, M.; Freeman, M.P.; Southwood, D.J.

On July 14, 1982 the Sweden and Britain Radar-Aurora Experiment (SABRE) observed the ionospheric flow reversal boundary at {approximately} 0400 MLT to move equatorward across the radar field of view and then later to return poleward. The polar cap appeared to be considerably inflated at this time. Concurrent observations by ISEE-3 at the L1 libration point of the solar wind speed and density, and of the interplanetary magnetic field (IMF) indicated that the solar wind conditions were unusual throughout the interval under consideration. A mapping of the solar wind parameters from the L1 point to the subsolar magnetopause and thencemore » to the SABRE local time sector indicates that the equatorward motion of the polar cap boundary was controlled by a southward turning of the IMF. The inference of a concomitant increase in open magnetic flux is supported by a comparison of the magnetopause location observed by ISEE-1 on an inbound pass in the 2,100 MLT sector with a magnetopause model based upon the solar wind measurements made by ISEE-3. Some 20 minutes after the expansion of the polar cap boundary was first seen by SABRE, there was a rapid contraction of the boundary, the casue of which was independent of the INF and solar wind parameters, and which had a poleward velocity component in excess of 1,900 m s{sup {minus}1}. the boundary as it moved across the radar field of view was highly structured and oriented at a large angle to the ionospheric footprints of the magnetic L shells. Observations in the premidnight sector by the Air Force Geophysics Laboratory (AFGL) magnetometer array indicate that the polar cap contraction is caused by substorm draining of the polar cap flux and occurs without a clearly associated trigger in the interplanetary medium. The response time in the early morning local time sector to the substorm onset switch is approximately 20 minutes, equivalent to an ionospheric azimuthal phase velocity of some 5 km s{sup {minus}1}.« less

Changes in solar wind-magnetosphere coupling with solar cycle, season, and time relative to stream interfaces

NASA Astrophysics Data System (ADS)

McPherron, Robert L.; Baker, Daniel N.; Pulkkinen, T. I.; Hsu, T.-S.; Kissinger, J.; Chu, X.

2013-07-01

Geomagnetic activity depends on a variety of factors including solar zenith angle, solar UV, strength of the interplanetary magnetic field, speed and density of the solar wind, orientation of the Earth’s dipole, distance of the Earth from Sun, occurrence of CMEs and CIRs, and possibly other parameters. We have investigated some of these using state-dependant linear prediction filters. For a given state a prediction filter transforms a coupling function such as rectified solar wind electric field (VBs) to an output like the auroral electrojet index (AL). The area of this filter calculated from the sum of the filter coefficients measures the strength of the coupling. When the input and output are steady for a time longer than the duration of the filter the ratio of output to input is equal to this area. We find coupling strength defined in this way for Es=VBs to AL (and AU) is weakest at solar maximum and strongest at solar minimum. AL coupling displays a semiannual variation being weakest at the solstices and strongest at the equinoxes. AU coupling has only an annual variation being strongest at summer solstice. AL and AU coupling also vary with time relative to a stream interface. Es coupling is weaker after the interface, but ULF coupling is stronger. Total prediction efficiency remains about constant at the interface. The change in coupling strength with the solar cycle can be explained as an effect of more frequent saturation of the polar cap potential causing a smaller ratio of AL to Es. Stronger AL coupling at the equinoxes possibly indicates some process that makes magnetic reconnection less efficient when the dipole axis is tilted along the Earth-Sun line. Strong AU coupling at summer solstice is likely due to high conductivity in northern summer. Coupling changes at a stream interface are correlated with the presence of strong wave activity in ground and satellite measurements and may be an artifact of the method by which solar wind data are propagated.

Michigan | Midmarket Solar Policies in the United States | Solar Research |

Science.gov Websites

program were retained. System size limit: 150 kW Aggregate cap: 0.75% of utility's peak load of the are currently no community solar policies in Michigan. Utilities and third-party developers offer

New York | Midmarket Solar Policies in the United States | Solar Research |

Science.gov Websites

solar within the state. The statewide solar incentives program, NY-Sun, offers loans and grants for non viability. System size limit: Solar: 25 kW for residential; 100 kW for farms; 2 MW for non-residential. PSEG Long Island: 25 kW for residential solar, 2 MW for non-residential solar Aggregate cap: None PSEG Long

The magnetospheric electric field and convective processes as diagnostics of the IMF and solar wind

NASA Technical Reports Server (NTRS)

Kaye, S. M.

1979-01-01

Indirect measurements of the convection field as well as direct of the ionospheric electric field provide a means to at least monitor quanitatively solar wind processes. For instance, asymmetries in the ionospheric electric field and ionospheric Hall currents over the polar cap reflect the solar wind sector polarity. A stronger electric field, and thus convective flow, is found on the side of the polar cap where the y component of the IMF is parallel to the y component of the geomagnetic field. Additionally, the magnitude of the electric field and convective southward B sub Z and/or solar wind velocity, and thus may indicate the arrival at Earth of an interaction region in the solar wind. It is apparent that processes associated with the convention electric field may be used to predict large scale features in the solar wind; however, with present empirical knowledge it is not possible to make quantitative predictions of individual solar wind or IMF parameters.

Greenland Network (GNET) observations of Polar cap Patches and Arcs

NASA Astrophysics Data System (ADS)

Cesar, V. E.; Pradipta, R.; Pedersen, T.

2017-12-01

TEC values collected with the Greenland Network (GNET) of GPS/GNSS receivers and 630.0 nm airglow emissions recorded with an all-sky imager located at Qaanaaq in Greenland are used to investigate the relationship between the appearance and evolution of polar cap patches (PCP) and Sun-aligned arcs (S-AA) and the characteristics of the solar wind. Both PCP and S-AA produce TEC enhancements, but the PCP velocity is 10 times larger than the S-AA's drift. In addition, PCP move anti-sunwardly and the S-AA move in the dawn-dusk direction. We use these properties of PCPs and S-AAs and calculate the velocity of the TEC enhancements to identify and discriminate between patches and arcs. The physical location of the boundary of the polar cap is based on DMSP observations of particle precipitation. The IMF and other solar wind parameters are gathered with the ACE satellite that is positioned at the L1 point. Our observations indicate that during December 2009, TEC enhancements occur in the polar cap almost every day, but only when the solar wind velocity exceeds 290 km/s. PCPs appear almost immediately after the Bz turns southward; however, the S-AAs develop a few hours after Bz points northward. These conclusions demonstrate the ability of GNET continuous measurements over Greenland to conduct investigations of the formation and evolution of polar cap patches and arcs.

The effects of seasonal and diurnal variations in the Earth's magnetic dipole orientation on solar wind-magnetosphere-ionosphere coupling

NASA Astrophysics Data System (ADS)

Cnossen, Ingrid; Wiltberger, Michael; Ouellette, Jeremy E.

2012-11-01

The angle μ between the geomagnetic dipole axis and the geocentric solar magnetospheric (GSM) z axis, sometimes called the “dipole tilt,” varies as a function of UT and season. Observations have shown that the cross-polar cap potential tends to maximize near the equinoxes, when on average μ = 0, with smaller values observed near the solstices. This is similar to the well-known semiannual variation in geomagnetic activity. We use numerical model simulations to investigate the role of two possible mechanisms that may be responsible for the influence of μ on the magnetosphere-ionosphere system: variations in the coupling efficiency between the solar wind and the magnetosphere and variations in the ionospheric conductance over the polar caps. Under southward interplanetary magnetic field (IMF) conditions, variations in ionospheric conductance at high magnetic latitudes are responsible for 10-30% of the variations in the cross-polar cap potential associated with μ, but variations in solar wind-magnetosphere coupling are more important and responsible for 70-90%. Variations in viscous processes contribute slightly to this, but variations in the reconnection rate with μ are the dominant cause. The variation in the reconnection rate is primarily the result of a variation in the length of the section of the separator line along which relatively strong reconnection occurs. Changes in solar wind-magnetosphere coupling also affect the field-aligned currents, but these are influenced as well by variations in the conductance associated with variations in μ, more so than the cross-polar cap potential. This may be the case for geomagnetic activity too.

Characteristics of ionospheric electron density profiles in the auroral and polar cap regions from long-term incoherent scatter radar observations

NASA Astrophysics Data System (ADS)

Jee, G.; Kim, E.; Kwak, Y. S.; Kim, Y.; Kil, H.

2017-12-01

We investigate the climatological characteristics of the ionospheric electron density profiles in the auroral and polar cap regions in comparison with the mid-latitude ionosphere using incoherent scatter radars (ISR) observations from Svalbard (78.15N, 16.05E), Tromso (69.59N, 19.23E), and Millstone Hill (42.6N, 288.5E) during a period of 1995 - 2015. Diurnal variations of electron density profiles from 100 to 500 km are compared among the three radar observations during equinox, summer and winter solstice for different solar and geomagnetic activities. Also investigated are the physical characteristics of E-region and F-region peak parameters of electron density profiles in the auroral and polar cap regions, which are significantly different from the mid-latitude ionosphere. In the polar ionosphere, the diurnal variations of density profiles are extremely small in summer hemisphere. Semiannual anomaly hardly appears for all latitudes, but winter anomaly occurs at mid-latitude and auroral ionospheres for high solar activity. Nighttime density becomes larger than daytime density in the winter polar cap ionosphere for high solar activity. The E-region peak is very distinctive in the nighttime auroral region and the peak height is nearly constant at about 110 km for all conditions. Compared with the F-region peak density, the E-region peak density does not change much with solar activity. Furthermore, the E-region peak density can be even larger than F-region density for low solar activity in the auroral region, particularly during disturbed condition.

Polar Rain Gradients and Field-Aligned Polar Cap Potentials

NASA Technical Reports Server (NTRS)

Fairfield, D. H.; Wing, S.; Newell, P. T.; Ruohoniemi, J. M.; Gosling, J. T.; Skoug, R. M.

2008-01-01

ACE SWEPAM measurements of solar wind field-aligned electrons have been compared with simultaneous measurements of polar rain electrons precipitating over the polar cap and detected by DMSP spacecraft. Such comparisons allow investigation of cross-polarcap gradients in the intensity of otherwise-steady polar rain. The generally good agreement of the distribution functions, f, from the two data sources confirms that direct entry of solar electrons along open field lines is indeed the cause of polar rain. The agreement between the data sets is typically best on the side of the polar cap with most intense polar rain but the DMSP f's in less intense regions can be brought into agreement with ACE measurements by shifting all energies by a fixed amounts that range from tens to several hundred eV. In most cases these shifts are positive which implies that field-aligned potentials of these amounts exist on polar cap field lines which tend to retard the entry of electrons and produce the observed gradients. These retarding potentials undoubtedly appear in order to prevent the entry of low-energy electrons and maintain charge quasi-neutrality that would otherwise be violated since most tailward flowing magnetosheath ions are unable to follow polar rain electrons down to the polar cap. In more limited regions near the boundary of the polar cap there is sometimes evidence for field-aligned potentials of the opposite sign that accelerate polar rain electrons. A solar electron burst is also studied and it is concluded that electrons from such bursts can enter the magnetotail and precipitate in the same manner as polar rain.

Heat treatment of bulk gallium arsenide using a phosphosilicate glass cap

NASA Technical Reports Server (NTRS)

Mathur, G.; Wheaton, M. L.; Borrego, J. M.; Ghandhi, S. K.

1985-01-01

n-type bulk GaAs crystals, capped with chemically vapor-deposited phosphosilicate glass, were heat treated at temperatures in the range of 600 to 950 C. Measurements on Schottky diodes and solar cells fabricated on the heat-treated material, after removal of a damaged surface layer, show an increase in free-carrier concentration, in minority-carrier-diffusion length, and in solar-cell short-circuit current. The observed changes are attributed to a removal of lifetime-reducing acceptorlike impurities, defects, or their complexes.

Focusing the Sun: State Considerations for Designing Community Solar Policy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, Jeffrey J; Shah, Monisha R

This report summarizes outcomes from the National Community Solar Partnership State Best Practices working group by identifying key differences in state policies that enable community solar and illustrating how various policy design approaches may impact the market. For the latter question, it is too early to quantify a relationship between policy design and market impacts, because most state programs have not been fully implemented. So, the authors conducted interviews with 19 subject matter experts, including project developers, regulators, and utilities to better understand how various policy design approaches may impact community solar markets. These perspectives, along with those gleaned frommore » the working group and relevant literature were synthesized to identify key considerations for policymakers designing community solar programs. Though state community solar policies vary in numerous ways, the report focuses on the following critical elements: program cap, project size cap, subscriber location requirements, subscriber eligibility requirements, low- and moderate-income stipulations, and subscriber compensation.« less

Investigating Mars South Residual CO2 Cap with a Global Climate Model

NASA Technical Reports Server (NTRS)

Kahre, M. A.; Dequaire, J.; Hollingsworth, J. L.; Haberle, R. M.

2016-01-01

The CO2 cycle is one of the three controlling climate cycles on Mars. One aspect of the CO2 cycle that is not yet fully understood is the existence of a residual CO2 ice cap that is offset from the south pole. Previous investigations suggest that the atmosphere may control the placement of the south residual cap (e.g., Colaprete et al., 2005). These investigations show that topographically forced stationary eddies in the south during southern hemisphere winter produce colder atmospheric temperatures and increased CO2 snowfall over the hemisphere where the residual cap resides. Since precipitated CO2 ice produces higher surface albedos than directly deposited CO2 ice, it is plausible that CO2 snowfall resulting from the zonally asymmetric atmospheric circulation produces surface ice albedos high enough to maintain a residual cap only in one hemisphere. The goal of the current work is to further evaluate Colaprete et al.'s hypothesis by investigating model-predicted seasonally varying snowfall patterns in the southern polar region and the atmospheric circulation components that control them.

Cu mesh for flexible transparent conductive electrodes.

PubMed

Kim, Won-Kyung; Lee, Seunghun; Hee Lee, Duck; Hee Park, In; Seong Bae, Jong; Woo Lee, Tae; Kim, Ji-Young; Hun Park, Ji; Chan Cho, Yong; Ryong Cho, Chae; Jeong, Se-Young

2015-06-03

Copper electrodes with a micromesh/nanomesh structure were fabricated on a polyimide substrate using UV lithography and wet etching to produce flexible transparent conducting electrodes (TCEs). Well-defined mesh electrodes were realized through the use of high-quality Cu thin films. The films were fabricated using radio-frequency (RF) sputtering with a single-crystal Cu target--a simple but innovative approach that overcame the low oxidation resistance of ordinary Cu. Hybrid Cu mesh electrodes were fabricated by adding a capping layer of either ZnO or Al-doped ZnO. The sheet resistance and the transmittance of the electrode with an Al-doped ZnO capping layer were 6.197 ohm/sq and 90.657%, respectively, and the figure of merit was 60.502 × 10(-3)/ohm, which remained relatively unchanged after thermal annealing at 200 °C and 1,000 cycles of bending. This fabrication technique enables the mass production of large-area flexible TCEs, and the stability and high performance of Cu mesh hybrid electrodes in harsh environments suggests they have strong potential for application in smart displays and solar cells.

Association between bortezomib dose intensity and overall survival in mantle cell lymphoma patients on frontline VR-CAP in the phase 3 LYM-3002 study.

PubMed

Robak, Tadeusz; Huang, Huiqiang; Jin, Jie; Zhu, Jun; Liu, Ting; Samoilova, Olga; Pylypenko, Halyna; Verhoef, Gregor; Siritanaratkul, Noppadol; Osmanov, Evgenii; Pereira, Juliana; Mayer, Jiri; Hong, Xiaonan; Okamoto, Rumiko; Pei, Lixia; Rooney, Brendan; van de Velde, Helgi; Cavalli, Franco

2017-06-05

The pivotal LYM-3002 study compared frontline rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) with bortezomib, rituximab, cyclophosphamide, doxorubicin and prednisone (VR-CAP) in newly diagnosed mantle cell lymphoma (MCL) patients for whom stem cell transplantation was not an option. This post hoc subanalysis of the VR-CAP data from LYM-3002 evaluated the effect of bortezomib dose intensity on OS in patients who completed ≥6 cycles of treatment. From the end of cycle 6, patients receiving ≥4.6 mg/m 2 /cycle of bortezomib had significantly longer OS (but not PFS) compared with those receiving <4.6 mg/m 2 /cycle by univariate analysis (HR 0.43 [95% CI: 0.23-0.80]; p = .0059). This association remained significant in multivariate analysis adjusting for baseline patient and disease characteristics (HR 0.40 [95% CI: 0.20-0.79]; p = .008]. Higher bortezomib dose intensity was the strongest predictor of OS in newly diagnosed MCL patients receiving VR-CAP. Clinicaltrials.gov identifier: NCT00722137.

The white dwarf companion of the B a 2 star zeta Cap

NASA Technical Reports Server (NTRS)

Boehm-Vitense, E.

1981-01-01

The Ba II star zeta Cap has a white dwarf companion. Its T (sub eff) is determined to be 22000 K, its mass is approximately one solar mass. The importance of this finding for the explanation of abundance peculiarities is discussed.

The solar cycle; Proceedings of the National Solar Observatory/Sacramento Peak 12th Summer Workshop, Sunspot, NM, Oct. 15-18, 1991

NASA Technical Reports Server (NTRS)

Harvey, Karen L. (Editor)

1992-01-01

Attention is given to a flux-transport model, the effect of fractal distribution on the evolution of solar surface magnetic fields, active nests on the sun, magnetic flux transport in solar active regions, recent advances in stellar cycle research, magnetic intermittency on the sun, a search for existence of large-scale motions on the sun, and new solar cycle data from the NASA/NSO spectromagnetograph. Attention is also given to the solar cycle variation of coronal temperature during cycle 22, the distribution of the north-south asymmetry for the various activity cycles, solar luminosity variation, a two-parameter model of total solar irradiance variation over the solar cycle, the origin of the solar cycle, nonlinear feedbacks in the solar dynamo, and long-term dynamics of the solar cycle.

The hemispherical asymmetry of the residual polar caps on Mars

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1991-01-01

A model of the polar caps of Mars was created which allows: (1) for light penetration into the cap; (2) ice albedo to vary with age, latitude, hemisphere, dust content, and solar zenith angle; and (3) for diurnal variability. The model includes the radiative effects of clouds and dust, and heat transport as represented by a thermal wind. The model reproduces polar cap regression data very well, including the survival of CO2 frost at the south pole and reproduces the general trend in the Viking Lander pressure data.

New Hampshire | Midmarket Solar Policies in the United States | Solar

Science.gov Websites

implemented. New Hampshire Public Utilities Commission's (NHPUC) administers a rebate program for commercial Administrator Incentive Commercial & Industrial Solar Incentive Program New Hampshire Public Utilities $0.25/W rebate for residential systems $0.25/W rebate for commercial/government systems Capped at $1,375

Glass diffusion source for constraining BSF region of a solar cell

DOEpatents

Lesk, I.A.; Pryor, R.A.; Coleman, M.G.

1982-08-27

The present invention is directed to a method of fabricating a solar cell comprising simultaneous diffusion of the p and n dopant materials into the solar cell substrate. The simultaneous diffusion process is preceded by deposition of a capping layer impervious to doping by thermal diffusion processes.

Variations in Solar Parameters and Cosmic Rays with Solar Magnetic Polarity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oh, S.; Yi, Y., E-mail: suyeonoh@jnu.ac.kr

The sunspot number varies with the 11-year Schwabe cycle, and the solar magnetic polarity reverses every 11 years approximately at the solar maximum. Because of polarity reversal, the difference between odd and even solar cycles is seen in solar activity. In this study, we create the mean solar cycle expressed by phase using the monthly sunspot number for all solar cycles 1–23. We also generate the mean solar cycle for sunspot area, solar radio flux, and cosmic ray flux within the allowance of observational range. The mean solar cycle has one large peak at solar maximum for odd solar cyclesmore » and two small peaks for most even solar cycles. The odd and even solar cycles have the statistical difference in value and shape at a confidence level of at least 98%. For solar cycles 19–23, the second peak in the even solar cycle is larger than the first peak. This result is consistent with the frequent solar events during the declining phase after the solar maximum. The difference between odd and even solar cycles can be explained by a combined model of polarity reversal and solar rotation. In the positive/negative polarity, the polar magnetic field introduces angular momentum in the same/opposite direction as/to the solar rotation. Thus the addition/subtraction of angular momentum can increase/decrease the motion of plasma to support the formation of sunspots. Since the polarity reverses at the solar maximum, the opposite phenomenon occurs in the declining phase.« less

The Mars water cycle at other epochs: Recent history of the polar caps and layered terrain

NASA Technical Reports Server (NTRS)

Jakosky, Bruce M.; Henderson, Bradley G.; Mellon, Michael T.

1992-01-01

The Martian polar caps and layered terrain presumably evolves by the deposition and removal of small amounts of water and dust each year, the current cap attributes therefore represent the incremental transport during a single year as integrated over long periods of time. The role was studied of condensation and sublimation of water ice in this process by examining the seasonal water cycle during the last 10(exp 7) yr. In the model, axial obliquity, eccentricity, and L sub s of perihelion vary according to dynamical models. At each epoch, the seasonal variations in temperature are calculated at the two poles, keeping track of the seasonal CO2 cap and the summertime sublimation of water vapor into the atmosphere; net exchange of water between the two caps is calculated based on the difference in the summertime sublimation between the two caps (or on the sublimation from one cap if the other is covered with CO2 frost all year). Results from the model can help to explain (1) the apparent inconsistency between the timescales inferred for layer formation and the much older crater retention age of the cap and (2) the difference in sizes of the two residual caps, with the south being smaller than the north.

Advanced solar irradiances applied to satellite and ionospheric operational systems

NASA Astrophysics Data System (ADS)

Tobiska, W. Kent; Schunk, Robert; Eccles, Vince; Bouwer, Dave

Satellite and ionospheric operational systems require solar irradiances in a variety of time scales and spectral formats. We describe the development of a system using operational grade solar irradiances that are applied to empirical thermospheric density models and physics-based ionospheric models used by operational systems that require a space weather characterization. The SOLAR2000 (S2K) and SOLARFLARE (SFLR) models developed by Space Environment Technologies (SET) provide solar irradiances from the soft X-rays (XUV) through the Far Ultraviolet (FUV) spectrum. The irradiances are provided as integrated indices for the JB2006 empirical atmosphere density models and as line/band spectral irradiances for the physics-based Ionosphere Forecast Model (IFM) developed by the Space Environment Corporation (SEC). We describe the integration of these irradiances in historical, current epoch, and forecast modes through the Communication Alert and Prediction System (CAPS). CAPS provides real-time and forecast HF radio availability for global and regional users and global total electron content (TEC) conditions.

Obliquity variation in a Mars climate evolution model

NASA Technical Reports Server (NTRS)

Tyler, D.; Haberle, Robert M.

1993-01-01

The existence of layered terrain in both polar regions of Mars is strong evidence supporting a cyclic variation in climate. It has been suggested that periods of net deposition have alternated with periods of net erosion in creating the layered structure that is seen today. The cause for this cyclic climatic behavior is variation in the annually averaged latitudinal distribution of solar insolation in response to obliquity cycles. For Mars, obliquity variation leads to major climatological excursion due to the condensation and sublimation of the major atmospheric constituent, CO2. The atmosphere will collapse into the polar caps, or existing caps will rapidly sublimate into the atmosphere, dependent upon the polar surface heat balance and the direction of the change in obliquity. It has been argued that variations in the obliquity of Mars cause substantial departures from the current climatological values of the surface pressure and the amount of CO2 stored in both the planetary regolith and polar caps. In this new work we have modified the Haberle et al. model to incorporate variable obliquity by allowing the polar and equatorial insolation to become functions of obliquity, which we assume to vary sinusoidally in time. As obliquity varies in the model, there can be discontinuities in the time evolution of the model equilibrium values for surface pressure, regolith, and polar cap storage. The time constant, tau r, for the regolith to find equilibrium with the climate is estimated--depending on the depth, thermal conductivity, and porosity of the regolith--between 10(exp 4) and 10(exp 6) yr. Thus, using 2000-yr timesteps to move smoothly through the 0.1250 m.y. obliquity cycles, we have an atmosphere/regolith system that cannot be assumed in equilibrium. We have dealt with this problem by limiting the rate at which CO2, can move between the atmosphere and regolith, mimicking the diffusive nature and effects of the temperature and pressure waves, by setting the time rate of change of regolith storage proportional to the difference between equilibrium storage and current storage.

Investigation of advanced nanostructured multijunction photoanodes for enhanced solar hydrogen generation via water splitting

NASA Astrophysics Data System (ADS)

Ishihara, Hidetaka

As the worldwide demand for fossil-based fuel increases every day and the fossil reserve continues to be depleted, the need for alternative/renewable energy sources has gained momentum. Electric, hybrid, and hydrogen cars have been at the center of discussion lately among consumers, automobile manufacturers, and politicians, alike. The development of a fuel-cell based engine using hydrogen has been an ambitious research area over the last few decades-ever since Fujishima showed that hydrogen can be generated via the solar-energy driven photo-electrolytic splitting of water. Such solar cells are known as Photo-Electro-Chemical (PEC) solar cells. In order to commercialize this technology, various challenges associated with photo-conversion efficiency, chemical corrosion resistance, and longevity need to be overcome. In general, metal oxide semiconductors such as titanium dioxide (TiO 2, titania) are excellent candidates for PEC solar cells. Titania nanotubes have several advantages, including biocompatibility and higher chemical stability. Nevertheless, they can absorb only 5-7% of the solar spectrum which makes it difficult to achieve the higher photo-conversion efficiency required for successful commercial applications. A two-prong approach was employed to enhance photo-conversion efficiency: 1) surface modification of titania nanotubes using plasma treatment and 2) nano-capping of the titania nanotubes using titanium disilicide. The plasma surface treatment with N2 was found to improve the photo-current efficiency of titania nanotubes by 55%. Similarly, a facile, novel approach of nano-capping titania nanotubes to enhance their photocurrent response was also investigated. Electrochemically anodized titania nanotubes were capped by coating a 25 nm layer of titanium disilicide using RF magnetron sputtering technique. The optical properties of titania nanotubes were not found to change due to the capping; however, a considerable increase (40%) in the photocurrent density was observed for the nano-capped titania nanotubes due to the enhanced charge transfer process. Similarly, another metal oxide semiconductor was investigated tungsten trioxide (WO3), which has a much higher absorption capability (12%) in the solar spectrum. The WO3 porous nanostructures suffered from surface corrosion resulting in a large reduction in the photocurrent density as a function of time in the alkaline electrolytes. However, with a protective coating of Indium Tin Oxide (100 nm), the surface corrosion of WO3 porous nanostructures was reduced. A large increase in the photocurrent density of as much as 340% was observed after the ITO was applied to the WO3 porous nanostructures

Changes in the Martian Circulation and Climate in Response to Orbital Parameter Variations

NASA Astrophysics Data System (ADS)

Richardson, M. I.; Wilson, R. J.

2000-10-01

Martian orbital parameters are known to vary on time scales greater than 105 years. Such variations, especially in obliquity, have important consequences for the spatial distribution of solar heating of the surface and atmosphere, and hence are expected to affect some form of quasi-periodic climate change. The impact of changing obliquity on surface temperatures, and hence on volatile stability have been widely addressed. However, the changing insolation patterns should also modify the circulation of the atmosphere. As the nature and rate of volatile transport, and the vigour of dust lifting and transport from the surface are critical aspects of the climate, the circulation response to orbital variations needs to be assessed. In this presentation, we show results from the Geophysical Fluid Dynamics Laboratory (GFDL) Mars General Circulation Model (GCM) in which the orbit of Mars has been varied: obliquities between 0 and 60, perihelion passage between Ls=70 and 250, and eccentricities between 0 and 0.12. In general, the total atmosphere and cap CO2 budget is held constant (i.e. we assume no exchange with the regolith), and that the rate of dust supply into the lowest model level remains constant. The impact of these assumptions are examined. Many of the anticipated changes in circulation are found to occur as obliquity is increased from 0: The Hadley cell strength and that of the winter polar jet are found to increase; The magnitude of the seasonal CO2 cycle increases, resulting in extensive seasonal ice caps; Surface winds strengthen resulting in greater surface stresses and likely stronger dust lifting; The cycle of water becomes more vigourous, with large column vapour amounts in the polar regions corresponding to higher cap surface temperatures. However, some results contrast with expectations: Although the surface wind strengths change with orbital parameters, the mean directions tend not to, with implications for aeolian geological features; Even at low obliquity, the model does not develop a permanent CO2 ice cap at either pole (this likely reflects the fact that uniform and non-varying ice properties are gravely inadequate to realistically simulate Martian polar ices); Water ice deposits do not stabilize at the equator, even at high obliquity - instead they slosh backwards-and-forwards between the seasonal ice caps, as they do at present. We note that the southern summer Hadley circulation remains the dominant cell when integrated over the annual cycle, even when the timing of perihelion passage is varied by 180 degrees. We suggest that this reflects the greater importance of the global topographic dichotomy for the strength of the mean meridional circulation over that of eccentricity.

Natural dye extracted from karkadah and its application in dye-sensitized solar cells: experimental and density functional theory study.

PubMed

Reda, S M; Soliman, K A

2016-02-01

This work presents an experimental and theoretical study of cyanidin natural dye as a sensitizer for ZnO dye-sensitized solar cells. ZnO nanoparticles were prepared using ammonia and oxalic acid as a capping agent. The calculated average size of the synthesized ZnO with different capping agents was found to be 32.1 nm. Electronic properties of cyanidin and delphinidin dye were studied using density functional theory (DFT) and time-dependent DFT with a B3LYP/6-31G(d,p) level. By comparing the theoretical results with the experimental data, the cyanidin dye can be used as a sensitizer in dye-sensitized solar cells. An efficiency of 0.006% under an AM-1.5 illumination at 100  mW/cm(2) was attained. The influence of dye adsorption time on the solar cell performance is discussed.

Analysis of proton and electron spectrometer data from OGO-5 spacecraft

NASA Technical Reports Server (NTRS)

Pomerantz, M. A.

1975-01-01

The interaction between the geomagnetic and interplanetary magnetic fields is studied through its effects upon the intensities of solar electrons reaching the polar caps during times of strongly anisotropic electron fluxes in the magnetosheath. During the particle event of November 18, 1968, electrons of solar origin were observed outside the magnetopause with detectors aboard OGO-5. Correlative studies of these satellite observations and concurrent measurements by riometers and ionospheric forward scatter systems in both polar regions revealed that the initial stage of the associated polar cap absorption event is attributable to the arrival of solar electrons. Evidence of a north-south asymmetry in the solar electron flux, at a time when the interplanetary magnetic field vector was nearly parallel with the ecliptic plane, supports an open magnetospheric model. The analysis indicates that an anisotropic electron flux may be isotropized at the magnetopause before propagating into the polar regions.

Phase I/II combined chemoimmunotherapy with carcinoembryonic antigen-derived HLA-A2-restricted CAP-1 peptide and irinotecan, 5-fluorouracil, and leucovorin in patients with primary metastatic colorectal cancer.

PubMed

Weihrauch, Martin R; Ansén, Sascha; Jurkiewicz, Elke; Geisen, Caroline; Xia, Zhinan; Anderson, Karen S; Gracien, Edith; Schmidt, Manuel; Wittig, Burghardt; Diehl, Volker; Wolf, Juergen; Bohlen, Heribert; Nadler, Lee M

2005-08-15

We conducted a phase I/II randomized trial to evaluate the clinical and immunologic effect of chemotherapy combined with vaccination in primary metastatic colorectal cancer patients with a carcinoembryonic antigen-derived peptide in the setting of adjuvants granulocyte macrophage colony-stimulating factor, CpG-containing DNA molecules (dSLIM), and dendritic cells. HLA-A2-positive patients with confirmed newly diagnosed metastatic colorectal cancer and elevated serum carcinoembryonic antigen (CEA) were randomized to receive three cycles of standard chemotherapy (irinotecan/high-dose 5-fluorouracil/leucovorin) and vaccinations with CEA-derived CAP-1 peptide admixed with different adjuvants [CAP-1/granulocyte macrophage colony-stimulating factor/interleukin-2 (IL-2), CAP-1/dSLIM/IL-2, and CAP-1/IL-2]. After completion of chemotherapy, patients received weekly vaccinations until progression of disease. Immune assessment was done at baseline and after three cycles of combined chemoimmunotherapy. HLA-A2 tetramers complexed with the peptides CAP-1, human T-cell lymphotrophic virus type I TAX, cytomegalovirus (CMV) pp65, and EBV BMLF-1 were used for phenotypic immune assessment. IFN-gamma intracellular cytokine assays were done to evaluate CTL reactivity. Seventeen metastatic patients were recruited, of whom 12 completed three cycles. Therapy resulted in five complete response, one partial response, five stable disease, and six progressive disease. Six grade 1 local skin reactions and one mild systemic reaction to vaccination treatment were observed. Overall survival after a median observation time of 29 months was 17 months with a survival rate of 35% (6 of 17) at that time. Eight patients (47%) showed elevation of CAP-1-specific CTLs. Neither of the adjuvants provided superiority in eliciting CAP-1-specific immune responses. During three cycles of chemotherapy, EBV/CMV recall antigen-specific CD8+ cells decreased by an average 14%. The presented chemoimmunotherapy is a feasible and safe combination therapy with clinical and immunologic efficacy. Despite concurrent chemotherapy, increases in CAP-1-specific T cells were observed in 47% of patients after vaccination.

The Mars water cycle at other epochs - Recent history of the polar caps and layered terrain

NASA Technical Reports Server (NTRS)

Jakosky, Bruce M.; Henderson, Bradley G.; Mellon, Michael T.

1993-01-01

A numerical model is presented of the integrated role of seasonal water cycle on the evolution of polar deposits on Mars over the last 10 million years. From the model, it is concluded that the only major difference between the polar caps which affects their long-term behavior is ultimately the difference in their elevations. Because of that difference, there is a preference for CO2 frost to stay longer on the northern polar cap. The average difference in sublimation at the caps results in a net south-to-north transport of water ice over long time scales. Superimposed on any long-term behavior is a transfer of water ice between the caps on the 10 exp 5 - 10 exp 6 yr time scales. The amount of water exchanged is small compared to the total ice content of the polar deposits.

The Mars water cycle at other epochs - Recent history of the polar caps and layered terrain

NASA Astrophysics Data System (ADS)

Jakosky, B. M.; Henderson, B. G.; Mellon, M. T.

1993-04-01

A numerical model is presented of the integrated role of seasonal water cycle on the evolution of polar deposits on Mars over the last 10 million years. From the model, it is concluded that the only major difference between the polar caps which affects their long-term behavior is ultimately the difference in their elevations. Because of that difference, there is a preference for CO2 frost to stay longer on the northern polar cap. The average difference in sublimation at the caps results in a net south-to-north transport of water ice over long time scales. Superimposed on any long-term behavior is a transfer of water ice between the caps on the 10 exp 5 - 10 exp 6 yr time scales. The amount of water exchanged is small compared to the total ice content of the polar deposits.

Arizona | Midmarket Solar Policies in the United States | Solar Research |

Science.gov Websites

standard. Arizona has a net-metering program with no size limit but is specific to the customer's load % of customer's total connected load Aggregate cap: Not addressed Credit: Net excess generation is are exempt from Arizona Corporation Commission regulation. Community Solar There are currently no

Maryland | Midmarket Solar Policies in the United States | Solar Research |

Science.gov Websites

(RECs). Meter aggregation: Virtual net metering is allowed for agricultural customers, non-profits, and solar PV technology. Mathias Agricultural Energy Efficiency Grant Program Maryland Energy Administration Farms and agricultural businesses are eligible for grants of up to 50% of the system cost, capped at

Impact of the Geoplasma on a Spaceborne GPS(Global Positioning System) Receiver System - A Preliminary Study

DTIC Science & Technology

1989-02-28

valug vhich *dvrivv the A044 1 hý’we not met with mucth suktflV. Klobutchsr Ot al (1987) have obtained ThC data for tho first ti=# "t a polar cap sit...ntudy in 1984. found teei s vaiblty int TE. as-pri trainsg of ehnmntof the -ardor of J-O1gtffs~ fltpt riqd4 al ghlort a; tpný mrl’seO Were nbtrvud... ALE ) THEN ENC - V3 * ZEC ELSE EAR - (SIN (P1(3) - ALH) * 2.92) **6 F3 - EXP (- EAR) "V3 - V3 * F3 F3 - 1.0 - F3C* C* S3 - SOLAR CYCLE FUNCTION IF(1.1

Selective layer disordering in III-nitrides with a capping layer

DOEpatents

Wierer, Jr., Jonathan J.; Allerman, Andrew A.

2016-06-14

Selective layer disordering in a doped III-nitride superlattice can be achieved by depositing a dielectric capping layer on a portion of the surface of the superlattice and annealing the superlattice to induce disorder of the layer interfaces under the uncapped portion and suppress disorder of the interfaces under the capped portion. The method can be used to create devices, such as optical waveguides, light-emitting diodes, photodetectors, solar cells, modulators, laser, and amplifiers.

Intense Geomagnetic Storms of Solar Cycle 24 and Associated Energetics

NASA Astrophysics Data System (ADS)

Rawat, R.; Echer, E.; Gonzalez, W. D.

2013-12-01

Solar cycle 24 commenced in November 2008 following a deep solar minimum. The solar activity picked up gradually and consequently led to increase in geomagnetic activity during the ascending phase of new cycle. From the start of this cycle till July 2013, only 12 intense geomagnetic storms (Dst < -100 nT) have occurred. We investigate the solar wind-interplanetary drivers for these intense geomagnetic storms using satellite data. Total energy Poynting flux (ɛ) representing the fraction of solar wind energy transferred into the magnetosphere during different storms will be calculated. Solar cycle 24 is weaker as compared to previous solar cycle (23). In this work, a comparative study of solar and geomagnetic signatures during the ascending phase of the two cycles will be carried out.

Hawaii | Midmarket Solar Policies in the United States | Solar Research |

Science.gov Websites

net excess generation compensation. Hawaii provides commercial system owners with a 35% tax credit. It of Taxation Commercial system owners are eligible for a tax credit worth 35% of the system's value . The Hawaii tax credit is capped at $500,000 for commercial properties. Solar system owners are also

Field-aligned current response to solar indices

NASA Astrophysics Data System (ADS)

Edwards, Thom R.; Weimer, D. R.; Tobiska, W. K.; Olsen, Nils

2017-05-01

Magnetometer data from three satellite missions have been used to analyze and identify the effects of varying solar radiation on the magnitudes and locations of field-aligned currents in the Earth's upper atmosphere. Data from the CHAMP, Ørsted, and Swarm satellite missions have been brought together to provide a database spanning a 15 year period. The extensive time frame has been augmented by data from the ACE satellite, as well as a number of indices of solar radiation. This data set has been sorted by a number of solar wind, interplanetary magnetic field, and solar radiation indices to provide measurements for the field-aligned current structures in both hemispheres for arbitrary seasonal tilts. In addition, routines have been developed to extract the total current for different regions of the current structures, including regions 0, 1, and 2. Results from this study have been used to evaluate the effects of variations in four different solar indices on the total current in different regions of the polar cap. While the solar indices do not have major influence on the total current of the polar cap when compared to solar wind and interplanetary magnetic field parameters, it does appear that there is a nonlinear response to increasing F10.7, M10.7, and S10.7 solar indices. Surprisingly, there appears to be a very linear response as Y10.7 solar index increases.

Status of Cycle 23 Forecasts

NASA Technical Reports Server (NTRS)

Hathaway, D. H.

2000-01-01

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 month- by-month description of future activity, while others, e.g., geomagnetic precursors, work well near solar minimum but provide an estimate only 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 precursor method gave a smoothed sunspot number maximum of 154+21 for cycle 23. A mathematical function dependent upon the time of cycle initiation and the cycle amplitude then describes the level of solar activity for the complete cycle. As the time of cycle maximum approaches a better estimate of the cycle activity is obtained by including the fit between recent activity levels and this function. This Combined Solar Cycle Activity Forecast now gives a smoothed sunspot maximum of 140+20 for cycle 23. 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.

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

NASA Astrophysics Data System (ADS)

Karna, Mahendra; Karna, Nishu

2017-08-01

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

The role of water ice clouds in the Martian hydrologic cycle

NASA Technical Reports Server (NTRS)

James, Philip B.

1990-01-01

A one-dimensional model for the seasonal cycle of water on Mars has been used to investigate the direction of the net annual transport of water on the planet and to study the possible role of water ice clouds, which are included as an independent phase in addition to ground ice and water vapor, in the cycle. The calculated seasonal and spatial patterns of occurrence of water ice clouds are qualitatively similar to the observed polar hoods, suggesting that these polar clouds are, in fact, an important component of water cycle. A residual dry ice in the south acts as a cold trap which, in the absence of sources other than the caps, will ultimately attract the water ice from the north cap; however, in the presence of a source of water in northern midlatitudes during spring, it is possible that the observed distribution of vapor and ice can be in a steady state even if a residual CO2 cap is a permanent feature of the system.

KSC-99pc05

NASA Image and Video Library

1999-01-03

KENNEDY SPACE CENTER, FLA. -- Amid clouds of exhaust, a Boeing Delta II expendable launch vehicle with NASA's Mars Polar Lander clears Launch Complex 17B, Cape Canaveral Air Station, after launch at 3:21:10 p.m. EST. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

KSC-99pc04

NASA Image and Video Library

1999-01-03

KENNEDY SPACE CENTER, FLA. -- Amid clouds of exhaust and into a gray-clouded sky , a Boeing Delta II expendable launch vehicle lifts off with NASA's Mars Polar Lander at 3:21:10 p.m. EST from Launch Complex 17B, Cape Canaveral Air Station. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

KSC-99pc06

NASA Image and Video Library

1999-01-03

KENNEDY SPACE CENTER, FLA. -- Silhouetted against the gray sky, a Boeing Delta II expendable launch vehicle with NASA's Mars Polar Lander lifts off from Launch Complex 17B, Cape Canaveral Air Station, at 3:21:10 p.m. EST. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

KSC-99pc03

NASA Image and Video Library

1999-01-03

KENNEDY SPACE CENTER, FLA. -- A Boeing Delta II expendable launch vehicle lifts off with NASA's Mars Polar Lander into a cloud-covered sky at 3:21:10 p.m. EST from Launch Complex 17B, Cape Canaveral Air Station. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

High latitude field aligned light ion flows in the topside ionosphere deduced from ion composition and plasma temperatures

NASA Technical Reports Server (NTRS)

Grebowsky, J. M.; Hoegy, W. R.; Chen, T. C.

1993-01-01

Using a comprehensive ionospheric data set comprised of all available ion composition and plasma temperature measurements from satellites, the vertical distributions of ion composition and plasma temperatures are defined from middle latitudes up into the polar cap for summer conditions for altitudes below about 1200 km. These data are sufficient to allow a numerical estimation of the latitudinal variation of the light ion outflows from within the plasmasphere to the polar wind regions. The altitude at which significant light ion outflow begins is found to be lower during solar minimum conditions than during solar maximum. The H(+) outward speeds are of the order of 1 km/s near 1100 km during solar maximum but attain several km/s speeds for solar minimum. He(+) shows a similar altitude development of flow but attains polar cap speeds much less than 1 km/s at altitudes below 1100 km, particularly under solar maximum conditions. Outward flows are also found in the topside F-region for noontime magnetic flux tubes within the plasmasphere.

Predictions of Solar Cycle 24: How are We Doing?

NASA Technical Reports Server (NTRS)

Pesnell, William D.

2016-01-01

Predictions of solar activity are an essential part of our Space Weather forecast capability. Users are requiring usable predictions of an upcoming solar cycle to be delivered several years before solar minimum. A set of predictions of the amplitude of Solar Cycle 24 accumulated in 2008 ranged from zero to unprecedented levels of solar activity. The predictions formed an almost normal distribution, centered on the average amplitude of all preceding solar cycles. The average of the current compilation of 105 predictions of the annual-average sunspot number is 106 +/- 31, slightly lower than earlier compilations but still with a wide distribution. Solar Cycle 24 is on track to have a below-average amplitude, peaking at an annual sunspot number of about 80. Our need for solar activity predictions and our desire for those predictions to be made ever earlier in the preceding solar cycle will be discussed. Solar Cycle 24 has been a below-average sunspot cycle. There were peaks in the daily and monthly averaged sunspot number in the Northern Hemisphere in 2011 and in the Southern Hemisphere in 2014. With the rapid increase in solar data and capability of numerical models of the solar convection zone we are developing the ability to forecast the level of the next sunspot cycle. But predictions based only on the statistics of the sunspot number are not adequate for predicting the next solar maximum. I will describe how we did in predicting the amplitude of Solar Cycle 24 and describe how solar polar field predictions could be made more accurate in the future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, T.E.; Han, C.H.; Kollman, V.H.

/sup 13/C NMR of isotopically enriched metabolites has been used to study the metabolism of Microbacterium ammoniaphilum, a bacterium which excretes large quantities of L-glutamic acid into the medium. Biosynthesis from 90% (1-/sup 13/C) glucose results in relatively high specificity of the label, with (2,4-/sup 13/C/sub 2/) glutamate as the major product. The predominant biosynthetic pathway for synthesis of glutamate from glucose was determined to be the Embden Meyerhof glycolytic pathway followed by P-enolpyruvate carboxylase and the first third of the Krebs cycle. Different metabolic pathways are associated with different correlations in the enrichment of the carbons, reflected in themore » spectrum as different /sup 13/C-/sup 13/C scalar multiplet intensities. Hence, intensity and /sup 13/C-/sup 13/C multiplet analysis allows quantitation of the pathways involved. Although blockage of the Krebs cycle at the ..cap alpha..-ketoglutarate dehydrogenase step is the basis for the accumulation of glutamate, significant Krebs cycle activity was found in glucose grown cells, and extensive Krebs cycle activity in cells metabolizing (1-/sup 13/C) acetate. In addition to the observation of the expected metabolites, the disaccharide ..cap alpha..,..cap alpha..-trehalose and ..cap alpha..,..beta..-glucosylamine were identified from the /sup 13/C NMR spectra.« less

Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veith-Wolf, Boris; Wang, Jianhui; Hannu-Kuure, Milja

2015-02-02

We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlO{sub x}) films, used for the rear surface passivation of high-efficiency crystalline silicon solar cells. We examine various siloxane-based liquid-phase-deposited (LPD) materials. Our optimized AlO{sub x}/LPD stacks show an excellent thermal and chemical stability against aluminum metal paste, as demonstrated by measured surface recombination velocities below 10 cm/s on 1.3 Ωcm p-type silicon wafers after firing in a belt-line furnace with screen-printed aluminum paste on top. Implementation of the optimized LPD layers into an industrial-type screen-printing solar cell process results in energy conversion efficiencies ofmore » up to 19.8% on p-type Czochralski silicon.« less

Reduction of the field-aligned potential drop in the polar cap during large geomagnetic storms

NASA Astrophysics Data System (ADS)

Kitamura, N.; Seki, K.; Nishimura, Y.; Hori, T.; Terada, N.; Ono, T.; Strangeway, R. J.

2013-12-01

We have studied photoelectron flows and the inferred field-aligned potential drop in the polar cap during 5 large geomagnetic storms that occurred in the periods when the photoelectron observations in the polar cap were available near the apogee of the FAST satellite (~4000 km) at solar maximum, and the footprint of the satellite paths in the polar cap was under sunlit conditions most of the time. In contrast to the ~20 V potential drop during geomagnetically quiet periods at solar maximum identified by Kitamura et al. [JGR, 2012], the field-aligned potential drop frequently became smaller than ~5 V during the main and early recovery phases of the large geomagnetic storms. Because the potential acts to inhibit photoelectron escape, this result indicates that the corresponding acceleration of ions by the field-aligned potential drop in the polar cap and the lobe region is smaller during the main and early recovery phases of large geomagnetic storms compared to during geomagnetically quiet periods. Under small field-aligned current conditions, the number flux of outflowing ions should be nearly equal to the net escaping electron number flux. Since ions with large flux originating from the cusp/cleft ionosphere convect into the polar cap during geomagnetic storms [e.g., Kitamura et al., JGR, 2010], the net escaping electron number flux should increase to balance the enhanced ion outflows. The magnitude of the field-aligned potential drop would be reduced to let a larger fraction of photoelectrons escape.

Prediction of Geomagnetic Activity and Key Parameters in High-latitude Ionosphere

NASA Technical Reports Server (NTRS)

Khazanov, George V.; Lyatsky, Wladislaw; Tan, Arjun; Ridley, Aaron

2007-01-01

Prediction of geomagnetic activity and related events in the Earth's magnetosphere and ionosphere are important tasks of US Space Weather Program. Prediction reliability is dependent on the prediction method, and elements included in the prediction scheme. Two of the main elements of such prediction scheme are: an appropriate geomagnetic activity index, and an appropriate coupling function (the combination of solar wind parameters providing the best correlation between upstream solar wind data and geomagnetic activity). We have developed a new index of geomagnetic activity, the Polar Magnetic (PM) index and an improved version of solar wind coupling function. PM index is similar to the existing polar cap PC index but it shows much better correlation with upstream solar wind/IMF data and other events in the magnetosphere and ionosphere. We investigate the correlation of PM index with upstream solar wind/IMF data for 10 years (1995-2004) that include both low and high solar activity. We also have introduced a new prediction function for the predicting of cross-polar-cap voltage and Joule heating based on using both PM index and upstream solar wind/IMF data. As we show such prediction function significantly increase the reliability of prediction of these important parameters. The correlation coefficients between the actual and predicted values of these parameters are approx. 0.9 and higher.

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.

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.

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.

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.

High Penetration Solar PV Deployment Sunshine State Solar Grid Initiative (SUNGRIN)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meeker, Rick; Steurer, Mischa; Faruque, MD Omar

The report provides results from the Sunshine State Solar Grid Initiative (SUNGRIN) high penetration solar PV deployment project led by Florida State University’s (FSU) Center for Advanced Power Systems (CAPS). FSU CAPS and industry and university partners have completed a five-year effort aimed at enabling effective integration of high penetration levels of grid-connected solar PV generation. SUNGRIN has made significant contributions in the development of simulation-assisted techniques, tools, insight and understanding associated with solar PV effects on electric power system (EPS) operation and the evaluation of mitigation options for maintaining reliable operation. An important element of the project was themore » partnership and participation of six major Florida utilities and the Florida Reliability Coordinating Council (FRCC). Utilities provided details and data associated with actual distribution circuits having high-penetration PV to use as case studies. The project also conducted foundational work supporting future investigations of effects at the transmission / bulk power system level. In the final phase of the project, four open-use models with built-in case studies were developed and released, along with synthetic solar PV data sets, and tools and techniques for model reduction and in-depth parametric studies of solar PV impact on distribution circuits. Along with models and data, at least 70 supporting MATLAB functions have been developed and made available, with complete documentation.« less

Using the Solar Polar Magnetic Field for Longterm Predictions of Solar Activity, Solar Cycles 21-25

NASA Astrophysics Data System (ADS)

Pesnell, W. D.; Schatten, K. H.

2017-12-01

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 amplification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, to 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. We will show how effective the SODA Index has been in predicting Solar Cycles 23 and 24, and present a unified picture of earlier estimates of the polar magnetic configuration in Solar Cycle 21 and 22. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 125 ± 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 70 ± 25. This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. Since the current approach uses data prior to solar minimum, these estimates may improve when the upcoming solar minimum is reached.

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 wind composition, aa, and the IMF strength, respectively, with corresponding figures of approx. 22%, approx. 32%, and approx. 25% for CME-related structures, and approx. 33%, approx. 19%, and approx. 33% for slow solar wind.

Analysis of regression methods for solar activity forecasting

NASA Technical Reports Server (NTRS)

Lundquist, C. A.; Vaughan, W. W.

1979-01-01

The paper deals with the potential use of the most recent solar data to project trends in the next few years. Assuming that a mode of solar influence on weather can be identified, advantageous use of that knowledge presumably depends on estimating future solar activity. A frequently used technique for solar cycle predictions is a linear regression procedure along the lines formulated by McNish and Lincoln (1949). The paper presents a sensitivity analysis of the behavior of such regression methods relative to the following aspects: cycle minimum, time into cycle, composition of historical data base, and unnormalized vs. normalized solar cycle data. Comparative solar cycle forecasts for several past cycles are presented as to these aspects of the input data. Implications for the current cycle, No. 21, are also given.

Nature and Stability of the Martian Seasonal Water Cycle

NASA Astrophysics Data System (ADS)

Richardson, M. I.; Wilson, R. J.

2001-12-01

Which components control the contemporary water cycle and what is the nature of the control mechanisms? These questions are at the heart of understanding how the Martian exchangeable water budget adjusts to perturbations and changes in the climate system. Analysis of a water cycle model embedded in the GFDL Mars GCM provides a paradigm for the water cycle as a feedback system, providing information on the important control points and response times. Much information on this system derives from monitoring the evolution towards steady state--one that resembles the observed water vapour and ice cloud distributions. The most important exchange balance in the system is that between the northern polar atmosphere and the rest of the planet. As the major net source for water, the northern residual water ice cap is active during summer, in the window of time between the sublimation and recondensation of the seasonal CO2 cap. At this time, water is exported from the northern polar atmosphere at a rate determined by the mixing capacity of the atmosphere and the amount of water held in the polar atmosphere. The latter is determined by the cap surface temperature. During the remainder of the year, water is returned to the pole. This return flux is determined by the atmospheric mixing capacity and the amount of water vapour held in the tropical and winter extratropical atmosphere. Steady-state is achieved when these fluxes balance. For a given climate state (and a roughly repeatable annual cycle of mixing), the outflux and influx of polar water are controlled by separate variables. Holding the cap temperature constant, the outflux will remain constant. Any perturbation to the global water budget will result in a change in the return flux that tends to oppose the sense of the perturbation--the perturbation will be damped. In the same way, a change in cap temperature (e.g. associated with a change in albedo) will result in changed water outflow. Again, this will tend to change the non-polar water vapour budget and hence the polar water influx so as to develop a new steady-state. It is important to note that only in this case is the steady-state global humidity changed: a given cap temperature and seasonal cycle of mixing capacity specifies a bulk steady-state atmospheric humidity. In all cases, the regolith acts as a damper on the system and adjusts to the global water distribution dictated ultimately by the northern cap. The model also suggests fast adjustment times, on order decades. A number of factors can affect atmospheric mixing capacity. As climate forcing factors change (associated with obliquity or greenhouse gas loading) the mixing capacity will change--an area for future study. The current mixing capacity of the atmosphere is also different from one that would obtain without atmospheric water condensation and sedimentation. Model clouds play important roles in returning water to the residual ice cap in northern summer, and significantly altering interhemispheric transport from that which would occur without clouds. As with previous studies, the southern polar cap acts as a permanent sink for water. The model and resulting paradigm for the water cycle can be used in very preliminary studies of past climate states. Forcing the model with an obliquity of 45 deg., the seasonal water ice caps become significantly more extended, reaching into the summer hemisphere. In fact, the seasonal caps "overlap" in the northern tropics, generating a year-round surface ice belt. Much work remains to be done in understanding water ice transport and exchange processes before models of paleoclimate can be of widespread utility--of which analysis of data from MGS and future missions will be key.

The MSFC Solar Activity Future Estimation (MSAFE) Model

NASA Technical Reports Server (NTRS)

Suggs, Ronnie J.

2017-01-01

The MSAFE model provides forecasts for the solar indices SSN, F10.7, and Ap. These solar indices are used as inputs to many space environment models used in orbital spacecraft operations and space mission analysis. Forecasts from the MSAFE model are provided on the MSFC Natural Environments Branch's solar webpage and are updated as new monthly observations come available. The MSAFE prediction routine employs a statistical technique that calculates deviations of past solar cycles from the mean cycle and performs a regression analysis to predict the deviation from the mean cycle of the solar index at the next future time interval. The prediction algorithm is applied recursively to produce monthly smoothed solar index values for the remaining of the cycle. The forecasts are initiated for a given cycle after about 8 to 12 months of observations are collected. A forecast made at the beginning of cycle 24 using the MSAFE program captured the cycle fairly well with some difficulty in discerning the double peak that occurred at solar cycle maximum.

The MSFC Solar Activity Future Estimation (MSAFE) Model

NASA Technical Reports Server (NTRS)

Suggs, Ron

2017-01-01

The MSAFE model provides forecasts for the solar indices SSN, F10.7, and Ap. These solar indices are used as inputs to space environment models used in orbital spacecraft operations and space mission analysis. Forecasts from the MSAFE model are provided on the MSFC Natural Environments Branch's solar web page and are updated as new monthly observations become available. The MSAFE prediction routine employs a statistical technique that calculates deviations of past solar cycles from the mean cycle and performs a regression analysis to calculate the deviation from the mean cycle of the solar index at the next future time interval. The forecasts are initiated for a given cycle after about 8 to 9 monthly observations from the start of the cycle are collected. A forecast made at the beginning of cycle 24 using the MSAFE program captured the cycle fairly well with some difficulty in discerning the double peak that occurred at solar cycle maximum.

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. Multiradionuclide evidence for the solar origin of the cosmic-ray events of AD 774/5 and 993/4. Nature Communications 6: 8, doi:10.1038/ncomms9611 (2015).

The Solar Cycle and, How Do We Know What We Know?

NASA Technical Reports Server (NTRS)

Adams, Mitzi

2013-01-01

Through the use of observations, mathematics, mathematical tools (such as graphs), inference, testing, and prediction we have gathered evidence that there are sunspots, a solar cycle, and have begun to understand more about our star, the Sun. We are making progress in understanding the cause of the solar cycle. We expect solar cycle 24 to peak soon. Cycle 24 will be the smallest cycle in 100 years.

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.

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.

From space weather toward space climate time scales: Substorm analysis from 1993 to 2008

NASA Astrophysics Data System (ADS)

Tanskanen, E. I.; Pulkkinen, T. I.; Viljanen, A.; Mursula, K.; Partamies, N.; Slavin, J. A.

2011-05-01

Magnetic activity in the Northern Hemisphere auroral region was examined during solar cycles 22 and 23 (1993-2008). Substorms were identified from ground-based magnetic field measurements by an automated search engine. On average, 550 substorms were observed per year, which gives in total about 9000 substorms. The interannual, seasonal and solar cycle-to-cycle variations of the substorm number (Rss), substorm duration (Tss), and peak amplitude (Ass) were examined. The declining phases of both solar cycles 22 and 23 were more active than the other solar cycle phases due to the enhanced solar wind speed. The spring substorms during the declining solar cycle phase (∣Ass,decl∣ = 500 nT) were 25% larger than the spring substorms during the ascending solar cycle years (∣Ass,acs∣ = 400 nT). The following seasonal variation was found: the most intense substorms occurred during spring and fall, the largest substorm frequency in the Northern Hemisphere winter, and the longest-duration substorms in summer. Furthermore, we found a winter-summer asymmetry in the substorm number and duration, which is speculated to be due to the variations in the ionospheric conductivity. The solar cycle-to-cycle variation was found in the yearly substorm number and peak amplitude. The decline from the peak substorm activity in 1994 and 2003 to the following minima took 3 years during solar cycle 22, while it took 6 years during solar cycle 23.

The May 1967 great storm and radio disruption event: Extreme space weather and extraordinary responses

NASA Astrophysics Data System (ADS)

Knipp, D. J.; Ramsay, A. C.; Beard, E. D.; Boright, A. L.; Cade, W. B.; Hewins, I. M.; McFadden, R. H.; Denig, W. F.; Kilcommons, L. M.; Shea, M. A.; Smart, D. F.

2016-09-01

Although listed as one of the most significant events of the last 80 years, the space weather storm of late May 1967 has been of mostly fading academic interest. The storm made its initial mark with a colossal solar radio burst causing radio interference at frequencies between 0.01 and 9.0 GHz and near-simultaneous disruptions of dayside radio communication by intense fluxes of ionizing solar X-rays. Aspects of military control and communication were immediately challenged. Within hours a solar energetic particle event disrupted high-frequency communication in the polar cap. Subsequently, record-setting geomagnetic and ionospheric storms compounded the disruptions. We explain how the May 1967 storm was nearly one with ultimate societal impact, were it not for the nascent efforts of the United States Air Force in expanding its terrestrial weather monitoring-analysis-warning-prediction efforts into the realm of space weather forecasting. An important and long-lasting outcome of this storm was more formal Department of Defense-support for current-day space weather forecasting. This story develops during the rapid rise of solar cycle 20 and the intense Cold War in the latter half of the twentieth century. We detail the events of late May 1967 in the intersecting categories of solar-terrestrial interactions and the political-military backdrop of the Cold War. This was one of the "Great Storms" of the twentieth century, despite the apparent lack of large geomagnetically induced currents. Radio disruptions like those discussed here warrant the attention of today's radio-reliant, cellular-phone and satellite-navigation enabled world.

The May 1967 Great Storm and Radio Disruption Event: The Impacts We Didn't Know About

NASA Astrophysics Data System (ADS)

Knipp, D.

2016-12-01

Although listed as one of the most significant events of the last 80 years, the space weather storm of late May 1967 has been of mostly fading academic interest. The storm made its initial mark with a colossal solar radio burst causing radio interference at frequencies between 0.01-9.0 GHz and near-simultaneous disruptions of dayside radio communication by intense fluxes of ionizing solar X-rays. Aspects of military control and communication were immediately challenged. Within hours a solar energetic particle event disrupted high frequency communication in the polar cap. Subsequently record-setting geomagnetic and ionospheric storms compounded the disruptions. We explain how the May 1967 storm was nearly one with ultimate societal impact, were it not for the nascent efforts of the United States Air Force in expanding its terrestrial weather monitoring-analysis-warning-prediction efforts into the realm of space weather forecasting. This event is also one with severe impacts on thermospheric temperature and satellite drag. This story develops during the rapid rise of solar cycle 20 and the intense Cold War in the latter half of the 20th Century. We detail the events of late May 1967 in the intersecting categories of solar-terrestrial interactions and the political-military backdrop of the Cold War. This was one of the "Great Storms" of the 20th century, despite the lack of large geomagnetically-induced currents. Radio disruptions like those discussed here warrant the attention of today's radio-reliant, cellular-phone and satellite-navigation enabled world.

Deciphering The Fall And Rise Of The Dead Sea In Relation To Solar Forcing

NASA Astrophysics Data System (ADS)

Yousef, Shahinaz M.

2005-03-01

Solar Forcing on closed seas and Lakes is space time dependent. The Cipher of the Dead Sea level variation since 1200 BC is solved in the context of millenium and Wolf-Gleissberg solar cycles time scales. It is found that the pattern of Dead Sea level variation follows the pattern of major millenium solar cycles. The 70 m rise of Dead Sea around 1AD is due to the forcing of the maximum millenium major solar cycle. Although the pattern of the Dead Sea level variation is almost identical to major solar cycles pattern between 1100 and 1980 AD, there is a dating problem of the Dead Sea time series around 1100-1300 AD that time. A discrepancy that should be corrected for the solar and Dead Sea series to fit. Detailed level variations of the Dead Sea level for the past 200 years are solved in terms of the 80-120 years solar Wolf-Gliessberg magnetic cycles. Solar induced climate changes do happen at the turning points of those cycles. Those end-start and maximum turning points are coincident with the change in the solar rotation rate due to the presence of weak solar cycles. Such weak cycles occur in series of few cycles between the end and start of those Wolf-Gleissberg cycles. Another one or two weak r solar cycle occur following the maximum of those Wolf-Gleissberg cycles. Weak cycles induce drop in the energy budget emitted from the sun and reaching the Earth thus causing solar induced climate change. An 8 meter sudden rise of Dead Sea occur prior 1900 AD due to positive solar forcing of the second cycle of the weak cycles series on the Dead Sea. The same second weak cycle induced negative solar forcing on Lake Chad. The first weak solar cycle forced Lake Victoria to rise abruptly in 1878. The maximum turning point of the solar Wolf-Gleissberg cycle induced negative forcing on both the Aral Sea and the Dead Sea causing their shrinkage to an alarming reduced area ever since. On the other hand, few years delayed positive forcing caused Lake Chad and the Equatorial African lakes to rise abruptly by several meters. Since the present solar cycle number 23 is the first weak cycle of a series, and since it caused 1.6 m sharp rise in Lake Victoria in 1997, then there is a high probability that the Dead Sea will rise by the beginning of the second weak cycle in few years time. And since both the Aral Sea and the Dead Sea are very much in coherence since the late 1950s, then it is rather likely that the Aral Sea will rise with God's wish in the near future. However it is also demanded that Israel should allow more water of the Jordan River to feed the Dead Sea before its real death. Plans for joining the Dead sea to the Red and or to the Mediterranean Seas should be cancelled owing the damaging harm it will cause the Dead Sea as a perfect indicator of solar induced climate change on one hand. On the other hand, the Dead Sea time series always show abrupt changes that can be as high as 70 m; if we add to this a planned artificial rise of the Dead Sea to its level of the thirties, then a damaging flooding effect will ruin the establishments and environment greatly.

Net Metering Policy Development and Distributed Solar Generation in Minnesota: Overview of Trends in Nationwide Policy Development and Implications of Increasing the Eligible System Size Cap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doris, E.; Busche, S.; Hockett, S.

2009-12-01

The goal of the Minnesota net metering policy is to give the maximum possible encouragement to distributed generation assets, especially solar electric systems (MN 2008). However, according to a published set of best practices (NNEC 2008) that prioritize the maximum development of solar markets within states, the Minnesota policy does not incorporate many of the important best practices that may help other states transform their solar energy markets and increase the amount of grid-connected distributed solar generation assets. Reasons cited include the low system size limit of 40kW (the best practices document recommends a 2 MW limit) and a lackmore » of language protecting generators from additional utility fees. This study was conducted to compare Minnesota's policies to national best practices. It provides an overview of the current Minnesota policy in the context of these best practices and other jurisdictions' net metering policies, as well as a qualitative assessment of the impacts of raising the system size cap within the policy based on the experiences of other states.« less

The Role of Ionospheric Conductivity in the Response of the Magnetosphere and Ionosphere to Changes in the Earth's Magnetic Field

NASA Astrophysics Data System (ADS)

Cnossen, I.; Wiltberger, M. J.; Richmond, A. D.; Ouellette, J.

2014-12-01

The strength and orientation of the Earth's magnetic field play an important role in the magnetosphere-ionosphere-thermosphere system. This is demonstrated in a set of idealized experiments with the Coupled Magnetosphere-Ionosphere-Thermosphere model using a dipolar magnetic field. A decrease of the dipole moment (M) causes an increase in ionospheric conductance. This increase in conductance results in enhanced field-aligned currents (FACs), which change the shape of the magnetosphere, and causes a deviation from theoretical scaling relations of the stand-off distance, the size of the polar cap, and the cross-polar cap potential with M. The orientation of the Earth's magnetic field determines how the angle μ between the geomagnetic dipole axis and the geocentric solar magnetospheric (GSM) z-axis varies with season and universal time (UT). The angle μ can affect solar wind-magnetosphere-ionosphere coupling in two distinct ways: via variations in ionospheric conductivity over the polar caps or via a change in the coupling efficiency between the solar wind and magnetosphere as a result of changes in geometry. Simulations in which the ionospheric conductivity was either kept fixed or allowed to vary realistically demonstrated that variations in ionospheric conductance are responsible for ~10-30% of the variations in the cross-polar cap potential associated with variations in μ for southward interplanetary magnetic field (IMF). The remainder was mostly due to variations in the magnetic reconnection rate, which were associated with variations in the length of the section of the separator line along which relatively strong reconnection occurs.

Will Solar Cycles 25 and 26 Be Weaker than Cycle 24?

NASA Astrophysics Data System (ADS)

Javaraiah, J.

2017-11-01

The study of variations in solar activity is important for understanding the underlying mechanism of solar activity and for predicting the level of activity in view of the activity impact on space weather and global climate. Here we have used the amplitudes (the peak values of the 13-month smoothed international sunspot number) of Solar Cycles 1 - 24 to predict the relative amplitudes of the solar cycles during the rising phase of the upcoming Gleissberg cycle. We fitted a cosine function to the amplitudes and times of the solar cycles after subtracting a linear fit of the amplitudes. The best cosine fit shows overall properties (periods, maxima, minima, etc.) of Gleissberg cycles, but with large uncertainties. We obtain a pattern of the rising phase of the upcoming Gleissberg cycle, but there is considerable ambiguity. Using the epochs of violations of the Gnevyshev-Ohl rule (G-O rule) and the `tentative inverse G-O rule' of solar cycles during the period 1610 - 2015, and also using the epochs where the orbital angular momentum of the Sun is steeply decreased during the period 1600 - 2099, we infer that Solar Cycle 25 will be weaker than Cycle 24. Cycles 25 and 26 will have almost same strength, and their epochs are at the minimum between the current and upcoming Gleissberg cycles. In addition, Cycle 27 is expected to be stronger than Cycle 26 and weaker than Cycle 28, and Cycle 29 is expected to be stronger than both Cycles 28 and 30. The maximum of Cycle 29 is expected to represent the next Gleissberg maximum. Our analysis also suggests a much lower value (30 - 40) for the maximum amplitude of the upcoming Cycle 25.

The effect of different thickness alumina capping layers on the final morphology of dewet thin Ni films

NASA Astrophysics Data System (ADS)

White, Benjamin C.; Behbahanian, Amir; Stoker, T. McKay; Fowlkes, Jason D.; Hartnett, Chris; Rack, Phillip D.; Roberts, Nicholas A.

2018-03-01

Nanoparticles on a substrate have numerous applications in nanotechnology, from enhancements to solar cell efficiency to improvements in carbon nanotube growth. Producing nanoparticles in a cost effective fashion with control over size and spacing is desired, but difficult to do. This work presents a scalable method for altering the radius and pitch distributions of nickel nanoparticles. The introduction of alumina capping layers to thin nickel films during a pulsed laser-induced dewetting process has yielded reductions in the mean and standard deviation of radii and pitch for dewet nanoparticles with no noticeable difference in final morphology with increased capping layer thickness. The differences in carbon nanotube mats grown, on the uncapped sample and one of the capped samples, is also presented here, with a more dense mat being present for the capped case.

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 65 +/- 20 in smoothed sunspot number, a below-average amplitude for Solar Cycle 24, with maximum at 2014.5+/-0.5, we conclude that Solar Cycle 24 will be no stronger than average and could be much weaker than average.

Observations and statistical simulations of a proposed solar cycle/QBO/weather relationship

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baldwin, M.P.; Dunkerton, T.J.

1989-08-01

The 10.7 cm solar flux is observed to be highly correlated with north pole stratospheric temperatures when partitioned according to the phase of the equatorial stratospheric winds (the quasi-biennial oscillation, or QBO). The authors supplement observations with calculations showing that temperatures over most of the northern hemisphere are highly correlated or anticorrelated with north pole temperatures. The observed spatial pattern of solar cycle correlations at high latitudes is shown to be not unique to the solar cycle. The authors present results, similar to the observed solar cycle correlations, with simulated harmonics of various periods replacing the solar cycle. These calculationsmore » demonstrate the correlations at least as high as those for the solar cycle results may be obtained using simulated harmonics.« less

Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

NASA Astrophysics Data System (ADS)

Xin, Zheng; Ling, Zhi Peng; Nandakumar, Naomi; Kaur, Gurleen; Ke, Cangming; Liao, Baochen; Aberle, Armin G.; Stangl, Rolf

2017-08-01

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density D it(E) and the total interface charge Q tot. Furthermore, the bonding configuration variation of the AlO x films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlO x tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlO x layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

Dynamo theory prediction of solar activity

NASA Technical Reports Server (NTRS)

Schatten, Kenneth H.

1988-01-01

The dynamo theory technique to predict decadal time scale solar activity variations is introduced. The technique was developed following puzzling correlations involved with geomagnetic precursors of solar activity. Based upon this, a dynamo theory method was developed to predict solar activity. The method was used successfully in solar cycle 21 by Schatten, Scherrer, Svalgaard, and Wilcox, after testing with 8 prior solar cycles. Schatten and Sofia used the technique to predict an exceptionally large cycle, peaking early (in 1990) with a sunspot value near 170, likely the second largest on record. Sunspot numbers are increasing, suggesting that: (1) a large cycle is developing, and (2) that the cycle may even surpass the largest cycle (19). A Sporer Butterfly method shows that the cycle can now be expected to peak in the latter half of 1989, consistent with an amplitude comparable to the value predicted near the last solar minimum.

Interspace modification of titania-nanorod arrays for efficient mesoscopic perovskite solar cells

NASA Astrophysics Data System (ADS)

Chen, Peng; Jin, Zhixin; Wang, Yinglin; Wang, Meiqi; Chen, Shixin; Zhang, Yang; Wang, Lingling; Zhang, Xintong; Liu, Yichun

2017-04-01

Morphology of electron transport layers (ETLs) has an important influence on the device architecture and electronic processes of mesostructured solar cells. In this work, we thoroughly investigated the effect of the interspace of TiO2 nanorod (NR) arrays on the photovoltaic performance of the perovskite solar cells (PSCs). Along with the interspace in TiO2-NR arrays increasing, the thickness as well as the crystal size of perovskite capping layer are reduced accordingly, and the filling of perovskite in the channel becomes incomplete. Electrochemical impedance spectroscopy measurements reveal that this variation of perovskite absorber layer, induced by interspace of TiO2 NR arrays, causes the change of charge recombination process at the TiO2/perovskite interface, suggesting that a balance between capping layer and the perovskite filling is critical to obtain high charge collection efficiency of PSCs. A power conversion efficiency of 10.3% could be achieved through careful optimization of interspace in TiO2-NR arrays. Our research will shed light on the morphology control of ETLs with 1D structure for heterojunction solar cells fabricated by solution-deposited method.

Response of the equatorial and polar magnetosphere to the very tenuous solar wind on May 11, 1999

NASA Astrophysics Data System (ADS)

Farrugia, C. J.; Singer, H. J.; Evans, D.; Berdichevsky, D.; Scudder, J. D.; Ogilvie, K. W.; Fitzenreiter, R. J.; Russell, C. T.

2000-12-01

We examine effects in the equatorial and polar magnetosphere during 9-13 May, 1999. Earth's field at geostationary orbit became closely dipolar for ˜16 hours when solar wind densities nsw were <1 cm-3. Electron precipitation in the northern polar cap intensified as nsw decreased, with significant fluxes up to ˜15 keV energy on May 11. The simultaneous precipitation void in the southern polar cap implies a very pronounced north-south asymmetry, also reflected in the hemispherical power deposition. With an intense and collimated strahl, these observations support the ideas of Fairfield and Scudder [1985] on the preferential entry of the strahl into the northern hemisphere under the observed IMF away sector as a source of the north-south precipitation asymmetry. The polar rain north-south asymmetry argues against an ejecta source for the solar wind drop-out. The temporal profiles of solar wind parameters were very asymmetric with respect to the time of minimum nsw, and strong compressions and substorm activity prevailed as nsw recovered.

Modeling polar cap F-region patches using time varying convection

NASA Technical Reports Server (NTRS)

Sojka, J. J.; Bowline, M. D.; Schunk, R. W.; Decker, D. T.; Valladares, C. E.; Sheehan, R.; Anderson, D. N.; Heelis, R. A.

1993-01-01

Creation of polar cap F-region patches are simulated for the first time using two independent physical models of the high latitude ionosphere. The patch formation is achieved by temporally varying the magnetospheric electric field (ionospheric convection) input to the models. The imposed convection variations are comparable to changes in the convection that result from changes in the B(y) IMF component for southward IMF. Solar maximum-winter simulations show that simple changes in the convection pattern lead to significant changes in the polar cap plasma structuring. Specifically, in winter, as enhanced dayside plasma convects into the polar cap to form the classic tongue-of-ionization the convection changes produce density structures that are indistinguishable from the observed patches.

78 FR 45983 - Acceptability of Corrective Action Programs for Fuel Cycle Facilities

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-30

... Programs for Fuel Cycle Facilities AGENCY: Nuclear Regulatory Commission. ACTION: Draft NUREG; withdrawal... withdrawing draft NUREG-2154, ``Acceptability of Corrective Action Programs for Fuel Cycle Facilities,'' based... determine whether a submittal for a Corrective Action Program (CAP), voluntarily submitted by fuel cycle...

Evolution of Our Understanding of the Solar Dynamo During Solar Cycle 24

NASA Astrophysics Data System (ADS)

Munoz-Jaramillo, A.

2017-12-01

Solar cycle 24 has been an exciting cycle for our understanding of the solar dynamo: 1. It was the first cycle for which dynamo based predictions were ever used teaching us valuable lessons. 2. It has given us the opportunity to observe a deep minimum and a weak cycle with a high level of of observational detail . 3. It is full of breaktrhoughs in anelastic MHD dynamo simulations (regular cycles, buoyant flux-tubes, mounder-like events). 4. It has seen the creation of bridges between the kinematic flux-transport and anelastic MHD approaches. 5. It has ushered a new generation of realistic surface flux-transport simulations 6. We have achieved significant observational progress in our understanding of solar cycle propagation. The objective of this talk is to highlight some of the most important results, giving special emphasis on what they have taught us about solar cycle predictability.

Structural properties of perovskite films on zinc oxide nanoparticles-reduced graphene oxide (ZnO-NPs/rGO) prepared by electrophoretic deposition technique

NASA Astrophysics Data System (ADS)

Bahtiar, Ayi; Nurazizah, Euis Siti; Latiffah, Efa; Risdiana, Furukawa, Yukio

2018-02-01

Perovskite solar cells highly believed as next generation solar cells to replace currently available inorganic silicon solar cells due to their high power conversion efficiency and easy processing to thin films using solution processing techniques. Performance and stability, however still need to be improved for mass production and widely used for public electricity generation. Perovskite solar cells are commonly deposited on Titanium Dioxide (TiO2) film as an effective electron transport layer (ETL). We used Zinc Oxide nanoparticles (ZnO-NPs) as ETL in perovskite solar cells due to the low temperature required for crystallization and can be formed into different shapes of nanostructures. However, perovskite film can easily degrade into insulating lead iodide due to deprotonation of the methylammoniumcation at the surface of ZnO-NPs, in particular when it stored in ambient air with high relative humidity. The degradation of perovskite layer is therefore needed to be overcome. Here, we capped ZnO-NPs with reduced graphene oxide (rGO) to overcome the degradation of perovskite film where ZnO-NPs is synthesized by sol-gel method. The average nanoparticle size of ZnO is 15 nm. ZnO-NPs and ZnO-NPs-rGO films are prepared using electrophoretic deposition technique, which can produce large area with good homogeneity and high reproducibility. The stability of perovskite layer can significantly be improved by capping ZnO with rGO, which is indicated by absence of color change of perovskite after storage for 5 (five) days in ambient air with relative humidity above 95%. Moreover, the X-Ray Diffaction peaks of perovskite film are more preserved when deposited on ZnO/rGO film than using only ZnO film. We strongly believe, by capping ZnO film with rGO, both the performance and stability of perovskite solar cells can be improved significantly.

PRMT5 is essential for the eIF4E-mediated 5′-cap dependent translation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Ji-Hong; Lee, Yoon-Mi; Lee, Gibok

2014-10-03

Highlights: • PRMT5 participates in syntheses of HIF-1α, c-Myc and cyclin D1 proteins. • PRMT5 promotes the 5′-cap dependent translation. • PRMT5 is required for eIF4E binding to mRNA 5′-cap. • PRMT5 is essential for eIF4E-dependent cell proliferation. - Abstract: It is becoming clear that PRMT5 plays essential roles in cell cycle progression, survival, and responses to external stresses. However, the precise mechanisms underlying such roles of PRMT5 have not been clearly understood. Previously, we have demonstrated that PRMT5 participates in cellular adaptation to hypoxia by ensuring 5′-cap dependent translation of HIF-1α. Given that c-Myc and cyclin D1 expressions aremore » also tightly regulated in 5′-cap dependent manner, we here tested the possibility that PRMT5 promotes cell proliferation by increasing de novo syntheses of the oncoproteins. c-Myc and cyclin D1 were found to be noticeably downregulated by PRMT5 knock-down. A RNA immunoprecipitation analysis, which can identify RNA–protein interactions, showed that PRMT5 is required for the interaction among eIF4E and 5′-UTRs of HIF-1α, c-Myc and cyclin D1 mRNAs. In addition, PRMT5 knock-down inhibited cell proliferation by inducing cell cycle arrest at the G1 phase. More importantly, ectopic expression of eIF4E significantly rescued the cell cycle progression and cell proliferation even in PRMT5-deficeint condition. Based on these results, we propose that PRMT5 determines cell fate by regulating 5′-cap dependent translation of proteins essential for proliferation and survival.« less

The inhibitory effects of capillarisin on cell proliferation and invasion of prostate carcinoma cells.

PubMed

Tsui, Ke-Hung; Chang, Ying-Ling; Yang, Pei-Shan; Hou, Chen-Pang; Lin, Yu-Hsiang; Lin, Bing-Wei; Feng, Tsui-Hsia; Juang, Horng-Heng

2018-04-01

Capillarisin (Cap), an active component of Artemisia capillaris root extracts, is characterized by its anti-inflammatory, anti-oxidant and anti-cancer properties. Nevertheless, the functions of Cap in prostate cancer have not been fully explored. We evaluated the potential actions of Cap on the cell proliferation, migration and invasion of prostate carcinoma cells. Cell proliferation and cell cycle distribution were measured by water-soluble tetrazolium-1 and flow cytometry assays. The expression of cyclins, p21, p27, survivin, matrix metallopeptidase (MMP2 and MMP9) were assessed by immunoblotting assays. Effects of Cap on invasion and migration were determined by wound closure and matrigel transmigration assays. The constitutive and interlukin-6 (IL-6)-inducible STAT3 activation of prostate carcinoma cells were determined by immunoblotting and reporter assays. Capillarisin inhibited androgen-independent DU145 and androgen-dependent LNCaP cell growth through the induction of cell cycle arrest at the G0/G1 phase by upregulating p21 and p27 while downregulating expression of cyclin D1, cyclin A and cyclin B. Cap decreased protein expression of survivin, MMP-2, and MMP-9 and therefore blocked the migration and invasion of DU145 cells. Cap suppressed constitutive and IL-6-inducible STAT3 activation in DU145 and LNCaP cells. Our data indicate that Cap blocked cell growth by modulation of p21, p27 and cyclins. The inhibitory effects of Cap on survivin, MMP-2, MMP-9 and STAT3 activation may account for the suppression of invasion in prostate carcinoma cells. Our data suggest that Cap might be a therapeutic agent in treating advanced prostate cancer with constitutive STAT3 or IL-6-inducible STAT3 activation. © 2017 John Wiley & Sons Ltd.

An intercomparison of the thermal offset for different pyranometers

NASA Astrophysics Data System (ADS)

Sanchez, G.; Cancillo, M. L.; Serrano, A.

2016-07-01

An unprecedented intensive intercomparison campaign focused on the experimental measurement of the thermal offset of pyranometers has been conducted at Badajoz (Spain) with the participation of three main manufacturers. The purpose of this study is to compare the thermal offset of six commercially available pyranometers, being some of them widely used and others recently commercialized. In this campaign, the capping methodology has been used to experimentally measure the daytime thermal offset of the pyranometers. Thus, a short but intense campaign has been conducted in two selected summer days under clear-sky conditions, covering a large range of solar zenith angle, irradiance, and temperature. Along the campaign, a total of 305 capping events have been performed, 61 for each pyranometer. The daytime thermal offset obtained for different pyranometers ranges between 0 and -16.8 W/m2 depending on the environmental conditions, being sometimes notably higher than values estimated indoors by manufacturers. The thermal offset absolute value of all instruments shows a diurnal cycle, increasing from sunrise to central hours of the day and decreasing from midafternoon to sunset. The analysis demonstrates that thermal offset is notably higher and more variable during daytime than during nighttime, requiring specific daytime measurements. Main results emphasize the key role played by wind speed in modulating the thermal offset.

The Boeing Delta II rocket with Mars Polar Lander aboard lifts off at Pad 17B, CCAS

NASA Technical Reports Server (NTRS)

1999-01-01

Amid clouds of exhaust, a Boeing Delta II expendable launch vehicle with NASA's Mars Polar Lander clears Launch Complex 17B, Cape Canaveral Air Station, after launch at 3:21:10 p.m. EST. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

The Boeing Delta II rocket with Mars Polar Lander aboard lifts off at Pad 17B, CCAS

NASA Technical Reports Server (NTRS)

1999-01-01

Silhouetted against the gray sky, a Boeing Delta II expendable launch vehicle with NASA's Mars Polar Lander lifts off from Launch Complex 17B, Cape Canaveral Air Station, at 3:21:10 p.m. EST. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

The Boeing Delta II rocket with Mars Polar Lander aboard lifts off at Pad 17B, CCAS

NASA Technical Reports Server (NTRS)

1999-01-01

Amid clouds of exhaust and into a gray-clouded sky , a Boeing Delta II expendable launch vehicle lifts off with NASA's Mars Polar Lander at 3:21:10 p.m. EST from Launch Complex 17B, Cape Canaveral Air Station. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern- most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98 missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

The Boeing Delta II rocket with Mars Polar Lander aboard lifts off at Pad 17B, CCAS

NASA Technical Reports Server (NTRS)

1999-01-01

A Boeing Delta II expendable launch vehicle lifts off with NASA's Mars Polar Lander into a cloud-covered sky at 3:21:10 p.m. EST from Launch Complex 17B, Cape Canaveral Air Station. The lander is a solar-powered spacecraft designed to touch down on the Martian surface near the northern-most boundary of the south polar cap, which consists of carbon dioxide ice. The lander will study the polar water cycle, frosts, water vapor, condensates and dust in the Martian atmosphere. It is equipped with a robotic arm to dig beneath the layered terrain at the polar cap. In addition, Deep Space 2 microprobes, developed by NASA's New Millennium Program, are installed on the lander's cruise stage. After crashing into the planet's surface, they will conduct two days of soil and water experiments up to 1 meter (3 feet) below the Martian surface, testing new technologies for future planetary descent probes. The lander is the second spacecraft to be launched in a pair of Mars Surveyor '98missions. The first is the Mars Climate Orbiter, which was launched aboard a Delta II rocket from Launch Complex 17A on Dec. 11, 1998.

Sunspot Time Series: Passive and Active Intervals

NASA Astrophysics Data System (ADS)

Zięba, S.; Nieckarz, Z.

2014-07-01

Solar activity slowly and irregularly decreases from the first spotless day (FSD) in the declining phase of the old sunspot cycle and systematically, but also in an irregular way, increases to the new cycle maximum after the last spotless day (LSD). The time interval between the first and the last spotless day can be called the passive interval (PI), while the time interval from the last spotless day to the first one after the new cycle maximum is the related active interval (AI). Minima of solar cycles are inside PIs, while maxima are inside AIs. In this article, we study the properties of passive and active intervals to determine the relation between them. We have found that some properties of PIs, and related AIs, differ significantly between two group of solar cycles; this has allowed us to classify Cycles 8 - 15 as passive cycles, and Cycles 17 - 23 as active ones. We conclude that the solar activity in the PI declining phase (a descending phase of the previous cycle) determines the strength of the approaching maximum in the case of active cycles, while the activity of the PI rising phase (a phase of the ongoing cycle early growth) determines the strength of passive cycles. This can have implications for solar dynamo models. Our approach indicates the important role of solar activity during the declining and the rising phases of the solar-cycle minimum.

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

NASA Astrophysics Data System (ADS)

Gholibeigian, Kazem; Gholibeigian, Hassan

2016-04-01

On March 13, 1989 the entire province of Quebec Blackout by solar storm during solar cycle 22. The solar storm of 1859, also known as the Carrington event, was a powerful geomagnetic solar storm during solar cycle 10. The solar storm of 2012 during solar cycle 24 was of similar magnitude, but it passed Earth's orbit without striking the plane. All of these solar storms occurred in the peak of 11 yearly solar cycles. In this way, the White House in its project which is focusing on hazards from solar system, in a new strategy and action plan to increase protection from damaging solar emissions, should focus on coupling of the matched Gravity and Electromagnetic Fields)GEFs) of the Sun with Jupiter and its moons together. On the other hand, in solar system, the Jupiter's gravity has largest effect to the Sun's core and its dislocation, because the gravity force between the Jupiter and the Sun is 11.834 times, In addition overlapping of the solar cycles with the Jupiter's orbit period is 11.856 years. These observable factors lead us to the effect of the Jupiter and Sun gravity fields coupling as the main cause of the approximately 11 years duration for solar cycles. Its peak in each cycle is when the Jupiter is in nearest portion to the Sun in its orbit. In this way, the other planets in their coupling with Sun help to the variations and strengthening solar cycles. [Gholibeigian, 7/24/2015http://adsabs.harvard.edu/abs/2014EGU]. In other words, the both matched GEFs are generating by the large scale forced convection system inside the stars and planets [Gholibeigian et. al, AGU Fall Meeting 2015]. These two fields are couple and strengthening each other. The Jupiter with its 67 moons generate the largest coupled and matched GEFs in its core and consequently strongest effect on the Sun's core. Generation and coupling of the Jupiter's GEFs with its moons like Europa, Io and Ganymede make this planet of thousands of times brighter and many times bigger than Earth as the strongest variable GEFs in solar system after the Sun. For example, Ganymede is the largest moon of Jupiter and in the Solar System. Completing an orbit in roughly seven days. It means that it generates 52 GEFs oscillations (loading, unloading) per year in solar cycle while it is rotating around the Jupiter. New observations of the planet's extreme ultraviolet emissions show that bright explosions of Jupiter's aurora by the planet-moon interaction, not by solar activity [Tomoki Kimura, JAEA]. Coupling of Jupiter's GEFs and its moons with the Sun generate very strong GEFs and approximately 11 yearly solar cycles. The peaks of each cycle is when the Jupiter passes from the nearest portion of its orbit to the Sun. which some of its peaks generate gigantic solar storms and hazards to the Earth. The Earth passes from between of Sun and Jupiter eleven times in each solar cycle and may be under shooting of storms from the both side specially during 2-3 years in cycle's peak.

ESTIMATE OF SOLAR MAXIMUM USING THE 1-8 Å GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITES X-RAY MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winter, L. M.; Balasubramaniam, K. S., E-mail: lwinter@aer.com

We present an alternate method of determining the progression of the solar cycle through an analysis of the solar X-ray background. Our results are based on the NOAA Geostationary Operational Environmental Satellites (GOES) X-ray data in the 1-8 Å band from 1986 to the present, covering solar cycles 22, 23, and 24. The X-ray background level tracks the progression of the solar cycle through its maximum and minimum. Using the X-ray data, we can therefore make estimates of the solar cycle progression and the date of solar maximum. Based upon our analysis, we conclude that the Sun reached its hemisphere-averagedmore » maximum in solar cycle 24 in late 2013. This is within six months of the NOAA prediction of a maximum in spring 2013.« less

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.

A study of the asymmetrical distribution of solar activity features on solar and plasma parameters (1967-2016)

NASA Astrophysics Data System (ADS)

El-Borie, M. A.; El-Taher, A. M.; Aly, N. E.; Bishara, A. A.

2018-04-01

The impact of asymmetrical distribution of hemispheric sunspot areas (SSAs) on the interplanetary magnetic field, plasma, and solar parameters from 1967 to 2016 has been studied. The N-S asymmetry of solar-plasma activities based on SSAs has a northern dominance during solar cycles 20 and 24. However, it has a tendency to shift to the southern hemisphere in cycles 21, 22, and 23. The solar cycle 23 showed that the sorted southern SSAs days predominated over the northern days by ˜17%. Through the solar cycles 21-24, the SSAs of the southern hemisphere were more active. In contrast, the northern SSAs predominate over the southern one by 9% throughout solar cycle 20. On the other hand, the average differences of field magnitude for the sorted northern and southern groups during solar cycles 20-24 are statistically insignificant. Clearly, twenty years showed that the solar plasma ion density from the sorted northern group was denser than that of southern group and a highest northern dominant peak occurred in 1971. In contrast, seventeen out of fifty years showed the reverse. In addition, there are fifteen clear asymmetries of solar wind speed (SWS), with SWS (N) > SWS (S), and during the years 1972, 2002, and 2008, the SWS from the sorted northern group was faster than that of southern activity group by 6.16 ± 0.65 km/s, 5.70 ± 0.86 km/s, and 5.76 ± 1.35 km/s, respectively. For the solar cycles 20-24, the grand-averages of P from the sorted solar northern and southern have nearly the same parameter values. The solar plasma was hotter for the sorted northern activity group than the southern ones for 17 years out of 50. Most significant northern prevalent asymmetries were found in 1972 (5.76 ± 0.66 × 103 K) and 1996 (4.7 ± 0.8 × 103 K), while two significant equivalent dominant southern asymmetries (˜3.8 ± 0.3 × 103 K) occurred in 1978 and 1993. The grand averages of sunspot numbers have symmetric activity for the two sorted northern and southern hemispheres through the solar cycles 20 and 21. The sunspots tend to be the southern dominance during the solar cycles 22 and 23, and it shifted during solar cycle 24 to symmetric distribution on both solar hemispheres.

The seasonal cycle of water on Mars

NASA Technical Reports Server (NTRS)

Jakosky, B. M.

1985-01-01

A review of the behavior of water in the Mars atmosphere and subsurface is appropriate now that data from the Mariner and Viking spacecraft have been analyzed and discussed for several years following completion of those missions. Observations and analyses pertinent to the seasonal cycle of water vapor in the atmosphere of Mars are reviewed, with attention toward transport of water and the seasonal exchange of water between the atmosphere and various non-atmospheric reservoirs. Possible seasonally-accessible sources and sinks for water include water ice on or within the seasonal and residual polar caps; surface or subsurface ice in the high-latitude regions of the planet; adsorbed or chemically-bound water within the near-surface regolith; or surface or subsurface liquid water. The stability of water within each of these reservoirs is discussed, as are the mechanisms for driving exchange of the water with the atmosphere and the timescales for exchange. Specific conclusions are reached about the distribution of water and the viability of each mechanism as a seasonal reservoir. Discussion is also included of the behavior of water on longer timescales, driven by the variations in solar forcing due to the quasi-periodic variations of the orbital obliquity. Finally, specific suggestions are made for future observations from spacecraft which would further define or constrain the seasonal cycle of water.

Project for Solar-Terrestrial Environment Prediction (PSTEP): Towards Predicting Next Solar Cycle

NASA Astrophysics Data System (ADS)

Imada, S.; Iijima, H.; Hotta, H.; Shiota, D.; Kanou, O.; Fujiyama, M.; Kusano, K.

2016-10-01

It is believed that the longer-term variations of the solar activity can 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 activity level of the next solar cycle is a key for the long-term space weather study. Although three-years prediction can be almost achieved, the prediction of next solar cycle is very limited, so far. We are developing a five-years prediction scheme by combining the Surface Flux Transport (SFT) model and the most accurate measurements of solar magnetic fields as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction),. We estimate the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters are 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. We also report the present status and the future perspective of our project.

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.

Helioseismology Observations of Solar Cycles and Dynamo Modeling

NASA Astrophysics Data System (ADS)

Kosovichev, A. G.; Guerrero, G.; Pipin, V.

2017-12-01

Helioseismology observations from the SOHO and SDO, obtained in 1996-2017, provide unique insight into the dynamics of the Sun's deep interior for two solar cycles. The data allow us to investigate variations of the solar interior structure and dynamics, and compare these variations with dynamo models and simulations. We use results of the local and global helioseismology data processing pipelines at the SDO Joint Science Operations Center (Stanford University) to study solar-cycle variations of the differential rotation, meridional circulation, large-scale flows and global asphericity. By comparing the helioseismology results with the evolution of surface magnetic fields we identify characteristic changes associated the initiation and development of Solar Cycles 23 and 24. For the physical interpretation of observed variations, the 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 solar dynamo mechanism, may explain the fundamental difference between the two solar cycles, and also give information about the next solar cycle.

Hydrothermal synthesis of alpha- and beta-HgS nanostructures

NASA Astrophysics Data System (ADS)

Galain, Isabel; María, Pérez Barthaburu; Ivana, Aguiar; Laura, Fornaro

2017-01-01

We synthesized HgS nanostructures by the hydrothermal method in order to use them as electron acceptors in hybrid organic-inorganic solar cells. We employed different mercury sources (HgO and Hg(CH3COO)2) and polyvinylpyrrolidone (PVP) or hexadecanethiol (HDT) as stabilizing/capping agent for controlling size, crystallinity, morphology and stability of the obtained nanostructures. We also used thiourea as sulfur source, and a temperature of 180 °C during 6 h. Synthesized nanostructures were characterized by powder X-Ray Diffraction, Diffuse Reflectance Infrared Fourier Transform and Transmission Electron Microscopy. When PVP acts as stabilizing agent, the mercury source has influence on the size -but not in morphology- of the beta-HgS obtained nansostructures. HDT has control over nanostructures' size and depending on the relation Hg:HDT, we obtained a mixture of alpha and beta HgS which can be advantageous in the application in solar cells, due their absorption in different spectral regions. The smallest nanostructures obtained have a mean diameter of 20 nm when using HDT as capping agent. Also, we deposited the aforementioned nanostructures onto flat glass substrates by the spin coating technique as a first approach of an active layer of a solar cell. The depositions were characterized by atomic force microscopy. We obtained smaller particle deposition and higher particle density -but a lower area coverage (5%) - in samples with HDT as capping agent. This work presents promising results on nanostructures for future application on hybrid solar cells. Further efforts will be focused on the deposition of organic-inorganic layers.

Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-Flaring Active Regions

NASA Astrophysics Data System (ADS)

Kilcik, A.; Yurchyshyn, V.; Donmez, B.; Obridko, V. N.; Ozguc, A.; Rozelot, J. P.

2018-04-01

We analyzed temporal and periodic variations of sunspot counts (SSCs) in flaring (C-, M-, or X-class flares), and non-flaring active regions (ARs) for nearly three solar cycles (1986 through 2016). Our main findings are as follows: i) temporal variations of monthly means of the daily total SSCs in flaring and non-flaring ARs behave differently during a solar cycle and the behavior varies from one cycle to another; during Solar Cycle 23 temporal SSC profiles of non-flaring ARs are wider than those of flaring ARs, while they are almost the same during Solar Cycle 22 and the current Cycle 24. The SSC profiles show a multi-peak structure and the second peak of flaring ARs dominates the current Cycle 24, while the difference between peaks is less pronounced during Solar Cycles 22 and 23. The first and second SSC peaks of non-flaring ARs have comparable magnitude in the current solar cycle, while the first peak is nearly absent in the case of the flaring ARs of the same cycle. ii) Periodic variations observed in the SSCs profiles of flaring and non-flaring ARs derived from the multi-taper method (MTM) spectrum and wavelet scalograms are quite different as well, and they vary from one solar cycle to another. The largest detected period in flaring ARs is 113± 1.6 days while we detected much longer periodicities (327± 13, 312 ± 11, and 256± 8 days) in the non-flaring AR profiles. No meaningful periodicities were detected in the MTM spectrum of flaring ARs exceeding 55± 0.7 days during Solar Cycles 22 and 24, while a 113± 1.3 days period was detected in flaring ARs of Solar Cycle 23. For the non-flaring ARs the largest detected period was only 31± 0.2 days for Cycle 22 and 72± 1.3 days for the current Cycle 24, while the largest measured period was 327± 13 days during Solar Cycle 23.

How active was solar cycle 22?

NASA Technical Reports Server (NTRS)

Hoegy, W. R.; Pesnell, W. D.; Woods, T. N.; Rottman, G. J.

1993-01-01

Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar cycle 22 was more active than solar cycle 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV flux over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV flux correlated very well with the SME measurement of L-alpha during the lifetime of SME and with the UARS SOLSTICE L-alpha from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar cycle 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar cycle 22. From 1989 to the start of 1992, the 10.7 cm flux exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and L-alpha during the cycle 22 peak is the total magnetic flux. The case for high activity during this peak is also supported by the presence of very high solar flare intensity.

Rechargeable dental adhesive with calcium phosphate nanoparticles for long-term ion release

PubMed Central

Zhang, Ling; Weir, Michael D.; Hack, Gary; Fouad, Ashraf F.; Xu, Hockin H. K.

2015-01-01

Objectives The tooth-resin bond is the weak link of restoration, with secondary caries as a main reason for failure. Calcium phosphate-containing resins are promising for remineralization; however, calcium (Ca) and phosphate (P) ion releases last only a couple of months. The objectives of this study were to develop the first rechargeable CaP bonding agent and investigate the key factors that determine CaP ion recharge and re-release. Methods Nanoparticles of amorphous calcium phosphate (NACP) were synthesized. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol-A glycidyl dimethacrylate (BisGMA) were used to synthesize three adhesives (denoted PE, PEH and PEHB). NACP were mixed into adhesive at 0–30% by mass. Dentin shear bond strengths were measured. Adhesive specimens were tested for Ca and P initial ion release. Then the ion-exhausted specimens were immersed in Ca and P solution to recharge the specimens, and the recharged specimens were then used to measure ion re-release for 7 days as one cycle. Then these specimens were again recharged and the re-release was measured for 7 days as the second cycle. Three recharge/re-release cycles were tested. Results PEHB had the highest dentin bond strength (p<0.05). Increasing NACP content from 0 to 30% did not affect dentin bond strength (p>0.1), but increased CaP release and re-release (p<0.05). PEHB-NACP had the greatest recharge/re-release, and PE-NACP had the least (p<0.05). Ion release remained high and did not decrease with increasing the number of recharge/re-release cycles (p>0.1). After the third cycle, specimens without further recharge had continuous CaP ion release for 2–3 weeks. Significance Rechargeable CaP bonding agents were developed for the first time to provide long-term Ca and P ions to promote remineralization and reduce caries. Incorporation of NACP into adhesive had no negative effect on dentin bond strength. Increasing NACP filler level increased the ion recharge and re-release capability. The new CaP recharge method and PMGDM-EBPAGMA-NACP composition may have wide application in adhesives, composites and cements, to combat caries and remineralize lesions. PMID:26144190

H2O grain size and the amount of dust in Mars' residual north polar cap

NASA Technical Reports Server (NTRS)

Kieffer, Hugh H.

1990-01-01

In Mars' north polar cap, the probable composition of material residual from the annual condensation cycle is a mixture of fine dust and H2O grains of comparable size and abundance. However, metamorphism of such material will gradually lower its albedo by increasing the size of the H2O grains only. If the cap is undergoing net annual sublimation (as inferred from water vapor observations), late summer observations should be of old ice with H2O grain sizes of 100 microns or more. Ice of this granularity containing 30 percent fine dust has a reflectivity similar to that of dust alone; the observed albedo and computed ice grain size imply dust concentrations of 1 part per 1000 or less. The brightness of the icy areas conflicts with what would be expected for a residual cap deposited by an annual cycle similar to that observed by Viking and aged for thousands of years. The residual cap surface cannot be 'old dirty' ice. It could be old, coarse, and clean; or it could be young, fine, and dirty. This brings into question both the source of the late summer water vapor and the formation rate of laminated terrain.

H2O grain size and the amount of dust in Mars' residual North polar cap

USGS Publications Warehouse

Kieffer, H.H.

1990-01-01

In Mars' north polar cap the probable composition of material residual from the annual condensation cycle is a mixture of fine dust and H2O grains of comparable size and abundance. However, metamorphism of such material will gradually lower its albedo by increasing the size of the H2O grains only. If the cap is undergoing net annual sublimation (as inferred from water vapor observations), late summer observations should be of old ice with H2O grain sizes of 100 ??m or more. Ice of this granularity containing 30% fine dust has a reflectivity similar to that of dust alone; the observed albedo and computed ice grain size imply dust concentrations of 1 part per 1000 or less. The brightness of the icy areas conflicts with what would be expected for a residual cap deposited by an annual cycle similar to that observed by Viking and aged for thousands of years. The residual cap surface cannot be "old dirty' ice. It could be old, coarse, and clean; or it could be young, fine, and dirty. This brings into question both the source of the late summer water vapor and the formation rate of laminated terrain. -Author

Understanding the Balance of Dayside and Nightside Reconnection Contributions to the Cross Polar Cap Potential During Solar Wind Disturbances

DTIC Science & Technology

2014-05-15

13. SUPPLEMENTARY NOTES 14. ABSTRACT This study focused on the investigation of how solar wind energy is deposited into the magnetosphere- ionosphere ...system during sudden enhancements of solar wind dynamic pressure (Psw), using the coupled OpenGGCM-CTIM 3D global magnetosphere – ionosphere ...CPCP), a proxy of ionospheric plasma convection strength, were quantified. The modeled CPCP increased after a Psw enhancement in all three cases, which

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.

Two-parameter model of total solar irradiance variation over the solar cycle

NASA Technical Reports Server (NTRS)

Pap, Judit M.; Willson, Richard C.; Donnelly, Richard F.

1991-01-01

Total solar irradiance measured by the SMM/ACRIM radiometer is modelled from the Photometric Sunspot Index and the Mg II core-to-wing ratio with multiple regression analysis. Considering that the formation of the Mg II line is very similar to that of the Ca II K line, the Mg II core-to-wing ratio, measured by the Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements, including faculae and the magnetic network. It is shown that the relationship between the variations in total solar irradiance and the above solar activity indices depends upon the phase of the solar cycle. Thus, a better fit between total irradiance and its model estimates can be achieved if the irradiance models are calculated for the declining portion and minimum of solar cycle 21, and the rising portion of solar cycle 22, respectively. There is an indication that during the rising portion of solar cycle 22, similar to the maximum time of solar cycle 21, the modelled total irradiance values underestimate the measured values. This suggests that there is an asymmetry in the long-term total irradiance variability.

The polar caps

NASA Astrophysics Data System (ADS)

Akasofu, S.-I.

1985-12-01

According to the most common definition, the 'polar cap' is the region bounded by the average or statistical auroral oval. Studies of the effects of the interplanetary magnetic field (IMF) on various upper atmospheric phenomena are reviewed. The Antarctic region and the Arctic region represent an area for such investigations. Particular attention is given in this paper to those observations in the highest latitude region which provide some information concerning corresponding changes of the internal structure of the magnetosphere. A definition and working definition of the polar cap are considered along with the IMF and magnetospheric models, the entry of solar energetic electrons, statistical studies regarding the aurora, individual events, polar cap arcs, the cusp aurora, auroral electron precipitation, convection, ionospheric currents and field-aligned currents, the ionosphere, the thermosphere, polar rain, polar wind, and hopping motions of heavy ions.

Solar Electric Propulsion

NASA Technical Reports Server (NTRS)

LaPointe, Michael

2006-01-01

The Solar Electric Propulsion (SEP) technology area is tasked to develop near and mid-term SEP technology to improve or enable science mission capture while minimizing risk and cost to the end user. The solar electric propulsion investments are primarily driven by SMD cost-capped mission needs. The technology needs are determined partially through systems analysis tasks including the recent "Re-focus Studies" and "Standard Architecture Study." These systems analysis tasks transitioned the technology development to address the near term propulsion needs suitable for cost-capped open solicited missions such as Discovery and New Frontiers Class missions. Major SEP activities include NASA's Evolutionary Xenon Thruster (NEXT), implementing a Standard Architecture for NSTAR and NEXT EP systems, and developing a long life High Voltage Hall Accelerator (HiVHAC). Lower level investments include advanced feed system development and xenon recovery testing. Future plans include completion of ongoing ISP development activities and evaluating potential use of commercial electric propulsion systems for SMD applications. Examples of enhanced mission capability and technology readiness dates shall be discussed.

Evaluation of long term solar activity effects on GPS derived TEC

NASA Astrophysics Data System (ADS)

Mansoori, Azad A.; Khan, Parvaiz A.; Ahmad, Rafi; Atulkar, Roshni; M, Aslam A.; Bhardwaj, Shivangi; Malvi, Bhupendra; Purohit, P. K.; Gwal, A. K.

2016-10-01

The solar activity hence the solar radiance follows a long term periodic variability with eleven years periodicity, known as solar cycle. This drives the long term variability of the ionosphere. In the present problem we investigate the long term behaviour of the ionosphere with the eleven year cyclic solar activity. Under the present study we characterize the ionospheric variability by Total Electron Content (TEC) using measurements made by Global Positioning System (GPS) and solar cycle variability by various solar activity indices. We make use of five solar activity indices viz. sunspot number (Rz), solar radio Flux (F10.7 cm), EUV Flux (26-34 nm), flare index and CME occurrences. The long term variability of these solar activity indices were then compared and correlated with the variability of ionospheric TEC, at a mid latitude station, Usuda (36.13N, 138.36E), of Japan, during the solar cycle 23 and ascending phase of cycle 24. From our study, we found that long term changes in the ionospheric TEC vary synchronously with corresponding changes in the solar activity indices. The correlation analysis shows that all the solar activity indices exhibit a very strong correlation with TEC (R =0.76 -0.99). Moreover the correlation between the two is stronger in the descending phase of the solar cycle. The correlation is found to be remarkably strongest during the deep minimum of the solar cycle 24 i.e. between 2007- 2009. Also we noticed a hysteresis effect exists with solar radio flux (F10.7 cm) and solar EUV flux (26-34 nm). This effect is absent with other parameters.

Estimating amplitudes of fifth-order sea level fluctuations from peritidal through basinal carbonate deposits, Lower Mississippian, Wyoming-Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elrick, M.; Read, J.F.

1990-05-01

Three types of 1-10-m upward-shallowing cycles are observed in the Lower Mississippian Lodgepole and lower Madison formations of Wyoming and Montana. Typical peritidal cycles have pellet grainstone bases overlain by algal laminites, which are rarely capped by paleosol/regolith horizons. Shallow ramp cycles have burrowed pellet-skeletal wackestone bases overlain by cross-bedded ooid/crinoid grainstone caps. Deep ramp cycles are characterized by sub-wave base limestone/argillite, storm-deposited limestone, overlain by hummocky stratified grainstone caps. Average cycle periods range from 17-155 k.y. This, rhythmically bedded limestone/argillite deposits of basinal facies do not contain shallowing-upward cycles, but do contain 2-4 k.y. limestone/argillite rhythms. These sub-wave basemore » deposit are associated with Waulsortian-type mud mounds which have >50 m synoptic relief. This relief provides minimum water depth estimates for the deposits, and implies storm-wave base was less than 50 m. Two-dimensional computer modeling of cyclic platform through noncyclic basinal deposits allows for bracketing of fifth-order sea level fluctuation amplitudes, thought responsible for cycle formation. Computer models using fifth-order amplitudes less than 20 m do not produce cycles on the deep ramp (assuming a 25-30 m storm-wave base). Amplitudes >30 m produce water depths on the inner ramp that are too deep, and disconformities extend too far into the basin. The absence of meter-scale cycles in the basin suggests water depths were too great to record the effects of sea level oscillations occurring on the platform, or climatic fluctuation, associated with glacio-eustatic sea level oscillations, were not sufficient to affect hemipelagic depositional patterns in the tropical basin environment.« less

Springtime microwave emissivity changes in the southern Kara Sea

NASA Technical Reports Server (NTRS)

Crane, Robert G.; Anderson, Mark R.

1994-01-01

Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest that the negative gradient ratios in spring 1982 result from increased scatter at 37 GHz due to the formation of a near-surface hoar layer. This interpretation is supported by the results of a surface radiation balance model that shows the melt signature occurring at below freezing temperatures but under clear-sky conditions with increased solar input to the surface. Published observations from the Greenland ice cap show a surface hoar layer forming under similar atmospheric conditions owing to the increased penetration and absorption of solar radiation just below the surface layer. In spring/early summer 1984 similar gradient ratio signatures occur. They appear to be due to several days of freeze-thaw cycling following the movement of a low-pressure system through the region. These changes in surface emissivity represent the transition from winter to summer conditions (as defined by the microwave response) and are shown to be regional in extent and to vary with the synoptic circulations.

On the variation of the Nimbus 7 total solar irradiance

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

1992-01-01

For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the Nimbus-7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 Wm(exp -2), having a standard deviation of 0.65 Wm(exp -2), a coefficient of variation (mean divided by the standard deviation) of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of -8.019 (inferring a highly significant non-random variation in the solar irradiance measurements, presumably related to the action of the solar cycle). Comparison of the 12-month moving average (also called the 13-month running mean) of solar irradiance to those of the usual descriptors of the solar cycle (i.e., sunspot number, 10.7-cm solar radio flux, and total corrected sunspot area) suggests possibly significant temporal differences. For example, solar irradiance is found to have been greatest on or before mid 1979 (leading solar maximum for cycle 21), lowest in early 1987 (lagging solar minimum for cycle 22), and was rising again through late 1990 (thus, lagging solar maximum for cycle 22), having last reported values below those that were seen in 1979 (even though cycles 21 and 22 were of comparable strength). Presuming a genuine correlation between solar irradiance and the solar cycle (in particular, sunspot number) one infers that the correlation is weak (having a coefficient of correlation r less than 0.84) and that major excursions (both as 'excesses' and 'deficits') have occurred (about every 2 to 3 years, perhaps suggesting a pulsating Sun).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shepherd, Simon J.; Zharkov, Sergei I.; Zharkova, Valentina V., E-mail: s.j.shepherd@brad.ac.uk, E-mail: s.zharkov@hull.ac.uk, E-mail: valentina.zharkova@northumbria.ac.uk

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 differentmore » 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.« less

Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sleiman, Mohamad; Kirchstetter, Thomas W.; Berdahl, Paul

2014-01-09

Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon,more » humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products₋single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles₋and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. In conclusion, this accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.« less

Observations and modeling of northern mid-latitude recurring slope lineae (RSL) suggest recharge by a present-day martian briny aquifer

NASA Astrophysics Data System (ADS)

Stillman, David E.; Michaels, Timothy I.; Grimm, Robert E.; Hanley, Jennifer

2016-02-01

Recurring slope lineae (RSL) are narrow (0.5-5 m) dark features on Mars that incrementally lengthen down steep slopes, fade in colder seasons, and recur annually. These features have been identified from the northern to southern mid-latitudes. Here, we describe how observations of northern mid-latitude RSL in northern Chryse Planitia and southwestern Acidalia Planitia (CAP) suggest that brines start flowing before northern spring equinox and continue for more than half a Mars-year (490 ± 40 sols, spanning solar longitude 337° ± 11°-224° ± 20°). All CAP RSL are found on the steep slopes of craters and their source zones are at or below the elevation of the surrounding plains. Spacecraft-derived surface temperature observations cannot resolve individual RSL, so thermal modeling was used to determine that CAP RSL have a freezing temperature of 238-252 K, freeze and melt diurnally, and flow only occurs within the top ∼8 cm of the regolith. Furthermore, we calculate that a typical CAP RSL has a water budget of 1.5-5.6 m3/m of headwall. Therefore, such a large water budget makes annual recharge via atmospheric or subsurface diffusion sources unlikely. Alternatively, we hypothesize that the most plausible RSL source is a briny aquifer with a freezing temperature less than or equal to the mean annual CAP surface temperature (220-225 K). The annual cycle is as follows: in late autumn, the shallowest part of the brine feeding the source zone freezes, forming an ice dam. As spring approaches, temperatures rise and the dam is breached. Brine is discharged and the RSL initially lengthens rapidly (>1.86 m/sol), the lengthening rate then slows considerably, to ∼0.25 m/sol. Eventually, the losses equal the discharge rate and the RSL reaches its equilibrium phase. As brine flows in the RSL some of the water is lost to the atmosphere, therefore the freezing temperature of the brine within the RSL is higher (238-252 K) as the brine transitions to a super-eutectic salt concentration. In the late autumn, falling temperatures restore the ice dam and the H2O in the RSL slowly sublimates away. Overall, CAP RSL possess a significantly different seasonality and much longer duration than typical southern mid-latitude RSL, suggesting that RSL at different latitude bands have different source types. Lastly, CAP RSL are the best evidence that shallow groundwater may still exist on Mars.

Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Szoeke, Simon P.

The investigator and DOE-supported student [1] retrieved vertical air velocity and microphysical fall velocity retrieval for VOCALS and CAP-MBL homogeneous clouds. [2] Calculated in-cloud and cloud top dissipation calculation and diurnal cycle computed for VOCALS. [3] Compared CAP-MBL Doppler cloud radar scenes with (Remillard et al. 2012) automated classification.

Early Estimation of Solar Activity Cycle: Potential Capability and Limits

NASA Technical Reports Server (NTRS)

Kitiashvili, Irina N.; Collins, Nancy S.

2017-01-01

The variable solar magnetic activity known as the 11-year solar cycle has the longest history of solar observations. These cycles dramatically affect conditions in the heliosphere and the Earth's space environment. Our current understanding of the physical processes that make up global solar dynamics and the dynamo that generates the magnetic fields is sketchy, resulting in unrealistic descriptions in theoretical and numerical models of the solar cycles. The absence of long-term observations of solar interior dynamics and photospheric magnetic fields hinders development of accurate dynamo models and their calibration. In such situations, mathematical data assimilation methods provide an optimal approach for combining the available observational data and their uncertainties with theoretical models in order to estimate the state of the solar dynamo and predict future cycles. In this presentation, we will discuss the implementation and performance of an Ensemble Kalman Filter data assimilation method based on the Parker migratory dynamo model, complemented by the equation of magnetic helicity conservation and longterm sunspot data series. This approach has allowed us to reproduce the general properties of solar cycles and has already demonstrated a good predictive capability for the current cycle, 24. We will discuss further development of this approach, which includes a more sophisticated dynamo model, synoptic magnetogram data, and employs the DART Data Assimilation Research Testbed.

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.

Economic and Environmental Consequences of Widespread Expansion of Solar energy

NASA Astrophysics Data System (ADS)

Satija, Gaurav

The purpose of the thesis is to examine the sustainability of an expansion in solar energy subject to resource constraints of Indium. Coal and natural gas are taken as competitors for solar in the energy market. The consumer electronics market also competes with solar PV production because of Indium's use in the manufacturing of LCD screens. A partial equilibrium model is made which determines the rate of extraction of indium, coal and natural gas endogenously. Consumer demand is modeled by the use of cost shares. Generation of electricity and production of LCDs are modeled using Constant Elasticity of Substitution functions. Initial production capacity for both electricity and LCD is considered in the model. The model then endogenously determines the level of investment required. Model simulations are performed to predict the extraction paths and production levels for a timeline of 100 years. A sensitivity analysis is performed to see the reaction of the model to changes in consumer demand and learning rates in solar energy. The response of the model to imposition of various emission caps is also shown. Results of the model show that indium scarcity prevents solar from expanding significantly to a level where it can take over from non-renewable sources of energy. Increased research in solar technologies would not be of much help unless more Indium is available, either by recycling of solar PVs and LCDs or searching for alternate technologies to manufacture LCD screes. Emission caps are able to control excessive usage of fossil fuels and preserve them for a longer time.

A Two Dimensional Prediction of Solar Cycle 25

NASA Astrophysics Data System (ADS)

Munoz-Jaramillo, A.; Martens, P. C.

2017-12-01

To this date solar cycle most cycle predictions have focused on the forecast of solar cycle amplitude and cycle bell-curve shape. However, recent intriguing observational results suggest that all solar cycles follow the same longitudinal path regardless of their amplitude, and have a very similar decay once they reach a sufficient level of maturity. Cast in the light of our current understanding, these results suggest that the toroidal fields inside the Sun are subject to a very high turbulent diffusivity (of the order of magnitude of mixing-length estimates), and their equatorward propagation is driven by a steady meridional flow. Assuming this is the case, we will revisit the relationship between the polar fields at minimum and the amplitude of the next cycle and deliver a new generation of polar-field based predictions that include the depth of the minimum, as well as the latitude and time of the first active regions of solar cycle 25.

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.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usoskin, Ilya G.; Mursula, Kalevi; Arlt, Rainer

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 themore » 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.« less

Estimate of the effect of the 11-year solar activity cycle on the ozone content in the stratosphere

NASA Astrophysics Data System (ADS)

Gruzdev, A. N.

2014-09-01

Using spectral, cross-spectral, and regression methods, we analyzed the effect of the 11-year cycle of solar activity on the ozone content in the stratosphere and lower mesosphere via satellite measurement data obtained with the help of SBUV/SBUV2 instruments in 1978-2003. We revealed a high coherence between the ozone content and solar activity level on the solar cycle scale. In much of this area, the ozone content varies approximately in phase with the solar cycle; however, in areas of significant gradients of ozone mixing ratio in the middle stratosphere, the phase shift between ozone and solar oscillations can be considerable, up to π/2. This can be caused by dynamical processes. The altitude maxima of ozone sensitivity to the 11-year solar cycle were found in the upper vicinity of the stratopause (50-55 km), in the middle stratosphere (35-40 km), and the lower stratosphere (below 25 km). Maximal changes in ozone content in the solar cycle (up to 10% and more) were found in winter and spring in polar regions.

The Effect of a Potentially Low Solar Cycle #24 on Orbital Lifetimes of Fengyun 1-C Debris

NASA Technical Reports Server (NTRS)

Whitlock, David; Johnson, Nicholas; Matney, Mark; Krisko, Paula

2008-01-01

The magnitude of Solar Cycle #24 will have a non-trivial impact on the lifetimes of debris pieces that resulted from the intentional hypervelocity impact of the Fengyun 1-C satellite in January 2007. Recent solar flux measurements indicate Solar Cycle #24 has begun in the last few months, and will continue until approximately 2019. While there have been differing opinions on whether the intensity of this solar cycle will be higher or lower than usual, the Space Weather Prediction Center within the National Oceanic Atmospheric Administration (NOAA/SWPC) has recently forecast unusually low solar activity, which would result in longer orbital lifetimes. Using models for both the breakup of Fengyun 1-C and the propagation of the resultant debris cloud, the Orbital Debris Program Office at NASA Johnson Space Center conducted a study to better understand the impact of the solar cycle on lifetimes for pieces as small as 1 mm. Using a modified collision breakup model and PROP3D propagation software, the orbits of nearly 2 million objects 1 mm and larger were propagated for up to 200 years. By comparing a normal solar cycle with that of the NOAA/SWPC forecast low cycle, the effect of the solar flux on the lifetimes of the debris pieces is evaluated. The modeling of the low solar cycle shows an additional debris count of 12% for pieces larger than 10 cm by 2019 when compared to the resultant debris count using a normal cycle. The difference becomes more exaggerated (over 15%) for debris count in the smaller size regimes. However, in 50 years, the models predict the differences in debris count from differing models of Solar Cycle #24 to be less than 10% for all size regimes, with less variance in the smaller sizes. Understanding the longevity of the debris cloud will affect collision probabilities for both operational spacecraft and large derelict objects over the next century and beyond.

Statistical properties of superactive regions during solar cycles 19-23

NASA Astrophysics Data System (ADS)

Chen, A. Q.; Wang, J. X.; Li, J. W.; Feynman, J.; Zhang, J.

2011-10-01

Context. Each solar activity cycle is characterized by a small number of superactive regions (SARs) that produce the most violent of space weather events with the greatest disastrous influence on our living environment. Aims: We aim to re-parameterize the SARs and study the latitudinal and longitudinal distributions of SARs. Methods: We select 45 SARs in solar cycles 21-23, according to the following four parameters: 1) the maximum area of sunspot group, 2) the soft X-ray flare index, 3) the 10.7 cm radio peak flux, and 4) the variation in the total solar irradiance. Another 120 SARs given by previous studies of solar cycles 19-23 are also included. The latitudinal and longitudinal distributions of the 165 SARs in both the Carrington frame and the dynamic reference frame during solar cycles 19-23 are studied statistically. Results: Our results indicate that these 45 SARs produced 44% of all the X class X-ray flares during solar cycles 21-23, and that all the SARs are likely to produce a very fast CME. The latitudinal distributions of SARs display the Maunder butterfly diagrams and SARs occur preferentially in the maximum period of each solar cycle. Northern hemisphere SARs dominated in solar cycles 19 and 20 and southern hemisphere SARs dominated in solar cycles 21 and 22. In solar cycle 23, however, SARs occurred about equally in each hemisphere. There are two active longitudes in both the northern and southern hemispheres, about 160°-200° apart. Applying the improved dynamic reference frame to SARs, we find that SARs rotate faster than the Carrington rate and there is no significant difference between the two hemispheres. The synodic periods are 27.19 days and 27.25 days for the northern and southern hemispheres, respectively. The longitudinal distribution of SARs is significantly non-axisymmetric and about 75% SARs occurred near two active longitudes with half widths of 45°. Appendix A is available in electronic form at http://www.aanda.org

Implications of summertime marine stratocumulus on the North American climate

NASA Technical Reports Server (NTRS)

Clark, John H. E.

1994-01-01

This study focuses on the effects of summertime stratocumulus over the eastern Pacific. This cloud is linked to the semi-permanent sub-tropical highs that dominate the low-level circulation over the Pacific and Atlantic. Subsidence on the eastern flank of these highs creates an inversion based about 800 m above sea level that caps moist air near the surface. This air overlies cool waters driven by upwelling along the coastal regions of North America. Strong surface north-westerlies mix the boundary layer enough to saturate the air just below the capping inversion. Widespread stratocumulus is thus formed. All calculations were carried out using the GENESIS general circulation model that was run at MSFC. Among the more important properties of the model is that it includes radiative forcing due to absorption of solar radiation and the emission of infrared radiation, interactive clouds (both stratocumulus and cumulus types), exchanges of heat and moisture with the lower boundary. Clouds are interactive in the sense that they impact the circulation by modifying the fields of radiative heating and turbulent fluxes of heat and moisture in the boundary layer. In turn, clouds are modified by the winds through the advection of moisture. In order to isolate the effects of mid- and high-latitude stratocumulus, two runs were made with the model: one with and the other without stratocumulus. The runs were made for a year, but with perpetual July conditions, i.e., solar forcing was fixed. The diurnal solar cycle, however, was allowed for. The sea surface temperature distribution was fixed in both runs to represent climatological July conditions. All dependent variables were represented at 12 surfaces of constant sigma = p/p(sub O), where p is pressure and p(sub O) is surface pressure. To facilitate analysis, model output was transformed to constant pressure surfaces. Structures no smaller in size than 7.5 degrees longitude and 4.5 degrees in latitude were resolved. Smaller features of the circulation were parameterized. The model thus captures synoptic- and planetary-scale circulation features.

Simulations of the general circulation of the Martian atmosphere. II - Seasonal pressure variations

NASA Technical Reports Server (NTRS)

Pollack, James B.; Haberle, Robert M.; Murphy, James R.; Schaeffer, James; Lee, Hilda

1993-01-01

The CO2 seasonal cycle of the Martian atmosphere and surface is simulated with a hybrid energy balance model that incorporates dynamical and radiation information from a large number of general circulation model runs. This information includes: heating due to atmospheric heat advection, the seasonally varying ratio of the surface pressure at the two Viking landing sites to the globally averaged pressure, the rate of CO2 condensation in the atmosphere, and solar heating of the atmosphere and surface. The predictions of the energy balance model are compared with the seasonal pressure variations measured at the two Viking landing sites and the springtime retreat of the seasonal polar cap boundaries. The following quantities are found to have a strong influence on the seasonal pressures at the Viking landing sites: albedo of the seasonal CO2 ice deposits, emissivity of this deposit, atmospheric heat advection, and the pressure ratio.

Simple energy balance model resolving the seasons and the continents - Application to the astronomical theory of the ice ages

NASA Technical Reports Server (NTRS)

North, G. R.; Short, D. A.; Mengel, J. G.

1983-01-01

An analysis is undertaken of the properties of a one-level seasonal energy balance climate model having explicit, two-dimensional land-sea geography, where land and sea surfaces are strictly distinguished by the local thermal inertia employed and transport is governed by a smooth, latitude-dependent diffusion mechanism. Solutions of the seasonal cycle for the cases of both ice feedback exclusion and inclusion yield good agreements with real data, using minimal turning of the adjustable parameters. Discontinuous icecap growth is noted for both a solar constant that is lower by a few percent and a change of orbital elements to favor cool Northern Hemisphere summers. This discontinuous sensitivity is discussed in the context of the Milankovitch theory of the ice ages, and the associated branch structure is shown to be analogous to the 'small ice cap' instability of simpler models.

Ulysses breaks latitude record

NASA Astrophysics Data System (ADS)

1993-06-01

Ulysses is gathering important new information concerning the Sun and its environment. Its prime mission objective is to carry out the first systematic exploration of the inner part of the heliosphere - the region of space carved out of the interstellar medium by the solar wind - at all latitudes from the solar equator to the poles. The spacecraft, launched by the space shuttle Discovery on 6 October 1990 in the framework of an ESA-NASA collaborative venture, underwent a gravity assist manoeuvre at Jupiter in February 1992 and is now in a highly inclined solar orbit that will bring it over the south pole of the Sun in September 1994. At that time, Ulysses will establish a new record as it climbs to its maximum latitude of just over 80 degrees. The spacecraft and its scientific instruments are in excellent condition and the data coverage since launch has been consistently close to 100% thanks to the dedicated efforts of the joint ESA-NASA Mission Operations Team and NASA's Deep Space Network. Although the most exciting phase of the mission - the study of the Sun's polar regions - will only begin in mid-1994, Ulysses has already produced a wealth of new scientific results. These include : * - The first direct detection of neutral helium atoms arriving from interstellar space. * - The measurement of micron-sized dust grains arriving from interstellar space. * - The first measurement of singly-charged H, N, O and Ne ions which entered the heliosphere as interstellar neutral atoms and were then ionised. * - The highest-resolution measurements to date of the isotopic composition of cosmic ray nuclei (e.g. C, N, O, Ne, Si and Mg). In addition to the above, the traversal of Jupiter's magnetosphere at the time of the fly-by enabled the Ulysses investigators to acquire new and highly valuable data concerning this very complex and dynamic plasma environment. Among the more exciting results to emerge are the possible entry into the polar cap of Jupiter's magnetosphere near the time of closest approach, and the unexpectedly strong influence of the solar wind deep in the magnetosphere during the outbound passage. With the Jupiter fly-by safely accomplished, the scientific focus is now directed towards phenomena related to the increasing latitute of the spacecraft. Already, there is strong evidence that Ulysses is now in the domain of the southern polar magnetic field. By a fortunate coincidence, just as Ulysses was reaching 32 degrees South, the magnetic field and plasma analyser scientific teams were seeing the first evidence of the effect of increasing latitude on the magnetised solar wind. The two complementary sets of observations reveal the passage of Ulysses into a magnetic unipolar regime corresponding to latitudes above the sunspot belt, having permanently crossed the boundary separating northern and southern magnetic fields. Following the flight over the Sun's southern pole, Ulysses' orbit will bring the spaceprobe swinging back towards the equatorial regions, heading for its second high-latitude excursion in mid-1995, this time above the North polar regions. "By the end of September 1995, Ulysses will have put our knowledge of the Sun and its environment in a completely new perspective", says Dr. Marsden, ESA's Project Scientist for Ulysses. "Only by studying the way the Sun influences the space around it in a global manner can we hope to understand its influence on our local interplanetary environment". An example of this "local" influence is the disturbance experienced by technical systems in Earth orbit and on the ground (e.g., telecommunications systems) at the time of major solar flares. Note to the Editors: Near the Sun's equatorial regions, the interplanetary magnetic field alternately points toward and away from the Sun during a single solar rotation which gives rise to so-called magnetic sectors. The existence of these sectors is interpreted as the effect of a vast current sheet, tilted with respect to the Sun's rotation axis, which separates oppositely-directed magnetic fields from the North and South polar caps. The recent Ulysses magnetic field observations reveal a single polarity, i.e. the disappearance of magnetic sectors. This implies that Ulysses is now above the current sheet. The polarity of the observed fields corresponds to that of the Sun's south polar cap as would be expected. Concurrent with the magnetic sector disappearance, the Ulysses solar wind plasma instrument, which detects solar wind ions and electrons, shows a persistently fast solar wind flow. High speed solar wind is thought to issue from coronal holes (regions of reduced X-ray brightness and density in the Sun's corona), and it is known that extended coronal holes cover each of the polar caps at this phase of the solar cycle. The Ulysses observations are interpreted as indicating that the spacecraft has now entered the region above the southern polar coronal hole.

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.

Design Investigation of Solar Powered Lasers for Space Applications

DTIC Science & Technology

1979-05-01

Brayton Cycle Power Units 64 3.4 Heat Exchanger 75 3.5 Waste Heat Radiator 79 3.6 Solar Powered Gas Dynamic Laser 82 3.7 Solar Powered Electric... Brayton Cycle Space Power Units 65 10 Supersonic C02 GDL (1 MW) 85 11 Specific Weights for Comparative Evaluation of Solar Lasers 88 12 Subsonic C02...for the Brayton Cycle Power Units 61 21 Solar Radiation Boiler-Receiver Solar Radiation from the Collectors in Focussed (at left) on the

The "Approximate 150 Day Quasi-Periodicity" in Interplanetary and Solar Phenomena During Cycle 23

NASA Technical Reports Server (NTRS)

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

2004-01-01

A"quasi-periodicity" of approx. 150 days in various solar and interplanetary phenomena has been reported in earlier solar cycles. We suggest that variations in the occurrence of solar energetic particle events, inter-planetary coronal mass ejections, and geomagnetic storm sudden commenceents during solar cycle 23 show evidence of this quasi-periodicity, which is also present in the sunspot number, in particular in the northern solar hemisphere. It is not, however, prominent in the interplanetary magnetic field strength.

Solar proton fluxes since 1956. [sunspot activity correlation

NASA Technical Reports Server (NTRS)

Reedy, R. C.

1977-01-01

The fluxes of protons emitted during solar flares since 1956 were evaluated. The depth-versus-activity profiles of Co-56 in several lunar rocks are consistent with the solar proton fluxes detected by experiments on several satellites. Only about 20% of the solar-proton-induced activities of Na-22 and Fe-55 in lunar rocks from early Apollo missions were produced by protons emitted from the sun during solar cycle 20 (1965-1975). The depth-versus-activity data for these radionuclides in several lunar rocks were used to determine the fluxes of protons during solar cycle 19 (1954-1964). The average proton fluxes for cycle 19 are about five times those for both the last million years and for cycle 20 and are about five times the previous estimate for cycle 19 based on neutron-monitor and radio ionospheric measurements. These solar-proton flux variations correlate with changes in sunspot activity.

Improvement of solar-cycle prediction: Plateau of solar axial dipole moment

NASA Astrophysics Data System (ADS)

Iijima, H.; Hotta, H.; Imada, S.; Kusano, K.; Shiota, D.

2017-11-01

Aims: We report the small temporal variation of the axial dipole moment near the solar minimum and its application to the solar-cycle prediction by the surface flux transport (SFT) model. Methods: We measure the axial dipole moment using the photospheric synoptic magnetogram observed by the Wilcox Solar Observatory (WSO), the ESA/NASA Solar and Heliospheric Observatory Michelson Doppler Imager (MDI), and the NASA Solar Dynamics Observatory Helioseismic and Magnetic Imager (HMI). We also use the SFT model for the interpretation and prediction of the observed axial dipole moment. Results: We find that the observed axial dipole moment becomes approximately constant during the period of several years before each cycle minimum, which we call the axial dipole moment plateau. The cross-equatorial magnetic flux transport is found to be small during the period, although a significant number of sunspots are still emerging. The results indicate that the newly emerged magnetic flux does not contribute to the build up of the axial dipole moment near the end of each cycle. This is confirmed by showing that the time variation of the observed axial dipole moment agrees well with that predicted by the SFT model without introducing new emergence of magnetic flux. These results allow us to predict the axial dipole moment at the Cycle 24/25 minimum using the SFT model without introducing new flux emergence. The predicted axial dipole moment at the Cycle 24/25 minimum is 60-80 percent of Cycle 23/24 minimum, which suggests the amplitude of Cycle 25 is even weaker than the current Cycle 24. Conclusions: The plateau of the solar axial dipole moment is an important feature for the longer-term prediction of the solar cycle based on the SFT model.

Comparison of Model and Observations of Middle Atmospheric HOx Response to Solar 27-day Cycles: Quantifying Model Uncertainties due to Photochemistry

NASA Astrophysics Data System (ADS)

Wang, S.; Li, K. F.; Shia, R. L.; Yung, Y. L.; Sander, S. P.

2016-12-01

HO2 and OH (known as odd oxygen HOx), play an important role in middle atmospheric chemistry, in particular, O3 destruction through catalytic HOx reaction cycles. Due to their photochemical production and short chemical lifetimes, HOx species response rapidly to solar UV irradiance changes during solar cycles, resulting in variability in the corresponding O3 chemistry. Observational evidences for both OH and HO2 variability due to solar cycles have been reported. However, puzzling discrepancies remain. In particular, the large discrepancy between model and observations of solar 11-year cycle signal in OH and the significantly different model results when adopting different solar spectral irradiance (SSI) [Wang et al., 2013] suggest that both uncertainties in SSI variability and uncertainties in our current understanding of HOx-O3 chemistry could contribute to the discrepancy. Since the short-term SSI variability (e.g. changes during solar 27-day cycles) has little uncertainty, investigating 27-day solar cycle signals in HOx allows us to simplify the complex problem and to focus on the uncertainties in chemistry alone. We use the Caltech-JPL photochemical model to simulate observed HOx variability during 27-day cycles. The comparison between Aura Microwave Limb Sounder (MLS) observations and our model results (using standard chemistry and "adjusted chemistry", respectively) will be discussed. A better understanding of uncertainties in chemistry will eventually help us separate the contribution of chemistry from contributions of SSI uncertainties to the complex discrepancy between model and observations of OH responses to solar 11-year cycles.

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. This appears consistent with a weakening polar field, but coronal hole data must be scrutinized carefully as observing techniques have changed. We also discuss new solar dynamo ideas, and the SODA (SOlar Dynamo Amplitude) index, which provides the user with the ability to track the Sun's hidden, dynamo magnetic fields throughout the various stages of the Sun's cycle. Our solar dynamo ideas are a modernization and rejuvenation of the Babcock-Leighton original idea of a shallow solar dynamo, using modern observations that appear to support their shallow dynamo viewpoint. We are in awe of being able to see an object the size of the Sun undergoing as dramatic a change as our model provides in a few short years. The Sun, however, has undergone changes as rapid as this before! The weather on the Sun is at least as fickle as the weather on the Earth.

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 consistent with a weakening polar field, but coronal hole data must be scrutinized carefully as observing techniques have changed. We also discuss new solar dynamo ideas, and the SODA (Solar Dynamo Amplitude) index, which provides the user with the ability to track the Sun s hidden, dynamo magnetic fields throughout the various stages of the Sun s cycle. Our solar dynamo ideas are a modernization and rejuvenation of the Babcock-Leighton original idea of a shallow solar dynamo, using modem observations that appear to support their shallow dynamo viewpoint. We are in awe of being able to see an object the size of the Sun undergoing as dramatic a change as our model provides in a few short years. The Sun, however, has undergone changes as rapid as this before! The weather on the Sun is at least as fickle as the weather on the Earth.

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.

Prediction of the total cycle 24 of solar activity by several autoregressive methods and by the precursor method

NASA Astrophysics Data System (ADS)

Ozheredov, V. A.; Breus, T. K.; Obridko, V. N.

2012-12-01

As follows from the statement of the Third Official Solar Cycle 24 Prediction Panel created by the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the International Space Environment Service (ISES) based on the results of an analysis of many solar cycle 24 predictions, there has been no consensus on the amplitude and time of the maximum. There are two different scenarios: 90 units and August 2012 or 140 units and October 2011. The aim of our study is to revise the solar cycle 24 predictions by a comparative analysis of data obtained by three different methods: the singular spectral method, the nonlinear neural-based method, and the precursor method. As a precursor for solar cycle 24, we used the dynamics of the solar magnetic fields forming solar spots with Wolf numbers Rz. According to the prediction on the basis of the neural-based approach, it was established that the maximum of solar cycle 24 is expected to be 70. The precursor method predicted 50 units for the amplitude and April of 2012 for the time of the maximum. In view of the fact that the data used in the precursor method were averaged over 4.4 years, the amplitude of the maximum can be 20-30% larger (i.e., around 60-70 units), which is close to the values predicted by the neural-based method. The protracted minimum of solar cycle 23 and predicted low values of the maximum of solar cycle 24 are reminiscent of the historical Dalton minimum.

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 in the long-range predictions remains, requiring future monitoring, we do not expect the next cycle's + 2-sigma value will rise significantly above solar cycle #23's activity level.

Statistical Methods for Quantifying the Variability of Solar Wind Transients of All Sizes

NASA Astrophysics Data System (ADS)

Tindale, E.; Chapman, S. C.

2016-12-01

The solar wind is inherently variable across a wide range of timescales, from small-scale turbulent fluctuations to the 11-year periodicity induced by the solar cycle. Each solar cycle is unique, and this change in overall cycle activity is coupled from the Sun to Earth via the solar wind, leading to long-term trends in space weather. Our work [Tindale & Chapman, 2016] applies novel statistical methods to solar wind transients of all sizes, to quantify the variability of the solar wind associated with the solar cycle. We use the same methods to link solar wind observations with those on the Sun and Earth. We use Wind data to construct quantile-quantile (QQ) plots comparing the statistical distributions of multiple commonly used solar wind-magnetosphere coupling parameters between the minima and maxima of solar cycles 23 and 24. We find that in each case the distribution is multicomponent, ranging from small fluctuations to extreme values, with the same functional form at all phases of the solar cycle. The change in PDF is captured by a simple change of variables, which is independent of the PDF model. Using this method we can quantify the quietness of the cycle 24 maximum, identify which variable drives the changing distribution of composite parameters such as ɛ, and we show that the distribution of ɛ is less sensitive to changes in its extreme values than that of its constituents. After demonstrating the QQ method on solar wind data, we extend the analysis to include solar and magnetospheric data spanning the same time period. We focus on GOES X-ray flux and WDC AE index data. Finally, having studied the statistics of transients across the full distribution, we apply the same method to time series of extreme bursts in each variable. Using these statistical tools, we aim to track the solar cycle-driven variability from the Sun through the solar wind and into the Earth's magnetosphere. Tindale, E. and S.C. Chapman (2016), Geophys. Res. Lett., 43(11), doi: 10.1002/2016GL068920.

Solar cycle variations of the solar wind

NASA Technical Reports Server (NTRS)

Crooker, N. U.

1983-01-01

Throughout the course of the past one and a half solar cycles, solar wind parameters measured near the ecliptic plane at 1 AU varied in the following way: speed and proton temperature have maxima during the declining phase and minima at solar minimum and are approximately anti-correlated with number density and electron temperature, while magnetic field magnitude and relative abundance of helium roughly follow the sunspot cycle. These variations are described in terms of the solar cycle variations of coronal holes, streamers, and transients. The solar wind signatures of the three features are discussed in turn, with special emphasis on the signature of transients, which is still in the process of being defined. It is proposed that magnetic clouds be identified with helium abundance enhancements and that they form the head of a transient surrounded by streamer like plasma, with an optional shock front. It is stressed that relative values of a parameter through a solar cycle should be compared beginning with the declining phase, especially in the case of magnetic field magnitude.

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

Understanding Solar Cycle Variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cameron, R. H.; Schüssler, M., E-mail: cameron@mps.mpg.de

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 amore » 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.« less

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.

Imprint of long-term solar signal in groundwater recharge fluctuation rates from Northwest China

NASA Astrophysics Data System (ADS)

Tiwari, R. K.; Rajesh, Rekapalli

2014-05-01

Multiple spectral and statistical analyses of a 700 yearlong temporal record of groundwater recharge from the dry lands, Badain Jaran Desert (Inner Mongolia) of Northwest China reveal a stationary harmonic cycle at ~200 ± 20 year. Interestingly, the underlying periodicity in groundwater recharge fluctuations is similar to those of solar-induced climate cycle "Suess wiggles" and appears to be coherent with phases of the climate fluctuations and solar cycles. Matching periodicity of groundwater recharge rates and solar and climate cycles renders a strong impression that solar-induced climate signals may act as a critical amplifier for driving the underlying hydrographic cycle through the common coupling of long-term Sun-climate groundwater linkages.

Solar prediction analysis

NASA Technical Reports Server (NTRS)

Smith, Jesse B.

1992-01-01

Solar Activity prediction is essential to definition of orbital design and operational environments for space flight. This task provides the necessary research to better understand solar predictions being generated by the solar community and to develop improved solar prediction models. The contractor shall provide the necessary manpower and facilities to perform the following tasks: (1) review, evaluate, and assess the time evolution of the solar cycle to provide probable limits of solar cycle behavior near maximum end during the decline of solar cycle 22, and the forecasts being provided by the solar community and the techniques being used to generate these forecasts; and (2) develop and refine prediction techniques for short-term solar behavior flare prediction within solar active regions, with special emphasis on the correlation of magnetic shear with flare occurrence.

The sun and heliosphere at solar maximum

NASA Technical Reports Server (NTRS)

Smith, E. J.; Marsden, R. G.; Balogh, A.; Gloeckler, G.; Geiss, J.; McComas, D. J.; McKibben, R. B.; MacDowall, R. J.; Lanzerotti, L. J.; Krupp, N.;

Temporal Variation of the Rotation of the Solar Mean Magnetic Field

NASA Astrophysics Data System (ADS)

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

2017-04-01

Based on continuous wavelet transformation analysis, the daily solar mean magnetic field (SMMF) from 1975 May 16 to 2014 July 31 is analyzed to reveal its rotational behavior. Both the recurrent plot in Bartels form and the continuous wavelet transformation analysis show the existence of rotational modulation in the variation of the daily SMMF. The dependence of the rotational cycle lengths on solar cycle phase is also studied, which indicates that the yearly mean rotational cycle lengths generally seem to be longer during the rising phase of solar cycles and shorter during the declining phase. The mean rotational cycle length for the rising phase of all of the solar cycles in the considered time is 28.28 ± 0.67 days, while for the declining phase it is 27.32 ± 0.64 days. The difference of the mean rotational cycle lengths between the rising phase and the declining phase is 0.96 days. The periodicity analysis, through the use of an auto-correlation function, indicates that the rotational cycle lengths have a significant period of about 10.1 years. Furthermore, the cross-correlation analysis indicates that there exists a phase difference between the rotational cycle lengths and solar activity.

Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses

NASA Astrophysics Data System (ADS)

Volotskova, Olga

Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. Depending on the configuration the cold plasma sources can be used in the following areas: wound healing, skin diseases, hospital hygiene, sterilization, antifungal treatments, dental care, cosmetics targeted cell/tissue removal, and cancer treatments. This dissertation is focused on the studies of biomedical applications of cold atmospheric plasma jet based on helium flow and resultant cell responses to the cold plasma treatment. The studies were carried out on extra-cellular and intra-cellular levels in vitro. The main practical applications are wound healing and alternative to existing cancer therapy methods, areas of great interest and significant challenges. The CAP jet was built in the Micropropulsion and Nanotechnology Laboratory of Dr. Michael Keidar, as a part of multidisciplinary collaboration with the GW Medical School (Dr. M.A. Stepp) concerned with plasma medicine and bioengineering studies. Normal and cancer cells have two fundamental behavioral properties, proliferation and motility, which can be evaluated through cell migration rates and cell cycle progression. Various microscopic, spectroscopic and flow cytometry techniques were used to characterize cell responses to the cold plasma treatment. It was found that CAP effect on the cells is localized within the area of the treatment (of around ˜ 5mm in diameter). The migration rates of the normal skin cells can be reduced up to ˜ 40%. However, depending on the cell type the required treatment time is different, thus differential treatment of various cells presented in tissue is possible. The CAP effect on the migration was explained through the changes of the cell surface proteins/integrins. It was also found that normal and cancer cells respond differently to the CAP treatment under the same experimental conditions. CAP is currently being evaluated as a new highly selective alternative addition to existing cancer therapies. It was shown that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. It was also shown that the expression of γH2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle together with significant decrease in EdU-signal of DNA-replicating cells. Thus, newly developed CAP technology was proven to be of a great interest for practical applications in the areas of wound healing and cancer treatment. The identification and explanation of the mechanisms by which CAP affects the cells was presented.

Statistical Patterns of Ionospheric Convection Derived From Mid-latitude, High-Latitude, and Polar SuperDARN HF Radar Observations

NASA Astrophysics Data System (ADS)

Thomas, E. G.; Shepherd, S. G.

2018-04-01

Over the last decade, the Super Dual Auroral Radar Network (SuperDARN) has undergone a dramatic expansion in the Northern Hemisphere with the addition of more than a dozen radars offering improved coverage at mid-latitudes (50°-60° magnetic latitude) and in the polar cap (80°-90° magnetic latitude). In this study, we derive a statistical model of ionospheric convection (TS18) using line-of-sight velocity measurements from the complete network of mid-latitude, high-latitude, and polar radars for the years 2010-2016. These climatological patterns are organized by solar wind, interplanetary magnetic field (IMF), and dipole tilt angle conditions. We find that for weak solar wind driving conditions the TS18 model patterns are largely similar to the average patterns obtained using high-latitude radar data only. For stronger solar wind driving the inclusion of mid-latitude radar data at the equatorward extent of the ionospheric convection can increase the measured cross-polar cap potential (ΦPC) by as much as 40%. We also derive an alternative model organized by the Kp index to better characterize the statistical convection under a range of magnetic activity conditions. These Kp patterns exhibit similar IMF By dependencies as the TS18 model results and demonstrate a linear increase in ΦPC with increasing Kp for a given IMF orientation. Overall, the mid-latitude radars provide a better specification of the flows within the nightside Harang reversal region for moderate to strong solar wind driving or geomagnetic activity, while the polar radars improve the quality of velocity measurements in the deep polar cap under all conditions.

Comparison of ionospheric convection and the transpolar potential before and after solar wind dynamic pressure fronts: implications for magnetospheric reconnection

NASA Astrophysics Data System (ADS)

Boudouridis, A.; Zesta, E.; Lyons, L. R.; Kim, H.-J.; Lummerzheim, D.; Wiltberger, M.; Weygand, J. M.; Ruohoniemi, J. M.; Ridley, A. J.

2012-04-01

The solar wind dynamic pressure, both through its steady state value and through its variations, plays an important role in the determination of the state of the terrestrial magnetosphere and ionosphere, its effects being only secondary to those of the Interplanetary Magnetic Field (IMF). Recent studies have demonstrated the significant effect solar wind dynamic pressure enhancements have on ionospheric convection and the transpolar potential. Further studies have shown a strong response of the polar cap boundary and thus the open flux content of the magnetosphere. These studies clearly illustrate the strong coupling of solar wind dynamic pressure fronts to the terrestrial magnetosphere-ionosphere system. We present statistical studies of the response of Super Dual Auroral Radar Network (SuperDARN) flows, and Assimilative Mapping of Ionospheric Electrodynamics (AMIE) transpolar potentials to sudden enhancements in solar wind dynamic pressure. The SuperDARN results show that the convection is enhanced within both the dayside and nightside ionosphere. The dayside response is more clear and immediate, while the response on the nightside is slower and more evident for low IMF By values. AMIE results show that the overall convection, represented by the transpolar potential, has a strong response immediately after an increase in pressure, with magnitude and duration modulated by the background IMF Bz conditions. We compare the location of the SuperDARN convection enhancements with the location and motion of the polar cap boundary, as determined by POLAR Ultra-Violet Imager (UVI) images and runs of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic model for specific events. We find that the boundary exhibits a poleward motion after the increase in dynamic pressure. The enhanced ionospheric flows and the poleward motion of the boundary on the nightside are both signatures of enhanced tail reconnection, a conclusion that is reinforced by the observation of the enhanced flows crossing the polar cap boundary in selected case studies when simultaneous measurements are available.

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.

TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.

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 frommore » 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.« less

Simulated solar cycle effects on the middle atmosphere: WACCM3 Versus WACCM4

NASA Astrophysics Data System (ADS)

Peck, E. D.; Randall, C. E.; Harvey, V. L.; Marsh, D. R.

2015-06-01

The Whole Atmosphere Community Climate Model version 4 (WACCM4) is used to quantify solar cycle impacts, including both irradiance and particle precipitation, on the middle atmosphere. Results are compared to previous work using WACCM version 3 (WACCM3) to estimate the sensitivity of simulated solar cycle effects to model modifications. The residual circulation in WACCM4 is stronger than in WACCM3, leading to larger solar cycle effects from energetic particle precipitation; this impacts polar stratospheric odd nitrogen and ozone, as well as polar mesospheric temperatures. The cold pole problem, which is present in both versions, is exacerbated in WACCM4, leading to more ozone loss in the Antarctic stratosphere. Relative to WACCM3, a westerly shift in the WACCM4 zonal winds in the tropical stratosphere and mesosphere, and a strengthening and poleward shift of the Antarctic polar night jet, are attributed to inclusion of the QBO and changes in the gravity wave parameterization in WACCM4. Solar cycle effects in WACCM3 and WACCM4 are qualitatively similar. However, the EPP-induced increase from solar minimum to solar maximum in polar stratospheric NOy is about twice as large in WACCM4 as in WACCM3; correspondingly, maximum increases in polar O3 loss from solar min to solar max are more than twice as large in WACCM4. This does not cause large differences in the WACCM3 versus WACCM4 solar cycle responses in temperature and wind. Overall, these results provide a framework for future studies using WACCM to analyze the impacts of the solar cycle on the middle atmosphere.

Measurements of the Solar Spectral Irradiance Variability over Solar Cycles 21 to 24

NASA Astrophysics Data System (ADS)

Woods, T. N.

2017-12-01

The solar irradiance is the primary natural energy input into Earth's atmosphere and climate system. Understanding the long-term variations of the solar spectral irradiance (SSI) over time scales of the 11-year solar activity cycle and longer is critical for most Sun-climate research topics. There are satellite measurements of the SSI since the 1970s that contribute to understanding the solar cycle variability over Solar Cycles 21 to 24. A limiting factor for the accuracy of these results is the uncertainties for the instrument degradation corrections, for which there are fairly large corrections relative to the amount of solar cycle variability at some wavelengths. A summary of these satellite SSI measurements, which are primarily in the ultraviolet and only recently in the visible and near infrared, will be presented. Examining SSI trends using a new analysis technique is helping to identify some uncorrected instrumental trends, which once applied to the SSI trends has the potential to provide more accurate solar cycle variability results. This new technique examines the SSI trends at different levels of solar activity to provide long-term trends in a SSI record, and one of the most common components of these derived long-term trends is a downward trend that we attribute to being most likely from uncorrected instrument degradation. Examples of this analysis will be presented for some of the satellite SSI measurements to demonstrate this new technique and how it has potential to improve the understanding of solar cycle variability and to clarify the uncertainties of the trends.

H-alpha synoptic charts of solar activity during the first year of solar cycle 20, October 1964 - August 1965. [Skylab program

NASA Technical Reports Server (NTRS)

Mcintosh, P. S.

1975-01-01

Solar activity during the period October 28, 1964 through August 27, 1965 is presented in the form of charts for each solar rotation constructed from observations made with the chromospheric H-alpha spectra line. These H-alpha synoptic charts are identical in format and method of construction to those published for the period of Skylab observations. The sunspot minimum marking the start of Solar Cycle 20 occurred in October, 1964; therefore, charts represent solar activity during the first year of this solar cycle.

Field Line Mapping of the Polar Cap Neutral Density Anomaly

NASA Astrophysics Data System (ADS)

Sutton, E. K.; Lin, C. S.; Huang, C. Y.; Cooke, D. L.

2016-12-01

Polar cap neutral density anomaly (PCNDA) events of localized density enhancement with a half size around 700-1000 km had been frequently detected by CHAMP satellite at around 400 km during major magnetic storms with Dst < -100 nT. Density enhancement is probably produced via Joule heating of the thermosphere when a significant amount of energy is deposited in the polar cap. We have identified 12 PCNDA events measured by CHAMP during two major magnetic storms including one initiated by a large solar wind pressure pulse. Their density anomaly locations are found to scatter randomly within the polar circle of 80o magnetic latitude in the geomagnetic coordinate. However after transformed to the Geocentric Solar Wind (GSW) coordinates, their locations become aligned in the direction of solar wind velocity. To better understand the polar cap energy deposition we trace magnetic field lines to the magnetosphere up to 30 earth radii from the ionosphere at 400 km using the data-based Tsyganenko T95 and TS05 magnetic field models. Field line tracing is performed in the GSW coordinate along the CHAMP orbit as well as for the whole polar cap. Each traced magnetic field line is classified into one of the three categories, (1) magnetosphere closed field line (MC) crossing the equatorial plane within 30 earth radii, (2) open field line connected to the magnetopause (MP), or (3) open field line connected to the magnetotail lobe (MT). For nine PCNDA events among the 10 events that we are able to conduct tracing, field lines originated from the density anomaly regions are classified as MT. Only one outlier event in association with a very large IMF BZ is classified as MP. Furthermore the separation angle between the density anomaly peak and the MP-MT field line separation point at 400 km on the X- and Z-axes meridian plane varies from -4o to 16o. Based on these results we speculate that convective electric fields and field aligned currents in the ionosphere might be enhanced near the MP-MT separation point during magnetic storms, resulting in intense localized Joule heating of the thermosphere.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1990-09-01

From initial Pioneer Venus observations during the maximum of solar cycle 21 it was evident that the position of the Venus bow shock varies with solar activity. The bow shock radius in the terminator plane changed from 2.4 R{sub v} to 2.1 R{sub v} as solar activity went from maximum to minimum and, as activity has increased in cycle 22, it has increased again. The recent studies of the subsolar region show that the altitude of the nose of the bow shock varies from 1,600 km at solar minimum to 2,200 km at intermediate solar activity in concert with themore » terminator altitude so that the shape remains constant and only the size varies during the solar cycle. Using a gas dynamic model and the observed bow shock location, the authors infer the variation in the size of the effective obstacle during the solar cycle. At solar maximum, the effective obstacle is larger than the ionopause as if a magnetic barrier exists in the inner magnetosheath. This magnetic barrier acts as the effective obstacle deflecting the magnetosheath plasma about 500 km above the surface of Venus. However, at solar minimum the effective obstacle is well below the subsolar ionopause, and some absorption of the solar wind plasma by the Venus neutral atmosphere is suggested by these observations. The dependence of the solar cycle variation of the shock position on the orientation of the interplanetary magnetic field reinforces the idea that planetary ion pickup is important in the interaction of the solar wind with Venus.« less

A Feasibility Study of CO2-Based Rankine Cycle Powered by Solar Energy

NASA Astrophysics Data System (ADS)

Zhang, Xin-Rong; Yamaguchi, Hiroshi; Fujima, Katsumi; Enomoto, Masatoshi; Sawada, Noboru

An experiment study was carried out in order to investigate feasibility of CO2-based Rankine cycle powered by solar energy. The proposed cycle is to achieve a cogeneration of heat and power, which consists of evacuated solar tube collectors, power generating turbine, heat recovery system, and feed pump. The Rankine cycle of the system utilizes solar collectors to convert CO2 into high-temperature supercritical state, used to drive a turbine and produce electrical power. The cycle also recovers thermal energy, which can be used for absorption refrigerator, air conditioning, hot water supply so on for a building. A set of experimental set-up was constructed to investigate the performance of the CO2-based Rankine cycle. The results show the cycle can achieve production of heat and power with reasonable thermodynamics efficiency and has a great potential of the application of the CO2-based Rankine cycle powered by solar energy. In addition, some research interests related to the present study will also be discussed in this paper.

Using Data Assimilation Methods of Prediction of Solar Activity

NASA Technical Reports Server (NTRS)

Kitiashvili, Irina N.; Collins, Nancy S.

2017-01-01

The variable solar magnetic activity known as the 11-year solar cycle has the longest history of solar observations. These cycles dramatically affect conditions in the heliosphere and the Earth's space environment. Our current understanding of the physical processes that make up global solar dynamics and the dynamo that generates the magnetic fields is sketchy, resulting in unrealistic descriptions in theoretical and numerical models of the solar cycles. The absence of long-term observations of solar interior dynamics and photospheric magnetic fields hinders development of accurate dynamo models and their calibration. In such situations, mathematical data assimilation methods provide an optimal approach for combining the available observational data and their uncertainties with theoretical models in order to estimate the state of the solar dynamo and predict future cycles. In this presentation, we will discuss the implementation and performance of an Ensemble Kalman Filter data assimilation method based on the Parker migratory dynamo model, complemented by the equation of magnetic helicity conservation and long-term sunspot data series. This approach has allowed us to reproduce the general properties of solar cycles and has already demonstrated a good predictive capability for the current cycle, 24. We will discuss further development of this approach, which includes a more sophisticated dynamo model, synoptic magnetogram data, and employs the DART Data Assimilation Research Testbed.

A GCM Recent History of Northern Martian Polar Layered Deposits: Contribution from Past Equatorial Ice Reservoirs

NASA Technical Reports Server (NTRS)

Levrard, B.; Laskar, J.; Montmessin, F.; Forget, F.

2005-01-01

Polar layered deposits are exposed in the walls of the troughs cutting the north polar cap of Mars. They consist of alternating ice and dust layers or layers of an ice-dust mixture with varying proportions and are found throughout the cap. Layers thickness ranges from meters to several tens of meters with an approximately 30 meter dominant wavelength. Although their formation processes is not known, they are presumed to reflect changes in ice and dust stability over orbital and axial variations. Intensive 3-D LMD GCM simulations of the martian water cycle have been thus performed to determine the annual rates of exchange of surface ice between the northern cap and tropical areas for a wide range of obliquity and orbital parameters values.These rates have been employed to reconstruct an history of the northern cap and test simple models of dust-ice layers formation over the last 10 Ma orbital variations. We use the 3-D water cycle model simulated by the 3-D LMD GCM with an intermediate grid resolution (7.5 longitude x 5.625 latitude) and 25 vertical levels. The dust opacity is constant and set to 0,15. No exchange of ice with regolith is allowed. The evolution of the northern cap over obliquity and orbital changes (eccentricity, Longitude of perihelion) has been recently described with this model. High summer insolation favors transfer of ice from the northern pole to the Tharsis and Olympus Montes, while at low obliquity, unstable equatorial ice is redeposited in high-latitude and polar areas of both hemisphere. The disappearance of the equatorial ice reservoir leads to a poleward recession of icy high latitude reservoirs, providing an additional source for the cap accumulation during each obliquity or orbital cycle. Furthering the efforts, a quantitative evolution of ice reservoirs is here investigated for various astronomical conditions.

Updated greenhouse gas and criteria air pollutant emission factors and their probability distribution functions for electricity generating units

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, H.; Wang, M.; Elgowainy, A.

Greenhouse gas (CO{sub 2}, CH{sub 4} and N{sub 2}O, hereinafter GHG) and criteria air pollutant (CO, NO{sub x}, VOC, PM{sub 10}, PM{sub 2.5} and SO{sub x}, hereinafter CAP) emission factors for various types of power plants burning various fuels with different technologies are important upstream parameters for estimating life-cycle emissions associated with alternative vehicle/fuel systems in the transportation sector, especially electric vehicles. The emission factors are typically expressed in grams of GHG or CAP per kWh of electricity generated by a specific power generation technology. This document describes our approach for updating and expanding GHG and CAP emission factors inmore » the GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model developed at Argonne National Laboratory (see Wang 1999 and the GREET website at http://greet.es.anl.gov/main) for various power generation technologies. These GHG and CAP emissions are used to estimate the impact of electricity use by stationary and transportation applications on their fuel-cycle emissions. The electricity generation mixes and the fuel shares attributable to various combustion technologies at the national, regional and state levels are also updated in this document. The energy conversion efficiencies of electric generating units (EGUs) by fuel type and combustion technology are calculated on the basis of the lower heating values of each fuel, to be consistent with the basis used in GREET for transportation fuels. On the basis of the updated GHG and CAP emission factors and energy efficiencies of EGUs, the probability distribution functions (PDFs), which are functions that describe the relative likelihood for the emission factors and energy efficiencies as random variables to take on a given value by the integral of their own probability distributions, are updated using best-fit statistical curves to characterize the uncertainties associated with GHG and CAP emissions in life-cycle modeling with GREET.« less

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 changes approach 8-9% in the Arctic lower mesosphere and lower stratosphere and 12% in the Antarctic lower stratosphere. These results point at an important role of atmospheric circulation in the response of the Earth atmosphere to the 11-year solar cycle.

Forecasting the peak of the present solar activity cycle 24

NASA Astrophysics Data System (ADS)

Hamid, R. H.; Marzouk, B. A.

2018-06-01

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 aamin. 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 maximum of solar cycles (RM) and spotless event around the preceding minimum gives R24t = 88.4 with rise time Tr = 4.6 years. For the even cycles R24E = 77.9 with rise time Tr = 4.5 y's. Based on the average aamin. index for cycles (12-23), we estimate the expected amplitude for cycle 24 to be Raamin = 99.4 and 98.1 with time rise of Traamin = 4.04 & 4.3 years for both the total and even cycles in consecutive. The 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 = 126 with rise time Tr107 = 3.7 years, which are over estimation. Our result indicating to somewhat weaker of cycle 24 as compared to cycles 21-23.

The Solar Wind Source Cycle: Relationship to Dynamo Behavior

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Li, Y.; Lee, C. O.; Jian, L. K.; Petrie, G. J. D.; Arge, C. N.

2017-12-01

Solar cycle trends of interest include the evolving properties of the solar wind, the heliospheric medium through which the Sun's plasmas and fields interact with Earth and the planets -including the evolution of CME/ICMEs enroute. Solar wind sources include the coronal holes-the open field regions that constantly evolve with solar magnetic fields as the cycle progresses, and the streamers between them. The recent cycle has been notably important in demonstrating that not all solar cycles are alike when it comes to contributions from these sources, including in the case of ecliptic solar wind. In particular, it has modified our appreciation of the low latitude coronal hole and streamer sources because of their relative prevalence. One way to understand the basic relationship between these source differences and what is happening inside the Sun and on its surface is to use observation-based models like the PFSS model to evaluate the evolution of the coronal field geometry. Although the accuracy of these models is compromised around solar maximum by lack of global surface field information and the sometimes non-potential evolution of the field related to more frequent and widespread emergence of active regions, they still approximate the character of the coronal field state. We use these models to compare the inferred recent cycle coronal holes and streamer belt sources of solar wind with past cycle counterparts. The results illustrate how (still) hemispherically asymmetric weak polar fields maintain a complex mix of low-to-mid latitude solar wind sources throughout the latest cycle, with a related marked asymmetry in the hemispheric distribution of the ecliptic wind sources. This is likely to be repeated until the polar field strength significantly increases relative to the fields at low latitudes, and the latter symmetrize.

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, rather than requiring an unexpected change in the physical behavior of the Sun.

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.

Spectral solar UV irradiance data for cycle 21

NASA Astrophysics Data System (ADS)

DeLand, Matthew T.; Cebula, Richard P.

2001-10-01

The Nimbus 7 Solar Backscatter Ultraviolet (SBUV) instrument, which began taking data in November 1978, was the first instrument to make solar UV irradiance measurements covering both the minimum and maximum activity levels of a solar cycle. The currently archived irradiance data set was processed with an instrument characterization which fails to completely account for sensor degradation in the later part of the data record, thus limiting the accuracy of estimated long-term solar activity variations and the scientific value of the data. In this paper, we describe an improved Nimbus 7 SBUV spectral irradiance data set, which utilizes a more accurate model for instrument sensitivity and treats other time-dependent problems in the archived data. Estimated long-term irradiance changes during solar cycle 21 are 8.3(+/-2.6%) at 205 nm, and 4.9(+/-1.8)% at 240 nm. The revised Nimbus 7 SBUV irradiance data are in good agreement with predictions of solar cycle variations from the Mg II index proxy model. These solar irradiance changes are also consistent with overlapping irradiance data from the declining phase of solar cycle 21 measured by the Solar Mesosphere Explorer (SME). The Nimbus 7 SBUV irradiance data represent the earliest component of a 20+ year continuous record of solar spectral UV activity.

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.

The Fraction of Interplanetary Coronal Mass Ejections That Are Magnetic Clouds: Evidence for a Solar Cycle Variation

NASA Technical Reports Server (NTRS)

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

2004-01-01

"Magnetic clouds" (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized by enhanced magnetic fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the solar wind. A comprehensive survey of ICMEs in the near- Earth solar wind during the ascending, maximum and early declining phases of solar cycle 23 in 1996 - 2003 shows that the MC fraction varies with the phase of the solar cycle, from approximately 100% (though with low statistics) at solar minimum to approximately 15% at solar maximum. A similar trend is evident in near-Earth observations during solar cycles 20 - 21, while Helios 1/2 spacecraft observations at 0.3 - 1.0 AU show a weaker trend and larger MC fraction.

CORONAL DYNAMIC ACTIVITIES IN THE DECLINING PHASE OF A SOLAR CYCLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2016-12-10

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 secondmore » 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.« less

Occurrence of ion upflow associated with ion/electron heating in the polar cap and cusp regions

NASA Astrophysics Data System (ADS)

Ji, E. Y.; Jee, G.; Kwak, Y. S.

2017-12-01

We investigate the occurrence frequency of ion upflow in association with ion/electron heating in the polar cap and cusp regions, using the data obtained from the European Incoherent Scatter Svalbard radar (ESR) during the period of 2000 to 2010. We classify the upflow events by four cases: driven by ion heating (case 1), electron heating (case 2), both ion and electron heatings (case 3), and without any heating (case 4). The statistical analysis of the data shows that the upflow normaly starts at around 350 km altitude and the occurrence seems to peak at 11 MLT. Among the four cases, the occurrence frequency of the upflow is maximized for the case 3 and then followed by case 2, case 1 and case 3, which indicates that both ion and electron heatings are associated with ion upflow. At around 500 km altitude, however, the occurrence frequency is maximized when there is no heating (case 4). We also investigate the dependence of the occurrence frequency of the upflow on Kp and F10.7 indices. The maximum occurrence frequency seems to occur at moderate geomagnetic condition (2 ≤ Kp < 5). As for the solar activity, the occurrence frequency is higher for low solar activity than for high solar activity. The results of this study suggest that the ion upflow occurring in the polar cap/cusp region is mostly driven by both ion and electron heatings.

OBSERVATIONS AND MODELING OF NORTH-SOUTH ASYMMETRIES USING A FLUX TRANSPORT DYNAMO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shetye, Juie; Tripathi, Durgesh; Dikpati, Mausumi

2015-02-01

The peculiar behavior of solar cycle 23 and its prolonged minima has been one of the most studied problems over the past few years. In the present paper, we study the asymmetries in active region magnetic flux in the northern and southern hemispheres during the complete solar cycle 23 and the rising phase of solar cycle 24. During the declining phase of solar cycle 23, we find that the magnetic flux in the southern hemisphere is about 10 times stronger than that in the northern hemisphere; however, during the rising phase of cycle 24, this trend is reversed. The magnetic fluxmore » becomes about a factor of four stronger in the northern hemisphere than in the southern hemisphere. Additionally, we find that there was a significant delay (about five months) in change of the polarity in the southern hemisphere in comparison with the northern hemisphere. These results provide us with hints of how the toroidal fluxes have contributed to the solar dynamo during the prolonged minima in solar cycle 23 and in the rising phase of solar cycle 24. Using a solar flux-transport dynamo model, we demonstrate that persistently stronger sunspot cycles in one hemisphere could be caused by the effect of greater inflows into active region belts in that hemisphere. Observations indicate that greater inflows are associated with stronger activity. Some other change or difference in meridional circulation between hemispheres could cause the weaker hemisphere to become the stronger one.« less

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.

Apparent Relations Between Solar Activity and Solar Tides Caused by the Planets

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh

2007-01-01

A solar storm is a storm of ions and electrons from the Sun. Large solar storms are usually preceded by solar flares, phenomena that can be characterized quantitatively from Earth. Twenty-five of the thirty-eight largest known solar flares were observed to start when one or more tide-producing planets (Mercury, Venus, Earth, and Jupiter) were either nearly above the event positions (less than 10 deg. longitude) or at the opposing side of the Sun. The probability for this to happen at random is 0.039 percent. This supports the hypothesis that the force or momentum balance (between the solar atmospheric pressure, the gravity field, and magnetic field) on plasma in the looping magnetic field lines in solar corona could be disturbed by tides, resulting in magnetic field reconnection, solar flares, and solar storms. Separately, from the daily position data of Venus, Earth, and Jupiter, an 11-year planet alignment cycle is observed to approximately match the sunspot cycle. This observation supports the hypothesis that the resonance and beat between the solar tide cycle and nontidal solar activity cycle influences the sunspot cycle and its varying magnitudes. The above relations between the unpredictable solar flares and the predictable solar tidal effects could be used and further developed to forecast the dangerous space weather and therefore reduce its destructive power against the humans in space and satellites controlling mobile phones and global positioning satellite (GPS) systems.

Landscape evolution on Mars - A model of aeolian denudation in Gale Crater

NASA Astrophysics Data System (ADS)

Day, M. D.; Kocurek, G.; Grotzinger, J. P.

2015-12-01

Aeolian erosion has been the dominant geomorphic agent to shape the surface of Mars for the past ~3.5 billion years. Although individual geomorphic features evidencing aeolian activity are well understood (e.g., yardangs, dune fields, and wind streaks), landscapes formed by aeolian erosion remain poorly characterized. Intra-crater sedimentary mounds are hypothesized to have formed by wind deflation of craters once filled with flat-lying strata, and, therefore, should be surrounded by landscapes formed by aeolian erosion. Here we present a landscape evolution model that provides both an initial characterization of aeolian landscapes, and a mechanism for large-scale excavation. Wind excavation of Gale Crater to form the 5 km high Mount Sharp would require removal of 6.4 x 104 km3 of sediment. Imagery in Gale Crater from satellites and the Mars Science Laboratory rover Curiosity shows a surface characterized by first-cycle aeolian erosion of bedrock. The overall landscape is interpreted to represent stages in a cycle of aeolian deflation and excavation, enhanced by physical weathering (e.g., thermal fracturing, cratering). Initial wind erosion of bedrock is enhanced along fractures, producing retreating scarps. Underlying less resistant layers then erode faster than the armoring cap rock, increasing relief in scarps to form retreating mesas. As scarp retreat continues, boulders from the armoring cap unit break away and cover the hillslopes of less resistant material below the scarps. Eventually all material from the capping unit is eroded away and a boulder-capped hill remains. Winnowing of fine material flattens hillslope topography, leaving behind a desert pavement. Over long enough time, this pavement is breached and the cycle begins anew. This cycle of landscape denudation by the wind is similar to that of water, but lacks characteristic subaqueous features such as dendritic drainage networks.

Solar cycle modulation of Southern Annular Mode -Energy-momentum analysis-

NASA Astrophysics Data System (ADS)

Kuroda, Y.

2016-12-01

Climate is 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 Southern Annular Mode (SAM) in late-winter/spring show structural modulation associated with 11-year solar cycle. In fact, SAM-related signal tends to extend from surface to upper stratosphere and persistent longer period in the High Solar (HS) years, whereas it is restricted in the troposphere and not persist in the Low Solar (LS) 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.

Decoupling Solar Variability and Instrument Trends Using the Multiple Same-Irradiance-Level (MuSIL) Analysis Technique

NASA Astrophysics Data System (ADS)

Woods, Thomas N.; Eparvier, Francis G.; Harder, Jerald; Snow, Martin

2018-05-01

The solar spectral irradiance (SSI) dataset is a key record for studying and understanding the energetics and radiation balance in Earth's environment. Understanding the long-term variations of the SSI over timescales of the 11-year solar activity cycle and longer is critical for many Sun-Earth research topics. Satellite measurements of the SSI have been made since the 1970s, most of them in the ultraviolet, but recently also in the visible and near-infrared. A limiting factor for the accuracy of previous solar variability results is the uncertainties for the instrument degradation corrections, which need fairly large corrections relative to the amount of solar cycle variability at some wavelengths. The primary objective of this investigation has been to separate out solar cycle variability and any residual uncorrected instrumental trends in the SSI measurements from the Solar Radiation and Climate Experiment (SORCE) mission and the Thermosphere, Mesosphere, Ionosphere, Energetic, and Dynamics (TIMED) mission. A new technique called the Multiple Same-Irradiance-Level (MuSIL) analysis has been developed, which examines an SSI time series at different levels of solar activity to provide long-term trends in an SSI record, and the most common result is a downward trend that most likely stems from uncorrected instrument degradation. This technique has been applied to each wavelength in the SSI records from SORCE (2003 - present) and TIMED (2002 - present) to provide new solar cycle variability results between 27 nm and 1600 nm with a resolution of about 1 nm at most wavelengths. This technique, which was validated with the highly accurate total solar irradiance (TSI) record, has an estimated relative uncertainty of about 5% of the measured solar cycle variability. The MuSIL results are further validated with the comparison of the new solar cycle variability results from different solar cycles.

Mid-Term Quasi-Periodicities and Solar Cycle Variation of the White-Light Corona from 18.5 Years (1996.0 - 2014.5) of LASCO Observations

NASA Astrophysics Data System (ADS)

Barlyaeva, T.; Lamy, P.; Llebaria, A.

2015-07-01

We report on the analysis of the temporal evolution of the solar corona based on 18.5 years (1996.0 - 2014.5) of white-light observations with the SOHO/LASCO-C2 coronagraph. This evolution is quantified by generating spatially integrated values of the K-corona radiance, first globally, then in latitudinal sectors. The analysis considers time series of monthly values and 13-month running means of the radiance as well as several indices and proxies of solar activity. We study correlation, wavelet time-frequency spectra, and cross-coherence and phase spectra between these quantities. Our results give a detailed insight on how the corona responds to solar activity over timescales ranging from mid-term quasi-periodicities (also known as quasi-biennial oscillations or QBOs) to the long-term 11 year solar cycle. The amplitude of the variation between successive solar maxima and minima (modulation factor) very much depends upon the strength of the cycle and upon the heliographic latitude. An asymmetry is observed during the ascending phase of Solar Cycle 24, prominently in the royal and polar sectors, with north leading. Most prominent QBOs are a quasi-annual period during the maximum phase of Solar Cycle 23 and a shorter period, seven to eight months, in the ascending and maximum phases of Solar Cycle 24. They share the same properties as the solar QBOs: variable periodicity, intermittency, asymmetric development in the northern and southern solar hemispheres, and largest amplitudes during the maximum phase of solar cycles. The strongest correlation of the temporal variations of the coronal radiance - and consequently the coronal electron density - is found with the total magnetic flux. Considering that the morphology of the solar corona is also directly controlled by the topology of the magnetic field, this correlation reinforces the view that they are intimately connected, including their variability at all timescales.

Variability of the martian seasonal CO2 cap extent over eight Mars Years

NASA Astrophysics Data System (ADS)

Piqueux, Sylvain; Kleinböhl, Armin; Hayne, Paul O.; Kass, David M.; Schofield, John T.; McCleese, Daniel J.

2015-05-01

We present eight Mars Years of nearly continuous tracking of the CO2 seasonal cap edges from Mars Year (MY) 24 to 31 using Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) and Mars Reconnaissance Orbiter (MRO) Mars Climate Sounder (MCS) thermal infrared data. Spatial and temporal resolutions are 1 pixel per degree and 10°Ls (aerocentric longitude of the Sun). The seasonal caps are defined as the regions where the diurnal radiometric temperature variations at ∼32 μm wavelength do not exceed 5 K. With this definition, terrains with small areal fraction of defrosted regolith able to experience measurable diurnal temperature cycles are not mapped as part of the cap. This technique is adequate to distinguish CO2 from H2O ices, and effective during the polar night or under low illumination conditions. The present analysis answers outstanding questions stemming from fragmented observations at visible wavelengths: (1) the previously sparsely documented growth of the North seasonal caps (160° < Ls < 270°) is shown to be repeatable within 1-2° equivalent latitude, and monotonic over the MY 24-31 time period; high repeatability is observed during the retreat of the caps in non-dusty years (∼1° or less equivalent latitude); (2) the MY 25 storm does not seem to have impacted the growth rate, maximal extents, or recession rate of the North seasonal caps, whereas the MY 28 dust storm clearly sped up the recession of the cap (∼2° smaller on average after the storm, during the recession, compared to other years); (3) during non-dusty years, the growth of the South seasonal cap (350° < Ls < 100°) presents noticeable variability (up to ∼4° equivalent latitude near Ls = 20°) with a maximum extent reached near Ls = 90°; (4) the retreat of the Southern seasonal cap (100° < Ls < 310°) exhibits large inter-annual variability, especially near 190° < Ls < 220°; (5) the recession of the MY 25 South seasonal cap is significantly accelerated during the equinox global dust storm, with surface temperatures suggesting increased patchiness or enhanced dust mantling on the CO2 ice. These results suggest that atmospheric temperatures and dust loading are the primary source of variability in an otherwise remarkably repeatable cycle of seasonal cap growth and recession.

Monitoring Auroral Electrojet from Polar Cap Stations

NASA Astrophysics Data System (ADS)

Tan, A.; Lyatsky, W.; Lyatskaya, S.

2004-12-01

The auroral electrojet AL and AE geomagnetic activity indices are important for monitoring geomagnetic substorms. In the northern hemisphere these indices are derived from measurements at a set of geomagnetic observatories located in the auroral zone. In the southern hemisphere the major portion of the auroral zone is located on the ocean; this does not allow us to derive the auroral electrojet indices in the same way. We showed that monitoring the auroral electrojet is possible from magnetic field measurements at polar cap stations. For this purpose we used hourly values of geomagnetic field variations at four polar cap stations, distributed along polar cap boundary and occupying a longitudinal sector of about 14 hours, and calculated mean values of the total magnetic field disturbance T = (X2 + Y2 + Z2)1/2 where X, Y, and Z are geomagnetic field components measured at these polar cap stations. The set of the obtained values were called the T index. This index has a clear physical mining: it is the summary of geomagnetic disturbance in all three components averaged over the polar cap boundary. We found that correlation coefficients for the dependence of the T index on both AL and AE indices are as high as ~0.9 and higher. The high correlation of the T index with the AL and AE indices takes place for any UT hour when the stations were located at the night side. The T index further shows good correlation with solar wind parameters: the correlation coefficient for the dependence of the T index on the solar wind-geomagnetic activity coupling function is ~0.8 and higher, which is close to the correlation coefficient for AL index. The T index may be especially important in the cases when ground-based measurements in the auroral zone are impossible as in the southern hemisphere.

Simulated Effect of Carbon Cycle Feedback on Climate Response to Solar Geoengineering

NASA Astrophysics Data System (ADS)

Cao, Long; Jiang, Jiu

2017-12-01

Most modeling studies investigate climate effects of solar geoengineering under prescribed atmospheric CO2, thereby neglecting potential climate feedbacks from the carbon cycle. Here we use an Earth system model to investigate interactive feedbacks between solar geoengineering, global carbon cycle, and climate change. We design idealized sunshade geoengineering simulations to prevent global warming from exceeding 2°C above preindustrial under a CO2 emission scenario with emission mitigation starting from middle of century. By year 2100, solar geoengineering reduces the burden of atmospheric CO2 by 47 PgC with enhanced carbon storage in the terrestrial biosphere. As a result of reduced atmospheric CO2, consideration of the carbon cycle feedback reduces required insolation reduction in 2100 from 2.0 to 1.7 W m-2. With higher climate sensitivity the effect from carbon cycle feedback becomes more important. Our study demonstrates the importance of carbon cycle feedback in climate response to solar geoengineering.

Glucose capped silver nanoparticles induce cell cycle arrest in HeLa cells.

PubMed

Panzarini, Elisa; Mariano, Stefania; Vergallo, Cristian; Carata, Elisabetta; Fimia, Gian Maria; Mura, Francesco; Rossi, Marco; Vergaro, Viviana; Ciccarella, Giuseppe; Corazzari, Marco; Dini, Luciana

2017-06-01

This study aims to determine the interaction (uptake and biological effects on cell viability and cell cycle progression) of glucose capped silver nanoparticles (AgNPs-G) on human epithelioid cervix carcinoma (HeLa) cells, in relation to amount, 2×10 3 or 2×10 4 NPs/cell, and exposure time, up to 48h. The spherical and well dispersed AgNPs (30±5nm) were obtained by using glucose as reducing agent in a green synthesis method that ensures to stabilize AgNPs avoiding cytotoxic soluble silver ions Ag + release. HeLa cells take up abundantly and rapidly AgNPs-G resulting toxic to cells in amount and incubation time dependent manner. HeLa cells were arrested at S and G2/M phases of the cell cycle and subG1 population increased when incubated with 2×10 4 AgNPs-G/cell. Mitotic index decreased accordingly. The dissolution experiments demonstrated that the observed effects were due only to AgNPs-G since glucose capping prevents Ag + release. The AgNPs-G influence on HeLa cells viability and cell cycle progression suggest that AgNPs-G, alone or in combination with chemotherapeutics, may be exploited for the development of novel antiproliferative treatment in cancer therapy. However, the possible influence of the cell cycle on cellular uptake of AgNPs-G and the mechanism of AgNPs entry in cells need further investigation. Copyright © 2017 Elsevier B.V. All rights reserved.

Energetic Charged Particle Component or the NO(y) Budget of the Polar Middle Atmosphere

NASA Technical Reports Server (NTRS)

Vitt, F. M.; Jackman, C. H.

1999-01-01

Analysis of nitrates measured in polar ice cap snow at a high resolution shows large variations in the nitrates. It has been shown that the nitrate signal may contain a signature of solar activity [Zeller and Dreschhoff, 19951. Reactive odd nitrogen production associated with solar particle events (SPEs) and auroral activity may be a source of some of the nitrate anomalies observed in the polar ice caps. Periods of large SPEs can lead to a production of polar atmospheric odd nitrogen in excess of the ambient sources in the polar stratosphere and mesosphere, and may leave a large nitrate signal stratified in the polar ice cap. Auroral electrons and photoelectrons produce odd nitrogen in the thermosphere, some of which may be transported to the polar (>50 degrees) mesosphere and stratosphere. Sources of odd nitrogen in the polar middle atmosphere associated with SPEs, galactic cosmic rays, and auroral electron precipitation have been quantified. The relative contributions by the energetic particles sources to the Noy budget of the polar middle atmosphere (from tropopause to 50 km, from 50 degrees to 90 degrees latitude) are compared with the nitrates observed in the polar ice sheets.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munoz-Jaramillo, Andres; DeLuca, Edward E.; Dasi-Espuig, Maria

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 databasesmore » 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.« less

Stochastic Fluctuations in a Babcock-Leighton Model of the Solar Cycle

NASA Astrophysics Data System (ADS)

Charbonneau, Paul; Dikpati, Mausumi

2000-11-01

We investigate the effect of stochastic fluctuations on a flux transport model of the solar cycle based on the Babcock-Leighton mechanism. Specifically, we make use of our recent flux transport model (Dikpati & Charbonneau) to investigate the consequences of introducing large-amplitude stochastic fluctuations in either or both the meridional flow and poloidal source term in the model. Solar cycle-like oscillatory behavior persists even for fluctuation amplitudes as high as 300%, thus demonstrating the inherent robustness of this class of solar cycle models. We also find that high-amplitude fluctuations lead to a spread of cycle amplitude and duration showing a statistically significant anticorrelation, comparable to that observed in sunspot data. This is a feature of the solar cycle that is notoriously difficult to reproduce with dynamo models based on mean field electrodynamics and relying only on nonlinearities associated with the back-reaction of the Lorentz force to produce amplitude modulation. Another noteworthy aspect of our flux transport model is the fact that meridional circulation in the convective envelope acts as a ``clock'' regulating the tempo of the solar cycle; shorter-than-average cycles are typically soon followed by longer-than-average cycles. In other words, the oscillation exhibits good phase locking, a property that also characterizes the solar activity cycle. This shows up quite clearly in our model, but we argue that it is in fact a generic property of flux transport models based on the Babcock-Leighton mechanism, and relies on meridional circulation as the primary magnetic field transport agent.

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.

Phase space representation of neutron monitor count rate and atmospheric electric field in relation to solar activity in cycles 21 and 22.

PubMed

Silva, H G; Lopes, I

Heliospheric modulation of galactic cosmic rays links solar cycle activity with neutron monitor count rate on earth. A less direct relation holds between neutron monitor count rate and atmospheric electric field because different atmospheric processes, including fluctuations in the ionosphere, are involved. Although a full quantitative model is still lacking, this link is supported by solid statistical evidence. Thus, a connection between the solar cycle activity and atmospheric electric field is expected. To gain a deeper insight into these relations, sunspot area (NOAA, USA), neutron monitor count rate (Climax, Colorado, USA), and atmospheric electric field (Lisbon, Portugal) are presented here in a phase space representation. The period considered covers two solar cycles (21, 22) and extends from 1978 to 1990. Two solar maxima were observed in this dataset, one in 1979 and another in 1989, as well as one solar minimum in 1986. Two main observations of the present study were: (1) similar short-term topological features of the phase space representations of the three variables, (2) a long-term phase space radius synchronization between the solar cycle activity, neutron monitor count rate, and potential gradient (confirmed by absolute correlation values above ~0.8). Finally, the methodology proposed here can be used for obtaining the relations between other atmospheric parameters (e.g., solar radiation) and solar cycle activity.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebert, R. W.; Dayeh, M. A.; Desai, M. I.

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 betweenmore » {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.« less

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.

The effects of solarization on the performance of a gas turbine

NASA Astrophysics Data System (ADS)

Homann, Christiaan; van der Spuy, Johan; von Backström, Theodor

2016-05-01

Various hybrid solar gas turbine configurations exist. The Stellenbosch University Solar Power Thermodynamic (SUNSPOT) cycle consists of a heliostat field, solar receiver, primary Brayton gas turbine cycle, thermal storage and secondary Rankine steam cycle. This study investigates the effect of the solarization of a gas turbine on its performance and details the integration of a gas turbine into a solar power plant. A Rover 1S60 gas turbine was modelled in Flownex, a thermal-fluid system simulation and design code, and validated against a one-dimensional thermodynamic model at design input conditions. The performance map of a newly designed centrifugal compressor was created and implemented in Flownex. The effect of the improved compressor on the performance of the gas turbine was evident. The gas turbine cycle was expanded to incorporate different components of a CSP plant, such as a solar receiver and heliostat field. The solarized gas turbine model simulates the gas turbine performance when subjected to a typical variation in solar resource. Site conditions at the Helio100 solar field were investigated and the possibility of integrating a gas turbine within this system evaluated. Heat addition due to solar irradiation resulted in a decreased fuel consumption rate. The influence of the additional pressure drop over the solar receiver was evident as it leads to decreased net power output. The new compressor increased the overall performance of the gas turbine and compensated for pressure losses incurred by the addition of solar components. The simulated integration of the solarized gas turbine at Helio100 showed potential, although the solar irradiation is too little to run the gas turbine on solar heat alone. The simulation evaluates the feasibility of solarizing a gas turbine and predicts plant performance for such a turbine cycle.

Terminator 2020: Get Ready for the "Event" of The Next Decade

NASA Astrophysics Data System (ADS)

McIntosh, S. W.; Leamon, R. J.; Fan, Y.; Rempel, M.; Dikpati, M.

2017-12-01

The abrupt end of solar activity cycles 22 and 23 at the Sun's equator are observed with instruments from the Solar and Heliospheric Observatory (SOHO), Solar Terrestrial Relations Observatory (STEREO), and Solar Dynamics Observatory (SDO). These events are remarkable in that they rapidly trigger the onset of magnetic activity belonging to the next solar cycle at mid-latitudes. The triggered onset of new cycle flux emergence leads to blossoming of the new cycle shortly thereafter. Using small-scale tracers of magnetic solar activity we examine the timing of the cycle ``termination points'' in relation to the excitation of new activity and find that the time taken for the solar plasma to communicate this transition is less than one solar rotation, and possibly as little as a eight days. This very short transition time implies that the mean magnetic field present in the Sun's convection zone is approximately 80 kG. This value may be considerably larger than conventional explorations estimate and therefore, have a significant dynamical impact on the physical appearance of solar activity, and considerably impacting our ability to perform first-principles numerical simulations of the same. Should solar cycle 24 [and 25] continue in their progression we anticipate that a termination event of this type should occur in the 2020 timeframe. PSP will have a front row seat to observe this systemic flip in solar magnetism and the induced changes in our star's radiative and partiuculate output. Such observations may prove to be critical in assessing the Sun's ability to force short term evolution in the Earth's atmosphere.

Solar cycle variations in mesospheric carbon monoxide

NASA Astrophysics Data System (ADS)

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

2018-05-01

As an extension of Lee et al. (2013), solar cycle variation of carbon monoxide (CO) is analyzed with MLS observation, which covers more than thirteen years (2004-2017) including maximum of solar cycle 24. Being produced primarily by the carbon dioxide (CO2) photolysis in the lower thermosphere, the variations of the mesospheric CO concentration are largely driven by the solar cycle modulated ultraviolet (UV) variation. This solar signal extends down to the lower altitudes by the dynamical descent in the winter polar vortex, showing a time lag that is consistent with the average descent velocity. To characterize a global distribution of the solar impact, MLS CO is correlated with the SORCE measured total solar irradiance (TSI) and UV. As high as 0.8 in most of the polar mesosphere, the linear correlation coefficients between CO and UV/TSI are more robust than those found in the previous work. The photochemical contribution explains most (68%) of the total variance of CO while the dynamical contribution accounts for 21% of the total variance at upper mesosphere. The photochemistry driven CO anomaly signal is extended in the tropics by vertical mixing. The solar cycle signal in CO is further examined with the Whole Atmosphere Community Climate Model (WACCM) 3.5 simulation by implementing two different modeled Spectral Solar Irradiances (SSIs): SRPM 2012 and NRLSSI. The model simulations underestimate the mean CO amount and solar cycle variations of CO, by a factor of 3, compared to those obtained from MLS observation. Different inputs of the solar spectrum have small impacts on CO variation.

Lagged correlations between the NAO and the 11-year solar cycle: forced response or internal variability?

NASA Astrophysics Data System (ADS)

Oehrlein, J.; Chiodo, G.; Polvani, L. M.; Smith, A. K.

2017-12-01

Recently, the North Atlantic Oscillation has been suggested to respond to the 11-year solar cycle with a lag of a few years. The solar/NAO relationship provides a potential pathway for solar activity to modulate surface climate. However, a short observational record paired with the strong internal variability of the NAO raises questions about the robustness of the claimed solar/NAO relationship. For the first time, we investigate the robustness of the solar/NAO signal in four different reanalysis data sets and long integrations from an ocean-coupled chemistry-climate model forced with the 11-year solar cycle. The signal appears to be robust in the different reanalysis datasets. We also show, for the first time, that many features of the observed signal, such as amplitude, spatial pattern, and lag of 2/3 years, can be accurately reproduced in our model simulations. However, in both the reanalysis and model simulations, we find that this signal is non-stationary. A lagged NAO/solar signal can also be reproduced in two sets of model integrations without the 11-year solar cycle. This suggests that the correlation found in observational data could be the result of internal decadal variability in the NAO and not a response to the solar cycle. This has wide implications towards the interpretation of solar signals in observational data.

How unprecedented a solar minimum was it?

PubMed

Russell, C T; Jian, L K; Luhmann, J G

2013-05-01

The end of the last solar cycle was at least 3 years late, and to date, the new solar cycle has seen mainly weaker activity since the onset of the rising phase toward the new solar maximum. The newspapers now even report when auroras are seen in Norway. This paper is an update of our review paper written during the deepest part of the last solar minimum [1]. We update the records of solar activity and its consequent effects on the interplanetary fields and solar wind density. The arrival of solar minimum allows us to use two techniques that predict sunspot maximum from readings obtained at solar minimum. It is clear that the Sun is still behaving strangely compared to the last few solar minima even though we are well beyond the minimum phase of the cycle 23-24 transition.

Solar cycle variability of nonmigrating tides in the infrared cooling of the thermosphere

NASA Astrophysics Data System (ADS)

Nischal, N.; Oberheide, J.; Mlynczak, M. G.; Marsh, D. R.

2017-12-01

Nitric Oxide (NO) at 5.3 μm and Carbon dioxide (CO2) at 15 μm are the major infrared emissions responsible for the radiative cooling of the thermosphere. We study the impact of two important diurnal nonmigrating tides, the DE2 and DE3, on NO and CO2 infrared emissions over a complete solar cycle (2002-2013) by (i) analyzing NO and CO2 cooling rate data from SABER and (ii) photochemical modeling using dynamical tides from a thermospheric empirical tidal model, CTMT. Both observed and modeled results show that the NO cooling rate amplitudes for DE2 and DE3 exhibit strong solar cycle dependence. NO 5.3 μm cooling rate tides are relatively unimportant for the infrared energy budget during solar minimum but important during solar maximum. On the other hand DE2 and DE3 in CO2 show comparatively small variability over a solar cycle. CO2 15 μm cooling rate tides remain, to a large extent, constant between solar minimum and maximum. This different responses by NO and CO2 emissions to the DE2 and DE3 during a solar cycle comes form the fact that the collisional reaction rate for NO is highly sensitive to the temperature comparative to that for CO2. Moreover, the solar cycle variability of these nonmigrating tides in thermospheric infrared emissions shows a clear QBO signals substantiating the impact of tropospheric weather system on the energy budget of the thermosphere. The relative contribution from the individual tidal drivers; temperature, density and advection to the observed DE2 and DE3 tides does not vary much over the course of the solar cycle, and this is true for both NO and CO2 emissions.

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.

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.

High-Latitude Ionospheric Imaging using Canadian High Arctic Ionospheric Network (CHAIN)

NASA Astrophysics Data System (ADS)

Meziane, K.; Jayachandran, P. T.; Hamza, A. M.; MacDougall, J. W.

2013-12-01

Understanding the polar cap dynamics is a fundamental problem in solar-terrestrial physics; any breakthroughs would have to take into account the interactions that take place at the interfaces between the Solar Wind and the Magnetosphere and between the latter and the ionosphere, respectively. Over the past decade a significant number of ground-based GPS receivers and digital ionosondes have been deployed in the polar cap and auroral region. This deployment has allowed the harvest of much needed data, otherwise not available, which in turn helps understand the dynamics of the polar ionospheric regions. A technique, used consistently by researchers in the field, consists of inverting the Total Electron Content (TEC) along the ray path obtained from a system of GPS receivers. In the present study, a combination of tomography and ionosonde data from the CHAIN network is used to examine the dynamics of polar cap patches. First, the TEC derived from GPS receivers through tomographic reconstruction is directly compared with ionosonde data. The comparison includes periods of quite and disturbed geomagnetic activity. We then use the vertical density profiles derived from the CHAIN ionosondes as initial seeds for the reconstruction of the tomographic images of the polar cap regions. Precise electron density peaks obtained through the tomographic reconstruction fall within a range that is consistent with direct CHAIN measurements when certain conditions are met. An assessment of the performance of the resulting combination of GPS and ionosonde data is performed, and conclusions are presented.

Orbitally-Induced, Quasi-Periodic Climate Change on Mars: Modelling Changes in the Global Cycling of Water and Carbon Dioxide

NASA Astrophysics Data System (ADS)

Mischna, M. A.; Richardson, M. I.; Wilson, R. J.

2002-12-01

Mars' orbital parameters (obliquity, eccentricity and argument of perihelion) are thought to have varied substantially on time scales >105 years. Such variations, especially in obliquity, may drastically affect the circulation of the atmosphere and volatile cycling. In this study, we focus on the response of the water and carbon dioxide cycles to changes in these orbital parameters, chiefly obliquity. The study employs the Geophysical Fluid Dynamics Laboratory Mars General Circulation Model, conducting simulations over a range of orbital states to examine changes in the cycling and deposition of these volatiles. This model contains full 3D accounting of atmospheric water and carbon dioxide as well as a basic dust cycle. The present martian obliquity is 25°, though it is believed to have recently varied between 15 and 45 degrees. Our simulations look at present martian conditions, only with obliquity varying between 5 and 60 degrees. Simulations are run out until water and carbon dioxide budgets have reached equilibrium--typically 30-40 years. As expected, volatile cycling on Mars increases with obliquity, as the polar caps are exposed to increased insolation, leading to greater seasonal ice caps and ultimately development of surface water ice in the now thermally favorible low latitudes. By 45°, water ice is stable in a broad band just north of the equator. Such an ice distribution has potential implications for the surface wind pattern through the ice-albedo effect on surface heating. Permanent polar CO2 caps are not stable under present conditions, but we find CO2 cap growth and corresponding atmospheric deflation to be evident at very low obliquities. We find that for most choices of orbital conditions, the northern hemisphere remains the stable pole for water ice, a result of the martian topographic dichotomy. We have begun to look at the impact of desorbed CO2 and H2O ice from the regolith on climatic conditions. Present estimates of the volatile abundance in the regolith vary greatly, but recent Mars Odyssey results hint at large abundances of water ice in the martian high-latitude regolith. The results of this study should better define models of polar volatile evolution, specifically those of layered terrain formation. The radiative feedback effects of increased atmospheric CO2 and H2O from the polar caps and regoliths has yet to be examined. Future plans include more accurate representations of dust injection and radiative transfer to tackle this problem.

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

NASA Astrophysics Data System (ADS)

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

2017-06-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, J. L.; Shi, X. J.; Xu, J. C., E-mail: xiejinglan@ynao.ac.cn

Based on continuous wavelet transformation analysis, the daily solar mean magnetic field (SMMF) from 1975 May 16 to 2014 July 31 is analyzed to reveal its rotational behavior. Both the recurrent plot in Bartels form and the continuous wavelet transformation analysis show the existence of rotational modulation in the variation of the daily SMMF. The dependence of the rotational cycle lengths on solar cycle phase is also studied, which indicates that the yearly mean rotational cycle lengths generally seem to be longer during the rising phase of solar cycles and shorter during the declining phase. The mean rotational cycle lengthmore » for the rising phase of all of the solar cycles in the considered time is 28.28 ± 0.67 days, while for the declining phase it is 27.32 ± 0.64 days. The difference of the mean rotational cycle lengths between the rising phase and the declining phase is 0.96 days. The periodicity analysis, through the use of an auto-correlation function, indicates that the rotational cycle lengths have a significant period of about 10.1 years. Furthermore, the cross-correlation analysis indicates that there exists a phase difference between the rotational cycle lengths and solar activity.« less

Curriculum Alignment Projects: Toward Developing a Need to Know

NASA Astrophysics Data System (ADS)

Pinkerton, K. David

2001-02-01

This study investigated means of designing a high school chemistry curriculum. A Curriculum Alignment Project (CAP) was used to coordinate one semester (18 weeks) of activities. CAPs are long-term, multiple-approach design and construction projects that provide students a concrete task to accomplish, rather than an abstract theme to appreciate. Topics were selected for their potential contribution to students' success on the CAP, not because the topics were coming up next in a textbook. One particular CAP, Bicarbonate Squeeze Play, is described in detail. After one cycle of CAPs, student motivation began to change from extrinsic to intrinsic; achievement on objective measures was holding steady; students' abilities to craft and carry out long-term plans for complex projects were improving; and the teacher was learning how to design curriculum that fostered students' need to know.

A model for polar cap electric fields

NASA Technical Reports Server (NTRS)

Dangelo, N.

1976-01-01

A model is proposed relating polar cap ionospheric electric fields to the parameters of the solar wind near the orbit of the earth. The model ignores the notion of field line merging. An essential feature is the role played by velocity shear instabilities in regions of the outer magnetosphere, in which mapping of the magnetosheath electric field would produce sunward convection. The anomalous resistivity which arises from velocity shear turbulence, suffices to essentially disconnect the magnetosphere from the magnetosheath, at any place where that resistivity is large enough. The magnetosheath-magnetosphere system, as a consequence, acts as a kind of diode or rectifier for the magnetosheath electric fields. Predictions of the model are compared with several observations related to polar cap convection.

Structure of the photospheric magnetic field during sector crossings of the heliospheric magnetic field

NASA Astrophysics Data System (ADS)

Getachew, Tibebu; Virtanen, Ilpo; Mursula, Kalevi

2017-04-01

The photospheric magnetic field is the source of the coronal and heliospheric magnetic fields (HMF), but their mutual correspondence is non-trivial and depends on the phase of the solar cycle. The photospheric field during the HMF sector crossings observed at 1 AU has been found to contain enhanced field intensities and definite polarity ordering, forming regions called Hale boundaries. Here we study the structure of the photospheric field during the HMF sector crossings during solar cycles 21-24, separately for the four phases of each solar cycle. We use a refined version of Svalgaard's list of major HMF sector crossings, mapped to the Sun using the solar wind speed observed at the Earth, and the daily level-3 magnetograms of the photospheric field measured at the Wilcox Solar Observatory in 1976-2014. We find that the structure of the photospheric field corresponding to the HMF sector crossings, and the existence and properties of the corresponding Hale bipolar regions varies significantly with solar cycle and with solar cycle phase. We find evidence for Hale boundaries in many, but not all ascending, maximum and declining phases of solar cycles but no minimum phase. The most clear Hale boundaries are found during the (+,-) HMF crossings in the northern hemisphere of odd cycles 21 and 23, but less systematically during the (+,-) crossings in the southern hemisphere of even cycles 22 and 24. We also find that the Hale structure of cycles 23 and 24 is more systematic than during cycles 21 and 22. This may be due to the weakening activity, which reduces the complexity of the photospheric field and clarifies the Hale pattern. The photospheric field distribution also depicts a larger area for the field of the northern hemisphere during the declining and minimum phases, in a good agreement with the bashful ballerina phenomenon. The HMF sector crossings observed at 1AU have only a partial correspondence to Hale boundaries in the photosphere, indicating that the two HMF sectors often originate from the opposite hemispheres across the equator. Our results also give evidence for hemispheric and polarity related differences in the photospheric field between the odd and even solar cycles.

DATA ASSIMILATION APPROACH FOR FORECAST OF SOLAR ACTIVITY CYCLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitiashvili, Irina N., E-mail: irina.n.kitiashvili@nasa.gov

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 relativelymore » 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.« less

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 temperatures, enabling low temperature heat recovery from the receiver and Gas Turbine exhaust gasses.

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.

Capecitabine/cisplatin doublet in anthracycline and taxane pretreated and HER-2 negative metastatic breast carcinoma patients.

PubMed

Ozdemir, N; Aksoy, S; Sendur, M A; Akinci, M B; Yazici, O; Budakoglu, B; Abali, H; Oksuzoglu, B; Zengin, N

2013-01-01

To evaluate the activity and toxicity of the combination of capecitabine and cisplatin (CapCisp) in anthracycline- and taxane-pretreated HER-2 negative metastatic breast carcinoma (MBC) female patients. Patients with HER-2 negative MBC pretreated with anthracycline and taxane and who were then treated with CapCisp combination were retrospectively evaluated. All patients received Cap 1000 mg/m(2) on days 1-14, and Cisp 60 mg/m(2) on day 1, repeated every 3 weeks. In case of disease control without severe toxicity, single agent Cap was continued until progression or unacceptable toxicities after Cisp cessation. Sixty-four MBC patients with median age 43 years (range 20-66) were included the study. Infiltrative ductal carcinoma prevailed (85.9%). Ten percent of the patients had grade I, 42% grade II, and 48.0% grade III tumors. Estrogen receptor (ER) and progesterone receptor (PR) were positive in 48.4 and 51.6% of the patients, respectively. Twenty-eight percent of the patients had triple negative tumors. Almost the entire patient group had this regimen as a third-line treatment. The median combination chemotherapy cycles were 6 (range 2-8). Twenty-seven non-progressive patients continued treatment with single-agent Cap. Median single-agent Cap cycles after the combination chemotherapy were 4 (range 1-38). Disease control rate was 81.3% (complete response 6.3%; partial response 48.4%, stable disease 26.6%, progressive disease 18.8%). Median follow-up time was 10.6 months. Median time to disease progression was 7 months, median overall survival (OS) was 17 months (95% CI, 6.9-16.1) measured from the start of CapCisp chemotherapy. There were no treatment-related deaths. The most frequent grade 3-4 toxicities were neutropenia (8.1%), nausea - vomiting (7.8%) and thrombocytopenia (6.3%). CapCisp doublet has an encouraging antitumor activity with acceptable and manageable toxicity in anthracycline- and taxane-pretreated HER-2 negative metastatic breast carcinoma patients.

Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors

NASA Technical Reports Server (NTRS)

Deland, Matthew T.; Cebula, Richard P.

1994-01-01

Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

Analysis of Solar Spectral Irradiance Measurements from the SBUV/2-Series and the SSBUV Instruments

NASA Technical Reports Server (NTRS)

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

1997-01-01

The NOAA-9 SBEV/2 instrument has made the first regular measurements ot solar UV activity over a complete solar cycle, beginning in March 1985 and continuing as of this writing. The NOAA-9 solar irradiance data set includes the minimum between Cycles 21-22 and the current minimum at the end of Cycle 22. Although overall solar activity is low during these periods, 27-day rotational modulation is frequently present. The episode of 13-day periodicity observed during September 1994 - March 1995 shows that phenomena previously associated with high levels of solar activity can occur at any point in the solar cycle. The 205 nm irradiance and Mg II index measured by NOAA-9 showed very similar behavior during the Cycle 21-22 minimum in 1985-1986, when 27-day periodicity dominated short-term solar variations, but behaved differently in 1994-1995 during the episode of 13-day periodicity. We plan further investigations into the physical causes of this result, since it affects the extent to which the Mg II index is an accurate proxy for 205 nm irradiance variations during such episodes. The NOAA-9 Mg II data are available.

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

Simulated Martian pressure cycle based on the sublimation and deposition of polar CO2

NASA Astrophysics Data System (ADS)

Kemppinen, Osku; Paton, Mark; Savijärvi, Hannu; Harri, Ari-Matti

2014-05-01

The Martian atmospheric pressure cycle is driven by sublimation and deposition of CO2 at polar caps. In the thin atmosphere of Mars the surface energy balance and thus the phase changes of CO2 are dominated by radiation. Additionally, because the atmosphere is so thin, the annual polar cap cycle can have a large relative effect on the pressure. In this work we utilize radiative transfer models to calculate the amount of radiation incoming to Martian polar latitudes over each sol of the year, as well as the amount of energy lost from the surface due to thermal radiation. The energy budget calculated in this way allows us to estimate the amount of CO2 sublimating and depositing at each hour of the Martian year. Since virtually all of the sublimated CO2 is believed to enter and stay in the atmosphere until depositing, this estimate allows us to calculate the annual pressure cycle, assuming that the CO2 is distributed approximately evenly over the planet. The model is running with physically plausible parameters and producing encouragingly good fits to in situ measured data made by e.g. Viking landers. In the next phase we will validate the simulation runs against polar ice cap thickness measurements as well as compare the calculated CO2 source and sink strengths to the sources and sinks of global atmospheric models.

Optoelectronic and Photovoltaic Performances of Pyridine Based Monomer and Polymer Capped ZnO Dye-Sensitized Solar Cells.

PubMed

Singh, Satbir; Raj, Tilak; Singh, Amarpal; Kaur, Navneet

2016-06-01

The present research work describes the comparative analysis and performance characteristics of 4-pyridine based monomer and polymer capped ZnO dye-sensitized solar cells. The N, N-dimethyl-N4-((pyridine-4yl)methylene) propaneamine (4,monomer) and polyamine-4-pyridyl Schiff base (5, polymer) dyes were synthesized through one step condensation reaction between 4-pyridinecarboxaldehyde 1 and N, N-dimethylpropylamine 2/polyamine 3. Products obtained N, N-dimethyl-N4-((pyridine-4yl)methylene)propaneamine (4) and polyamine-4-pyridyl Schiff base (5) were purified and characterized using 1H, 13C NMR, mass, IR and CHN spectroscopy. Both the dyes 4 and 5 were further coated over ZnO nanoparticles and characterized using SEM, DLS and XRD analysis. Absorption profile and emission profile was monitored using fluorescence and UV-Vis absorption spectroscopy. A thick layer of these inbuilt dye linked ZnO nanoparticles of dyes (4) and (5) was pasted on one of the conductive side of ITO glass followed with a liquid electrolyte and counter electrode of the same conductive glass. Polyamine-4-pyridyl Schiff base polymer (5) decorated dye sensitized solar cell has shown better exciting photovoltaic properties in the form of short circuit current density (J(sc) = 6.3 mA/cm2), open circuit photo voltage (V(oc) = 0.7 V), fill factor (FF = 0.736) than monomer decorated dye sensitized solar cell. Polymer dye (5) based ZnO solar cell has shown a maximum solar power to electrical conversion efficiency of 3.25%, which is enhanced by 2.16% in case of monomer dye based ZnO solar cell under AM 1.5 sun illuminations.

SAMPEX Measurements of Geomagnetic-Cutoff Variations During the 4/21/02 Solar Energetic Particle Event

NASA Astrophysics Data System (ADS)

Labrador, A.; Leske, R.; Kanekal, S.; Klecker, B.; Looper, M.; Mazur, J.; Mewaldt, R.

2002-12-01

During large solar energetic particle (SEP) events the entry of solar and interplanetary energetic particles into the upper atmosphere is controlled by the geomagnetic cutoff. We define the cutoff latitude (Λ c) for a given rigidity particle to be effectively the minimum invariant latitude down to which particles can reach the upper atmosphere. The instruments on the polar-orbiting SAMPEX spacecraft have been used to measure geomagnetic cutoffs during a large sample of SEP events from solar cycle 23. During those events in which there is an associated geomagnetic storm, there are often large cutoff variations of as much as 5° to 10° in invariant latitude over the course of the event. This paper will combine measurements from the HILT, MAST, and PET instruments on SAMPEX to provide a comprehensive view of geomagnetic cutoff variations during the large SEP event of 4/21/02. We find that during the first two days of the event the cutoff latitude for ~30 MeV protons was at typical quiet-time levels. On April 23, following the arrival of a strong interplanetary shock, there was a sudden drop in the cutoff that lasted ~12 hours, with sizable local-time differences. During the next two days the cutoff steadily increased, giving a total variation of ~5° over the five days of the event. We combine these measurements of cutoff variations with measurements of the composition and energy spectra in the 4/21/02 event in order to estimate changes in the area of the polar caps over which particles of a given rigidity had access to the upper atmosphere.

The temperature of quiescent streamers during solar cycles 23 and 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

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. Wemore » 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.« less

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.

Effects of the capping ligands, linkers and oxide surface on the electron injection mechanism of copper sulfide quantum dot-sensitized solar cells.

PubMed

Suárez, Javier Amaya; Plata, Jose J; Márquez, Antonio M; Sanz, Javier Fdez

2017-06-07

Quantum dot-sensitized solar cells, QDSCs, are a clean and effective alternative to fossil fuels to reduce CO 2 emissions. However, the different components that constitute the QDSCs and the difficulty of isolating experimentally their effects on the performance of the whole system slow down the development of more efficient devices. In this work, DFT calculations are combined with a bottom-up approach to differentiate the effect of each component on the electronic structure and absorption spectra. First, Cu 2 S QDs were built including a U parameter to effectively describe the localization of electrons. The effect of capping agents is addressed using ligands with different electron-donating/withdrawing groups. The role of linkers and their adsorption on the oxide surface are also examined. Finally, we propose a main indirect electron injection mechanism based on the position of the peaks of the spectra.

A Coupling Function Linking Solar Wind /IMF Variations and Geomagnetic Activity

NASA Astrophysics Data System (ADS)

Lyatsky, W.; Lyatskaya, S.; Tan, A.

2006-12-01

From a theoretical consideration we have obtained expressions for the coupling function linking solar wind and IMF parameters to geomagnetic activity. While deriving these expressions, we took into account (1) a scaling factor due to polar cap expansion while increasing a reconnected magnetic flux in the dayside magnetosphere, and (2) a modified Akasofu function for the reconnected flux for combined IMF Bz and By components. The resulting coupling function may be written as Fa = aVsw B^1/2 sina (q/2), where Vsw is the solar wind speed, B^ is the magnitude of the IMF vector in the Y-Z plane, q is the clock angle between the Z axis and IMF vector in the Y-Z plane, a is a coefficient, and the exponent, a, is derived from the experimental data and equals approximately to 2. The Fa function differs primary by the power of B^ from coupling functions proposed earlier. For testing the obtained coupling function, we used solar wind and interplanetary magnetic field data for four years for maximum and minimum solar activity. We computed 2-D contour plots for correlation coefficients for the dependence of geomagnetic activity indices on solar wind parameters for different coupling functions. The obtained diagrams showed a good correspondence to the theoretic coupling function Fa for a »2. The maximum correlation coefficient for the dependence of the polar cap PC index on the Fa coupling function is significantly higher than that computed for other coupling functions used researchers, for the same time intervals.

Cyclic alternating pattern and interictal epileptiform discharges during morning sleep after sleep deprivation in temporal lobe epilepsy.

PubMed

Giorgi, Filippo Sean; Maestri, Michelangelo; Guida, Melania; Carnicelli, Luca; Caciagli, Lorenzo; Ferri, Raffaele; Bonuccelli, Ubaldo; Bonanni, Enrica

2017-08-01

Sleep deprivation (SD) increases the occurrence of interictal epileptiform discharges (IED) compared to basal EEG in temporal lobe epilepsy (TLE). In adults, EEG after SD is usually performed in the morning after SD. We aimed to evaluate whether morning sleep after SD bears additional IED-inducing effects compared with nocturnal physiological sleep, and whether changes in sleep stability (described by the cyclic alternating pattern-CAP) play a significant role. Adult patients with TLE underwent in-lab night polysomnography (n-PSG) and, within 7days from n-PSG, they underwent also a morning EEG after night SD (SD-EEG). We included only TLE patients in which both recordings showed IED. SD-EEG consisted of waking up patients at 2:00 AM and performing video EEG at 8:00 AM. For both recordings, we obtained the following markers for the first sleep cycle: IED/h (Spike Index, SI), sleep macrostructure, microstructure (NREM CAP rate; A1, A2 and A3 Indices), and SI association with CAP variables. The macrostructure of the first sleep cycle was similar in n-PSG and morning SD-EEG, whereas CAP rate and SI were significantly higher in SD-EEG. SI increase was selectively associated with CAP phases. SD increases the instability of morning recovery sleep compared with n-PSG, and particularly enhances CAP A1 phases, which are associated with the majority of IED. Thus, higher instability of morning recovery sleep may account at least in part for the increased IED yield in SD-EEG in TLE patients. Copyright © 2017 Elsevier Inc. All rights reserved.

The 11 Year Solar Cycle Response of the Equatorial Ionization Anomaly Observed by GPS Radio Occultation

NASA Astrophysics Data System (ADS)

Li, King-Fai; Lin, Li-Ching; Bui, Xuan-Hien; Liang, Mao-Chang

2018-01-01

We have retrieved the latitudinal and vertical structures of the 11 year solar cycle modulation on ionospheric electron density using 14 years of satellite-based radio occultation measurements utilizing the Global Positioning System. The densities at the crests of the equatorial ionization anomaly (EIA) in the subtropics near 300 km in 2003 and 2014 (high solar activity with solar 10.7 cm flux, F10.7 ≈ 140 solar flux unit (sfu)) were 3 times higher than that in 2009 (low solar activity F10.7 ≈ 70 sfu). The higher density is attributed to the elevated solar extreme ultraviolet and geomagnetic activity during high solar activity periods. The location of the EIA crests moved 50 km upward and 10° poleward, because of the enhanced E × B force. The EIA in the northern hemisphere was more pronounced than that in the southern hemisphere. This interhemispheric asymmetry is consistent with the effect of enhanced transequatorial neutral wind. The above observations were reproduced qualitatively by the two benchmark runs of the Thermosphere-Ionosphere-Electrodynamics General Circulation Model. In addition, we have studied the impact of the 11 year solar cycle on the 27 day solar cycle response of the ionospheric electron density. Beside the expected modulation on the amplitude of the 27 day solar variation due to the 11 year solar cycle, we find that the altitude of the maximal 27 day solar response is unexpectedly 50 km higher than that of the 11 year solar response. This is the first time that a vertical dependence of the solar responses on different time scales is reported.

Helioseismic Observations of Two Solar Cycles and Constraints on Dynamo Theory

NASA Astrophysics Data System (ADS)

Kosovichev, Alexander

2018-01-01

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 variations of the differential rotation (“torsional oscillations”) and the 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.

Prediction of the solar modulation of galactic cosmic rays and radiation dose of aircrews up to the solar cycle 26

NASA Astrophysics Data System (ADS)

Miyake, S.; Kataoka, R.; Sato, T.

2016-12-01

The solar modulation of galactic cosmic rays (GCRs), which is the variation of the terrestrial GCR flux caused by the heliospheric environmental change, is basically anti-correlated with the solar activity with so-called 11-year periodicity. In the current weak solar cycle 24, we expect that the flux of GCRs is getting higher than that in the previous solar cycles, leading to the increase in the radiation exposure in the space and atmosphere. In order to quantitatively evaluate the possible solar modulation of GCRs and resultant radiation exposure at flight altitude during the solar cycles 24, 25, and 26, we have developed the time-dependent and three-dimensional model of the solar modulation of GCRs. Our model can give the flux of GCRs anywhere in the heliosphere by assuming the variation of the solar wind velocity, the strength of the interplanetary magnetic field, and its tilt angle. We solve the curvature and gradient drift motion of GCRs in the heliospheric magnetic field, and therefore reproduce the 22-year variation of the solar modulation of GCRs. It is quantitatively confirmed that our model reproduces the energy spectra observed by BESS and PAMELA. We then calculate the variation of the GCR energy spectra during the solar cycles 24, 25, and 26, by extrapolating the solar wind parameters and tilt angle. We also calculate the neutron monitor counting rate and the radiation dose of aircrews at flight altitude, by the air-shower simulation performed by PHITS (Particle and Heavy Ion Transport code System). In this presentation, we report the quantitative forecast values of the solar modulation of GCRs, neutron monitor counting rate, and the radiation dose at flight altitude up to the cycle 26, including the discussion of the charge sign dependence on those results.

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.

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.

Prediction of solar energetic particle event histories using real-time particle and solar wind measurements

NASA Technical Reports Server (NTRS)

Roelof, E. C.; Gold, R. E.

1978-01-01

The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection.

Observations and statistical simulations of a proposed solar cycle/QBO/weather relationship

NASA Technical Reports Server (NTRS)

Baldwin, Mark P.; Dunkerton, Timothy J.

1989-01-01

The 10.7-cm solar flux is observed to be highly correlated with North Pole stratospheric temperatures when partitioned according to the phase of the equatorial stratospheric winds (the quasi-biennial oscillation, or QBO). Calculations show that temperatures over most of the Northern Hemisphere are highly correlated or anticorrelated with North Pole temperatures. The observed spatial pattern of solar-cycle correlations at high latitudes is shown to be not unique to the solar cycle.

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.

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

NASA Astrophysics Data System (ADS)

Meftah, Mustapha

2015-08-01

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

Using a Magnetic Flux Transport Model to Predict the Solar Cycle

NASA Technical Reports Server (NTRS)

Lyatskaya, S.; Hathaway, D.; Winebarger, A.

2007-01-01

We present the results of an investigation into the use of a magnetic flux transport model to predict the amplitude of future solar cycles. Recently Dikpati, de Toma, & Gilman (2006) showed how their dynamo model could be used to accurately predict the amplitudes of the last eight solar cycles and offered a prediction for the next solar cycle - a large amplitude cycle. Cameron & Schussler (2007) found that they could reproduce this predictive skill with a simple 1-dimensional surface flux transport model - provided they used the same parameters and data as Dikpati, de Toma, & Gilman. However, when they tried incorporating the data in what they argued was a more realistic manner, they found that the predictive skill dropped dramatically. We have written our own code for examining this problem and have incorporated updated and corrected data for the source terms - the emergence of magnetic flux in active regions. We present both the model itself and our results from it - in particular our tests of its effectiveness at predicting solar cycles.

A seven-month solar cycle observed with the Langmuir probe on Pioneer Venus Orbiter

NASA Technical Reports Server (NTRS)

Hoegy, W. R.; Wolff, C. L.

1989-01-01

Data collected by the Langmuir probe aboard the Pioneer Venus orbiter (PVO) over the years 1979 though 1987 were normalized to remove the long-period 11-year solar maximum to minimum trend and were analyzed for periodicity. Results yield evidence for the existence of an approximately 7-month solar cycle, which was also observed from SME Lyman alpha and 2800-MHz radio flux measurements carried out from an earth-based platform. This coincidence suggests that the cycle is an intrinsic periodicity in the solar output. The cycle has a frequency independent of the orbital frequency of the PVO and is distinct from a 'rotating beacon' cycle whose period depends on the orbital motion of the PVO about the sun. The second most dominant cycle discovered was a 5-month period. Results of an oscillation model of solar periodicity indicate that the 7-month and 5-month cycles are caused by long-lived flux enhancements from nonlinear interactions of global oscillation modes in the sun's convective envelope (r modes) and radiative interior (g modes).

QBO of temperature in mesopause and lower thermosphere caused by solar activity variations

NASA Astrophysics Data System (ADS)

Shefov, N. N.; Semenov, A. I.

2003-04-01

On the basis of the data of the emission (hydroxyl, sodium and atomic oxygen 557.7 nm) and radiophysical (87-107 km) measurements some regularities of quasi-biennial oscillation (QBO) of the atmospheric temperature at heights of the mesopause and lower thermosphere are investigated. It is shown, that they are closely connected with quasi-biennial variations of solar activity and form within the limits of a cycle of solar activity the fading wave train of oscillations. Such behaviour of the wave train can be adequately described by the Airy function. As a result of the analysis of characteristics of QBO of solar activity during 17-23rd cycles it is shown, that to each 11-years cycle correspond its wave train of QBO. Amplitudes and periods of this wave train decrease during a cycle, i.e. it represents Not harmonious oscillation but it is a cyclic aperiodic oscillation (CAO). Therefore usual methods of Fourier analysis used earlier did not result in the same values of the period. The wave train of the current cycle begins at the end of previous and some time together with the subsequent cycle proceeds. Thus, the time sequence of activity during solar cycle represents superposition of three wave trains. Period of CAO in the beginning of a cycle has ~ 38 months and decreases to the end of a cycle up to ~ 21 months. The first wide negative minimum of Airy function describing of the wave train of CAO corresponds to solar activity minimum in the 11-year cycle. The time scale of the wave train varies from one cycle to another. Full duration of individual wave train is ~ 22 years. Owing to a mutual interference of the consecutive wave trains in the 11-year cycles the observable variations of solar activity are not identical. Structure of CAO obviously displays magnetohydrodynamic processes inside the Sun. This work was supported by the Grant No. 2274 of ISTC.

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.

Field-aligned currents and large scale magnetospheric electric fields

NASA Technical Reports Server (NTRS)

Dangelo, N.

1980-01-01

D'Angelo's model of polar cap electric fields (1977) was used to visualize how high-latitude field-aligned currents are driven by the solar wind generator. The region 1 and region 2 currents of Iijima and Potemra (1976) and the cusp field-aligned currents of Wilhjelm et al. (1978) and McDiarmid et al. (1978) are apparently driven by different generators, although in both cases the solar wind is their ultimate source.

Cyclic Alternating Pattern Is Associated with Cerebral Hemodynamic Variation: A Near-Infrared Spectroscopy Study of Sleep in Healthy Humans

PubMed Central

Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J.

2012-01-01

The cyclic alternating pattern (CAP), that is, cyclic variation of brain activity within non-REM sleep stages, is related to sleep instability and preservation, as well as consolidation of learning. Unlike the well-known electrical activity of CAP, its cerebral hemodynamic counterpart has not been assessed in healthy subjects so far. We recorded scalp and cortical hemodynamics with near-infrared spectroscopy on the forehead and systemic hemodynamics (heart rate and amplitude of the photoplethysmograph) with a finger pulse oximeter during 23 nights in 11 subjects. Electrical CAP activity was recorded with a polysomnogram. CAP was related to changes in scalp, cortical, and systemic hemodynamic signals that resembled the ones seen in arousal. Due to their repetitive nature, CAP sequences manifested as low- and very-low-frequency oscillations in the hemodynamic signals. The subtype A3+B showed the strongest hemodynamic changes. A transient hypoxia occurred during CAP cycles, suggesting that an increased CAP rate, especially with the subtype A3+B, which may result from diseases or fragmented sleep, might have an adverse effect on the cerebral vasculature. PMID:23071658

Cyclic alternating pattern is associated with cerebral hemodynamic variation: a near-infrared spectroscopy study of sleep in healthy humans.

PubMed

Näsi, Tiina; Virtanen, Jaakko; Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J

2012-01-01

The cyclic alternating pattern (CAP), that is, cyclic variation of brain activity within non-REM sleep stages, is related to sleep instability and preservation, as well as consolidation of learning. Unlike the well-known electrical activity of CAP, its cerebral hemodynamic counterpart has not been assessed in healthy subjects so far. We recorded scalp and cortical hemodynamics with near-infrared spectroscopy on the forehead and systemic hemodynamics (heart rate and amplitude of the photoplethysmograph) with a finger pulse oximeter during 23 nights in 11 subjects. Electrical CAP activity was recorded with a polysomnogram. CAP was related to changes in scalp, cortical, and systemic hemodynamic signals that resembled the ones seen in arousal. Due to their repetitive nature, CAP sequences manifested as low- and very-low-frequency oscillations in the hemodynamic signals. The subtype A3+B showed the strongest hemodynamic changes. A transient hypoxia occurred during CAP cycles, suggesting that an increased CAP rate, especially with the subtype A3+B, which may result from diseases or fragmented sleep, might have an adverse effect on the cerebral vasculature.

Comparative study of two precision overdenture attachment designs.

PubMed

Cohen, B I; Pagnillo, M; Condos, S; Deutsch, A S

1996-08-01

In this study two precision overdenture attachment designs were tested for retention--a nylon overdenture cap system and a new cap and keeper system. The new cap and keeper system was designed to reduce the time involved in replacing a cap worn by the conditions of the oral environment. Six groups were tested at two different angles and retentive failure was examined at two different angles (26 and 0 degrees). Failure was measured in pounds with a force gauge over a 2000 pull cycle. The amount of force required to remove caps for two overdenture caps and a replaced cap for the metal keeper system was determined. Two dependent variables were absolute force and relative force. Repeated measures analysis of variance (RMANOVA) was used to compare the between-subjects effects of cap and angle, and the within-subjects effect of pull. The results indicated a significant difference between cap types (p < 0.0001) with respect to the relative force required to remove the cap. There was no effect of angle. For absolute force, RMANOVA revealed a highly significant interaction between pull and cap (p < 0.0001). Thus, the way that force changed over pulls depended on which cap was used (no effect of angle). For relative force, RMANOVA revealed no interaction between pull and cap, but there was a main effect of cap type (p < 0.0001) (no effect of angle). The nylon cap design required less force for removal but showed more consistency in the force required over the course of the 2000 pulls when compared with the keeper with cap insert. The results obtained in this study were consistent with similar studies in literature.

Comprehensive Ionospheric Polar and Auroral Observations for Solar Minimum of Cycle 23/24

NASA Astrophysics Data System (ADS)

Sojka, Jan J.; Nicolls, Michael; van Eyken, Anthony; Heinselman, Craig

Only the incoherent scatter radar (ISR) is able to simultaneously measure full profiles of elec-tron density, ion temperature, and electron temperatures through the E-and F-layers of the terrestrial ionosphere. Historically ISR's have been operated for periods much less than a month. Hence, their measurements do not constitute a continuous sequence from which quiet, disturbed, and storm periods can reliably be discerned. This is particularly true in the auroral and polar regions. During the International Polar Year (IPY) two ISRs achieved close to 24/7 continuous observations. This presentation describes their data sets and specifically how they can provide the IRI with a fiduciary E-and F-region ionosphere descriptions for solar minimum conditions at auroral and polar cap locations. The ionospheric description being electron den-sity, ion temperature, electron temperature, and even molecular ion composition profiles from as low as 90 km extending several scale heights above the F-layer peak. The auroral location is Poker Flat in Alaska at 65.4° N, 147.5° W where the NSF's new Poker Flat Incoherent Scatter Radar (PFISR) is located. During solar minimum conditions this location is in the auroral region for most of the day and is at mid-latitudes, equatorward of the cusp, for about 4 to 8 hours per day dependent upon geomagnetic activity. In contrast the polar location is Svalbard, at 78° N, 16° E where the EISCAT Svalbard Radar (ESR) is located. For most of the day the ESR is in the Northern Polar Cap often with a noon sector passage through the dayside cusp. Of unique relevance to IRI is that these extended observations have enabled the ionospheric morphology to be demarked between quiet and disturbed. During the IPY year, 1 March 2007 to 29 February 2008, a total of 50 solar wind corotating interaction regions (CIRs) impacted geospace. Each CIR has a one-to-three day geomagnetic disturbance that is observed in the ISR auroral and polar observations. Hence, this data set enables the quiet-background ionosphere to be established as a function of season and local time. This quiet-background ionosphere has the unique attribute that it has self-consistent altitude profiles of the density and the temper-ature. This we believe is a true fiduciary reference for the IRI in a high latitude region, that is otherwise particularly difficult to quantify.

A New Polar Magnetic Index of Geomagnetic Activity and its Application to Monitoring Ionospheric Parameters

NASA Technical Reports Server (NTRS)

Lyatsky, Wladislaw; Khazanov, George V.

2008-01-01

For improving the reliability of Space Weather prediction, we developed a new, Polar Magnetic (PM) index of geomagnetic activity, which shows high correlation with both upstream solar wind data and related events in the magnetosphere and ionosphere. Similarly to the existing polar cap PC index, the new, PM index was computed from data from two near-pole geomagnetic observatories; however, the method for computing the PM index is different. The high correlation of the PM index with both solar wind data and events in Geospace environment makes possible to improve significantly forecasting geomagnetic disturbances and such important parameters as the cross-polar-cap voltage and global Joule heating in high latitude ionosphere, which play an important role in the development of geomagnetic, ionospheric and thermospheric disturbances. We tested the PM index for 10-year period (1995-2004). The correlation between PM index and upstream solar wind data for these years is very high (the average correlation coefficient R approximately equal to 0.86). The PM index also shows the high correlation with the cross-polar-cap voltage and hemispheric Joule heating (the correlation coefficient between the actual and predicted values of these parameters is approximately 0.9), which results in significant increasing the prediction reliability of these parameters. Using the PM index of geomagnetic activity provides a significant increase in the forecasting reliability of geomagnetic disturbances and related events in Geospace environment. The PM index may be also used as an important input parameter in modeling ionospheric, magnetospheric, and thermospheric processes.

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.

The effect of the solar field reversal on the modulation of galactic cosmic rays

NASA Technical Reports Server (NTRS)

Thomas, B. T.; Goldstein, B. E.

1983-01-01

There is now a growing awareness that solar cycle related changes in the large-scale structure of the interplanetary magnetic field (IMF) may play an important role in the modulation of galactic cosmic rays. To date, attention focussed on two aspects of the magnetic field structure: large scale compression regions produced by fast solar wind streams and solar flares, both of which are known to vary in intensity and number over the solar cycle, and the variable warp of the heliospheric current sheet. It is suggested that another feature of the solar cycle is worthy of consideration: the field reversal itself. If the Sun reverses its polarity by simply overturning the heliospheric current sheet (northern fields migrating southward and vice-versa) then there may well be an effect on cosmic ray intensity. However, such a simple picture of solar reversal seems improbable. Observations of the solar corona suggest the existence of not one but several current sheets in the heliosphere at solar maximum. The results of a simple calculation to demonstrate that the variation in cosmic ray intensities that will result can be as large as is actually observed over the solar cycle are given.

Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance

NASA Astrophysics Data System (ADS)

Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

2016-09-01

Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

Solar Rotational Modulations of Spectral Irradiance and Correlations with the Variability of Total Solar Irradiance

NASA Technical Reports Server (NTRS)

Lee, Jae N.; Cahalan, Robert F.; Wu, Dong L.

2016-01-01

Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003-2013. Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI. Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.

Changes of Linearity in MF2 Index with R12 and Solar Activity Maximum

NASA Astrophysics Data System (ADS)

Villanueva, L.

2013-05-01

Critical frequency of F2 layer is related to the solar activity, and the sunspot number has been the standard index for ionospheric prediction programs. This layer, being considered the most important in HF radio communications due to its highest electron density, determines the maximum frequency coming back from ground base transmitter signals, and shows irregular variation in time and space. Nowadays the spatial variation, better understood due to the availability of TEC measurements, let Space Weather Centers have observations almost in real time. However, it is still the most difficult layer to predict in time. Short time variations are improved in IRI model, but long term predictions are only related to the well-known CCIR and URSI coefficients and Solar activity R12 predictions, (or ionospheric indexes in regional models). The concept of the "saturation" of the ionosphere is based on data observations around 3 solar cycles before 1970, (NBS, 1968). There is a linear relationship among MUF (0Km) and R12, for smooth Sunspot numbers R12 less than 100, but constant for higher R12, so, no rise of MUF is expected for R12 higher than 100. This recommendation has been used in most of the known Ionospheric prediction programs for HF Radio communication. In this work, observations of smoothed ionospheric index MF2 related to R12 are presented to find common features of the linear relationship, which is found to persist in different ranges of R12 depending on the specific maximum level of each solar cycle. In the analysis of individual solar cycles, the lapse of linearity is less than 100 for a low solar cycle and higher than 100 for a high solar cycle. To improve ionospheric predictions we can establish levels for solar cycle maximum sunspot numbers R12 around low 100, medium 150 and high 200 and specify the ranges of linearity of MUF(0Km) related to R12 which is not only 100 as assumed for all the solar cycles. For lower levels of solar cycle, discussions of present observations are presented.

Experimental study of refrigeration performance based on linear Fresnel solar thermal photovoltaic system

NASA Astrophysics Data System (ADS)

Song, Jinghui; Yuan, Hui; Xia, Yunfeng; Kan, Weimin; Deng, Xiaowen; Liu, Shi; Liang, Wanlong; Deng, Jianhua

2018-03-01

This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy.

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.

Thermodynamic and design considerations of organic Rankine cycles in combined application with a solar thermal gas turbine

NASA Astrophysics Data System (ADS)

Braun, R.; Kusterer, K.; Sugimoto, T.; Tanimura, K.; Bohn, D.

2013-12-01

Concentrated Solar Power (CSP) technologies are considered to provide a significant contribution for the electric power production in the future. Different kinds of technologies are presently in operation or under development, e.g. parabolic troughs, central receivers, solar dish systems and Fresnel reflectors. This paper takes the focus on central receiver technologies, where the solar radiation is concentrated by a field of heliostats in a receiver on the top of a tall tower. To get this CSP technology ready for the future, the system costs have to reduce significantly. The main cost driver in such kind of CSP technologies are the huge amount of heliostats. To reduce the amount of heliostats, and so the investment costs, the efficiency of the energy conversion cycle becomes an important issue. An increase in the cycle efficiency results in a decrease of the solar heliostat field and thus, in a significant cost reduction. The paper presents the results of a thermodynamic model of an Organic Rankine Cycle (ORC) for combined cycle application together with a solar thermal gas turbine. The gas turbine cycle is modeled with an additional intercooler and recuperator and is based on a typical industrial gas turbine in the 2 MW class. The gas turbine has a two stage radial compressor and a three stage axial turbine. The compressed air is preheated within a solar receiver to 950°C before entering the combustor. A hybrid operation of the gas turbine is considered. In order to achieve a further increase of the overall efficiency, the combined operation of the gas turbine and an Organic Rankine Cycle is considered. Therefore an ORC has been set up, which is thermally connected to the gas turbine cycle at two positions. The ORC can be coupled to the solar-thermal gas turbine cycle at the intercooler and after the recuperator. Thus, waste heat from different cycle positions can be transferred to the ORC for additional production of electricity. Within this investigation different working fluids and ORC conditions have been analyzed in order to evaluate the best configuration. The investigations have been performed by application of improved thermodynamic and process analysis tools, which consider the real gas behavior of the analyzed fluids. The results show that by combined operation of the solar thermal gas turbine and the ORC, the combined cycle efficiency is approximately 4%-points higher than in the solar-thermal gas turbine cycle.

Does the Current Minimum Validate (or Invalidate) Cycle Prediction Methods?

NASA Technical Reports Server (NTRS)

Hathaway, David H.

2010-01-01

This deep, extended solar minimum and the slow start to Cycle 24 strongly suggest that Cycle 24 will be a small cycle. A wide array of solar cycle prediction techniques have been applied to predicting the amplitude of Cycle 24 with widely different results. Current conditions and new observations indicate that some highly regarded techniques now appear to have doubtful utility. Geomagnetic precursors have been reliable in the past and can be tested with 12 cycles of data. Of the three primary geomagnetic precursors only one (the minimum level of geomagnetic activity) suggests a small cycle. The Sun's polar field strength has also been used to successfully predict the last three cycles. The current weak polar fields are indicative of a small cycle. For the first time, dynamo models have been used to predict the size of a solar cycle but with opposite predictions depending on the model and the data assimilation. However, new measurements of the surface meridional flow indicate that the flow was substantially faster on the approach to Cycle 24 minimum than at Cycle 23 minimum. In both dynamo predictions a faster meridional flow should have given a shorter cycle 23 with stronger polar fields. This suggests that these dynamo models are not yet ready for solar cycle prediction.

The Effect of "Rogue" Active Regions on the Solar Cycle

NASA Astrophysics Data System (ADS)

Nagy, Melinda; Lemerle, Alexandre; Labonville, François; Petrovay, Kristóf; Charbonneau, Paul

2017-11-01

The origin of cycle-to-cycle variations in solar activity is currently the focus of much interest. It has recently been pointed out that large individual active regions with atypical properties can have a significant impact on the long-term behavior of solar activity. We investigate this possibility in more detail using a recently developed 2×2D dynamo model of the solar magnetic cycle. We find that even a single "rogue" bipolar magnetic region (BMR) in the simulations can have a major effect on the further development of solar activity cycles, boosting or suppressing the amplitude of subsequent cycles. In extreme cases, an individual BMR can completely halt the dynamo, triggering a grand minimum. Rogue BMRs also have the potential to induce significant hemispheric asymmetries in the solar cycle. To study the effect of rogue BMRs in a more systematic manner, a series of dynamo simulations were conducted, in which a large test BMR was manually introduced in the model at various phases of cycles of different amplitudes. BMRs emerging in the rising phase of a cycle can modify the amplitude of the ongoing cycle, while BMRs emerging in later phases will only affect subsequent cycles. In this model, the strongest effect on the subsequent cycle occurs when the rogue BMR emerges around cycle maximum at low latitudes, but the BMR does not need to be strictly cross-equatorial. Active regions emerging as far as 20° from the equator can still have a significant effect. We demonstrate that the combined effect of the magnetic flux, tilt angle, and polarity separation of the BMR on the dynamo is via their contribution to the dipole moment, δ D_{BMR}. Our results indicate that prediction of the amplitude, starting epoch, and duration of a cycle requires an accurate accounting of a broad range of active regions emerging in the previous cycle.

Alternative Ways to Think about Cellular Internal Ribosome Entry*

PubMed Central

Gilbert, Wendy V.

2010-01-01

Internal ribosome entry sites (IRESs) are specialized mRNA elements that allow recruitment of eukaryotic ribosomes to naturally uncapped mRNAs or to capped mRNAs under conditions in which cap-dependent translation is inhibited. Putative cellular IRESs have been proposed to play crucial roles in stress responses, development, apoptosis, cell cycle control, and neuronal function. However, most of the evidence for cellular IRES activity rests on bicistronic reporter assays, the reliability of which has been questioned. Here, the mechanisms underlying cap-independent translation of cellular mRNAs and the contributions of such translation to cellular protein synthesis are discussed. I suggest that the division of cellular mRNAs into mutually exclusive categories of “cap-dependent” and “IRES-dependent” should be reconsidered and that the implications of cellular IRES activity need to be incorporated into our models of cap-dependent initiation. PMID:20576611

Nuclear localization signal regulates porcine circovirus type 2 capsid protein nuclear export through phosphorylation.

PubMed

Hou, Qiang; Hou, Shaohua; Chen, Qing; Jia, Hong; Xin, Ting; Jiang, Yitong; Guo, Xiaoyu; Zhu, Hongfei

2018-02-15

The open reading frame 2 (ORF2) of Porcine circovirus type 2 (PCV2) encodes the major Capsid (Cap) protein, which self-assembles into virus-like particle (VLP) of similar morphology to the PCV2 virion and accumulates in the nucleus through the N-terminal arginine-rich nuclear localization signal (NLS). In this study, PCV2 Cap protein and its derivates were expressed via the baculovirus expression system, and the cellular localization of the recombinant proteins were investigated using anti-Cap mAb by imaging flow cytometry. Analysis of subcellular localization of Cap protein and its variants demonstrated that NLS mediated Cap protein nuclear export as well as nuclear import, and a phosphorylation site (S17) was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the NLS domain to regulate Cap protein nuclear export. Phosphorylation of NLS regulating the PCV2 Cap protein nuclear export was also demonstrated in PK15 cells by fluorescence microscopy. Moreover, the influence of Rep and Rep' protein on Cap protein subcellular localization was investigated in PK15 cells. Phosphorylation of NLS regulating Cap protein nuclear export provides more detailed knowledge of the PCV2 viral life cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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

PubMed

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

2014-12-01

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

A Solar Cycle Prediction Puzzle's PossibleExplanation?

NASA Astrophysics Data System (ADS)

Luhmann, Janet

2007-05-01

A long-standing and intriguing puzzle of the last few decades has been Joan Feynman's (1982) discovery that the solar cycle (sunspot number) maximum trends follow the level of geomagnetic activity during the prior minimum phase. Recently Hathaway (GRL 33, 2006) used this relationship to make a prediction of the size of the next solar maximum. But the physical reason why this should work at all remains a matter of speculation. Although it has been suggested that geomagnetic activity around solar minimum is determined by the terrestrial magnetosphere's response to high speed solar wind streams which seem to often characterize the declining phase of the cycle, why should the occurrence of these streams portend the new solar maximum? Our improving understanding of solar wind sources may hold the key, and also tell us something useful about the solar dynamo.

Latitudinal migration of sunspots based on the ESAI database

NASA Astrophysics Data System (ADS)

Zhang, Juan; Li, Fu-Yu; Feng, Wen

2018-01-01

The latitudinal migration of sunspots toward the equator, which implies there is propagation of the toroidal magnetic flux wave at the base of the solar convection zone, is one of the crucial observational bases for the solar dynamo to generate a magnetic field by shearing of the pre-existing poloidal magnetic field through differential rotation. The Extended time series of Solar Activity Indices (ESAI) elongated the Greenwich observation record of sunspots by several decades in the past. In this study, ESAI’s yearly mean latitude of sunspots in the northern and southern hemispheres during the years 1854 to 1985 is utilized to statistically test whether hemispherical latitudinal migration of sunspots in a solar cycle is linear or nonlinear. It is found that a quadratic function is statistically significantly better at describing hemispherical latitudinal migration of sunspots in a solar cycle than a linear function. In addition, the latitude migration velocity of sunspots in a solar cycle decreases as the cycle progresses, providing a particular constraint for solar dynamo models. Indeed, the butterfly wing pattern with a faster latitudinal migration rate should present stronger solar activity with a shorter cycle period, and it is located at higher latitudinal position, giving evidence to support the Babcock-Leighton dynamo mechanism.

PHOTOMETRIC TRENDS IN THE VISIBLE SOLAR CONTINUUM AND THEIR SENSITIVITY TO THE CENTER-TO-LIMB PROFILE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peck, C. L.; Rast, M. P.

2015-08-01

Solar irradiance variations over solar rotational timescales are largely determined by the passage of magnetic structures across the visible solar disk. Variations on solar cycle timescales are thought to be similarly due to changes in surface magnetism with activity. Understanding the contribution of magnetic structures to total solar irradiance and solar spectral irradiance requires assessing their contributions as a function of disk position. Since only relative photometry is possible from the ground, the contrasts of image pixels are measured with respect to a center-to-limb intensity profile. Using nine years of full-disk red and blue continuum images from the Precision Solarmore » Photometric Telescope at the Mauna Loa Solar Observatory, we examine the sensitivity of continuum contrast measurements to the center-to-limb profile definition. Profiles which differ only by the amount of magnetic activity allowed in the pixels used to determine them yield oppositely signed solar cycle length continuum contrast trends, either agreeing with previous results and showing negative correlation with solar cycle or disagreeing and showing positive correlation with solar cycle. Changes in the center-to-limb profile shape over the solar cycle are responsible for the contradictory contrast results, and we demonstrate that the lowest contrast structures, internetwork and network, are most sensitive to these. Thus the strengths of the full-disk, internetwork, and network photometric trends depend critically on the magnetic flux density used in the quiet-Sun definition. We conclude that the contributions of low contrast magnetic structures to variations in the solar continuum output, particularly to long-term variations, are difficult, if not impossible, to determine without the use of radiometric imaging.« less

Latitude Distribution of Sunspots: Analysis Using Sunspot Data and a Dynamo Model

NASA Astrophysics Data System (ADS)

Mandal, Sudip; Karak, Bidya Binay; Banerjee, Dipankar

2017-12-01

In this paper, we explore the evolution of sunspot latitude distribution and explore its relations with the cycle strength. With the progress of the solar cycle, the distributions in two hemispheres from mid-latitudes propagate toward the equator and then (before the usual solar minimum) these two distributions touch each other. By visualizing the evolution of the distributions in two hemispheres, we separate the solar cycles by excluding this hemispheric overlap. From these isolated solar cycles in two hemispheres, we generate latitude distributions for each cycle, starting from cycle 8 to cycle 23. We find that the parameters of these distributions, namely the central latitude (C), width (δ), and height (H), evolve with the cycle number, and they show some hemispheric asymmetries. Although the asymmetries in these parameters persist for a few successive cycles, they get corrected within a few cycles, and the new asymmetries appear again. In agreement with the previous study, we find that distribution parameters are correlated with the strengths of the cycles, although these correlations are significantly different in two hemispheres. The general trend features, i.e., (i) stronger cycles that begin sunspot eruptions at relatively higher latitudes, and (ii) stronger cycles that have wider bands of sunspot emergence latitudes, are confirmed when combining the data from two hemispheres. We explore these features using a flux transport dynamo model with stochastic fluctuations. We find that these features are correctly reproduced in this model. The solar cycle evolution of the distribution center is also in good agreement with observations. Possible explanations of the observed features based on this dynamo model are presented.

Geoeffectiveness during the early phase of Solar Cycle 24

NASA Astrophysics Data System (ADS)

Pande, Bimal

Geoeffectiveness during the early phase of Solar Cycle 24 \\underline{} Abstract\\underline{} It is very important and interesting to understand the solar eruptions because it produces the geoeffectiveness in our Earth environment. In the rise phase of the solar cycle, geoeffective events are less frequent, thus this provide us better opportunity to study these events including the detection of their source regions. Keeping this in mind, we have analysed the data of rise phase of current solar cycle 24 ( 2009-2012). During above time period, we have selected 59 geoeffective events having Disturbance Storm Time (Dst) index < -50 nT. Based on the Dst index, we divided the events into two categories i.e. moderate (< -50 nT > -100 nT ) and intense ( <-100 nT). To locate the solar source regions of geoeffective and SEPs associated events, we have used available images, movies and Solar Geophysical data (SGD) list: for example movies from SOHO/EIT, images and movies from the Solar Dynamic Observatory (SDO). In this study, we will discuss and compare the different properties of associated CMEs, flares and their relation with geoeffectiveness.

Integration of photovoltaic and concentrated solar thermal technologies for H2 production by the hybrid sulfur cycle

NASA Astrophysics Data System (ADS)

Liberatore, Raffaele; Ferrara, Mariarosaria; Lanchi, Michela; Turchetti, Luca

2017-06-01

It is widely agreed that hydrogen used as energy carrier and/or storage media may significantly contribute in the reduction of emissions, especially if produced by renewable energy sources. The Hybrid Sulfur (HyS) cycle is considered as one of the most promising processes to produce hydrogen through the water-splitting process. The FP7 project SOL2HY2 (Solar to Hydrogen Hybrid Cycles) investigates innovative material and process solutions for the use of solar heat and power in the HyS process. A significant part of the SOL2HY2 project is devoted to the analysis and optimization of the integration of the solar and chemical (hydrogen production) plants. In this context, this work investigates the possibility to integrate different solar technologies, namely photovoltaic, solar central receiver and solar troughs, to optimize their use in the HyS cycle for a green hydrogen production, both in the open and closed process configurations. The analysis carried out accounts for different combinations of geographical location and plant sizing criteria. The use of a sulfur burner, which can serve both as thermal backup and SO2 source for the open cycle, is also considered.

Skylab 2 Solar Physics Experiment

NASA Technical Reports Server (NTRS)

1973-01-01

Skylab 2 Solar Physics Experiment. This black and white view of a solar flare was taken from the skylab remote solar experiment module mounted on top of the vehicle and worked automatically without any interaction from the crew. Solar flares or sunspots are eruptions on the sun's surface and appear to occur in cycles. When these cycles occur, there is worldwide electromagnetic interference affecting radio and television transmission.

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

NASA Astrophysics Data System (ADS)

Scafetta, Nicola

2016-04-01

The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The two side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle can be associated to a quasi-11-year sunspot solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. These frequencies and other oscillations appear once the model is non-linearly processed. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900- 1920 and 1960-1980 and the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature modulation since 1850. The model forecasts a new prolonged solar minimum during 2020-2045, which would be produced mostly by the minima of both the 61 and 115-year reconstructed cycles. Finally, the model predicts that during low solar activity periods, the solar cycle length tends to be longer, as some researchers have claimed. These results clearly indicate that both solar and climate oscillations are linked to planetary motion and, furthermore, their timing can be reasonably hindcast and forecast for decades, centuries and millennia. Scafetta, N.: Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle. J. Atmos. Sol.- Terr. Phys. 80, 296-311 (2012). Scafetta, N.: Does the Sun work as a nuclear fusion amplifier of planetary tidal forcing? A proposal for a physical mechanism based on the mass-luminosity relation. J. Atmos. Sol.-Terr. Phys. 81-82, 27-40 (2012). Scafetta, N.: Discussion on the spectral coherence between planetary, solar and climate oscillations: a reply to some critiques. Astrophys. Space Sci. 354, 275-299 (2014).

A Solar-luminosity Model and Climate

NASA Technical Reports Server (NTRS)

Perry, Charles A.

1990-01-01

Although the mechanisms of climatic change are not completely understood, the potential causes include changes in the Sun's luminosity. Solar activity in the form of sunspots, flares, proton events, and radiation fluctuations has displayed periodic tendencies. Two types of proxy climatic data that can be related to periodic solar activity are varved geologic formations and freshwater diatom deposits. A model for solar luminosity was developed by using the geometric progression of harmonic cycles that is evident in solar and geophysical data. The model assumes that variation in global energy input is a result of many periods of individual solar-luminosity variations. The 0.1-percent variation of the solar constant measured during the last sunspot cycle provided the basis for determining the amplitude of each luminosity cycle. Model output is a summation of the amplitudes of each cycle of a geometric progression of harmonic sine waves that are referenced to the 11-year average solar cycle. When the last eight cycles in Emiliani's oxygen-18 variations from deep-sea cores were standardized to the average length of glaciations during the Pleistocene (88,000 years), correlation coefficients with the model output ranged from 0.48 to 0.76. In order to calibrate the model to real time, model output was graphically compared to indirect records of glacial advances and retreats during the last 24,000 years and with sea-level rises during the Holocene. Carbon-14 production during the last millenium and elevations of the Great Salt Lake for the last 140 years demonstrate significant correlations with modeled luminosity. Major solar flares during the last 90 years match well with the time-calibrated model.

Results of various studies made with the NCAR Thermospheric General Circulation Model (TGCM) (invited review)

NASA Technical Reports Server (NTRS)

Roble, R. G.

1986-01-01

The NCAR thermospheric general circulation model (TGCM) has been used for a variety of thermospheric dynamic studies. It has also been used to compare model predictions with measurements made from various ground-based Fabry-Perot interferometer stations, incoherent scatter radar stations and the Dynamics Explorer satellites. The various input and output features of the model are described. These include the specification of solar EUV fluxes, and descriptions of empirical models to specify auroral particle precipitation, ion drag, and magnetospheric convection. Results are presented for solstice conditions giving the model perturbation temperature and circulation response to solar heating forcing alone and also with the inclusion of magnetospheric convections for two different dawn-dusk potential drops, 20 and 60 kV respectively. Results at two constant pressure levels Z =+1 at 300 km and Z= -4 at 120 km are presented for both the winter and summer polar cap regions. The circulation over the Northern Hemisphere polar cap in both the upper and lower thermosphere are presented along with a figure showing that the circulation is mainly a non-divergent irrotational flow responding to ion drag. The results of a study made on the Southern Hemisphere polar cap during October 1981 where Dynamics Explorer satellite measurements of winds, temperature and composition are compared to TGCM predictions are also presented. A diagnostic package that has been developed to analyze the balance of forces operating in the TGCM is presented next illustrating that in the F-region ion drag and pressure provide the main force balance and in the E-region ion drag, pressure and the coriolis forces provide the main balance. The TGCM prediction for the June 10, 1983 total solar eclipse are next presented showing a thermospheric disturbance following the path of totality. Finally, results are presented giving the global circulation, temperature and composition structure of the thermosphere for solar minimum conditions at equinox with 60 kV magnetospheric convection forcing at high latitudes.

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.

Nonlinear solar cycle forecasting: theory and perspectives

NASA Astrophysics Data System (ADS)

Baranovski, A. L.; Clette, F.; Nollau, V.

2008-02-01

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

The role of in-situ measurements in scintillation modelling

NASA Astrophysics Data System (ADS)

Basu, S.; Basu, S.; Hanson, W. B.

It is shown that the conflicting equatorial scintillation observations obtained from greatly separated ground stations can be organized in the framework of a longitudinal variation of irregularity occurrence, given satellite-borne, in situ measurements of irregularity amplitude of the global F-region irregularity morphology's general features. High-inclination satellite data are used to delineate the morphological features of the polar cap by means of such a method. The lack of diurnal and magnetic control of the irregularity morphology within the low solar flux, northern winter polar cap distinguishes this region from the auroral oval regime. A polar-orbiting communication system sensitive to phase perturbations may observe large differences in the phase-to-amplitude scintillation ratio, as it traverses the auroral oval and proceeds into the polar cap, with its sun-aligned arc system.

Solar Modulation of Inner Trapped Belt Radiation Flux as a Function of Atmospheric Density

NASA Technical Reports Server (NTRS)

Lodhi, M. A. K.

2005-01-01

No simple algorithm seems to exist for calculating proton fluxes and lifetimes in the Earth's inner, trapped radiation belt throughout the solar cycle. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in Cycle 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton fluxes at any time in a given solar cycle, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From flux and its time integral fluence, one can then approximate dose rate and its time integral dose.

Mid-term periodicities and heliospheric modulation of coronal index and solar flare index during solar cycles 22-23

NASA Astrophysics Data System (ADS)

Singh, Prithvi Raj; Saxena, A. K.; Tiwari, C. M.

2018-04-01

We applied fast Fourier transform techniques and Morlet wavelet transform on the time series data of coronal index, solar flare index, and galactic cosmic ray, for the period 1986-2008, in order to investigate the long- and mid-term periodicities including the Rieger ({˜ }130 to {˜ }190 days), quasi-period ({˜ }200 to {˜ }374 days), and quasi-biennial periodicities ({˜ }1.20 to {˜ }3.27 years) during the combined solar cycles 22-23. We emphasize the fact that a lesser number of periodicities are found in the range of low frequencies, while the higher frequencies show a greater number of periodicities. The rotation rates at the base of convection zone have periods for coronal index of {˜ }1.43 years and for solar flare index of {˜ }1.41 year, and galactic cosmic ray, {˜ }1.35 year, during combined solar cycles 22-23. In relation to these two solar parameters (coronal index and solar flare index), for the solar cycles 22-23, we found that galactic cosmic ray modulation at mid cut-off rigidity (Rc = 2.43GV) is anti-correlated with time-lag of few months.

Hybrid nanogenerators for low frequency vibration energy harvesting and self-powered wireless locating

NASA Astrophysics Data System (ADS)

Yuan, Ying; Zhang, Hulin; Wang, Jie; Xie, Yuhang; Khan, Saeed Ahmed; Jin, Long; Yan, Zhuocheng; Huang, Long; Pan, Taisong; Yang, Weiqing; Lin, Yuan

2018-01-01

Hybrid energy harvesters based on different physical effects is fascinating, but a rational design for multiple energy harvesting is challenging. In this work, a spring-magnet oscillator-based triboelectric-electromagnetic generator (EMG) with a solar cell cap is proposed. A power was produced by a triboelectric nanogenerator (TENG) and an EMG independently or simultaneously by using a shared spring-magnet oscillator. The oscillator configuration enables versatile energy harvesting with the excellent size scalability and self-packaged structure which can perform well at low frequency ranging from 3.5 to 5 Hz. The solar cell cap mounted above the oscillator can harvest solar energy. Under vibrations at the frequency of 4 Hz, the TENG and the EMG produced maximum output power of 5.46 nW cm-3 and 378.79 μW cm-3, respectively. The generated electricity by the hybrid nanogenerator can be stored in a capacitor or Li-ion battery, which is capable of powering a wireless locator for real-time locating data reporting to a personal cell phone. The light-weight and handy hybrid nanogenerator can directly light a caution light or play as a portable flashlight by shaking hands at night.

Length of the solar cycle influence on the relationship NAO-Northern Hemisphere Temperature

NASA Astrophysics Data System (ADS)

de La Torre, L.; Gimeno, L.; Tesouro, M.; Añel, J. A.; Nieto, R.; Ribera, P.; García, R.; Hernández, E.

2003-04-01

The influence of the length of the solar cycle on the relationship North Atlantic Oscillation (NAO)-Northern Hemisphere Temperature (NHT) is investigated. The results suggest that this relationship is different according to the length of the solar cycle. When the sunspot cycle is 10 or 11 years long, wintertime NAO and NHT are positively correlated, being the signal more intense during 11 years period, but when the sunspot cycle is longer (12 years) correlations between wintertime NAO and NHT are not significant. In fact there are significant negative correlations between wintertime NAO and spring NHT, with predictive potential.

Solar and Galactic Cosmic Rays Observed by SOHO

NASA Astrophysics Data System (ADS)

Curdt, W.; Fleck, B.

Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to ≈77% of its original level over roughly 1 1/2 solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mechanism. We compare the daily CRF observed by the Oulu station with the daily SOHO SEU rate and with the degradation curve of the solar arrays. The Oulu CRF and the SOHO SSR SEU rate are both modulated by the solar cycle and are highly correlated, except for sharp spikes in the SEU rate, caused by isolated SEP events, which also show up as discontinuities in the otherwise slowly decreasing solar ray efficiency. This allows to discriminate between effects with solar and non-solar origin and to compare the relative strength of both. We find that during solar cycle 23 (1996 Apr 1 -- 2008 Aug 31) only 6% of the total number of SSR SEUs were caused by SEPs; the remaining 94% were due to galactic cosmic rays. During the maximum period of cycle 23 (2000 Jan 1 -- 2003 Dec 31), the SEP contribution increased to 22%, and during 2001, the year with the highest SEP rate, to 30%. About 40% of the total solar array degradation during the 17 years from Jan 1996 through Feb 2013 can be attributed to proton events, i.e. the effect of a series of short-lived, violent SEP events is comparable to the cycle-integrated damage by cosmic rays.

Wind Observations of Anomalous Cosmic Rays from Solar Minimum to Maximum

NASA Technical Reports Server (NTRS)

Reames, D. V.; McDonald, F. B.

2003-01-01

We report the first observation near Earth of the time behavior of anomalous cosmic-ray N, O, and Ne ions through the period surrounding the maximum of the solar cycle. These observations were made by the Wind spacecraft during the 1995-2002 period spanning times from solar minimum through solar maximum. Comparison of anomalous and galactic cosmic rays provides a powerful tool for the study of the physics of solar modulation throughout the solar cycle.

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 on average about twice the length of the spiral magnetic field. The analysis indicates an increase in high-energy SEP events originating from the far-eastern solar hemisphere; for instance, such an event with a well-established associated GOES flare has so far occurred three times during cycle 24 but possibly not at all during cycle 23. The generally lower level of solar activity during cycle 24, as opposed to cycle 23, has probably caused a significant decrease in total ambient pressure in the interplanetary space, leading to a larger proportion of SEP-associated halo-type CMEs. Taken together, these observations point to a qualitative difference between the two solar cycles.

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.

Measurement of the magnetotail reconnection rate

NASA Astrophysics Data System (ADS)

Blanchard, G. T.; Lyons, L. R.; de la Beaujardière, O.; Doe, R. A.; Mendillo, M.

1996-07-01

A technique to measure the magnetotail reconnection rate from the ground is described and applied to 71 hours of measurements from 20 nights. The reconnection rate is obtained from the ionospheric flow across the polar cap boundary in the frame of reference of the boundary, measured by the Sondrestrom incoherent scatter radar. For our measurements, the polar cap boundary is located using 6300 Å auroral emissions and E region electron density. The average experimental uncertainty of the reconnection rate measurement is 11.6 mVm-1 in the ionospheric electric field. By using a large data set, we obtain the dependence of the reconnection rate on magnetic local time, the interplanetary magnetic field, and substorm activity, with much higher accuracy. We find that two thirds of the average polar cap potential drop occurs over the 4-hour segment of the separatrix centered on 2330 MLT, that the linear correlation between the reconnection electric field and the half-wave rectified dawn-dusk solar wind electric field VBs peaks between 1.0 and 1.5 hours, with a maximum linear correlation coefficient of 0.46 at 70 min; and that following substorm expansion phase onset, the reconnection electric field becomes larger than the experimental uncertainty, with an average delay of 23 min. The 70-min delay of the reconnection rate with respect to VBs is a typical convection time for a flux tube across the polar cap. This result indicates that reconnection in the magnetotail is influenced by the solar wind electric field VBs on the field line being reconnected.

Quasi-periodic climatic changes on Mars and earth

NASA Technical Reports Server (NTRS)

Cutts, J. A.; Pollack, J. B.; Toon, O. B.; Howard, A. D.

1981-01-01

Evidence of climatic changes on Mars and the earth due to geologic and astronomical variations is discussed. Finely striped ice-free bands in the Martian polar caps have been taken to indicate that long term variations in the orbit and axial tilt of Mars have precipitated these features at the rate of a mm/yr. Photogrammetric and photometric methods have contributed to measurements of the composition and depth of the Martian caps (14-46 m), and observations of higher solar energy absorption in the northern ice cap implies greater dust deposition in that region than on the south cap; however, the transport mechanisms are not well understood. Comparisons of earth and Martian climatic variations data are made, noting a lack of information on the age intervals of marine and nonmarine sediments on the earth. The possibilities of using quantitative data other than layer thickness to constrain climate models are discussed, and the slope or albedo of layers, or the spacing of polar undulations are suggested.

The Microstructure Evolution and Deformation Behavior of AZ80 During Gradient Increment Cyclic Loading

NASA Astrophysics Data System (ADS)

Ren, Lingbao; Quan, Gaofeng; Boehlert, Carl J.; Zhou, Mingyang; Guo, Yangyang; Fan, Lingling

2018-06-01

Cyclic loading-unloading uniaxial tension experiments were conducted at temperatures ranging between 293 K and 623 K and a strain rate of 10-3 s-1 to study the cyclic accumulated plastic deformation (CAP) behavior of extruded AZ80. The 673 K/4-h heat treatment to the as-extruded AZ80 led to a noticeable decrease in yield strength which was associated with both dissolution of the β-Mg17Al12 phase and growth of the matrix grain size. The critical number of cycles needed to soften the material (N c) decreased from 5 to 4 when the cyclic strain amplitude (ɛ a) increased from 3.3 to 5.0 pct for the as-extruded AZ80. The average cyclic hardening rate (Θ) increased from 11 to 23 MPa/cycle after heat treatment, and this was attributed to the more pronounced twinning process in the coarse-grained microstructure. During the 293 K to 473 K CAP deformation, the increasing accumulated cyclic tension strain may have accelerated the propagation of secondary twinning leading to the Lüders-like post-yield softening. Twinning was prevalent at low temperature (293 K to 473 K) in the ɛ a = 3.0 pct CAP deformation for the heat-treated alloy, and twin-assisted precipitation occurred during the 523 K CAP deformation, which implied that the high diffusivity in the twin boundary accelerated the heterogeneous nucleation of precipitates. The preferred cracking locations changed from twin boundaries to grain boundaries when the CAP deformation temperature increased from 473 K to 523 K. As for the 623 K CAP deformation, cavities initiated at the grain boundaries, and the volume fraction of the cracks/cavities increased from 0.01 to 0.05 with increasing temperature.

ANALYSIS OF SUNSPOT AREA OVER TWO SOLAR CYCLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 betweenmore » 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.« less

Multispacecraft Observations and Modeling of the 22/23 June 2015 Geomagnetic Storm

NASA Technical Reports Server (NTRS)

Reiff, P. H.; Daou, A. G.; Sazykin, S. Y.; Nakamura, R.; Hairston, M. R.; Coffey, V.; Chandler, M. O.; Anderson, B. J.; Russell, C. T.; Welling, D.;

A study of the possible relation of the cardiac arrhythmias occurrence to the polarity reversal of the solar magnetic field

NASA Astrophysics Data System (ADS)

Mavromichalaki, H.; Preka-Papadema, P.; Theodoropoulou, A.; Paouris, E.; Apostolou, Th.

2017-01-01

The biological human system is probably affected by the solar and geomagnetic disturbances as well as the cosmic ray variations. In this work, the relation between the solar activity and cosmic ray variations and the cardiac arrhythmias over the time period 1997-2009 covering the solar cycle 23, is studied. The used medical data set refers to 4741 patients with cardiac arrhythmias and 2548 of whom were diagnosed with atrial fibrillation, obtained from the 2nd Cardiological Clinic of the General Hospital of Nicaea, Piraeus, in Greece. The smoothing method on a 365-day basis and the Pearson r-coefficient were used in order to compare these records with the number of sunspots, flares, solar proton events, coronal mass ejections and cosmic ray intensity. Applying a moving correlation function to ±1500 days, it is suggested that a change of the correlation sign between the medical data and each one of the above parameters occurs during a time interval of about 2-3 years. This interval corresponds to the time span of the polarity reversal of the solar magnetic field of this solar cycle, which always takes place around the solar cycle maximum. After then a correlation analysis was carried out corresponding to the rise (1997-2001) and the decay (2002-2009) phases of the solar cycle 23. It is noticeable that the polarity reversal of the solar magnetic field coincides with the period where the sign of the correlation between the incidence of arrhythmias and the occurrence number of the solar eruptive events and the cosmic ray intensity, changes sign. The results are comparable with those obtained from the previous solar cycle 22 based on medical data from another country.

The Sun's Seismic Radius as Measured from the Fundamental Modes of Oscillations and Its Implications for the TSI Variations

NASA Astrophysics Data System (ADS)

Jain, Kiran; Tripathy, S. C.; Hill, F.

2018-05-01

In this Letter we explore the relationship between the solar seismic radius and total solar irradiance (TSI) during the last two solar cycles using the uninterrupted data from space-borne instruments on board the Solar and Heliospheric Observatory (SoHO) and the Solar Dynamics Observatory (SDO). The seismic radius is calculated from the fundamental (f) modes of solar oscillations utilizing the observations from SoHO/Michelson Doppler Imager (MDI) and SDO/Helioseismic and Magnetic Imager (HMI), and the TSI measurements are obtained from SoHO/VIRGO. Our study suggests that the major contribution to the TSI variation arises from the changes in magnetic field, while the radius variation plays a secondary role. We find that the solar irradiance increases with decreasing seismic radius; however, the anti-correlation between them is moderately weak. The estimated maximum change in seismic radius during a solar cycle is about 5 km, and is consistent in both solar cycles 23 and 24. Previous studies ;suggest a radius change at the surface of the order of 0.06 arcsec to explain the 0.1% variation in the TSI values during the solar cycle; however, our inferred seismic radius change is significantly smaller, hence the TSI variations cannot be fully explained by the temporal changes in seismic radius.

A New Model for the Seasonal Evolution of Triton

NASA Astrophysics Data System (ADS)

Forget, F.; Decamp, N.; Berthier, J.; Le Guyader, C.

2000-10-01

The seasonal evolution of Triton's surface and atmosphere remains poorly understood. No model [1] has been able to fully reproduce the main characterictics of the Voyager 2 observations in 1989 in combination with the "Global warming" recently inferred from stellar occultations [2]. Within this context, we have developped a new thermal model to study the seasonal nitrogen cycle on Triton. The model is the surface part of a Triton atmosphere General circulation model developped at LMD [3]. The nitrogen cycle was found to be very sensitive to Triton complex seasonal variations of the subsolar point latitude, especially during the current decade (south summer solstice). Since only pre-Voyager formulations were available for such a study, this has motivated some new calculations of Triton's motion based on more recent rotationnal elements combined with a relatively complete dynamic solution [4] adapted to Triton. A new analytic formulation suitable for climate modelling has been derived. On this basis, we wish to suggest a new, realistic scenario to explain Triton's apparence and evolution based on solar-induced variation of the frost albedo. Such variations have been observed in Mars CO2 ice seasonal polar caps [5]. Although they seem to result from complex microphysical behavior, they are likely to occur on Triton since both Triton and Mars polar caps are composed of weakly absorbing ice (N2 or CO2) in vapor pressure equilibrium with the main constituant of the atmosphere. [1] e.g. Hansen and Paige, Icarus 99, 273-288 (1992); Brown and Kirk, J. Geophys. Res. 99, 1965-1981 (1994); Spencer and Moore, Icarus 99, 261-272 (1992). [2] Elliot et al., Nature 393, 765-767 (1998). [3] Forget, Descamp and Hourdin, in ``Pluto and Triton, comparisons and evolution over time", Lowell Observatory's fourth annual workshop, Flagstaff, Arizona. (1999) [4] Le Guyader, Astron. Astrophys. 272, 687-694 (1993). [5] Kieffer et al., J. Geophys. Res. 105, 9653-9700 (2000).

Polar low ionospheric responses to the most energetic SPE of the solar cycle#23 based on cosmic noise absorption

NASA Astrophysics Data System (ADS)

Pacini, A. A.; Brum, C. G.

2013-05-01

We present a detailed study of the impact of solar proton event over the polar low ionosphere, occurred in Jan/2005, during the descendent phase of the XXIII solar activity cycle. This event was the hardest SPE of the last solar cycle, and was associated to a solar X-ray flare X.2 and CME halo. For this study, we are using cosmic noise absorption data measured by a riometer located in Oulu, Finland (65oN) along with solar proton data from GOES satellite. Based on computation simulations we intend to explain the 30MHz riometer absorption events based on variations of the flux and spectrum of the energetic particle precipitated.

Polar low ionospheric responses to the most energetic SPE of the solar cycle#23 based on cosmic noise absorption

NASA Astrophysics Data System (ADS)

Pacini, A. A.; Garnett Marques Brum, C.

2013-12-01

We present a detailed study of the impact of solar proton event over the polar low ionosphere, occurred Jan/2005, during the descendent phase of the last solar activity cycle XXIII. This event was the hardest SPE of the last solar cycle, and was associated to a solar X-ray flare X.2 and CME halo. For this study, we are using cosmic noise absorption data measured by a riometer located in Oulu, Finland (65N) along with solar proton data from GOES satellite. Based on computation simulations we intend to explain the 30MHz riometer absorption events based on variations of the flux and spectrum of the energetic particle precipitated.

Quasi-Biennial Oscillation and Solar Cycle Influences over the Winter Arctic Simulated by the WACCM4 Model

NASA Astrophysics Data System (ADS)

Li, K. F.; Limpasuvan, T. L.; Limpasuvan, V.; Tung, K. K.; Yung, Y. L.

2017-12-01

Observations show that the quasi-biennial oscillation (QBO) and the 11-year solar cycle perturb the polar vortex via planetary wave convergence at high latitudes, a mechanism first proposed by Holton and Tan in 1980. Their perturbations lead to increases of stratospheric sudden warming events, and hence observable increases in temperature and ozone abundance in the polar vortex, during the easterly phase of QBO and the solar maximum. Here we simulate the changes in the polar atmosphere using the Whole Atmosphere Community Climate Model 4 (WACCM4) with the prescribed QBO and 11-year solar cycle forcing. The simulation is diagnosed in four groups: westerly QBO phase and solar minimum, westerly QBO phase and solar maximum, easterly QBO phase and solar minimum, and easterly QBO phase and solar maximum. The simulated changes in temperature and ozone are compared with satellite observations.

Multi-objective thermodynamic optimisation of supercritical CO2 Brayton cycles integrated with solar central receivers

NASA Astrophysics Data System (ADS)

Vasquez Padilla, Ricardo; Soo Too, Yen Chean; Benito, Regano; McNaughton, Robbie; Stein, Wes

2018-01-01

In this paper, optimisation of the supercritical CO? Brayton cycles integrated with a solar receiver, which provides heat input to the cycle, was performed. Four S-CO? Brayton cycle configurations were analysed and optimum operating conditions were obtained by using a multi-objective thermodynamic optimisation. Four different sets, each including two objective parameters, were considered individually. The individual multi-objective optimisation was performed by using Non-dominated Sorting Genetic Algorithm. The effect of reheating, solar receiver pressure drop and cycle parameters on the overall exergy and cycle thermal efficiency was analysed. The results showed that, for all configurations, the overall exergy efficiency of the solarised systems achieved at maximum value between 700°C and 750°C and the optimum value is adversely affected by the solar receiver pressure drop. In addition, the optimum cycle high pressure was in the range of 24.2-25.9 MPa, depending on the configurations and reheat condition.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egeland, Ricky; Metcalfe, Travis S.; Hall, Jeffrey C.

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

Anomalous and Galactic Cosmic Ray Intensities at 1 AU During the Approach to the Cycle 24/25 Solar Minimum and Throughout the Last 20 Years

NASA Astrophysics Data System (ADS)

Leske, R. A.; Cummings, A. C.; Mewaldt, R. A.; Cohen, C.; Stone, E. C.; Wiedenbeck, M. E.

2017-12-01

Anomalous cosmic ray (ACR) intensities at 1 AU generally track galactic cosmic ray (GCR) intensities, but with differences between solar polarity cycles: at high rigidities, GCRs reach higher peak intensities during A<0 cycles, while ACRs have been higher at A>0 solar minima. At present, during the approach to an A>0 solar minimum, ACR oxygen above 8 MeV/nucleon as measured by the Advanced Composition Explorer (ACE) has already reached the peak intensities seen during the 2009 A<0 solar minimum, but is still 40% below the levels seen in 1997 during the last A>0 minimum. The GCR iron intensity at 300 MeV/nucleon, on the other hand, is presently comparable to that in 1997 but remains 10% below its record-setting 2009 value. Drift effects play an important role in the modulation of both ACRs and GCRs. Positively charged ions drift inward along the heliospheric current sheet (HCS) during A<0 cycles and their intensities are thus sensitive to the HCS tilt angle, which remained high for much of the last solar cycle. We have previously shown that both ACR and GCR intensities were significantly higher for a given HCS tilt angle during the 2000-2012 A<0 cycle than they were during the prior (1980-1990) A<0 cycle, and this trend appears to be continuing into the new A>0 cycle. But while GCR intensities in 2009 reached the highest levels recorded during the last 50 years, ACR intensities were only similar to those in the 1980s A<0 minimum. Factors such as a weaker interplanetary magnetic field, perhaps with a reduction in the ACR source strength or greater sensitivity of ACRs than GCRs to the HCS tilt angle, may account for the difference in their modulation behavior.We present 20 years of ACR and GCR intensity data acquired by ACE throughout two solar cycles, with emphasis on recent observations, and discuss possible reasons for the differences in the relative behavior of ACRs and GCRs in the different solar cycles.

Antifungal activity of fused Mannich ketones triggers an oxidative stress response and is Cap1-dependent in Candida albicans.

PubMed

Rossignol, Tristan; Kocsis, Béla; Bouquet, Orsolya; Kustos, Ildikó; Kilár, Ferenc; Nyul, Adrien; Jakus, Péter B; Rajbhandari, Kshitij; Prókai, László; d'Enfert, Christophe; Lóránd, Tamás

2013-01-01

We investigated the antifungal activity of fused Mannich ketone (FMK) congeners and two of their aminoalcohol derivatives. In particular, FMKs with five-membered saturated rings were shown to have minimum inhibitory concentration (MIC90s) ranging from 0.8 to 6 µg/mL toward C. albicans and the closely related C. parapsilosis and C. krusei while having reduced efficacy toward C. glabrata and almost no efficacy against Aspergillus sp. Transcript profiling of C. albicans cells exposed for 30 or 60 min to 2-(morpholinomethyl)-1-indanone, a representative FMK with a five-membered saturated ring, revealed a transcriptional response typical of oxidative stress and similar to that of a C. albicans Cap1 transcriptional activator. Consistently, C. albicans lacking the CAP1 gene was hypersensitive to this FMK, while C. albicans strains overexpressing CAP1 had decreased sensitivity to 2-(morpholinomethyl)-1-indanone. Quantitative structure-activity relationship studies revealed a correlation of antifungal potency and the energy of the lowest unoccupied molecular orbital of FMKs and unsaturated Mannich ketones thereby implicating redox cycling-mediated oxidative stress as a mechanism of action. This conclusion was further supported by the loss of antifungal activity upon conversion of representative FMKs to aminoalcohols that were unable to participate in redox cycles.

11- and 22-year variations of the cosmic ray density and of the solar wind speed

NASA Technical Reports Server (NTRS)

Chirkov, N. P.

1985-01-01

Cosmic ray density variations for 17-21 solar activity cycles and the solar wind speed for 20-21 events are investigated. The 22-year solar wind speed recurrence was found in even and odd cycles. The 22-year variations of cosmic ray density were found to be opposite that of solar wind speed and solar activity. The account of solar wind speed in 11-year variations significantly decreases the modulation region of cosmic rays when E = 10-20 GeV.

Structure of the Photospheric Magnetic Field During Sector Crossings of the Heliospheric Magnetic Field

NASA Astrophysics Data System (ADS)

Getachew, Tibebu; Virtanen, Ilpo; Mursula, Kalevi

2017-11-01

The photospheric magnetic field is the source of the coronal and heliospheric magnetic fields (HMF), but their mutual correspondence is non-trivial and depends on the phase of the solar cycle. The photospheric field during the HMF sector crossings observed at 1 AU has been found to contain enhanced field intensities and definite polarity ordering, forming regions called Hale boundaries. Here we separately study the structure of the photospheric field during the HMF sector crossings during Solar Cycles 21 - 24 for the four phases of each solar cycle. We use a refined version of Svalgaard's list of major HMF sector crossings, mapped to the Sun using the solar wind speed observed at Earth, and the daily level-3 magnetograms of the photospheric field measured at the Wilcox Solar Observatory in 1976 - 2016. We find that the structure of the photospheric field corresponding to the HMF sector crossings and the existence and properties of the corresponding Hale bipolar regions varies significantly with solar cycle, solar cycle phase, and hemisphere. The Hale boundaries in more than half of the ascending, maximum, and declining phases are clear and statistically significant. The clearest Hale boundaries are found during the (+,-) HMF crossings in the northern hemisphere of odd Cycles 21 and 23, but less systematical during the (+,-) crossings in the southern hemisphere of even Cycles 22 and 24. No similar difference between odd and even cycles is found for the (-,+) crossings. This shows that the northern hemisphere has a more organized Hale pattern overall. The photospheric field distribution also depicts a larger area for the field of the northern hemisphere during the declining and minimum phases, in a good agreement with the bashful ballerina phenomenon.

Study of radiatively sustained cesium plasmas for solar energy conversion

NASA Technical Reports Server (NTRS)

Palmer, A. J.; Dunning, G. J.

1980-01-01

The results of a study aimed at developing a high temperature solar electric converter are reported. The converter concept is based on the use of an alkali plasma to serve as both an efficient high temperature collector of solar radiation as well as the working fluid for a high temperature working cycle. The working cycle is a simple magnetohydrodynamic (MHD) Rankine cycle employing a solid electrode Faraday MHD channel. Research milestones include the construction of a theoretical model for coupling sunlight in a cesium plasma and the experimental demonstration of cesium plasma heating with a solar simulator in excellent agreement with the theory. Analysis of a solar MHD working cycle in which excimer laser power rather than electric power is extracted is also presented. The analysis predicts a positive gain coefficient on the cesium-xenon excimer laser transition.

Methods for Cloud Cover Estimation

NASA Technical Reports Server (NTRS)

Glackin, D. L.; Huning, J. R.; Smith, J. H.; Logan, T. L.

1984-01-01

Several methods for cloud cover estimation are described relevant to assessing the performance of a ground-based network of solar observatories. The methods rely on ground and satellite data sources and provide meteorological or climatological information. One means of acquiring long-term observations of solar oscillations is the establishment of a ground-based network of solar observatories. Criteria for station site selection are: gross cloudiness, accurate transparency information, and seeing. Alternative methods for computing this duty cycle are discussed. The cycle, or alternatively a time history of solar visibility from the network, can then be input to a model to determine the effect of duty cycle on derived solar seismology parameters. Cloudiness from space is studied to examine various means by which the duty cycle might be computed. Cloudiness, and to some extent transparency, can potentially be estimated from satellite data.

Predicting the La Niña of 2020-21: Termination of Solar Cycles and Correlated Variance in Solar and Atmospheric Variability

NASA Astrophysics Data System (ADS)

Leamon, R. J.; McIntosh, S. W.

2017-12-01

Establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge across the spectrum of Earth-system science. Over the past few years a new picture to describe solar variability has developed, based on observing, understanding and tracing the progression, interaction and intrinsic variability of the magnetized activity bands that belong to the Sun's 22-year magnetic activity cycle. The intra- and extra-hemispheric interaction of these magnetic bands appear to explain the occurrence of decadal scale variability that primarily manifests itself in the sunspot cycle. However, on timescales of ten months or so, those bands posses their own internal variability with an amplitude of the same order of magnitude as the decadal scale. The latter have been tied to the existence of magnetized Rossby waves in the solar convection zone that result in surges of magnetic flux emergence that correspondingly modulate our star's radiative and particulate output. One of the most important events in the progression of these bands is their (apparent) termination at the solar equator that signals a global increase in magnetic flux emergence that becomes the new solar cycle. We look at the particulate and radiative implications of these termination points, their temporal recurrence and signature, from the Sun to the Earth, and show the correlated signature of solar cycle termination events and major oceanic oscillations that extend back many decades. A combined one-two punch of reduced particulate forcing and increased radiative forcing that result from the termination of one solar cycle and rapid blossoming of another correlates strongly with a shift from El Niño to La Niña conditions in the Pacific Ocean. This shift does not occur at solar minima, nor solar maxima, but at a particular, non-periodic, time in between. The failure to identify these termination points, and their relative irregularity, have inhibited a correlation to be observed and physical processes to be studied. This result potentially opens the door to a broader understanding of solar variability on our planet and its weather. Ongoing tracking of solar magnetic band migration indicates that Cycle 24 will terminate in the 2020 timeframe and thus we may expect to see an attendant shift to La Niña conditions at that time.

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.;

Study the gradient characteristics of the ionosphere at equatorial latitude during the latest cycle of solar activity

NASA Astrophysics Data System (ADS)

Nguyen Thai, Chinh; Temitope Seun, Oluwadare; Le Thi, Nhung; Schuh, Harald

2017-04-01

The sun has its own seasons with an average duration of about 11 years. In this time, the sun enters a period of increased activity called the solar maximum and a period of decreased activity called the solar minimum. Cycles span from one minimum to the next. The current solar cycle is 24, which began on January 4, 2008 and is expected to be ended in 2019. During this period, the ionosphere changes its thickness and its characteristics as well. The change is most complicated and unpredictable at the equatorial latitudes in a band around 150 northward and 150 southward from the equator. Thailand is located in these regions is known as one of the countries most affected by the ionosphere change. Ionospheric information such as the vertical total electron content (VTEC) and scintillation indices can be extracted from the measurements of GNSS dual-frequency receivers. In this study, a Matlab tool is programmed to calculate some ionosphere parameters from the normal RINEX observation file including VTEC value, amplitude scintillation S4 index and others. The value of VTEC at one IGS station in Thailand (13.740N, 100.530E) is computed for almost one full solar cycle, that is 8 years, from 2009 to 2016. From these results, we are able to derive the rules of TEC variation over time and its dependence on solar activity in the equatorial regions. The change of VTEC is estimated in diurnal, seasonal and annual variation for the latest solar cycle. The solar cycle can be represented in several ways, in this paper we use the sunspot number and the F10.7 cm radio flux to describe the solar activity. The correlation coefficients between these solar indices and the monthly maximum of VTEC value are around 0.87, this indicates a high dependence of the ionosphere on solar activity. Besides, a scintillation map derived from GNSS data is displayed to indicate the intensity of scintillation activity.

Solar Activity Forecasting for use in Orbit Prediction

NASA Technical Reports Server (NTRS)

Schatten, Kenneth

2001-01-01

Orbital prediction for satellites in low Earth orbit (LEO) or low planetary orbit depends strongly on exospheric densities. Solar activity forecasting is important in orbital prediction, as the solar UV and EUV inflate the upper atmospheric layers of the Earth and planets, forming the exosphere in which satellites orbit. Geomagnetic effects also relate to solar activity. Because of the complex and ephemeral nature of solar activity, with different cycles varying in strength by more than 100%, many different forecasting techniques have been utilized. The methods range from purely numerical techniques (essentially curve fitting) to numerous oddball schemes, as well as a small subset, called 'Precursor techniques.' The situation can be puzzling, owing to the numerous methodologies involved, somewhat akin to the numerous ether theories near the turn of the last century. Nevertheless, the Precursor techniques alone have a physical basis, namely dynamo theory, which provides a physical explanation for why this subset seems to work. I discuss this solar cycle's predictions, as well as the Sun's observed activity. I also discuss the SODA (Solar Dynamo Amplitude) index, which provides the user with the ability to track the Sun's hidden, interior dynamo magnetic fields. As a result, one may then update solar activity predictions continuously, by monitoring the solar magnetic fields as they change throughout the solar cycle. This paper ends by providing a glimpse into what the next solar cycle (#24) portends.

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.

Closed Cycle Engine Program Used in Solar Dynamic Power Testing Effort

NASA Technical Reports Server (NTRS)

Ensworth, Clint B., III; McKissock, David B.

1998-01-01

NASA Lewis Research Center is testing the world's first integrated solar dynamic power system in a simulated space environment. This system converts solar thermal energy into electrical energy by using a closed-cycle gas turbine and alternator. A NASA-developed analysis code called the Closed Cycle Engine Program (CCEP) has been used for both pretest predictions and post-test analysis of system performance. The solar dynamic power system has a reflective concentrator that focuses solar thermal energy into a cavity receiver. The receiver is a heat exchanger that transfers the thermal power to a working fluid, an inert gas mixture of helium and xenon. The receiver also uses a phase-change material to store the thermal energy so that the system can continue producing power when there is no solar input power, such as when an Earth-orbiting satellite is in eclipse. The system uses a recuperated closed Brayton cycle to convert thermal power to mechanical power. Heated gas from the receiver expands through a turbine that turns an alternator and a compressor. The system also includes a gas cooler and a radiator, which reject waste cycle heat, and a recuperator, a gas-to-gas heat exchanger that improves cycle efficiency by recovering thermal energy.

In Search of Sun-Climate Connection Using Solar Irradiance Measurements and Climate Records

NASA Technical Reports Server (NTRS)

Kiang, Richard K.; Kyle, H. Lee

2000-01-01

The Earth's temperature has risen approximately 0.5 degree-C in the last 150 years. Because the atmospheric concentration of carbon dioxide has increased nearly 30% since the industrial revolution, a common conjecture, supported by various climate models, is that anthropogenic greenhouse gases have contributed to global warming. Another probable factor for the warming is the natural variation of solar irradiance. Although the variation is as small as 0.1 % it is hypothesized that it contributes to part of the temperature rise. Warmer or cooler ocean temperature at one part of the Globe may manifest as abnormally wet or dry weather patterns some months or years later at another part of the globe. Furthermore, the lower atmosphere can be affected through its coupling with the stratosphere, after the stratospheric ozone absorbs the ultraviolet portion of the solar irradiance. In this paper, we use wavelet transforms based on Morlet wavelet to analyze the time-frequency properties in several datasets, including the Radiation Budget measurements, the long-term total solar irradiance time series, the long-term temperature at two locations for the North and the South Hemisphere. The main solar cycle, approximately 11 years, are identified in the long-term total solar irradiance time series. The wavelet transform of the temperature datasets show annual cycle but not the solar cycle. Some correlation is seen between the length of the solar cycle extracted from the wavelet transform and the North Hemisphere temperature time series. The absence of the 11-year cycle in a time series does not necessarily imply that the geophysical parameter is not affected by the solar cycle; rather it simply reflects the complex nature of the Earth's response to climate forcings.

Periodic analysis of solar activity and its link with the Arctic oscillation phenomenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Weizheng; Li, Chun; Du, Ling

2014-12-01

Based on spectrum analysis, we provide the arithmetic expressions of the quasi 11 yr cycle, 110 yr century cycle of relative sunspot numbers, and quasi 22 yr cycle of solar magnetic field polarity. Based on a comparative analysis of the monthly average geopotential height, geopotential height anomaly, and temperature anomaly of the northern hemisphere at locations with an air pressure of 500 HPa during the positive and negative phases of AO (Arctic Oscillation), one can see that the abnormal warming period in the Arctic region corresponds to the negative phase of AO, while the anomalous cold period corresponds to itsmore » positive phase. This shows that the abnormal change in the Arctic region is an important factor in determining the anomalies of AO. In accordance with the analysis performed using the successive filtering method, one can see that the AO phenomenon occurring in January shows a clear quasi 88 yr century cycle and quasi 22 yr decadal cycle, which are closely related to solar activities. The results of our comparative analysis show that there is a close inverse relationship between the solar activities (especially the solar magnetic field index changes) and the changes in the 22 yr cycle of the AO occurring in January, and that the two trends are basically opposite of each other. That is to say, in most cases after the solar magnetic index MI rises from the lowest value, the solar magnetic field turns from north to south, and the high-energy particle flow entering the Earth's magnetosphere increases to heat the polar atmosphere, thus causing the AO to drop from the highest value; after the solar magnetic index MI drops from the highest value, the solar magnetic field turns from south to north, and the solar high-energy particle flow passes through the top of the Earth's magnetosphere rather than entering it to heat the polar atmosphere. Thus the polar temperature drops, causing the AO to rise from the lowest value. In summary, the variance contribution rate of the changes in the quasi 110 yr century cycle and quasi 22 yr decadal cycle for the AO reaches 62.9%, indicating that solar activity is an important driving factor of the AO.« less

Observations of Space Weather and Space Climate Over the Past 15 Years From SABER (And Longer!)

NASA Technical Reports Server (NTRS)

Mlynczak, Marty; Hunt, Linda; Russell, James M., III

2016-01-01

The global infrared (IR) energy budget of the thermosphere has been reconstructed back 70 years (to 1947). IR cooling, integrated over a solar cycle, is relatively constant over the 5 complete cycles (19 -23) studied. Result implies that solar energy (particles and photons) has similar, small (< 7%) variation from one cycle to next. From Earth's upper atmosphere perspective, solar cycles are really more similar than different, over their length. No consistent relationship between peak of IR cooling and sunspot number peak. Results submitted to GRL 8/2016.

Intensity Variations of Narrow Bands of Solar UV Radiation during Descending Phases of SACs 21-23

NASA Astrophysics Data System (ADS)

Gigolashvili, M.; Kapanadze, N.

2014-12-01

The study of variations of four narrow bands of solar spectral irradiance (SSI) in the ultraviolet (UV) range for period 1981-2008 is presented. Observational data obtained by space-flight missions SORCE, UARS, SME and daily meanings of international sunspot number (ISN) have been used. The investigated data cover the decreasing phases of the solar activity cycles (SACs) 21, 22 and 23. We have revealed a peculiar behavior of intensity variability of some solar ultraviolet spectral lines originated in the solar chromospheres for period corresponding to the declining phase of the solar cycle 23. It is found that variability of emission of different solar spectral narrow bands (289.5 nm, 300.5 nm) does not agree equally well with ISN variability during decreasing phase of the solar activity cycle 23. The negative correlations between total solar irradiance and the solar spectral narrow bands of UV emission (298.5 nm, 300.5 nm) had been revealed. The existence of the negative correlation can be explained by the sensitivity of SSI of some emission lines to the solar global magnetic field.

A transient plasticity study and low cycle fatigue analysis of the Space Station Freedom photovoltaic solar array blanket

NASA Technical Reports Server (NTRS)

Armand, Sasan C.; Liao, Mei-Hwa; Morris, Ronald W.

1990-01-01

The Space Station Freedom photovoltaic solar array blanket assembly is comprised of several layers of materials having dissimilar elastic, thermal, and mechanical properties. The operating temperature of the solar array, which ranges from -75 to +60 C, along with the material incompatibility of the blanket assembly components combine to cause an elastic-plastic stress in the weld points of the assembly. The weld points are secondary structures in nature, merely serving as electrical junctions for gathering the current. The thermal mechanical loading of the blanket assembly operating in low earth orbit continually changes throughout each 90 min orbit, which raises the possibility of fatigue induced failure. A series of structural analyses were performed in an attempt to predict the fatigue life of the solar cell in the Space Station Freedom photovoltaic array blanket. A nonlinear elastic-plastic MSC/NASTRAN analysis followed by a fatigue calculation indicated a fatigue life of 92,000 to 160,000 cycles for the solar cell weld tabs. Additional analyses predict a permanent buckling phenomenon in the copper interconnect after the first loading cycle. This should reduce or eliminate the pulling of the copper interconnect on the joint where it is welded to the silicon solar cell. It is concluded that the actual fatigue life of the solar array blanket assembly should be significantly higher than the calculated 92,000 cycles, and thus the program requirement of 87,500 cycles (orbits) will be met. Another important conclusion that can be drawn from the overall analysis is that, the strain results obtained from the MSC/NASTRAN nonlinear module are accurate to use for low-cycle fatigue analysis, since both thermal cycle testing of solar cells and analysis have shown higher fatigue life than the minimum program requirement of 87,500 cycles.

High LMD GCM Resolution Modeling of the Seasonal Evolution of the Martian Northern Permanent Cap: Comparison with Mars Express OMEGA Observations

NASA Technical Reports Server (NTRS)

Levrard, B.; Forget, F.; Montmessin, F.; Schmitt, B.; Doute, S.; Langevin, Y.; Poulet, F.; Bibring, J. P.; Gondet, B.

2005-01-01

Analyses of imaging data from Mariner, Viking and MGS have shown that surface properties (albedo, temperature) of the northern cap present significant differences within the summer season and between Mars years. These observations include differential brightening and/or darkening between polar areas from the end of the spring to midsummer. These differences are attributed to changes in grain size or dust content of surface ice. To better understand the summer behavior of the permanent northern polar cap, we perfomed a high resolution modeling (approximately 1 deg x 1 deg.) of northern cap in the Martian Climate/water cycle as simulated by the Laboratoire de Meteorologie Dynamique (LMD) global climate model. We compare the predicted properties of the surface ice (ice thickness, temperature) with the Mars Express Omega summer observations of the northern cap. albedo and thermal inertia svariations model. In particular, albedo variations could be constrained by OMEGA data. Meteorological predictions of the LMD GCM wil be presented at the conference to interpret the unprecedently resolved OMEGA observations. The specific evolution of regions of interest (cap center, Chasma Boreal...) and the possibility of late summer global cap brightening will be discussed.

Radio Imaging Observations of Solar Activity Cycle and Its Anomaly

NASA Astrophysics Data System (ADS)

Shibasaki, K.

2011-12-01

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

The economics of solar powered absorption cooling

NASA Technical Reports Server (NTRS)

Bartlett, J. C.

1978-01-01

Analytic procedure evaluates cost of combining absorption-cycle chiller with solar-energy system in residential or commercial application. Procedure assumes that solar-energy system already exists to heat building and that cooling system must be added. Decision is whether to cool building with conventional vapor-compression-cycle chiller or to use solar-energy system to provide heat input to absorption chiller.

Recent Glaciers on Mars: Description and Solar System Perspective

NASA Astrophysics Data System (ADS)

Kargel, J. S.

2001-11-01

Active or recently active ice deposits occur on Mars at middle and high latitudes in fretted terrain, around massifs in highlands east of Hellas and in southern Argyre, on crater walls in the highlands, and in the south polar cap. Most mid-latitude icy flows are debris covered, apparently stagnant, and eroded by partial sublimation. Others are scarred by fresh crevasses and gullies, thus suggesting recent deformation and surface melting. Erosional features include a variety of small-scale relief elements due mainly to sublimation, but sublimation has not obliterated evidence of flow. Similar to terrestrial glaciers in many respects, there are also notable differences, especially in the nature of accumulation. Deformation of the south polar cap is indicated by folding, boudinage, strike-slip or normal faulting, forebulge tectonics near scarps, and thrust faulting. The north polar cap locally also exhibits flow indicators. The south cap's glacial features suggest interbedding of two or more types of ice of differing volatility and rheology, plus a locally deforming surficial dry-ice cap overlying the other materials. Major ice types may include two (or more) of the following, in order of highest to lowest mechanical strength: CO2 clathrate hydrate, water ice, water ice containing traces of liquid-soluble salts, water ice containing traces of solid-soluble acids, and CO2 ice; dust is another variable. Within our Solar System, the closest geomorphic analog to icy Martian flows are Earth's alpine glaciers, rock glaciers, and continental ice sheets, though key differences are apparent. If made dominantly of water ice, important and recent climatic shifts seem to be implicated. Ice-flow landforms also occur on some outer planet satellites; among them are Io, Europa, Enceladus, Ariel, and Triton. Volatile flows on these bodies may involve diverse materials, such as sulfur, water ice, hydrated salts, ammonia-water ices, and nitrogen ice. Most of these would not be suitable materials on Mars. This work was funded by grants from the NASA Mars Data Analysis Program.

A reexamination of the QBO period modulation by the solar cycle

NASA Astrophysics Data System (ADS)

Fischer, P.; Tung, K. K.

2008-04-01

Using the updated Singapore wind from 1953 to 2007 for the lower stratosphere 70-10 hPa, courtesy of Barbara Naujokat of Free University of Berlin, we examine the variation of the period of the Quasi-Biennial Oscillation (QBO) as a function of height and its modulation in time by the 11-year solar cycle. The analysis is supplemented by the ERA-40 reanalysis up to 1 hPa. Previously, it was reported that the descent of the easterly shear zone tends to stall near 30 hPa during solar minimum, leading to a lengthened QBO westerly duration near 44-50 hPa and the reported anticorrelation of the westerly duration and the solar cycle. Using an objective method, continuous wavelet transform (CWT), for the determination of local QBO period, we find that the whole QBO period is almost invariant with respect to height, so that the stalling mechanism affects only the partition of the whole period between easterly and westerly durations. Using this longest data set available for equatorial stratospheric wind, which spans five and half solar cycles (six solar minima), we find that in three solar minima, the QBO period is lengthened, while in the remaining almost three solar cycles, the QBO period is lengthened instead at solar maxima. We suggest that the decadal variation of the QBO period originates in the upper stratosphere, where the solar-ozone radiative influence is strong. The solar modulation of the QBO period is found to be nonstationary; the averaged effect cannot be determined unless the data record is much longer. In shorter records, the correlation can change sign, as we have found in segments of the longest record available, with or without lag.

Scale Height variations with solar cycle in the ionosphere of Mars

NASA Astrophysics Data System (ADS)

Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Milan, Stephen E.; Hall, Benjamin E. S.; Cartacci, Marco; Radicella, Sandro M.; Blelly, Pierre-Louis

2015-04-01

The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on board the Mars Express spacecraft has been probing the topside of the ionosphere of Mars since June 2005, covering currently almost one solar cycle. A good knowledge of the behaviour of the ionospheric variability for a whole solar period is essential since the ionosphere is strongly dependent on solar activity. Using part of this dataset, covering the years 2005 - 2012, differences in the shape of the topside electron density profiles have been observed. These variations seem to be linked to changes in the ionospheric temperature due to the solar cycle variation. In particular, Mars' ionospheric response to the extreme solar minimum between end-2007 and end-2009 followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to internal origin of the magnetic field between both planets. Plasma parameters such as the scale height as a function of altitude, the main peak characteristics (altitude, density), the total electron content (TEC), the temperatures, and the ionospheric thermal pressures show variations related to the solar cycle. The main changes in the topside ionosphere are detected during the period of very low solar minimum, when ionospheric cooling occurs. The effect on the scale height is analysed in detail. In contrast, a clear increase of the scale height is observed during the high solar activity period due to enhanced ionospheric heating. The scale height variation during the solar cycle has been empirically modelled. The results have been compared with other datasets such as radio-occultation and retarding potential analyser data from old missions, especially in low solar activity periods (e.g. Mariner 4, Viking 1 and 2 landers), as well as with numerical modelling.

Small GSH-Capped CuInS2 Quantum Dots: MPA-Assisted Aqueous Phase Transfer and Bioimaging Applications.

PubMed

Zhao, Chuanzhen; Bai, Zelong; Liu, Xiangyou; Zhang, Yijia; Zou, Bingsuo; Zhong, Haizheng

2015-08-19

An efficient ligand exchange strategy for aqueous phase transfer of hydrophobic CuInS2/ZnS quantum dots was developed by employing glutathione (GSH) and mercaptopropionic acid (MPA) as the ligands. The whole process takes less than 20 min and can be scaled up to gram amount. The material characterizations show that the final aqueous soluble samples are solely capped with GSH on the surface. Importantly, these GSH-capped CuInS2/ZnS quantum dots have small size (hydrodynamic diameter <10 nm), moderate fluorescent properties (up to 34%) as well as high stability in aqueous solutions (stable for more than three months in 4 °C without any significant fluorescence quenching). Moreover, this ligand exchange strategy is also versatile for the aqueous phase transfer of other hydrophobic quantum dots, for instance, CuInSe2 and CdSe/ZnS quantum dots. We further demonstrated that GSH-capped quantum dots could be suitable fluorescence markers to penetrate cell membrane and image the cells. In addition, the GSH-capped CuInS2 quantum dots also have potential use in other fields such as photocatalysis and quantum dots sensitized solar cells.

Intense uniform precipitation of low-energy electrons over the polar cap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, C.; Kroehl, H.W.

1977-06-01

Analysis of precipitating electron data from the Defense Meteorological Satellite Program (DMSP) revealed significant enhancements (as large as two orders of magnitude) over the quiet time level of the low-energy electron flux over the polar cap during magnetic storms in September and October 1974. Strong asymmetry between the two polar caps was observed, and it may indicate that these electrons are of interplanetary (i.e., solar) origin and that their entry is influenced by the interplanetary magnetic field as illustrated by Yeager and Frank (1976) and Fennell et al., (1975). Energy spectra showing the spatial and temporal variations of the phenomenamore » are presented. There also is a region between the equatorward edge of the polar cap enhancement and the poleward edge of the evening auroral precipitation in which the electron flux drops down to the background level. If the observed intense polar cap precipitation is indeed of interplanetary origin, this void region implies that the poleward boundary of the auroral precipitation does not coincide with the equatorward boundary of the open field lines and that their separation cna be as wide as a few degrees in latitude.« less

Technical and economic feasibility study of solar/fossil hybrid power systems

NASA Technical Reports Server (NTRS)

Bloomfield, H. S.; Calogeras, J. E.

1977-01-01

Results show that new hybrid systems utilizing fossil fuel augmentation of solar energy can provide significant capital and energy cost benefits when compared with solar thermal systems requiring thermal storage. These benefits accrue from a reduction of solar collection area that results from both the use of highly efficient gas and combined cycle energy conversion subsystems and elimination of the requirement for long-term energy storage subsystems. Technical feasibility and fuel savings benefits of solar hybrid retrofit to existing fossil-fired, gas and vapor cycle powerplants was confirmed; however, economic viability of steam cycle retrofit was found to be dependent on the thermodynamic and operational characteristics of the existing powerplant.

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.

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.

Energy comparison between solar thermal power plant and photovoltaic power plant

NASA Astrophysics Data System (ADS)

Novosel, Urška; Avsec, Jurij

2017-07-01

The combined use of renewable energy and alternative energy systems and better efficiency of energy devices is a promising approach to reduce effects due to global warming in the world. On the basis of first and second law of thermodynamics we could optimize the processes in the energy sector. The presented paper shows the comparison between solar thermal power plant and photovoltaic power plant in terms of energy, exergy and life cycle analysis. Solar thermal power plant produces electricity with basic Rankine cycle, using solar tower and solar mirrors to produce high fluid temperature. Heat from the solar system is transferred by using a heat exchanger to Rankine cycle. Both power plants produce hydrogen via electrolysis. The paper shows the global efficiency of the system, regarding production of the energy system.

Importance of the Annual Cycles of SST and Solar Irradiance for Circulation and Rainfall: A Climate Model Simulation Study

NASA Technical Reports Server (NTRS)

Sud, Yogesh C.; Lau, William K. M.; Walker, G. K.; Mehta, V. M.

2001-01-01

Annual cycle of climate and precipitation is related to annual cycle of sunshine and sea-surface temperatures. Understanding its behavior is important for the welfare of humans worldwide. For example, failure of Asian monsoons can cause widespread famine and grave economic disaster in the subtropical regions. For centuries meteorologists have struggled to understand the importance of the summer sunshine and associated heating and the annual cycle of sea-surface temperatures (SSTs) on rainfall in the subtropics. Because the solar income is pretty steady from year to year, while SSTs depict large interannual variability as consequence of the variability of ocean dynamics, the influence of SSTs on the monsoons are better understood through observational and modeling studies whereas the relationship of annual rainfall to sunshine remains elusive. However, using NASA's state of the art climate model(s) that can generate realistic climate in a computer simulation, one can answer such questions. We asked the question: if there was no annual cycle of the sunshine (and its associated land-heating) or the SST and its associated influence on global circulation, what will happen to the annual cycle of monsoon rains? By comparing the simulation of a 4-year integration of a baseline Control case with two parallel anomaly experiments: 1) with annual mean solar and 2) with annual mean sea-surface temperatures, we were able to draw the following conclusions: (1) Tropical convergence zone and rainfall which moves with the Sun into the northern and southern hemispheres, specifically over the Indian, African, South American and Australian regions, is strongly modulated by the annual cycles of SSTs as well as solar forcings. The influence of the annual cycle of solar heating over land, however, is much stronger than the corresponding SST influence for almost all regions, particularly the subtropics; (2) The seasonal circulation patterns over the vast land-masses of the Northern Hemisphere at mid and high latitudes also get strongly influenced by the annual cycles of solar heating. The SST influence is largely limited to the oceanic regions of these latitudes; (3) The annual mode of precipitation over Amazonia has an equatorial regime revealing a maxima in the month of March associated with SST, and another maxima in the month of January associated with the solar annual cycles, respectively. The baseline simulation, which has both annual cycles, depicts both annual modes and its rainfall is virtually equal to the sum of those two modes; (4) Rainfall over Sahelian-Africa is significantly reduced (increased) in simulations lacking (invoking) solar irradiation with (without) the annual cycle. In fact, the dominant influence of solar irradiation emerges in almost all monsoonal-land regions: India, Southeast Asia, as well as Australia. The only exception is the Continental United States, where solar annual cycle shows only a relatively minor influence on the annual mode of rainfall.

Organic Dye Degradation Under Solar Irradiation by Hydrothermally Synthesized ZnS Nanospheres

NASA Astrophysics Data System (ADS)

Samanta, Dhrubajyoti; Chanu, T. Inakhunbi; Basnet, Parita; Chatterjee, Somenath

2018-02-01

The green synthesis of ZnS nanospheres using Citrus limetta (sweet lime) juice as a capping agent through a conventional hydrothermal method was studied. The particle size, morphology, chemical composition, band gap, and optical properties of the synthesized ZnS nanospheres were characterized using x-ray diffraction spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet-visible spectroscopy. The photocatalytic activity of the ZnS nanospheres was evaluated by degradation of rhodamine B (RhB) and methyl orange (MO) under solar irradiation. Upon 150 min of solar irradiation, the extent of degradation was 94% and 77% for RhB and MO, respectively.

Carrington cycle 24: the solar chromospheric emission in a historical and stellar perspective

NASA Astrophysics Data System (ADS)

Schröder, K.-P.; Mittag, M.; Schmitt, J. H. M. M.; Jack, D.; Hempelmann, A.; González-Pérez, J. N.

2017-09-01

We present the solar S-index record of cycle 24, obtained by the Telescopio Internacional de Guanajuato, Robotico Espectroscopico robotic telescope facility and its high-resolution spectrograph HEROS (R ≈ 20 000), which measures the solar chromospheric Ca II H&K line emission by using moonlight. Our calibration process uses the same set of standard stars as introduced by the Mount Wilson team, thus giving us a direct comparison with their huge body of observations taken between 1966 and 1992, as well as with other cool stars. Carrington cycle 24 activity started from the unusually deep and long minimum 2008/2009, with an S-index average of only 0.154, 0.015 deeper than the one of 1986 (〈S〉 = 0.169). In this respect, the chromospheric radiative losses differ remarkably from the variation of the coronal radio flux F10.7 cm and the sunspot numbers. In addition, the cycle 24 S-amplitude remained small, 0.022 (cycles 21 and 22 averaged: 0.024), and so resulted in a very low 2014 maximum of 〈S〉 = 0.176 (cycles 21 and 22 averaged: 0.193). We argue that this find is significant, since the Ca II H&K line emission is a good proxy for the solar far-ultraviolet (far-UV) flux, which plays an important role in the heating of the Earth's stratosphere, and we further argue that the solar far-UV flux changes with solar activity much more strongly than the total solar output.

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

SIMULATION STUDY OF HEMISPHERIC PHASE-ASYMMETRY IN THE SOLAR CYCLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukuya, D.; Kusano, K., E-mail: kusano@nagoya-u.jp

2017-01-20

Observations of the Sun suggest that solar activities systematically create north–south hemispheric asymmetries. For instance, the hemisphere in which sunspot activity is more active tends to switch after the early half of each solar cycle. Svalgaard and Kamide recently pointed out that the time gaps of polar field reversal between the northern and southern hemispheres are simply consequences of the asymmetry of sunspot activity. However, the mechanism underlying the asymmetric feature in solar cycle activity is not yet well understood. In this paper, in order to explain the cause of the asymmetry from the theoretical point of view, we investigatemore » the relationship between the dipole- and quadrupole-type components of the magnetic field in the solar cycle using the mean-field theory based on the flux transport dynamo model. As a result, we found that there are two different attractors of the solar cycle, in which either the north or the south polar field is first reversed, and that the flux transport dynamo model explains well the phase-asymmetry of sunspot activity and the polar field reversal without any ad hoc source of asymmetry.« less

Auroral-polar cap environment and its impact on spacecraft plasma interactions

NASA Technical Reports Server (NTRS)

Garrett, H. B.

1985-01-01

The high density of the plasma at shuttle altitude is likely to increase greatly the possibility of arcing and shorting of exposed high voltage surfaces. For military missions over the polar caps and through the auoroal zones, the added hazards of high energy auroral particle fluxes or solar flares will further increase the hazard to shuttle, its crew, and its mission. A review of the role that the auroral and polar cap environment play in causing these interactions was conducted. A simple, though comprehensive attempt at modelling the shuttle environment at 400 km will be described that can be used to evaluate the importance of the interactions. The results of this evaluation are then used to define areas where adequate environmental measurements will be necessary if a true spacecraft interactions technology is to be developed for the shuttle.

Detecting dust hits at Enceladus, Saturn and beyond using CAPS / ELS data from Cassini

NASA Astrophysics Data System (ADS)

Vandegriff, J. D.; Stoneberger, P. J.; Jones, G.; Waite, J. H., Jr.

2016-12-01

It has recently been shown (1) that the impact of hypervelocity dust grains on the Cassini spacecraft can be detected by the Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) instrument. For multiple Enceladus flybys, fine scale features in the lower energy regime of ELS energy spectra can be explained as short-duration, isotropic plasma clouds due to dust impacts. We have developed an algorithm for detecting these hypervelocity dust impacts, and the list of such impacts during Enceladus flybys will be presented. We also present preliminary results obtained when using the algorithm to search for dust impacts in other regions of Saturn's magnetosphere as well as in the solar wind. (1) Jones, Geraint, Hypervelocity dust impact signatures detected by Cassini CAPS-ELS in the Enceladus plume, MOP Meeting, June 1-5, 2015, Atlanta, GA

Highly improved passivation of c-Si surfaces using a gradient i a-Si:H layer

NASA Astrophysics Data System (ADS)

Lee, Soonil; Ahn, Jaehyun; Mathew, Leo; Rao, Rajesh; Zhang, Zhongjian; Kim, Jae Hyun; Banerjee, Sanjay K.; Yu, Edward T.

2018-04-01

Surface passivation using intrinsic a-Si:H (i a-Si:H) films plays a key role in high efficiency c-Si heterojunction solar cells. In this study, we demonstrate improved passivation quality using i a-Si:H films with a gradient-layered structure consisting of interfacial, transition, and capping layers deposited on c-Si surfaces. The H2 dilution ratio (R) during deposition was optimized individually for the interfacial and capping layers, which were separated by a transition layer for which R changed gradually between its values for the interfacial and capping layers. This approach yielded a significant reduction in surface carrier recombination, resulting in improvement of the minority carrier lifetime from 1480 μs for mono-layered i a-Si:H passivation to 2550 μs for the gradient-layered passivation approach.

Review of the Two-Step H2O/CO2-Splitting Solar Thermochemical Cycle Based on Zn/ZnO Redox Reactions

PubMed Central

Loutzenhiser, Peter G.; Meier, Anton; Steinfeld, Aldo

2010-01-01

This article provides a comprehensive overview of the work to date on the two‑step solar H2O and/or CO2 splitting thermochemical cycles with Zn/ZnO redox reactions to produce H2 and/or CO, i.e., synthesis gas—the precursor to renewable liquid hydrocarbon fuels. The two-step cycle encompasses: (1) The endothermic dissociation of ZnO to Zn and O2 using concentrated solar energy as the source for high-temperature process heat; and (2) the non-solar exothermic oxidation of Zn with H2O/CO2 to generate H2/CO, respectively; the resulting ZnO is then recycled to the first step. An outline of the underlying science and the technological advances in solar reactor engineering is provided along with life cycle and economic analyses. PMID:28883361

Solar Activity Across the Scales: From Small-Scale Quiet-Sun Dynamics to Magnetic Activity Cycles

NASA Technical Reports Server (NTRS)

Kitiashvili, Irina N.; Collins, Nancy N.; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A.

2017-01-01

Observations as well as numerical and theoretical models show that solar dynamics is characterized by complicated interactions and energy exchanges among different temporal and spatial scales. It reveals magnetic self-organization processes from the smallest scale magnetized vortex tubes to the global activity variation known as the solar cycle. To understand these multiscale processes and their relationships, we use a two-fold approach: 1) realistic 3D radiative MHD simulations of local dynamics together with high resolution observations by IRIS, Hinode, and SDO; and 2) modeling of solar activity cycles by using simplified MHD dynamo models and mathematical data assimilation techniques. We present recent results of this approach, including the interpretation of observational results from NASA heliophysics missions and predictive capabilities. In particular, we discuss the links between small-scale dynamo processes in the convection zone and atmospheric dynamics, as well as an early prediction of Solar Cycle 25.

Long dance of the bashful ballerina

NASA Astrophysics Data System (ADS)

Hiltula, T.; Mursula, K.

2006-02-01

In this letter we extend our earlier analysis of the north-south asymmetry of the heliospheric current sheet (HCS) using a recent data set of heliospheric magnetic field (HMF) sector polarities extracted from ground-based magnetic observations. We find that the heliospheric current sheet is similarly southward coned or shifted during the late declining to minimum phase of the solar cycle in the early part of the studied data interval (1926-1955), as earlier found for the more recent solar cycles. Accordingly, the HCS has been southward shifted; that is, the solar ballerina has been bashful at least during the last 80 years. We also discuss solar cycle 19 which presents a period of a very curious behaviour for the HCS with an exceptionally large HMF toward sector dominance in 1957, the year of cycle 19 maximum, and an equally strong HMF away sector dominance in 1960, the time of final solar polarity reversal.

Simulated space environment tests on cadmium sulfide solar cells

NASA Technical Reports Server (NTRS)

Clarke, D. R.; Oman, H.

1971-01-01

Cadmium sulfide (Cu2s - CdS) solar cells were tested under simulated space environmental conditions. Some cells were thermally cycled with illumination from a Xenon-arc solar simulator. A cycle was one hour of illumination followed immediately with one-half hour of darkness. In the light, the cells reached an equilibrium temperature of 60 C (333 K) and in the dark the cell temperature dropped to -120 C (153 K). Other cells were constantly illuminated with a Xenon-arc solar simulator. The equilibrium temperature of these cells was 55 C (328 K). The black vacuum chamber walls were cooled with liquid nitrogen to simulate a space heat sink. Chamber pressure was maintained at 0.000001 torr or less. Almost all of the solar cells tested degraded in power when exposed to a simulated space environment of either thermal cycling or constant illumination. The cells tested the longest were exposed to 10.050 thermal cycles.

Solar activity across the scales: from small-scale quiet-Sun dynamics to magnetic activity cycles

NASA Astrophysics Data System (ADS)

Kitiashvili, I.; Collins, N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A.

2017-12-01

Observations as well as numerical and theoretical models show that solar dynamics is characterized by complicated interactions and energy exchanges among different temporal and spatial scales. It reveals magnetic self-organization processes from the smallest scale magnetized vortex tubes to the global activity variation known as the solar cycle. To understand these multiscale processes and their relationships, we use a two-fold approach: 1) realistic 3D radiative MHD simulations of local dynamics together with high-resolution observations by IRIS, Hinode, and SDO; and 2) modeling of solar activity cycles by using simplified MHD dynamo models and mathematical data assimilation techniques. We present recent results of this approach, including the interpretation of observational results from NASA heliophysics missions and predictive capabilities. In particular, we discuss the links between small-scale dynamo processes in the convection zone and atmospheric dynamics, as well as an early prediction of Solar Cycle 25.

Reinforcement of double dynamo waves as a source of solar activity and its prediction on millennium timescale

NASA Astrophysics Data System (ADS)

Popova, E.; Zharkova, V. V.; Shepherd, S. J.; Zharkov, S.

2016-12-01

Using the principal components of solar magnetic field variations derived from the synoptic maps for solar cycles 21-24 with Principal Components Analysis (PCA) (Zharkova et al, 2015) we confirm our previous prediction of the upcoming Maunder minimum to occur in cycles 25-27, or in 2020-2055. We also use a summary curve of the two eigen vectors of solar magnetic field oscillations (or two dynamo waves) to extrapolate solar activity backwards to the three millennia and to compare it with relevant historic and Holocene data. Extrapolation of the summary curve confirms the eight grand cycles of 350-400-years superimposed on 22 year-cycles caused by beating effect of the two dynamo waves generated in the two (deep and shallow) layers of the solar interior. The grand cycles in different periods comprise a different number of individual 22-year cycles; the longer the grand cycles the larger number of 22 year cycles and the smaller their amplitudes. We also report the super-grand cycle of about 2000 years often found in solas activity with spectral analysis. Furthermore, the summary curve reproduces a remarkable resemblance to the sunspot and terrestrial activity reported in the past: the recent Maunder Minimum (1645-1715), Dalton minimum (1790-1815), Wolf minimum (1200), Homeric minimum (800-900 BC), the Medieval Warmth Period (900-1200), the Roman Warmth Period (400-10BC) and so on. Temporal variations of these dynamo waves are modelled with the two layer mean dynamo model with meridional circulation revealing a remarkable resemblance of the butterfly diagram to the one derived for the last Maunder minimum in 17 century and predicting the one for the upcoming Maunder minimum in 2020-2055.

Ag2S Quantum Dot-Sensitized Solar Cells by First Principles: The Effect of Capping Ligands and Linkers.

PubMed

Amaya Suárez, Javier; Plata, Jose J; Márquez, Antonio M; Fernández Sanz, Javier

2017-09-28

Quantum dots solar cells, QDSCs, are one of the candidates for being a reliable alternative to fossil fuels. However, the well-studied CdSe and CdTe-based QDSCs present a variety of issues for their use in consumer-goods applications. Silver sulfide, Ag 2 S, is a promising material, but poor efficiency has been reported for QDSCs based on this compound. The potential influence of each component of QDSCs is critical and key for the development of more efficient devices based on Ag 2 S. In this work, density functional theory calculations were performed to study the nature of the optoelectronic properties for an anatase-TiO 2 (101) surface sensitized with different silver sulfide nanoclusters. We demonstrated how it is possible to deeply tune of its electronic properties by modifying the capping ligands and linkers to the surface. Finally, an analysis of the electron injection mechanism for this system is presented.

NASA Discovery Program Workshop

NASA Technical Reports Server (NTRS)

1992-01-01

The purpose of the workshop was to review concepts for Discover-class missions that would follow the first two missions (MESUR-Pathfinder and NEAR) of this new program. The concepts had been generated by scientists involved in NASA's Solar System Exploration Program to carry out scientifically important investigations within strict guidelines -- $150 million cap on development cost and 3 year cap on development schedule. Like the Astrophysics Small Explorers (SMEX), such 'faster and cheaper' missions could provide vitality to solar system exploration research by returning high quality data more frequently and regularly and by involving many more young researchers than normally participate directly in larger missions. An announcement of opportunity (AO) to propose a Discovery mission to NASA is expected to be released in about two years time. One purpose of the workshop was to assist Code SL in deciding how to allocate its advanced programs resources. A second, complimentary purpose was to provide the concept proposers with feedback to allow them to better prepare for the AO.

Structural, optical and photovoltaic properties of co-doped CdTe QDs for quantum dots sensitized solar cells

NASA Astrophysics Data System (ADS)

Ayyaswamy, Arivarasan; Ganapathy, Sasikala; Alsalme, Ali; Alghamdi, Abdulaziz; Ramasamy, Jayavel

2015-12-01

Zinc and sulfur alloyed CdTe quantum dots (QDs) sensitized TiO2 photoelectrodes have been fabricated for quantum dots sensitized solar cells. Alloyed CdTe QDs were prepared in aqueous phase using mercaptosuccinic acid (MSA) as a capping agent. The influence of co-doping on the structural property of CdTe QDs was studied by XRD analysis. The enhanced optical absorption of alloyed CdTe QDs was studied using UV-vis absorption and fluorescence emission spectra. The capping of MSA molecules over CdTe QDs was confirmed by the FTIR and XPS analyses. Thermogravimetric analysis confirms that the prepared QDs were thermally stable up to 600 °C. The photovoltaic performance of alloyed CdTe QDs sensitized TiO2 photoelectrodes were studied using J-V characteristics under the illumination of light with 1 Sun intensity. These results show the highest photo conversion efficiency of η = 1.21%-5% Zn & S alloyed CdTe QDs.

Construction of a century solar chromosphere data set for solar activity related research

NASA Astrophysics Data System (ADS)

Lin, Ganghua; Wang, Xiao Fan; Yang, Xiao; Liu, Suo; Zhang, Mei; Wang, Haimin; Liu, Chang; Xu, Yan; Tlatov, Andrey; Demidov, Mihail; Borovik, Aleksandr; Golovko, Aleksey

2017-06-01

This article introduces our ongoing project "Construction of a Century Solar Chromosphere Data Set for Solar Activity Related Research". Solar activities are the major sources of space weather that affects human lives. Some of the serious space weather consequences, for instance, include interruption of space communication and navigation, compromising the safety of astronauts and satellites, and damaging power grids. Therefore, the solar activity research has both scientific and social impacts. The major database is built up from digitized and standardized film data obtained by several observatories around the world and covers a time span of more than 100 years. After careful calibration, we will develop feature extraction and data mining tools and provide them together with the comprehensive database for the astronomical community. Our final goal is to address several physical issues: filament behavior in solar cycles, abnormal behavior of solar cycle 24, large-scale solar eruptions, and sympathetic remote brightenings. Significant signs of progress are expected in data mining algorithms and software development, which will benefit the scientific analysis and eventually advance our understanding of solar cycles.

[Suppression of cycling activity in sheep using parenteral progestagen treatment].

PubMed

Janett, F; Camponovo, L; Lanker, U; Hässig, M; Thun, R

2004-03-01

The objective of this study was to evaluate the effect of two synthetic progestagen preparations Chlormadinone acetate (CAP, Chronosyn, Veterinaria AG Zürich) and Medroxyprogesterone acetate (MPA, Nadigest, G Streuli & Co. Uznach) on cycling activity and fertility in sheep. A flock of 28 non pregnant white alpine sheep was randomly divided into three groups, A (n = 10), B (n = 9) and C (n = 9). During a period of 4 weeks the cycling activity was confirmed by blood progesterone analysis. Thereafter, the animals of group A were treated with 50 mg CAP, those of group B with 140 mg MPA and those of group C with physiological saline solution. All injections were given intramuscularly. Suppression of endogenous progesterone secretion lasted from 28 to 49 days (mean = 39 days) in group A and from 42 to 70 days (mean = 50 days) in group B. The synchronization effect of both preparations was unsatisfactory as the occurrence of first estrus was distributed over a period of 3 weeks in group A and 4 weeks in group B. These findings could also be confirmed by the lambing period which lasted 52 days in group A and 36 days in group B. Control animals lambed within 9 days due to the synchronizing effect of the ram. The first fertile estrus was observed 36 days (group A) and 45 days (group B) after the treatment. In group A all 10 animals and in groups B and C 8 of 9 ewes each became pregnant. Parenteral progestagen application with CAP and MPA is a simple, safe and reversible method of estrus suppression in the sheep. The minimal suppressive duration of 4 (CAP) and 5 weeks (MPA) is not sufficient when a period of 3 months (alpine pasture period) is desired.

Use of life cycle assessments to evaluate the environmental footprint of contaminated sediment remediation.

PubMed

Sparrevik, Magnus; Saloranta, Tuomo; Cornelissen, Gerard; Eek, Espen; Fet, Annik Magerholm; Breedveld, Gijs D; Linkov, Igor

2011-05-15

Ecological and human risks often drive the selection of remedial alternatives for contaminated sediments. Traditional human and ecological risk assessment (HERA) includes assessing risk for benthic organisms and aquatic fauna associated with exposure to contaminated sediments before and after remediation as well as risk for human exposure but does not consider the environmental footprint associated with implementing remedial alternatives. Assessment of environmental effects over the whole life cycle (i.e., Life Cycle Assessment, LCA) could complement HERA and help in selecting the most appropriate sediment management alternative. Even though LCA has been developed and applied in multiple environmental management cases, applications to contaminated sediments and marine ecosystems are in general less frequent. This paper implements LCA methodology for the case of the polychlorinated dibenzo-p-dioxins and -furans (PCDD/F)-contaminated Grenland fjord in Norway. LCA was applied to investigate the environmental footprint of different active and passive thin-layer capping alternatives as compared to natural recovery. The results showed that capping was preferable to natural recovery when analysis is limited to effects related to the site contamination. Incorporation of impacts related to the use of resources and energy during the implementation of a thin layer cap increase the environmental footprint by over 1 order of magnitude, making capping inferior to the natural recovery alternative. Use of biomass-derived activated carbon, where carbon dioxide is sequestered during the production process, reduces the overall environmental impact to that of natural recovery. The results from this study show that LCA may be a valuable tool for assessing the environmental footprint of sediment remediation projects and for sustainable sediment management.

Application of solar energy to air conditioning systems

NASA Technical Reports Server (NTRS)

Nash, J. M.; Harstad, A. J.

1976-01-01

The results of a survey of solar energy system applications of air conditioning are summarized. Techniques discussed are both solar powered (absorption cycle and the heat engine/Rankine cycle) and solar related (heat pump). Brief descriptions of the physical implications of various air conditioning techniques, discussions of status, proposed technological improvements, methods of utilization and simulation models are presented, along with an extensive bibliography of related literature.

Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965-2014

NASA Astrophysics Data System (ADS)

Modzelewska, R.; Alania, M. V.

2018-01-01

Aims: We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965-2014 (almost five solar cycles, cycles 20-24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods: We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal ( 24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results: We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

Solar Cycle Variability and Grand Minima Induced by Joy's Law Scatter

NASA Astrophysics Data System (ADS)

Karak, Bidya Binay; Miesch, Mark S.

2017-08-01

The strength of the solar cycle varies from one cycle to another in an irregular manner and the extreme example of this irregularity is the Maunder minimum when Sun produced only a few spots for several years. We explore the cause of these variabilities using a 3D Babcock--Leighton dynamo. In this model, based on the toroidal flux at the base of the convection zone, bipolar magnetic regions (BMRs) are produced with flux, tilt angle, and time of emergence all obtain from their observed distributions. The dynamo growth is limited by a tilt quenching.The randomnesses in the BMR emergences make the poloidal field unequal and eventually cause an unequal solar cycle. When observed fluctuations of BMR tilts around Joy's law, i.e., a standard deviation of 15 degrees, are considered, our model produces a variation in the solar cycle comparable to the observed solar cycle variability. Tilt scatter also causes occasional Maunder-like grand minima, although the observed scatter does not reproduce correct statistics of grand minima. However, when we double the tilt scatter, we find grand minima consistent with observations. Importantly, our dynamo model can operate even during grand minima with only a few BMRs, without requiring any additional alpha effect.

A STUDY OF THE HEMISPHERIC ASYMMETRY OF SUNSPOT AREA DURING SOLAR CYCLES 23 AND 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chowdhury, Partha; Choudhary, D. P.; Gosain, Sanjay, E-mail: partha240@yahoo.co.in, E-mail: parthares@gmail.com, E-mail: debiprasad.choudhary@csun.edu, E-mail: sgosain@nso.edu

2013-05-10

Solar activity indices vary over the Sun's disk, and various activity parameters are not considered to be symmetric between the northern and southern hemispheres of the Sun. The north-south asymmetry of different solar indices provides an important clue to understanding subphotospheric dynamics and solar dynamo action, especially with regard to nonlinear dynamo models. In the present work, we study the statistical significance of the north-south asymmetry of sunspot areas for the complete solar cycle 23 (1996-2008) and rising branch of cycle 24 (first 45 months). The preferred hemisphere in each year of cycles 23 and 24 has been identified bymore » calculating the probability of hemispheric distribution of sunspot areas. The statistically significant intermediate-term periodicities of the north-south asymmetry of sunspot area data have also been investigated using Lomb-Scargle and wavelet techniques. A number of short- and mid-term periods including the best-known Rieger one (150-160 days) are detected in cycle 23 and near Rieger-type periods during cycle 24, and most of them are found to be time variable. We present our results and discuss their possible explanations with the help of theoretical models and observations.« less

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.

In situ analysis of capacity fade in thin-film anodes for high performance Li-ion all-solid-state batteries

NASA Astrophysics Data System (ADS)

Leite, Marina S.; Gong, Chen; Ruzmetov, Dmitry; Talin, A. Alec

There is still a pressing need to understand how the solid-interfaces in Li-ion all-solid-batteries form, including their chemical composition and electrical characteristics. In order to resolve the origin of the degradation mechanism in Al anodes, we combine in situ scanning electron microscopy in ultra-high vacuum with electrochemical cycling, in addition to ex situ characterization of the morphological, chemical, and electrical changes of the Al anodes upon lithiation. An AlLi alloy capped by a stable Al-Li-O is formed on the top surface of the anode, trapping Li, which results in the capacity fade, from 48.0 to 41.5 μ.Ah/cm2 in two cycles. The addition of a Cu capping layer is insufficient to prevent the device degradation because of the fast Li diffusion within Al. Yet, Si present extremely stable cycling: >92% of capacity retention after 100 cycles, with average Coulombic efficiency of 98%. Our in situ measurements represent a new platform for probing the real-time degradation of electrodes in all-solid-state batteries for energy storage devices.

Solar-powered air-conditioning

NASA Technical Reports Server (NTRS)

Clark, D. C.; Rousseau, J.

1977-01-01

Report focuses on recent study on development of solar-powered residential air conditioners and is based on selected literature through 1975. Its purposes are to characterize thermal and mechanical systems that might be useful in development of Rankine-cycle approach to solar cooling and assessment of a Lithium Bromide/Water absorption cycle system.

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...

Cap-independent translation of plant viral RNAs

PubMed Central

Pettit Kneller, Elizabeth L.; Rakotondrafara, Aurélie M.; Miller, W. Allen

2007-01-01

The RNAs of many plant viruses lack a 5′ cap and must be translated by a cap-independent mechanism. Here, we discuss the remarkably diverse cap-independent translation elements that have been identified in members of the Potyviridae, Luteoviridae, and Tombusviridae families, and genus Tobamovirus. Many other plant viruses have uncapped RNAs but their translation control elements are uncharacterized. Cap-independent translation elements of plant viruses differ strikingly from those of animal viruses: they are smaller (<200 nt), some are located in the 3′ untranslated region, some require ribosome scanning from the 5′ end of the mRNA, and the 5′ UTR elements are much less structured than those of animal viruses. We discuss how these elements may interact with host translation factors, and speculate on their mechanism of action and their roles in the virus replication cycle. Much remains to be learned about how these elements enable plant viruses to usurp the host translational machinery. PMID:16360925

TWO NOVEL PARAMETERS TO EVALUATE THE GLOBAL COMPLEXITY OF THE SUN'S MAGNETIC FIELD AND TRACK THE SOLAR CYCLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L.; Landi, E.; Gibson, S. E., E-mail: lzh@umich.edu

2013-08-20

Since the unusually prolonged and weak solar minimum between solar cycles 23 and 24 (2008-2010), the sunspot number is smaller and the overall morphology of the Sun's magnetic field is more complicated (i.e., less of a dipole component and more of a tilted current sheet) compared with the same minimum and ascending phases of the previous cycle. Nearly 13 yr after the last solar maximum ({approx}2000), the monthly sunspot number is currently only at half the highest value of the past cycle's maximum, whereas the polar magnetic field of the Sun is reversing (north pole first). These circumstances make itmore » timely to consider alternatives to the sunspot number for tracking the Sun's magnetic cycle and measuring its complexity. In this study, we introduce two novel parameters, the standard deviation (SD) of the latitude of the heliospheric current sheet (HCS) and the integrated slope (SL) of the HCS, to evaluate the complexity of the Sun's magnetic field and track the solar cycle. SD and SL are obtained from the magnetic synoptic maps calculated by a potential field source surface model. We find that SD and SL are sensitive to the complexity of the HCS: (1) they have low values when the HCS is flat at solar minimum, and high values when the HCS is highly tilted at solar maximum; (2) they respond to the topology of the HCS differently, as a higher SD value indicates that a larger part of the HCS extends to higher latitude, while a higher SL value implies that the HCS is wavier; (3) they are good indicators of magnetically anomalous cycles. Based on the comparison between SD and SL with the normalized sunspot number in the most recent four solar cycles, we find that in 2011 the solar magnetic field had attained a similar complexity as compared to the previous maxima. In addition, in the ascending phase of cycle 24, SD and SL in the northern hemisphere were on the average much greater than in the southern hemisphere, indicating a more tilted and wavier HCS in the north than the south, associated with the early reversal of the polar magnetic field in the north relative to the south.« less

Fifteen years in the high-energy life of the solar-type star HD 81809. XMM-Newton observations of a stellar activity cycle

NASA Astrophysics Data System (ADS)

Orlando, S.; Favata, F.; Micela, G.; Sciortino, S.; Maggio, A.; Schmitt, J. H. M. M.; Robrade, J.; Mittag, M.

2017-09-01

Context. The modulation of the activity level of solar-like stars is commonly revealed by cyclic variations in their chromospheric indicators, such as the Ca II H&K S-index, similarly to what is observed in our Sun. However, while the variation of solar activity is also reflected in the cyclical modulation of its coronal X-ray emission, similar behavior has only been discovered in a few stars other than the Sun. Aims: The data set of the long-term XMM-Newton monitoring program of HD 81809 is analyzed to study its X-ray cycle, investigate if the latter is related to the chromospheric cycle, infer the structure of the corona of HD 81809, and explore if the coronal activity of HD 81809 can be ascribed to phenomena similar to solar activity and, therefore, considered an extension of the solar case. Methods: We analyzed the observations of HD 81809 performed with XMM-Newton with a regular cadence of six months from 2001 to 2016, which represents one of the longest available observational baseline ( 15 yr) for a solar-like star with a well-studied chromospheric cycle (with a period of 8 yr). We investigated the modulation of coronal luminosity and temperature and its relation with the chromospheric cycle. We interpreted the data in terms of a mixture of solar-like coronal regions, adopting a method originally proposed to study the Sun as an X-ray star. Results: The observations show a well-defined regular cyclic modulation of the X-ray luminosity that reflects the activity level of HD 81809. The data covers approximately two cycles of coronal activity; the modulation has an amplitude of a factor of 5 (excluding evident flares, as in the June 2002 observation) and a period of 7.3 ± 1.5 yr, which is consistent with that of the chromospheric cycle. We demonstrate that the corona of HD 81809 can be interpreted as an extension of the solar case and can be modeled with a mixture of solar-like coronal regions along the whole cycle. The activity level is mainly determined by varying coverage of very bright active regions, similar to cores of active regions observed in the Sun. Evidence of unresolved significant flaring activity is present especially in the proximity of cycle maxima.

42 years of continuous observations of the Solar 1 diameter from 1974 to 2015 - What do they forecast.

NASA Astrophysics Data System (ADS)

Humberto Andrei, Alexandre; Penna, Jucira; Boscardin, Sergio; Papa, Andres R. R.; Garcia, Marcos Antonio; Sigismondi, Costantino

2016-07-01

Several research groups in the world developed observational programs for the Sun in order to measure its apparent diameter over time with dedicated instruments, called solar astrolabes, since 1974. Their data have been gathered in several observing stations connected in the R2S3 (Réseau de Suivi au Sol du Rayon Solaire) network and through reciprocal visits and exchanges: Nice/Calern Observatoire/France, Rio de Janeiro Observatório Nacional/Brazil, Observatório de São Paulo IAGUSP/Brazil, Observatório Abrahão de Moraes IAGUSP/Brazil, Antalya Observatory/Turkey, San Fernando/Spain. Since all the optics and data treatment of the solar astrolabes was the same, from the oldest, with a single fixed objective prism, to the newest, with an angle variable objective prism and digital image acquisition, their results could be put together. Each instrument had its own density filter with a prismatic effect responsible for a particular shift. Thus, identical data gathering and just a different prismatic shift, enabled to reconcile all those series by using the common stretches and derive a single additive constant to place each one onto a common average. By doing so, although the value itself of the ground observed solar diameter is lost, its variations are determined over 35 years. On the combined series of the ground observed solar diameter a modulation with the 11 years main solar cycle is evident. However when such modulation is removed, both from the solar diameter compound series and from the solar activity series (as given by the sunspots count), a very strong anticorrelation is revealed. This suggested a larger diameter for the forthcoming cycles. This was very well verified for solar cycle 23, and correctly forecasted for cycle 24,in a behavior similar to that on the Minima of Dalton and Maunder. The ground monitoring keeps being routinely followed at Observatório Nacional in Rio de Janeiro, now using the Solar Heliometer, specially built to this end . The Heliometer has the same focal length and aperture of the earlier solar astrolabes, and the diameter determination uses the same physical and mathematical definition of the solar limb. Therefore the same robust, no-hypothesis, simple combination by an adding constant, can be used to include the Heliometer measurements along the previous long, continuous series. As a result the series of measurements of the variation of the solar diameter reaches 42 years, and covers also the solar cycle 24. In this paper we review all the individual series chief elements, as well as the calculation and values of the adding constants. We show the earlier comparison that lead to an anticorrelation at 0.867 to the solar activity record, when the 11 years modulation is expurgate, and exhibits an impressively accurate description of cycle 23. On the strength of such successful analysis we employ the new longer series to discuss the current solar cycle 24 and forecast for the following solar cycle 25. We thus advocate in favor of continued and continuous ground measurements of the solar diameter, on the usefulness of making these results available to the scientific community at large, and on the matter-of-fact, real variations of the solar diameter on long term time periods and/or local places on the Sun, in this case possibly associated to major magnetism driven solar transients.

Solar Cycle Variations of SABER CO2 and MLS H2O in the Mesosphere and Lower Thermosphere Region

NASA Astrophysics Data System (ADS)

Salinas, C. C. J.; Chang, L. C.; Liang, M. C.; Qian, L.; Yue, J.; Russell, J. M., III; Mlynczak, M. G.

2017-12-01

This work aims to present the solar cycle variations of SABER CO2 and MLS H2O in the Mesosphere and Lower Thermosphere region. These observations are then compared to SD-WACCM outputs of CO2 and H2O in order to understand their physical mechanisms. After which, we attempt to model their solar cycle variations using the default TIME-GCM and the TIME-GCM with MERRA reanalysis as lower-boundary conditions. Comparing the outputs of the default TIME-GCM and TIME-GCM with MERRA will give us insight into the importance of solar forcing and lower atmospheric forcing on the solar cycle variations of CO2 and H2O. The solar cycle influence in the parameters are calculated by doing a multiple linear regression with the F10.7 index. The solar cycle of SABER CO2 is reliable above 1e-2 mb and below 1e-3 mb. Preliminary results from the observations show that SABER CO2 has a stronger negative anomaly due to the solar cycle over the winter hemisphere. MLS H2O is reliable until 1e-2. Preliminary results from the observations show that MLS H2O also has a stronger negative anomaly due to the solar cycle over the winter hemisphere. Both SD-WACCM and the default TIME-GCM reproduce these stronger anomalies over the winter hemisphere. An analysis of the tendency equations in SD-WACCM and default TIME-GCM then reveal that for CO2, the stronger winter anomaly may be attributed to stronger downward transport over the winter hemisphere. For H2O, an analysis of the tendency equations in SD-WACCM reveal that the stronger winter anomaly may be attributed to both stronger downward transport and stronger photochemical loss. On the other hand, in the default TIME-GCM, the stronger winter anomaly in H2O may only be attributed to stronger downward transport. For both models, the stronger downward transport is attributed to enhanced stratospheric polar winter jet during solar maximum. Future work will determine whether setting the lower boundary conditions of TIME-GCM with MERRA will improve the match between TIME-GCM and SD-WACCM. Also, with the TIME-GCM outputs, the influence of these MLT circulation changes on the ionospheric winter anomaly will be determined.

The combined effects of eustasy, tectonism, and clastic influx on the development of Pennsylvanian cyclic carbonates, southern Sangre de Cristo Mountains, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong Shouyeh; Humphrey, J.D.

1991-03-01

Pennsylvania cyclothems are well documented on stable continental shelves and the cyclicity has generally been attributed to glacio-eustasy. As a contrast, Atokan-Desmoinesian cyclic carbonates of the southern Sangre de Cristo Mountains developed in a tectonically active foreland basin, formed by thrusting along the Picuris-Pecos fault during early Pennsylvanian time. Strata exposed in two sections (Dalton Bluff, 260 m; Johnson Mesa, 340 m) are characterized by (1) shallowing-upward cycles, (2) cycles of variable thickness (5-20 m), (3) incomplete cycles, (4) cycles interrupted by terrigenous clastic input, and (5) noncyclic intervals. Allocyclic mechanisms alone cannot fully explain these observations; the authors hereinmore » propose that a complex interplay among eustasy, tectonism, and clastic sediment supply were responsible for the observed cycles. Lithofacies analysis indicates that location within the foreland basin played a significant role in cycle attributes. In the deeper portions of the basin (e.g., Dalton Bluff), an idealized cycle, from base to top consists of (1) shale/marl facies, (2) brachiopod wackestone facies, (3) phylloid algal facies, and (4) marine clastic facies. No evidence for subaerial exposure of cycle caps is noted. In contrast, in shallow portions of the basin near the forebulge (e.g., Johnson Mesa) the marine clastic facies is substituted by crinoidal grainstone/packstone facies that is capped by subaerial exposure surface. Each of the two cycles displays an overall grand (lower order) shallowing-upward cycle. This grand cycle developed as sediments infilled the initially starved foreland basin.« less

Temporal Variability of Atomic Hydrogen From the Mesopause to the Upper Thermosphere

NASA Astrophysics Data System (ADS)

Qian, Liying; Burns, Alan G.; Solomon, Stan S.; Smith, Anne K.; McInerney, Joseph M.; Hunt, Linda A.; Marsh, Daniel R.; Liu, Hanli; Mlynczak, Martin G.; Vitt, Francis M.

2018-01-01

We investigate atomic hydrogen (H) variability from the mesopause to the upper thermosphere, on time scales of solar cycle, seasonal, and diurnal, using measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, and simulations by the National Center for Atmospheric Research Whole Atmosphere Community Climate Model-eXtended (WACCM-X). In the mesopause region (85 to 95 km), the seasonal and solar cycle variations of H simulated by WACCM-X are consistent with those from SABER observations: H density is higher in summer than in winter, and slightly higher at solar minimum than at solar maximum. However, mesopause region H density from the Mass-Spectrometer-Incoherent-Scatter (National Research Laboratory Mass-Spectrometer-Incoherent-Scatter 00 (NRLMSISE-00)) empirical model has reversed seasonal variation compared to WACCM-X and SABER. From the mesopause to the upper thermosphere, H density simulated by WACCM-X switches its solar cycle variation twice, and seasonal dependence once, and these changes of solar cycle and seasonal variability occur in the lower thermosphere ( 95 to 130 km), whereas H from NRLMSISE-00 does not change solar cycle and seasonal dependence from the mesopause through the thermosphere. In the upper thermosphere (above 150 km), H density simulated by WACCM-X is higher at solar minimum than at solar maximum, higher in winter than in summer, and also higher during nighttime than daytime. The amplitudes of these variations are on the order of factors of 10, 2, and 2, respectively. This is consistent with NRLMSISE-00.

Projecting the potential impact of the Cap-Score™ on clinical pregnancy, live births, and medical costs in couples with unexplained infertility.

PubMed

Babigumira, Joseph B; Sharara, Fady I; Garrison, Louis P

2018-01-01

The Cap-Score™ was developed to assess the capacitation status of men, thereby enabling personalized management of unexplained infertility by choosing timed intrauterine insemination (IUI), versus immediate in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) in individuals with a low Cap-Score™. The objective of this study was to estimate the differences in outcomes and costs comparing the use of the Cap-Score™ with timed IUI (CS-TI) and the standard of care (SOC), which was assumed to be three IUI cycles followed by three IVF-ICSI cycles. We developed and parameterized a decision-analytic model of management of unexplained infertility for women based on data from the published literature. We calculated the clinical pregnancy rates, live birth rates, and medical costs comparing CS-TI and SOC. We used Monte Carlo simulation to quantify uncertainty in projected estimates and performed univariate sensitivity analysis. Compared to SOC, CS-TI was projected to increase the pregnancy rate by 1-26%, marginally reduce live birth rates by 1-3% in couples with women below 40 years, increase live birth rates by 3-7% in couples with women over 40 years, reduce mean medical costs by $4000-$19,200, reduce IUI costs by $600-$1370, and reduce IVF costs by $3400-$17,800, depending on the woman's age. The Cap-Score™ is a potentially valuable clinical tool for management of unexplained infertility because it is projected to improve clinical pregnancy rates, save money, and, depending on the price of the test, increase access to treatment for infertility.

Solar Cycle Dependence of the Diurnal Anisotropy of 0.6 TeV Cosmic-ray Intensity Observed with the Matsushiro Underground Muon Detector

NASA Astrophysics Data System (ADS)

Munakata, K.; Mizoguchi, Y.; Kato, C.; Yasue, S.; Mori, S.; Takita, M.; Kóta, J.

2010-04-01

We analyze the temporal variation of the diurnal anisotropy of sub-TeV cosmic-ray intensity observed with the Matsushiro (Japan) underground muon detector over two full solar activity cycles in 1985-2008. We find an anisotropy component in the solar diurnal anisotropy superimposed on the Compton-Getting anisotropy due to Earth's orbital motion around the Sun. The phase of this additional anisotropy is almost constant at ~15:00 local solar time corresponding to the direction perpendicular to the average interplanetary magnetic field at Earth's orbit, while the amplitude varies between a maximum (0.043% ± 0.002%) and minimum (~0.008% ± 0.002%) in a clear correlation with the solar activity. We find a significant time lag between the temporal variations of the amplitude and the sunspot number (SSN) and obtain the best correlation coefficient of +0.74 with the SSN delayed for 26 months. We suggest that this anisotropy might be interpreted in terms of the energy change due to the solar-wind-induced electric field expected for galactic cosmic rays (GCRs) crossing the wavy neutral sheet. The average amplitude of the sidereal diurnal variation over the entire period is 0.034% ± 0.003%, which is roughly one-third of the amplitude reported from air shower and deep-underground muon experiments monitoring multi-TeV GCR intensity suggesting a significant attenuation of the anisotropy due to the solar modulation. We find, on the other hand, only a weak positive correlation between the sidereal diurnal anisotropy and the solar activity cycle in which the amplitude in the "active" solar activity epoch is about twice the amplitude in the "quiet" solar activity epoch. This implies that only one-fourth of the total attenuation varies in correlation with the solar activity cycle and/or the solar magnetic cycle. We finally examine the temporal variation of the "single-band valley depth" (SBVD) quoted by the Milagro experiment and, in contrast with recent Milagro's report, we find no steady increase in the Matsushiro observations in a seven-year period between 2000 and 2007. We suggest, therefore, that the steady increase of the SBVD reported by the Milagro experiment is not caused by the decreasing solar modulation in the declining phase of the 23rd solar activity cycle.

The MSFC Solar Activity Future Estimation (MSAFE) Model

NASA Technical Reports Server (NTRS)

Suggs, Ron

2017-01-01

The Natural Environments Branch of the Engineering Directorate at Marshall Space Flight Center (MSFC) provides solar cycle forecasts for NASA space flight programs and the aerospace community. These forecasts provide future statistical estimates of sunspot number, solar radio 10.7 cm flux (F10.7), and the geomagnetic planetary index, Ap, for input to various space environment models. For example, many thermosphere density computer models used in spacecraft operations, orbital lifetime analysis, and the planning of future spacecraft missions require as inputs the F10.7 and Ap. The solar forecast is updated each month by executing MSAFE using historical and the latest month's observed solar indices to provide estimates for the balance of the current solar cycle. The forecasted solar indices represent the 13-month smoothed values consisting of a best estimate value stated as a 50 percentile value along with approximate +/- 2 sigma values stated as 95 and 5 percentile statistical values. This presentation will give an overview of the MSAFE model and the forecast for the current solar cycle.

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.

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.

Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

NASA Astrophysics Data System (ADS)

Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean, earthquakes and etc). The study was supported by a grant of RFBR, n 06-05-64998.

Signature of a possible relationship between the maximum CME speed index and the critical frequencies of the F1 and F2 ionospheric layers: Data analysis for a mid-latitude ionospheric station during the solar cycles 23 and 24

NASA Astrophysics Data System (ADS)

Kilcik, Ali; Ozguc, Atila; Yiǧit, Erdal; Yurchyshyn, Vasyl; Donmez, Burcin

2018-06-01

We analyze temporal variations of two solar indices, the monthly mean Maximum CME Speed Index (MCMESI) and the International Sunspot Number (ISSN) as well as the monthly median ionospheric critical frequencies (foF1, and foF2) for the time period of 1996-2013, which covers the entire solar cycle 23 and the ascending branch of the cycle 24. We found that the maximum of foF1 and foF2 occurred respectively during the first and second maximum of the ISSN solar activity index in the solar cycle 23. We compared these data sets by using the cross-correlation and hysteresis analysis and found that both foF1 and foF2 show higher correlation with ISSN than the MCMESI during the investigated time period, but when significance levels are considered correlation coefficients between the same indices become comparable. Cross-correlation analysis showed that the agreement between these data sets (solar indices and ionospheric critical frequencies) is better pronounced during the ascending phases of solar cycles, while they display significant deviations during the descending phase. We conclude that there exists a signature of a possible relationship between MCMESI and foF1 and foF2, which means that MCMESI could be used as a possible indicator of solar and geomagnetic activity, even though other investigations are needed.

Technology for Bayton-cycle powerplants using solar and nuclear energy

NASA Technical Reports Server (NTRS)

English, R. E.

1986-01-01

Brayton cycle gas turbines have the potential to use either solar heat or nuclear reactors for generating from tens of kilowatts to tens of megawatts of power in space, all this from a single technology for the power generating system. Their development for solar energy dynamic power generation for the space station could be the first step in an evolution of such powerplants for a very wide range of applications. At the low power level of only 10 kWe, a power generating system has already demonstrated overall efficiency of 0.29 and operated 38 000 hr. Tests of improved components show that these components would raise that efficiency to 0.32, a value twice that demonstrated by any alternate concept. Because of this high efficiency, solar Brayton cycle power generators offer the potential to increase power per unit of solar collector area to levels exceeding four times that from photovoltaic powerplants using present technology for silicon solar cells. The technologies for solar mirrors and heat receivers are reviewed and assessed. This Brayton technology for solar powerplants is equally suitable for use with the nuclear reactors. The available long time creep data on the tantalum alloy ASTAR-811C show that such Brayton cycles can evolve to cycle peak temperatures of 1500 K (2240 F). And this same technology can be extended to generate 10 to 100 MW in space by exploiting existing technology for terrestrial gas turbines in the fields of both aircraft propulsion and stationary power generation.

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.

Water Cycling in the North Polar Region of Mars

NASA Technical Reports Server (NTRS)

Tamppari, L. K.; Smith, M. D.; Bass, D. S.

2003-01-01

To date, there has been no comprehensive study to understand the partitioning of water into vapor and ice clouds, and the associated effects of dust and surface temperature in the north polar region. Ascertaining the degree to which water is transported out of the cap region versus within the cap region will give much needed insight into the overall story of water cycling on a seasonal basis. In particular, understanding the mechanism for the polar cap surface albedo changes would go along way in comprehending the sources and sinks of water in the northern polar region. We approach this problem by examining Thermal Emission Spectrometer (TES) atmospheric and surface data acquired in the northern summer season and comparing it to Viking data when possible. Because the TES instrument spans the absorption bands of water vapor, water ice, dust, and measures surface temperature, all three aerosols and surface temperature can be retrieved simultaneously. This presentation will show our latest results on the water vapor, water-ice clouds seasonal and spatial distributions, as well as surface temperatures and dust distribution which may lend insight into where the water is going.

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.

Long-term Trends in the Solar Wind Proton Measurements

NASA Astrophysics Data System (ADS)

Elliott, Heather A.; McComas, David J.; DeForest, Craig E.

2016-11-01

We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (T p) and speed (V p) and between the proton density (n p) and speed using OMNI solar wind observations taken near Earth. We find a long-term decrease in the proton temperature-speed (T p-V p) slope that lasted from 1972 to 2010, but has been trending upward since 2010. Since the solar wind proton density-speed (n p-V p) relationship is not linear like the T p-V p relationship, we perform power-law fits for n p-V p. The exponent (steepness in the n p-V p relationship) is correlated with the solar cycle. This exponent has a stronger correlation with current sheet tilt angle than with sunspot number because the sunspot number maxima vary considerably from cycle to cycle and the tilt angle maxima do not. To understand this finding, we examined the average n p for different speed ranges, and found that for the slow wind n p is highly correlated with the sunspot number, with a lag of approximately four years. The fast wind n p variation was less, but in phase with the cycle. This phase difference may contribute to the n p-V p exponent correlation with the solar cycle. These long-term trends are important since empirical formulas based on fits to T p and V p data are commonly used to identify interplanetary coronal mass ejections, but these formulas do not include any time dependence. Changes in the solar wind density over a solar cycle will create corresponding changes in the near-Earth space environment and the overall extent of the heliosphere.

Modulation of galactic cosmic rays in solar cycles 22-24: Analysis and physical interpretation

NASA Astrophysics Data System (ADS)

Kalinin, M. S.; Bazilevskaya, G. A.; Krainev, M. B.; Svirzhevskaya, A. K.; Svirzhevsky, N. S.; Starodubtsev, S. A.

2017-09-01

This work represents a physical interpretation of cosmic ray modulation in the 22nd-24th solar cycles, including an interpretation of an unusual behavior of their intensity in the last minimum of the solar activity (2008-2010). In terms of the Parker modulation model, which deals with regularly measured heliospheric characteristics, it is shown that the determining factor of the increased intensity of the galactic cosmic rays in the minimum of the 24th solar cycle is an anomalous reduction of the heliospheric magnetic field strength during this time interval under the additional influence of the solar wind velocity and the tilt angle of the heliospheric current sheet. We have used in the calculations the dependence of the diffusion tensor on the rigidity in the form K ij ∝ R 2-μ with μ = 1.2 in the sector zones of the heliospheric magnetic field and with μ = 0.8 outside the sector zones, which leads to an additional amplification of the diffusion mechanism of cosmic ray modulation. The proposed approach allows us to describe quite satisfactorily the integral intensity of protons with an energy above 0.1 GeV and the energy spectra in the minima of the 22nd-24th solar cycles at the same value of the free parameter. The determining factor of the anomalously high level of the galactic cosmic ray intensity in the minimum of the 24th solar cycle is the significant reduction of the heliospheric magnetic field strength during this time interval. The forecast of the intensity level in the minimum of the 25th solar cycle is provided.

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

NASA Astrophysics Data System (ADS)

Virtanen, I. I.; Mursula, K.

2009-04-01

We compare the open solar magnetic field estimated by the PFSS model based on the WSO photospheric field observations, with the inner heliospheric magnetic field. We trace the observed radial HMF into the coronal PFSS boundary at 2.5 solar radii using the observed solar wind velocity, and determine the PFSS model field at the line-of-sight footpoint. Comparing the two field values, we calculate the power n of the apparent decrease of the radial field. According to expectations based on Maxwell's equations, also reproduced by Parker's HMF model, the radial HMF field should decrease with n=2. However, comparison gives considerably lower values of n, indicating the effect of HCS in the PFSS model and the possible superexpansion. The n values vary with solar cycle, being roughly 1.3-1.4 at minima and about 1.7 at maxima. Interestingly, the n values for the two HMF sectors show systematic differences in the late declining to minimum phase, with smaller n values for the HMF sector dominant in the northern hemisphere. This is in agreement with the smaller field value in the northern hemisphere and the southward shifted HCS, summarized by the concept of the bashful ballerina. We also find that the values of n during the recent years, in the late declining phase of solar cycle 23, are significantly larger than during the same phase of the previous cycles. This agrees with the exceptionally large tilt of the solar dipole at the end of cycle 23. We also find that the bashful ballerina appears even during SC 23 but the related hemispheric differences are smaller than during the previous cycles.

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

EPA Science Inventory

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

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

Hemispheric Coupling: Comparing Dynamo Simulations and Observations

NASA Astrophysics Data System (ADS)

Norton, A. A.; Charbonneau, P.; Passos, D.

2014-12-01

Numerical simulations that reproduce solar-like magnetic cycles can be used to generate long-term statistics. The variations in north-south hemispheric solar cycle synchronicity and amplitude produced in simulations has not been widely compared to observations. The observed limits on solar cycle amplitude and phase asymmetry show that hemispheric sunspot area production is no more than 20 % asymmetric for cycles 17-23 and that phase lags do not exceed 20 % (or two years) of the total cycle period, as determined from Royal Greenwich Observatory sunspot data. Several independent studies have found a long-term trend in phase values as one hemisphere leads the other for, on average, four cycles. Such persistence in phase is not indicative of a stochastic phenomenon. We compare these observational findings to the magnetic cycle found in a numerical simulation of solar convection recently produced with the EULAG-MHD model. This long "millennium simulation" spans more than 1600 years and generated 40 regular, sunspot-like cycles. While the simulated cycle length is too long (˜40 yrs) and the toroidal bands remain at too high of latitudes (>30°), some solar-like aspects of hemispheric asymmetry are reproduced. The model is successful at reproducing the synchrony of polarity inversions and onset of cycle as the simulated phase lags do not exceed 20 % of the cycle period. The simulated amplitude variations between the north and south hemispheres are larger than those observed in the Sun, some up to 40 %. An interesting note is that the simulations also show that one hemisphere can persistently lead the other for several successive cycles, placing an upper bound on the efficiency of transequatorial magnetic coupling mechanisms. These include magnetic diffusion, cross-equatorial mixing within latitudinally-elongated convective rolls (a.k.a. "banana cells") and transequatorial meridional flow cells. One or more of these processes may lead to magnetic flux cancellation whereby the oppositely directed fields come in close proximity and cancel each other across the magnetic equator late in the solar cycle. We discuss the discrepancies between model and observations and the constraints they pose on possible mechanisms of hemispheric coupling.

Solar cycle variation of Mars exospheric temperatures: Critical review of available dayside measurements and recent model simulations

NASA Astrophysics Data System (ADS)

Bougher, Stephen; Huestis, David

The responses of the Martian dayside thermosphere to solar flux variations (on both solar rotation and solar cycle timescales) have been the subject of considerable debate and study for many years. Available datasets include: Mariner 6,7,9 (UVS dayglow), Viking Lander 1-2 (UAMS densities upon descent), several aerobraking campaigns (MGS, Odyssey, MRO densities), and Mars Express (SPICAM dayglow). Radio Science derived plasma scale heights near the ionospheric peak can be used to derive neutral temperatures in this region (only); such values are not applicable to exobase heights (e.g. Forbes et al. 2008; Bougher et al. 2009). Recently, densities and temperatures derived from precise orbit determination of the MGS spacecraft (1999-2005) have been used to establish the responses of Mars' exosphere to long-term solar flux variations (Forbes et al., 2008). From this multi-year dataset, dayside exospheric temperatures weighted toward moderate southern latitudes are found to change by about 120 K over the solar cycle. However, the applicability of these drag derived exospheric temperatures to near solar minimum conditions is suspect (e.g Bruinsma and Lemoine, 2002). Finally, re-evaluation of production mechanisms for UV dayglow emissions implies revised values for exospheric temperatures (e.g. Simon et al., 2009; Huestis et al. 2010). Several processes are known to influence Mars' exospheric temperatures and their variability (Bougher et al., 1999; 2000; 2009). Solar EUV heating and its variations with solar fluxes received at Mars, CO2 15-micron cooling, molecular thermal conduction, and hydrodynamic heating/cooling associated with global dynamics all contribute to regulate dayside thermo-spheric temperatures. Poorly measured dayside atomic oxygen abundances render CO2 cooling rates uncertain at the present time. However, global thermospheric circulation models can be exercised for conditions spanning the solar cycle and Mars seasons to address the relative roles of these processes in driving observed variations in dayside exospheric temperatures. Mars Thermospheric General Circulation Model (MTGCM) simulations and resulting exo-spheric temperatures will be presented and compared with assimilated temperatures collected from all these available measurements over the solar cycle. It is important to match measure-ments at dayside local times and latitudes for specific seasons with corresponding MTGCM simulated outputs. Calculated local heat budgets and their variations illustrate the changes required to reproduce solar cycle variations in exospheric temperatures. The ability to success-fully predict solar cycle responses of the Martian upper atmosphere is important for simulations of present-day Mars volatile escape rates.

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.

Influence of Solar Variability on the North Atlantic / European Sector.

NASA Astrophysics Data System (ADS)

Gray, L. J.

2016-12-01

The 11year solar cycle signal in December-January-February averaged mean-sea-level pressure and Atlantic/European blocking frequency is examined using multilinear regression with indices to represent variability associated with the solar cycle, volcanic eruptions, the El Nino - Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO). Results from a previous 11-year solar cycle signal study of the period 1870-2010 (140 years; 13 solar cycles) that suggested a 3-4 year lagged signal in SLP over the Atlantic are confirmed by analysis of a much longer reconstructed dataset for the period 1660-2010 (350 years; 32 solar cycles). Apparent discrepancies between earlier studies are resolved and stem primarily from the lagged nature of the response and differences between early- and late-winter responses. Analysis of the separate winter months provide supporting evidence for two mechanisms of influence, one operating via the atmosphere that maximises in late winter at 0-2 year lags and one via the mixd-layer ocean that maximises in early winter at 3-4 year lags. Corresponding analysis of DJF-averaged Atlantic / European blocking frequency shows a highly statistically significant signal at 1-year lag that originates promarily from the late winter response. The 11-year solar signal in DJF blocking frequency is compared with other known influences from ENSO and the AMO and found to be as large in amplitude and have a larger region of statistical significance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, N. B.; Qu, Z. N., E-mail: znqu@ynao.ac.cn

The ensemble empirical mode decomposition (EEMD) analysis is utilized to extract the intrinsic mode functions (IMFs) of the solar mean magnetic field (SMMF) observed at the Wilcox Solar Observatory of Stanford University from 1975 to 2014, and then we analyze the periods of these IMFs as well as the relation of IMFs (SMMF) with some solar activity indices. The two special rotation cycles of 26.6 and 28.5 days should be derived from different magnetic flux elements in the SMMF. The rotation cycle of the weak magnetic flux element in the SMMF is 26.6 days, while the rotation cycle of themore » strong magnetic flux element in the SMMF is 28.5 days. The two rotation periods of the structure of the interplanetary magnetic field near the ecliptic plane are essentially related to weak and strong magnetic flux elements in the SMMF, respectively. The rotation cycle of weak magnetic flux in the SMMF did not vary over the last 40 years because the weak magnetic flux element derived from the weak magnetic activity on the full disk is not influenced by latitudinal migration. Neither the internal rotation of the Sun nor the solar magnetic activity on the disk (including the solar polar fields) causes the annual variation of SMMF. The variation of SMMF at timescales of a solar cycle is more related to weak magnetic activity on the full solar disk.« less

Solar Variability from 240 to 1750 nm in Terms of Faculae Brightening and Sunspot Darkening from SCIAMACHY

NASA Astrophysics Data System (ADS)

Pagaran, J.; Weber, M.; Burrows, J.

2009-08-01

The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

SOLAR VARIABILITY FROM 240 TO 1750 nm IN TERMS OF FACULAE BRIGHTENING AND SUNSPOT DARKENING FROM SCIAMACHY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagaran, J.; Weber, M.; Burrows, J.

2009-08-01

The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variationsmore » above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.« less

Solar Energetic Particle Composition over Two Solar Cycles as Observed by the Ulysses/HISCALE and ACE/EPAM Pulse Height Analyzers.

NASA Astrophysics Data System (ADS)

Patterson, J. D.; Madanian, H.; Manweiler, J. W.; Lanzerotti, L. J.

2017-12-01

We present the compositional variation in the Solar Energetic Particle (SEP) population in the inner heliosphere over two solar cycles using data from the Ulysses Heliospheric Instrument for Spectra, Composition, and Anisotropy at Low Energies (HISCALE) and Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM). The Ulysses mission was active from late 1990 to mid-2009 in a heliopolar orbit inclined by 80° with a perihelion of 1.3 AU and an aphelion of 5.4 AU. The ACE mission has been active since its launch in late 1997 and is in a halo orbit about L1. These two missions provide a total of 27 years of continuous observation in the inner heliosphere with twelve years of simultaneous observation. HISCALE and EPAM data provide species-resolved differential flux and density of SEP between 0.5-5 MeV/nuc. Several ion species (He, C, O, Ne, Si, Fe) are identified using the Pulse Height Analyzer (PHA) system of the Composition Aperture for both instruments. The He density shows a noticeable increase at high solar activity followed by a moderate drop at the quiet time of the solar minimum between cycles 23 and 24. The density of heavier ions (i.e. O and Fe) change minimally with respect to the F10.7 index variations however, certain energy-specific count rates decrease during solar minimum. With Ulysses and ACE observing in different regions of the inner heliosphere, there are significant latitudinal differences in how the O/He ratios vary with the solar cycle. At solar minimum, there is reasonable agreement between the observations from both instruments. At solar max 23, the differences in composition over the course of the solar cycle, and as observed at different heliospheric locations can provide insight to the origins of and acceleration processes differentially affecting solar energetic ions.

Polar cap contraction and expansion during a period of substorms

NASA Astrophysics Data System (ADS)

Aikio, Anita; Pitkänen, Timo; Honkonen, Ilja; Palmroth, Minna; Amm, Olaf

We have studied the variations in the polar cap area and related parameters during a period of four substorms on February 18, 2004, following an extended quiet period. The measurements were obtained by the EISCAT incoherent scatter radars, MIRACLE magnetometers, Geotail and solar wind satellites. In addition, the event is modeled by the GUMICS-4 MHD simulation. By using the measured and modeled data, the dayside and nightside reconnection voltages are calculated. The results show a good general agreement in the polar cap boundary (PCB) location as estimated by the EISCAT radars and the GUMICS simulation. Deviations are found, too, like shorter durations of expansion phases in the simulation. Geotail measurements of the inclination angle of the magnetic field in the tail (Xgsm= -22 Re) agree with the PCB latitude variations measured by EISCAT at a different MLT. We conclude that a large polar cap corresponds to a stretched tail configuration in the near-Earth tail and a small polar cap to a more dipolar configuration. The substorm onsets took place during southward IMF. A specific feature is that the substorm expansion phases were not associated with significant contractions of the polar cap. Even though nightside reconnection voltages started to increase during expansion phases, maximum closure of open flux took place in the recovery phases. We shortly discuss implications of the observation to the definition of the recovery phase.

Polar Cap Plasma and Convection

NASA Technical Reports Server (NTRS)

Elliott, Heather A.; Craven, Paul D.; Comfort, Richard H.; Chandler, Michael O.; Moore, Thomas E.; Ruohoniemi, J. M.

1998-01-01

This presentation will describe the character of the polar cap plasma in 10% AGU Spring 1998 particular the convection velocities at the perigee (about 1.8 Re) and apogee( about 8.9 Re) of Polar in relationship to Interplanetary Magnetic Field (IMF) and solar wind parameters. This plasma is thought to be due to several sources; the polar wind, cleft ion fountain, and auroral outflow. The plasma in the polar cap tends to be mostly field-aligned. At any given point in the polar cap, this plasma could be from a different regions since convection of magnetic field lines can transport this material. it is quite difficult to study such a phenomena with single point measurements. Current knowledge of the polar cap plasma obtained by in situ measurements will be presented along with recent results from the Polar mission. This study also examines the direct electrical coupling between the magnetosphere and ionosphere by comparing convection velocities measured by the Thermal Ion Dynamics Experiment (TIDE) and Magnetic Field Experiment (MFE) instruments in magnetosphere and measurements of the ionosphere by ground-based radars. At times such a comparison is difficult because the Polar satellite at apogee spends a large amount of time in the polar cap which is a region that is not coverage well by the current SuperDam coherent radars. This is impart due to the lack of irregularities that returns the radar signal.

Reduction of Life Cycle CO2 Emission in Public Welfare Facilities Equipped with PV/Solar Heat/Cogeneration System

NASA Astrophysics Data System (ADS)

Oke, Shinichiro; Kemmoku, Yoshishige; Takikawa, Hirofumi; Sakakibara, Tateki

The reduction effect of life cycle CO2 emission is examined in case of introducing a PV/solar heat/cogeneration system into public welfare facilities(hotel and hospital). Life cycle CO2 emission is calculated as the sum of that when operating and that when manufacturing equipments. The system is operated with the dynamic programming method, into which hourly data of electric and heat loads, solar insolation, and atmospheric temperature during a year are input. The proposed system is compared with a conventional system and a cogeneration system. The life cycle CO2 emission of the PV/solar heat/cogeneration system is lower than that of the conventional system by 20% in hotel and by 14% in hospital.

Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25

NASA Astrophysics Data System (ADS)

Miyake, Shoko; Kataoka, Ryuho; Sato, Tatsuhiko

2017-04-01

Weak solar activity and high cosmic ray flux during the coming solar cycle are qualitatively anticipated by the recent observations that show the decline in the solar activity levels. We predict the cosmic ray modulation and resultant radiation exposure at flight altitude by using the time-dependent and three-dimensional model of the cosmic ray modulation. Our galactic cosmic ray (GCR) model is based on the variations of the solar wind speed, the strength of the heliospheric magnetic field, and the tilt angle of the heliospheric current sheet. We reproduce the 22 year variation of the cosmic ray modulation from 1980 to 2015 taking into account the gradient-curvature drift motion of GCRs. The energy spectra of GCR protons obtained by our model show good agreement with the observations by the Balloon-borne Experiment with a Superconducting magnetic rigidity Spectrometer (BESS) and the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) except for a discrepancy at the solar maximum. Five-year annual radiation dose around the solar minimum at the solar cycle 24/25 will be approximately 19% higher than that in the last cycle. This is caused by the charge sign dependence of the cosmic ray modulation, such as the flattop profiles in a positive polarity.

Coronal Holes and Magnetic Flux Ropes Interweaving Solar Cycles

NASA Astrophysics Data System (ADS)

Lowder, Chris; Yeates, Anthony; Leamon, Robert; Qiu, Jiong

2016-10-01

Coronal holes, dark patches observed in solar observations in extreme ultraviolet and x-ray wavelengths, provide an excellent proxy for regions of open magnetic field rooted near the photosphere. Through a multi-instrument approach, including SDO data, we are able to stitch together high resolution maps of coronal hole boundaries spanning the past two solar activity cycles. These observational results are used in conjunction with models of open magnetic field to probe physical solar parameters. Magnetic flux ropes are commonly defined as bundles of solar magnetic field lines, twisting around a common axis. Photospheric surface flows and magnetic reconnection work in conjunction to form these ropes, storing magnetic stresses until eruption. With an automated methodology to identify flux ropes within observationally driven magnetofrictional simulations, we can study their properties in detail. Of particular interest is a solar-cycle length statistical description of eruption rates, spatial distribution, magnetic orientation, flux, and helicity. Coronal hole observations can provide useful data about the distribution of the fast solar wind, with magnetic flux ropes yielding clues as to ejected magnetic field and the resulting space weather geo-effectiveness. With both of these cycle-spanning datasets, we can begin to form a more detailed picture of the evolution and consequences of both sets of solar magnetic features.

Solar causes of strong geomagnetic disturbances during the period 1996—2013

NASA Astrophysics Data System (ADS)

Hejda, Pavel; Bochníček, Josef; Valach, Fridrich; Revallo, Miloš

2017-04-01

The purpose of this research is to assess the contribution of CMEs and CIRs to geomagnetic activity during the period 1996—2013, covering the 23rd solar cycle, the solar minimum between the 23rd and the 24th solar cycles as well as the ascending part of the current 24th solar cycle. Both CMEs and CIRs are capable of driving significant space weather effects on the Earth. Current study is not primarily aimed at construction of prediction models but can contribute to this topic by answering two principal questions: (1) what is the contribution of CME and CIR type solar events to various levels of geomagnetic disturbances and how it varies during the solar cycle (2) how does the successive emergence of CME and CIR events influence the geomagnetic response. Sometimes it can be difficult to assign the response to a particular event properly, especially in the case of several successive events. We noticed that the CIRs appeared to play important role also in years when strongly geoeffective CMEs occurred. An interesting finding, which we have revealed on this subject, concerned the year 2009; then the extremely low geomagnetic activity was probably caused by very slow solar wind from coronal holes along with the rare occurrences of CIRs.

Solar activity simulation and forecast with a flux-transport dynamo

NASA Astrophysics Data System (ADS)

Macario-Rojas, Alejandro; Smith, Katharine L.; Roberts, Peter C. E.

2018-06-01

We present the assessment of a diffusion-dominated mean field axisymmetric dynamo model in reproducing historical solar activity and forecast for solar cycle 25. Previous studies point to the Sun's polar magnetic field as an important proxy for solar activity prediction. Extended research using this proxy has been impeded by reduced observational data record only available from 1976. However, there is a recognised need for a solar dynamo model with ample verification over various activity scenarios to improve theoretical standards. The present study aims to explore the use of helioseismology data and reconstructed solar polar magnetic field, to foster the development of robust solar activity forecasts. The research is based on observationally inferred differential rotation morphology, as well as observed and reconstructed polar field using artificial neural network methods via the hemispheric sunspot areas record. Results show consistent reproduction of historical solar activity trends with enhanced results by introducing a precursor rise time coefficient. A weak solar cycle 25, with slow rise time and maximum activity -14.4% (±19.5%) with respect to the current cycle 24 is predicted.

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.

Single-step colloidal quantum dot films for infrared solar harvesting

NASA Astrophysics Data System (ADS)

Kiani, Amirreza; Sutherland, Brandon R.; Kim, Younghoon; Ouellette, Olivier; Levina, Larissa; Walters, Grant; Dinh, Cao-Thang; Liu, Mengxia; Voznyy, Oleksandr; Lan, Xinzheng; Labelle, Andre J.; Ip, Alexander H.; Proppe, Andrew; Ahmed, Ghada H.; Mohammed, Omar F.; Hoogland, Sjoerd; Sargent, Edward H.

2016-10-01

Semiconductors with bandgaps in the near- to mid-infrared can harvest solar light that is otherwise wasted by conventional single-junction solar cell architectures. In particular, colloidal quantum dots (CQDs) are promising materials since they are cost-effective, processed from solution, and have a bandgap that can be tuned into the infrared (IR) via the quantum size effect. These characteristics enable them to harvest the infrared portion of the solar spectrum to which silicon is transparent. To date, IR CQD solar cells have been made using a wasteful and complex sequential layer-by-layer process. Here, we demonstrate ˜1 eV bandgap solar-harvesting CQD films deposited in a single step. By engineering a fast-drying solvent mixture for metal iodide-capped CQDs, we deposited active layers greater than 200 nm in thickness having a mean roughness less than 1 nm. We integrated these films into infrared solar cells that are stable in air and exhibit power conversion efficiencies of 3.5% under illumination by the full solar spectrum, and 0.4% through a simulated silicon solar cell filter.

Long-term variation of radar-auroral backscatter and the interplanetary sector structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeoman, T.K.; Burrage, M.D.; Lester, M.

Recurrent variation of geomagnetic activity at the {approximately}27-day solar rotation period and higher harmonics is a well-documented phenomenon. Auroral radar backscatter data from the Sweden and Britain Radar-Auroral Experiment (SABRE) radar provide a continuous time series from 1981 to the present which is a highly sensitive monitor of geomagnetic activity. In this study, Maximum Entropy Method (MEM) dynamic power spectra of SABRE backscatter data from 1981 to 1989, concurrent interplanetary magnetic field (IMF) and solar wind parameters from 1981 to 1987, and the Kp index since 1932 are examined. Data since 1977 are compared with previously published heliospheric current sheetmore » measurements mapped out from the solar photosphere. Stong periodic behavior is observed in the radar backscatter during the declining phase of solar cycle 21, but this periodicity disappears at the start of solar cycle 22. Similar behavior is observed in earlier solar cycles in the Kp spectra. Details of the radar backscatter, IMF, and solar wind spectra indicate that the solar wind momentum density is the dominant parameter in determining the backscatter periodicity. The temporal evolution of two- and four-sector structures, as predicted by SABRE backscatter spectra, throughout solar cycle 21 generally still agree well with heliospheric current sheet measurements. For one interval, however, there is evidence that evolution of the current sheet has occurred between the photospheric source surface and the Earth.« less

Preserving a Unique Archive for Long-Term Solar Variability Studies

NASA Astrophysics Data System (ADS)

Webb, David F.; Hewins, Ian; McFadden, Robert; Emery, Barbara; Gibson, Sarah; Denig, William

2016-05-01

In 1964 (solar cycle 20) Patrick McIntosh began creating hand-drawn synoptic maps of solar activity, based on Hydrogen alpha (Hα) imaging measurements. These synoptic maps were unique because they traced the polarity inversion lines (PILs), connecting widely separated filaments, fibril patterns and plage corridors to reveal the large-scale organization of the solar magnetic field. He and his assistants later included coronal hole (CH) boundaries to the maps, usually from ground-based He-I 10830 images. They continued making these maps until 2010 (the start of solar cycle 24), yielding more than 40 years (~ 540 Carrington rotations) or nearly four complete solar cycles (SCs) of synoptic maps. The McIntosh collection of maps forms a unique and consistent set of global solar magnetic field data, and are unique tools for studying the structure and evolution of the large-scale solar fields and polarity boundaries, because: 1) they have excellent spatial resolution for defining polarity boundaries, 2) the organization of the fields into long-lived, coherent features is clear, and 3) the data are relatively homogeneous over four solar cycles. After digitization and archiving, these maps -- along with computer codes permitting efficient searches of the map arrays -- will be made publicly available at NOAA’s National Centers for Environmental Information (NCEI) in their final, searchable form. This poster is a progress report of the project so far and some suggested scientific applications.

The radial distribution of cosmic rays in the heliosphere at solar maximum

NASA Astrophysics Data System (ADS)

McDonald, F. B.; Fujii, Z.; Heikkila, B.; Lal, N.

2003-08-01

To obtain a more detailed profile of the radial distribution of galactic (GCRs) and anomalous (ACRs) cosmic rays, a unique time in the 11-year solar activity cycle has been selected - that of solar maximum. At this time of minimum cosmic ray intensity a simple, straight-forward normalization technique has been found that allows the cosmic ray data from IMP 8, Pioneer 10 (P-10) and Voyagers 1 and 2 (V1, V2) to be combined for the solar maxima of cycles 21, 22 and 23. This combined distribution reveals a functional form of the radial gradient that varies as G 0/r with G 0 being constant and relatively small in the inner heliosphere. After a transition region between ˜10 and 20 AU, G 0 increases to a much larger value that remains constant between ˜25 and 82 AU. This implies that at solar maximum the changes that produce the 11-year modulation cycle are mainly occurring in the outer heliosphere between ˜15 AU and the termination shock. These observations are not inconsistent with the concept that Global Merged Interaction. regions (GMIRs) are the principal agent of modulation between solar minimum and solar maximum. There does not appear to be a significant change in the amount of heliosheath modulation occurring between the 1997 solar minimum and the cycle 23 solar maximum.

Cassini observations of carbon-based anions in Titan's ionosphere

NASA Astrophysics Data System (ADS)

Desai, Ravindra; Lewis, Gethyn; Waite, J. Hunter; Kataria, Dhiren; Wellbrock, Anne; Jones, Geraint; Coates, Andrew

2016-07-01

Cassini observations of Titan's ionosphere revealed an atmosphere rich in positively and negatively charged ions and organic molecules. The detection of large quantities of negatively charged ions was particularly surprising and adds Titan to the growing list of locations where anion chemistry has been observed to play an important role. In this study we present updated analysis on these negatively charged ions through an enhanced understanding of the Cassini CAPS Electron Spectrometer (CAPS-ELS) instrument response. The ionisation of Titan's dominant atmospheric constituent, N2, by the HeII Solar line, results in an observable photoelectron population at 24.1eV which we use to correct for differential spacecraft charging. Correcting for further energy-angle signatures within this dataset, we use an updated fitting procedure to show how the ELS mass spectrum, previously grouped into broad mass ranges, can be resolved into specific peaks at multiples of carbon-based anion species up to over 100amu/q. These peaks are shown to be ubiquitous within Titan's upper atmosphere and reminiscent of carbon-based anions identified in dense molecular clouds beyond our Solar System. It is thus shown how the moon Titan in the Outer Solar System can be used as an analogue to study these even more remote and exotic astrophysical environments.

New Space Weather Systems Under Development and Their Contribution to Space Weather Management

NASA Astrophysics Data System (ADS)

Tobiska, W.; Bouwer, D.; Schunk, R.; Garrett, H.; Mertens, C.; Bowman, B.

2008-12-01

There have been notable successes during the past decade in the development of operational space environment systems. Examples include the Magnetospheric Specification Model (MSM) of the Earth's magnetosphere, 2000; SOLAR2000 (S2K) solar spectral irradiances, 2001; High Accuracy Satellite Drag Model (HASDM) neutral atmosphere densities, 2004; Global Assimilation of Ionospheric Measurements (GAIM) ionosphere specification, 2006; Hakamada-Akasofu-Fry (HAF) solar wind parameters, 2007; Communication Alert and Prediction System (CAPS) ionosphere, high frequency radio, and scintillation S4 index prediction, 2008; and GEO Alert and Prediction System (GAPS) geosynchronous environment satellite charging specification and forecast, 2008. Operational systems that are in active operational implementation include the Jacchia-Bowman 2006/2008 (JB2006/2008) neutral atmosphere, 2009, and the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) aviation radiation model using the Radiation Alert and Prediction System (RAPS), 2010. U.S. national agency and commercial assets will soon reach a state where specification and prediction will become ubiquitous and where coordinated management of the space environment and space weather will become a necessity. We describe the status of the CAPS, GAPS, RAPS, and JB2008 operational development. We additionally discuss the conditions that are laying the groundwork for space weather management and estimate the unfilled needs as we move beyond specification and prediction efforts.

High-Efficiency Silicon/Organic Heterojunction Solar Cells with Improved Junction Quality and Interface Passivation.

PubMed

He, Jian; Gao, Pingqi; Ling, Zhaoheng; Ding, Li; Yang, Zhenhai; Ye, Jichun; Cui, Yi

2016-12-27

Silicon/organic heterojunction solar cells (HSCs) based on conjugated polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and n-type silicon (n-Si) have attracted wide attention due to their potential advantages of high efficiency and low cost. However, the state-of-the-art efficiencies are still far from satisfactory due to the inferior junction quality. Here, facile treatments were applied by pretreating the n-Si wafer in tetramethylammonium hydroxide (TMAH) solution and using a capping copper iodide (CuI) layer on the PEDOT:PSS layer to achieve a high-quality Schottky junction. Detailed photoelectric characteristics indicated that the surface recombination was greatly suppressed after TMAH pretreatment, which increased the thickness of the interfacial oxide layer. Furthermore, the CuI capping layer induced a strong inversion layer near the n-Si surface, resulting in an excellent field effect passivation. With the collaborative improvements in the interface chemical and electrical passivation, a competitive open-circuit voltage of 0.656 V and a high fill factor of 78.1% were achieved, leading to a stable efficiency of over 14.3% for the planar n-Si/PEDOT:PSS HSCs. Our findings suggest promising strategies to further exploit the full voltage as well as efficiency potentials for Si/organic solar cells.

The Predictability of Advection-dominated Flux-transport Solar Dynamo Models

NASA Astrophysics Data System (ADS)

Sanchez, Sabrina; Fournier, Alexandre; Aubert, Julien

2014-01-01

Space weather is a matter of practical importance in our modern society. Predictions of forecoming solar cycles mean amplitude and duration are currently being made based on flux-transport numerical models of the solar dynamo. Interested in the forecast horizon of such studies, we quantify the predictability window of a representative, advection-dominated, flux-transport dynamo model by investigating its sensitivity to initial conditions and control parameters through a perturbation analysis. We measure the rate associated with the exponential growth of an initial perturbation of the model trajectory, which yields a characteristic timescale known as the e-folding time τ e . The e-folding time is shown to decrease with the strength of the α-effect, and to increase with the magnitude of the imposed meridional circulation. Comparing the e-folding time with the solar cycle periodicity, we obtain an average estimate for τ e equal to 2.76 solar cycle durations. From a practical point of view, the perturbations analyzed in this work can be interpreted as uncertainties affecting either the observations or the physical model itself. After reviewing these, we discuss their implications for solar cycle prediction.

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.

Cross correlation and time-lag between cosmic ray intensity and solar activity during solar cycles 21, 22 and 23

NASA Astrophysics Data System (ADS)

Sierra-Porta, D.

2018-07-01

In the present paper a systematic study is carried out to validate the similarity or co-variability between daily terrestrial cosmic-ray intensity and three parameters of the solar corona evolution, i.e., the number of sunspots and flare index observed in the solar corona and the Ap index for regular magnetic field variations caused by regular solar radiation changes. The study is made for a period including three solar cycles starting with cycle 21 (year 1976) and ending on cycle 23 (year 2008). A cross-correlation analysis was used to establish patterns and dependence of the variables. This study focused on the time lag calculation for these variables and found a maximum of negative correlation over CC1≈ 0.85, CC2≈ 0.75 and CC3≈ 0.63 with an estimation of 181, 156 and 2 days of deviation between maximum/minimum of peaks for the intensity of cosmic rays related with sunspot number, flare index and Ap index regression, respectively.

Solar and terrestrial physics. [effects of solar activities on earth environment

NASA Technical Reports Server (NTRS)

1975-01-01

The effects of solar radiation on the near space and biomental earth, the upper atmosphere, and the magnetosphere are discussed. Data obtained from the OSO satellites pertaining to the solar cycle variation of extreme ultraviolet (EUV) radiation are analyzed. The effects of solar cycle variation of the characteristics of the solar wind are examined. The fluid mechanics of shock waves and the specific relationship to the characteristics of solar shock waves are investigated. The solar and corpuscular heating of the upper atmosphere is reported based on the findings of the AEROS and NATE experiments. Seasonal variations of the upper atmosphere composition are plotted based on OGO-6 mass spectrometer data.

Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

2010-01-01

Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approximately 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

Tetracycline-inducible protein expression in pancreatic cancer cells: Effects of CapG overexpression

PubMed Central

Tonack, Sarah; Patel, Sabina; Jalali, Mehdi; Nedjadi, Taoufik; Jenkins, Rosalind E; Goldring, Christopher; Neoptolemos, John; Costello, Eithne

2011-01-01

AIM: To establish stable tetracycline-inducible pancreatic cancer cell lines. METHODS: Suit-2, MiaPaca-2, and Panc-1 cells were transfected with a second generation reverse tetracycline-controlled transactivator protein (rtTA2S-M2), under the control of either a cytomegalovirus (CMV) or a chicken β-actin promoter, and the resulting clones were characterised. RESULTS: Use of the chicken (β-actin) promoter proved superior for both the production and maintenance of doxycycline-inducible cell lines. The system proved versatile, enabling transient inducible expression of a variety of genes, including GST-P, CYP2E1, S100A6, and the actin capping protein, CapG. To determine the physiological utility of this system in pancreatic cancer cells, stable inducible CapG expressors were established. Overexpressed CapG was localised to the cytoplasm and the nuclear membrane, but was not observed in the nucleus. High CapG levels were associated with enhanced motility, but not with changes to the cell cycle, or cellular proliferation. In CapG-overexpressing cells, the levels and phosphorylation status of other actin-moduating proteins (Cofilin and Ezrin/Radixin) were not altered. However, preliminary analyses suggest that the levels of other cellular proteins, such as ornithine aminotransferase and enolase, are altered upon CapG induction. CONCLUSION: We have generated pancreatic-cancer derived cell lines in which gene expression is fully controllable. PMID:21528072

Influence of interplanetary solar wind sector polarity on the ionosphere

NASA Astrophysics Data System (ADS)

liu, jing

2014-05-01

Knowledge of solar sector polarity effects on the ionosphere may provide some clues in understanding of the ionospheric day-to-day variability. A solar-terrestrial connection ranging from solar sector boundary (SB) crossings, geomagnetic disturbance and ionospheric perturbations has been demonstrated. The increases in interplanetary solar wind speed within three days are seen after SB crossings, while the decreases in solar wind dynamic pressure and magnetic field intensity immediately after SB crossings are confirmed by the superposed epoch analysis results. Furthermore, the interplanetary magnetic field (IMF) Bz component turns from northward to southward in March equinox and June solstice as the Earth passes from a solar sector of outward to inward directed magnetic fields, whereas the reverse situation occurs for the transition from toward to away sectors. The F2 region critical frequency (foF2) covering about four solar cycles and total electron content (TEC) during 1998-2011 are utilized to extract the related information, revealing that they are not modified significantly and vary within the range of 15% on average. The responses of the ionospheric TEC to SB crossings exhibit complex temporal and spatial variations and have strong dependencies on season, latitude, and solar cycle. This effect is more appreciable in equinoctial months than in solstitial months, which is mainly caused by larger southward Bz components in equinox. In September equinox, latitudinal profile of relative variations of foF2 at noon is featured by depressions at high latitudes and enhancements in low-equatorial latitudes during IMF away sectors. The negative phase of foF2 is delayed at solar minimum relative to it during other parts of solar cycle, which might be associated with the difference in longevity of major interplanetary solar wind drivers perturbing the Earth's environment in different phases of solar cycle.

Properties of the suprathermal heavy ion population near 1 AU during solar cycles 23 and 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dayeh, Maher A., E-mail: maldayeh@swri.edu; Ebert, Robert W.; Desai, Mihir I.

2016-03-25

Using measurements from the Advanced Composition Explorer/Ultra-Low Energy Isotope Spectrometer (ACE/ULEIS) near 1 AU, we surveyed the composition and spectra of heavy ions (He-through-Fe) during interplanetary quiet times from 1998 January 1 to 2014 December 31 at suprathermal energies between ∼0.11 and ∼1.28 MeV nucleon{sup −1}. The selected time period covers the maxima of solar cycles 23 and 24 and the extended solar minimum in between. We find the following: (1) The number of quiet-hours in each year correlates well with the sunspot number, year 2009 was the quietest for about 90% of the time; (2) The composition of the quiet-timemore » suprathermal heavy ion population ({sup 3}He, C-through-O, and Fe) correlates well with the level of solar activity, exhibiting SEP-like composition signatures during solar maximum, and CIR- or solar wind-like composition during solar minimum; (3) The heavy ion spectra at ∼0.11-0.32 MeV nucleon{sup −1} exhibit suprathermal tails with power-law spectral indices ranging from 1.4 to 2.7. (4) Fe spectral indices get softer (steeper) from solar minimum of cycle 23 to solar cycle 24 maximum. These results imply that during IP quiet times and at energies above ∼0.1 MeV nucleon{sup −1}, the IP medium is dominated by material from prior solar and interplanetary events.« less

Critical frequencies of the ionospheric F1 and F2 layers during the last four solar cycles: Sunspot group type dependencies

NASA Astrophysics Data System (ADS)

Yiǧit, Erdal; Kilcik, Ali; Elias, Ana Georgina; Dönmez, Burçin; Ozguc, Atila; Yurchshyn, Vasyl; Rozelot, Jean-Pierre

2018-06-01

The long term solar activity dependencies of ionospheric F1 and F2 regions' critical frequencies (f0F1 and f0F2) are analyzed for the last four solar cycles (1976-2015). We show that the ionospheric F1 and F2 regions have different solar activity dependencies in terms of the sunspot group (SG) numbers: F1 region critical frequency (f0F1) peaks at the same time with the small SG numbers, while the f0F2 reaches its maximum at the same time with the large SG numbers, especially during the solar cycle 23. The observed differences in the sensitivity of ionospheric critical frequencies to sunspot group (SG) numbers provide a new insight into the solar activity effects on the ionosphere and space weather. While the F1 layer is influenced by the slow solar wind, which is largely associated with small SGs, the ionospheric F2 layer is more sensitive to Coronal Mass Ejections (CMEs) and fast solar winds, which are mainly produced by large SGs and coronal holes. The SG numbers maximize during of peak of the solar cycle and the number of coronal holes peaks during the sunspot declining phase. During solar minimum there are relatively less large SGs, hence reduced CME and flare activity. These results provide a new perspective for assessing how the different regions of the ionosphere respond to space weather effects.

Can solar cycle modulate the ENSO effect on the Pacific/North American pattern?

NASA Astrophysics Data System (ADS)

Li, Delin; Xiao, Ziniu

2018-01-01

The ENSO effect on the Pacific/North American pattern (PNA) is well-known robust. Recent studies from observations and model simulations have reported that some important atmospheric circulation systems of extratropics are markedly modulated by the 11-year solar cycle. But less effort has been devoted to revealing the solar influence on the PNA. We thus hypothesize that the instability and uncertainty in the relationship between solar activity and PNA could be due to the ENSO impacts. In this study, solar cycle modulation of the ENSO effect on the PNA has been statistically examined by the observations from NOAA and NCEP/NCAR for the period of 1950-2014. Results indicate that during the high solar activity (HS) years, the PNA has stronger relevance to the ENSO, and the response of tropospheric geopotential height to ENSO variability is broadly similar to the typical positive PNA pattern. However, in the case of low solar activity (LS) years, the correlation between ENSO and PNA decreases relatively and the response has some resemblance to the negative phase of Arctic Oscillation (AO). Also, we find the impacts of solar activity on the middle troposphere are asymmetric during the different solar cycle phases, and the weak PNA-like response to solar activity only presents in the HS years. Closer inspection suggests that the higher solar activity has a much more remarkable modulation on the PNA-like response to the warm ENSO (WE) than that to the cold ENSO (CE), particularly over the Northeast Pacific region. The possible cause of the different responses might be the solar influence on the subtropical westerlies of upper troposphere. When the sea surface temperature (SST) of east-central tropical Pacific is anomalously warm, the upper tropospheric westerlies are significantly modulated by the higher solar activity, resulting in the acceleration and eastward shift of the North Pacific subtropical jet, which favors the propagation of WE signal from the tropical Pacific to the North Pacific, and consequently leading to the development of positive PNA-like pattern during the WE phase. Thus, it seems that the solar cycle can significantly modulate the WE effect on the PNA under the HS background.

Cold plasma selectivity in the interaction with various types of the cells

NASA Astrophysics Data System (ADS)

Volotskova, Olga; Stepp, Mary Ann; Keidar, Michael

2011-10-01

Present research in the area of cold atmospheric plasma (CAP) demonstrates great potential in various areas including medicine and biology. Depending on their configuration they can be used for wound healing, sterilization, targeted cell/tissue removal, and cancer treatments. Here we explore potential mechanisms by which CAP alters cell migration and influences cell adhesion. The migration studies are focused on the CAP interaction with fibroblasts and corneal epithelial cells. Data show that various types of cells have different thresholds (treatment times) required to achieve maximum inhibition of cell migration which is around ~30-40%. Studies to assess the impact of CAP treatment on the activation state of integrins and focal adhesion size by immunofluorescence showed more active b1 integrin on the cell surface and large focal adhesions after CAP treatment. Based on these data, a thermodynamic model is presented to explain how CAP leads to integrin activation and focal adhesion assembly. Also responses of the various types of the cells to the cold plasma treatment on the example of the epithelial keratinocytes, papilloma and carcinoma cells are studied. Cell cycle, migration and cell vitality analysis were performed. The goal of this study is to understand the mechanism by which the CAP jet alters cell migration, influences adhesion and cell survival.

Characteristics of high-purity Teflon vial for 14C measurement in old tree rings

NASA Astrophysics Data System (ADS)

Sakurai, H.; Saswaki, Y.; Matsumoto, T.; Aoki, T.; Kato, W.; Gandou, T.; Gunji, S.; Tokanai, F.

2003-06-01

14C concentration in single-year tree rings of an old cedar of ca. 2500 years ago is measured to investigate the 11-yr periodicity of solar activity. Our highly accurate 14C measuring system is composed of a benzene synthesizer capable of producing a large quantity (10 g) of benzene and a Quantulus 1220™ liquid scintillation counting system. The accuracy is less than 0.2% for measurements of 14C concentration. The benzene sample is contained in a high-purity Teflon/copper-counting vial (20 ml) manufactured by Wallac Oy Company. We found a vial with an irregular copper cap for the measurements of 11 tree rings. The behavior of the vial with the irregular cap was investigated. The Teflon sheet inside the cap plays an important role in achieving stable measurement. The rate of volatilization of the benzene was less than 0.35 mg/day for vials with ordinary caps. This results in the volatilization rate of 0.003% for 10.5 g of benzene and hence guarantees measurement at an accuracy of 0.2% for 70 days.

Heartbeat of the Sun from Principal Component Analysis and prediction of solar activity on a millenium timescale

PubMed Central

Zharkova, V. V.; Shepherd, S. J.; Popova, E.; Zharkov, S. I.

2015-01-01

We derive two principal components (PCs) of temporal magnetic field variations over the solar cycles 21–24 from full disk magnetograms covering about 39% of data variance, with σ = 0.67. These PCs are attributed to two main magnetic waves travelling from the opposite hemispheres with close frequencies and increasing phase shift. Using symbolic regeression analysis we also derive mathematical formulae for these waves and calculate their summary curve which we show is linked to solar activity index. Extrapolation of the PCs backward for 800 years reveals the two 350-year grand cycles superimposed on 22 year-cycles with the features showing a remarkable resemblance to sunspot activity reported in the past including the Maunder and Dalton minimum. The summary curve calculated for the next millennium predicts further three grand cycles with the closest grand minimum occurring in the forthcoming cycles 26–27 with the two magnetic field waves separating into the opposite hemispheres leading to strongly reduced solar activity. These grand cycle variations are probed by α − Ω dynamo model with meridional circulation. Dynamo waves are found generated with close frequencies whose interaction leads to beating effects responsible for the grand cycles (350–400 years) superimposed on a standard 22 year cycle. This approach opens a new era in investigation and confident prediction of solar activity on a millenium timescale. PMID:26511513

Solar High Temperature Water-Splitting Cycle with Quantum Boost

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Robin; Davenport, Roger; Talbot, Jan

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 formore » 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 proposed for future activities. Electrolysis membranes that permit higher temperatures and lower voltages are attainable. The oxygen half cycle will need further development and improvement.« less

The Peculiar Solar Minimum 23/24 Revealed by the Microwave Butterfly Diagram

NASA Technical Reports Server (NTRS)

Gopalswamy, Natchimuthuk; Yashiro, Seiji; Makela, Pertti; Shibasaki, Kiyoto; Hathaway, David

2010-01-01

The diminished polar magnetic field strength during the minimum between cycles 23 and 24 is also reflected in the thermal radio emission originating from the polar chromosphere. During solar minima, the polar corona has extended coronal holes containing intense unipolar flux. In microwave images, the coronal holes appear bright, with a brightness enhancement of 500 to 2000 K with respect to the quiet Sun. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is approx.10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes..

Planetary resonances, bi-stable oscillation modes, and solar activity cycles

NASA Technical Reports Server (NTRS)

Sleeper, H. P., Jr.

1972-01-01

The natural resonance structure of the planets in the solar system yields resonance periods of 11.08 and 180 years. The 11.08 year period is due to resonance of the sidereal periods of the three inner planets. The 180-year period is due to synodic resonances of the four major planets. These periods are also observed in the sunspot time series. The 11-year sunspot cycles from 1 to 19 are separated into categories of positive and negative cycles, Mode 1 and Mode 2 cycles, and typical and anomalous cycles. Each category has a characteristic shape, magnitude, or duration, so that statistical prediction techniques are improved when a cycle can be classified in a given category. These categories provide evidence for bistable modes of solar oscillation. The next minimum is expected in 1977 and the next maximum in 1981 or later. These epoch values are 2.5 years later than those based on typical cycle characteristics.

An investigation of the solar cycle response of odd-nitrogen in the thermosphere

NASA Technical Reports Server (NTRS)

Rusch, David W.; Solomon, Stanley C.

1992-01-01

This annual report covers the first year of funding for the study of the solar cycle variations of odd-nitrogen (N((sup 2)D), N((sup 4)S), NO) in the Earth's thermosphere. The study uses the extensive data base generated by the Atmosphere Explorer (AE) satellites, and the Solar Mesosphere Explorer Satellite. The AE data are being used, for the first time, to define the solar variability effect on the odd-nitrogen species through analysis of the emissions at 520 nano-m from N((sup 2)D) and the emission from O(+)((sup 2)P). Additional AE neutral and ion density data are used to help define and quantify the physical processes controlling the variations. The results from the airglow study will be used in the next two years of this study to explain the solar cycle changes in NO measured by the Solar Mesosphere Explorer.

Model of Energy Spectrum Parameters of Ground Level Enhancement Events in Solar Cycle 23

NASA Astrophysics Data System (ADS)

Wu, S.-S.; Qin, G.

2018-01-01

Mewaldt et al. (2012) fitted the observations of the ground level enhancement (GLE) events during solar cycle 23 to the double power law equation to obtain the four spectral parameters, the normalization constant C, low-energy power law slope γ1, high-energy power law slope γ2, and break energy E0. There are 16 GLEs from which we select 13 for study by excluding some events with complicated situation. We analyze the four parameters with conditions of the corresponding solar events. According to solar event conditions, we divide the GLEs into two groups, one with strong acceleration by interplanetary shocks and another one without strong acceleration. By fitting the four parameters with solar event conditions we obtain models of the parameters for the two groups of GLEs separately. Therefore, we establish a model of energy spectrum of solar cycle 23 GLEs, which may be used in prediction in the future.

Effect of solar proton events on the middle atmosphere during the past two solar cycles as computed using a two-dimensional model

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Douglass, Anne R.; Rood, Richard B.; Mcpeters, Richard D.; Meade, Paul E.

1990-01-01

This paper investigates the effects of solar proton events (SPEs) on the middle atmosphere during the past two solar cycles (1963-1984), by examining changes in the production of odd nitrogen, NO(y), and ozone and using a proton energy degradation scheme to derive ion pair production rates. These calculations show that NO(y) is not substantially changed over a solar cycle by SPEs; significant SPEs last only 1-5 days, tend to occur near solar maximum, and are typically months to years apart, preventing a build up of SPE-produced NO(y). Fractional ozone changes are even smaller than the fractional NO(y) changes and are significant only for the August 1972 SPE. Ozone, like NO(y), returns to its ambient levels on time scales of several months to a year.

Evolution of 3D electron density of the solar corona from the minimum to maximum of Solar Cycle 24

NASA Astrophysics Data System (ADS)

Wang, Tongjiang; Reginald, Nelson L.; Davila, Joseph M.; St Cyr, O. C.

2016-10-01

The variability of the solar white-light corona and its connection to the solar activity has been studied for more than a half century. It is widely accepted that the temporal variation of the total radiance of the K-corona follows the solar cycle pattern (e.g., correlated with sunspot number). However, the origin of this variation and its relationships with regard to coronal mass ejections and the solar wind are yet to be clearly understood. COR1-A and -B instruments onboard the STEREO spacecraft have continued to perform high-cadence (5 min) polarized brightness (pB) measurements from two different vantage points from the solar minimum to the solar maximum of Solar Cycle 24. With these pB observations we have reconstructed the 3D coronal density between 1.5-4.0 solar radii for 100 Carrington rotations (CRs) from 2007 to 2014 using the spherically symmetric inversion (SSI) method. We validate these 3D density reconstructions by other means such as tomography, MHD modeling, and pB inversion of LASCO/C2 data. We analyze the solar cycle variations of total coronal mass (or average density) over the global Sun and in two hemispheres, as well as the variations of the streamer area and mean density. We find the short-term oscillations of 8-9 CRs during the ascending and maximum phases through wavelet analysis. We explore the origin of these oscillations based on evolution of the photospheric magnetic flux and coronal structures.

A New SATIRE-S Spectral Solar Irradiance Reconstruction for Solar Cycles 21-23 and Its Implications for Stratospheric Ozone*

NASA Astrophysics Data System (ADS)

Ball, William T.; Krivova, Natalie A.; Unruh, Yvonne C.; Haigh, Joanna D.; Solanki, Sami K.

2014-11-01

We present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the SATIRE-S model. The SSI reconstruction covers wavelengths between 115 and 160,000 nm and all dates between August 1974 and October 2009. This represents the first full-wavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the NRLSSI model and SORCE/SOLSTICE ultraviolet (UV) observations. SATIRE-S displays similar cycle behaviour to NRLSSI for wavelengths below 242 nm and almost twice the variability between 242 and 310 nm. During the decline of last solar cycle, between 2003 and 2008, SSI from SORCE/SOLSTICE version 12 and 10 typically displays more than three times the variability of SATIRE-S between 200 and 300 nm. All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modelled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE/SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE/SOLSTICE irradiances. The recalibrated SORCE/SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than when using version 10 and now similar in magnitude to SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient to warrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.

Seasonal Variation of High-latitude Geomagnetic Activity Revisited

NASA Astrophysics Data System (ADS)

Tanskanen, E.; Hynönen, R.; Mursula, K.

2017-12-01

The coupling of the solar wind and auroral region has been examined by using westward electrojet indices since 1966 - 2014. We have studied the seasonal variation of high-latitude geomagnetic activity in individual years for solar cycles 20 - 24. The classical two-equinox activity pattern in geomagnetic activity was seen in multi-year averages but it was found in less than one third of the years examined. We found that the seasonal variation of high-latitude geomagnetic activity closely follows the solar wind speed. While the mechanisms leading to the two-equinox maxima pattern are in operation, the long-term change of solar wind speed tends to mask the effect of these mechanisms for individual years. We identified the most active and the second most active season based on westward electrojet indices AL (1966 - 2014) and IL (1995 - 2014). The annual maximum is found at either equinox in 2/3 and at either solstice in 1/3 of the years examined. Large cycle-to-cycle variation is found in the seasonal pattern: equinox maxima are more common during cycles 21 and 22 than in cycles 23 or 24. An exceptionally long winter dominance in high-latitude activity and solar wind speed is seen in the declining phase of cycle 23, after the appearance of the long-lasting low-latitude coronal hole.

Solar Surface Velocity in the Large Scale estimated by Magnetic Element Tracking Method

NASA Astrophysics Data System (ADS)

Fujiyama, M.; Imada, S.; Iijima, H.; Machida, S.

2017-12-01

The 11years variation in the solar activity is one of the important sources of decadal variation in the solar-terrestrial environment. Therefore, predicting the solar cycle activity is crucial for the space weather. To build the 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 cycle activity is intensively discussed. Nowadays, many people believe that the polar magnetic field at the solar minimum is one of the best predictor for the next solar cycle. To estimate polar magnetic field, Surface Flux Transport (SFT) model have been often used. On the other hand, SFT model needs several parameters, for example Meridional circulation, differential rotation, turbulent diffusion etc.. So far, those parameters have not been fully understood, and their uncertainties may affect the accuracy of the prediction. In this study, we try to discuss the parameters which are used in SFT model. We focus on two kinds of the solar surface motions, Differential rotation and Meridional circulation. First, we have developed Magnetic Element Tracking (MET) module, which is able to obtain the surface velocity by using the magnetic field data. We have used SOHO/MDI and SDO/HMI for the magnetic field data. By using MET, we study the solar surface motion over 2 cycle (nearly 24 years), and we found that the velocity variation is related to the active region belt. This result is consistent with [Hathaway et al., 2011]. Further, we apply our module to the Hinode/SOT data which spatial resolution is high. Because of its high resolution, we can discuss the surface motion close to the pole which has not been discussed enough. Further, we discuss the relationship between the surface motion and the magnetic field strength and the location of longitude.

Influence of the Solar Cycle on Turbulence Properties and Cosmic-Ray Diffusion

NASA Astrophysics Data System (ADS)

Zhao, L.-L.; Adhikari, L.; Zank, G. P.; Hu, Q.; Feng, X. S.

2018-04-01

The solar cycle dependence of various turbulence quantities and cosmic-ray (CR) diffusion coefficients is investigated by using OMNI 1 minute resolution data over 22 years. We employ Elsässer variables z ± to calculate the magnetic field turbulence energy and correlation lengths for both the inwardly and outwardly directed interplanetary magnetic field (IMF). We present the temporal evolution of both large-scale solar wind (SW) plasma variables and small-scale magnetic fluctuations. Based on these observed quantities, we study the influence of solar activity on CR parallel and perpendicular diffusion using quasi-linear theory and nonlinear guiding center theory, respectively. We also evaluate the radial evolution of the CR diffusion coefficients by using the boundary conditions for different solar activity levels. We find that in the ecliptic plane at 1 au (1), the large-scale SW temperature T, velocity V sw, Alfvén speed V A , and IMF magnitude B 0 are positively related to solar activity; (2) the fluctuating magnetic energy density < {{z}+/- }2> , residual energy E D , and corresponding correlation functions all have an obvious solar cycle dependence. The residual energy E D is always negative, which indicates that the energy in magnetic fluctuations is larger than the energy in kinetic fluctuations, especially at solar maximum; (3) the correlation length λ for magnetic fluctuations does not show significant solar cycle variation; (4) the temporally varying shear source of turbulence, which is most important in the inner heliosphere, depends on the solar cycle; (5) small-scale fluctuations may not depend on the direction of the background magnetic field; and (6) high levels of SW fluctuations will increase CR perpendicular diffusion and decrease CR parallel diffusion, but this trend can be masked if the background IMF changes in concert with turbulence in response to solar activity. These results provide quantitative inputs for both turbulence transport models and CR diffusion models, and also provide valuable insight into the long-term modulation of CRs in the heliosphere.

Solar cycle dependence of the heliospheric shape deduced from a global MHD simulation of the interaction process between a nonuniform time-dependent solar wind and the local interstellar medium

NASA Astrophysics Data System (ADS)

Tanaka, T.; Washimi, H.

1999-06-01

The global structure of the solar wind/very local interstellar medium interaction is studied from a fully three-dimensional time-dependent magnetohydrodynamic model, in which the solar wind speed increases from 400 to 800 km/s in going from the ecliptic to pole and the heliolatitude of the low-high-speed boundary changes from 30° to 80° in going from the solar minimum to solar maximum. In addition, the interplanetary magnetic field (IMF) changes its polarity at the solar maximum. As a whole, the shapes of the terminal shock (TS) and heliopause (HP) are elongated along the solar polar axis owing to a high solar wind ram pressure over the poles. In the ecliptic plane, the heliospheric structure changes little throughout a solar cycle. The TS in this plane shows a characteristic bullet-shaped structure. In the polar plane, on the other hand, the shape of the TS exhibits many specific structures according to the stage of the solar cycle. These structures include the polygonal configuration of the polar TS seen around the solar minimum, the mesa- and terrace-shaped TSs in the high- and low-speed solar wind regions seen around the ascending phase, and the chimney-shaped TS in the high-speed solar wind region seen around the solar maximum. These structures are formed from different combinations of right-angle shock, oblique shock, and steep oblique shock so as to transport the heliosheath plasma most efficiently toward the heliotail (HT). In the HT, the hot and weakly-magnetized plasma from the high-heliolatitude TS invades as far as the ecliptic plane. A weakly time-dependent recirculation flow in the HT is a manifestation of invading flow. Distributions of magnetic field in the HT, which are a pile-up of the compressed MF over several solar cycles, are modified by the flow from high-heliolatitude.

Impacts of Wind and Solar on Fossil-Fueled Generators: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lew, D.; Brinkman, G.; Kumar, N.

2012-08-01

High penetrations of wind and solar power will impact the operations of the remaining generators on the power system. Regional integration studies have shown that wind and solar may cause fossil-fueled generators to cycle on and off and ramp down to part load more frequently and potentially more rapidly. Increased cycling, deeper load following, and rapid ramping may result in wear-and-tear impacts on fossil-fueled generators that lead to increased capital and maintenance costs, increased equivalent forced outage rates, and degraded performance over time. Heat rates and emissions from fossil-fueled generators may be higher during cycling and ramping than during steady-statemore » operation. Many wind and solar integration studies have not taken these increased cost and emissions impacts into account because data have not been available. This analysis considers the cost and emissions impacts of cycling and ramping of fossil-fueled generation to refine assessments of wind and solar impacts on the power system.« less

Dynamo generation of magnetic fields in three-dimensional space - Solar cycle main flux tube formation and reversals

NASA Astrophysics Data System (ADS)

Yoshimura, H.

1983-08-01

The case of the solar magnetic cycle is investigated as a prototype of the dynamo processes involved in the generation of magnetic fields in astrophysics. Magnetohydrodynamic (MHD) equations are solved using a numerical method with a prescribed velocity field in order follow the movement and deformation. It is shown that a simple combination of differential rotation and global convection, given by a linear analysis of fluid dynamics in a rotating sphere, can perpetually create and reverse great magnetic flux tubes encircling the sun. These main flux tubes of the solar cycle are the progenitors of small-scale flux ropes of the solar activity. These findings indicate that magnetic fields can be generated by fluid motions and that MHD equations have a new type of oscillatory solution. It is shown that the solar cycle can be identified with one of these oscillatory solutions. It is proposed that the formation of magnetic flux tubes by streaming plasma flows is a universal mechanism of flux tube formation in astrophysics.

The sun's magnetic sector structure

NASA Technical Reports Server (NTRS)

Svalgaard, L.; Wilcox, J. M.; Scherrer, P. H.; Howard, R.

1975-01-01

The synoptic appearance of solar magnetic sectors is studied using 454 sector boundaries observed at earth during 1959-1973. The sectors are clearly visible in the photospheric magnetic field. Sector boundaries can be clearly identified as north-south running demarcation lines between regions of persistent magnetic polarity imbalances. These regions extend up to about 35 deg of latitude on both sides of the equator. They generally do not extend into the polar caps. The polar cap boundary can be identified as an east-west demarcation line marking the poleward limit of the sectors. The typical flux imbalance for a magnetic sector is about 4 x 10 to the 21st power Maxwells.

Effects of plasma drag on low Earth orbiting satellites due to solar forcing induced perturbations and heating

NASA Astrophysics Data System (ADS)

Nwankwo, Victor U. J.; Chakrabarti, Sandip K.; Weigel, Robert S.

2015-07-01

The upper atmosphere changes significantly in temperature, density and composition as a result of solar cycle variations, which causes severe storms and flares, and increases in the amount of absorbed solar radiation from solar energetic events. Satellite orbits are consequently affected by this process, especially those in low Earth orbit (LEO). In this paper, we present a model of atmospheric drag effects on the trajectory of two hypothetical LEO satellites of different ballistic coefficients, initially injected at h = 450 km. We investigate long-term trends of atmospheric drag on LEO satellites due to solar forcing induced atmospheric perturbations and heating at different phases of the solar cycle, and during short intervals of strong geomagnetic disturbances or magnetic storms. We show dependence of orbital decay on the severity of both solar cycle and phase and the extent of geomagnetic perturbations. The result of the model compares well with observed decay profile of some existing LEO satellites and provide a justification of the theoretical considerations used here.

Solar signals detected within neutral atmospheric and ionospheric parameters

NASA Astrophysics Data System (ADS)

Koucka Knizova, Petra; Georgieva, Katya; Mosna, Zbysek; Kozubek, Michal; Kouba, Daniel; Kirov, Boian; Potuzníkova, Katerina; Boska, Josef

2018-06-01

We have analyzed time series of solar data together with the atmospheric and ionospheric measurements for solar cycles 19 till 23 according to particular data availability. For the analyses we have used long term data with 1-day sampling. By mean of Continuous Wavelet Transform (CWT) we have found common spectral domains within solar and atmospheric and ionospheric time series. Further we have identified terms when particular pairs of signals show high coherence applying Wavelet Transform Coherence (WTC). Despite wide oscillation ranges detected in particular time series CWT spectra we found only limited domains with high coherence by mean of WTC. Wavelet Transform Coherence reveals significant high power domains with stable phase difference for periods 1 month, 2 months, 6 months, 1 year, 2 years and 3-4 years between pairs of solar data and atmospheric and ionospheric data. The occurence of the detected domains vary significantly during particular solar cycle (SC) and from cycle to the following one. It indicates the changing solar forcing and/or atmospheric sensitivity with time.

What the Sunspot Record Tells Us About Space Climate

NASA Technical Reports Server (NTRS)

Hathaway, David H.; Wilson, Robert M.

2004-01-01

The records concerning the number, sizes, and positions of sunspots provide a direct means of characterizing solar activity over nearly 400 years. Sunspot numbers are strongly correlated with modem measures of solar activity including: 10.7-cm radio flux, total irradiance, x-ray flares, sunspot area, the baseline level of geomagnetic activity, and the flux of galactic cosmic rays. The Group Sunspot Number provides information on 27 sunspot cycles, far more than any of the modem measures of solar activity, and enough to provide important details about long-term variations in solar activity or Space Climate. The sunspot record shows: 1) sunspot cycles have periods of 131 plus or minus 14 months with a normal distribution; 2) sunspot cycles are asymmetric with a fast rise and slow decline; 3) the rise time from minimum to maximum decreases with cycle amplitude; 4) large amplitude cycles are preceded by short period cycles; 5 ) large amplitude cycles are preceded by high minima; 6) although the two hemispheres remain linked in phase, there are significant asymmetries in the activity in each hemisphere; 7) the rate at which the active latitudes drift toward the equator is anti-correlated with the cycle period, 8) the rate at which the active latitudes drift toward the equator is positively correlated with the amplitude of the cycle after the next; 9) there has been a significant secular increase in the amplitudes of the sunspot cycles since the end of the Maunder Minimum (1715); and 10) there is weak evidence for a quasi-periodic variation in the sunspot cycle amplitudes with a period of about 90 years. These characteristics indicate that the next solar cycle should have a maximum smoothed sunspot number of about 1.45 plus or minus 30 in 2010 while the following cycle should have a maximum of about 70 plus or minus 30 in 2023.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael, A. T.; Opher, M.; Provornikova, E.

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 fieldmore » 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.« less

Changes in the relationship NAO-Northern Hemisphere Temperature due to solar activity

NASA Astrophysics Data System (ADS)

de La Torre, L.; Gimeno, L.; Añel, J. A.; Nieto, R.; Tesouro, M.; Ribera, P.; García, R.; Hernández, E.

2003-04-01

The influence of the North Atlantic Oscillation (NAO) on wintertime Northern Hemisphere Temperature (NHT) is investigated. To check the hypothesis that the solar cycle is modulating this relationship, the sample was divided into two groups, one included the years corresponding to the three consecutive lowest values of sunspots number for every 11-years cycle (43 years) and the other the ones corresponding to the three consecutive highest numbers (39 years) for every 11-years cycle. If the data of each year were independent, the correlation coefficients between NAO index and NHT for 43 (39) years would be 0.30 (0.32) at 95% confidence level. Correlation index corresponding to the solar minimum phases was -0.17 and to the solar maximum phases was 0.35. The second result is statistically significant and indicates that there are periods when a positive phase of the NAO is related to positive anomalies of NHT- result that supports our current idea of the influence of the NAO on temperature- but there are other periods when NAO and NHT are not correlated. So, results suggest that this relationship has different sign according to the phase of the solar cycle. For solar maximum phases NAO and NHT are positively correlated -result assumed up to the moment- but for solar minimum phases correlations are not significant or even negative. This result is in agreement with the different extension of the NAO for solar cycle phases [1] - almost hemispheric for maximum phases and confined to the eastern Atlantic for minimum phases-.

Cyclic Alternating Pattern in Obstructive Sleep Apnea Patients with versus without Excessive Sleepiness.

PubMed

Korkmaz, Selda; Bilecenoglu, Nedime Tugce; Aksu, Murat; Yoldas, Tahir Kurtulus

2018-01-01

One of the main hypotheses on the development of daytime sleepiness (ES) is increased arousal in obstructive sleep apnea (OSA). Cyclic alternating pattern (CAP) is considered to be the main expression of sleep microstructure rather than arousal. Therefore, we aimed to investigate whether there is any difference between OSA patients with versus without ES in terms of the parameters of sleep macro- and microstructure and which variables are associated with Epworth Sleepiness Scale (ESS) score. Thirty-eight male patients with moderate to severe OSA were divided into two subgroups by having been used to ESS as ES or non-ES. There was no difference between two groups in clinical characteristics and macrostructure parameters of sleep. However, ES group had significantly higher CAP rate, CAP duration, number of CAP cycles, and duration and rate of the subtypes A2 ( p = 0.033, 0.019, 0.013, and 0.019, respectively) and lower mean phase B duration ( p = 0.028) compared with non-ES group. In correlation analysis, ESS score was not correlated with any CAP measure. OSA patients with ES have increased CAP measures rather than those without ES.

Variations in the temperature and circulation of the atmosphere during the 11-year cycle of solar activity derived from the ERA-Interim reanalysis data

NASA Astrophysics Data System (ADS)

Gruzdev, A. N.

2017-07-01

Using the data of the ERA-Interim reanalysis, we have obtained estimates of changes in temperature, the geopotential and its large-scale zonal harmonics, wind velocity, and potential vorticity in the troposphere and stratosphere of the Northern and Southern hemispheres during the 11-year solar cycle. The estimates have been obtained using the method of multiple linear regression. Specific features of response of the indicated atmospheric parameters to the solar cycle have been revealed in particular regions of the atmosphere for a whole year and depending on the season. The results of the analysis indicate the existence of a reliable statistical relationship of large-scale dynamic and thermodynamic processes in the troposphere and stratosphere with the 11-year solar cycle.

An Empirical Orthogonal Function Reanalysis of the Northern Polar External and Induced Magnetic Field During Solar Cycle 23

NASA Astrophysics Data System (ADS)

Shore, R. M.; Freeman, M. P.; Gjerloev, J. W.

2018-01-01

We apply the method of data-interpolating empirical orthogonal functions (EOFs) to ground-based magnetic vector data from the SuperMAG archive to produce a series of month length reanalyses of the surface external and induced magnetic field (SEIMF) in 110,000 km2 equal-area bins over the entire northern polar region at 5 min cadence over solar cycle 23, from 1997.0 to 2009.0. Each EOF reanalysis also decomposes the measured SEIMF variation into a hierarchy of spatiotemporal patterns which are ordered by their contribution to the monthly magnetic field variance. We find that the leading EOF patterns can each be (subjectively) interpreted as well-known SEIMF systems or their equivalent current systems. The relationship of the equivalent currents to the true current flow is not investigated. We track the leading SEIMF or equivalent current systems of similar type by intermonthly spatial correlation and apply graph theory to (objectively) group their appearance and relative importance throughout a solar cycle, revealing seasonal and solar cycle variation. In this way, we identify the spatiotemporal patterns that maximally contribute to SEIMF variability over a solar cycle. We propose this combination of EOF and graph theory as a powerful method for objectively defining and investigating the structure and variability of the SEIMF or their equivalent ionospheric currents for use in both geomagnetism and space weather applications. It is demonstrated here on solar cycle 23 but is extendable to any epoch with sufficient data coverage.

Long-term Trends in Interplanetary Magnetic Field Strength and Solar Wind Structure during the 20th Century

NASA Technical Reports Server (NTRS)

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

2002-01-01

Lockwood et al have recently reported an approximately 40% increase in the radial component of the interplanetary magnetic field (IMF) at Earth between 1964 and 1996. We argue that this increase does not constitute a secular trend but is largely the consequence of lower than average fields during solar cycle 20 (1964-1976) in comparison with surrounding cycles. For times after 1976 the average IMF strength has actually decreased slightly. Examination of the cosmic ray intensity, an indirect measure of the IMF strength, over the last five solar cycles (19-23) also indicates that cycle averages of the IMF strength have been relatively constant since approximately 1954. We also consider the origin of the well-documented increase in the geomagnetic alphaalpha index that occurred primarily during the first half of the twentieth century. We surmise that the coronal mass ejection (CME) rate for recent solar cycles was approximately twice as high as that for solar cycles 100 years ago. However, this change in the CME rate and the accompanying increase in 27-day recurrent storm activity reported by others are unable to account completely for the increase in alphaalpha. Rather, the CMEs and recurrent high-speed streams at the beginning of the twentieth century must have been embedded in a background of slow solar wind that was less geoeffective (having, for example, lower IMF strength and/or flow speed) than its modern counterpart.

MGS TES observations of the water vapor above the seasonal and perennial ice caps during northern spring and summer

NASA Astrophysics Data System (ADS)

Pankine, Alexey A.; Tamppari, Leslie K.; Smith, Michael D.

2010-11-01

We report on new retrievals of water vapor column abundances from the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) data. The new retrievals are from the TES nadir data taken above the 'cold' surface areas in the North polar region ( Tsurf < 220 K, including seasonal frost and permanent ice cap) during spring and summer seasons, where retrievals were not performed initially. Retrievals are possible (with some modifications to the original algorithm) over cold surfaces overlaid by sufficiently warm atmosphere. The retrieved water vapor column abundances are compared to the column abundances observed by other spacecrafts in the Northern polar region during spring and summer and good agreement is found. We detect an annulus of water vapor growing above the edge of the retreating seasonal cap during spring. The formation of the vapor annulus is consistent with the previously proposed mechanism for water cycling in the polar region, according to which vapor released by frost sublimation during spring re-condenses on the retreating seasonal CO 2 cap. The source of the vapor in the vapor annulus, according to this model, is the water frost on the surface of the CO 2 at the retreating edge of the cap and the frost on the ground that is exposed by the retreating cap. Small contribution from regolith sources is possible too, but cannot be quantified based on the TES vapor data alone. Water vapor annulus exhibits interannual variability, which we attribute to variations in the atmospheric temperature. We propose that during spring and summer the water ice sublimation is retarded by high relative humidity of the local atmosphere, and that higher atmospheric temperatures lead to higher vapor column abundances by increasing the water holding capacity of the atmosphere. Since the atmospheric temperatures are strongly influenced by the atmospheric dust content, local dust storms may be controlling the release of vapor into the polar atmosphere. Water vapor abundances above the residual polar cap also exhibit noticeable interannual variability. In some years abundances above the cap are lower than the abundances outside of the cap, consistent with previous observations, while in the other years the abundances above the cap are higher or similar to abundances outside of the cap. We speculate that the differences may be due to weaker off-cap transport in the latter case, keeping more vapor closer to the source at the surface of the residual cap. Despite the large observed variability in water vapor column abundances in the Northern polar region during spring and summer, the latitudinal distribution of the vapor mass in the atmosphere is very similar during the summer season. If the variability in vapor abundances is caused by the variability of vapor sources across the residual cap then this would mean that they annually contribute relatively little vapor mass to significantly affect the vapor mass budget. Alternatively this may suggest that the vapor variability is caused by the variability of the polar atmospheric circulation. The new water vapor retrievals should be useful in tuning the Global Circulation Models of the martian water cycle.

Seasonal Variation of High-Latitude Geomagnetic Activity in Individual Years

NASA Astrophysics Data System (ADS)

Tanskanen, E. I.; Hynönen, R.; Mursula, K.

2017-10-01

We study the seasonal variation of high-latitude geomagnetic activity in individual years in 1966-2014 (solar cycles 20-24) by identifying the most active and the second most active season based on westward electrojet indices AL (1966-2014) and IL (1995-2014). The annual maximum is found at either equinox in two thirds and at either solstice in one third of the years examined. The traditional two-equinox maximum pattern is found in roughly one fourth of the years. We found that the seasonal variation of high-latitude geomagnetic activity closely follows the solar wind speed. While the mechanisms leading to the two-equinox maxima pattern are in operation, the long-term change of solar wind speed tends to mask the effect of these mechanisms for individual years. Large cycle-to-cycle variation is found in the seasonal pattern: equinox maxima are more common during cycles 21 and 22 than in cycles 23 or 24. Exceptionally long winter dominance in high-latitude activity and solar wind speed is seen in the declining phase of cycle 23, after the appearance of the long-lasting low-latitude coronal hole.

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.

Flares, Fears, and Forecasts: Public Misconceptions About the Sunspot Cycle

NASA Astrophysics Data System (ADS)

Larsen, K.

2012-06-01

Among the disaster scenarios perpetrated by 2012 apocalypse aficionados is the destruction of humankind due to solar flares and coronal mass ejections (CMEs). These scenarios reflect common misconceptions regarding the solar cycle. This paper (based on an annual meeting poster) sheds light on those misconceptions and how the AAVSO Solar Section can address them.

24/7 Solar Minimum Polar Cap and Auroral Ion Temperature Observations

NASA Technical Reports Server (NTRS)

Sojka, Jan J.; Nicolls, Michael; van Eyken, Anthony; Heinselman, Craig; Bilitza, Dieter

2011-01-01

During the International Polar Year (IPY) two Incoherent Scatter Radars (ISRs) achieved close to 24/7 continuous observations. This presentation describes their data sets and specifically how they can provide the International Reference Ionosphere (IRI) a fiduciary E- and F-region ionosphere description for solar minimum conditions in both the auroral and polar cap regions. The ionospheric description being electron density, ion temperature and electron temperature profiles from as low as 90 km extending to several scale heights above the F-layer peak. The auroral location is Poker Flat in Alaska at 65.1 N latitude, 212.5 E longitude where the NSF s new Poker Flat Incoherent Scatter Radar (PFISR) is located. This location during solar minimum conditions is in the auroral region for most of the day but is at midlatitudes, equator ward of the cusp, for about 4-8 h per day dependent upon geomagnetic activity. In contrast the polar location is Svalbard, at 78.2 N latitude, 16.0 E longitude where the EISCAT Svalbard Radar (ESR) is located. For most of the day the ESR is in the Northern Polar Cap with a noon sector passage often through the dayside cusp. Of unique relevance to IRI is that these extended observations have enabled the ionospheric morphology to be distinguished between quiet and disturbed geomagnetic conditions. During the IPY year, 1 March 2007 - 29 February 2008, about 50 solar wind Corotating Interaction Regions (CIRs) impacted geospace. Each CIR has a two to five day geomagnetic disturbance that is observed in the ESR and PFISR observations. Hence, this data set also enables the quiet-background ionospheric climatology to be established as a function of season and local time. These two separate climatologies for the ion temperature at an altitude of 300 km are presented and compared with IRI ion temperatures. The IRI ion temperatures are about 200-300 K hotter than the observed values. However, the MSIS neutral temperature at 300 km compares favorably with the quiet-background in temperature, both in magnitude and climatology.

NASA welding assessment program

NASA Technical Reports Server (NTRS)

Stofel, E. J.

1984-01-01

A long duration test was conducted for comparing various methods of attaching electrical interconnects to solar cells for near Earth orbit spacecraft. Representative solar array modules were thermally cycled for 36,000 cycles between -80 and +80 C. The environmental stress of more than 6 years on a near Earth spacecraft as it cycles in and out of the earth's shadow was simulated. Evaluations of the integrity of these modules were made by visual and by electrical examinations before starting the cycling and then at periodic intervals during the cycling tests. Modules included examples of parallel gap and of ultrasonic welding, as well as soldering. The materials and fabrication processes are state of the art, suitable for forming large solar arrays of spacecraft quality. The modules survived this extensive cycling without detectable degradation in their ability to generate power under sunlight illumination.

Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

1987-01-01

Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

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.

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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

Examination of the Armagh Observatory Annual Mean Temperature Record, 1844-2004

NASA Technical Reports Server (NTRS)

Wilson, Robert M.; Hathaway, David H.

2006-01-01

The long-term annual mean temperature record (1844-2004) of the Armagh Observatory (Armagh, Northern Ireland, United Kingdom) is examined for evidence of systematic variation, in particular, as related to solar/geomagnetic forcing and secular variation. Indeed, both are apparent in the temperature record. Moving averages for 10 years of temperature are found to highly correlate against both 10-year moving averages of the aa-geomagnetic index and sunspot number, having correlation coefficients of approx. 0.7, inferring that nearly half the variance in the 10-year moving average of temperature can be explained by solar/geomagnetic forcing. The residuals appear episodic in nature, with cooling seen in the 1880s and again near 1980. Seven of the last 10 years of the temperature record has exceeded 10 C, unprecedented in the overall record. Variation of sunspot cyclic averages and 2-cycle moving averages of temperature strongly associate with similar averages for the solar/geomagnetic cycle, with the residuals displaying an apparent 9-cycle variation and a steep rise in temperature associated with cycle 23. Hale cycle averages of temperature for even-odd pairs of sunspot cycles correlate against similar averages for the solar/geomagnetic cycle and, especially, against the length of the Hale cycle. Indications are that annual mean temperature will likely exceed 10 C over the next decade.

The solar energetic particle propagation of solar flare events on 24th solar cycle.

NASA Astrophysics Data System (ADS)

Paluk, P.; Khumlumlert, T.; Kanlayaprasit, N.; Aiemsa-ad, N.

2017-09-01

Now the Sun is in the 24th solar cycle. The peak of solar cycle correspond to the number of the Sun activities, which one of them is solar flare. The solar flare is the violent explosion at the solar atmosphere and releases the high energy ion from the Sun to the interplanetary medium. Solar energetic particles or solar cosmic ray have important effect on the Earth, such as disrupt radio communication. We analyze the particle transport of the solar flare events on August 9, 2011, January 27, 2012, and November 3, 2013 in 24th solar cycle. The particle data for each solar flare was obtained from SIS instrument on ACE spacecraft. We simulate the particle transport with the equation of Ruffolo 1995, 1998. We solve the transport equation with the numerical technique of finite different. We find the injection duration from the Sun to the Earth by the compared fitting method of piecewise linear function between the simulation results and particle data from spacecraft. The position of these solar flare events are on the west side of the Sun, which are N18W68, N33W85, and S12W16. We found that mean free path is roughly constant for a single event. This implies that the interplanetary scattering is approximately energy independent, but the level of scattering varies with time. The injection duration decreases with increasing energy. We found the resultant variation of the highest energy and lowest energy, because the effect of space environments and the number of the detected data was small. The high mean free path of the high energy particles showed the transport capability of particles along to the variable magnetic field line. The violent explosion of these solar flares didn’t affect on the Earth magnetic field with Kp-index less than 3.

Statistical Comparison of Anomalous Cosmic Rays and Galactic Cosmic Rays during the Recently Consecutive Unusual Solar Cycles

NASA Astrophysics Data System (ADS)

Zhao, L.; Zhang, H.

2014-12-01

Anomalous cosmic rays (ACRs) carry crucial information on the coupling between solar wind and interstellar medium, as well as cosmic ray modulation within the heliosphere. Due to the distinct origins and modulation processes, the spectra and abundance of ACRs are significantly different from that of galactic cosmic rays (GCRs). Since the launch of NASA's ACE spacecraft in 1997, its CRIS and SIS instruments have continuously recorded GCR and ACR intensities of several elemental heavy-ions, spanning the whole cycle 23 and the cycle 24 maximum. Here we present a statistical comparison of ACR and GCR observed by ACE spacecraft and their possible relation to solar activity. While the differential flux of ACR also exhibits apparent anti-correlation with solar activity level, the flux of the latest prolonged solar minimum (year 2009) is approximately 5% lower than its previous solar minimum (year 1997). And the minimal level of ACR flux appears in year 2004, instead of year 2001 with the strongest solar activities. The negative indexes of the power law spectra within the energy range from 5 to 30 MeV/nuc also vary with time. The spectra get harder during the solar minimum but softer during the solar maximum. The approaching solar minimum of cycle 24 is believed to resemble the Dalton or Gleissberg Minimum with extremely low solar activity (Zolotova and Ponyavin, 2014). Therefore, the different characteristics of ACRs between the coming solar minimum and the previous minimum are also of great interest. Finally, we will also discuss the possible solar-modulation processes which is responsible for different modulation of ACR and GCR, especially the roles played by diffusion and drifts. The comparative analysis will provide valuable insights into the physical modulation process within the heliosphere under opposite solar polarity and variable solar activity levels.

Solar and Galactic Cosmic Rays Observed by SOHO

NASA Astrophysics Data System (ADS)

Fleck, Bernhard; Curdt, Werner; Olive, Jean-Philippe; van Overbeek, Ton

2015-04-01

Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to 75% of its original level over 1 ½ solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mechanism. We compare the daily CRF observed by the Oulu station with the daily SOHO SEU rate and with the degradation curve of the solar arrays. The Oulu CRF and the SOHO SSR SEU rate are both modulated by the solar cycle and are highly correlated, except for sharp spikes in the SEU rate, caused by isolated SEP events, which also show up as discontinuities in the otherwise slowly decreasing solar ray efficiency. This allows to discriminate between effects with solar and non-solar origin and to compare the relative strength of both. We find that the total number of SSR SEUs with solar origin over the 17 ½ years from January 1996 through June 2013 is of the same order as those generated by cosmic ray hits. 49% of the total solar array degradation during that time can be attributed to proton events, i.e. the effect of a series of short-lived, violent events (SEPs) is comparable to the cycle-integrated damage by cosmic rays.

Properties of sunspot cycles and hemispheric wings since the 19th century

NASA Astrophysics Data System (ADS)

Leussu, Raisa; Usoskin, Ilya G.; Arlt, Rainer; Mursula, Kalevi

2016-08-01

Aims: The latitudinal evolution of sunspot emergence over the course of the solar cycle, the so-called butterfly diagram, is a fundamental property of the solar dynamo. Here we present a study of the butterfly diagram of sunspot group occurrence for cycles 7-10 and 11-23 using data from a recently digitized sunspot drawings by Samuel Heinrich Schwabe in 1825-1867, and from RGO/USAF/NOAA(SOON) compilation of sunspot groups in 1874-2015. Methods: We developed a new, robust method of hemispheric wing separation based on an analysis of long gaps in sunspot group occurrence in different latitude bands. The method makes it possible to ascribe each sunspot group to a certain wing (solar cycle and hemisphere), and separate the old and new cycle during their overlap. This allows for an improved study of solar cycles compared to the common way of separating the cycles. Results: We separated each hemispheric wing of the butterfly diagram and analysed them with respect to the number of groups appearing in each wing, their lengths, hemispheric differences, and overlaps. Conclusions: The overlaps of successive wings were found to be systematically longer in the northern hemisphere for cycles 7-10, but in the southern hemisphere for cycles 16-22. The occurrence of sunspot groups depicts a systematic long-term variation between the two hemispheres. During Schwabe time, the hemispheric asymmetry was north-dominated during cycle 9 and south-dominated during cycle 10.

SSBUV and NOAA-11 SBUV/2 Solar Variability Measurements

NASA Technical Reports Server (NTRS)

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

1998-01-01

The Shuttle SBUV (SSBUV) and NOAA-11 SBUV/2 instruments measured solar spectral UV irradiance during the maximum and declining phase of solar cycle 22. The SSB UV data accurately represent the absolute solar UV irradiance between 200-405 nm, and also show the long-term variations during eight flights between October 1989 and January 1996. These data have been used to correct long-term sensitivity changes in the NOAA-11 SBUV/2 data, which provide a near-daily record of solar UV variations over the 170-400 nm region between December 1988 and October 1994. The NOAA-11 data demonstrate the evolution of short-term solar UV activity during solar cycle 22.

AFT: Extending Solar Cycle Prediction with Data Assimilation

NASA Astrophysics Data System (ADS)

Upton, L.; Hathaway, D. H.

2017-12-01

The Advective Flux Transport (AFT) model is an innovative surface flux transport model that simulates the evolution of the radial magnetic field on the surface of the Sun. AFT was designed to be as realistic as possible by 1: incorporating the observed surface flows (meridional flow, differential rotation, and an explicit evolving convective pattern) and by 2: using data assimilation to incorporate the observed magnetic fields directly from line-of-sight (LOS) magnetograms. AFT has proven to be successful in simulating the evolution of the surface magnetic fields on both short time scales (days-weeks) as well as for long time scales (years). In particular, AFT has been shown to accurately predict the evolution of the Sun's dipolar magnetic field 3-5 years in advance. Since the Sun's polar magnetic field strength at solar cycle minimum is the best indicator of the amplitude of the next cycle, this has in turn extended our ability to make solar cycle predictions to 3-5 years before solar minimum occurs. Here, we will discuss some of the challenges of implementing data assimilation into AFT. We will also discuss the role of data assimilation in advancing solar cycle predictive capability.

Electrostatic bonding of thin (cycle sine 3 mil) 7070 cover glass to Ta2O5 AR-coated thin (cycle sine 2 mil) silicon wafers and solar cells

NASA Technical Reports Server (NTRS)

Egelkrout, D. W.

1981-01-01

Electrostatic bonding of thin cover glass to thin solar cells was researched. Silicon solar cells, wafers, and Corning 7070 glass of from about 0.002" to about 0.003" in thickness were used in the investigation to establish optimum parameters for producing mechanically acceptable bonds while minimizing thermal stresses and resultant solar cell electrical parameter degradation.

Spring-fall asymmetry of substorm strength, geomagnetic activity and solar wind: Implications for semiannual variation and solar hemispheric asymmetry

USGS Publications Warehouse

Marsula, K.; Tanskanen, E.; Love, J.J.

2011-01-01

We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993–2008. The number of substorms and substorm mean duration depict an annual variation with maxima in Winter and Summer, respectively, reflecting the annual change of the local ionosphere. In contradiction, substorm mean amplitude, substorm total efficiency and global geomagnetic activity show a dominant annual variation, with equinoctial maxima alternating between Spring in solar cycle 22 and Fall in cycle 23. The largest annual variations were found in 1994 and 2003, in the declining phase of the two cycles when high-speed streams dominate the solar wind. A similar, large annual variation is found in the solar wind driver of substorms and geomagnetic activity, which implies that the annual variation of substorm strength, substorm efficiency and geomagnetic activity is not due to ionospheric conditions but to a hemispherically asymmetric distribution of solar wind which varies from one cycle to another. Our results imply that the overall semiannual variation in global geomagnetic activity has been seriously overestimated, and is largely an artifact of the dominant annual variation with maxima alternating between Spring and Fall. The results also suggest an intimate connection between the asymmetry of solar magnetic fields and some of the largest geomagnetic disturbances, offering interesting new pathways for forecasting disturbances with a longer lead time to the future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, N. B.; Kong, D. F., E-mail: nanbin@ynao.ac.cn

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-cyclemore » 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.« less

An early prediction of 25th solar cycle using Hurst exponent

NASA Astrophysics Data System (ADS)

Singh, A. K.; Bhargawa, Asheesh

2017-11-01

The analysis of long memory processes in solar activity, space weather and other geophysical phenomena has been a major issue even after the availability of enough data. We have examined the data of various solar parameters like sunspot numbers, 10.7 cm radio flux, solar magnetic field, proton flux and Alfven Mach number observed for the year 1976-2016. We have done the statistical test for persistence of solar activity based on the value of Hurst exponent (H) which is one of the most classical applied methods known as rescaled range analysis. We have discussed the efficiency of this methodology as well as prediction content for next solar cycle based on long term memory. In the present study, Hurst exponent analysis has been used to investigate the persistence of above mentioned (five) solar activity parameters and a simplex projection analysis has been used to predict the ascension time and the maximum number of counts for 25th solar cycle. For available dataset of the year 1976-2016, we have calculated H = 0.86 and 0.82 for sunspot number and 10.7 cm radio flux respectively. Further we have calculated maximum number of counts for sunspot numbers and F10.7 cm index as 102.8± 24.6 and 137.25± 8.9 respectively. Using the simplex projection analysis, we have forecasted that the solar cycle 25th would start in the year 2021 (January) and would last up to the year 2031 (September) with its maxima in June 2024.

The Complexity of Solar and Geomagnetic Indices

NASA Astrophysics Data System (ADS)

Pesnell, W. Dean

2017-08-01

How far in advance can the sunspot number be predicted with any degree of confidence? Solar cycle predictions are needed to plan long-term space missions. Fleets of satellites circle the Earth collecting science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Statistical and timeseries analyses of the sunspot number are often used to predict solar activity. These methods have not been completely successful as the solar dynamo changes over time and one cycle's sunspots are not a faithful predictor of the next cycle's activity. In some ways, using these techniques is similar to asking whether the stock market can be predicted. It has been shown that the Dow Jones Industrial Average (DJIA) can be more accurately predicted during periods when it obeys certain statistical properties than at other times. The Hurst exponent is one such way to partition the data. Another measure of the complexity of a timeseries is the fractal dimension. We can use these measures of complexity to compare the sunspot number with other solar and geomagnetic indices. Our concentration is on how trends are removed by the various techniques, either internally or externally. Comparisons of the statistical properties of the various solar indices may guide us in understanding how the dynamo manifests in the various indices and the Sun.

SBUV/2 Long-Term Measurements of Solar Spectral Variability

NASA Technical Reports Server (NTRS)

DeLand, Matthew T.; Cebula, Richard P.

1997-01-01

The NOAA-11 SBUV/2 spectral solar data have been corrected for long-term instrument changes to produce a 5.5 year data record during solar cycle 22 (December 1988 - October 1994). Residual drifts in the data at long wavelengths are +/- 1% or less. At 200-205 nm, where solar variations drive stratospheric photochemistry, these data indicate long-term solar changes of 5-7% from the maximum of Cycle 22 in April 1991 through the end of the NOAA-11 data record. Comparisons of NOAA-11 data with UARS SUSIM and SOLSTICE for the period October 1991 - October 1994, when all 3 instruments were operating simultaneously, show that the observed long-term variations in 200-205 nm irradiance agree to within 2%. This result is consistent with predictions from the Mg-2 proxy index. The SBUV/2 instruments represent a valuable resource for long-term solar UV activity studies because of their overlapping data records. In addition to the NOAA-11 data presented here, the NOAA-9 SBUV/2 instrument began taking data in March 1985 and is still operating, providing a complete record of Cycle 22 behavior from a single instrument. Three additional SBUV/2 instruments are scheduled to be launched between 1997 and 2003, which should permit full coverage of solar cycle 23.

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.

MAVEN Upstream Observations of the Cycle 24 Space Weather Conditions at Mars

NASA Astrophysics Data System (ADS)

Lee, C. O.; Hara, T.; Halekas, J. S.; Thiemann, E.; Curry, S.; Lillis, R. J.; Larson, D. E.; Espley, J. R.; Gruesbeck, J.; Eparvier, F. G.; Li, Y.; Jian, L.; Luhmann, J. G.; Jakosky, B. M.

2016-12-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft went into orbit around Mars during the height of the activity phase of Solar Cycle 24. The mission was designed in part to study the response of the upper atmosphere, ionosphere, and magnetosphere of Mars to solar and solar wind inputs. When MAVEN is on the Martian dayside and orbiting around its apoapsis altitude of 6200 km, the suite of instruments onboard can measure the solar wind plasma (density, velocity), interplanetary magnetic field (magnitude and direction), and particle counts of solar energetic particles (SEPs), as well as the EUV solar irradiance. We will present an overview of the upstream conditions observed to date and highlight a number of Mars-impacting space weather events due to ICMEs and SEPs. We will also present events that are triggered by corotating interaction regions (CIRs), which become more prominent beyond 1 AU and are the dominant heliospheric structures during the declining phase of the solar cycle. As part of the discussion, we will compare and contrast observations from MAVEN and ACE/WIND or STEREO-A during periods when Mars and the 1-AU observer were in solar opposition or nearly aligned along the solar wind Parker spiral.