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Sample records for quiet solar intranetwork

  1. Solar Intranetwork Magnetic Elements: Flux Distributions

    NASA Astrophysics Data System (ADS)

    Zhou, Guiping; Wang, Jingxiu; Jin, Chunlan

    2013-04-01

    The current study aims at quantifying the flux distributions of solar intranetwork (IN) magnetic field based on the data taken in four quiet and two enhanced network areas with the Narrow-band Filter Imager of the Solar Optical Telescope on board the Hinode satellite. More than 14000 IN elements and 3000 NT elements were visually identified. They exhibit a flux distribution function with a peak at 1 - 3×1016 Mx (maxwell) and 2 - 3×1017 Mx, respectively. We found that the IN elements contribute approximately to 52 % of the total flux and an average flux density of 12.4 gauss of the quiet region at any given time. By taking the lifetime of IN elements of about 3 min (Zhou et al., Solar Phys. 267, 63, 2010) into account, the IN fields are estimated to have total contributions to the solar magnetic flux up to 3.8×1026 Mx per day. No fundamental distinction can be identified in IN fields between the quiet and enhanced network areas.

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

    SciTech Connect

    Jin, C. L.; Wang, J. X.

    2015-07-01

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

  3. Substorm occurrence during quiet solar wind driving

    NASA Astrophysics Data System (ADS)

    Pulkkinen, T. I.; Partamies, N.; Kilpua, E. K. J.

    2014-04-01

    We examine the OMNI database and International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer chain records to study the substorm occurrence and characteristics during quiet solar driving periods, especially during the solar minimum period in 2009. We define substorm-like activations as periods where the hourly average AL is below -200 nT. Using the OMNI data set, we demonstrate that there are limiting solar wind speed, interplanetary magnetic field magnitude, and driving electric field values below which substorm-like activations (AL < 200 nT, intensification and decay of the electrojet) do not occur. These minimum parameter values are V < 266 km/s, B < 1.4 nT, and E < 0.025 mV/m such low values are observed less than 1% of the time. We also show that for the same level of driving solar wind electric field, the electrojet intensity is smaller (by few tens of nT), and the electrojet resides farther poleward (by over 1°) during extended quiet solar driving in 2009 than during average solar activity conditions. During the solar minimum period in 2009, we demonstrate that substorm-like activations can be identified from the IMAGE magnetometer chain observations during periods when the hourly average IL index is below -100 nT. When the hourly IL activity is smaller than that, which covers 87% of the nighttime observations, the electrojet does not show coherent behavior. We thus conclude that substorm recurrence time during very quiet solar wind driving conditions is about 5-8 h, which is almost double that of the average solar activity conditions.

  4. Reconnection brightenings in the quiet solar photosphere

    NASA Astrophysics Data System (ADS)

    Rouppe van der Voort, Luc H. M.; Rutten, Robert J.; Vissers, Gregal J. M.

    2016-08-01

    We describe a new quiet-Sun phenomenon which we call quiet-Sun Ellerman-like brightenings (QSEB). QSEBs are similar to Ellerman bombs (EB) in some respects but differ significantly in others. EBs are transient brightenings of the wings of the Balmer Hα line that mark strong-field photospheric reconnection in complex active regions. QSEBs are similar but smaller and less intense Balmer-wing brightenings that occur in quiet areas away from active regions. In the Hα wing, we measure typical lengths of less than 0.5 arcsec, widths of 0.23 arcsec, and lifetimes of less than a minute. We discovered them using high-quality Hα imaging spectrometry from the Swedish 1-m Solar Telescope (SST) and show that, in lesser-quality data, they cannot be distinguished from more ubiquitous facular brightenings, nor in the UV diagnostics currently available from space platforms. We add evidence from concurrent SST spectropolarimetry that QSEBs also mark photospheric reconnection events, but in quiet regions on the solar surface. The movies are available in electronic form at http://www.aanda.org

  5. The Temperature and Density Structure of the Quiet Solar Corona

    NASA Astrophysics Data System (ADS)

    Winebarger, A. R.; Warren, H. P.

    2001-05-01

    The temperature and density structure of the quiet solar corona remains unclear. In this poster, we will present a preliminary analysis of a quiet solar coronal loop structure observed with SOHO and TRACE. After determining the magnetic field structure from potential field extrapolation, we attempt to model this loop using RTV scaling laws with various heating functions. This work is in preparation for a full-scale statistical study of SOHO/TRACE data to determine the structure of the quiet solar corona.

  6. The heating of the quiet solar chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang

    1990-01-01

    The quiet solar chromosphere shows three distinct regions. Ordered according to the strength of the emission from the low and middle chromosphere they are (1) the magnetic elements on the boundary of supergranulation cells, (2) the bright points in the cell interior, and (3) the truly quiet chromosphere, also in the cell interior. The magnetic elements on the cell boundary are associated with intense magnetic fields and are heated by waves with very long periods, ranging from six to twelve minutes; the bright points are associated with magnetic elements of low field strength and are heated by (long-period) waves with periods near the acoustic cutoff period of three minutes; and the quiet cell interior, which is free of magnetic field, may be heated by short-period acoustic waves, with periods below one minute. This paper reviews mainly the heating of the bright points and concludes that the large-amplitude, long-period waves heating the bright points dissipate enough energy to account for their chromospheric temperature structure.

  7. The heating of the quiet solar chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang

    1990-01-01

    The quiet solar chromosphere shows three distinct regions. Ordered according to the strength of the emission from the low and middle chromosphere they are (1) the magnetic elements on the boundary of supergranulation cells, (2) the bright points in the cell interior, and (3) the truly quiet chromosphere, also in the cell interior. The magnetic elements on the cell boundary are associated with intense magnetic fields and are heated by waves with very long periods, ranging from six to twelve minutes; the bright points are associated with magnetic elements of low field strength and are heated by (long-period) waves with periods near the acoustic cutoff period of three minutes; and the quiet cell interior, which is free of magnetic field, may be heated by short-period acoustic waves, with periods below one minute. This paper reviews mainly the heating of the bright points and concludes that the large-amplitude, long-period waves heating the bright points dissipate enough energy to account for their chromospheric temperature structure.

  8. Correcting solar quiet variations for tidal signals

    NASA Astrophysics Data System (ADS)

    Guzavina, Martina; Grayver, Alexander; Kuvshinov, Alexey

    2017-04-01

    Solar quiet (Sq) variations of geomagnetic field are originated from electric current system which is flowing at 110 km altitude in a thin ionospheric E-layer. This current system is driven by atmospheric tides in the ambient magnetic field of the Earth. These tides are generated from solar heating of the atmosphere on the sunlit side of Earth. Sq variations are periodic phenomenon and thus can be represented as a superposition of time harmonics with periods of 24, 12, 8, 6, 4.8 and 4 hours. These variations can be used for electromagnetic induction sounding to study electrical conductivity of the Earth's upper mantle down to approximately 600 km. However, Sq variations are potentially distorted by several factors. Among them are motionally-induced (tidal) magnetic signals which have periods close to 12 and 24 hours. This study is aimed at evaluating and correcting for the effect of tidal magnetic signals in observed Sq variations.

  9. Multiwavelength analysis of a solar quiet region

    NASA Astrophysics Data System (ADS)

    Tsiropoula, G.; Tziotziou, K.; Schwartz, P.; Heinzel, P.

    2009-01-01

    Context: We examine oscillatory phenomena in a solar network region from multi-wavelength observations obtained by the ground-based Dutch Open Telescope (DOT) and by the Coronal Diagnostic Spectrometer (CDS) on the spacecraft Solar and Heliospheric Observatory (SoHO). The observations were obtained during a coordinated observing campaign in October 2005. Aims: We investigate the temporal variations of the intensities and the velocities in two distinct regions of the quiet Sun, one containing several dark mottles and the other several bright points defining the network boundaries (NB). The aim is to find similarities and/or differences in the oscillatory phenomena observed in these two regions and in different spectral lines formed from the chromosphere to the transition region, as well as the propagation characteristics of waves. Methods: Intensity and velocity variations are studied with wavelet and phase difference analyses. Results: Both regions (i.e. mottles and NB) show a periodicity of ~5 min in all considered lines. The V-V phase differences in the NB region point to an upward propagation of waves; in the region of mottles, for periods of 250-400 s, the phase difference is mainly negative, which suggests a downward propagation, in turn indicating a refraction of waves from the inclined magnetic field of mottles along the line-of-sight. Conclusions: The phase differences at the NB arise from a predominance of upward propagating waves. In the mottles' region, the negative phase differences we found suggest that propagating waves encounter a boundary and are refracted and reflected. Of course, several limitations exist in the exact interpretation of the phase differences, e.g. the complex topology of the magnetic field, the formation conditions and heights of the examined spectral lines, and the low spatial resolution.

  10. Multi-wavelength Analysis of a Quiet Solar Region

    NASA Astrophysics Data System (ADS)

    Tsiropoula, G.; Tziotziou, K.; Giannikakis, J.; Young, P.; Schühle, U.; Heinzel, P.

    2007-05-01

    We present observations of a solar quiet region obtained by the ground-based Dutch Open Telescope (DOT), and by instruments on the spacecraft SOHO and TRACE. The observations were obtained during a coordinated observing campaign on October 2005. The aim of this work is to present the rich diversity of fine-scale structures that are found at the network boundaries and their appearance in different instruments and different spectral lines that span the photosphere to the corona. Detailed studies of these structures are crucial to understanding their dynamics in different solar layers, as well as the role such structures play in the mass balance and heating of the solar atmosphere.

  11. Energy and helicity injection in solar quiet regions

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.; Park, S.-H.; Tsiropoula, G.; Kontogiannis, I.

    2015-09-01

    Aims: We investigate the free magnetic energy and relative magnetic helicity injection in solar quiet regions. Methods: We use the DAVE4VM method to infer the photospheric velocity field and calculate the free magnetic energy and relative magnetic helicity injection rates in 16 quiet-Sun vector magnetograms sequences. Results: We find that there is no dominant sense of helicity injection in quiet-Sun regions, and that both helicity and energy injections are mostly due to surface shuffling motions that dominate the respective emergence by factors slightly larger than two. We, furthermore, estimate the helicity and energy rates per network unit area as well as the respective budgets over a complete solar cycle. Conclusions: Derived helicity and energy budgets over the entire solar cycle are similar to respective budgets derived in a recent work from the instantaneous helicity and free magnetic energy budgets and higher than previously reported values that relied on similar approaches to this analysis. Free-energy budgets, mostly generated like helicity at the network, are high enough to power the dynamics of fine-scale structures residing at the network, such as mottles and spicules, while corresponding estimates of helicity budgets are provided, pending future verification from high-resolution magneto-hydrodynamic simulations and/or observations.

  12. A theory of heating of quiet solar corona

    SciTech Connect

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2015-03-15

    A theory is proposed to discuss the creation of hot solar corona. We pay special attention to the transition region and the low corona, and consider that the sun is quiet. The proposed scenario suggests that the protons are heated by intrinsic Alfvénic turbulence, while the ambient electrons are heated by the hot protons via collisions. The theory contains two prime components: the generation of the Alfvénic fluctuations by the heavy minor ions in the transition region and second, the explanation of the temperature profile in the low solar atmosphere. The proposed heating process operates continuously in time and globally in space.

  13. Temperatures of the disturbed and quiet inner solar corona

    SciTech Connect

    Nikol'skaya, K.I.

    1985-05-01

    The temperature composition of four coronal disturbances (CD) and the quiet inner corona of different epochs is investigated on the basis of eclipse observations of the coronal optical spectrum within the framework of concepts of the solar corona in quiet and active regions as consisting of elementary arches of different temperatures containing material of the same density. Three of the CD consisted of two components, a hot coronal condensation (a Ca XV region) with T/sub e/roughly-equal3.8 x 10/sup 6/ K and an Ni XV region with T/sub e/roughly-equal2.3 x 10/sup 6/ K; the contribution of the former to the total CD emission was from 14 to 23% while the weighted-mean temperature was T/sub e/ = (2.5--2.6) x 10/sup 6/ K. Two of the CD (Feb. 25, 1952, and July 31, 1981) had an identical temperature composition, despite the difference in their spectra and other characteristics. Considerable spatial variations of temperature composition occur in the quiet inner corona. On the average, Fe XIV regions (T/sub e/ = 1.9 x 10/sup 6/ K) dominate in approx.1/3 of the undisturbed corona in the minimum phase and Ni XV regions (T/sub e/ = 2.3 x 10/sup 6/ K) dominate in approx.2/3, while the average temperature composition lies in the range of Ni XV:Fe XIV:Fe X = (0.42:0.38:0.20) -(0.78:0.18:0.04). Variations of the average temperature composition of the quiet corona with the solar activity cycle are traced: The fraction of the Ni XV region grows from 0.60 at the minimum to 0.83 at the maximum with variation of the weighted-mean temperature from 2.1 x 10/sup 6/ to 2.2 x 10/sup 6/ K.

  14. Limits to the Radiative Asymmetry of the Quiet Solar Disk

    NASA Astrophysics Data System (ADS)

    Livingston, W.; Sheeley, N. R., Jr.

    2008-01-01

    Precise data on the uniformity of photospheric radiation over the solar disk seems not to exist. Such information is necessary to separate the radiative behavior of the quiet basal atmosphere from the active (magnetic) atmosphere. Is the latter the sole source of known irradiance variation? How uniform can a solar-like stellar disk be? To obtain this information we have made monochromatic scans along the central meridian of the quiet Sun using single element detectors which do not require flat fielding. The scans were in continua and in selected Fraunhofer lines ranging from 3134 to 46880 Å the observational epoch was near solar minimum: 2006 October to 2007 February. The meridian was chosen to avoid rotational Doppler shifts. We extract the asymmetry between the north and south hemispheres and present it as our main product. In the near-infrared and visible continuum, averaging over granulation and avoiding sunspots, we found that such asymmetry was as low as 0.05% (at 34168 Å on 2007 February 8). In the violet and ultraviolet this asymmetry typically increases to 1%. Asymmetry is larger in the cores of the medium strong photospheric and chromospheric lines, which refer to higher levels in the atmosphere, and may reach 15%. The contrast of faculae increases in the blue (and with improved spatial resolution or seeing), and is the probable source for the measured asymmetries. We also find that line core scans are in general flatter than continuum scans.

  15. Solar extreme ultraviolet variability of the quiet Sun

    NASA Astrophysics Data System (ADS)

    Shakeri, F.; Teriaca, L.; Solanki, S. K.

    2015-09-01

    The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the total solar irradiance during the minimum after cycle 23 may have dropped below the values known from the two minima prior to that. For chromospheric and coronal radiation, the situation is less clear-cut. The Sun's 10.7 cm flux shows a decrease of ~4% during the solar minimum in 2008 compared to the previous minimum, but Ca ii K does not. Here we consider additional wavelengths in the extreme ultraviolet (EUV), specifically transitions of He i at 584.3 Å and O v at 629.7 Å, of which the CDS spectrometer aboard SOHO has been taking regular scans along the solar central meridian since 1996. We analysed this unique dataset to verify if and how the radiance distribution undergoes measurable variations between cycle minima. To achieve this aim we determined the radiance distribution of quiet areas around the Sun centre. Concentrating on the last two solar minima, we found out that there is very little variation in the radiance distribution of the chromospheric spectral line He i between these minima. The same analysis shows a modest, although significant, 4% variation in the radiance distribution of the TR spectral line O v. These results are comparable to those obtained by earlier studies employing other spectral features, and they confirm that chromospheric indices display a small variation, whereas in the transition region a more significant reduction of the brighter features is visible.

  16. MWA Observations of Solar Radio Bursts and the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Cairns, I.; Oberoi, D.; Morgan, J.; Bastian, T.; Bhatnagar, S.; Bisi, M.; Benkevitch, L.; Bowman, J.; Donea, A.; Giersch, O.; Jackson, B.; Chat, G. L.; Golub, L.; Hariharan, K.; Herne, D.; Kasper, J.; Kennewell, J.; Lonsdale, C.; Lobzin, V.; Matthews, L.; Mohan, A.; Padmanabhan, J.; Pankratius, V.; Pick, M.; Subramanian, P.; Ramesh, R.; Raymond, J.; Reeves, K.; Rogers, A.; Sharma, R.; Tingay, S.; Tremblay, S.; Tripathi, D.; Webb, D.; White, S.; Abidin, Z. B. Z.

    2017-01-01

    A hundred hours of observing time for solar observations is requested during the 2017-A observing semester. These data will be used to address science objectives for solar burst science (Goal A), studies of weak non-thermal radiation (Goal B) and quiet sun science (Goal C). Goal A will focus on detailed investigations of individual events seen in the MWA data, using the unsurpassed spectroscopic imaging ability of the MWA to address some key solar physics questions. Detailed observations of type II bursts, of which MWA has observed two, will be one focus, with MWA polarimetric imaging observations of type III bursts another focus. Goal B will address studies of the numerous short lived and narrow band emission features, significantly weaker than those seen by most other instruments revealed by the MWA. These emission features do not resemble any known types of solar bursts, but are possible signatures of "nanoflares" which have long been suspected to play a role in coronal heating. A large database of these events is needed to be able to reliably estimate their contribution to coronal heating. These observations will contribute to this database. Goal C will focus on characterizing the Sun's background thermal emission, their short and long term variability and looking for evidence of a scattering disc around the Sun.

  17. Shocks in the Quiet Solar Photosphere: A Rather Common Occurrence

    NASA Astrophysics Data System (ADS)

    Socas-Navarro, H.; Manso Sainz, R.

    2005-02-01

    We present observations of the quiet solar photosphere in the Fe I lines at 6302 Å where at least four different spatial locations exhibit upward-directed supersonic flows. These upflows can only be detected in the circular polarization profiles as a double-peaked structure in the blue lobe of both Fe I lines. We have detected cases of either magnetic polarity in the data. The polarization signals associated with the upflows are very weak, which is probably why they had not been seen before in this type of observation. We propose that the observed flows are the signature of aborted convective collapse, similar to the case reported by Bellot Rubio et al. Our data indicate that this phenomenon occurs frequently in the quiet Sun, which means that many magnetic elements (although the fraction is still unknown) are destroyed even before they are formed completely. The spectral signatures of supersonic upflows reported here are probably present in most spectropolarimetric observations of sufficient signal-to-noise ratio and spatial resolution.

  18. Energy distribution of nanoflares in the quiet solar corona

    NASA Astrophysics Data System (ADS)

    Ulyanov, Artyom

    2012-07-01

    We present a detailed statistical analysis of flare-like events in low layer of solar corona detected with TESIS instrument onboard CORONAS-PHOTON satellite in 171 {Å} during high-cadence (5 sec) time-series. The estimated thermal energies of these small events amount to 10^{23} - 10^{26} erg. According to modern classification flare-like events with such energies are usually referred to as nanoflares. The big number of registered events (above 2000) allowed us to obtain precise distributions of geometric and physical parameters of nanoflares, the most intriguing being energy distribution. Following Aschwanden et al. (2000) and other authors we approximated the calculated energy distribution with a single power law slope: N(E)dE ˜ N^{-α}dE. The power law index was derived to be α = 2.4 ± 0.2, which is very close to the value reported by Krucker & Benz (1998): α ≈ 2.3 - 2.4. The total energy input from registered events constitute about 10^4 erg \\cdot cm^{-2} \\cdot s^{-1}, which is well beyond net losses in quiet corona (3 \\cdot 10^5 erg \\cdot cm^{-2} \\cdot s^{-1}). However, the value of α > 2 indicates that nanoflares with lower energies dominate over nanoflares with bigger energies and could contribute considerably to quiet corona heating.

  19. Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona

    NASA Technical Reports Server (NTRS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2014-01-01

    Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvenic interactions.

  20. Spatiotemporal organization of energy release events in the quiet solar corona

    SciTech Connect

    Uritsky, Vadim M.; Davila, Joseph M.

    2014-11-01

    Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvénic interactions.

  1. Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona

    NASA Technical Reports Server (NTRS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2014-01-01

    Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvenic interactions.

  2. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William J. (Technical Monitor)

    2002-01-01

    The grant supported research on the structure of the quiet, nonmagnetic chromosphere and on wave excitation and propagation in both the nonmagnetic chromosphere and the magnetic network. The work on the structure of the chromosphere culminated in the recognition that between two competing views of the solar chromosphere, older models by Avrett and collaborators (referred to as VAL) and the newer, dynamical model by Carlsson & Stein (referred to as CS), the clear decision is in favor of the older models, and this in spite of the evident lack of physics, which does not include wave motion and oscillations. The contrast between the static VAL models and the dynamical CS model can be stated most succinctly by comparing the temperature variation implied by the VAL models and the temperature fluctuations of the CS model, which are, respectively, of the order of 10% for the VAL model (at heights where hydrogen is 50% ionized) and a factor of 10 (at the upper boundary of their chromospheric model). The huge fluctuations of the CS model have never been observed, whereas the smaller temperature variations of the VAL models are consistent with ground-based and space-based observations. While it should be obvious which model describes the Sun and which one fails, the case is far from settled in the minds of solar physicists. Thus, much educational work remains to be done and, of course, more research to develop arguments that make the case more convincing. The research on waves and oscillations has been based on a unified theory of excitation of acoustic waves in the field-free atmosphere and of transverse and longitudinal waves in magnetic flux tubes located in the magnetic network by noting, first, that impulsive excitation of all these waves in gravitationally stratified media leads to oscillations at the respective cutoff frequencies and, second, that the observed oscillation frequencies in the nonmagnetic and magnetic parts of the chromosphere match corresponding cutoff

  3. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William J. (Technical Monitor)

    2002-01-01

    The grant supported research on the structure of the quiet, nonmagnetic chromosphere and on wave excitation and propagation in both the nonmagnetic chromosphere and the magnetic network. The work on the structure of the chromosphere culminated in the recognition that between two competing views of the solar chromosphere, older models by Avrett and collaborators (referred to as VAL) and the newer, dynamical model by Carlsson & Stein (referred to as CS), the clear decision is in favor of the older models, and this in spite of the evident lack of physics, which does not include wave motion and oscillations. The contrast between the static VAL models and the dynamical CS model can be stated most succinctly by comparing the temperature variation implied by the VAL models and the temperature fluctuations of the CS model, which are, respectively, of the order of 10% for the VAL model (at heights where hydrogen is 50% ionized) and a factor of 10 (at the upper boundary of their chromospheric model). The huge fluctuations of the CS model have never been observed, whereas the smaller temperature variations of the VAL models are consistent with ground-based and space-based observations. While it should be obvious which model describes the Sun and which one fails, the case is far from settled in the minds of solar physicists. Thus, much educational work remains to be done and, of course, more research to develop arguments that make the case more convincing. The research on waves and oscillations has been based on a unified theory of excitation of acoustic waves in the field-free atmosphere and of transverse and longitudinal waves in magnetic flux tubes located in the magnetic network by noting, first, that impulsive excitation of all these waves in gravitationally stratified media leads to oscillations at the respective cutoff frequencies and, second, that the observed oscillation frequencies in the nonmagnetic and magnetic parts of the chromosphere match corresponding cutoff

  4. Different Responses of Solar Wind and Geomagnetism to Solar Activity during Quiet and Active Periods

    NASA Astrophysics Data System (ADS)

    Kim, Roksoon; Park, J.-Y.; Baek, J.-H.; Kim, B.-G.

    2017-08-01

    It is well known that there are good relations of coronal hole (CH) parameters such as the size, location, and magnetic field strength to the solar wind conditions and the geomagnetic storms. Especially in the minimum phase of solar cycle, CHs in mid- or low-latitude are one of major drivers for geomagnetic storms, since they form corotating interaction regions (CIRs). By adopting the method of Vrsnak et al. (2007), the Space Weather Research Center (SWRC) in Korea Astronomy and Space Science Institute (KASI) has done daily forecast of solar wind speed and Dst index from 2010. Through years of experience, we realize that the geomagnetic storms caused by CHs have different characteristics from those by CMEs. Thus, we statistically analyze the characteristics and causality of the geomagnetic storms by the CHs rather than the CMEs with dataset obtained during the solar activity was very low. For this, we examine the CH properties, solar wind parameters as well as geomagnetic storm indices. As the first result, we show the different trends of the solar wind parameters and geomagnetic indices depending on the degree of solar activity represented by CH (quiet) or sunspot number (SSN) in the active region (active) and then we evaluate our forecasts using CH information and suggest several ideas to improve forecasting capability.

  5. Quiet-time electron increases, a measure of conditions in the outer solar system

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.; Vanhollebeke, M.

    1972-01-01

    One possible explanation for quiet-time electron increases, increases in the intensity of 3-12 MeV interplanetary electrons that have been reported by McDonald, Cline and Simnett, is discussed. It is argued that the electrons in quiet-time increases are galactic in origin, but that the observed increases are not the result of any variation in the modulation of these particles in the inner solar system. It is suggested instead that quiet-time increases may occur when more electrons than normal penetrate a modulating region that lies far beyond the orbit of earth. The number of electrons penetrating this region may increase when field lines that have experienced an unusually large random walk in the photosphere are carried by the solar wind out to the region. As evidence for this increased random walk, it is shown that five solar rotations before most of the quiet-time increases there is an extended period when the amplitude of the diurnal anisotropy, as is measured by the Deep River neutron monitor, is relatively low. Five rotations delay time implies that the proposed modulating region lies at approximately 30 AU from the Sun, assuming that the average solar wind speed is constant over this distance at approximately 400 km/sec.

  6. Models of the quiet and active solar atmosphere from Harvard OSO data.

    NASA Technical Reports Server (NTRS)

    Noyes, R. W.

    1971-01-01

    Review of some Harvard Observatory programs aimed at defining the physical conditions in quiet and active solar regions on the basis of data obtained from the OSO-IV and OSO-VI spacecraft. The spectral range covered is from 300 A to 1400 A. This spectral range consists of emission lines and continua from abundant elements such as hydrogen, helium, carbon, nitrogen, oxygen, silicon, magnesium, aluminum, neon, iron, and calcium in various ionization states ranging from neutral to 15 times ionized. The structure is discussed of the quiet solar atmosphere as deduced from center-to-limb behavior of spectral lines and continua formed in the chromosphere and corona. In reviewing investigations of solar active regions, it is shown that the structure of these regions varies in a complicated manner from point to point. The local structure is influenced by factors such as the magnetic field configuration within the active region and the age or evolutionary state of the region.

  7. QUIET-TIME INTERPLANETARY {approx}2-20 keV SUPERHALO ELECTRONS AT SOLAR MINIMUM

    SciTech Connect

    Wang, Linghua; Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Luhmann, Janet G.; Yoon, Peter H.

    2012-07-01

    We present a statistical survey of {approx}2-20 keV superhalo electrons in the solar wind measured by the SupraThermal Electron instrument on board the two STEREO spacecraft during quiet-time periods from 2007 March through 2009 March at solar minimum. The observed superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f{proportional_to}v{sup -{gamma}}, with {gamma} ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69 {+-} 0.90. The observed power-law spectrum varies significantly on a spatial scale of {approx}>0.1 AU and a temporal scale of {approx}>several days. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from {approx}10{sup -8} cm{sup -3} to 10{sup -6} cm{sup -3}, about 10{sup -9}-10{sup -6} of the solar wind density, and, as well as the power-law spectrum, shows no correlation with solar wind proton density, velocity, or temperature. The density of superhalo electrons appears to show a solar-cycle variation at solar minimum, while the power-law spectral index {gamma} has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity-e.g., active regions, flares or microflares, type III radio bursts, etc.-suggesting that they may be accelerated by processes such as resonant wave-particle interactions in the interplanetary medium, or possibly by nonthermal processes related to the acceleration of the solar wind such as nanoflares, or by acceleration at the CIR forward shocks.

  8. Dependence of Quiet Time Geomagnetic Activity Seasonal Variation on the Solar Magnetic Polarity

    NASA Astrophysics Data System (ADS)

    Oh, Suyeon

    2013-03-01

    The geomagnetic activity shows the semiannual variation stronger in vernal and autumnal equinoxes than in summer and winter solstices. The semiannual variation has been explained by three main hypotheses such as Axial hypothesis, Equinoctial hypothesis, and Russell-McPherron Effect. Many studies using the various geomagnetic indices have done to support three main hypotheses. In recent, Oh & Yi (2011) examined the solar magnetic polarity dependency of the geomagnetic storm occurrence defined by Dst index. They reported that there is no dependency of the semiannual variation on the sign of the solar polar fields. This study examines the solar magnetic polarity dependency of quiet time geomagnetic activity. Using Dxt index (Karinen & Mursula 2005) and Dcx index (Mursula & Karinen 2005) which are recently suggested, in addition to Dst index, we analyze the data of three-year at each solar minimum for eight solar cycles since 1932. As a result, the geomagnetic activity is stronger in the period that the solar magnetic polarity is anti-parallel with the Earth's magnetic polarity. There exists the difference between vernal and autumnal equinoxes regarding the solar magnetic polarity dependency. However, the difference is not statistically significant. Thus, we conclude that there is no solar magnetic polarity dependency of the semiannual variation for quiet time geomagnetic activity.

  9. Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Wang, Linghua; Krucker, Säm; Hannah, Iain

    2016-05-01

    In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of the superhalo could only occur high in the corona (at a heliocentric altitude ≳ 1.9 R_{⊙} (the mean radius of the Sun)), to remain a power-law shape of electron spectrum as observed by Solar Terrestrial Relations Observatory (STEREO) at 1 AU near solar minimum (Wang et al. in Astrophys. J. Lett. 753, L23, 2012). The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, f ˜ ɛ^{-γ} in the photon energy ɛ, with an index γ≈2.0 - 2.3 (3.3 - 3.7) at 10 - 100 keV, for the warm/cold-thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5 % of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) upper limit for quiet-Sun HXRs (Hannah et al. in Astrophys. J. 724, 487, 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limit restricts the number of downward-traveling electrons to at most {≈} 3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population.

  10. Simulation of Quiet-Sun Hard X-rays Related to Solar Wind Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, W.; Wang, L.; Krucker, S.; Hannah, I. G.

    2016-12-01

    Abstract. In this paper, we propose that the accelerated electrons in the quiet-Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of superhalo could only occur high in the corona (at a heliocentric altitude ≥ 1.9 Rs), to remain a power-law shape of electron spectrum as observed by STEREO at 1 AU near solar minimum (Wang et al, 2012).The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, f(ɛ) ∝ ɛ-γ, with an index γ ≈ 2.0-2.3 (3.3-3.7) at 10-100 keV, for the warm/cold thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5% of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the RHESSI upper limits of quiet-Sun HXRs (Hannah et al., 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limits restrict the number of downward-traveling electrons to maximal ≈ 3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population. References: 1. Hannah et al., APJ, 724, 487(2010) 2. Wang et al., APJ Letters,753,L23(2012) 3. Yang et al., RAA,Vol.15,No.3,348-362(2015) 4. Brown J.C., Solar Physics,Vol.18,Issue 3,489,502­­­(1971)

  11. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William (Technical Monitor)

    2003-01-01

    For the meeting of the AAS/SPD in Albuquerque, NM, I organized a Topical Session of the AAS on Structure and Dynamics of Chromospheres. The grant support was used to bring to the US two of the speakers from abroad. I had invited them for presentations at the Session: Dr. Klaus Wilhelm, the former PI of the SUMER instrument on SOHO, from the Max-Planck Institut in Lindau, Germany, and Dr. Sirajul Hasan, from the Indian Institute of Astrophysics in Bangalore, India. Both speakers preceded their trip to the AAS meeting with a stay at the Smithsonian Astrophysical Observatory, where they interacted with members of the Solar and Stellar Physics division. The highlights of the visits were the talks at the AAS/SPD meeting, in which six invited speakers told the audience of astronomers about current problems in solar physics and their relation to stellar problems. An important result of the visits is a paper by Dr. Wilhelm and me on 'Observations of the upper solar chromosphere with SUMER on SOHO', which has been submitted to Astronomy and Astrophysics for publication.

  12. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William (Technical Monitor)

    2003-01-01

    For the meeting of the AAS/SPD in Albuquerque, NM, I organized a Topical Session of the AAS on Structure and Dynamics of Chromospheres. The grant support was used to bring to the US two of the speakers from abroad. I had invited them for presentations at the Session: Dr. Klaus Wilhelm, the former PI of the SUMER instrument on SOHO, from the Max-Planck Institut in Lindau, Germany, and Dr. Sirajul Hasan, from the Indian Institute of Astrophysics in Bangalore, India. Both speakers preceded their trip to the AAS meeting with a stay at the Smithsonian Astrophysical Observatory, where they interacted with members of the Solar and Stellar Physics division. The highlights of the visits were the talks at the AAS/SPD meeting, in which six invited speakers told the audience of astronomers about current problems in solar physics and their relation to stellar problems. An important result of the visits is a paper by Dr. Wilhelm and me on 'Observations of the upper solar chromosphere with SUMER on SOHO', which has been submitted to Astronomy and Astrophysics for publication.

  13. Mode conversion and transmission of waves in quiet solar regions

    NASA Astrophysics Data System (ADS)

    Kontogiannis, Ioannis; Tsiropoula, Georgia; Tziotziou, Konstantinos

    2013-04-01

    We investigate the interaction between acoustic oscillations and the fine-scale structures found at the chromospheric network boundaries that form the magnetic canopy. We use high precision photospheric magnetograms obtained by SOT/SP on-board the Hinode satellite and time series of high spatial resolution filtergrams in five wavelengths along the Hα line profile taken by the Dutch Open Telescope. We extrapolate the photospheric magnetic field using the current-free hypothesis to calculate the vector of the magnetic field and reconstruct the magnetic configuration of the chromosphere. Assuming the VAL-C atmospheric model we are able to estimate the height of formation of the magnetic canopy. We use the wavelet analysis on the Ha observations and obtain the 2-D distribution of the oscillatory power at different atmospheric heights. We then compare the obtained distribution of power with the one predicted by the 2-D model of Schunker & Cally at various magnetic field inclination angles. Our results show that the magnetic shadow and power halo phenomena observed in network regions may be attributed to the conversion/transmission of magneto-acoustic waves on the magnetic canopy. The amount of transmission/conversion depends on the attack angle, i.e. the angle between the wave vector and magnetic field direction. Waves which experience mode conversion and/or transmission can propagate to greater atmospheric heights while some fraction of their energy escapes into the solar wind.

  14. Signature of collision of magnetic flux tubes in the quiet solar photosphere

    NASA Astrophysics Data System (ADS)

    Andic, Aleksandra

    2011-08-01

    Collision of the magnetic flux tubes in the Quiet Sun was proposed as one of the possible sources for the heating of the solar atmosphere (Furusawa and Sakai, 2000). The solar photosphere was observed using the New Solar Telescope ad Big Bear Solar Observatory. In TiO spectral line at 705.68 nm we approached resolution of 0.1''. The horizontal plasma wave was observed spreading from the larger bright point. Shorty after this wave an increase in the oscillatory power appeared at the same location as the observed bright point. This behavior matches some of the results from the simulation of the collision of the two flux tubes with a weak current.

  15. Contributions of Active Regions, Sunspots, Quiet Sun to the Solar UV Spectrum

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; McMullin, D. R.; Cookson, A.; Chapman, G. A.

    2011-12-01

    During the declining phase of the most recent solar cycle, the full disk solar UV spectrum was measured by several space-based instruments, including the SOLSTICE and SIM instruments on the SORCE satellite and the SUSIM instrument on the UARS satellite. These results show distinctively different behavior and have implications for our understanding of the contributions played by various surface features in producing the disk integrated UV spectrum as well as the impact of solar UV emissions on climate. The primary goal of this study is to determine the impact of regions of increased activity (e.g. plage and sunspots) during the recent solar cycle and how this relates to variability of the solar spectrum. Two important results from this study will be the plage and sunspot UV contrast compared to the quiet as well as the center to limb variability of plage, sunspots, and the quiet sun at UV wavelengths. This study will estimate the solar spectrum by utilizing the recently digitized UV spectral radiance observations of plage, sunspots, the quiet sun made by the S082B spectrograph on Skylab, Ca II K images collected at San Fernando Observatory during the recent solar cycle, and a solar spectral model developed under a previous NASA grant. Once generated, these spectra will be compared to the UV observations produced by the above instruments. An important step in the estimation process involves the calibration of the Skylab data for a valid comparison between model and observed spectra. This will require separate calibration curves for SUSIM and SORCE observations. These will be generated from days of no or minimal activity. The determination of separate calibrations will allow any subtle contributions due to variations in instrument performance to be accounted for in the comparison of model and observed spectra. Also, changes in instrumental behavior over time will be separable from real changes in the solar spectrum which are due to contributions of active solar

  16. Contributions of Active Regions, Sunspots, Quiet Sun to the Solar UV Spectrum

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; McMullin, D. R.; Cookson, A.; Chapman, G. A.

    2013-12-01

    During the declining phase of the most recent solar cycle, the full disk solar UV spectrum was measured by several space-based instruments, including the SOLSTICE and SIM instruments on the SORCE satellite and the SUSIM instrument on the UARS satellite. These results show distinctively different behavior and have implications for our understanding of the contributions played by various surface features in producing the disk integrated UV spectrum as well as the impact of solar UV emissions on climate. The primary goal of this study is to determine the impact of regions of increased activity (e.g. plage and sunspots) during the recent solar cycle and how this relates to variability of the solar spectrum. Two important results from this study will be the plage and sunspot UV contrast compared to the quiet as well as the center to limb variability of plage, sunspots, and the quiet sun at UV wavelengths. This study will estimate the solar spectrum by utilizing the recently digitized UV spectral radiance observations of plage, sunspots, the quiet sun made by the S082B spectrograph on Skylab, Ca II K images collected at San Fernando Observatory during the recent solar cycle, and a solar spectral model developed under a previous NASA grant. Once generated, these spectra will be compared to the UV observations produced by the above instruments. An important step in the estimation process involves the calibration of the Skylab data for a valid comparison between model and observed spectra. This will require separate calibration curves for SUSIM and SORCE observations. These will be generated from days of no or minimal activity. The determination of separate calibrations will allow any subtle contributions due to variations in instrument performance to be accounted for in the comparison of model and observed spectra. Also, changes in instrumental behavior over time will be separable from real changes in the solar spectrum which are due to contributions of active solar

  17. STUDY OF CALIBRATION OF SOLAR RADIO SPECTROMETERS AND THE QUIET-SUN RADIO EMISSION

    SciTech Connect

    Tan, Chengming; Yan, Yihua; Tan, Baolin; Fu, Qijun; Liu, Yuying; Xu, Guirong

    2015-07-20

    This work presents a systematic investigation of the influence of weather conditions on the calibration errors by using Gaussian fitness, least chi-square linear fitness, and wavelet transform to analyze the calibration coefficients from observations of the Chinese Solar Broadband Radio Spectrometers (at frequency bands of 1.0–2.0 GHz, 2.6–3.8 GHz, and 5.2–7.6 GHz) during 1997–2007. We found that calibration coefficients are influenced by the local air temperature. Considering the temperature correction, the calibration error will reduce by about 10%–20% at 2800 MHz. Based on the above investigation and the calibration corrections, we further study the radio emission of the quiet Sun by using an appropriate hybrid model of the quiet-Sun atmosphere. The results indicate that the numerical flux of the hybrid model is much closer to the observation flux than that of other ones.

  18. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    PubMed

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.

  19. Alfvénic waves with sufficient energy to power the quiet solar corona and fast solar wind.

    PubMed

    McIntosh, Scott W; De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo; Boerner, Paul; Goossens, Marcel

    2011-07-27

    Energy is required to heat the outer solar atmosphere to millions of degrees (refs 1, 2) and to accelerate the solar wind to hundreds of kilometres per second (refs 2-6). Alfvén waves (travelling oscillations of ions and magnetic field) have been invoked as a possible mechanism to transport magneto-convective energy upwards along the Sun's magnetic field lines into the corona. Previous observations of Alfvénic waves in the corona revealed amplitudes far too small (0.5 km s(-1)) to supply the energy flux (100-200 W m(-2)) required to drive the fast solar wind or balance the radiative losses of the quiet corona. Here we report observations of the transition region (between the chromosphere and the corona) and of the corona that reveal how Alfvénic motions permeate the dynamic and finely structured outer solar atmosphere. The ubiquitous outward-propagating Alfvénic motions observed have amplitudes of the order of 20 km s(-1) and periods of the order of 100-500 s throughout the quiescent atmosphere (compatible with recent investigations), and are energetic enough to accelerate the fast solar wind and heat the quiet corona.

  20. Magnetic Flux Cancellation as the Origin of Solar Quiet-region Pre-jet Minifilaments

    NASA Astrophysics Data System (ADS)

    Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

    2017-08-01

    We investigate the origin of 10 solar quiet-region pre-jet minifilaments, using EUV images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and magnetograms from the SDO Helioseismic and Magnetic Imager (HMI). We recently found that quiet-region coronal jets are driven by minifilament eruptions, where those eruptions result from flux cancellation at the magnetic neutral line under the minifilament. Here, we study the longer-term origin of the pre-jet minifilaments themselves. We find that they result from flux cancellation between minority-polarity and majority-polarity flux patches. In each of 10 pre-jet regions, we find that opposite-polarity patches of magnetic flux converge and cancel, with a flux reduction of 10%-40% from before to after the minifilament appears. For our 10 events, the minifilaments exist for periods ranging from 1.5 hr to 2 days before erupting to make a jet. Apparently, the flux cancellation builds a highly sheared field that runs above and traces the neutral line, and the cool transition region plasma minifilament forms in this field and is suspended in it. We infer that the convergence of the opposite-polarity patches results in reconnection in the low corona that builds a magnetic arcade enveloping the minifilament in its core, and that the continuing flux cancellation at the neutral line finally destabilizes the minifilament field so that it erupts and drives the production of a coronal jet. Thus, our observations strongly support that quiet-region magnetic flux cancellation results in both the formation of the pre-jet minifilament and its jet-driving eruption.

  1. On an efficient shock wave generation mechanism in the quiet solar transition region

    NASA Astrophysics Data System (ADS)

    Dunin-Barkovskaya, O. V.; Somov, B. V.

    2017-08-01

    Two competing fundamental hypotheses are usually postulated in the solar coronal heating problem: heating by nanoflares and heating by waves. In the latter it is assumed that acoustic and magnetohydrodynamic disturbances whose amplitude grows as they propagate in a medium with a decreasing density come from the convection zone. The shock waves forming in the process heat up the corona. In this paper we draw attention to yet another very efficient shock wave generation process that can be realized under certain conditions typical for quiet regions on the Sun. In the approximation of stationary dissipative hydrodynamics we show that a shock wave can be generated in the quiet solar chromosphere-corona transition region by the fall of plasma from the corona into the chromosphere. This shock wave is directed upward, and its dissipation in the corona returns part of the kinetic energy of the falling plasma to the thermal energy of the corona. We discuss the prospects for developing a quantitative nonstationary model of the phenomenon.

  2. Comparative Analysis of Oscillations of a Solar Quiet Region Using Multi-Wavelength Observations

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2010-07-01

    We analyze the temporal behavior of a solar quiet region using a set of multi-wavelength observations obtained during a coordinated campaign. The observations were acquired by the ground-based Dutch Open Telescope (DOT), the Michelson Doppler Imager (MDI) on-board SOHO and the UV filters of the Transition Region and Coronal Explorer (TRACE). A large range of height in the solar atmosphere, from the deep photosphere to the upper chromosphere is covered by these instruments. We investigate the oscillation properties of the intensities and velocities in distinct regions of the quiet Sun, i.e. internetwork, bright points (NBP) defining the network boundaries and dark mottles forming a well-defined rosette, as observed by the different instruments and in the different heights. The variations of the intensities and velocities are studied with wavelet analysis. The aim of our work is to find similarities and/or differences in the oscillatory phenomena observed in the different examined regions, as well as comprehensive information on the interaction of the oscillations and the magnetic field.

  3. Time-causal decomposition of geomagnetic time series into secular variation, solar quiet, and disturbance signals

    USGS Publications Warehouse

    Rigler, E. Joshua

    2017-04-26

    A theoretical basis and prototype numerical algorithm are provided that decompose regular time series of geomagnetic observations into three components: secular variation; solar quiet, and disturbance. Respectively, these three components correspond roughly to slow changes in the Earth’s internal magnetic field, periodic daily variations caused by quasi-stationary (with respect to the sun) electrical current systems in the Earth’s magnetosphere, and episodic perturbations to the geomagnetic baseline that are typically driven by fluctuations in a solar wind that interacts electromagnetically with the Earth’s magnetosphere. In contrast to similar algorithms applied to geomagnetic data in the past, this one addresses the issue of real time data acquisition directly by applying a time-causal, exponential smoother with “seasonal corrections” to the data as soon as they become available.

  4. SCATTERING POLARIZATION OF THE Ca II IR TRIPLET FOR PROBING THE QUIET SOLAR CHROMOSPHERE

    SciTech Connect

    Manso Sainz, R.; Trujillo Bueno, J. E-mail: jtb@iac.e

    2010-10-20

    The chromosphere of the quiet Sun is a very important stellar atmospheric region whose thermal and magnetic structure we need to decipher in order to unlock new discoveries in solar and stellar physics. To this end, we need to identify and exploit observables sensitive to weak magnetic fields (B {approx}< 100 G) and to the presence of cool and hot gas in the bulk of the solar chromosphere. Here, we report on an investigation of the Hanle effect in two semi-empirical models of the quiet solar atmosphere with different chromospheric thermal structures. Our study reveals that the linear polarization profiles produced by scattering in the Ca II IR triplet have thermal and magnetic sensitivities potentially of great diagnostic value. The linear polarization in the 8498 A line shows a strong sensitivity to inclined magnetic fields with strengths between 0.001 and 10 G, while the emergent linear polarization in the 8542 A and 8662 A lines is mainly sensitive to magnetic fields with strengths between 0.001 and 0.1 G. The reason for this is that the scattering polarization of the 8542 A and 8662 A lines, unlike the 8498 A line, is controlled mainly by the Hanle effect in their (metastable) lower levels. Therefore, in regions with magnetic strengths noticeably larger than 1 G, their Stokes Q and U profiles are sensitive only to the orientation of the magnetic field vector. We also find that for given magnetic field configurations the sign of the Q/I and U/I profiles of the 8542 A and 8662 A lines is the same in both atmospheric models, while the sign of the linear polarization profile of the 8498 A line turns out to be very sensitive to the thermal structure of the lower chromosphere. We suggest that spectropolarimetric observations providing information on the relative scattering polarization amplitudes of the Ca II IR triplet will be very useful to improve our empirical understanding of the thermal and magnetic structure of the quiet chromosphere.

  5. Scattering Polarization of the Ca II IR Triplet for Probing the Quiet Solar Chromosphere

    NASA Astrophysics Data System (ADS)

    Manso Sainz, R.; Trujillo Bueno, J.

    2010-10-01

    The chromosphere of the quiet Sun is a very important stellar atmospheric region whose thermal and magnetic structure we need to decipher in order to unlock new discoveries in solar and stellar physics. To this end, we need to identify and exploit observables sensitive to weak magnetic fields (B <~ 100 G) and to the presence of cool and hot gas in the bulk of the solar chromosphere. Here, we report on an investigation of the Hanle effect in two semi-empirical models of the quiet solar atmosphere with different chromospheric thermal structures. Our study reveals that the linear polarization profiles produced by scattering in the Ca II IR triplet have thermal and magnetic sensitivities potentially of great diagnostic value. The linear polarization in the 8498 Å line shows a strong sensitivity to inclined magnetic fields with strengths between 0.001 and 10 G, while the emergent linear polarization in the 8542 Å and 8662 Å lines is mainly sensitive to magnetic fields with strengths between 0.001 and 0.1 G. The reason for this is that the scattering polarization of the 8542 Å and 8662 Å lines, unlike the 8498 Å line, is controlled mainly by the Hanle effect in their (metastable) lower levels. Therefore, in regions with magnetic strengths noticeably larger than 1 G, their Stokes Q and U profiles are sensitive only to the orientation of the magnetic field vector. We also find that for given magnetic field configurations the sign of the Q/I and U/I profiles of the 8542 Å and 8662 Å lines is the same in both atmospheric models, while the sign of the linear polarization profile of the 8498 Å line turns out to be very sensitive to the thermal structure of the lower chromosphere. We suggest that spectropolarimetric observations providing information on the relative scattering polarization amplitudes of the Ca II IR triplet will be very useful to improve our empirical understanding of the thermal and magnetic structure of the quiet chromosphere.

  6. Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    We report the energy spectra and abundances of ions with atomic number, Z, in the interval Z is greater than or equal to 2 and Z is less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between 1994 November and 1998 April as measured by the large-geometry Low Energy Matrix Telescope (LEMT) telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and "anomalous" cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

  7. Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1998-01-01

    This report concerns the energy spectra and abundances of ions with atomic number, Z, in the interval 2 greater than or equal to Z and Z less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between November 1994 and April 1998 as measured by the large-geometry LEMT telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and 'anomalous' cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

  8. Magnetic Flux Cancelation as the Trigger of Solar Quiet-region Coronal Jets

    NASA Astrophysics Data System (ADS)

    Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.; Chakrapani, Prithi

    2016-11-01

    We report observations of 10 random on-disk solar quiet-region coronal jets found in high-resolution extreme ultraviolet (EUV) images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly and having good coverage in magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). Recent studies show that coronal jets are driven by the eruption of a small-scale filament (called a minifilament). However, the trigger of these eruptions is still unknown. In the present study, we address the question: what leads to the jet-driving minifilament eruptions? The EUV observations show that there is a cool-transition-region-plasma minifilament present prior to each jet event and the minifilament eruption drives the jet. By examining pre-jet evolutionary changes in the line of sight photospheric magnetic field, we observe that each pre-jet minifilament resides over the neutral line between majority-polarity and minority-polarity patches of magnetic flux. In each of the 10 cases, the opposite-polarity patches approach and merge with each other (flux reduction between 21% and 57%). After several hours, continuous flux cancelation at the neutral line apparently destabilizes the field holding the cool-plasma minifilament to erupt and undergo internal reconnection, and external reconnection with the surrounding coronal field. The external reconnection opens the minifilament field allowing the minifilament material to escape outward, forming part of the jet spire. Thus, we found that each of the 10 jets resulted from eruption of a minifilament following flux cancelation at the neutral line under the minifilament. These observations establish that magnetic flux cancelation is usually the trigger of quiet-region coronal jet eruptions.

  9. Ubiquitous Horizontal Magnetic Fields in the Quiet Solar Photosphere as Revealed by HINODE Meaurements

    NASA Astrophysics Data System (ADS)

    Lites, Bruce W.; Socas Navarro, H.; Berger, T.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Kubo, M.; Shimizu, T.; Nagata, S.; Hinode Team

    2007-05-01

    Measurements with the HINODE Spectro-Polarimeter (SP) of the quiet Sun allow characterization of the weak, mixed-polarity magnetic flux at the highest angular resolution to date (0.3"), and with good polarimetric sensitivity(0.025% relative to the continuum). The image stabilization of the HINODE spacecraft allows long integrations with degradation of the image quality only by the evolution of the solar granulation. From the Stokes V profile measurements we find an average solar "Apparent Flux Density" of 14 Mx cm-2, with significant Stokes V signals at every position on the disk at all times. However, there are patches of meso-granular size (5-15") where the flux is very weak. At this high sensitivity, transverse fields produce measurable Stokes Q,U linear polarization signals over a majority of the area, with apparent transverse flux densities in the internetwork significantly larger than the corresponding longitudinal flux densities. When viewed at the center of the solar disk, the Stokes V signals (longitudinal fields) show a preference for occurrence in the intergranular lanes, and the Q,U signals occur preferably over the granule interiors, but neither association is exclusive. Hinode is an international project supported by JAXA, NASA, PPARC and ESA. We are grateful to the Hinode team for all their efforts in the design, build and operation of the mission.

  10. Markov Properties of the Magnetic Field in the Quiet Solar Photosphere

    NASA Astrophysics Data System (ADS)

    Gorobets, A. Y.; Borrero, J. M.; Berdyugina, S.

    2016-07-01

    The observed magnetic field on the solar surface is characterized by a very complex spatial and temporal behavior. Although feature-tracking algorithms have allowed us to deepen our understanding of this behavior, subjectivity plays an important role in the identification and tracking of such features. In this paper, we study the temporal stochasticity of the magnetic field on the solar surface without relying on either the concept of magnetic feature or on the subjective assumptions about their identification and interaction. The analysis is applied to observations of the magnetic field of the quiet solar photosphere carried out with the Imaging Magnetograph eXperiment (IMaX) instrument on board the stratospheric balloon, Sunrise. We show that the joint probability distribution functions of the longitudinal ({B}\\parallel ) and transverse ({B}\\perp ) components of the magnetic field, as well as of the magnetic pressure ({B}2={B}\\perp 2+{B}\\parallel 2), verify the necessary and sufficient condition for the Markov chains. Therefore, we establish that the magnetic field as seen by IMaX with a resolution of 0.″15-0.″18 and 33 s cadence, which can be considered as a memoryless temporal fluctuating quantity.

  11. DETECTION OF SMALL-SCALE GRANULAR STRUCTURES IN THE QUIET SUN WITH THE NEW SOLAR TELESCOPE

    SciTech Connect

    Abramenko, V. I.; Yurchyshyn, V. B.; Goode, P. R.; Kitiashvili, I. N.; Kosovichev, A. G.

    2012-09-10

    Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet-Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope at Big Bear Solar Observatory and with a broadband filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0.''0375) augmented by the very high image contrast (15.5% {+-} 0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties, and role of the population of mini-granular structures in the solar magnetoconvection are yet to be explored.

  12. Aircraft Crew Radiation Exposure in Aviation Altitudes During Quiet and Solar Storm Periods

    NASA Astrophysics Data System (ADS)

    Beck, Peter

    The European Commission Directorate General Transport and Energy published in 2004 a summary report of research on aircrew dosimetry carried out by the EURADOS working group WG5 (European Radiation Dosimetry Group, http://www.eurados.org/). The aim of the EURADOS working group WG5 was to bring together, in particular from European research groups, the available, preferably published, experimental data and results of calculations, together with detailed descriptions of the methods of measurement and calculation. The purpose is to provide a dataset for all European Union Member States for the assessment of individual doses and/or to assess the validity of different approaches, and to provide an input to technical recommendations by the experts and the European Commission. Furthermore EURADOS (European Radiation Dosimetry Group, http://www.eurados.org/) started to coordinate research activities in model improvements for dose assessment of solar particle events. Preliminary results related to the European research project CONRAD (Coordinated Network for Radiation Dosimetry) on complex mixed radiation fields at workplaces are presented. The major aim of this work is the validation of models for dose assessment of solar particle events, using data from neutron ground level monitors, in-flight measurement results obtained during a solar particle event and proton satellite data. The radiation protection quantity of interest is effective dose, E (ISO), but the comparison of measurement results obtained by different methods or groups, and comparison of measurement results and the results of calculations, is done in terms of the operational quantity ambient dose equivalent, H* (10). This paper gives an overview of aircrew radiation exposure measurements during quiet and solar storm conditions and focuses on dose results using the EURADOS In-Flight Radiation Data Base and published data on solar particle events

  13. Seasonal and solar activity dependence of the ionospheric electric fields estimated with geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.; Otsuka, Y.

    2016-12-01

    In order to investigate the seasonal and solar activity dependence of the ionospheric electric field estimated with the geomagnetic solar quiet (Sq) daily variation from 1958 to 2015, we analyzed 1-hour geomagnetic field data obtained from 83 geomagnetic observatories from the middle-latitude to equatorial regions with an aid of the IUGONET data analysis tool. These geomagnetic field data were provided by WDC for Geomagnetism, Kyoto University. In this analysis, we first selected geomagnetic field data corresponding to a period of the solar quiet day when the Kp index is less than 4 throughout a day. Next, we identified the Sq variation as a deviation from the value at midnight in both the X and Y components of the geomagnetic field data. Finally, we obtained the monthly-mean ionospheric electric fields by solving Ohm's equation with the two-dimensional height-integrated ionospheric conductivity and geomagnetic Sq variation. As a result, the ionospheric zonal and meridional electric fields shows a clear seasonal variation and 11-year solar activity dependence for all of the investigated geomagnetic stations. The power spectra of the zonal electric field shows three dominant peaks at 6, 12 and 132 months. Moreover, the 4-month periodic component was also found in the middle-latitude regions. The intensity of the zonal electric field is positively correlated with the F10.7 index near the equatorial region (|θ| < 20 degrees, θ: magnetic latitude) with no time lag while it is negatively correlated in the middle-latitude region (|θ| > 20 degrees). The latitudinal difference of the correlation coefficient between the F10.7 index and the zonal electric field intensity is seen over the entire range of geographic longitude analyzed in this study. As a cause of the negative correlation in the middle latitudes, it can be thought that the neutral wind originating from solar tidal waves in the lower thermosphere becomes weaker during a high solar activity due to the

  14. Spatial variability of solar quiet fields along 96° magnetic meridian in Africa: Results from MAGDAS

    NASA Astrophysics Data System (ADS)

    Bolaji, O. S.; Rabiu, A. B.; Bello, O. R.; Yoshikawa, A.; Yumoto, K.; Odeyemi, O. O.; Ogunmodimu, O.

    2015-05-01

    We have used chains of Magnetic Data Acquisition System (MAGDAS) magnetometer records of the horizontal (H) and vertical (Z) magnetic field intensities during September 2008 to August 2009 (year of deep minimum) across Africa to study their variability during the quietest international days, which coincidently associated with the sudden stratospheric warming (SSW) event in January 2009. This selection of the most international quiet days is indicative of 80% that are strongly associated with days when unusually strong and prolonged sudden SSW event occurs in January 2009. Interestingly, in January, a significant magnitude depletion of solar quiet (Sq) equivalent current was observed near noon hours around the magnetic equator (Addis Ababa, ABB) compared to any other months along with a consistent significantly reduced value across the Northern Hemisphere and moderate decrease at the Southern Hemisphere. Also, we found that Nairobi and Dar es Salaam at the Southern Hemisphere, which are close to ABB (dip equator), are strongly prone to westward electric field compared to the magnetic equator and Khartoum at the Northern Hemisphere. Significant negative values of MSq(Z) magnitudes observed near noon hours at Hermanus indicate the presence of induced currents that suggest ocean effects along with reversal to significant positive values in the afternoon, which subsided before 1800 LT in almost all the months, indicate stronger influence of ionospheric currents. On seasonal variability of Sq(H), a slight depression at ABB during September equinox is one of the evidences of seasonal Sq focus shift. Latitudinal variability of Sq near-noon hours was also investigated.

  15. Characterizing the Quiet Solar Photosphere Using a Zeeman-Tomography Approach

    NASA Astrophysics Data System (ADS)

    Carroll, T. A.; Kopf, M.

    2008-09-01

    Based on a novel 3-D Stokes profile inversion (Zeeman-Tomography), which utilizes high-spatial, mixed-polarity magnetoconvection simulation data, we have investigated a number of quiet regions in the solar photosphere observed by Hinode/SOT. Zeeman-Tomography is a unique technique to reconstruct, on a geometric height scale, the 3-dimensional structure of various atmospheric quantities from observed Stokes profiles. Using spectropolarimetric observations from Hinode/SOT our Zeeman-Tomography approach allowed us to determine the spatial structure of the temperature, line-of-sight (LOS) velocity as well as the LOS and horizontal component of the magnetic field, for a photospheric layer of 500 km in height and a field-of-view of 12.000x12.000 km. From the 3-D representation of the photospheric region many small scale flux tube like structures can be identified in the lower photosphere with a maximum field strength of several hundred Gauss. The majority of these structures rapidly lose their strength and coherence with height and only a few stronger flux structures can retain a significant field strength to the upper photosphere. Moreover, we are able to estimate the height dependent probability density function (pdf) of the magnetic field strength. The pdf exhibit a rapid decline of the strong field part of the distribution with height which goes along with a decline in the overall (LOS) magnetic flux density. After a brief introduction of our Zeeman-Tomography approach, I will discuss how these topological and empirically derived findings fit into the current picture of the quiet Sun magnetism.

  16. On the Solar Quiet Variation Measured in Latin America by the Embrace Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Denardini, Clezio Marcos; Moro, Juliano; Araujo Resende, Laysa Cristina; Chen, Sony Su

    2016-07-01

    The present work show the first results of the study about the seasonal variation of the Solar quiet (Sq) Earth's magnetic field based on magnetic measurements from the Embrace Magnetic Network (MagNet) at several latitudes in South America, covering the equatorial and low latitudinal region. For this study, we used data covering the period from September 2010 to December 2015, during the ascending phase of the solar cycle 24. Before analyzing the magnetic data collected from the Embrace Magnet, we compared the magnetic data collected by the Embrace variometer installed at Vassouras-RJ, in Brazil, with the same data collected by the absolute magnetometer installed by the Intermagnet at the same observatory. We show that our data is in pretty good agreement to the absolute values. With respect to the seasonal variation, we show clear seasonal modulation in all components, irrespective the latitude. The H component analysis revealed to have a seasonal dependence in both aspects: the duration of positive excursion along the day and the maximum amplitude. And the other components have also shown remarkable regional characteristic of the variation of the Sq. Finally, we take these results as the first steps towards developing a Sq model to be superimposed to International Geomagnetic Reference Field (IGRF) model as a useful tool for space weather forecast.

  17. Physical properties of the quiet solar chromosphere-corona transition region

    NASA Astrophysics Data System (ADS)

    Dunin-Barkovskaya, O. V.; Somov, B. V.

    2016-12-01

    The physical properties of the quiet solar chromosphere-corona transition region are studied. Here the structure of the solar atmosphere is governed by the interaction of magnetic fields above the photosphere. Magnetic fields are concentrated into thin tubes inside which the field strength is great. We have studied how the plasma temperature, density, and velocity distributions change along a magnetic tube with one end in the chromosphere and the other one in the corona, depend on the plasma velocity at the chromospheric boundary of the transition region. Two limiting cases are considered: horizontally and vertically oriented magnetic tubes. For various plasma densities we have determined the ranges of plasma velocities at the chromospheric boundary of the transition region for which no shock waves arise in the transition region. The downward plasma flows at the base of the transition region are shown to be most favorable for the excitation of shock waves in it. For all the considered variants of the transition region we show that the thermal energy transfer along magnetic tubes can be well described in the approximation of classical collisional electron heat conduction up to very high velocities at its base. The calculated extreme ultraviolet (EUV) emission agrees well with the present-day space observations of the Sun.

  18. Radar observations of magnetospheric activity during extremely quiet solar wind conditions

    NASA Astrophysics Data System (ADS)

    Walker, A. D. M.; Baker, K. B.; Pinnock, M.; Dudeney, J. R.; Rash, J. P. S.

    2002-04-01

    During a period of extremely quiet solar wind conditions from 8 to 10 March 1997, strong activity was observed by the Southern Hemisphere Auroral Radar Experiment Super Dual Auroral Radar Network radars in the Antarctic premidnight ionosphere. This activity took the form of quasiperiodic flow bursts with ionospheric drift velocities exceeding 2 km s-1. Data from the Satellite Experiments Simultaneous with Antarctic Measurements (SESAME) automated geophysical observatories in Antarctica and Defense Meteorological Satellite Program and Polar satellites are used with the radar data to study the convection flow in the southern polar ionosphere at the time of these flow bursts. The study shows that the bursts occurred with an approximate period of 12 min. Their direction was westward, and they were superimposed on a background westward flow. In the premidnight sector this is interpreted as a flow associated with dipolarization of the magnetotail tail field. There is a band of strong particle precipitation associated with the flow bursts. The location suggests that they occur deep in the magnetotail and cannot be associated with any lobe reconnection. They are at a latitude near the region where a viscously driven convection cell is expected to exist, and their sense is that of the return convection flow in such a cell. The results suggest that there is an internal magnetospheric mechanism for sporadic energy release in the magnetotail that need not be associated with changes in solar wind reconnection on the magnetopause.

  19. Tether-Cutting Energetics of a Solar Quiet Region Prominence Eruption

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2003-01-01

    We study the morphology and energetics of a slowly-evolving quiet region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fe xv EUV 284 A data from the EUV Imaging Telescope (EIT) on SOHO. After rising at approx. 1 km/s for about six hours, the prominence accelerates to a velocity of approx. 10 km/s, leaving behind EUV and soft X-ray loop arcades of a weak flare in its source region. Intensity dimmings occur in the eruption region cospatially in EUV and soft X-rays, indicating that the dimmings result from a depletion of material. Over the first two hours of the prominence s rapid rise, flare-like brightenings occur beneath the rising prominence which may correspond to "tether cutting" magnetic reconnection. These brightenings have heating requirements of up to approx. 10(exp 28)-10(exp 29) ergs, and this is comparable to the mechanical energy required for the rising prominence over the same time period. If the ratio of mechanical energy to heating energy remains constant through the early phase of the eruption, then we infer that coronal signatures for the tether cutting may not be apparent at or shortly after the start of the fast phase in this or similar low-energy eruptions, since the plasma-heating energy levels would not exceed that of the background corona.

  20. Solar wind ∼0.1-1.5 keV electrons at quiet times

    SciTech Connect

    Tao, Jiawei; Wang, Linghua Zong, Qiugang; He, Jiansen; Tu, Chuanyi; Li, Gang; Salem, Chadi S.; Bale, Stuart D.; Wimmer-Schweingruber, Robert F.

    2016-03-25

    We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ∼0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature T{sub eff} and density n{sub 0}. We also integrate the the measurements over ∼0.1-1.5 keV to obtain the average electron energy E{sub avg} of the strahl and halo. We find a strong positive correlation between κ and T{sub eff} for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ∼68% have the halo κ smaller than the strahl κ, while ∼50% have the halo E{sub h} larger than the strahl E{sub s}.

  1. Tether-Cutting Energetics of a Solar Quiet Region Prominence Eruption

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2003-01-01

    We study the morphology and energetics of a slowly-evolving quiet region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fe xv EUV 284 A data from the EUV Imaging Telescope (EIT) on SOHO. After rising at approx. 1 km/s for about six hours, the prominence accelerates to a velocity of approx. 10 km/s, leaving behind EUV and soft X-ray loop arcades of a weak flare in its source region. Intensity dimmings occur in the eruption region cospatially in EUV and soft X-rays, indicating that the dimmings result from a depletion of material. Over the first two hours of the prominence s rapid rise, flare-like brightenings occur beneath the rising prominence which may correspond to "tether cutting" magnetic reconnection. These brightenings have heating requirements of up to approx. 10(exp 28)-10(exp 29) ergs, and this is comparable to the mechanical energy required for the rising prominence over the same time period. If the ratio of mechanical energy to heating energy remains constant through the early phase of the eruption, then we infer that coronal signatures for the tether cutting may not be apparent at or shortly after the start of the fast phase in this or similar low-energy eruptions, since the plasma-heating energy levels would not exceed that of the background corona.

  2. Tether-Cutting Energetics of a Solar Quiet Region Prominence Eruption

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2003-01-01

    We study the morphology and energetics of a slowly evolving quiet-region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fexv EUV 284 Angstrom data from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO). After rising at approximately equal to l kilometer per second for about six hours, the prominence accelerates to a velocity of approximately equal to 10 kilometers per second, leaving behind EUV and soft X-ray loop arcades of a weak flare in its source region. Intensity dimmings occur in the eruption region cospatially in EUV and soft X-rays, indicating that the dimmings result from a depletion of material. Over the first two hours of the prominences rapid rise, flare-like brightenings occur beneath the rising prominence that might correspond to tether-cutting magnetic reconnection. These brightenings have heating requirements of up to approximately 10(exp 28)-10(exp 29) ergs, and this is comparable to the mechanical energy required for the rising prominence over the same time period. If the ratio of mechanical energy to heating energy remains constant through the early phase of the eruption, then we infer that coronal signatures for the tether cutting may not be apparent at or shortly after the start of the fast phase in this or similar low-energy eruptions, since the plasma-heating energy levels would not exceed that of the background corona.

  3. Tether-Cutting Energetics of a Solar Quiet Region Prominence Eruption

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2003-01-01

    We study the morphology and energetics of a slowly evolving quiet-region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fexv EUV 284 Angstrom data from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO). After rising at approximately equal to l kilometer per second for about six hours, the prominence accelerates to a velocity of approximately equal to 10 kilometers per second, leaving behind EUV and soft X-ray loop arcades of a weak flare in its source region. Intensity dimmings occur in the eruption region cospatially in EUV and soft X-rays, indicating that the dimmings result from a depletion of material. Over the first two hours of the prominences rapid rise, flare-like brightenings occur beneath the rising prominence that might correspond to tether-cutting magnetic reconnection. These brightenings have heating requirements of up to approximately 10(exp 28)-10(exp 29) ergs, and this is comparable to the mechanical energy required for the rising prominence over the same time period. If the ratio of mechanical energy to heating energy remains constant through the early phase of the eruption, then we infer that coronal signatures for the tether cutting may not be apparent at or shortly after the start of the fast phase in this or similar low-energy eruptions, since the plasma-heating energy levels would not exceed that of the background corona.

  4. Small Scale Dynamo Magnetism And the Heating of the Quiet Sun Solar Atmosphere.

    NASA Astrophysics Data System (ADS)

    Amari, T.

    2015-12-01

    The longstanding problem of the solar atmosphere heating has been addressed by many theoretical studies. Two specific mechanisms have been shown to play a key role in those : magnetic reconnection and waves. On the other hand the necessity of treating together chromosphere and corona has also been been stressed, with debates going on about the possibility of heating coronal plasma by energetic phenomena observed in the chromosphere,based on many key observations such as spicules, tornadoes…. We present some recent results about the modeling of quiet Sun heating in which magnetic fields are generated by a subphotospheric fluid dynamo which is connected to granulation. The model shows a topologically complex magnetic field of 160 G on the Sun's surface, agreeing with inferences obtained from spectropolarimetric observations.Those generated magnetic fields emerge into the chromosphere, providing the required energy flux and then small-scale eruptions releasing magnetic energy and driving sonic motions. Some of the more energetic eruptions can affect the very low corona only.It is also found that taking into account a vertical weak network magnetic field then allows to provide energy higher in the corona, while leaving unchanged the physics of chromospheric eruptions. The coronal heating mechanism rests on the eventual dissipation of Alfven waves generated inside the chromosphere and carrying upwards an adequate energy flux, while more energetic phenomena contribute only weakly to the heating of the corona.

  5. ON QUIET-TIME SOLAR WIND ELECTRON DISTRIBUTIONS IN DYNAMICAL EQUILIBRIUM WITH LANGMUIR TURBULENCE

    SciTech Connect

    Zaheer, S.; Yoon, P. H.

    2013-10-01

    A recent series of papers put forth a self-consistent theory of an asymptotically steady-state electron distribution function and Langmuir turbulence intensity. The theory was developed in terms of the κ distribution which features Maxwellian low-energy electrons and a non-Maxwellian energetic power-law tail component. The present paper discusses a generalized κ distribution that features a Davydov-Druyvesteyn type of core component and an energetic power-law tail component. The physical motivation for such a generalization is so that the model may reflect the influence of low-energy electrons interacting with low-frequency kinetic Alfvénic turbulence as well as with high-frequency Langmuir turbulence. It is shown that such a solution and the accompanying Langmuir wave spectrum rigorously satisfy the balance requirement between the spontaneous and induced emission processes in both the particle and wave kinetic equations, and approximately satisfy the similar balance requirement between the spontaneous and induced scattering processes, which are nonlinear. In spite of the low velocity modification of the electron distribution function, it is shown that the resulting asymptotic velocity power-law index α, where f{sub e} ∼ v {sup –α} is close to the average index observed during the quiet-time solar wind condition, i.e., α ∼ O(6.5) whereas α{sub average} ∼ 6.69, according to observation.

  6. EMERGENCE OF SMALL-SCALE MAGNETIC LOOPS THROUGH THE QUIET SOLAR ATMOSPHERE

    SciTech Connect

    Martinez Gonzalez, M. J.

    2009-08-01

    We investigate the emergence of magnetic flux in the quiet Sun at very small spatial scales, focusing on the magnetic connection between the photosphere and chromosphere. The observational data consist of spectropolarimetric measurements and filtergrams taken with the Hinode satellite and the Dutch Open Telescope. We find that a significant fraction of the magnetic flux present in internetwork regions appears in the form of {omega}-shaped loops. The emergence rate is 0.02 loops per hour and arcsec{sup -2}, which brings 1.1 x 10{sup 12} Mx s{sup -1} arcsec{sup -2} of new flux to the solar surface. Initially, the loops are observed as small patches of linear polarization above a granular cell. Shortly afterward, two footpoints of opposite polarity become visible in circular polarization within or at the edges of the granule and start moving toward the adjacent intergranular space. The orientation of the footpoints does not seem to obey Hale's polarity rules. The loops are continuously buffeted by convective motions, but they always retain a high degree of coherence. Interestingly, 23% of the loops that emerge in the photosphere reach the chromosphere (16 cases out of 69). They are first detected in Fe I 630 nm magnetograms and 5 minutes later in Mg I b 517.3 nm magnetograms. After about 8 minutes, some of them are also observed in Ca II H line-core images, where the footpoints produce small brightness enhancements.

  7. Solar quiet current response in the African sector due to a 2009 sudden stratospheric warming event

    NASA Astrophysics Data System (ADS)

    Bolaji, O. S.; Oyeyemi, E. O.; Owolabi, O. P.; Yamazaki, Y.; Rabiu, A. B.; Okoh, D.; Fujimoto, A.; Amory-Mazaudier, C.; Seemala, G. K.; Yoshikawa, A.; Onanuga, O. K.

    2016-08-01

    We present solar quiet (Sq) variation of the horizontal (H) magnetic field intensity deduced from Magnetic Data Acquisition System (MAGDAS) records over Africa during an unusual strong and prolonged 2009 sudden stratospheric warming (SSW) event. A reduction in the SqH magnitude that enveloped the geomagnetic latitudes between 21.13°N (Fayum FYM) in Egypt and 39.51°S (Durban DRB) in South Africa was observed, while the stratospheric polar temperature was increasing and got strengthened when the stratospheric temperature reached its maximum. Another novel feature associated with the hemispheric reduction is the reversal in the north-south asymmetry of the SqH, which is indicative of higher SqH magnitude in the Northern Hemisphere compared to the Southern Hemisphere during SSW peak phase. The reversal of the equatorial electrojet (EEJ) or the counter electrojet (CEJ) was observed after the polar stratospheric temperature reached its maximum. The effect of additional currents associated with CEJ was observed in the Southern Hemisphere at middle latitude. Similar changes were observed in the EEJ at the South America, Pacific Ocean, and Central Asia sectors. The effect of the SSW is largest in the South American sector and smallest in the Central Asian sector.

  8. Explaining Inverted-temperature Loops in the Quiet Solar Corona with Magnetohydrodynamic Wave-mode Conversion

    NASA Astrophysics Data System (ADS)

    Schiff, Avery J.; Cranmer, Steven R.

    2016-11-01

    Coronal loops trace out bipolar, arch-like magnetic fields above the Sun’s surface. Recent measurements that combine rotational tomography, extreme-ultraviolet imaging, and potential-field extrapolation have shown the existence of large loops with inverted-temperature profiles, i.e., loops for which the apex temperature is a local minimum, not a maximum. These “down loops” appear to exist primarily in equatorial quiet regions near solar minimum. We simulate both these and the more prevalent large-scale “up loops” by modeling coronal heating as a time-steady superposition of (1) dissipation of incompressible Alfvén wave turbulence and (2) dissipation of compressive waves formed by mode conversion from the initial population of Alfvén waves. We found that when a large percentage (>99%) of the Alfvén waves undergo this conversion, heating is greatly concentrated at the footpoints and stable “down loops” are created. In some cases we found loops with three maxima that are also gravitationally stable. Models that agree with the tomographic temperature data exhibit higher gas pressures for “down loops” than for “up loops,” which is consistent with observations. These models also show a narrow range of Alfvén wave amplitudes: 3 to 6 km s-1 at the coronal base. This is low in comparison to typical observed amplitudes of 20-30 km s-1 in bright X-ray loops. However, the large-scale loops we model are believed to compose a weaker diffuse background that fills much of the volume of the corona. By constraining the physics of loops that underlie quiescent streamers, we hope to better understand the formation of the slow solar wind.

  9. Quiet-time properties of low-energy (less than 10 MeV per nucleon) interplanetary ions during solar maximum and solar minimum

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Reames, D. V.; Wenzel, K.-P.; Rodriguez-Pacheco, J.

    1990-01-01

    The abundances and spectra of 1-10 MeV per nucleon protons, He-3, He-4, C, O, and Fe have been exmained during solar quiet periods from 1978 to 1987 in an effort to investigate the recent suggestion by Wenzel et al. (1990) that the ions may be of solar origin. It is found that the intensities of the ions, other than O, fall by an order of magnitude between solar maximum and solar minimum, and that the greater than 1 MeV per nucleon ions exhibit weak streaming away from the sun. More significantly, the quiet-time ions during solar maximum have He-3-rich and Fe-rich abundances which are established characteristics of small impulsive solar flares. Thus, it is suggested that small unresolved impulsive flares make a substantial contribution to the 'quiet-time' fluxes. He-4 from these flares may also contribute strongly to the ion spectra that were reported for the 35-1600 keV energy range by Wenzel et al.

  10. Quiet-time properties of low-energy (less than 10 MeV per nucleon) interplanetary ions during solar maximum and solar minimum

    SciTech Connect

    Richardson, I.G.; Reames, D.V.; Wenzel, K.P.; Rodriguez-Pacheco, J. ESTEC, Noordwijk )

    1990-11-01

    The abundances and spectra of 1-10 MeV per nucleon protons, He-3, He-4, C, O, and Fe have been examined during solar quiet periods from 1978 to 1987 in an effort to investigate the recent suggestion by Wenzel et al. (1990) that the ions may be of solar origin. It is found that the intensities of the ions, other than O, fall by an order of magnitude between solar maximum and solar minimum, and that the greater than 1 MeV per nucleon ions exhibit weak streaming away from the sun. More significantly, the quiet-time ions during solar maximum have He-3-rich and Fe-rich abundances which are established characteristics of small impulsive solar flares. Thus, it is suggested that small unresolved impulsive flares make a substantial contribution to the quiet-time fluxes. He-4 from these flares may also contribute strongly to the ion spectra that were reported for the 35-1600 keV energy range by Wenzel et al. 18 refs.

  11. If the Sun is so quiet, why is the Earth ringing? A comparison of two solar minimum intervals

    NASA Astrophysics Data System (ADS)

    Gibson, S. E.; Kozyra, J. U.; de Toma, G.; Emery, B. A.; Onsager, T. G.; Thompson, B. J.

    2009-12-01

    A system-oriented analysis of new observations from the recent international Whole Heliosphere Interval (WHI) campaign in comparison with the equivalent Whole Sun Month (WSM) campaign from last cycle’s minimum yields new insight into solar quiet intervals and the solar minimum Sun-Earth system. We use a side-by-side comparison of these two intervals to demonstrate that sunspot numbers, while providing a good measure of solar activity, do not provide sufficient information to gauge solar and heliospheric magnetic complexity and its effect at the Earth. The present solar minimum is exceptionally quiet, with sunspot numbers the lowest in 75 years, solar wind density and IMF strength at the lowest values ever observed, and geomagnetic indices and solar EUV fluxes the lowest in three solar cycles. Despite, or perhaps because of this global weakness in the heliospheric magnetic field, large near-equatorial coronal holes lingered even as the sunspots disappeared, indicating significant open magnetic flux at low latitudes. Consequently, for the months surrounding the WHI campaign, strong, long, and recurring high-speed streams in the solar wind intercepted the Earth in contrast to the weaker and more sporadic streams that occurred around the time of the WSM campaign. Since the speed, duration and southward magnetic field component in wind streams determine the severity of space weather effects, the geospace environment responded quite differently to the two solar minimum heliospheric morphologies. We illustrate this point with the behavior of relativistic electrons in the Earth’s outer radiation belt, which were more than three times stronger during WHI than in WSM. The cause is clear: it is well-known that high-speed streams drive radiation belt population, and indeed, for the months surrounding WHI, geospace and upper atmospheric parameters were ringing with the periodicities of the solar wind in a manner that was absent last cycle minimum. Such behavior could not

  12. Formation mechanisms of the midlatitudinal NmF2 semiannual anomaly under daytime quiet geomagnetic conditions at low solar activity

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2017-07-01

    The F-region peak electron densities NmF2 measured during daytime quiet geomagnetic conditions at low solar activity on January 22, 2008, April 8, 1997, July 12, 1986, and October 26, 1995, are compared. Ionospheric parameters are measured by the ionosonde and incoherent scatter radar at Millstone Hill and calculated with the use of a 1D nonstationary ionosphere-plasmasphere model of number densities and temperatures of electrons and ions at middle geomagnetic latitudes. The formation of the semiannual anomaly of the midlatitudinal NmF2 under daytime quiet geomagnetic conditions at low solar activity is studied. The study shows that the semiannual NmF2 anomaly occurs due to the total impact of three main causes: seasonal variations in the velocity of plasma drift along the geomagnetic field due to the corresponding variations in the components of the neutral wind velocity; seasonal variations in the composition and temperature of the neutral atmosphere; and the dependence of the solar zenith angle on a number of the day in the year at the same solar local time.

  13. Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

    NASA Technical Reports Server (NTRS)

    Moon, S.; Simnett, G. M.; White, R. S.

    1975-01-01

    The UCR large area solid-angle double scatter neutron telescope was flown to search for solar neutrons on 3 balloon flights on September 26, 1971, May 14, 1972 and September 19, 1972. The first two flights were launched from Palestine, Texas and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet time solar neutron fluxes at the 95% confidence level are .00028, .00046, .00096 and .00090 neutrons/sq cm-sec in the energy intervals of 10-30, 30-50, 50-100 and 10-100 MeV, respectively.

  14. Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

    NASA Technical Reports Server (NTRS)

    Moon, S.; Simnett, G. M.; White, R. S.

    1976-01-01

    A large-area solid-angle double-scatter neutron telescope was flown to search for solar neutrons on three balloon flights in 1971 and 1972. The first two flights were launched from Palestine, Texas, and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet-time solar neutron fluxes at the 95-per cent confidence level are 2.8, 4.6, 9.6, and 9.0 x 10 to the -4th power neutron/sq cm/sec in the energy intervals of 10-30, 30-50, 50-100, and 10-100 MeV, respectively.

  15. Pole-equator difference and the variability of the brightness of the chromospheric CaII-K-network elements in quiet regions over the solar cycle

    NASA Technical Reports Server (NTRS)

    Kariyappa, R.

    1995-01-01

    The dependence of the brightness of chromospheric network elements on latitude was investigated for quiet solar regions. Calibrated photographic CaII K-spectroheliograms were used to compare the variation in brightness at the center of the disk with higher latitude of chromospheric network elements in a quiet region as a function of solar activity. It was found that there was no significant difference in brightness between the center of the solar disk and higher latitude. It is concluded that the brightness of the chromospheric network elements in a quiet region does not depend on the latitude, but that the variation in the intensity enhancement is related to the level of solar activity.

  16. Correlation lifetimes of quiet and magnetic granulation from the SOUP instrument on Spacelab 2. [Solar Optical Universal Polarimeter

    NASA Technical Reports Server (NTRS)

    Title, A.; Tarbell, T.; Topka, K.; Acton, L.; Duncan, D.

    1988-01-01

    The time sequences of diffraction limited granulation images obtained by the Solar Optical Universal Polarimeter on Spacelab 2 are presented. The uncorrection autocorrelation limetime in magnetic regions is dominated by the 5-min oscillation. The removal of this oscillation causes the autocorrelation lifetime to increase by more than a factor of 2. The results suggest that a significant fraction of granule lifetimes are terminated by nearby explosions. Horizontal displacements and transverse velocities in the intensity field are measured. Lower limits to the lifetime in the quiet and magnetic sun are set at 440 s and 950 s, respectively.

  17. The Angular Distribution of Quiet-time ~20-300 keV Superhalo Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Yang, L.; Wang, L.; He, J.; Tu, C. Y.; Pei, Z.

    2014-12-01

    The angular distribution of solar wind superhalo electrons carries important information on the electron acceleration location and scattering in the interplanetary medium. Here we present a comprehensive study of the angular distribution of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. For quiet-time intervals, we re-bin the observed electron pitch angle distributions into the outward-traveling and inward-traveling bins, according the direction of interplanetary magnetic field (IMF). The inward-outward anisotropy of superhalo electrons at energy E is defined as A = 2(fout - fin)/(fout + fin), where fout (fin) is the average flux of outward-traveling (inward-traveling) electrons. We find that among all the ~640 quiet-time intervals, ~5% have an A > 0.1 (referred to as "outward events"), ~5% have an A < -0.1 (referred to as "inward events"), and ~90% have an |A| ≤ 0.1 (referred to as "isotropic events"). Isotropic events show no clear correlation with solar wind parameters (nSW, Vsw and Tp), IMF and solar wind turbulence spectrum. Inward and outward events also have no association with the IMF and nSW. But the occurrence ratio of outward (inward) events over all the events, α, roughly decreases (increases) with increasing VSW. Moreover, for outward (inward) events, α roughly increases with ρe/ρTp, where ρTp is the solar wind thermal proton gyroradius that is related to the separation between the turbulence inertial and dissipation ranges. These results suggest that quite-time superhalo electrons are generally isotropic due to the wave-particle interaction in the interplanetary medium; outward-traveling (inward-traveling) superhalo electrons may come from the acceleration occurring beyond (within) 1 AU, probably by CIRs or turbulence. We will also present a case study of several quiet-time electron events with the anisotropy A increasing with the electron energy E.

  18. Nonlinear Torsional and Compressional Waves in a Magnetic Flux Tube with Electric Current near the Quiet Solar Photospheric Network

    NASA Astrophysics Data System (ADS)

    Sakai, J. I.; Minamizuka, R.; Kawata, T.; Cramer, N. F.

    2001-04-01

    Recent high-resolution observations from photospheric magnetograms made with the SOHO/Michelson Doppler Imager instrument and the Swedish Vacuum Solar Telescope on La Palma showed that magnetic flux tubes in the quiet photospheric network of the solar photosphere are highly dynamic objects with small-scale substructures. We investigate nonlinear waves propagating along a magnetic flux tube in weakly ionized plasmas with high plasma beta (β~=1) by using three-dimensional neutral MHD equations. Recently Sakai et al. investigated nonlinear wave propagation along a magnetic flux tube with a weak current for the two cases of uniform density along the flux tube and density inhomogeneity due to solar gravity. They showed that shear Alfvén waves are excited by localized, predominantly rotational perturbations and that excited waves with a strong upflow of wave energy can propagate only upward along the flux tube when density inhomogeneity due to gravity is taken into account. In this paper we extend this work by investigating nonlinear torsional and compressional waves in a magnetic flux tube with a strong electric current, i.e., a twisted magnetic field, near the quiet solar photospheric network. If gravity is neglected, the torsional waves are found to propagate in a direction such as to decrease the twist of the magnetic field, while the compressional waves propagate symmetrically. We have found that solar gravity results in the important effect that wave energies excited by both torsional and compressional disturbances can be transferred upward in both untwisted and highly twisted flux tubes and eventually contribute to coronal heating.

  19. QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

    SciTech Connect

    Tao, Jiawei; Wang, Linghua; Zong, Qiugang; He, Jiansen; Tu, Chuanyi; Li, Gang; Salem, Chadi S.; Bale, Stuart D.; Wimmer-Schweingruber, Robert F.

    2016-03-20

    We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl and halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)

  20. Anomaly in the quiet-time helium spectrum at 1 MeV per nucleon. [IMP measured solar spectra

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Hovestadt, D.; Kleckler, B.; Vollmer, O.; Fan, C. Y.

    1976-01-01

    The IMP-8 satellite observed (in 1974-1975) an unexpected hump in the solar helium spectrum between 0.6 and about 3 MeV per nucleon and an enhanced helium abundance of up to 70 MeV per nucleon. The energy spectrum of helium below 0.6 MeV per nucleon was consistent with the proton spectrum below 1.5 MeV, while the proton-to-alpha ratio was about 30. The origin of this anomalous low-energy, quiet-time helium is as yet undecided. The alpha particles could be of solar origin, could have been accelerated in the heliosphere or could be of galactic origin.

  1. Long-term variation in the ionosphere and lower thermosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Hori, T.; Nose, M.; Otsuka, Y.

    2015-12-01

    In order to investigate characteristics of the long-term variation in the ionosphere and lower thermosphere, we analyzed the amplitude of geomagnetic solar quiet (Sq) field daily variation using 1-h geomagnetic field data obtained from 69 geomagnetic stations within the period of 1947-2013. In the present data analysis, we took advantage of the Inter-university Upper atmosphere Global Observation NETwork (IUGONET) products (metadata database and analysis software) for finding and handling the long-term observation data obtained at many observatories. The Sq amplitude observed at these geomagnetic stations showed a clear solar activity dependence and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008-2009. This significant depression implies that the solar extreme ultraviolet (EUV) radiation responsible for ionization of the upper atmosphere decreased during this solar cycle minimum. In order to examine a global distribution of the long-term trend in the Sq amplitude, we derived the residual Sq amplitude from the deviation from the fitting curve between the solar F10.7 index and Sq amplitude. As a result, a majority of the trends in the residual Sq amplitude showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. Moreover, we estimate the neutral wind in the lower thermosphere from the Sq amplitude and height-integrated ionospheric conductivity in order to know the physical mechanism of the long-term trend in the residual Sq amplitude. As a result, the estimated thermospheric zonal and meridional winds showed a seasonal variation with a period of one year or less, but the solar activity dependence was unclear. This result suggests that the solar cycle dependence of the Sq amplitude may be mainly attributed to the variation of the ionospheric conductivity.

  2. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, Atsuki; Koyama, Yukinobu; Nose, Masahito; Hori, Tomoaki; Otsuka, Yuichi; Yatagai, Akiyo

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet (Sq) geomagnetic field daily variation have been investigated using 1-h geomagnetic field data obtained from 69 geomagnetic observation stations within the period of 1947 to 2013. The Sq amplitude observed at these geomagnetic stations showed a clear dependence on the 10- to 12-year solar activity cycle and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008 to 2009. The relationship between the solar F10.7 index and Sq amplitude was approximately linear but about 53% of geomagnetic stations showed a weak nonlinear relation to the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second-order fitting curve between the solar F10.7 index and Sq amplitude during 1947 to 2013 and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, the majority of trends in the residual Sq amplitude that passed through a trend test showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity at 100-km altitude and residual Sq amplitude showed an anti-correlation for about 71% of the geomagnetic stations. Furthermore, the residual Sq amplitude at the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  3. Quiet-Time Suprathermal (˜0.1 - 200 keV) Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Wang, Linghua; Yang, Liu; Tao, Jiawei; Zong, Qiugang; Li, Gang; Wimmer-Schweingruber, Robert; He, Jiansen; Tu, Chuanyi; Bale, Stuart

    2017-04-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-200 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. The observed energy spectrum of both (beaming) strahl and (isotropic) halo electrons at ˜0.1-1.5 keV generally fits to a Kappa distribution function with an index κ and effective temperature Teff, while the observed energy spectrum of nearly isotropic superhalo electrons at ˜20-200 keV generally fits to a power-law function, J ˜ E-β. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl density and halo density. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. For the superhalo population, the spectral index β ranges from ˜1.6 to ˜3.7 and the integrated density nsup ranges from 10-8 cm-3 to 10-5 cm-3, with no clear association with the sunspot number. In solar cycle 23 (24), the distribution of β has a broad maximum between 2.4 and 2.8 (2.0 and 2.4). All the strahl, halo and superhalo populations show no obvious correlation with the solar wind core population. These results reflect the nature of the generation of solar wind suprathermal electrons.

  4. Comparison of physical properties of quiet and active regions through the analysis of magnetohydrodynamic simulations of the solar photosphere

    SciTech Connect

    Criscuoli, S.

    2013-11-20

    Recent observations have shown that the photometric and dynamic properties of granulation and small-scale magnetic features depend on the amount of magnetic flux of the region they are embedded in. We analyze results from numerical hydrodynamic and magnetohydrodynamic simulations characterized by different amounts of average magnetic flux and find qualitatively the same differences as those reported from observations. We show that these different physical properties result from the inhibition of convection induced by the presence of the magnetic field, which changes the temperature stratification of both quiet and magnetic regions. Our results are relevant for solar irradiance variations studies, as such differences are still not properly taken into account in irradiance reconstruction models.

  5. Comparison of Physical Properties of Quiet and Active Regions Through the Analysis of Magnetohydrodynamic Simulations of the Solar Photosphere

    NASA Astrophysics Data System (ADS)

    Criscuoli, S.

    2013-11-01

    Recent observations have shown that the photometric and dynamic properties of granulation and small-scale magnetic features depend on the amount of magnetic flux of the region they are embedded in. We analyze results from numerical hydrodynamic and magnetohydrodynamic simulations characterized by different amounts of average magnetic flux and find qualitatively the same differences as those reported from observations. We show that these different physical properties result from the inhibition of convection induced by the presence of the magnetic field, which changes the temperature stratification of both quiet and magnetic regions. Our results are relevant for solar irradiance variations studies, as such differences are still not properly taken into account in irradiance reconstruction models.

  6. How Quiet is the Quiet Magnetosphere?

    NASA Astrophysics Data System (ADS)

    Hesse, M.; Moretto, T.; Friis-Christensen, E. A.; Opgenoorth, H. J.

    2015-12-01

    The term "quiet magnetosphere" has been accepted as a descriptor of a magnetospheric state under small solar wind driving conditions. Observations indicate that such a state entails a substantial reduction of field-aligned currents, the polar cap potential, polar cap size, and general convection in the magnetosphere. While this paradigm is often discussed, little research has been applied to determine the detailed state of the structure of the magnetosphere. Due to basic constraints, such as entropy conservation, it appears, for example, very likely that the state of the quiet magnetosphere depends on the dynamic history. Relaxation to a unique relaxed state, should, if at all, only be possible on some yet undetermined relaxation time scale. Finally, the quiet state should depend on residual fluctuations in the solar wind driver, even if the IMF is northward. This presentation is shedding some first light on the issue of the quiet magnetosphere. We are using global MHD simulations to study the relaxation process starting from different driven states. By studying different key parameters, we derive estimates for relaxation time scales, and we will demonstrate the role solar wind fluctuations play in shaping the typical behavior of a relaxed magnetosphere.

  7. Observations of high-energy jets in the corona above the quiet sun, the heating of the corona, and the acceleration of the solar wind

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.; Bartoe, J.-D. F.

    1983-01-01

    High spatial resolution observations of the ultraviolet solar spectrum which reveal high-energy events in the quiet sun are presented. The tandem Wadsworth spectrograph used to make the observations is described along with the observing techniques, and a brief description of the characteristics of high-resolution transition zone spectra is given. The sizes, velocities, line profiles, time behavior, temperature range, differential emission measures, densities, masses, energies, and birthrates of turbulent events and jets in the quiet sun are derived from the observations and discussed. Possible accelerating mechanisms for these events are discussed, and the consequences of these events for the heating of the solar corona are discussed. A cloud model of the solar wind is proposed and possible correlations between the high-energy events and other solar fine-structure features are discussed.

  8. CORONAL HEATING BY THE INTERACTION BETWEEN EMERGING ACTIVE REGIONS AND THE QUIET SUN OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

    SciTech Connect

    Zhang, Jun; Zhang, Bin; Li, Ting; Yang, Shuhong; Zhang, Yuzong; Li, Leping; Chen, Feng; Peter, Hardi E-mail: liting@nao.cas.cn E-mail: yuzong@nao.cas.cn E-mail: chen@mps.mpg.de

    2015-02-01

    The question of what heats the solar corona remains one of the most important puzzles in solar physics and astrophysics. Here we report Solar Dynamics Observatory Atmospheric Imaging Assembly observations of coronal heating by the interaction between emerging active regions (EARs) and the surrounding quiet Sun (QS). The EARs continuously interact with the surrounding QS, resulting in dark ribbons which appear at the boundary of the EARs and the QS. The dark ribbons visible in extreme-ultraviolet wavelengths propagate away from the EARs with speeds of a few km s{sup −1}. The regions swept by the dark ribbons are brightening afterward, with the mean temperature increasing by one quarter. The observational findings demonstrate that uninterrupted magnetic reconnection between EARs and the QS occurs. When the EARs develop, the reconnection continues. The dark ribbons may be the track of the interface between the reconnected magnetic fields and the undisturbed QS’s fields. The propagating speed of the dark ribbons reflects the reconnection rate and is consistent with our numerical simulation. A long-term coronal heating which occurs in turn from nearby the EARs to far away from the EARs is proposed.

  9. Wave propagation in a solar quiet region and the influence of the magnetic canopy

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2016-01-01

    Aims: We seek indications or evidence of transmission/conversion of magnetoacoustic waves at the magnetic canopy, as a result of its impact on the properties of the wave field of the photosphere and chromosphere. Methods: We use cross-wavelet analysis to measure phase differences between intensity and Doppler signal oscillations in the Hα, Ca ii h, and G-band. We use the height of the magnetic canopy to create appropriate masks to separate internetwork (IN) and magnetic canopy regions. We study wave propagation and differences between these two regions. Results: The magnetic canopy affects wave propagation by lowering the phase differences of progressive waves and allowing the propagation of waves with frequencies lower than the acoustic cut-off. We also find indications in the Doppler signals of Hα of a response to the acoustic waves at the IN, observed in the Ca ii h line. This response is affected by the presence of the magnetic canopy. Conclusions: Phase difference analysis indicates the existence of a complicated wave field in the quiet Sun, which is composed of a mixture of progressive and standing waves. There are clear imprints of mode conversion and transmission due to the interaction between the p-modes and small-scale magnetic fields of the network and internetwork.

  10. The Brightness Temperature of the Quiet Solar Chromosphere at 2.6 mm

    NASA Astrophysics Data System (ADS)

    Iwai, Kazumasa; Shimojo, Masumi; Asayama, Shinichiro; Minamidani, Tetsuhiro; White, Stephen; Bastian, Timothy; Saito, Masao

    2017-01-01

    The absolute brightness temperature of the Sun at millimeter wavelengths is an important diagnostic of the solar chromosphere. Because the Sun is so bright, measurement of this property usually involves the operation of telescopes under extreme conditions and requires a rigorous performance assessment of the telescope. In this study, we establish solar observation and calibration techniques at 2.6 mm wavelength for the Nobeyama 45 m telescope and accurately derive the absolute solar brightness temperature. We tune the superconductor-insulator-superconductor (SIS) receiver by inducing different bias voltages onto the SIS mixer to prevent saturation. Then, we examine the linearity of the receiver system by comparing outputs derived from different tuning conditions. Furthermore, we measure the lunar filled beam efficiency of the telescope using the New Moon, and then derive the absolute brightness temperature of the Sun. The derived solar brightness temperature is 7700 ± 310 K at 115 GHz. The telescope beam pattern is modeled as a summation of three Gaussian functions and derived using the solar limb. The real shape of the Sun is determined via deconvolution of the beam pattern from the observed map. Such well-calibrated single-dish observations are important for high-resolution chromospheric studies because they provide the absolute temperature scale that is lacking from interferometer observations.

  11. PHYSICAL PROPERTIES OF LARGE AND SMALL GRANULES IN SOLAR QUIET REGIONS

    SciTech Connect

    Yu Daren; Xie Zongxia; Hu Qinghua; Yang Shuhong; Zhang Jun; Wang Jingxiu E-mail: zjun@ourstar.bao.ac.cn

    2011-12-10

    The normal mode observations of seven quiet regions obtained by the Hinode spacecraft are analyzed to study the physical properties of granules. An artificial intelligence technique is introduced to automatically find the spatial distribution of granules in feature spaces. In this work, we investigate the dependence of granular continuum intensity, mean Doppler velocity, and magnetic fields on granular diameter. We recognized 71,538 granules by an automatic segmentation technique and then extracted five properties: diameter, continuum intensity, Doppler velocity, and longitudinal and transverse magnetic flux density to describe the granules. To automatically explore the intrinsic structures of the granules in the five-dimensional parameter space, the X-means clustering algorithm and one-rule classifier are introduced to define the rules for classifying the granules. It is found that diameter is a dominating parameter in classifying the granules and two families of granules are derived: small granules with diameters smaller than 1.''44, and large granules with diameters larger than 1.''44. Based on statistical analysis of the detected granules, the following results are derived: (1) the averages of diameter, continuum intensity, and Doppler velocity in the upward direction of large granules are larger than those of small granules; (2) the averages of absolute longitudinal, transverse, and unsigned flux density of large granules are smaller than those of small granules; (3) for small granules, the average of continuum intensity increases with their diameters, while the averages of Doppler velocity, transverse, absolute longitudinal, and unsigned magnetic flux density decrease with their diameters. However, the mean properties of large granules are stable; (4) the intensity distributions of all granules and small granules do not satisfy Gaussian distribution, while that of large granules almost agrees with normal distribution with a peak at 1.04 I{sub 0}.

  12. Physical Properties of Large and Small Granules in Solar Quiet Regions

    NASA Astrophysics Data System (ADS)

    Yu, Daren; Xie, Zongxia; Hu, Qinghua; Yang, Shuhong; Zhang, Jun; Wang, Jingxiu

    2011-12-01

    The normal mode observations of seven quiet regions obtained by the Hinode spacecraft are analyzed to study the physical properties of granules. An artificial intelligence technique is introduced to automatically find the spatial distribution of granules in feature spaces. In this work, we investigate the dependence of granular continuum intensity, mean Doppler velocity, and magnetic fields on granular diameter. We recognized 71,538 granules by an automatic segmentation technique and then extracted five properties: diameter, continuum intensity, Doppler velocity, and longitudinal and transverse magnetic flux density to describe the granules. To automatically explore the intrinsic structures of the granules in the five-dimensional parameter space, the X-means clustering algorithm and one-rule classifier are introduced to define the rules for classifying the granules. It is found that diameter is a dominating parameter in classifying the granules and two families of granules are derived: small granules with diameters smaller than 1farcs44, and large granules with diameters larger than 1farcs44. Based on statistical analysis of the detected granules, the following results are derived: (1) the averages of diameter, continuum intensity, and Doppler velocity in the upward direction of large granules are larger than those of small granules; (2) the averages of absolute longitudinal, transverse, and unsigned flux density of large granules are smaller than those of small granules; (3) for small granules, the average of continuum intensity increases with their diameters, while the averages of Doppler velocity, transverse, absolute longitudinal, and unsigned magnetic flux density decrease with their diameters. However, the mean properties of large granules are stable; (4) the intensity distributions of all granules and small granules do not satisfy Gaussian distribution, while that of large granules almost agrees with normal distribution with a peak at 1.04 I 0.

  13. Changes of intranetwork and internetwork functional connectivity in Alzheimer’s disease and mild cognitive impairment

    NASA Astrophysics Data System (ADS)

    Zhu, Haoze; Zhou, Peng; Alcauter, Sarael; Chen, Yuanyuan; Cao, Hongbao; Tian, Miao; Ming, Dong; Qi, Hongzhi; Wang, Xuemin; Zhao, Xin; He, Feng; Ni, Hongyan; Gao, Wei

    2016-08-01

    Objective. Alzheimer’s disease (AD) is a serious neurodegenerative disorder characterized by deficits of working memory, attention, language and many other cognitive functions. Although different stages of the disease are relatively well characterized by clinical criteria, stage-specific pathological changes in the brain remain relatively poorly understood, especially at the level of large-scale functional networks. In this study, we aimed to characterize the potential disruptions of large-scale functional brain networks based on a sample including amnestic mild cognition impairment (aMCI) and AD patients to help delineate the underlying stage-dependent AD pathology. Approach. We sought to identify the neural connectivity mechanisms of aMCI and AD through examination of both intranetwork and internetwork interactions among four of the brain’s key networks, namely dorsal attention network (DAN), default mode network (DMN), executive control network (ECN) and salience network (SAL). We analyzed functional connectivity based on resting-state functional magnetic resonance imaging (rs-fMRI) data from 25 Alzheimer’s disease patients, 20 aMCI patients and 35 elderly normal controls (NC). Main results. Intranetwork functional disruptions within the DAN and ECN were detected in both aMCI and AD patients. Disrupted intranetwork connectivity of DMN and anti-correlation between DAN and DMN were observed in AD patients. Moreover, aMCI-specific alterations in the internetwork functional connectivity of SAL were observed. Significance. Our results confirmed previous findings that AD pathology was related to dysconnectivity both within and between resting-state networks but revealed more spatial details. Moreover, the SAL network, reportedly flexibly coupling either with the DAN or DMN networks during different brain states, demonstrated interesting alterations specifically in the early stage of the disease.

  14. Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

    NASA Technical Reports Server (NTRS)

    Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

    1988-01-01

    The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

  15. Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

    NASA Technical Reports Server (NTRS)

    Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

    1988-01-01

    The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

  16. Spatial and Temporal Variations of Solar Quiet Daily Sq Variation and Equatorial Electrojet Over Africa: Results From International Heliophysical Year

    NASA Astrophysics Data System (ADS)

    Rabiu, A.; Yumoto, K.; Bello, O.

    2010-12-01

    Space Environment Research Centre of Kyushu University, Japan, installed 13 units of Magnetic Data Acquisition Systems MAGDAS over Africa during the International Heliophysical Year IHY. Magnetic records from 10 stations along the African 96o Magnetic Meridian (Geographical 30o - 40o East) were examined for Solar quiet daily Sq variation in the three geomagnetic field components H, D and Z. Spatial variations of Sq in the geomagnetic components were examined. Signatures of equatorial electrojet and worldwide Sq were identified and studied in detail. H field experienced more variation within the equatorial electrojet zone. Diurnal and seasonal variations of the geomagnetic variations in the three components were discussed. Levels of inter-relationships between the Sq and its variability in the three components were statistically derived and interpreted in line with the mechanisms responsible for the variations of the geomagnetic field. Data from 2 magnetic observatories within equatorial electrojet EEJ strip and 2 stations outside the EEJ strip were employed to evaluate and study the signatures of the Equatorial electrojet over the African sector. The transient variations of the EEJ at two almost parallel axes using Lagos-Ilorin and Nairobi-Addis pairs were examined. The EEJ appear stronger in East than West Africa. The magnitudes and patterns of variation of EEJ strength along the two axes were examined for any simultaneity or otherwise of responses to ionospheric processes. The flow gradient of EEJ along the African sector was estimated and its diurnal variation studied.

  17. Long-term variation in the upper atmosphere as seen in the amplitude of the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Hayashi, H.; Nose, M.; Hori, T.; Otsuka, Y.; Tsuda, T.

    2011-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by global ionospheric currents flowing in the E-region from middle latitudes to the magnetic equator. These currents are generated by a dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the thermosphere and ionosphere. From the Ohm's equation, the ionospheric currents strongly depend on the ionospheric conductivity, polarization electric field and neutral wind. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the thermosphere and ionosphere. Elias et al. [2010] found that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes from 1961 to 2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is ionospheric conductivity enhancement associated with cooling effects in the thermosphere due to increasing the greenhouse gases. In this talk, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. These observation data have been provided by the IUGONET (Inter-university Upper atmosphere Global Observation NETwork) project. In the present analysis, we used the F10.7 flux as an indicator of the variation in the solar irradiance in the EUV and UV range, geomagnetic field data with time resolution of 1 hour. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum per day when the Kp index is less than 4. As a result, the Sq amplitude at all the stations strongly depends on 11-year solar activity, and tends to enhance more during the high activities (19- and 22- solar cycles) than during the low activity (20-solar cycle). The Fourier spectra of the F10.7 flux and Sq

  18. Altered Intranetwork and Internetwork Functional Connectivity in Type 2 Diabetes Mellitus With and Without Cognitive Impairment

    PubMed Central

    Yang, Shi-Qi; Xu, Zhi-Peng; Xiong, Ying; Zhan, Ya-Feng; Guo, Lin-Ying; Zhang, Shun; Jiang, Ri-Feng; Yao, Yi-Hao; Qin, Yuan-Yuan; Wang, Jian-Zhi; Liu, Yong; Zhu, Wen-Zhen

    2016-01-01

    Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment. We investigated whether alterations of intranetwork and internetwork functional connectivity with T2DM progression exist, by using resting-state functional MRI. MRI data were analysed from 19 T2DM patients with normal cognition (DMCN) and 19 T2DM patients with cognitive impairment (DMCI), 19 healthy controls (HC). Functional connectivity among 36 previously well-defined brain regions which consisted of 5 resting-state network (RSN) systems [default mode network (DMN), dorsal attention network (DAN), control network (CON), salience network (SAL) and sensorimotor network (SMN)] was investigated at 3 levels (integrity, network and connectivity). Impaired intranetwork and internetwork connectivity were found in T2DM, especially in DMCI, on the basis of the three levels of analysis. The bilateral posterior cerebellum, the right insula, the DMN and the CON were mainly involved in these changes. The functional connectivity strength of specific brain architectures in T2DM was found to be associated with haemoglobin A1c (HbA1c), cognitive score and illness duration. These network alterations in intergroup differences, which were associated with brain functional impairment due to T2DM, indicate that network organizations might be potential biomarkers for predicting the clinical progression, evaluating the cognitive impairment, and further understanding the pathophysiology of T2DM. PMID:27622870

  19. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet (Sq) daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Yatagai, A. I.; Nose, M.; Hori, T.; Otsuka, Y.

    2012-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by the global ionospheric currents flowing in the E-region, which are generated by dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the lower thermosphere and ionosphere. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the lower thermosphere and ionosphere. Recently, Elias et al. [2010] reported that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes in a period of 1961-2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is due to ionospheric conductivity enhancement associated with cooling effect in the thermosphere due to increasing greenhouse gas. In the present study, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. In the present analysis, we used the F10.7 solar flux as a good indicator of the variation in the solar irradiance in the EUV and UV range as well as geomagnetic field data with time resolution of 1 hour observed at 184 geomagnetic stations. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum every day when the Kp index is less than 4. As a result, the long-term variation in the Sq amplitude at all the geomagnetic stations shows a strong correlation with the solar F10.7 flux which depends on 11-year solar activity. The relationship between the Sq amplitude and F10.7 flux was not linear but nonlinear. This nonlinearity could be interpreted as the decrease of production rate of electrons and ions in the ionosphere for the strong EUV and UV fluxes as already reported by Balan et al. [1993]. In order to minimize the solar

  20. The Temperature and Density Structure of the Solar Corona. I. Observations of the Quiet Sun with the EUV Imaging Spectrometer on Hinode

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Brooks, David H.

    2009-07-01

    Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations of current atomic calculations, particularly those for Fe, all conspire to make this task very difficult. A critical assessment of plasma diagnostics in the corona is essential to making progress on the coronal heating problem. In this paper, we present an analysis of temperature and density measurements above the limb in the quiet corona using new observations from the EUV Imaging Spectrometer (EIS) on Hinode. By comparing the Si and Fe emission observed with EIS we are able to identify emission lines that yield consistent emission measure distributions. With these data we find that the distribution of temperatures in the quiet corona above the limb is strongly peaked near 1 MK, consistent with previous studies. We also find, however, that there is a tail in the emission measure distribution that extends to higher temperatures. EIS density measurements from several density sensitive line ratios are found to be generally consistent with each other and with previous measurements in the quiet corona. Our analysis, however, also indicates that a significant fraction of the weaker emission lines observed in the EIS wavelength ranges cannot be understood with current atomic data.

  1. Determination of Geomagnetically Quiet Time Disturbances of the Ionosphere over Uganda during the Beginning of Solar Cycle

    NASA Astrophysics Data System (ADS)

    Habyarimana, Valence

    2016-07-01

    The ionosphere is prone to significant disturbances during geomagnetically active and quiet conditions. This study focused on the occurrence of ionospheric disturbances during geomagnetically quiet conditions. Ionospheric data comprised of Global Positioning System (GPS)-derived Total Electron Content (TEC), obtained over Mt. Baker, Entebbe, and Mbarara International Global Navigation Satellite System (GNSS) Service (IGS) stations. The Disturbance storm time (Dst) index was obtained from Kyoto University website. The number of geomagnetically quiet days in the period under study were first identified. Their monthly percentages were compared for the two years. The monthly percentage of geomagnetically quiet days for all the months in 2009 numerically exceeded those in 2008. December had the highest percentage of geomagnetically quiet days for both years (94 % in 2008 and 100 % in 2009). Geomagnetically quiet days did not show seasonal dependence. The variation in percentage of geomagnetically quiet days during solstice months (May, June, July, November, December, and January) and equinoctial months (February, March, April, August, September, and October) was not uniform. Geomagnetically quiet time disturbances were found to be more significant from 09:00 UT to 13:00 UT. However, there were some other disturbances of small scale amplitude that occurred between 14:00 UT and 22:00 UT. Further analysis was done to identify the satellites that observed the irregularities that were responsible for TEC perturbations. Satellites are identified by Pseudo Random Numbers (PRNs). The ray path between individual PRNs and the corresponding receivers were analysed. Satellites with PRNs: 3, 7, 8, 19 and 21 registered most of the perturbations. It was found that Q disturbances led to fluctuations in density gradients. Significant TEC perturbations were observed on satellite with PRN 21 with receivers at Entebbe and Mbarara on June 28, 2009 between 18:00 UT and 21:00 UT.

  2. Quiet Ride

    ERIC Educational Resources Information Center

    Rathey, Allen

    2006-01-01

    Several companies are marketing maintenance equipment to education institutions on a "quiet platform," citing benefits such as a safer, more pleasant indoor environment and unobtrusive operations during day cleaning or operating hours. This is basically "sound advice" (no one likes noisy equipment), but some of the messages can be confusing and…

  3. Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles

    NASA Astrophysics Data System (ADS)

    Balachandra Swamy, A. C.

    EXTENDED ABSTRACT Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles A.C.Balachandra swmay & Late C.S.G.K. Setty Absorption of radio waves in the ionosphere is of great practical importance for radio communication and navigation systems. The first attempt to measure the absolute magnitude of the radiowave absorption were made by appletion and Ratcliffe (1930) using the frequency change method for medium frequency waves reflected from the E-region. They concluded from their experiment that the main part of the attenuation occurred below the reflection level and named the absorption region, D-region of the ionosphere. One of the basic properties of the ionosphere is the absorption of high Frequency Radiowaves. HF radiowave absorption results mainly from collisions between electrons (which are set into forced oscillations by the electric field of the wave) and neutral air particles, the RF energy abstracted from the wave being converted into thermal energy. The radiowave absorption in the ionosphere depends on electron density and collision frequency. The most important absorbing regions are the D-region and the lower E-region (50-100 Km.) The regular diurnal variation of the electron density in this height range is caused mainly by the changes in the depth of penetration of solar XUV radiations with solar zenith angle under quiet solar conditions. In 1937 Dellinger J.H.identified fade outs in high frequency radio circuits as due to abnormal ionospheric absorption associated with solar flares. The onset of the fade out was usually rapid and the duration was typically tens of minutes like that of the visible flare, because of the sudden onset, the immediate effects of solar flares are known collectively as sudden Ionospheric Disturbances (STD). The phenomenon discovered by Dellinger is usually called a short Wave Fadeout(SWF). Since the SWF is due to abnormal absorption

  4. Analyses of cosmic ray induced-neutron based on spectrometers operated simultaneously at mid-latitude and Antarctica high-altitude stations during quiet solar activity

    NASA Astrophysics Data System (ADS)

    Hubert, G.

    2016-10-01

    In this paper are described a new neutron spectrometer which operate in the Concordia station (Antarctica, Dome C) since December 2015. This instrument complements a network including neutron spectrometers operating in the Pic-du-Midi and the Pico dos Dias. Thus, this work present an analysis of cosmic ray induced-neutron based on spectrometers operated simultaneously in the Pic-du-Midi and the Concordia stations during a quiet solar activity. The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation and effects of local and seasonal changes, but also the short term dynamics during solar flare events. A first part is devoted to analyze the count rates, the spectrum and the neutron fluxes, implying cross-comparisons between data obtained in the both stations. In a second part, measurements analyses were reinforced by modeling based on simulations of atmospheric cascades according to primary spectra which only depend on the solar modulation potential.

  5. OBSERVATION OF HIGH-SPEED OUTFLOW ON PLUME-LIKE STRUCTURES OF THE QUIET SUN AND CORONAL HOLES WITH SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Tian Hui; McIntosh, Scott W.; Habbal, Shadia Rifal; He Jiansen E-mail: mscott@ucar.edu E-mail: jshept@gmail.com

    2011-08-01

    Observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory reveal ubiquitous episodic outflows (jets) with an average speed around 120 km s{sup -1} at temperatures often exceeding a million degree in plume-like structures, rooted in magnetized regions of the quiet solar atmosphere. These outflows are not restricted to the well-known plumes visible in polar coronal holes, but are also present in plume-like structures originating from equatorial coronal holes and quiet-Sun (QS) regions. Outflows are also visible in the 'inter-plume' regions throughout the atmosphere. Furthermore, the structures traced out by these flows in both plume and inter-plume regions continually exhibit transverse (Alfvenic) motion. Our finding suggests that high-speed outflows originate mainly from the magnetic network of the QS and coronal holes (CHs), and that the plume flows observed are highlighted by the denser plasma contained therein. These outflows might be an efficient means to provide heated mass into the corona and serve as an important source of mass supply to the solar wind. We demonstrate that the QS plume flows can sometimes significantly contaminate the spectroscopic observations of the adjacent CHs-greatly affecting the Doppler shifts observed, thus potentially impacting significant investigations of such regions.

  6. Differential energy spectra of low energy (less than 8.5 MeV per nucleon) heavy cosmic rays during solar quiet times. [from Explorer 47 satellite observation

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Vollmer, O.; Gloeckler, G.; Fan, C. Y.

    1973-01-01

    Explorer 47 satellite observations of carbon, oxygen, and heavier nuclei differential energy spectra below 8.5 MeV/nucleon are presented for solar quiet time periods. A dE/dx vs E method for particle identification and energy determination was used. The instrumentation telescope included an isobutane proportional counter, a surface barrier Si detector, and a cylindrical plastic scintillator anticoincidence shield. The observations were performed outside the bow-shock and in the ecliptic plane. Results show an anisotropy of about 25% at 22 degrees west of the sun with a C/O ratio of 0.5 supporting a solar origin. The low energy portions of the C and O spectra have steep negative slopes, and the corresponding power law is given. Peculiarities in the O spectrum are discussed.

  7. PENGUIn/AGO and THEMIS conjugate observations of whistler mode chorus waves in the dayside uniform zone under steady solar wind and quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Keika, Kunihiro; Spasojevic, Maria; Li, Wen; Bortnik, Jacob; Miyoshi, Yoshizumi; Angelopoulos, Vassilis

    2012-07-01

    We perform a case study of conjugate observations of whistler mode chorus waves on the dayside made on 26 July 2008 by three THEMIS spacecraft and ground-based ELF/VLF receivers at the Automatic Geophysical Observatories (AGO) in Antarctica supported by the U.S. Polar Experiment Network for Geospace Upper-atmosphere Investigations (PENGUIn) project. The dayside chorus waves were excited during a period of no substorm activity with geomagnetic indices indicating quiet conditions (Dst ˜ -10 nT; AE < 200 nT). The solar wind dynamic pressure was almost constant during the chorus wave intensification. Conjugate observations in the outer magnetosphere confirm that the chorus intensification was localized within the radial distance R = 7-10 RE near noon (12.5 < MLT < 13.5 h). The waves persisted for at least 1.5 h in the same location, where field lines are not accompanied by off-equatorial minimum-B pockets but rather exhibit nearly zero dB/ds, the field-aligned gradient in B-magnitude, over a wide range of magnetic latitudes (˜±20°). The location did not seem to corotate with the Earth or drift with the energetic electrons. The chorus waves consisted of discrete, rising tone elements, propagating away from the magnetic equator, quasi-parallel to the ambient magnetic field (wave-normal angles < 20°). We conclude that the long-lasting, localized, quiet time dayside chorus amplification was due to the nearly zero dB/ds conditions that occur naturally in the dayside uniform zone (DUZ), the transition region between the near-Earth dipole and the compressed, off-equatorial double-minimum field configuration found closer to the magnetopause. We thus suggest that the magnetic field configuration in the dayside outer magnetosphere plays a key role in the generation of dayside chorus waves under quiet geomagnetic conditions.

  8. USING REALISTIC MHD SIMULATIONS FOR THE MODELING AND INTERPRETATION OF QUIET-SUN OBSERVATIONS WITH THE SOLAR DYNAMICS OBSERVATORY HELIOSEISMIC AND MAGNETIC IMAGER

    SciTech Connect

    Kitiashvili, I. N.; Couvidat, S.; Lagg, A.

    2015-07-20

    The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory. For correct calibration and interpretation of the observations, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, and a spectro-polarimetric radiative transfer code to study observational characteristics of the Fe i 6173 Å line observed by HMI in quiet-Sun regions. We use the modeling results to investigate the sensitivity of the line Doppler shift to plasma velocity, and also sensitivities of the line parameters to plasma temperature and density, and determine effective line formation heights for observations of solar regions located at different distances from the disk center. These estimates are important for the interpretation of helioseismology measurements. In addition, we consider various center-to-limb effects, such as convective blueshift, variations of helioseismic travel-times, and the “concave” Sun effect, and show that the simulations can qualitatively reproduce the observed phenomena, indicating that these effects are related to a complex interaction of the solar dynamics and radiative transfer.

  9. Dependences of statistical characteristics of NmE on the month of the year at middle and low latitudes under daytime geomagnetically quiet conditions at low solar activity

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2016-07-01

    Month-to-month changes in the statistical characteristics of the ionospheric E layer peak electron density NmE at medium and low geomagnetic latitudes under daytime geomagnetically quiet conditions are investigated. Critical frequencies of the ionospheric E layer measured by the middle latitude ionosonde Boulder and low latitude ionosondes Huancayo and Jicamarca at low solar activity from 1957 to 2015 have been used in the conducted statistical analysis. The mathematical expectation of NmE, standard deviation of NmE from the expectation of NmE, and NmE variation coefficient have been calculated for each month of the year. The months of the formation of extrema of these statistical parameters of NmE were found.

  10. Long-term monthly statistics of mid-latitudinal NmF2 in the Northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

    Long-term mid-latitude hourly values of NmF2 measured in 1957-2015 by 10 ionosondes (Point Arguello, Wallops Is., Boulder, de l'Ebre, Rome, Ottawa, Pruhonice, Dourbes, Slough, and Juliusruh) in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of the noon NmF2 for each month, including the mathematical expectation, most probable value, arithmetic average, and arithmetic average median. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). The calculated month-to-month variations of the NmF2 statistical parameters made it possible to study the winter anomaly and spring-autumn asymmetry in these statistical parameters.

  11. Quiet time long term variations of electric fields over São Luís, Brazil, during the last solar minimum (2001-2009)

    NASA Astrophysics Data System (ADS)

    Moro, Juliano; Schuch, Nelson Jorge; Araujo Resende, Laysa Cristina; Marcos Denardini, Clezio; Chen, Sony Su

    Long term variations of vertical and zonal electric fields at Brazilian equatorial E-region heights over São Luís (dip: ~-0.5) are presented. The vertical electric fields estimation includes observations of the type II irregularities embedded in the electrojet current system made with the 50 MHz coherent backscatter (RESCO) radar during quiet time from January 2001 through August 2009. The zonal electric fields are therefore obtained from the vertical electric fields and the Hall-to-Pedersen ionospheric conductivities ratio. The conductivities are field-line-integrated obtained from a conductivity model developed for the Brazilian equatorial E-region. The results are discussed in terms of the local time, seasonal and solar radio flux.

  12. Heating of the quiet solar corona from measurements of the FET/TESIS instrument on-board the KORONAS-FOTON satellite

    NASA Astrophysics Data System (ADS)

    Rybák, J.; Gömöry, P.; Benz, A.; Bogachev, P.; Brajša, R.

    2010-12-01

    The paper presents the first results of the observations of time evolution of the quiet solar corona brightenings obtained due to very rapid photography of the corona with full-disk EUV telescopes of the FET/TESIS instrument onboard the KORONA FOTON satellite. The measurements were performed simultaneously in the emission of the Fe IX / X 17.1 and Fe VIII 13.1 spectral lines with 10 second temporal cadence and spatial scale of 1.7 arc seconds within one hour. This test observation, carried out on 15 July 2009, was analyzed in order to determine whether this type of observation can be used to identify individual microevents in the solar corona heating that are above the tresholds of spatial and temporal resolutions of the observations of non-active regions in the solar atmosphere. For this purpose, a simple method was used involving cross-correlation of the plasma emission time evolution at different temperatures, each time from observations of identical elements. The results obtained are confronted with the expected observable manifestations of the corona heating via nanoflares. TESIS is a set of instruments for the Sun photography developed in the Lebedev Physics Institute of the Russian Academy of Sciences that was launched into orbit in January 2009.

  13. Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

    NASA Astrophysics Data System (ADS)

    Fu, Hui; Madjarska, Maria S.; Xia, LiDong; Li, Bo; Huang, ZhengHua; Wangguan, Zhipeng

    2017-02-01

    Connecting in situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal-hole (CH) wind is bimodal with the slow wind peaking at ∼400 km s‑1 and the fast at ∼600 km s‑1. An anti-correlation between the solar wind speeds and the O7+/O6+ ion ratio remains valid in all three types of solar wind as well during the three studied solar cycle activity phases, i.e., solar maximum, decline, and minimum. The {N}{Fe}/{N}{{O}} range and its average values all decrease with the increasing solar wind speed in different types of solar wind. The {N}{Fe}/{N}{{O}} range (0.06–0.40, first ionization potential (FIP) bias range 1–7) for active region wind is wider than for CH wind (0.06–0.20, FIP bias range 1–3), while the minimum value of {N}{Fe}/{N}{{O}} (∼ 0.06) does not change with the variation of speed, and it is similar for all source regions. The two-peak distribution of CH wind and the anti-correlation between the speed and O7+/O6+ in all three types of solar wind can be explained qualitatively by both the wave-turbulence-driven and reconnection-loop-opening (RLO) models, whereas the distribution features of {N}{Fe}/{N}{{O}} in different source regions of solar wind can be explained more reasonably by the RLO models.

  14. Fourier transform spectrometer observations of solar carbon monoxide. II - Simultaneous cospatial measurements of the fundamental and first-overtone bands, and Ca II K, in quiet and active regions

    NASA Technical Reports Server (NTRS)

    Ayres, T. R.; Testerman, L.; Brault, J. W.

    1986-01-01

    Fourier transform spectrometry has yielded simultaneous cospatial measurements of important diagnostics of thermal structure in the high solar photosphere and low chromosphere. It is noted that the anomalous behavior of the fundamental bands of CO in quiet areas near the limb is accentuated in an active region plage observed close to the limb. The difference between the core temperatures of the CO fundamental bands in a plage and a nearby quiet region at the limb is larger than the corresponding brightness temperature differences in the inner wings of the Ca II line measured in a quiet region and several plages closer to the disk center. Numerical simulations indicate that the disparate behavior of the CO bands with respect to Ca II K cannot be reconciled with existing single component thermal structure models; a two-component atmosphere is required.

  15. On the statistical characteristics of radio-loud and radio-quiet halo coronal mass ejections and their associated flares during solar cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Mittal, Nishant; Sharma, Joginder; Verma, Virendar Kumar; Garg, Vijay

    2016-08-01

    We have studied the characteristics of radio-loud (RL) and radio-quiet (RQ) front side halo coronal mass ejections (HCMEs) (angular width 360°) observed between the time period years 1996-2014. RL-HCMEs are associated with type II radio bursts, while RQ-HCMEs are not associated with type II radio bursts. CMEs near the Sun in the interplanetary medium associated with radio bursts also affect the magnetosphere. The type II radio burst data was observed by WIND/WAVES instrument and HCMEs were observed by LASCO/ SOHO instruments. In our study, we have examined the properties of RL-HCMEs and RQ-HCMEs and found that RL-HCMEs follow the solar cycle variation. Our study also shows that the 26% of slow speed HCMEs and 82% of fast speed HCMEs are RL. The average speed of RL-HCMEs and RQ-HCMEs are 1370 km/s and 727 km/s, respectively. Most of the RQ-HCMEs occur around the solar disc center while most of RL-HCMEs are uniformly distributed across the solar disc. The mean value of acceleration of RL-HCMEs is more than twice that of RQ-HCMEs and mean value of deceleration of RL- HCMEs is very small compare to RQ-HCMEs events. It is also found that RQ-HCMEs events are associated with C- and M-class of SXR flares, while RL-HCMEs events are associated with M and X-class of SXR flares, which indicates that the RQ-HCMEs are less energetic than the RL-HCMEs. We have also discussed the various results obtained in present investigation in view of recent scenario of solar physics.

  16. Observations and Modeling of the Emerging Extreme-ultraviolet Loops in the Quiet Sun as Seen with the Solar Dynamics Observatory

    NASA Astrophysics Data System (ADS)

    Chitta, L. P.; Kariyappa, R.; van Ballegooijen, A. A.; DeLuca, E. E.; Hasan, S. S.; Hanslmeier, A.

    2013-05-01

    We used data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) to study coronal loops at small scales, emerging in the quiet Sun. With HMI line-of-sight magnetograms, we derive the integrated and unsigned photospheric magnetic flux at the loop footpoints in the photosphere. These loops are bright in the EUV channels of AIA. Using the six AIA EUV filters, we construct the differential emission measure (DEM) in the temperature range 5.7-6.5 in log T (K) for several hours of observations. The observed DEMs have a peak distribution around log T ≈ 6.3, falling rapidly at higher temperatures. For log T < 6.3, DEMs are comparable to their peak values within an order of magnitude. The emission-weighted temperature is calculated, and its time variations are compared with those of magnetic flux. We present two possibilities for explaining the observed DEMs and temperatures variations. (1) Assuming that the observed loops are composed of a hundred thin strands with certain radius and length, we tested three time-dependent heating models and compared the resulting DEMs and temperatures with the observed quantities. This modeling used enthalpy-based thermal evolution of loops (EBTEL), a zero-dimensional (0D) hydrodynamic code. The comparisons suggest that a medium-frequency heating model with a population of different heating amplitudes can roughly reproduce the observations. (2) We also consider a loop model with steady heating and non-uniform cross-section of the loop along its length, and find that this model can also reproduce the observed DEMs, provided the loop expansion factor γ ~ 5-10. More observational constraints are required to better understand the nature of coronal heating in the short emerging loops on the quiet Sun.

  17. Solar Cyclical Trend Study of the Mid-Latitude, Quiet-Time, Meridional, Neutral Winds at Winter Solstice Conditions

    DTIC Science & Technology

    1989-01-01

    thermospheric heights [Rishbeth, 1972]. Thermospheric winds blow from the hottest part of the thermosphere to the coldest part and therefore blow across the...19 2. Description of Ionosonde Stations ..... 66 3. Geomagnetic and Solar Data ............ .67 V LIST OF FIGURES Figure Page 1. Vertical temperature ...1977]. . . . . . .................... 12 4. Contour of temperature and winds for winter solstice at solar minimum; (a) meridional winds (m/s), (b) zonal

  18. Changes in solar quiet magnetic variations since the Maunder Minimum: A comparison of historical observations and model simulations

    NASA Astrophysics Data System (ADS)

    Cnossen, Ingrid; Matzka, Jürgen

    2016-10-01

    Magnetic measurements going back to the eighteenth century offer a unique opportunity to study multicentennial changes in the upper atmosphere. We analyzed measurements from Rome and Mannheim from May 1782 to May 1783 and measurements from Greenwich, St. Helena, Cape of Good Hope, and Singapore from May 1841 to May 1842. A comparison of the daily magnetic variations in these historical data with modern-day observations from 2010 at nearby stations (where available) showed notable differences in the amplitude and/or phase of the X and Y components. Model simulations indicated that these can be explained at least to some extent by changes in the Earth's main magnetic field. Changes in the main field strength and the northwestward movement of the magnetic equator, in particular in the region of the South Atlantic Anomaly, have caused changes in the positioning, shape, and strength of the equivalent current vortices in the ionosphere that result in the magnetic perturbations on the ground. Differences in solar activity between the historical and modern epochs, which were all near solar minima, were too small to have a notable effect on the ground magnetic perturbations. However, in regions where main magnetic field changes have been relatively small for the last 400 years, e.g., in Singapore, the effects of a long-term increase in solar activity from Maunder Minimum conditions to normal solar minimum conditions (an increase in F10.7 of 35 solar flux units) were comparable to the effects of geomagnetic main field changes.

  19. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times, 1. On the origin of 200 KeV interplanetary electrons, 2.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.; Ramaty, R.; Fisk, L. A.

    1972-01-01

    A quiet time component of interplanetary electrons having energies above solar wind energies and below those characterized as cosmic radiation was observed. Its energy spectrum falls with energy from 18 keV to 1.8 MeV, but it shows a feature in the 100 to 300 keV range. The observed temporal variations of the intensity suggest that the 18 to 100 keV portion is solar and the 0.3 to 1.8 MeV portion is galactic in origin. Solar and terrestrial neutron decay electrons appear inadequate to explain the 100 to 300 keV feature.

  20. Variations of B0 and B1 with the solar quiet Sq-current system and comparison with IRI-2012 model at Ilorin

    NASA Astrophysics Data System (ADS)

    Bello, S. A.; Abdullah, M.; Hamid, N. S. A.; Yoshikawa, A.; Olawepo, A. O.

    2017-07-01

    The ionospheric thickness (B0) and shape (B1) are bottomside profile parameters introduced by the International Reference Ionosphere (IRI) model. We have validated these parameters with the latest version of the IRI-2012 model and compared them with the solar quiet of geomagnetic H-component (SqH). The B0, B1 and SqH are calculated from the measurements obtained from digisonde DPS-4 sounder and the Magnetic Data Acquisition System (MAGDAS) magnetometer, respectively at Ilorin (geo latitude 8.50°N, geo longitude 4.68°E, and Magnetic dip 4.1°S) an equatorial station in the African sector. The study was for the year 2010, a year of low solar activity (with 27-day averaged solar index, F10.7 = 80 sfu). The results show that B0 for the entire months was higher during the daytime than during the night time. On the other hand, the magnitude of B1during the daytime period is lower than nighttime values and exhibit oscillatory pattern. By comparing the experimental observations of the profile parameters with the IRI-2012 model prediction, we found that B0 was fairly represented by the IRI model options during the nighttime period while discrepancies exist between the model estimates and the experimental values during the morning till midday. A close agreement exists between the observed B1 values and IRI model options. We observed a positive and significant correlation coefficient between B0 and SqH indicating a plausible relationship between these parameters while a weak and negative correlation coefficient between B1 and SqH was observed. We concluded that the difference in the relationship of SqH and the profile parameters B0 and B1 observed can be attributed to their sensitivity to the electric field which is responsible for the E × B drift which in turn modulate the height of the F2.

  1. Regional TEC model under quiet geomagnetic conditions and low-to-moderate solar activity based on CODE GIMs

    NASA Astrophysics Data System (ADS)

    Feng, Jiandi; Jiang, Weiping; Wang, Zhengtao; Zhao, Zhenzhen; Nie, Linjuan

    2017-08-01

    Global empirical total electron content (TEC) models based on TEC maps effectively describe the average behavior of the ionosphere. However, the accuracy of these global models for a certain region may not be ideal. Due to the number and distribution of the International GNSS Service (IGS) stations, the accuracy of TEC maps is geographically different. The modeling database derived from the global TEC maps with different accuracy is likely one of the main reasons that limits the accuracy of the new models. Moreover, many anomalies in the ionosphere are geographic or geomagnetic dependent, and as such the accuracy of global models can deteriorate if these anomalies are not fully incorporated into the modeling approach. For regional models built in small areas, these influences on modeling are immensely weakened. Thus, the regional TEC models may better reflect the temporal and spatial variations of TEC. In our previous work (Feng et al., 2016), a regional TEC model TECM-NEC is proposed for northeast China. However, this model is only directed against the typical region of Mid-latitude Summer Nighttime Anomaly (MSNA) occurrence, which is meaningless in other regions without MSNA. Following the technique of TECM-NEC model, this study proposes another regional empirical TEC model for other regions in mid-latitudes. Taking a small area BeiJing-TianJin-Tangshan (JJT) region (37.5°-42.5° N, 115°-120° E) in China as an example, a regional empirical TEC model (TECM-JJT) is proposed using the TEC grid data from January 1, 1999 to June 30, 2015 provided by the Center for Orbit Determination in Europe (CODE) under quiet geomagnetic conditions. The TECM-JJT model fits the input CODE TEC data with a bias of 0.11TECU and a root mean square error of 3.26TECU. Result shows that the regional model TECM-JJT is consistent with CODE TEC data and GPS-TEC data.

  2. Lower solar chromosphere-corona transition region. III - Implications of the observed quiet-sun emission measure including wave pressure effects

    NASA Technical Reports Server (NTRS)

    Woods, D. Tod; Holzer, Thomas E.; Macgregor, Keith B.

    1990-01-01

    The observed form of the emission measure (EM) is used as a function of temperature to infer the wave energy flux density and pressure throughout the lower transition region (TR). This procedure eliminates the need for specifying how the wave energy flux density is damped and addresses the question of whether there is any form of the mechanical heating associated with the degradation of an upward traveling wave energy flux density which is consistent with the observed EM and other observational constraints for the quiet sun. It is found that the observed form of the EM curve is incompatible with waves traveling vertically at the sound speed, regardless of any filling factor arguments. The same conclusion also applies to waves traveling at the Alfven speed, unless it is assumed that the emission in lower TR lines originates solely from small, spatially unresolved regions of large magnetic field strength (100 G), which cover a small fraction (filling factors of 1 percent) of the solar surface.

  3. Interpretation of second solar spectrum observations of the Sr I 4607 Å line in a quiet region: Turbulent magnetic field strength determination

    NASA Astrophysics Data System (ADS)

    Bommier, V.; Derouich, M.; Landi Degl'Innocenti, E.; Molodij, G.; Sahal-Bréchot, S.

    2005-03-01

    This paper presents and interprets some observations of the limb polarization of Sr I 4607 Å obtained with the spectropolarimeter of the French-Italian telescope THEMIS in quiet regions close to the solar North Pole on 2002 December 7-9. The linear polarization was measured for a series of limb distances ranging from 4 to 160 arcsec, corresponding to heights of optical depth unity in the line core ranging from about 330 to 220 km, respectively, above the τ5000=1 level. To increase the polarimetric sensitivity, the data were averaged along the spectrograph slit (one arcmin long) set parallel to the solar limb. Since the data show no rotation of the linear polarization direction with respect to the limb direction, the observed depolarization is ascribed to the Hanle effect of a turbulent weak magnetic field, the zero-field polarization being derived from a model. The interpretation is performed by means of an algorithm which describes the process of line formation in terms of the atomic density matrix formalism, the solar atmosphere being described by an empirical, plane-parallel model. The collisional rates entering the model (inelastic collisions with electrons, elastic depolarizing collisions with neutral hydrogen), have been computed by applying fast semi-classical methods having a typical accuracy of the order of 20% or better (see Derouich [CITE]), leading to 6% inaccuracy on the magnetic field strength determination. We assume a unimodal distribution for the intensity of the turbulent field. The computed intensity profile has been adjusted to the observed one in both depth and width, by varying both microturbulent and macroturbulent velocities. The best adjustment is obtained for respectively 1.87 km s-1 (micro) and 1.78 km s-1 (macro). The evaluation of the magnetic depolarization leads then to the average value of 46 Gauss for the turbulent magnetic field strength, with a gradient of -0.12 Gauss/km. Our results are in very good agreement with the value of

  4. Dependences of the NmF2 midlatitude statistical characteristics on the month of a year under geomagnetically quiet conditions near noon at low solar activity

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2015-07-01

    The month-to-month variations in the statistical characteristics of the electron density at the mid-latitude ionospheric F2 layer maximum ( NmF2) were studied for geomagnetically quiet conditions near noon. The ionospheric F2 layer critical frequencies, measured by ionosondes in Ashkhabad, Tashkent, Rostov, Irkutsk, Moscow, Sverdlovsk, Tomsk, and Magadan at low solar activity from 1957 to 2013, were used in the performed statistical analysis. The mathematical expectation and the arithmetical mean value of NmF2, the arithmetical mean value of the NmF2 median, and the most probable NmF2 value were calculated for each month. The months with local extremums of these NmF2 statistical characteristics were indicated. It was demonstrated that the semiannual symmetry in the implementation time of local maximums of the NmF2 mathematical expectation, arithmetical mean values, and mean median is observed in the month-to-month variations over Ashkhabad, Tashkent, and Sverdlovsk. The semiannual symmetry of the most probable NmF2 value was found over Ashkhabad. The NmF2 statistical characteristics were compared with one another for each ionosonde at a fixed month. This comparison shows that the values of the most probable NmF2 and the NmF2 mathematical expectation and arithmetically mean median can pronouncedly differ from one another, and the maximal difference of the NmF2 mathematical expectation from the NmF2 arithmetical mean is 0.9%.

  5. An introduction to quiet daily geomagnetic fields

    USGS Publications Warehouse

    Campbell, W.H.

    1989-01-01

    On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in the E region of the earth's ionosphere, are driven by the global thermotidal wind systems, and are dependent upon the local tensor conductivity and main geomagnetic field vector. The highlights of the behavior and interpretation of these quiet field changes, from their discovery in 1634 until the present, are discussed as an introduction to the special journal issue on Quiet Daily Geomagnetic Fields. ?? 1989 Birkha??user Verlag.

  6. Statistical Study of Network Jets Observed in the Solar Transition Region: a Comparison Between Coronal Holes and Quiet-Sun Regions

    NASA Astrophysics Data System (ADS)

    Narang, Nancy; Arbacher, Rebecca T.; Tian, Hui; Banerjee, Dipankar; Cranmer, Steven R.; DeLuca, Ed E.; McKillop, Sean

    2016-04-01

    Recent IRIS observations have revealed a prevalence of intermittent small-scale jets with apparent speeds of 80 - 250 km s^{-1}, emanating from small-scale bright regions inside network boundaries of coronal holes. We find that these network jets appear not only in coronal holes but also in quiet-sun regions. Using IRIS 1330 Å (C II) slit-jaw images, we extracted several parameters of these network jets, e.g. apparent speed, length, lifetime, and increase in foot-point brightness. Using several observations, we find that some properties of the jets are very similar, but others are obviously different between the quiet Sun and coronal holes. For example, our study shows that the coronal-hole jets appear to be faster and longer than those in the quiet Sun. This can be directly attributed to a difference in the magnetic configuration of the two regions, with open magnetic field lines rooted in coronal holes and magnetic loops often present in the quiet Sun. We also detected compact bright loops that are most likely transition region loops and are mostly located in quiet-Sun regions. These small loop-like regions are generally devoid of network jets. In spite of different magnetic structures in the coronal hole and quiet Sun in the transition region, there appears to be no substantial difference for the increase in footpoint brightness of the jets, which suggests that the generation mechanism of these network jets is very likely the same in both regions.

  7. The quiet and disturbed time performance of the IRI 2012 within 90°-130°E longitude sector during solar cycle 24

    NASA Astrophysics Data System (ADS)

    Bhuyan, Pradip; Yokoyama, Tatsuhiro; Supnithi, Pornchai; Kalita, Bitap Raj; Wang, Kehe; Komolmis, Tharadol; Yatini, Clara

    2016-07-01

    The performance of the IRI 2012 model is examined for the double peaked solar cycle 24 in the low latitude region of 90-130oE longitude in the context of the global longitudinal wave number four structure (WN4). The monthly mean values of the foF2 and the hmF2(if available) measurements at low and low mid-latitude stations Dibrugarh (27.5°N, 95°E), Hainan (19.2°N,109.7°E),Okinawa (26.5°N,128°E) and Cocos Island (12.2°S,96.8°E) during quiet times and Dibrugarh (27.5°N, 95°E), Chiang Mai (18.76°N,98.93°E), Chumphon (10.72°N,99.37°E), Kototabang (0.2°S,100.32°E) and Cocos Island (12.2°S,96.8°E ) during the disturbed days of a severe geomagnetic storm are investigated. These stations are located under the strongest peak of the longitudinal WN4 structure in NmF2 along 90-130°E longitudes. The IRI is quite successful in predicting the seasonal averages of NmF2 over this region except in the equinox afternoon period where IRI underestimates the NmF2 in low latitudes. When the monthly mean measured data is compared with IRI, the difference between the IRI model predictions and the measurements are found to follow a systematic pattern. The IRI-2012 with CCIR options slightly underestimates foF2 over Dibrugarh in day time and overestimates in the night time. The amount of underestimation varies from month to month and also depends on the solar activity levels. The IRI also underestimated the day time hmF2 and overestimated the night time hmF2 over Dibrugarh. In case of Hainan, the IRI overestimates the NmF2 in the equinox months and generally in the afternoon to post sunset period. The model values are closer in the solstice than in the equinox. In Okinawa, the trend reverses and the IRI overestimates the NmF2 in the day time and underestimates in the night time. The IRI overestimated the day time hmF2 and underestimated the night time hmF2 over Okinawa. In case of Cocos Island which lies almost on the EIA anomaly region of the southern hemisphere, IRI

  8. Recent Advances in the Exploration of the Small-Scale Structure of the Quiet Solar Atmosphere: Vortex Flows, the Horizontal Magnetic Field, and the Stokes- V Line-Ratio Method

    NASA Astrophysics Data System (ADS)

    Steiner, O.; Rezaei, R.

    2012-05-01

    We review (i) observations and numerical simulations of vortical flows in the solar atmosphere and (ii) measurements of the horizontal magnetic field in quiet Sun regions. First, we discuss various manifestations of vortical flows and emphasize the role of magnetic fields in mediating swirling motion created near the solar surface to the higher layers of the photosphere and to the chromosphere. We reexamine existing simulation runs of solar surface magnetoconvection with regard to vortical flows and compare to previously obtained results. Second, we reviews contradictory results and problems associated with measuring the angular distribution of the magnetic field in quiet Sun regions. Furthermore, we review the Stokes-V-amplitude ratio method for the lines Fe i λλ 630.15 and 630.25 nm. We come to the conclusion that the recently discovered two distinct populations in scatter plots of this ratio must not bee interpreted in terms of “uncollapsed'' and “collapsed'' fields but stem from weak granular magnetic fields and weak canopy fields located at the boundaries between granules and the intergranular space. Based on new simulation runs, we reaffirm earlier findings of a predominance of the horizontal field components over the vertical one, particularly in the upper photosphere and at the base of the chromosphere.

  9. What is magnetically quiet time?

    NASA Astrophysics Data System (ADS)

    Friel, M. M.; Gjerloev, J. W.; Ohtani, S.; Martin, P.; Muhleisen, M.; Olsen, N.; Korth, H.; Foerland, B.

    2015-12-01

    We present the new SuperMAG Disturbance Level indices SMDL_hi (> 55 deg MLat) and SMDL_lo (<55 deg MLat). These indices objectively quantify the external magnetic field perturbations with a 1 min temporal resolution appropriate for the magnetosphere-ionosphere (M-I) system (reconfiguration time ~10 min). The indices are derived from all the ground based magnetometer stations that are part of the SuperMAG collaboration and thus they have the sufficient spatial coverage. Historically the selection of the quietest days (Q-days) and most disturbed days (D-days) of each month is deduced from the Kp indices. Other techniques include the use of magnetic indices and solar wind conditions. Common for these techniques is the long list of assumptions on which they are based. For example: duration of quiet period (e.g. 1 hour or 24 hours), start of quiet periods (e.g. 0 UT), inferred response of the magnetosphere-ionosphere system to solar wind conditions, and the ability of the magnetic indices to quantify the external field contributions (e.g. using only north-south component). We show that previous published techniques include periods of intense substorms and magnetic storms while SMDL effectively excludes these disturbances. The SMDL indices provides more temporal coverage through better quantification of the external field component. We show events, statistics, and we show that the SMDL index provides a powerful tool to quantify the external field contribution.

  10. Characteristics of long-term variation in the amlitude of the geomagnetic solar quiet (Sq) daily variation using the Inter-university Upper atmosphere Gobal Observation NETwork (IUGONET) data analysis system

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.; Otsuka, Y.; Yatagai, A. I.

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet geomagnetic field daily variation (Sq) have been investigated using 1-hour geomagnetic field data obtained from 69 geomagnetic stations in a period of 1947-2013. In the present data analysis, we took advantage of the IUGONET data analysis system. The Sq amplitude clearly showed a 10-12 year solar activity dependence and it tended to enhance during each solar maximum. During the minimum of solar cycle 23/24 in 2008-2009, the Sq amplitude became the smallest in the investigated period. The relationship between the solar F10.7 index and Sq amplitude is approximately linear but 64 percent of geomagnetic stations show a weak nonlinear dependence on the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second order fitting curve between the solar F10.7 index and Sq amplitude during 1947-2013, and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, a majority of the trends in the residual Sq amplitude that passed through a trend test showed a negative value in a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity and residual Sq amplitude showed an anti-correlation for about 71 percent of geomagnetic stations. On the other hand, the residual Sq amplitude in the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies the movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  11. An empirical model of the quiet daily geomagnetic field variation

    USGS Publications Warehouse

    Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-01-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

  12. The NASA quiet engines

    NASA Technical Reports Server (NTRS)

    Ciepluch, C. C.

    1972-01-01

    Efforts to develop an engine noise reduction technology suitable for use on subsonic and conventional takeoff and landing type aircraft are reported. Two baseline quiet engines were developed and tested. The engines were designed with the following quiet features: (1) high bypass ratio engine, (2) large rotor-stator spacing of rotor chords, (3) reduced rotor tip speeds, (4) sound absorbing liners in inlet-outlet ducts, and (5) an optimum ratio from stator to rotor blades. Test results show that if these features are applied to future aircraft, substantial reduction in aircraft noise levels will be obtained.

  13. Rapid and Quiet Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Chang, Zensheu; Bao, Xiaoqi

    2007-01-01

    This describes aspects of the rapid and quiet drill (RAQD), which is a prototype apparatus for drilling concrete or bricks. The design and basic principle of operation of the RAQD overlap, in several respects, with those of ultrasonic/ sonic drilling and coring apparatuses described in a number of previous NASA Tech Briefs articles. The main difference is that whereas the actuation scheme of the prior apparatuses is partly ultrasonic and partly sonic, the actuation scheme of the RAQD is purely ultrasonic. Hence, even though the RAQD generates considerable sound, it is characterized as quiet because most or all of the sound is above the frequency range of human hearing.

  14. Nanoflare Heating of the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Viall, N. M.; Klimchuk, J. A.

    2015-12-01

    How the solar corona is heated to temperatures of over 1 MK, while the photosphere below is only ~ 6000 K remains one of the outstanding problems in all of space science. Solving this problem is crucial for understanding Sun-Earth connections, and will provide new insight into universal processes such as magnetic reconnection and wave-particle interactions. We use a systematic technique to analyze the properties of coronal heating throughout the solar corona using data taken with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our technique computes cooling times of the coronal plasma on a pixel-by-pixel basis and has the advantage that it analyzes all of the coronal emission, including the diffuse emission surrounding distinguishable coronal features. We have already applied this technique to 15 different active regions, and find clear evidence for dynamic heating and cooling cycles that are consistent with the 'impulsive nanoflare' scenario. What about the rest of the Solar corona? Whether the quiet Sun is heated in a similar or distinct manner from active regions is a matter of great debate. Here we apply our coronal heating analysis technique to quiet Sun locations. We find areas of quiet Sun locations that also undergo dynamic heating and cooling cycles, consistent with impulsive nanoflares. However, there are important characteristics that are distinct from those of active regions.

  15. The Quiet Skies Project

    ERIC Educational Resources Information Center

    Rapp, Steve

    2008-01-01

    To help promote student awareness of the connection between radio astronomy and radio frequency interference (RFI), an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project--the result of a collaboration between the National Aeronautics and Space…

  16. The Quiet Skies Project

    ERIC Educational Resources Information Center

    Rapp, Steve

    2008-01-01

    To help promote student awareness of the connection between radio astronomy and radio frequency interference (RFI), an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project--the result of a collaboration between the National Aeronautics and Space…

  17. The vertical propagation of waves in the solar atmosphere. II Phase delays in the quiet chromosphere and cell-network distinctions

    NASA Technical Reports Server (NTRS)

    Lites, B. W.; Chipman, E. G.; White, O. R.

    1982-01-01

    The differences in the phase of the velocity oscillations between a pair of chromospheric Ca II lines was measured using the Vacuum Tower Telescope at the Sacramento Peak Observatory. The observed phase differences indicate that the acoustic modes are trapped or envanescent, rather than propagating, in the chromosphere. Systematic distinctions are found in the phase delays between quiet network and cell interior regions for both intensity and velocity oscillations in photospheric and chromospheric lines. The theory of linear perturbations in an isothermal atmosphere is invoked to interpret these differences. From this analysis it is found that one or more of the following explanations is possible: (1) the radiative damping is more effective in the network than in the cell interior; (2) the network features exclude oscillations of large horizontal wavenumber; or (3) the scale height of the chromosphere is larger in the network than in the cell interior.

  18. Second solar spectrum of the Sr I 4607 Å line: depth probing of the turbulent magnetic field strength in a quiet region

    NASA Astrophysics Data System (ADS)

    Derouich, M.; Bommier, V.; Malherbe, J. M.; Landi Degl'Innocenti, E.

    2006-10-01

    Aims.This paper is devoted to an interpretation of Quiet-Sun, spatially-resolved spectropolarimetric observations of the Hanle effect in terms of turbulent weak magnetic field determination. Methods: . Observations: the slit was positioned perpendicular to the limb, and the spatial resolution along the slit was 1 arcsec, leading to a depth probing along 132 different limb distances. The new polarimeter of the Pic-du-Midi Turret Dome was used on May 14, 2004 to observe a quiet region at the East limb equator in the resonance line of neutral Strontium at 4607 Å. Results: . For each limb distance, we properly adjusted the theoretical intensity profile obtained by applying a zero-field model to the observed one. Micro- and macroturbulent velocities were thus derived (average values v{micro}=1.77 km s-1 and v{macro}=1.95 km s-1). The magnetic field was determined in a second step by interpreting the Hanle effect on the line center linear polarization degree. The depolarizing collisions with neutral hydrogen were taken fully into account through a semi-classical calculation of their rates. An average value of B=38 Gauss was thus derived. Finally, error bars on the magnetic field values were evaluated from a) the polarimetric inaccuracy, b) the limb distance determination inaccuracy, and c) the uncertainty on our theoretical collisional depolarizing rates that we evaluated. This combination leads to 10-20% as total relative error on the magnetic field determination by the Hanle effect method. Since the inaccuracy due to the model itself was hard to properly evaluate, it was ignored. An uncertainty of ±60 km on the line formation depth was, however, derived from the contribution functions. The magnetic field is found to increase slowly with height in the height range 220-300 km above τ5000=1 and then decrease in the height range 300-370 km.

  19. Investigation on Radio-Quiet and Radio-Loud Fast CMEs and Their Associated Flares During Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Suresh, K.; Shanmugaraju, A.

    2015-03-01

    We present the results of a detailed analysis on the differences between radio-loud (RL) and radio-quiet (RQ) fast coronal mass ejections (CMEs) ( V≥900 km s-1) observed during the period 1996 - 2012. The analysis consists of three different steps in which we examined the properties of (i) RL and RQ CMEs, (ii) accelerating (class-A) and decelerating (class-D) CMEs among RL and RQ CMEs, and (iii) associated flares. The last two steps and events from a longer period are the extensions of the earlier work on RL and RQ CMEs that mainly aimed to determine the reason for the radio-quietness of some fast CMEs. During this period, we found that 38 % of fast CMEs are RL and 62 % of fast CMEs are RQ. Moreover, fewer RQ CMEs occur around the disc centre. The average speeds of RL and RQ CMEs are 1358 km s-1 and 1092 km s-1. Around 10 % of the RQ events are halo CMEs, but ≈ 66 % of RL events are halo CMEs. The mean acceleration or deceleration value of RL-CMEs is slightly greater than that of RQ-CMEs. When we divide these events based on their acceleration behaviour into class A and class D, there are no considerable differences between classes A and D of RL-CMEs or between classes A and D of RQ CMEs, except for their initial acceleration values. But there are significant differences among their associated flare properties. According to our study here, the RQ CMEs are less energetic than RL CMEs, and they are not associated with flares as strong as those associated with RL CMEs. This confirms the previous results that RQ CMEs do not often exceed the critical Alfvén speed of 1000 km s-1 in the outer corona that is needed to produce type II radio bursts.

  20. Observations of Quiet Sun Chromosphere Dynamics

    NASA Astrophysics Data System (ADS)

    Verdoni, Angelo; Denker, C.; Deng, N.; Tritschler, A.

    2007-05-01

    The quiet Sun shows a multitude of fine structure in both the photosphere and chromosphere. Observations with high spatial and temporal resolution are required to study their dynamics. In June 2006, simultaneous broad-band continuum (600 nm) and narrow-band spectroscopic (Hα and Na 589.0 nm) data were obtained of a quiet Sun region near disk center using the Dunn Solar Telescope and high-order adaptive optics at the National Solar Observatory/Sacramento Peak. The time-series of continuum data was restored using the speckle masking technique to achieve almost diffraction-limited resolution across the entire field-of-view (80" by 80"). The spectroscopic data were taken with a two-dimensional spectrometer, which is currently being upgraded for spectro-polarimetry. The Visible-light Imaging Magnetograph (VIM) is a telecentric two-dimensional Fabry-Perot based spectro-polarimeter, which will become one of the first-light instruments of the future 1.6-meter New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO). This work was supported by NSF under grants ATM 00-86999, ATM 02-36945, IIS ITR 03-24816, and AST MRI 00-79482 and by NASA under grant NAG 5-12782.

  1. The QUIET Instrument

    NASA Technical Reports Server (NTRS)

    Gaier, T.; Kangaslahti, P.; Lawrence, C. R.; Leitch, E. M.; Wollack, E. J.

    2012-01-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ( approx 1 deg.) . Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 micro Ks(exp 1/2)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 micro Ks(exp 1/2) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01 (QUIET Collaboration 2012) The two arrays together cover multipoles in the range l approximately equals 25-975 . These are the largest HEMT-ba.sed arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument,

  2. Diurnal variation of galactic cosmic ray intensity on quiet days

    NASA Technical Reports Server (NTRS)

    Kumar, S.; Datt, S. C.

    1985-01-01

    A detailed study of the diurnal variation on long term basis was performed on geomagnetically quiet days using the experimental data of the cosmic ray intensity from the worldwide neutron monitoring stations. During the period when the polarity of the solar magnetic field in the Northern Hemisphere of the sun is negative the phase and amplitude of the diurnal anisotropy on quiet days was observed to remain almost constant. When the polarity of solar magnetic field in the Northern Hemisphere changes from negative to positive, a shift in the phase of the diurnal anisotropy on quiet days towards earlier hours is observed and the shift is found to be maximum during minimum solar activity periods 1953-54 and 1975-76. When the polarity of solar magnetic field changes from positive to negative in the Northern Hemisphere of the Sun the phase of the diurnal anisotropy on quiet days recovers to its usual direction of corotational anisotropy and is observed to remain almost constant till the polarity of the solar magnetic field does not change.

  3. Long-term monthly statistics of the mid-latitude ionospheric E-layer peak electron density in the Northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

    Long-term hourly values of the ionospheric E-layer peak electron density, NmE, measured during the time period of 1957-2014 by 4 mid-latitude ionosondes (Wallops Island, Boulder, de l'Ebre, and Rome) in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of NmE close to noon for each month in a year, including the mathematical expectation of NmE, the standard deviations of NmE from the mathematically expected NmE, and the NmE variation coefficient. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). We found that the most probable NmE cannot be considered as the best statistical parameter among the most probable NmE and the mathematically expected NmE in statistical studies of month-to-month variations of NmE. Depending on a choice of an ionosonde and a month, the calculated NmE variation coefficient changes from 5 to 12 %.

  4. The quiet sun

    NASA Technical Reports Server (NTRS)

    Gibson, E. G.

    1973-01-01

    An up-to-date textbook of solar physics is presented. The solar structure and processes, and the interior are described along with the photosphere, the chromosphere, and the corona. The strongest Fraunhofer lines, visible coronal lines, and coronal UV, XUV, and X-ray lines are listed.

  5. The QUIET Instrument

    SciTech Connect

    Bischoff, C.; et al.

    2012-07-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ({approx}1{sup o}). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 {mu}Ks{sup 1/2}) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0:1. The 84-element W-band polarimeter array has a sensitivity of 87 {mu}Ks{sup 1/2} at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0:01. The two arrays together cover multipoles in the range {ell} {approx} 25 -- 975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument.

  6. Quiet powered-lift propulsion

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Latest results of programs exploring new propulsion technology for powered-lift aircraft systems are presented. Topics discussed include results from the 'quiet clean short-haul experimental engine' program and progress reports on the 'quiet short-haul research aircraft' and 'tilt-rotor research aircraft' programs. In addition to these NASA programs, the Air Force AMST YC 14 and YC 15 programs were reviewed.

  7. Observations of the quiet Sun from the soft x ray telescope on Yohkoh

    NASA Technical Reports Server (NTRS)

    Strong, Keith T.

    1992-01-01

    The Soft X-ray Telescope (SXT) on Yohkoh has obtained many thousands of images suitable for studying the quiet Sun. It will give a new perspective on the types of structures, their frequency of occurrence, and their lifetimes that will provide an invaluable tool for planning SOHO (Solar and Heliospheric Observatory) observations of the solar corona. The range of corona phenomena and the dynamic nature of the quiet Sun are illustrated.

  8. Observations of the quiet Sun from the soft x ray telescope on Yohkoh

    NASA Technical Reports Server (NTRS)

    Strong, Keith T.

    1992-01-01

    The Soft X-ray Telescope (SXT) on Yohkoh has obtained many thousands of images suitable for studying the quiet Sun. It will give a new perspective on the types of structures, their frequency of occurrence, and their lifetimes that will provide an invaluable tool for planning SOHO (Solar and Heliospheric Observatory) observations of the solar corona. The range of corona phenomena and the dynamic nature of the quiet Sun are illustrated.

  9. A Mostly Quiet Pacific

    NASA Image and Video Library

    2003-11-18

    Some climate forecast models indicate there is an above average chance that there could be a weak to borderline El Niño by the end of November 2003. However, the trade winds, blowing from east to west across the equatorial Pacific Ocean, remain strong. Thus, there remains some uncertainty among climate scientists as to whether the warm temperature anomaly will form again this year. The latest remote sensing data from NASA's Jason satellite show near normal conditions across the equatorial Pacific. There are currently no visible signs in sea surface height of an impending El Niño. This equatorial quiet contrasts with the Bering Sea, Gulf of Alaska and U.S. West Coast where lower-than-normal sea surface levels and cool ocean temperatures continue (indicated by blue and purple areas). The image above is a global map of sea surface height, accurate to within 30 millimeters. The image represents data collected and composited over a 10-day period, ending on Nov. 3, 2003. The height of the water relates to the temperature of the water. As the ocean warms, its level rises; and as it cools, its level falls. Yellow and red areas indicate where the waters are relatively warmer and have expanded above sea level, green indicates near normal sea level, and blue and purple areas show where the waters are relatively colder and the surface is lower than sea level. The blue areas are between 5 and 13 centimeters (2 and 5 inches) below normal, whereas the purple areas range from 14 to 18 centimeters (6 to 7 inches) below normal. http://photojournal.jpl.nasa.gov/catalog/PIA04878

  10. MAGNETIC BRIGHT POINTS IN THE QUIET SUN

    SciTech Connect

    Sanchez Almeida, J.; Bonet, J. A.; Viticchie, B.

    2010-05-20

    We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0.''1 angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs Mm{sup -2}, which is a factor 3 larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs contribute to the solar magnetic flux with an unsigned flux density between 13 G and 33 G. If network and inter-network regions are counted separately, they contain 2.2 BPs Mm{sup -2} and 0.85 BPs Mm{sup -2}, respectively.

  11. Ubiquitous quiet-Sun jets

    NASA Astrophysics Data System (ADS)

    Martínez Pillet, V.; Del Toro Iniesta, J. C.; Quintero Noda, C.

    2011-06-01

    Context. IMaX/Sunrise has recently reported the temporal evolution of highly dynamic and strongly Doppler shifted Stokes V signals in the quiet Sun. Aims: We attempt to identify the same quiet-Sun jets in the Hinode spectropolarimeter (SP) data set. Methods: We generate combinations of linear polarization magnetograms with blue- and redshifted far-wing circular polarization magnetograms to allow an easy identification of the quiet-Sun jets. Results: The jets are identified in the Hinode data where both red- and blueshifted cases are often found in pairs. They appear next to regions of transverse fields that exhibit quiet-Sun neutral lines. They also have a clear tendency to occur in the outer boundary of the granules. These regions always display highly displaced and anomalous Stokes V profiles. Conclusions: The quiet Sun is pervaded with jets formed when new field regions emerge at granular scales loaded with horizontal field lines that interact with their surroundings. This interaction is suggestive of some form of reconnection of the involved field lines that generates the observed high speed flows.

  12. Near IR observations of Quiet Chromosphere

    NASA Astrophysics Data System (ADS)

    Prasad Choudhary, Debi; Deng, N.; Tejamoortula, U.; Penn, M. J.

    2009-05-01

    We have carried out the observations of quiet solar limb during April 29 to May 1, 2008, March 9-13, 2009 using the vertical spectrograph at the focal plane of McMath-Pierce telescope at Kitt Peak National Observatory. The solar limb was mostly featureless during the observations. The New Infrared Array (NAC) at the exit port of the spectrograph has been used to record the limb spectrum at HeI 1083.0 nm, Hydrogen Paschen beta at 1281.8 nm and Brackett gamma 2165.5 nm wavelength regions. The NAC is a 1024 x 1024 InSb Alladin III Detector operating over 1-5 micron range with high density sampling at 0.018 arc second/pixel. The all-reflective optical train minimizes number of surfaces and eliminates ghosts leading to low scatter, ghost-free optics. The close-cycle cryogenic provides a stable cooling environment over six hour period with an accuracy of about 0.01K leading to low dark current. The low read out noise combined with low scattered light and dark current makes NAC an ideal detector for making high quality infrared spectral observations of solar limb. In this presentation, we shall compare the line parameters of these lines around the solar disk. Acknowledgements: This work is supported by NSF under grant ATM 05-48952 and by NASA under grant NNX08AQ32G.

  13. Looking for Peace and Quiet

    ERIC Educational Resources Information Center

    Palin, Ray

    2014-01-01

    Ray Palin, librarian at Sunapee Middle High School in Sunapee, New Hampshire describes what it takes to make the school library a space for those looking for "peace and quiet." Palin begins this article by noting that much has been written about the advantages associated with the learning commons model of library design, however less has…

  14. Looking for Peace and Quiet

    ERIC Educational Resources Information Center

    Palin, Ray

    2014-01-01

    Ray Palin, librarian at Sunapee Middle High School in Sunapee, New Hampshire describes what it takes to make the school library a space for those looking for "peace and quiet." Palin begins this article by noting that much has been written about the advantages associated with the learning commons model of library design, however less has…

  15. Quiet Sun and its Dynamics as Viewed from the Ground and from Space

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.

    2016-04-01

    Over the last years, state-of-the-art ground-based and/or space-based observations using imaging, spectroscopic and spectropolarimetric instruments, at a wide range of wavelengths, reveal that the quiet Sun, just like active regions, is a highly inhomogeneous and dynamic environment that plays an important role in the dynamics of the entire solar atmosphere. This dynamic quiet Sun is manifested through a number of different types of features and phenomena that occur in a large range of spatial and temporal scales and are nowadays believed to be mostly driven by the local magnetic field and its dynamics. Ground-based observations processed with state-of-the-art, post-processing reconstruction techniques, often combined with simultaneous space-based observations from a variety of instruments on different spacecraft, offer a unique opportunity to investigate and understand the physical conditions of the local plasma, the nature, formation mechanisms and evolution of quiet Sun phenomena and possible interrelationships between quiet Sun phenomena occurring at different heights of the quiet Sun solar atmosphere, from the photosphere and chromosphere to the transition region and low corona. We provide a comprehensive review of our latest understanding of quiet Sun and its dynamics as viewed from the ground and from space and discuss the advantages/disadvantages of ground- and space-based observations and future advents in solar observations with new solar instruments.

  16. Energy Input Flux in the Global Quiet-Sun Corona

    NASA Astrophysics Data System (ADS)

    Mac Cormack, Cecilia; Vásquez, Alberto M.; López Fuentes, Marcelo; Nuevo, Federico A.; Landi, Enrico; Frazin, Richard A.

    2017-07-01

    We present first results of a novel technique that provides, for the first time, constraints on the energy input flux at the coronal base (r ˜ 1.025 R ⊙) of the quiet Sun at a global scale. By combining differential emission measure tomography of EUV images, with global models of the coronal magnetic field, we estimate the energy input flux at the coronal base that is required to maintain thermodynamically stable structures. The technique is described in detail and first applied to data provided by the Extreme Ultraviolet Imager instrument, on board the Solar TErrestrial RElations Observatory mission, and the Atmospheric Imaging Assembly instrument, on board the Solar Dynamics Observatory mission, for two solar rotations with different levels of activity. Our analysis indicates that the typical energy input flux at the coronal base of magnetic loops in the quiet Sun is in the range ˜0.5-2.0 × 105 (erg s-1 cm-2), depending on the structure size and level of activity. A large fraction of this energy input, or even its totality, could be accounted for by Alfvén waves, as shown by recent independent observational estimates derived from determinations of the non-thermal broadening of spectral lines in the coronal base of quiet-Sun regions. This new tomography product will be useful for the validation of coronal heating models in magnetohydrodinamic simulations of the global corona.

  17. The heating of the solar chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang

    1991-01-01

    The solar atmosphere associated with magnetic fields is brighter in characteristic field emitters than the magnetic field-free portion of the atmosphere. The chromosphere can accordingly be identified with the atmosphere within such magnetic elements as flux tubes. Attention is presently given to bright points associated with the intranetwork magnetic fields, which are heated by large-amplitude compressive waves whose periods approximate the 3-min acoustic cutoff period. Relevant line and continuum radiation observations are studied; it is concluded that energy dissipated by the 3-min waves may suffice to heat the low and middle chromosphere, in the bright points, to the temperatures observed.

  18. Modeling the Quiet Time Outflow Solution in the Polar Cap

    NASA Technical Reports Server (NTRS)

    Glocer, Alex

    2011-01-01

    We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.

  19. The Quiet Explosion

    NASA Astrophysics Data System (ADS)

    2008-07-01

    weak and 'soft' [1], very different from a gamma-ray burst and more in line with what is expected from a normal supernova." So, after the supernova was discovered, the team rapidly observed it from the Asiago Observatory in Northern Italy and established that it was a Type Ic supernova. "These are supernovae produced by stars that have lost their hydrogen and helium-rich outermost layers before exploding, and are the only type of supernovae which are associated with (long) gamma-ray bursts," explains Mazzali. "The object thus became even more interesting!" Earlier this year, an independent team of astronomers reported in the journal Nature that SN 2008D is a rather normal supernova. The fact that X-rays were detected was, they said, because for the first time, astronomers were lucky enough to catch the star in the act of exploding. Mazzali and his team think otherwise. "Our observations and modeling show this to be a rather unusual event, to be better understood in terms of an object lying at the boundary between normal supernovae and gamma-ray bursts." The team set up an observational campaign to monitor the evolution of the supernova using both ESO and national telescopes, collecting a large quantity of data. The early behaviour of the supernova indicated that it was a highly energetic event, although not quite as powerful as a gamma-ray burst. After a few days, however, the spectra of the supernova began to change. In particular Helium lines appeared, showing that the progenitor star was not stripped as deeply as supernovae associated with gamma-ray bursts. Over the years, Mazzali and his group have developed theoretical models to analyse the properties of supernovae. When applied to SN2008D, their models indicated that the progenitor star was at birth as massive as 30 times the Sun, but had lost so much mass that at the time of the explosion the star had a mass of only 8-10 solar masses. The likely result of the collapse of such a massive star is a black hole

  20. The NASA quiet engine program

    NASA Technical Reports Server (NTRS)

    Kramer, J. J.; Montegani, F. J.

    1972-01-01

    Initial studies on the design and testing of the quiet engine are described. The principal noise sources considered in the engine selection were the fan machinery noise and the fan and core jet noise. Nacelle acoustic linings are also mentioned. Fan and engine tests are discussed briefly and results indicate that it is possible to achieve or exceed noise reduction objectives of 15 to 20 PNdb below the levels of 707/DC-8 long-range transport aircraft.

  1. Low-frequency heliographic observations of the quiet Sun corona

    NASA Astrophysics Data System (ADS)

    Stanislavsky, A. A.; Koval, A. A.; Konovalenko, A. A.

    2013-12-01

    We present new results of heliographic observations of quiet-Sun radio emission fulfilled by the UTR-2 radio telescope. The solar corona investigations have been made close to the last solar minimum (Cycle 23) in the late August and early September of 2010 by means of the two-dimensional heliograph within 16.5-33 MHz. Moreover, the UTR-2 radio telescope was used also as an 1-D heliograph for one-dimensional scanning of the Sun at the beginning of September 2010 as well as in short-time observational campaigns in April and August of 2012. The average values of integral flux density of the undisturbed Sun continuum emission at different frequencies have been found. Using the data, we have determined the spectral index of quiet-Sun radio emission in the range 16.5-200 MHz. It is equal to -2.1±0.1. The brightness distribution maps of outer solar corona at frequencies 20.0 MHz and 26.0 MHz have been obtained. The angular sizes of radio Sun were estimated. It is found that the solar corona at these frequencies is stretched-out along equatorial direction. The coefficient of corona ellipticity varies slightly during above period. Its mean magnitudes are equal to ≈ 0.75 and ≈ 0.73 at 20.0 MHz and 26.0 MHz, respectively. The presented results for continuum emission of solar corona conform with being ones at higher frequencies.

  2. STATISTICAL ANALYSIS OF THE VERY QUIET SUN MAGNETISM

    SciTech Connect

    Martinez Gonzalez, M. J.; Manso Sainz, R.; Asensio Ramos, A.

    2010-03-10

    The behavior of the observed polarization amplitudes with spatial resolution is a strong constraint on the nature and organization of solar magnetic fields below the resolution limit. We study the polarization of the very quiet Sun at different spatial resolutions using ground- and space-based observations. It is shown that 80% of the observed polarization signals do not change with spatial resolution, suggesting that, observationally, the very quiet Sun magnetism remains the same despite the high spatial resolution of space-based observations. Our analysis also reveals a cascade of spatial scales for the magnetic field within the resolution element. It is manifest that the Zeeman effect is sensitive to the microturbulent field usually associated with Hanle diagnostics. This demonstrates that Zeeman and Hanle studies show complementary perspectives of the same magnetism.

  3. Microbial proteomics: the quiet revolution

    SciTech Connect

    Seraphin, Bertrand; Hettich, Robert {Bob} L

    2012-01-01

    Technological developments in DNA sequencing and their application to study thousands of microbial genomes or even microbial ecosystems still today often make the headlines of general newspapers and scientific journals. These revolutionary changes are hiding another revolution that is unfolding more quietly in the background: the development of microbial proteomics to study genome expression products. It is important to recognize that while DNA sequencing reveals extensive details about the genomic potential of an organism or community, proteomic measurements reveal the functional gene products that are present and operational under specific environmental conditions, and thus perhaps better characterize the critical biomolecules that execute the life processes (enzymes, signaling, structural factors, etc.).

  4. MAGNETIC LOOPS IN THE QUIET SUN

    SciTech Connect

    Wiegelmann, T.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Borrero, J. M.; Schmidt, W.; Pillet, V. MartInez; Bonet, J. A.; Domingo, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields.

  5. A Quiet Place for Student Veterans

    ERIC Educational Resources Information Center

    Hollingsworth, Margaret

    2015-01-01

    As electronic gadgets predominate a student's life, there comes a need for silence. A quiet place free of electromagnetic spectrum waves, dirty and stray electricity, and the endless chirps, whistles, beeps, and customized signaling. A quiet place can offer solitude for meditation, inspiration, and spiritual awareness. Student involvement in the…

  6. Studies Highlight Classroom Plight of Quiet Students

    ERIC Educational Resources Information Center

    Sparks, Sarah D.

    2012-01-01

    Educators often look for ways to bring quiet children out of their shells, but emerging research suggests schools can improve academic outcomes for introverted students by reducing the pressure to be outgoing and giving all students a little more time to reflect. A 2011 study found teachers from across K-12 rated hypothetical quiet children as…

  7. A Quiet Place for Student Veterans

    ERIC Educational Resources Information Center

    Hollingsworth, Margaret

    2015-01-01

    As electronic gadgets predominate a student's life, there comes a need for silence. A quiet place free of electromagnetic spectrum waves, dirty and stray electricity, and the endless chirps, whistles, beeps, and customized signaling. A quiet place can offer solitude for meditation, inspiration, and spiritual awareness. Student involvement in the…

  8. Studies Highlight Classroom Plight of Quiet Students

    ERIC Educational Resources Information Center

    Sparks, Sarah D.

    2012-01-01

    Educators often look for ways to bring quiet children out of their shells, but emerging research suggests schools can improve academic outcomes for introverted students by reducing the pressure to be outgoing and giving all students a little more time to reflect. A 2011 study found teachers from across K-12 rated hypothetical quiet children as…

  9. First results on quiet and magnetic granulation from SOUP

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan, D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill, M.

    1987-01-01

    The flight of Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 allowed the collection of time sequences of diffraction limited (0.5 arc sec) granulation images with excellent pointing (0.003 arc sec) and completely free of the distortion that plagues groundbased images. The p-mode oscillations are clearly seen in the data. Using Fourier transforms in the temporal and spatial domain, it was shown that the p-modes dominate the autocorrelation lifetime in magnetic regions. When these oscillations are removed the autocorrelation lifetime is found to be 500 sec in quiet and 950 sec in magnetic regions. In quiet areas exploding granules are seen to be common. It is speculated that a significant fraction of granule lifetimes are terminated by nearby explosions. Using local correlation tracking techniques it was able to measure horizontal displacements, and thus transverse velocities, in the magnetic field. In quiet sun it is possible to detect both super and mesogranulation. Horizontal velocities are as great as 1000 m/s and the average velocity is 400 m/s. In magnetic regions horizontal velocities are much less, about 100 m/s.

  10. Small-scale eruptive filaments on the quiet sun

    NASA Technical Reports Server (NTRS)

    Hermans, Linda M.; Martin, Sara F.

    1986-01-01

    A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments.

  11. Statistical Characteristics of EMIC Waves Observed at Geosynchronous Orbit during Quiet Geomagnetic Conditions

    NASA Astrophysics Data System (ADS)

    Park, J. S.; Kim, K. H.; Lee, D. H.; Lee, E.; Jin, H.

    2014-12-01

    It is generally accepted that the electromagnetic ion cyclotron (EMIC) waves can be generated under the conditions of anisotropic (T⊥ > T∥) and energetic (larger than a few tens keV) ion population. Such conditions are expected when the magnetospheric convection is enhanced or when the magnetosphere is compressed by solar wind dynamic pressure enhancement. Even in the absence of strong magnetospheric convection or strong solar wind dynamic pressure enhancements, we have observed EMIC waves at geosynchronous orbit. In this study, we report the GOES observations of the EMIC waves excited during quiet geomagnetic conditions (Kp ≤ 1) in the period from January 2007 to December in 2008. Unlike previous studies, the occurrence rate of quiet time EMIC waves is dominant in morning-to-afternoon sector. We will examine the source of free energy to excite quiet time EMIC waves and also examine wave's characteristics.

  12. Magnetospheric convection during quiet or moderately disturbed times

    NASA Technical Reports Server (NTRS)

    Caudal, G.; Blanc, M.

    1988-01-01

    The processes which contribute to the large-scale plasma circulation in the earth's environment during quiet times, or during reasonable stable magnetic conditions are reviewed. The various sources of field-aligned current generation in the solar wind and the magnetosphere are presented. The generation of field-aligned currents on open field lines connected to either polar cap and the generation of closed field lines of the inner magnetosphere are examined. Consideration is given to the hypothesis of Caudal (1987) that loss processes of trapped particles are competing with adiabatic motions in the generation of field-aligned currents in the inner magnetosphere.

  13. High-torque quiet gear

    NASA Astrophysics Data System (ADS)

    Moody, Paul E.

    1995-07-01

    A high-torque quiet gear construction consists of an inner hub having a plurality of circumferentially spaced arms extending radially outwardly therefrom, and an outer ring member having a plurality of circumferentially spaced-teeth extending radially inwardly therefrom. The ring member further includes a plurality of gear formations on an outer surface thereof for intermeshing with other gears. The teeth of the ring member are received in spaced relation in corresponding spaces formed between adjacent arms of the hub. An elastomeric member is received in the space formed between the hub and the ring member to form a resilient correction between the arms of the hub and the teeth of the ring member. The side surfaces of the arms and the teeth extend generally parallel to each other and at least partially overlap in a longitudinal direction. The purpose of this configuration is to place the elastomeric member in compression when torque is applied to the hub. Since elastomeric material is relatively incompressible, the result is low shear loads on the adhesive bonds which hold the elastomeric member to both the hub and outer ring member.

  14. Quiet Supersonic Wind Tunnel Development

    NASA Technical Reports Server (NTRS)

    King, Lyndell S.; Kutler, Paul (Technical Monitor)

    1994-01-01

    The ability to control the extent of laminar flow on swept wings at supersonic speeds may be a critical element in developing the enabling technology for a High Speed Civil Transport (HSCT). Laminar boundary layers are less resistive to forward flight than their turbulent counterparts, thus the farther downstream that transition from laminar to turbulent flow in the wing boundary layer is extended can be of significant economic impact. Due to the complex processes involved experimental studies of boundary layer stability and transition are needed, and these are performed in "quiet" wind tunnels capable of simulating the low-disturbance environment of free flight. At Ames, a wind tunnel has been built to operate at flow conditions which match those of the HSCT laminar flow flight demonstration 'aircraft, the F-16XL, i.e. at a Mach number of 1.6 and a Reynolds number range of 1 to 3 million per foot. This will allow detailed studies of the attachment line and crossflow on the leading edge area of the highly swept wing. Also, use of suction as a means of control of transition due to crossflow and attachment line instabilities can be studied. Topics covered include: test operating conditions required; design requirements to efficiently make use of the existing infrastructure; development of an injector drive system using a small pilot facility; plenum chamber design; use of computational tools for tunnel and model design; and early operational results.

  15. NASA's Quiet Aircraft Technology Project

    NASA Technical Reports Server (NTRS)

    Whitfield, Charlotte E.

    2004-01-01

    NASA's Quiet Aircraft Technology Project is developing physics-based understanding, models and concepts to discover and realize technology that will, when implemented, achieve the goals of a reduction of one-half in perceived community noise (relative to 1997) by 2007 and a further one-half in the far term. Noise sources generated by both the engine and the airframe are considered, and the effects of engine/airframe integration are accounted for through the propulsion airframe aeroacoustics element. Assessments of the contribution of individual source noise reductions to the reduction in community noise are developed to guide the work and the development of new tools for evaluation of unconventional aircraft is underway. Life in the real world is taken into account with the development of more accurate airport noise models and flight guidance methodology, and in addition, technology is being developed that will further reduce interior noise at current weight levels or enable the use of lighter-weight structures at current noise levels.

  16. Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Lieber, Lysbeth; Repp, Russ; Weir, Donald S.

    1996-01-01

    A calibration of the acoustic and aerodynamic prediction methods was performed and a baseline fan definition was established and evaluated to support the quiet high speed fan program. A computational fluid dynamic analysis of the NASA QF-12 Fan rotor, using the DAWES flow simulation program was performed to demonstrate and verify the causes of the relatively poor aerodynamic performance observed during the fan test. In addition, the rotor flowfield characteristics were qualitatively compared to the acoustic measurements to identify the key acoustic characteristics of the flow. The V072 turbofan source noise prediction code was used to generate noise predictions for the TFE731-60 fan at three operating conditions and compared to experimental data. V072 results were also used in the Acoustic Radiation Code to generate far field noise for the TFE731-60 nacelle at three speed points for the blade passage tone. A full 3-D viscous flow simulation of the current production TFE731-60 fan rotor was performed with the DAWES flow analysis program. The DAWES analysis was used to estimate the onset of multiple pure tone noise, based on predictions of inlet shock position as a function of the rotor tip speed. Finally, the TFE731-60 fan rotor wake structure predicted by the DAWES program was used to define a redesigned stator with the leading edge configured to minimize the acoustic effects of rotor wake / stator interaction, without appreciably degrading performance.

  17. Near field zones of quiet

    NASA Astrophysics Data System (ADS)

    Joseph, P.; Elliott, S. J.; Nelson, P. A.

    1994-05-01

    This paper examines the consequences of driving a single secondary loudspeaker to cancel the pressure due to some primary source at a point in its near field. This simple technique has been applied to the sound field in a highly reverberant room to produce zones of quiet in the vicinity of the loudspeaker, which have diameters that are typically equal to one-tenth of the acoustic wavelength, within which the sound pressure level is attenuated by at least 10 dB. The principal advantage gained with this strategy over other active techniques for controlling the sound field in rooms is that the sound pressure level well away from the control point is largely unaffected, an increase of only a small fraction of one dB being typical. Such a loudspeaker-microphone configuration could be located, for example, in the head rests of cars or aeroplanes, or indeed anywhere where the listener is seated for significant lengths of time and subjected to high ambient noise levels such that auditory comfort may be disturbed.

  18. Quiet Supersonic Technology (QueSST)

    NASA Image and Video Library

    2017-03-02

    Mechanical technician Dan Pitts prepares a scale model of Lockheed Martin's Quiet Supersonic Technology (QueSST) X-plane preliminary design for its first high-speed wind tunnel tests at NASA's Glenn Research Center.

  19. The Effect of Quiet on Hearing

    DTIC Science & Technology

    1975-01-01

    34Biomechanics of Ahi Force Operations," Task 723103, "Effects of Operational Noise On Air Force Personnel," and Work Unit 016, "Auditory Responses to... problem . PURPOSE The purpose of this study was to determine the amount of time in quiet required fi ihe hearing threshold levels of experimental...but were not allowed to sleep . Following the period of quiet, and a signal from the experimenter, the headset was replaced by the subject and postqtiet

  20. ON THE PROBABLE EXISTENCE OF AN ABRUPT MAGNETIZATION IN THE UPPER CHROMOSPHERE OF THE QUIET SUN

    SciTech Connect

    Stepan, JirI; Trujillo Bueno, Javier E-mail: jtb@iac.es

    2010-03-10

    We report on a detailed radiative transfer modeling of the observed scattering polarization in the H{alpha} line, which allows us to infer quantitative information on the magnetization of the quiet solar chromosphere. Our analysis suggests the presence of a magnetic complexity zone with a mean field strength (B) > 30 G lying just below the sudden transition region to the coronal temperatures. The chromospheric plasma directly underneath is very weakly magnetized, with (B) {approx} 1 G. The possible existence of this abrupt change in the degree of magnetization of the upper chromosphere of the quiet Sun might have large significance for our understanding of chromospheric (and, therefore, coronal) heating.

  1. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... and Intermediate Partial Quiet Zones? 222.42 Section 222.42 Transportation Other Regulations Relating... Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones and..., if the public authority provides Notice of Quiet Zone Continuation, in accordance with § 222.43...

  2. A substantial amount of hidden magnetic energy in the quiet Sun.

    PubMed

    Bueno, J Trujillo; Shchukina, N; Ramos, A Asensio

    2004-07-15

    Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal heating. At present, we can see only approximately 1 per cent of the complex magnetism of the quiet Sun, which highlights the need to develop a reliable way to investigate the remaining 99 per cent. Here we report three-dimensional radiative transfer modelling of scattering polarization in atomic and molecular lines that indicates the presence of hidden, mixed-polarity fields on subresolution scales. Combining this modelling with recent observational data, we find a ubiquitous tangled magnetic field with an average strength of approximately 130 G, which is much stronger in the intergranular regions of solar surface convection than in the granular regions. So the average magnetic energy density in the quiet solar photosphere is at least two orders of magnitude greater than that derived from simplistic one-dimensional investigations, and sufficient to balance radiative energy losses from the solar chromosphere.

  3. What Is the Source of Quiet Sun Transition Region Emission?

    NASA Astrophysics Data System (ADS)

    Schmit, D. J.; De Pontieu, Bart

    2016-11-01

    Dating back to the first observations of the on-disk corona, there has been a qualitative link between the photosphere’s magnetic network and enhanced transition-temperature plasma emission. These observations led to the development of a general model that describes emission structures through the partitioning of the atmospheric volume with different magnetic loop geometries that exhibit different energetic equilibria. Does the internetwork produce transition-temperature emission? What fraction of network flux connects to the corona? How does quiet Sun emission compare with low-activity Sun-like stars? In this work, we revisit the canonical model of the quiet Sun, with high-resolution observations from the Interface Region Imaging Spectrograph (IRIS) and HMI in hand, to address those questions. We use over 900 deep exposures of Si iv 1393 Å from IRIS along with nearly simultaneous HMI magnetograms to quantify the correlation between transition-temperature emission structures and magnetic field concentrations through a number of novel statistics. Our observational results are coupled with analysis of the Bifrost MHD model and a large-scale potential field model. Our results paint a complex portrait of the quiet Sun. We measure an emission signature in the distant internetwork that cannot be attributed to network contribution. We find that the dimmest regions of emission are not linked to the local vertical magnetic field. Using the MHD simulation, we categorize the emission contribution from cool mid-altitude loops and high-altitude coronal loops and discuss the potential emission contribution of spicules. Our results provide new constraints on the coupled solar atmosphere so that we can build on our understanding of how dynamic thermal and magnetic structures generate the observed phenomena in the transition region.

  4. Temperature and Density Measurements in a Quiet Coronal Streamer

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Warshall, Andrew D.

    2002-06-01

    Many previous studies have used emission line or broadband filter ratios to infer the presence of temperature gradients in the quiet solar corona. Recently it has been suggested that these temperature gradients are not real, but result from the superposition of isothermal loops with different temperatures and density scale heights along the line of sight. A model describing this hydrostatic weighting bias has been developed by Aschwanden & Acton. In this paper we present the application of the Aschwanden & Acton differential emission measure model to Solar and Heliospheric Observatory Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a quiet coronal streamer. Simultaneous Yohkoh soft X-ray telescope (SXT) observations show increases in the filter ratios with height above the limb, indicating an increase in temperature. The application of the Aschwanden & Acton model to these SUMER data, however, show that the temperature is constant with height and that the distribution of temperatures in the corona is much too narrow for the hydrostatic weighting bias to have any effect on the SXT filter ratios. We consider the possibility that there is a tenuous hot component (~3 MK) that accounts for the SXT observations. We find that a hot plasma with an emission measure sufficient to reproduce the observed SXT fluxes would also produce significant count rates in the high-temperature emission lines in the SUMER wavelength range. These lines are not observed, and we conclude that the SUMER spectra are not consistent with the SXT filter ratio temperatures. Calculations from a hydrodynamic loop model suggest that nonuniform footpoint heating may be consistent with the temperatures and densities observed at most heights, consistent with the recent analysis of relatively cool (~1 MK) active region loops. We also find, however, that at the lowest heights the observed densities are smaller than those predicted by uniform or footpoint heating.

  5. Determination of the radial gradient in the region 0.81-1.0 AU using both high- and low-energy /more than 10-GeV and more than 52-MeV/ detectors for the 1-AU monitor. [solar quiet measurements of alpha particles and protons

    NASA Technical Reports Server (NTRS)

    Sheldon, W. R.; Bukata, R. P.; Rao, U. R.

    1974-01-01

    A determination of the radial gradient for alpha particles (31-46 MeV/nuc) and protons with energies above 7.5 MeV and 44-77 MeV in the region 1.0-0.81 AU is presented for the solar-quiet year 1966. The determinations are based on data from the Pioneer 6 space probe. Two different detectors are used: the Deep River neutron monitor and measurements of low energy protons made on the IMP-C satellite. The average energy response of the Deep River monitor is 16 GeV, whereas the IMP-C data is for protons with energies above 50 MeV. The resulting radial gradient is found to be nearly zero for the alpha particles and slightly negative for the protons. The same qualitative results were found using the IMP-C data and the Deep River neutron monitor to measure the temporal variation in the cosmic ray intensity. The present analysis indicates that detectors over a wide range of energies are suitable for measuring the radial gradient, providing sufficient statistical precision is obtained to evaluate short-term modulation and the azimuthal separation of the detectors is not great.

  6. Pain in the quiet (not red) eye.

    PubMed

    Fiore, David C; Pasternak, Andrew V; Radwan, Rabab M

    2010-07-01

    Although eye pain is often accompanied by redness or injection, pain can also occur with a quiet eye. Pain in a quiet eye can be the first sign of a vision-threatening condition, a more benign ophthalmologic condition, or a nonophthalmologic condition. Acute narrow-angle glaucoma is an emergent vision-threatening condition that requires immediate treatment and referral to an ophthalmologist. Although most nonophthalmologic conditions that cause eye pain do not need immediate treatment, giant cell (temporal) arteritis requires urgent treatment with corticosteroids. Other vascular conditions, such as carotid artery disease, thrombosis of the cavernous sinus, and transient ischemic attack or stroke, rarely cause eye pain but must be considered. Pain may also be referred from the sinuses or from neurologic conditions, such as trigeminal neuralgia, migraine and cluster headaches, and increased intracranial pressure. The differential diagnosis of eye pain in the quiet eye is extensive, necessitating a systematic and thorough approach. (c) 2010 American Academy of Family Physicians.

  7. Quiet sun magnetic fields vs. polar faculae - local vs. global dynamo?

    NASA Astrophysics Data System (ADS)

    Okunev, O. V.; Domínguez Cerdeña, I.; Puschmann, K. G.; Kneer, F.; Sánchez Almeida, J.

    2005-04-01

    Quiet Sun magnetic fields in the internetwork are almost ubiquitous. Simultaneous observations in infra-red and visible lines and high spatial resolution (< 0.5'') data in visible lines show that their field strengths range from below few hundred Gauss to kilo-Gauss. Most of the flux is contained in small-scale, strong-field features located mainly in intergranular lanes. The average unsigned flux density exceeds 20 Gauss. The new detections are confirmed by recent quiet Sun observations in the G band. The generation of the strong fields in the internetwork, which may be due to a local dynamo, poses a challenging problem. - Polar faculae (PFe) are small-scale magnetic features at the polar caps of the Sun. They take part in the solar cycle and are thus likely to be rooted deeply in the solar interior. They are the result of the global dynamo at the solar poles. PFe also possess kilo-Gauss magnetic fields which have the same polarity as the global magnetic field. The rôle of quiet Sun magnetic field structures and of PFe for the dynamics of the corona and for the solar wind are addressed.

  8. Numerical simulations of quiet Sun magnetic fields seeded by the Biermann battery

    NASA Astrophysics Data System (ADS)

    Khomenko, E.; Vitas, N.; Collados, M.; de Vicente, A.

    2017-08-01

    The magnetic fields of the quiet Sun cover at any time more than 90% of its surface and their magnetic energy budget is crucial to explain the thermal structure of the solar atmosphere. One of the possible origins of these fields is the action of the local dynamo in the upper convection zone of the Sun. Existing simulations of the local solar dynamo require an initial seed field and sufficiently high spatial resolution in order to achieve the amplification of the seed field to the observed values in the quiet Sun. Here we report an alternative model of seeding based on the action of the Bierman battery effect. This effect generates a magnetic field due to the local imbalances in electron pressure in the partially ionized solar plasma. We show that the battery effect self-consistently creates from zero an initial seed field of a strength of the order of micro G, and together with dynamo amplification allows the generation of quiet Sun magnetic fields of a similar strength to those from solar observations.

  9. MASS COMPOSITION IN PRE-ERUPTION QUIET SUN FILAMENTS

    SciTech Connect

    Kilper, Gary; Gilbert, Holly; Alexander, David

    2009-10-10

    Filament eruptions are extremely important phenomena due to their association with coronal mass ejections and their effects on space weather. Little is known about the filament mass and composition in the eruption process, since most of the related research has concentrated on the evolution and disruption of the magnetic field. Following up on our previous work, we present here an analysis of nineteen quiet Sun filament eruptions observed by Mauna Loa Solar Observatory in Halpha and He I 10830 A that has identified a compositional precursor common to all of these eruptions. There is a combined trend of an apparent increase in the homogenization of the filament mass composition, with concurrent increases in absorption in Halpha and He I and in the level of activity, all starting at least one day prior to eruption. This finding suggests that a prolonged period of mass motions, compositional mixing, and possibly even extensive mass loading is occurring during the build up of these eruptions.

  10. 76 FR 64353 - Buy Quiet Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... HUMAN SERVICES Centers for Disease Control and Prevention Buy Quiet Workshop AGENCY: National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC... Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC...

  11. 47 CFR 1.924 - Quiet zones.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... impact on the operations of radio astronomy or other facilities that are highly sensitive to interference. Consent throughout this paragraph means written consent from the quiet zone, radio astronomy, research... Radio Astronomy Observatory site located at Green Bank, Pocahontas County, West Virginia, and at the...

  12. Quiet engine program flight engine design study

    NASA Technical Reports Server (NTRS)

    Klapproth, J. F.; Neitzel, R. E.; Seeley, C. T.

    1974-01-01

    The results are presented of a preliminary flight engine design study based on the Quiet Engine Program high-bypass, low-noise turbofan engines. Engine configurations, weight, noise characteristics, and performance over a range of flight conditions typical of a subsonic transport aircraft were considered. High and low tip speed engines in various acoustically treated nacelle configurations were included.

  13. 47 CFR 1.924 - Quiet zones.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... impact on the operations of radio astronomy or other facilities that are highly sensitive to interference. Consent throughout this paragraph means written consent from the quiet zone, radio astronomy, research... Radio Astronomy Observatory site located at Green Bank, Pocahontas County, West Virginia, and at the...

  14. Radiative transfer with scattering for domain-decomposed 3D MHD simulations of cool stellar atmospheres. Numerical methods and application to the quiet, non-magnetic, surface of a solar-type star

    NASA Astrophysics Data System (ADS)

    Hayek, W.; Asplund, M.; Carlsson, M.; Trampedach, R.; Collet, R.; Gudiksen, B. V.; Hansteen, V. H.; Leenaarts, J.

    2010-07-01

    Aims: We present the implementation of a radiative transfer solver with coherent scattering in the new BIFROST code for radiative magneto-hydrodynamical (MHD) simulations of stellar surface convection. The code is fully parallelized using MPI domain decomposition, which allows for large grid sizes and improved resolution of hydrodynamical structures. We apply the code to simulate the surface granulation in a solar-type star, ignoring magnetic fields, and investigate the importance of coherent scattering for the atmospheric structure. Methods: A scattering term is added to the radiative transfer equation, requiring an iterative computation of the radiation field. We use a short-characteristics-based Gauss-Seidel acceleration scheme to compute radiative flux divergences for the energy equation. The effects of coherent scattering are tested by comparing the temperature stratification of three 3D time-dependent hydrodynamical atmosphere models of a solar-type star: without scattering, with continuum scattering only, and with both continuum and line scattering. Results: We show that continuum scattering does not have a significant impact on the photospheric temperature structure for a star like the Sun. Including scattering in line-blanketing, however, leads to a decrease of temperatures by about 350 K below log10 τ5000 ⪉ -4. The effect is opposite to that of 1D hydrostatic models in radiative equilibrium, where scattering reduces the cooling effect of strong LTE lines in the higher layers of the photosphere. Coherent line scattering also changes the temperature distribution in the high atmosphere, where we observe stronger fluctuations compared to a treatment of lines as true absorbers.

  15. QUIET-SUN INTENSITY CONTRASTS IN THE NEAR-ULTRAVIOLET AS MEASURED FROM SUNRISE

    SciTech Connect

    Hirzberger, J.; Feller, A.; Riethmueller, T. L.; Schuessler, M.; Borrero, J. M.; Gandorfer, A.; Solanki, S. K.; Barthol, P.; Afram, N.; Unruh, Y. C.; Berdyugina, S. V.; Berkefeld, T.; Schmidt, W.; Bonet, J. A.; MartInez Pillet, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    We present high-resolution images of the Sun in the near-ultraviolet spectral range between 214 nm and 397 nm as obtained from the first science flight of the 1 m SUNRISE balloon-borne solar telescope. The quiet-Sun rms intensity contrasts found in this wavelength range are among the highest values ever obtained for quiet-Sun solar surface structures-up to 32.8% at a wavelength of 214 nm. We compare the rms contrasts obtained from the observational data with theoretical intensity contrasts obtained from numerical magnetohydrodynamic simulations. For 388 nm and 312 nm the observations agree well with the numerical simulations whereas at shorter wavelengths discrepancies between observed and simulated contrasts remain.

  16. The elemental and isotopic composition of quiet time low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Smith, B.; Mcdonald, F. B.

    1983-01-01

    Isotopic abundances during several periods of solar quiet times are derived from multidimensional analysis of double dE/dX modes made with two 150 micron dE detectors and a 3000 micron stopping E detector. The spectra of the low-energy cosmic rays suggest that all the primary species of elements exhibit flux enhancements. The flux increases of 5-12 MeV/N for C, Mg, Si, and Fe are different from the anomalous components and may result from solar contamination of the quiet time data or from interplanetary acceleration processes. They may be anomalous components (ACR), although to a lesser extent than He, N, O, and Ne. The isotopic data indicate that the ACR component is predominantly N-14, O-16, and Ne-20. The isotopic compositions require that the ACRs have traversed a very limited amount of material, suggesting a local origin for them.

  17. Comparing Time-Distance Results within a Coronal Hole to the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Hess Webber, Shea A.; Pesnell, W. Dean; Duvall, Thomas, Jr.; Birch, Aaron; Cameron, Robert

    2016-10-01

    Time-distance helioseismology studies perturbations in solar wave modes. We use these techniques with SDO/HMI time distance velocity-tracked dopplergram data to investigate differences between f-mode wave propagation within a coronal hole feature and without. We use symmetry arguments to enhance the signal-to-noise ratio of the cross-correlation results. We then look for phase and amplitude discrepancies between the coronal hole and quiet sun by comparing statistically significant differences between the regions.

  18. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Quiet Zone. (iii) New Quiet Zones and New Partial Quiet Zones established along the same rail line... requirements applicable to New Quiet Zones and New Partial Quiet Zones. (iii) The deletion of any public... 49 Transportation 4 2012-10-01 2012-10-01 false What are the minimum requirements for quiet...

  19. The Hidden Gifts of Quiet Kids

    ERIC Educational Resources Information Center

    Trierweiler, Hannah

    2006-01-01

    The author relates that she was an introvert child. It has always taken her time and energy to find her place in a group. As a grown-up, she still needed quiet time to regroup during a busy day. In this article, the author presents an interview with Marti Olsen Laney, author of "The Hidden Gifts of the Introverted Child." During the interview,…

  20. Mideast stays quiet but has vigor

    SciTech Connect

    Not Available

    1985-05-01

    New drilling activity in the Middle East comes in the Egyptian Red Sea and at both Yemen and Qatar. The last in the scene of the giant North Dome gas development. Otherwise the Mideast sector is quiet with hard production ceilings demanded by OPEC and a war on the east coast of the gulf causing more confusion. A review of the current activity is presented.

  1. BUY QUIET INITIATIVE IN THE USA

    PubMed Central

    Beamer, Bryan; McCleery, Trudi; Hayden, Charles

    2016-01-01

    Noise-induced hearing loss is still considered one of the most common work-related illnesses in the United States of America. The U.S. National Institute for Occupational Safety and Health launched a national Buy Quiet campaign to raise awareness of the importance of purchasing quieter equipment. Buy Quiet encourages companies to seek out and demand quieter equipment thus driving the market to design and create quieter products. In the long run, investment in noise controls should be more prevalent as the market demands quieter products. This paradigm occurs as the market for quieter products expands both from the supply side (manufacturers) and the demand side (tool and equipment purchasers). The key to experiencing the reduced costs and increased benefits of Buy Quiet will be to develop partnerships between manufacturers and consumers. To this end, the U.S. National Institute for Occupational Safety and Health continues to work with partners to educate stakeholders about the risks and true costs of noise-induced hearing loss, as well as the economic benefits of buying quieter equipment. PMID:27274613

  2. BUY QUIET INITIATIVE IN THE USA.

    PubMed

    Beamer, Bryan; McCleery, Trudi; Hayden, Charles

    2016-04-01

    Noise-induced hearing loss is still considered one of the most common work-related illnesses in the United States of America. The U.S. National Institute for Occupational Safety and Health launched a national Buy Quiet campaign to raise awareness of the importance of purchasing quieter equipment. Buy Quiet encourages companies to seek out and demand quieter equipment thus driving the market to design and create quieter products. In the long run, investment in noise controls should be more prevalent as the market demands quieter products. This paradigm occurs as the market for quieter products expands both from the supply side (manufacturers) and the demand side (tool and equipment purchasers). The key to experiencing the reduced costs and increased benefits of Buy Quiet will be to develop partnerships between manufacturers and consumers. To this end, the U.S. National Institute for Occupational Safety and Health continues to work with partners to educate stakeholders about the risks and true costs of noise-induced hearing loss, as well as the economic benefits of buying quieter equipment.

  3. Radio-quiet Gamma-ray Pulsars

    NASA Astrophysics Data System (ADS)

    Lin, Lupin Chun-Che

    2016-09-01

    A radio-quiet γ-ray pulsar is a neutron star that has significant γ-ray pulsation but without observed radio emission or only limited emission detected by high sensitivity radio surveys. The launch of the Fermi spacecraft in 2008 opened a new epoch to study the population of these pulsars. In the 2nd Fermi Large Area Telescope catalog of γ-ray pulsars, there are 35 (30 % of the 117 pulsars in the catalog) known samples classified as radio-quiet γ-ray pulsars with radio flux density (S1400) of less than 30 μJy. Accompanying the observations obtained in various wavelengths, astronomers not only have the opportunity to study the emitting nature of radio-quiet γ-ray pulsars but also have proposed different models to explain their radiation mechanism. This article will review the history of the discovery, the emission properties, and the previous efforts to study pulsars in this population. Some particular cases known as Geminga-like pulsars (e.g., PSR J0633+1746, PSR J0007+7303, PSR J2021+4026, and so on) are also specified to discuss their common and specific features.

  4. Inference of magnetic fields in the very quiet Sun

    NASA Astrophysics Data System (ADS)

    Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.; Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.; Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.; González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.; Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman, T.; Volkmer, R.

    2016-11-01

    Context. Over the past 20 yr, the quietest areas of the solar surface have revealed a weak but extremely dynamic magnetism occurring at small scales (<500 km), which may provide an important contribution to the dynamics and energetics of the outer layers of the atmosphere. Understanding this magnetism requires the inference of physical quantities from high-sensitivity spectro-polarimetric data with high spatio-temporal resolution. Aims: We present high-precision spectro-polarimetric data with high spatial resolution (0.4'') of the very quiet Sun at 1.56 μm obtained with the GREGOR telescope to shed some light on this complex magnetism. Methods: We used inversion techniques in two main approaches. First, we assumed that the observed profiles can be reproduced with a constant magnetic field atmosphere embedded in a field-free medium. Second, we assumed that the resolution element has a substructure with either two constant magnetic atmospheres or a single magnetic atmosphere with gradients of the physical quantities along the optical depth, both coexisting with a global stray-light component. Results: Half of our observed quiet-Sun region is better explained by magnetic substructure within the resolution element. However, we cannot distinguish whether this substructure comes from gradients of the physical parameters along the line of sight or from horizontal gradients (across the surface). In these pixels, a model with two magnetic components is preferred, and we find two distinct magnetic field populations. The population with the larger filling factor has very weak ( 150 G) horizontal fields similar to those obtained in previous works. We demonstrate that the field vector of this population is not constrained by the observations, given the spatial resolution and polarimetric accuracy of our data. The topology of the other component with the smaller filling factor is constrained by the observations for field strengths above 250 G: we infer hG fields with

  5. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    SciTech Connect

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  6. Quiet-Sun Network Bright Point Phenomena with Sigmoidal Signatures

    NASA Astrophysics Data System (ADS)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  7. First Limits on the 3-200 keV X-Ray Spectrum of the Quiet Sun Using RHESSI

    NASA Astrophysics Data System (ADS)

    Hannah, I. G.; Hurford, G. J.; Hudson, H. S.; Lin, R. P.; van Bibber, K.

    2007-04-01

    We present the first results using the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) to observe solar X-ray emission not associated with active regions, sunspots, or flares (the quiet Sun). Using a newly developed chopping technique (fan-beam modulation) during seven periods of offpointing between 2005 June and 2006 October, we obtained upper limits over 3-200 keV for the quietest times when the GOES 12 1-8 Å flux fell below 10-8 W m-2. These values are smaller than previous limits in the 17-120 keV range and extend them to both lower and higher energies. The limit in 3-6 keV is consistent with a coronal temperature <=6 MK. For quiet-Sun periods when the GOES 12 1-8 Å background flux was between 10-8 and 10-7 W m-2, the RHESSI 3-6 keV flux correlates to this as a power law, with an index of 1.08+/-0.13. The power-law correlation for microflares has a steeper index of 1.29+/-0.06. We also discuss the possibility of observing quiet-Sun X-rays due to solar axions and use the RHESSI quiet-Sun limits to estimate the axion-to-photon coupling constant for two different axion emission scenarios.

  8. Low-latitude Pi2 pulsations during intervals of quiet geomagnetic conditions (Kp≤1)

    NASA Astrophysics Data System (ADS)

    Kwon, H.-J.; Kim, K.-H.; Jun, C.-W.; Takahashi, K.; Lee, D.-H.; Lee, E.; Jin, H.; Seon, J.; Park, Y.-D.; Hwang, J.

    2013-10-01

    It has been reported that Pi2 pulsations can be excited under extremely quiet geomagnetic conditions (Kp=0). However, there have been few comprehensive reports of Pi2 pulsations in such a near ground state magnetosphere. To understand the characteristics of quiet-time Pi2 pulsations, we statistically examined Pi2 events observed on the nightside between 1800 and 0600 local time at the low-latitude Bohyun (BOH, L = 1.35) station in South Korea. We chose year 2008 for analysis because geomagnetic activity was unusually low in that year. A total of 982 Pi2 events were identified when Kp≤1. About 80% of the Pi2 pulsations had a period between 110 and 300 s, which significantly differs from the conventional Pi2 period from 40 to 150 s. Comparing Pi2 periods and solar wind conditions, we found that Pi2 periods decrease with increasing solar wind speed, consistent with the result of Troitskaya (1967). The observed wave properties are discussed in terms of plasmaspheric resonance, which has been proposed for Pi2 pulsations in the inner magnetosphere. We also found that Pi2 pulsations occur quasi-periodically with a repetition period of ˜23-38 min. We will discuss what determines such a recurrence time of Pi2 pulsations under quiet geomagnetic conditions.

  9. SOHO reveals violent action on the quiet Sun

    NASA Astrophysics Data System (ADS)

    1996-05-01

    SOHO's scientists are impressed by the vigorous action that they see going on every day, because the Sun is in the very quietest phase of its eleven-year cycle of activity. To ground-based observatories it appears extremely calm just now. The early indications of SOHO's performance amply justify the creation of a sungazing spacecraft capable of observing ultraviolet emissions that are blotted out by the Earth's atmosphere. Apart from the imager, two ultraviolet spectrometers and an ultraviolet coronagraph (an imager for the outer atmosphere) are busy analysing the violent processes at a wide range of wavelengths. Between them, these instruments should cure long-lasting ignorance concerning the Sun, especially about why the atmosphere is so hot and what drives the solar wind that blows non-stop into the Solar System. Scientists from other experimental teams use SOHO to explore the Sun from its deep interior to the far reaches of the solar wind. They have watched the supposedly quiet Sun belching huge masses of gas into space. They have mapped a hole burnt by the solar wind in a breeze of gas coming from the stars. And they have detected currents of gas flowing just below the visible surface. SOHO is a project of international cooperation between the European Space Agency and NASA. The spacecraft was built in Europe and instrumented by scientists on both sides of the Atlantic. NASA launched SOHO on 2 December 1995, and also provides the ground stations and an operations centre near Washington. The first results are the more remarkable because SOHO arrived at its vantage point 1,500,000 kilometres out in space only in February, and formally completed its commissioning on 16 April. It has a long life ahead of it. All scientific instruments are working well. The luminosity oscillation imager belonging to the VIRGO experiment had trouble with its lens cover. When opened, the cover rebounded on its hinges and closed again. Commands were devised that gave a shorter impulse

  10. Magnetic Patches in Internetwork Quiet Sun

    NASA Astrophysics Data System (ADS)

    De Wijn, Alfred; Lites, B.; Berger, T.; Shine, R.; Title, A.; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Hinode Team

    2007-05-01

    We study strong flux elements in the quiet sun in the context of the nature of quiet-sun magnetism, its coupling to chromospheric, transition-region and coronal fields, and the nature of a local turbulent dynamo. Strong, kilogauss flux elements show up intermittently as small bright points in G-band and Ca II H images. Although bright points have been extensively studied in the magnetic network, internetwork magnetism has only come under scrutiny in recent years. A full spectrum of field strengths seems to be ubiquitously present in the internetwork at small spatial scales, with the stronger elements residing in intergranular lanes. De Wijn et al. (2005) found that bright points in quiet sun internetwork areas appear recurrently with varying intensity and horizontal motion within long-lived patches that outline cell patterns on mesogranular scales. They estimate that the "magnetic patches" have a mean lifetime of nine hours, much longer than granular timescales. We use multi-hour sequences of G-band and Ca II H images as well as magnetograms recorded by the Hinode satellite to follow up on their results. The larger field of view, the longer sequences, the addition of magnetograms, and the absence of atmospheric seeing allows us to better constrain the patch lifetime, to provide much improved statistics on IBP lifetime, to compare IBPs to network bright points, and to study field polarity of IBPs in patches and between nearby patches. Hinode is an international project supported by JAXA, NASA, PPARC and ESA. We are grateful to the Hinode team for all their efforts in the design, build and operation of the mission.

  11. Design of Quiet Rotorcraft Approach Trajectories

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Burley, Casey L.; Boyd, D. Douglas, Jr.; Marcolini, Michael A.

    2009-01-01

    A optimization procedure for identifying quiet rotorcraft approach trajectories is proposed and demonstrated. The procedure employs a multi-objective genetic algorithm in order to reduce noise and create approach paths that will be acceptable to pilots and passengers. The concept is demonstrated by application to two different helicopters. The optimized paths are compared with one another and to a standard 6-deg approach path. The two demonstration cases validate the optimization procedure but highlight the need for improved noise prediction techniques and for additional rotorcraft acoustic data sets.

  12. The quiet revolution of numerical weather prediction

    NASA Astrophysics Data System (ADS)

    Bauer, Peter; Thorpe, Alan; Brunet, Gilbert

    2015-09-01

    Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

  13. The quiet revolution of numerical weather prediction.

    PubMed

    Bauer, Peter; Thorpe, Alan; Brunet, Gilbert

    2015-09-03

    Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

  14. Delayed stochastic differential model for quiet standing

    NASA Astrophysics Data System (ADS)

    Yao, W.; Yu, P.; Essex, C.

    2001-02-01

    A physiological quiet standing model, described by a delayed differential equation, subject to a white noise perturbation, is proposed to study the postural control system of human beings. It has been found that the white noise destabilizes the equilibrium state, and inertia accelerates the destabilizing process, and that the position of a person is detected and processed by the person's nervous system with a delay. This paper focuses on the analysis of Hopf bifurcation and its stability in this context. Based on the analytical predictions confirmed by numerical simulations, it has been shown that the posture of a person is controlled in such a way that possible amplitude oscillations are minimized.

  15. Towards High Reynolds Number Quiet Flow in Hypersonic Tunnels

    DTIC Science & Technology

    2009-02-23

    design methodology was developed to determine the optimal shape of the supersonic nozzle to achieve laminar flow on the nozzle walls and hence quiet...fully automated optimal design methodology was developed to determine the optimal shape of the supersonic nozzle to achieve laminar flow on the... nozzle walls and maximize the length of the region of quiet flow in the test section. In the latter case, detailed time-accurate numerical simulations

  16. The 1964-1972 quiet-time spectra of protons and helium at 2-20 MeV per nucleon

    NASA Technical Reports Server (NTRS)

    Zamow, R.

    1975-01-01

    Instruments on the IMP 4 and 5 satellites are used to observe quiet-time proton and helium fluxes in the energy range from 2 to 30 MeV/nucleon and to extend the total observation period through the solar maximum to about the solar minimum (1964-1972). The nature of quiet time at low energies is discussed, selection of quiet-time periods is described, and data are presented on the fluxes during recovery from the solar maximum. The long-term time-dependence of the proton and helium spectra over solar cycle 20 is determined. The fluxes are found to vary by a factor of approximately 7, the variation is shown to be similar to the modulation of medium-energy cosmic rays, and the observed relative abundance of protons and helium is found to be closer to the medium-energy galactic rather than the average solar-flare relative abundance. A galactic origin is suggested for the low-energy quiet-time turnup, although a solar or heliospheric acceleration mechanism is not ruled out.

  17. Decreased Stress Levels in Nurses: A Benefit of Quiet Time.

    PubMed

    Riemer, Heather C; Mates, Joanna; Ryan, Linda; Schleder, Bonnie J

    2015-09-01

    The benefits of quiet time, a therapeutic method of improving the health care environment, have been evaluated in patients, but only a few studies have examined the effects of quiet time on intensive care nurses. To evaluate the effects of implementing quiet time in a medical-surgical intensive care unit on levels of light, noise, and nurses' stress. Quiet time consisted of turning down the unit lights for a designated time. Levels of light, noise, and nurses' stress were measured. Nurses' stress levels were measured by using a 100-point visual analog scale; unit noise, by using a digital sound level meter (model 407736, Extech Instruments); and unit light, by using an illumination light meter (model 615, Huygen Corporation). Measurements were obtained 30 minutes before and 30 minutes, 1 hour, and 2 hours after implementation of quiet time. Analysis of variance and comparisons of means indicated that both light levels and nurses' stress levels were significantly decreased after quiet time (both P < .001). Noise levels were also decreased after quiet time, but the decrease was not significant (P = .08). Use of quiet time resulted in decreased light levels and decreased stress levels among nurses. Quiet time is an easily performed energy-saving intervention to promote a healthy work environment. ©2015 American Association of Critical-Care Nurses.

  18. Microwave properties of a quiet sea

    NASA Technical Reports Server (NTRS)

    Stacey, J.

    1985-01-01

    The microwave flux responses of a quiet sea are observed at five microwave frequencies and with both horizontal and vertical polarizations at each frequency--a simultaneous 10 channel receiving system. The measurements are taken from Earth orbit with an articulating antenna. The 10 channel responses are taken simultaneously since they share a common articulating collector with a multifrequency feed. The plotted flux responses show: (1) the effects of the relative, on-axis-gain of the collecting aperture for each frequency; (2) the effects of polarization rotation in the output responses of the receive when the collecting aperture mechanically rotates about a feed that is fixed; (3) the difference between the flux magnitudes for the horizontal and vertical channels, at each of the five frequencies, and for each pointing position, over a 44 degree scan angle; and (4) the RMS value of the clutter--as reckoned over the interval of a full swath for each of the 10 channels. The clutter is derived from the standard error of estimate of the plotted swath response for each channel. The expected value of the background temperature is computed for each of the three quiet seas. The background temperature includes contributions from the cosmic background, the downwelling path, the sea surface, and the upwelling path.

  19. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the Chicago...

  20. Zeeman-Tomography of a Quiet Sun Region

    NASA Astrophysics Data System (ADS)

    Carroll, T. A.; Kopf, M.

    2009-06-01

    The thermodynamic and magnetic field structure of the solar photosphere is analyzed by means of a novel 3-dimensional spectropolarimetric inversion and reconstruction technique. On the basis of high-resolution, mixed-polarity magnetoconvection simulations we used an artificial neural network (ANN) model to approximate the nonlinear inverse mapping between synthesized Stokes spectra and the underlying stratification of atmospheric parameters like temperature, LOS velocity and LOS magnetic field. This approach not only allows us to incorporate more reliable physics into the inversion process, it also enables the inversion on an absolute geometrical height scale which allows the subsequent combination of individual line-of-sight stratifications to obtain a complete 3-dimensional reconstruction (tomography) of the observed area. The MHD data as well as the ANN inversion have been adopted to Hinode/SP data. For the first time we show a tomographic reconstruction of a quiet sun region observed by Hinode. The reconstructed area covers a field of approximately 12, 000 × 12, 000 km and a height range of 510 km in the photosphere. An enormous variety of small and large scale structures can be identified in the 3-D reconstruction. The low flux region (Bmag = 20 G) we analyzed exhibits several tube like structures with magnetic field strengths of some hundred Gauss. Most of these structures rapidly loose their strength with height and only a few larger structures can retain a higher field strength to the upper layers of the photosphere.

  1. Calibrations and observations with the QUIET radiotelescope

    NASA Astrophysics Data System (ADS)

    Monsalve, Raul

    The Q/U Imaging ExperimenT (QUIET) is a project aiming to measure the predicted B-mode polarization of the Cosmic Microwave Background (CMB) radiation and improve the characterization of the E-mode component. The CMB was generated 380,000 years after the Big Bang during a period known as recombination , once the universe had expanded enough to cool to a temperature of 3,600 K. This relic radiation provides crucial information about the large-scale physical conditions and processes prevailing up to and during that period. The prediction of B-mode polarization arises from cosmological models in which the universe underwent an inflationary phase that occurred 10-35 s after the Big Bang, and lasted 10-32 s. Inflation propagated original quantum fluctuations in space-time to the post-inflationary period in the form of gravitational waves, which produced ripples in space and polarization of the CMB in the form of E- and B-mode patterns. Scalar density perturbations were also propagated by the inflation but derived in the formation of E-modes only. The detection of B-mode polarization would thus provide strong support to the inflationary scenario that considers the existence of primordial gravitational waves. The expected level of this signal is ˜ 10-8 K and its measurement represents an enormous scientific and technical challenge. The QUIET telescope observed the microwave sky with two arrays of polarimeters operating at 43 and 94 GHz. It was located in the Chilean Andes and collected more than 10,000 hours of data between October 2008 and December 2010. The detector elements are based on state-of-the-art Monolithic Microwave Integrated Circuit (MMIC) technology and were designed to provide simultaneous measurements of the Q and U Stokes parameters of the sky, improving the efficiency and sensitivity of the instrument. This thesis describes the design of the QUIET telescope, the observations conducted, and the results of the data analysis. The attention

  2. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Pre-Rule Partial Quiet Zones? 222.41 Section 222.41 Transportation Other Regulations Relating to... Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51,...

  3. The "Quiet" Troubles of Low-Income Children

    ERIC Educational Resources Information Center

    Weissbourd, Richard

    2009-01-01

    Most of the troubles poor at-risk children have are not "loud" problems like disruptive behavior or gang involvement. They are "quiet." The range of these problems is vast. Hunger, dehydration, asthma, obesity, and hearing problems can all insidiously trip children up in school. Some quiet problems are psychological--depression, anxiety, the fear…

  4. Mired in the Shadows: Quiet Students in Secondary Schools

    ERIC Educational Resources Information Center

    Thompson, Greg; Bell, James

    2011-01-01

    Quiet students are a feature of the organisation of secondary schools. Using qualitative methods and Deleuzean conceptualisations of modern subjectivity, this paper explores the ways that quiet students negotiate the terrain of their school. These negotiations often seem to produce a self that is trapped rather than a subject who seizes…

  5. RESPONSE OF GRANULATION TO SMALL-SCALE BRIGHT FEATURES IN THE QUIET SUN

    SciTech Connect

    Andic, A.; Chae, J.; Goode, P. R.; Cao, W.; Ahn, K.; Yurchyshyn, V.; Abramenko, V.

    2011-04-10

    We detected 2.8 bright points (BPs) per Mm{sup 2} in the quiet Sun with the New Solar Telescope at Big Bear Solar Observatory, using the TiO 705.68 nm spectral line at an angular resolution {approx}0.''1 to obtain a 30 minute data sequence. Some BPs formed knots that were stable in time and influenced the properties of the granulation pattern around them. The observed granulation pattern within {approx}3'' of knots presents smaller granules than those observed in a normal granulation pattern, i.e., around the knots a suppressed convection is detected. Observed BPs covered {approx}5% of the solar surface and were not homogeneously distributed. BPs had an average size of 0.''22, they were detectable for 4.28 minutes on average, and had an averaged contrast of 0.1% in the deep red TiO spectral line.

  6. Preliminary Results from the QuietSpike Flight Test

    NASA Technical Reports Server (NTRS)

    Haering, Edward A., Jr.; Cliatt, Larry J., II; Howe, Don; Waithe, Kenrick

    2007-01-01

    This viewgraph presentation reviews the QuietSpike flight test results. It shows the previous tests from Nearfield probes. The presentation then reviews the approach to test the QuietSpike, and shows graphics of the positions of the test vehicles. It also shows the components of the Sonic Boom Probing Noseboom. A graph of the Pressure Over- Under-shoot (Shaped Sonic Boom Demonstration (SSBD)Data) is presented. It reviews the Shock Probing Orientations, explaining that the probing plane is always behind the tail of the QuietSpike jet. Graphs of the Shock Position Geometry (SSBD Data) and the QuietSpike signature as of the test on 12/13/06, Near-Field Probing Directly Under the QuietSpike jet, and Near-Field Probing to Side, Near-Field Probing Above and to Side. Several slides review the Computational Fluid Dynamic models, and results compared to the probe tests.

  7. Thermospheric Response to High-Latitude Energy Sources at Quiet Times

    NASA Astrophysics Data System (ADS)

    Moe, M. M.; Moe, K.

    2004-12-01

    Recent results from the CHAMP/STAR accelerometer measurements of thermospheric neutral density have brought back to our attention the existence of important energy sources at high latitudes during geomagnetically quiet times. These energy sources produce a large dayside high-latitude density bulge which is more prominent than the sub-solar density bulge. Evidence for this persistent density enhancement during quiet times has accumulated over the past 35 years. We discuss the numerous measurements of the density bulge made by accelerometers, mass spectrometers, pressure gauges, and satellite orbital decay, as well as the correlation with airglow and ionospheric observations. The energy source for this region of increased neutral density is the solar wind, after it has passed through the Earth's bow shock and magnetosphere. The region of increased density appears on the dayside of both the northern and southern hemispheres, and has a geometrical shape similar to a lunette. The central portion of the arc of the lunette coincides with the downward projection of the magnetospheric dayside cusp. Consequently, the density bulge is best described in solar-geomagnetic coordinates. The wings of the lunette extend far beyond the footprint of the dayside cusp, and are most likely energized by particles that come from other parts of the magnetosphere. The arc of the lunette is clearly displayed by airglow observations and is matched by ionospheric measurements. The corresponding neutral density bulge is much broader in geomagnetic latitude, as one might expect from the longer time constants of neutral processes. We show a Mercator projection of the global density distribution at an altitude of 400 km at 12 hours GMT as an example of the neutral density distribution produced by both the UV and corpuscular energy sources at geomagnetically quiet times.

  8. Quiet(er) marine protected areas.

    PubMed

    Williams, Rob; Erbe, Christine; Ashe, Erin; Clark, Christopher W

    2015-11-15

    A core task in endangered species conservation is identifying important habitats and managing human activities to mitigate threats. Many marine organisms, from invertebrates to fish to marine mammals, use acoustic cues to find food, avoid predators, choose mates, and navigate. Ocean noise can affect animal behavior and disrupt trophic linkages. Substantial potential exists for area-based management to reduce exposure of animals to chronic ocean noise. Incorporating noise into spatial planning (e.g., critical habitat designation or marine protected areas) may improve ecological integrity and promote ecological resilience to withstand additional stressors. Previous work identified areas with high ship noise requiring mitigation. This study introduces the concept of "opportunity sites" - important habitats that experience low ship noise. Working with existing patterns in ocean noise and animal distribution will facilitate conservation gains while minimizing societal costs, by identifying opportunities to protect important wildlife habitats that happen to be quiet.

  9. CORONAL SEISMOLOGY USING EIT WAVES: ESTIMATION OF THE CORONAL MAGNETIC FIELD STRENGTH IN THE QUIET SUN

    SciTech Connect

    West, M. J.; Zhukov, A. N.; Dolla, L.; Rodriguez, L.

    2011-04-01

    Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however, there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The fast magnetosonic wave speed is formed from two components; the Alfven speed (magnetic) and the sound speed (thermal). By making measurements of the wave speed, coronal density and temperature it is possible to calculate the quiet-Sun coronal magnetic field strength through coronal seismology. In this paper, we investigate an EIT wave observed on 2009 February 13 by the SECCHI/EUVI instruments on board the STEREO satellites. The wave epicenter was observed at disk center in the STEREO B (Behind) satellite. At this time, the STEREO satellites were separated by approximately 90 deg., and as a consequence the STEREO A (Ahead) satellite observed the wave on the solar limb. These observations allowed us to make accurate speed measurements of the wave. The background coronal density was derived through Hinode/Extreme-ultraviolet Imaging Spectrometer observations of the quiet Sun and the temperature was estimated through the narrow temperature response in the EUVI bandpasses. The density, temperature, and speed measurements allowed us to estimate the quiet-Sun coronal magnetic field strength to be approximately 0.7 {+-} 0.7 G.

  10. Some effects of quiet geomagnetic field changes upon values used for main field modeling

    USGS Publications Warehouse

    Campbell, W.H.

    1987-01-01

    The effects of three methods of data selection upon the assumed main field levels for geomagnetic observatory records used in main field modeling were investigated for a year of very low solar-terrestrial activity. The first method concerned the differences between the year's average of quiet day field values and the average of all values during the year. For H these differences were 2-3 gammas, for D they were -0.04 to -0.12???, for Z the differences were negligible. The second method of selection concerned the effects of the daytime internal Sq variations upon the daily mean values of field. The midnight field levels when the Sq currents were a minimum deviated from the daily mean levels by as much as 4-7 gammas in H and Z but were negligible for D. The third method of selection was designed to avoid the annual and semi-annual quiet level changes of field caused by the seasonal changes in the magnetosphere. Contributions from these changes were found to be as much as 4-7 gammas in quiet years and expected to be greater than 10 gammas in active years. Suggestions for improved methods of improved data selection in main field modeling are given. ?? 1987.

  11. Coronal Seismology Using EIT Waves: Estimation of the Coronal Magnetic Field Strength in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    West, M. J.; Zhukov, A. N.; Dolla, L.; Rodriguez, L.

    2011-04-01

    Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however, there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The fast magnetosonic wave speed is formed from two components; the Alfvén speed (magnetic) and the sound speed (thermal). By making measurements of the wave speed, coronal density and temperature it is possible to calculate the quiet-Sun coronal magnetic field strength through coronal seismology. In this paper, we investigate an EIT wave observed on 2009 February 13 by the SECCHI/EUVI instruments on board the STEREO satellites. The wave epicenter was observed at disk center in the STEREO B (Behind) satellite. At this time, the STEREO satellites were separated by approximately 90°, and as a consequence the STEREO A (Ahead) satellite observed the wave on the solar limb. These observations allowed us to make accurate speed measurements of the wave. The background coronal density was derived through Hinode/Extreme-ultraviolet Imaging Spectrometer observations of the quiet Sun and the temperature was estimated through the narrow temperature response in the EUVI bandpasses. The density, temperature, and speed measurements allowed us to estimate the quiet-Sun coronal magnetic field strength to be approximately 0.7 ± 0.7 G.

  12. Coronal Seismology Using EIT Waves: Estimation Of The Coronal Magnetic Field Strength In The Quiet Sun

    NASA Astrophysics Data System (ADS)

    West, Matthew; Rodriguez, Luciano; Zhukov, Andrei; Dolla, Laurent

    Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The wave speed is formed from two components; the Alfven speed (magnetic) and the sound speed (thermal). By making measurements of the wave speed, coronal density and temperature it is possible to calculate the quiet Sun coronal magnetic field strength through coronal seismology. In this work we investigate an EIT wave observed by the SECCHI/EUVI instruments on-board the STEREO satellites. The wave epicenter was observed at disk center in the STEREO B (Behind) satellite. At this time the STEREO satellites were separated by approximately 90 degrees, and as a consequence the STEREO A (Ahead) satellite observed the wave on the solar limb. These observations allowed us to make accurate speed measurements of the wave. The background coronal density was derived through Hinode/EIS observations of the quiet Sun and the temperature was estimated through the narrow temperature response in the EUVI passbands. The density, temperature and speed measurements allowed us to estimate the quiet Sun coronal magnetic field strength to be approximately 0.7 ± 0.7 G.

  13. ON THE POLARIMETRIC SIGNATURE OF EMERGING MAGNETIC LOOPS IN THE QUIET SUN

    SciTech Connect

    Viticchie, B.

    2012-03-10

    The abundance of Stokes V profiles dominated by one lobe at the locations of emergence of {Omega}-shaped magnetic loops is evaluated. The emergence events were found in Hinode Solar Optical Telescope/spectro-polarimeter time sequences of quiet-Sun regions. Such a study has the aim of confirming a prediction based on the basic geometrical and physical properties of emerging magnetic loops: Stokes V profiles dominated by one lobe are possibly the main polarimetric signature of these structures. In agreement with this prediction, 47% of the Stokes V profiles analyzed have an amplitude asymmetry |{delta}a| > 0.3, while in the quiet Sun the abundance is of about 30%. This excess with respect to the quiet Sun is found consistently for any value of the threshold on the amplitude asymmetry. Such a result proves the goodness of the physical scenarios so far proposed for the interpretation of loop emergence events and may prompt the use of Stokes V profiles dominated by one lobe as a new proxy for their identification in observations with a good spectral sampling.

  14. Flux Cancelation as the Trigger of Quiet-Region Coronal Jet Eruptions

    NASA Technical Reports Server (NTRS)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald L.

    2017-01-01

    Coronal jets are frequent magnetically channeled narrow eruptions. They occur in various solar environments: quiet regions, coronal holes and active regions. All coronal jets observed in EUV (Extreme UltraViolet) and X-ray images show a bright spire with a base brightening, also known as jet bright point (JBP). Recent studies show that coronal jets are driven by small-scale filament eruptions. Sterling et al. 2015 did extensive study of 20 polar coronal hole jets and found that X-ray jets are mainly driven by the eruption of minifilaments. What leads to these minifilament eruptions?

  15. SOHO JOP 078 - variability and properties of the quiet sun supergranular network and internetwork.

    NASA Astrophysics Data System (ADS)

    Kučera, A.; Curdt, W.; Fludra, A.; Rybák, J.; Wöhl, H.

    Study of the variability of the quiet solar atmosphere covering as large as possible range of the temperatures using both the 2D imaging and 1D spectra was the aim of SOHO JOP 78 observations. Supergranular cells were the objects of the authors' main interest. This programme is based on the cooperation of several SOHO instruments (SUMER, CDS, MDI, EIT) and TRACE. Justification of the JOP, cooperation of instruments and specially arranged measurements for the post-facto coalignment of data from different instruments are described in this paper.

  16. Day-To Variability of the Quiet-Time Equatorial Electrojet and Post-Sunset Occurrence of Equatorial Ionospheric Scintillations

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Archana; Okpala, Kingsley

    Strength of the equatorial electrojet (EEJ) derived from measurements of the horizontal component H of the geomagnetic field at an equatorial station, Tirunelveli, and a low-latitude station Alibag, outside the influence of the EEJ, on International quiet (IQ) days of the years 2001-2005, have been subjected to Principal Component Analysis to determine the principal components (PCs) that describe the variability of the quiet-time EEJ. It is found that the first three PCs together account for 94% of the variability of the EEJ observed during the IQ days of this period. PC1 itself represents about 64% of the EEJ variations, while PC2 and PC3 respectively account for 23% and 7% of the quiet-time variability of the EEJ during these years when the daily adjusted 10.7 cm solar flux, Sa, decreased from values exceeding 200 to around 100. The temporal structure of PC1 is such that it contributes only to the variability of the normal electrojet and cannot explain events such as the counter-electrojet (CEJ). A model is constructed for quiet-day PC1 scores as a function of day number and solar activity to describe a major part of the variability of the normal quiet-time EEJ. However, the CEJ and other 'abnormal' variations such as an afternoon enhancement of the EEJ, are only associated with PC2 and PC3. The quiet-day PC2 and PC3 scores obtained in this study, therefore, indicate the influence of forcing of the equatorial ionosphere from below. The day-to-day variability of the quiet-time pre-reversal enhancement of the post-sunset equatorial F region zonal electric field, which plays a crucial role in the occurrence of scintillation-producing equatorial ionospheric irregularities, is also influenced by forcing from below. In this context, occurrence of scintillations on a 251 MHz signal, transmitted from a geostationary satellite, and recorded at Tirunelveli, is studied in relation to the PC scores, which describe the variability of the EEJ, in order to identify a possible

  17. Origin and Properties of Quiet-time 0.11-1.28 MeV Nucleon-1 Heavy-ion Population near 1 au

    NASA Astrophysics Data System (ADS)

    Dayeh, M. A.; Desai, M. I.; Mason, G. M.; Ebert, R. W.; Farahat, A.

    2017-02-01

    Using measurements from the Advanced Composition Explorer/Ultra-Low Energy Isotope Spectrometer near 1 au, we surveyed the composition and spectra of heavy ions (He-through-Fe) during quiet times from 1998 January 1 to 2015 December 31 at suprathermal energies between ˜0.11 and ˜1.28 MeV nucleon-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 82% of the time. (2) The composition of the quiet-time suprathermal heavy-ion population (3He, C-through-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 (C-Fe) spectra exhibit suprathermal tails at energies of 0.11-0.32 MeV nucleon-1 with power-law spectral indices ranging from 1.40 to 2.97. Fe spectra soften (steepen, i.e., spectral index increases) smoothly with increasing energies compared with Fe, indicating a rollover behavior of Fe at higher energies (0.45-1.28 MeV nucleon-1). (4) Spectral indices of Fe and O do not appear to exhibit clear solar cycle dependence. (2) and (3) imply that during IP quiet times and at energies above ˜0.1 MeV nucleon-1, the IP medium is dominated by material from prior solar and interplanetary events. We discuss the implications of these extended observations in the context of the current understanding of the suprathermal ion population near 1 au.

  18. Quiet Clean Short Haul Experimental Engine

    NASA Image and Video Library

    1973-02-21

    Program manager Carl Ciepluch poses with a model of the Quiet Clean Short Haul Experimental Engine (QCSEE) conceived by the National Aeronautics and Space Administration (NASA) Lewis Research Center. The QCSEE engine was designed to power future short-distance transport aircraft without generating significant levels of noise or pollution and without hindering performance. The engines were designed to be utilized on aircraft operating from small airports with short runways. Lewis researchers investigated two powered-lift designs and an array of new technologies to deal with the shorter runways. Lewis contracted General Electric to design the two QCSEE engines—one with over-the-wing power-lift and one with an under-the-wing design. A scale model of the over-the-wing engine was tested in the Full Scale Tunnel at the Langley Research Center in 1975 and 1976. Lewis researchers investigated both versions in a specially-designed test stand, the Engine Noise Test Facility, on the hangar apron. The QCSEE engines met the goals set out by the NASA researchers. The aircraft industry, however, never built the short-distance transport aircraft for which the engines were intended. Different technological elements of the engine, however, were applied to some future General Electric engines.

  19. Prognostic Analysis of the Tactical Quiet Generator

    SciTech Connect

    Hively, Lee M

    2008-09-01

    The U.S. Army needs prognostic analysis of mission-critical equipment to enable condition-based maintenance before failure. ORNL has developed and patented prognostic technology that quantifies condition change from noisy, multi-channel, time-serial data. This report describes an initial application of ORNL's prognostic technology to the Army's Tactical Quiet Generator (TQG), which is designed to operate continuously at 10 kW. Less-than-full power operation causes unburned fuel to accumulate on internal components, thereby degrading operation and eventually leading to failure. The first objective of this work was identification of easily-acquired, process-indicative data. Two types of appropriate data were identified, namely output-electrical current and voltage, plus tri-axial acceleration (vibration). The second objective of this work was data quality analysis to avoid the garbage-in-garbage-out syndrome. Quality analysis identified more than 10% of the current data as having consecutive values that are constant, or that saturate at an extreme value. Consequently, the electrical data were not analyzed further. The third objective was condition-change analysis to indicate operational stress under non-ideal operation and machine degradation in proportion to the operational stress. Application of ORNL's novel phase-space dissimilarity measures to the vibration power quantified the rising operational stress in direct proportion to the less-than-full-load power. We conclude that ORNL's technology is an excellent candidate to meet the U.S. Army's need for equipment prognostication.

  20. Nature of the Jurassic Magnetic Quiet Zone

    NASA Astrophysics Data System (ADS)

    Tominaga, Masako; Tivey, Maurice A.; Sager, William W.

    2015-10-01

    The nature of the Jurassic Quiet Zone (JQZ), a region of low-amplitude oceanic magnetic anomalies, has been a long-standing debate with implications for the history and behavior of the Earth's geomagnetic field and plate tectonics. To understand the origin of the JQZ, we studied high-resolution sea surface magnetic anomalies from the Hawaiian magnetic lineations and correlated them with the Japanese magnetic lineations. The comparison shows the following: (i) excellent correlation of anomaly shapes from M29 to M42; (ii) remarkable similarity of anomaly amplitude envelope, which decreases back in time from M19 to M38, with a minimum at M41, then increases back in time from M42; and (iii) refined locations of pre-M25 lineations in the Hawaiian lineation set. Based on these correlations, our study presents evidence of regionally and possibly globally coherent pre-M29 magnetic anomalies in the JQZ and a robust extension of Hawaiian isochrons back to M42 in the Pacific crust.

  1. Quiet swimming at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Andersen, Anders; Wadhwa, Navish; Kiørboe, Thomas

    2015-04-01

    The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world.

  2. Overview of the Arizona Quiet Pavement Program

    NASA Astrophysics Data System (ADS)

    Donavan, Paul; Scofield, Larry

    2005-09-01

    The Arizona Quiet Pavement Pilot Program (QP3) was initially implemented to reduce highway related traffic noise by overlaying most of the Phoenix metropolitan area Portland cement concrete pavement with a one inch thick asphalt rubber friction coarse. With FHWA support, this program represents the first time that pavement surface type has been allowed as a noise mitigation strategy on federally funded projects. As a condition of using pavement type as a noise mitigation strategy, ADOT developed a ten-year, $3.8 million research program to evaluate the noise reduction performance over time. Historically, pavement surface type was not considered a permanent solution. As a result, the research program was designed to specifically address this issue. Noise performance is being evaluated through three means: (1) conventional roadside testing within the roadway corridor (e.g., far field measurements within the right-of-way) (2) the use of near field measurements, both close proximity (CPX) and sound intensity (SI); and (3) far field measurements obtained beyond the noise barriers within the surrounding neighborhoods. This paper provides an overview of the program development, presents the research conducted to support the decision to overlay the urban freeway, and the status of current research.

  3. QUIET: The Q/U Imaging ExperimenT

    NASA Astrophysics Data System (ADS)

    Newburgh, Laura; QUIET Collaboration

    2010-01-01

    The Q/U Imaging Experiment (QUIET) is a ground-based CMB polarization experiment based on correlation polarimertry using high electron mobility transistor (HEMT) amplifiers. QUIET is designed to measure the CMB polarization on angular scales where the spectrum from inflationary gravity waves is predicted to be maximal. QUIET operates at two frequency bands centered at 40 GHz and 90 GHz. The 40 GHz receiver was deployed in 2008 at 5100m altitude in the Atacama Desert, Chile, and has finished data collection, logging over 3500 hours on the sky and covering 1200 square degrees. The 90 GHz receiver was deployed on the same telescope and started taking data in July 2009. I will present an instrument overview and the status of data analysis from the 40 GHz season. QUIET is supported by NSF grants AST-04-49809 and AST-05-06648.

  4. NASA F-15B #836 landing with Quiet Spike attached

    NASA Image and Video Library

    2006-10-03

    NASA F-15B #836 landing with Quiet Spike attached. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

  5. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    A study of quiet turbofan short takeoff aircraft for short haul air transportation was conducted. The objectives of the study were to: (1) define representative aircraft configurations, characteristics, and costs associated with their development, (2) identify critical technology and technology related problems to be resolved in successful introduction of representative short haul aircraft, (3) determine relationships between quiet short takeoff aircraft and the economic and social viability of short haul, and (4) identify high payoff technology areas.

  6. 49 CFR 222.39 - How is a quiet zone established?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Quiet Zone Risk Index is at, or below, the Nationwide Significant Risk Threshold, as follows: (i) If the Quiet Zone Risk Index is already at, or below, the Nationwide Significant Risk Threshold without being... Quiet Zone Risk Index to a level at, or below, the Nationwide Significant Risk Threshold. (3) A quiet...

  7. Two-Component Fitting of Coronal-Hole and Quiet-Sun He I 1083 Spectra

    NASA Technical Reports Server (NTRS)

    Jones, Harrison P.; Malanushenko, Elena V.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present reduction techniques and first results for detailed fitting of solar spectra obtained with the NASA/National Solar Observatory Spectromagnetograph (NASA/NSO SPM over a 2 nm bandpass centered on the He 1 1083 nm line. The observation for this analysis was a spectra-spectroheliogram obtained at the NSO/Kitt Peak Vacuum Telescope (KPVT) on 00 Apr 17 at 21:46 UT spanning an area of 512 x 900 arc-seconds; the field of view included a coronal hole near disk center as well as surrounding quiet sun. Since the He I line is very weak and blended with nearby solar and telluric lines, accurate determination of the continuum intensity as a function of wavelength is crucial. We have modified the technique of Malanushenko {\\it et al.) (1992; {\\it AA) (\\bf 259), 567) to tie regions of continuua and the wings of spectral lines which show little variation over the image to standard reference spectra such as the NSO Fourier Transform Spectrometer atlas (Wallace {\\it et al). 1993; NSO Tech Report \\#93-001). We performed detailed least-squares fits of spectra from selected areas, accounting for all the known telluric and solar absorbers in the spectral bandpass. The best physically consistent fits to the Helium lines were obtained with Gaussian profiles from two components (one ''cool'', characteristic of the upper chromosphere; one ''hot'', representing the cool transition region at 2-3 x 10$^{4)$ K). In the coronal hole, the transition-region component, shifted by 6-7 km/s to the blue, is mildly dominant, consistent with mass outflow as suggested by Dupree {\\it et all. (1996; {\\it Ap. J.}-{\\bf 467), 121). In quiet-sun spectra there is less evidence of outward flow, and the chromospheric component is more important. All our fitted spectra show a very weak unidentified absorption feature at 1082.880 nm in the red wing of the nearby Si I line.

  8. Observations of an Energetically Isolated Quiet Sun Transient: Evidence of Quasi-steady Coronal Heating

    NASA Astrophysics Data System (ADS)

    Orange, N. Brice; Chesny, David L.; Oluseyi, Hakeem M.

    2015-09-01

    Increasing evidence for coronal heating contributions from cooler solar atmospheric layers, notably quiet Sun (QS) conditions, challenges standard solar atmospheric descriptions of bright transition region (TR) emission. As such, questions about the role of dynamic QS transients in contributing to the total coronal energy budget are raised. Using observations from the Atmospheric Imaging Assembly and Heliosemic Magnetic Imager on board the Solar Dynamics Observatory, and numerical model extrapolations of coronal magnetic fields, we investigate a dynamic QS transient that is energetically isolated to the TR and extrudes from a common footpoint shared with two heated loop arcades. A non-causal relationship is established between episodic heating of the QS transient and widespread magnetic field re-organization events, while evidence is found favoring a magnetic topology that is typical of eruptive processes. Quasi-steady interchange reconnection events are implicated as a source of the transient’s visibly bright radiative signature. We consider the QS transient’s temporally stable (≈35 minutes) radiative nature to occur as a result of the large-scale magnetic field geometries of the QS and/or relatively quiet nature of the magnetic photosphere, which possibly act to inhibit energetic build-up processes that are required to initiate a catastrophic eruption phase. This work provides insight into the QS’s thermodynamic and magnetic relation to eruptive processes that quasi-steadily heat a small-scale dynamic and TR transient. This work explores arguments of non-negligible coronal heating contributions from cool atmospheric layers in QS conditions and contributes evidence to the notion that solar wind mass feeds off of dynamic transients therein.

  9. OBSERVATIONS OF AN ENERGETICALLY ISOLATED QUIET SUN TRANSIENT: EVIDENCE OF QUASI-STEADY CORONAL HEATING

    SciTech Connect

    Orange, N. Brice; Chesny, David L.; Oluseyi, Hakeem M.

    2015-09-10

    Increasing evidence for coronal heating contributions from cooler solar atmospheric layers, notably quiet Sun (QS) conditions, challenges standard solar atmospheric descriptions of bright transition region (TR) emission. As such, questions about the role of dynamic QS transients in contributing to the total coronal energy budget are raised. Using observations from the Atmospheric Imaging Assembly and Heliosemic Magnetic Imager on board the Solar Dynamics Observatory, and numerical model extrapolations of coronal magnetic fields, we investigate a dynamic QS transient that is energetically isolated to the TR and extrudes from a common footpoint shared with two heated loop arcades. A non-causal relationship is established between episodic heating of the QS transient and widespread magnetic field re-organization events, while evidence is found favoring a magnetic topology that is typical of eruptive processes. Quasi-steady interchange reconnection events are implicated as a source of the transient’s visibly bright radiative signature. We consider the QS transient’s temporally stable (≈35 minutes) radiative nature to occur as a result of the large-scale magnetic field geometries of the QS and/or relatively quiet nature of the magnetic photosphere, which possibly act to inhibit energetic build-up processes that are required to initiate a catastrophic eruption phase. This work provides insight into the QS’s thermodynamic and magnetic relation to eruptive processes that quasi-steadily heat a small-scale dynamic and TR transient. This work explores arguments of non-negligible coronal heating contributions from cool atmospheric layers in QS conditions and contributes evidence to the notion that  solar wind mass feeds off of dynamic transients therein.

  10. A quiet ego quiets death anxiety: humility as an existential anxiety buffer.

    PubMed

    Kesebir, Pelin

    2014-04-01

    Five studies tested the hypothesis that a quiet ego, as exemplified by humility, would buffer death anxiety. Humility is characterized by a willingness to accept the self and life without comforting illusions, and by low levels of self-focus. As a consequence, it was expected to render mortality thoughts less threatening and less likely to evoke potentially destructive behavior patterns. In line with this reasoning, Study 1 found that people high in humility do not engage in self-serving moral disengagement following mortality reminders, whereas people low in humility do. Study 2 showed that only people low in humility respond to death reminders with increased fear of death, and established that this effect was driven uniquely by humility and not by some other related personality trait. In Study 3, a low sense of psychological entitlement decreased cultural worldview defense in response to death thoughts, whereas a high sense of entitlement tended to increase it. Study 4 demonstrated that priming humility reduces self-reported death anxiety relative to both a baseline and a pride priming condition. Finally, in Study 5, experimentally induced feelings of humility prevented mortality reminders from leading to depleted self-control. As a whole, these findings obtained from relatively diverse Internet samples illustrate that the dark side of death anxiety is brought about by a noisy ego only and not by a quiet ego, revealing self-transcendence as a sturdier, healthier anxiety buffer than self-enhancement. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  11. Refining the Jurassic Magnetic Quiet Zone

    NASA Astrophysics Data System (ADS)

    Tominaga, M.; Tivery, M.; Sager, W. W.

    2016-12-01

    We present a coherent marine magnetic reversal record from the Pacific to refine the Jurassic Quiet Zone (JQZ). Our definitive magnetic anomaly record consists of high-resolution sea surface, mid-water (3-km level deep-towed), and near-bottom profiles (0.1-km to the seafloor) with the magnetic source layer constrained by gravity anomaly data and reflection and refraction seismics, all of which are newly collected during TN272 and SKQ2014S2 cruises. All magnetic anomaly data were corrected diurnal variations and the present-day ambient geomagnetic field. In comparing our three-level JQZ magnetic anomaly profiles with previous work in the Japanese lineations, we confirm a globally coherent anomaly sequence in the JQZ from M29 to M42, including the distinctive amplitude envelope decreasing back in time from M19 to M38, with a minimum at M41, and then increasing back in time. A strong similarity in the M37/M38 polarity attributes found both in magnetostratigraphic and marine magnetic records suggest that rapid magnetic reversals were occurring during the M38 time in the JQZ. Seismic and gravity profiles from the Hawaiian JQZ seafloor show late-stage Cretaceous volcanism thickening crust by up to 150% with extra melt emplaced at the Moho, and numerous sills and volcanic cones in the sediment and on the seafloor. The region of thickest crust in the Hawaiian lineation corridor coincides with the region of the lowest JQZ anomaly amplitudes, very similar to the Low Amplitude Zone of Japanese lineation sequence, suggesting that the JQZ anomaly character can represent changes in geomagnetic field intensity over time but is free of the effects of Cretaceous volcanic overprint. We conducted inversion modeling to establish polarity block models and to estimate reversal rates. Reversal rates are the highest during periods with the lowest anomaly amplitudes, indicating a unique period of geomagnetic field behavior in the Earth's history.

  12. Sonic Inlet for the Quiet Engine Program

    NASA Image and Video Library

    1974-01-21

    Brent Miller, of the V/STOL and Noise Division at the National Aeronautics and Space Administration (NASA) Lewis Research Center, poses with a sonic inlet for the NASA Quiet Engine Program. NASA Lewis had first investigated methods for reducing aircraft engine noise in the mid-1950s. Those efforts were resurrected and expanded in the late 1960s. The researchers found that the use of a sonic, or high-throat-Mach-number, inlet was effective at reducing the noise from the engine inlet. The device accelerated the inlet air to near-sonic speeds which kept the forward moving sound waves away from the inlet. The device also deflected the sound waves into the wall to further reduce the noise. NASA Lewis researchers tested models of the sonic inlet in their 9- by 15-Foot Low Speed Wind Tunnel. They found that the general level of aerodynamic performance was good. The tests during simulated takeoff and landing conditions demonstrated the sonic inlet’s ability to provide good aerodynamic and acoustic performance The researchers then successfully tested two full-scale sonic inlet designs, one from Pratt and Whitney and one from General Electric, with fans. A full-scale engine was installed on a thrust stand to determine the sonic inlet’s effect on the engine’s performance. The amount of noise reduction increased as the inlet flow velocity increased, but the full-scale tests did not produce as great a decrease in noise as the earlier small-scale tests.

  13. First simultaneous SST/CRISP and IRIS observations of a small-scale quiet Sun vortex

    NASA Astrophysics Data System (ADS)

    Park, S.-H.; Tsiropoula, G.; Kontogiannis, I.; Tziotziou, K.; Scullion, E.; Doyle, J. G.

    2016-02-01

    Context. Ubiquitous small-scale vortices have recently been found in the lower atmosphere of the quiet Sun in state-of-the-art solar observations and in numerical simulations. Aims: We investigate the characteristics and temporal evolution of a granular-scale vortex and its associated upflows through the photosphere and chromosphere of a quiet Sun internetwork region. Methods: We analyzed high spatial and temporal resolution ground- and spaced-based observations of a quiet Sun region. The observations consist of high-cadence time series of wideband and narrowband images of both Hα 6563 Å and Ca II 8542 Å lines obtained with the CRisp Imaging SpectroPolarimeter (CRISP) instrument at the Swedish 1-m Solar Telescope (SST), as well as ultraviolet imaging and spectral data simultaneously obtained by the Interface Region Imaging Spectrograph (IRIS). Results: A small-scale vortex is observed for the first time simultaneously in Hα, Ca II 8542 Å, and Mg II k lines. During the evolution of the vortex, Hα narrowband images at -0.77 Å and Ca II 8542 Å narrowband images at -0.5 Å, and their corresponding Doppler signal maps, clearly show consecutive high-speed upflow events in the vortex region. These high-speed upflows with a size of 0.5-1 Mm appear in the shape of spiral arms and exhibit two distinctive apparent motions in the plane of sky for a few minutes: (1) a swirling motion with an average speed of 13 km s-1 and (2) an expanding motion at a rate of 4-6 km s-1. Furthermore, the spectral analysis of Mg II k and Mg II subordinate lines in the vortex region indicates an upward velocity of up to ~8 km s-1 along with a higher temperature compared to the nearby quiet Sun chromosphere. Conclusions: The consecutive small-scale vortex events can heat the upper chromosphere by driving continuous high-speed upflows through the lower atmosphere. Movies associated to Figs. 2 and 3 are available at http://www.aanda.org

  14. The quiet-Sun photosphere and chromosphere.

    PubMed

    Rutten, Robert J

    2012-07-13

    The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly the important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top and small-scale vorticity. Classical one-dimensional static radiation-escape modelling has been replaced by three-dimensional time-dependent magento-hydrodynamic simulations that come closer to reality. The solar chromosphere, in contrast, remains little understood, although its pivotal role in coronal mass and energy loading makes it a principal research area. Its fine structure defines its overall structure, so that hard-to-observe and hard-to-model small-scale dynamical processes are key to understanding. However, both chromospheric observation and chromospheric simulation presently mature towards the required sophistication. Open-field features seem of greater interest than easier-to-see closed-field features.

  15. HOMOLOGOUS CYCLONES IN THE QUIET SUN

    SciTech Connect

    Yu, Xinting; Zhang, Jun; Li, Ting; Zhang, Yuzong; Yang, Shuhong E-mail: zjun@nao.cas.cn E-mail: yuzong@nao.cas.cn

    2014-02-20

    Through observations with the Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager, we tracked one rotating network magnetic field (RNF) near the solar equator. It lasted for more than 100 hr, from 2013 February 23 to 28. During its evolution, three cyclones were found to be rooted in this structure. Each cyclone event lasted for about 8 to 10 hr. While near the polar region, another RNF was investigated. It lasted for a shorter time (∼70 hr), from 2013 July 7 to 9. There were two cyclones rooted in the RNF and each lasted for 8 and 11 hr, respectively. For the two given examples, the cyclones have a similar dynamic evolution, and thus we put forward a new term: homologous cyclones. The detected brightening in AIA 171 Å maps indicates the release of energy, which is potentially available to heat the corona.

  16. A New Observation of the Quiet Sun Soft X-ray (0.5-5 keV) Spectrum

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Woods, T. N.; Stone, J.

    2012-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable with solar activity. While this is particularly true during solar flares, when emission can be enhanced by many orders of magnitude up to gamma-ray energies, even the so-called "quiet Sun" is bright in soft X-rays (SXRs), as the ~1-2 MK ambient plasma of the corona emits significant thermal bremsstrahlung up to ~5 keV. However, the actual solar SXR (0.5-5 keV) spectrum is not well known, particularly during quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include ultra-high-resolution but very narrow-band spectra from crystral spectrometers (e.g. Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g. GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with fair energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and XRS on MESSENGER, although they did not extend below ~1 keV. We present observations of the quiet Sun SXR emission obtained using a new SXR spectrometer flown on the third SDO/EVE underflight calibration rocket (NASA 36.286). The commercial off-the-shelf Amptek X123 silicon drift detector, with an 8-micron Be window and custom aperture, measured the solar SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution (though, due to hardware limitations, with only ~0.12 keV binning) and 2-sec cadence over ~5 minutes on 23 June 2012. Despite the rising solar cycle, activity on 23 June 2012 was abnormally low, with no visible active regions and GOES XRS emission near 2010 levels; we measured no solar counts above ~4 keV during the observation period. We compare our X123 measurements with spectra and broadband irradiances from other instruments, including the SphinX observations during the deep solar minimum of 2009, and with upper limits of >3 keV quiet Sun emission

  17. Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity

    NASA Astrophysics Data System (ADS)

    Lagg, A.; Solanki, S. K.; Doerr, H.-P.; Martínez González, M. J.; Riethmüller, T.; Collados Vera, M.; Schlichenmaier, R.; Orozco Suárez, D.; Franz, M.; Feller, A.; Kuckein, C.; Schmidt, W.; Asensio Ramos, A.; Pastor Yabar, A.; von der Lühe, O.; Denker, C.; Balthasar, H.; Volkmer, R.; Staude, J.; Hofmann, A.; Strassmeier, K.; Kneer, F.; Waldmann, T.; Borrero, J. M.; Sobotka, M.; Verma, M.; Louis, R. E.; Rezaei, R.; Soltau, D.; Berkefeld, T.; Sigwarth, M.; Schmidt, D.; Kiess, C.; Nicklas, H.

    2016-11-01

    Context. Investigations of the magnetism of the quiet Sun are hindered by extremely weak polarization signals in Fraunhofer spectral lines. Photon noise, straylight, and the systematically different sensitivity of the Zeeman effect to longitudinal and transversal magnetic fields result in controversial results in terms of the strength and angular distribution of the magnetic field vector. Aims: The information content of Stokes measurements close to the diffraction limit of the 1.5 m GREGOR telescope is analyzed. We took the effects of spatial straylight and photon noise into account. Methods: Highly sensitive full Stokes measurements of a quiet-Sun region at disk center in the deep photospheric Fe i lines in the 1.56 μm region were obtained with the infrared spectropolarimeter GRIS at the GREGOR telescope. Noise statistics and Stokes V asymmetries were analyzed and compared to a similar data set of the Hinode spectropolarimeter (SOT/SP). Simple diagnostics based directly on the shape and strength of the profiles were applied to the GRIS data. We made use of the magnetic line ratio technique, which was tested against realistic magneto-hydrodynamic simulations (MURaM). Results: About 80% of the GRIS spectra of a very quiet solar region show polarimetric signals above a 3σ level. Area and amplitude asymmetries agree well with small-scale surface dynamo-magneto hydrodynamic simulations. The magnetic line ratio analysis reveals ubiquitous magnetic regions in the ten to hundred Gauss range with some concentrations of kilo-Gauss fields. Conclusions: The GRIS spectropolarimetric data at a spatial resolution of ≈0.̋4 are so far unique in the combination of high spatial resolution scans and high magnetic field sensitivity. Nevertheless, the unavoidable effect of spatial straylight and the resulting dilution of the weak Stokes profiles means that inversion techniques still bear a high risk of misinterpretating the data.

  18. IRIS Burst Spectra Co-spatial to a Quiet-Sun Ellerman-like Brightening

    NASA Astrophysics Data System (ADS)

    Nelson, C. J.; Freij, N.; Reid, A.; Oliver, R.; Mathioudakis, M.; Erdélyi, R.

    2017-08-01

    Ellerman bombs (EBs) have been widely studied over the past two decades; however, only recently have the counterparts of these events been observed in the quiet-Sun. The aim of this article is to further understand small-scale quiet-Sun Ellerman-like brightenings (QSEBs) through research into their spectral signatures, including investigating whether the hot signatures associated with some EBs are also visible co-spatial to any QSEBs. We combine Hα and Ca ii 8542 Å line scans at the solar limb with spectral and imaging data sampled by the Interface Region Imaging Spectrograph (IRIS). Twenty-one QSEBs were identified with average lifetimes, lengths, and widths measured to be around 120 s, 0.″63, and 0.″35, respectively. Three of these QSEBs displayed clear repetitive flaring through their lifetimes, comparable to the behavior of EBs in active regions. Two QSEBs in this sample occurred co-spatial to increased emission in SDO/AIA 1600 Å and IRIS slit-jaw imager 1400 Å data; however, these intensity increases were smaller than those reported co-spatially with EBs. One QSEB was also sampled by the IRIS slit during its lifetime, displaying increases in intensity in the Si iv 1393 Å and Si iv 1403 Å cores, as well as the C ii and Mg ii line wings, analogous to IRIS bursts (IBs). Using RADYN simulations, we are unable to reproduce the observed QSEB Hα and Ca ii 8542 Å line profiles, leaving the question of the temperature stratification of QSEBs open. Our results imply that some QSEBs could be heated to transition region temperatures, suggesting that IB profiles should be observed throughout the quiet-Sun.

  19. Field Line Resonances in Quiet and Disturbed Time Three-dimensional Magnetospheres

    SciTech Connect

    C.Z. Cheng; S. Zaharia

    2002-05-30

    Numerical solutions for field line resonances (FLR) in the magnetosphere are presented for three-dimensional equilibrium magnetic fields represented by two Euler potentials as B = -j Y -a, where j is the poloidal flux and a is a toroidal angle-like variable. The linearized ideal-MHD equations for FLR harmonics of shear Alfvin waves and slow magnetosonic modes are solved for plasmas with the pressure assumed to be isotropic and constant along a field line. The coupling between the shear Alfvin waves and the slow magnetosonic waves is via the combined effects of geodesic magnetic field curvature and plasma pressure. Numerical solutions of the FLR equations are obtained for a quiet time magnetosphere as well as a disturbed time magnetosphere with a thin current sheet in the near-Earth region. The FLR frequency spectra in the equatorial plane as well as in the auroral latitude are presented. The field line length, magnetic field intensity, plasma beta, geodesic curvature and pressure gradient in the poloidal flux surface are important in determining the FLR frequencies. In general, the computed shear Alfvin FLR frequency based on the full MHD model is larger than that based on the commonly adopted cold plasma model in the beq > 1 region. For the quiet time magnetosphere, the shear Alfvin resonance frequency decreases monotonically with the equatorial field line distance, which reasonably explains the harmonically structured continuous spectrum of the azimuthal magnetic field oscillations as a function of L shell in the L is less than or equal to 9RE region. However, the FLR frequency spectrum for the disturbed time magnetosphere with a near-Earth thin current sheet is substantially different from that for the quiet time magnetosphere for R > 6RE, mainly due to shorter field line length due to magnetic field compression by solar wind, reduced magnetic field intensity in the high-beta current sheet region, azimuthal pressure gradient, and geodesic magnetic field

  20. A novel acoustically quiet coil for neonatal MRI system.

    PubMed

    Ireland, Christopher M; Giaquinto, Randy O; Loew, Wolfgang; Tkach, Jean A; Pratt, Ronald G; Kline-Fath, Beth M; Merhar, Stephanie L; Dumoulin, Charles L

    2015-08-01

    MRI acoustic exposure has the potential to elicit physiological distress and impact development in preterm and term infants. To mitigate this risk, a novel acoustically quiet coil was developed to reduce the sound pressure level experienced by neonates during MR procedures. The new coil has a conventional high-pass birdcage RF design, but is built on a framework of sound abating material. We evaluated the acoustic and MR imaging performance of the quiet coil and a conventional body coil on two small footprint NICU MRI systems. Sound pressure level and frequency response measurements were made for six standard clinical MR imaging protocols. The average sound pressure level, reported for all six imaging pulse sequences, was 82.2 dBA for the acoustically quiet coil, and 91.1 dBA for the conventional body coil. The sound pressure level values measured for the acoustically quiet coil were consistently lower, 9 dBA (range 6-10 dBA) quieter on average. The acoustic frequency response of the two coils showed a similar harmonic profile for all imaging sequences. However, the amplitude was lower for the quiet coil, by as much as 20 dBA.

  1. A novel acoustically quiet coil for neonatal MRI system

    PubMed Central

    Ireland, Christopher M.; Giaquinto, Randy O.; Loew, Wolfgang; Tkach, Jean A.; Pratt, Ronald G.; Kline-Fath, Beth M.; Merhar, Stephanie L.; Dumoulin, Charles L.

    2015-01-01

    MRI acoustic exposure has the potential to elicit physiological distress and impact development in preterm and term infants. To mitigate this risk, a novel acoustically quiet coil was developed to reduce the sound pressure level experienced by neonates during MR procedures. The new coil has a conventional high-pass birdcage RF design, but is built on a framework of sound abating material. We evaluated the acoustic and MR imaging performance of the quiet coil and a conventional body coil on two small footprint NICU MRI systems. Sound pressure level and frequency response measurements were made for six standard clinical MR imaging protocols. The average sound pressure level, reported for all six imaging pulse sequences, was 82.2 dBA for the acoustically quiet coil, and 91.1 dBA for the conventional body coil. The sound pressure level values measured for the acoustically quiet coil were consistently lower, 9 dBA (range 6-10 dBA) quieter on average. The acoustic frequency response of the two coils showed a similar harmonic profile for all imaging sequences. However, the amplitude was lower for the quiet coil, by as much as 20 dBA. PMID:26457072

  2. STUDY OF SINGLE-LOBED CIRCULAR POLARIZATION PROFILES IN THE QUIET SUN

    SciTech Connect

    Sainz Dalda, A.; Martinez-Sykora, J.; Title, A.; Bellot Rubio, L. E-mail: asainz@lmsal.com

    2012-03-20

    The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere has been known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight (LOS), possibly associated with gradients of magnetic field strength, inclination, and/or azimuth. We have focused our study on the Stokes V profiles showing extreme asymmetry in the form of only one lobe. Using Hinode spectropolarimetric measurements, we have performed a statistical study of the properties of these profiles in the quiet Sun. We show their spatial distribution, their main physical properties, how they are related with several physical observables, and their behavior with respect to their position on the solar disk. The single-lobed Stokes V profiles occupy roughly 2% of the solar surface. For the first time, we have observed their temporal evolution and have retrieved the physical conditions of the atmospheres from which they emerged using an inversion code implementing discontinuities of the atmospheric parameters along the LOS. In addition, we use synthetic Stokes profiles from three-dimensional magnetoconvection simulations to complement the results of the inversion. The main features of the synthetic single-lobed profiles are in general agreement with the observed ones, lending support to the magnetic and dynamic topologies inferred from the inversion. The combination of all these different analyses suggests that most of the single-lobed Stokes V profiles are signals coming from the magnetic flux emergence and/or submergence processes taking place in small patches in the photosphere of the quiet Sun.

  3. Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Király, Péter

    Energetic particles recorded in the Earth environment and in interplanetary space have a multitude of origins, i.e. acceleration and propagation histories. At early days practically all sufficiently energetic particles were considered to have come either from solar flares or from interstellar space. Later on, co-rotating interplanetary shocks, the termination shock of the supersonic solar wind, planetary bow shocks and magnetospheres, and also coronal mass ejections (CME) were recognized as energetic particle sources. It was also recognized that less energetic (suprathermal) particles of solar origin and pick-up ions have also a vital role in giving rise to energetic particles in interplanetary disturbances. The meaning of the term "solar energetic particles" (SEP) is now somewhat vague, but essentially it refers to particles produced in disturbances fairly directly related to solar processes. Variation of intensity fluctuations with energy and with the phase of the solar cycle will be discussed. Particular attention will be given to extremes of time variation, i.e. to very quiet periods and to large events. While quiet-time fluxes are expected to shed light on some basic coronal processes, large events dominate the fluctuation characteristics of cumulated fluence, and the change of that fluctuation with energy and with the phase of the solar cycle may also provide important clues. Mainly ISEE-3 and long-term IMP-8 data will be invoked. Energetic and suprathermal particles that may never escape into interplanetary space may play an important part in heating the corona of the sun.

  4. The global modulation of cosmic rays during a quiet heliosphere: A modeling perspective

    NASA Astrophysics Data System (ADS)

    Potgieter, M. S.

    2017-08-01

    A perspective is given of the solar modulation of galactic cosmic rays in the heliosphere during the extraordinary quiet solar minimum period from 2006 to 2009. This is done in the context of the total modulation of cosmic rays in a global heliosphere. Such an approach has become possible since the observation of galactic cosmic rays made beyond the heliopause by Voyager 1 so that together with very precise observations at higher energies at the Earth, more reliable local interstellar spectra can be established. Combined with the results from comprehensive modeling, a global view unfolds. The requirements for such an approach to the modeling of solar modulation are discussed. Computed, modulated spectra for protons and electrons are shown, for 2006-2009 together with computed radial and latitudinal gradients for protons, in comparison with observations where available. Predictions are made for the energy ranges not covered by the 2006-2009 observations. Respectively, the modulation factor for protons, electrons and positrons are given for energies as low as 5 MeV for the mentioned period. The computed electron to positron ratio is presented as applicable to solar minimum modulation conditions. The differences in the modulation of protons, electrons and positrons are illustrated for such conditions and the main contributions to this global process, including particle drifts, are discussed.

  5. Quiet-sun and non-flaring active region measurements from the FOXSI-2 sounding rocket

    NASA Astrophysics Data System (ADS)

    Buitrago-Casas, J. C.; Glesener, L.; Christe, S.; Ishikawa, S. N.; Narukage, N.; Krucker, S.; Bale, S. D.

    2016-12-01

    Solar hard X-ray (HXR) emissions are a cornerstone for understanding particle acceleration and energy release in the corona. These phenomena are present at different size scales and intensities, from large eruptive events down to the smallest flares. The presence of HXRs in small, unresolved flares would provide direct evidence of small reconnection events, i.e. nano-flares, that are thought to be be important for the unsolved coronal heating problem. Currently operating solar-dedicated instruments that observe HXRs from the Sun do not have the dynamic range, nor the sensitivity, crucial to observe the faintest solar HXRs. The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload is a novel experiment that develops and applies direct focusing optics coupled with semiconductor detectors to observe faint HXRs from the Sun. The FOXSI rocket has successfully completed two flights, observing areas of the quiet-Sun, active regions and micro-flares. We present recent data analysis to test the presence of hot plasma in and outside of active regions observed during the two flights, focusing on the differential emission measure distribution of the non-flaring corona.

  6. Quiet Sonic Booms: A NASA and Industry Progress Report

    NASA Technical Reports Server (NTRS)

    Larson, David Nils; Martin, Roy; Haering, Edward A.

    2011-01-01

    The purpose of this Oral Presentation is to present a progress report on NASA and Industry efforts related to Quiet Sonic Boom Program activities. This presentation will review changes in aircraft shaping to produce quiet supersonic booms and associated supersonic flight test methods and results. In addition, new flight test profiles have been recently developed that have allowed for the generation of sonic booms of varying intensity. These new flight test profiles have allowed for ground testing of the response of various building structures to sonic booms and the associated public acceptability to various sonic boom intensities. The new flight test profiles and associated ground measurement test methods will be reviewed. Finally, this Oral Presentation will review the International Regulatory requirements that would be involved to change aviation regulation and allow for overland quiet supersonic flight.

  7. Quiet Sonic Booms: A NASA and Industry Progress Report

    NASA Technical Reports Server (NTRS)

    Larson, David Nils; Martin, Roy; Haering, Edward A.

    2011-01-01

    The purpose of this Oral Presentation is to present a progress report on NASA and Industry efforts related to Quiet Sonic Boom Program activities. This presentation will review changes in aircraft shaping to produce quiet supersonic booms and associated supersonic flight test methods and results. In addition, new flight test profiles have been recently developed that have allowed for the generation of sonic booms of varying intensity. These new flight test profiles have allowed for ground testing of the response of various building structures to sonic booms and the associated public acceptability to various sonic boom intensities. The new flight test profiles and associated ground measurement test methods will be reviewed. Finally, this Oral Presentation will review the International Regulatory requirements that would be involved to change aviation regulation and allow for overland quiet supersonic flight.

  8. High latitude equivalent current systems during extremely quiet times

    NASA Technical Reports Server (NTRS)

    Rostoker, G.; Chen, A. J.; Yasuhara, F.; Akasofu, S.-I.; Kawasaki, K.

    1974-01-01

    The magnetic perturbation patterns in the polar cap and auroral zone regions are obtained for extremely quiet days using two different techniques. It is shown that the form of the equivalent current flow pattern is extremely sensitive to the level of quietness, and that even so-called quiet days are at times disturbed by substorm activity. Certain characteristic equivalent flow not typically observed during substorms is noted in the polar cap, and this flow appears to be associated with effects of polar cap perturbations discussed by Svalgaard (1973). A region of equatorward flow at high latitudes near the dawn meridian, appears to be Hall current driven by an eastward electric field. The dayside sub-auroral zone is dominated by the Sq-current system, while the nightside shows no significant current flow in the absence of substorm activity.

  9. UBIQUITOUS ROTATING NETWORK MAGNETIC FIELDS AND EXTREME-ULTRAVIOLET CYCLONES IN THE QUIET SUN

    SciTech Connect

    Zhang Jun; Liu Yang E-mail: yliu@sun.stanford.edu

    2011-11-01

    We present Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) observations of EUV cyclones in the quiet Sun. These cyclones are rooted in the rotating network magnetic fields (RNFs). Such cyclones can last several to more than 10 hr and, at the later phase, they are found to be associated with EUV brightenings (microflares) and even EUV waves. SDO Helioseismic and Magnetic Imager (HMI) observations show a ubiquitous presence of RNFs. Using HMI line-of-sight magnetograms on 2010 July 8, we find 388 RNFs in an area of 800 x 980 arcsec{sup 2} near the disk center where no active region is present. The sense of rotation shows a weak hemisphere preference. The unsigned magnetic flux of the RNFs is about 4.0 x 10{sup 21} Mx, or 78% of the total network flux. These observational phenomena at small scale reported in this Letter are consistent with those at large scale in active regions. The ubiquitous RNFs and EUV cyclones over the quiet Sun may suggest an effective way to heat the corona.

  10. Quiet Sun Magnetic Field Evolution Observed with Hinode SOT and IRIS

    NASA Astrophysics Data System (ADS)

    Fischer, C. E.; Bello González, N.; Rezaei, R.

    2016-04-01

    We study two physical processes that can be commonly observed in the quiet sun and involve temporal evolution of the magnetic field: convective collapse and flux cancellation. The aim is to investigate the response of the chromosphere to the magnetic events in the photosphere below. We have calibrated and aligned a co-spatial and co-temporal 3 hour quiet sun time series observed with the Hinode SOT (Solar Optical Telescope) and the IRIS (Interface Region Imaging Spectrograph) satellites. Convective collapse events are identified in the photosphere by inverting spectropolarimetric data and searching for magnetic field intensification, preceded by a downflow and accompanied by the development of a bright point in Ca II H images. We find a corresponding downflow in the low chromosphere as deduced from IRIS Mg II k and h spectra and an ensuing oscillatory velocity pattern. We use magnetograms in the high photosphere to study pairs of magnetic elements involved in flux cancellation and find an increase in the entire quasi-continuum of the IRIS Mg II k and h spectrum following the flux cancellation process and indicating a substantial energy deposit into the lower atmosphere.

  11. Pi2 Pulsations During Extremely Quiet Geomagnetic Condition: Van Allen Probe Observations

    NASA Astrophysics Data System (ADS)

    Ghamry, Essam

    2017-06-01

    A ultra low frequency (ULF) wave, Pi2, has been reported to occur during periods of extremely quiet magnetospheric and solar wind conditions. And no statistical study on the Pi2 has been performed during extremely quiet conditions, using satellite observations to the author’s knowledge. Also Pi2 pulsations in the space fluxgate magnetometers near perigee failed to attract scientist’s attention previously. In this paper, Pi2 pulsations detected by the Van Allen probe satellites (VAP-A & VAP-B) were investigated statistically. During the period from October 2012 to December 2014, ninety six Pi2 events were identified using VAP when Kp = 0 while using Kakioka (KAK, L = 1.23) as a reference ground station. Seventy five events had high coherence between VAP-Bz and H components at KAK station. As a result, it was found that 77 % of the events had power spectra between 5 and 12 mHz, which differs from the regular Pi2 band range of from 6.7 to 25 mHz. In addition, it was shown that it is possible to observe Pi2 pulsations from space fluxgate magnetometers near perigee. Twenty two clean Pi2 pulsations were found where L < 4 and four examples of Pi2 oscillations at different L shells are presented in this paper.

  12. Analysis and design of quiet hypersonic wind tunnels

    NASA Astrophysics Data System (ADS)

    Naiman, Hadassah

    The purpose of the present work is to integrate CFD into the design of quiet hypersonic wind tunnels and the analysis of their performance. Two specific problems are considered. The first problem is the automated design of the supersonic portion of a quiet hypersonic wind tunnel. Modern optimization software is combined with full Navier-Stokes simulations and PSE stability analysis to design a Mach 6 nozzle with maximum quiet test length. A response surface is constructed from a user-specified set of contour shapes and a genetic algorithm is used to find the "optimal contour", which is defined as the shortest nozzle with the maximum quiet test length. This is achieved by delaying transition along the nozzle wall. It is found that transition is triggered by Goertler waves, which can be suppressed by including a section of convex curvature along the contour. The optimal design has an unconventional shape described as compound curvature, which makes the contour appear slightly wavy. The second problem is the evaluation of a proposed modification of the test section in the Boeing/AFOSR Mach 6 Quiet Tunnel. The new design incorporates a section of increased diameter with the intention of enabling the tunnel to start in the presence of larger blunt models. Cone models with fixed base diameter (and hence fixed blockage ratio) are selected for this study. Cone half-angles from 15° to 75° are examined to ascertain the effect of ii the strength of the test model shock wave on the tunnel startup. The unsteady, laminar, compressible Navier-Stokes equations are solved. The resulting flowfields are analyzed to see what affect the shocks and shear layers have on the quiet test section flow. This study indicates that cone angles ≤20° allow the tunnel to start. Keywords. automated optimization, response surface, parabolized stability equations, compound curvature, laminar, wind tunnel, unstart, test section.

  13. Quiet turbofan STOL aircraft for short haul transportation, volume 1

    NASA Technical Reports Server (NTRS)

    Renshaw, J. H.

    1973-01-01

    The characteristics for a quiet turbofan short takeoff aircraft for short haul transportation applications are discussed. The following subjects are examined: (1) representative aircraft configurations, characteristics, and costs associated with the short haul aircraft development and operation, (2) critical technology and technology related problems to be resolved in successful introduction of representative short haul aircraft, (3) relationships between quiet short takeoff aircraft and the economic and social viability of short haul, and (4) identification of high payoff technology areas. In order to properly evaluate the candidate aircraft designs and to determine their economic viability and community acceptance, a real world scenario was developed and projected to 1990.

  14. Quiet geomagnetic field representation for all days and latitudes

    USGS Publications Warehouse

    Campbell, W.H.; Schiffmacher, E.R.; Arora, B.R.

    1992-01-01

    Describes a technique for obtaining the quiet-time geomagnetic field variation expected for all days of the year and distribution of latitudes from a limited set of selected quiet days within a year at a discrete set of locations. A data set of observatories near 75??E longitude was used as illustration. The method relies upon spatial smoothing of the decomposed spectral components. An evaluation of the fidelity of the resulting model shows correlation coefficients usually above 0.9 at the lower latitudes and near 0.7 at the higher latitudes with variations identified as dependent upon season and field element. -from Authors

  15. SLOW MAGNETOACOUSTIC WAVES OBSERVED ABOVE A QUIET-SUN REGION IN A DARK CAVITY

    SciTech Connect

    Liu Jiajia; Zhou Zhenjun; Wang Yuming; Liu Rui; Liao Chijian; Shen Chenglong; Zheng Huinan; Miao Bin; Su Zhenpeng; Wang, S.; Wang Bin E-mail: ymwang@ustc.edu.cn

    2012-10-20

    Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magnetoacoustic (MA) waves are one of the important types of magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above active regions and coronal holes, but were rarely found elsewhere. Here, we investigate a 'tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40-110 Mm above a quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including phase speed, compression ratio, and kinetic energy density, are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3-5 minutes).

  16. Magnetic network elements in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Jin, Chunlan; Wang, Jingxiu

    2013-07-01

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

  17. Remote Observations of Ion Temperatures in the Quiet Time Magnetosphere

    NASA Technical Reports Server (NTRS)

    Keesee, A. M.; Buzulukova, N.; Goldstein, J.; McComas, D. J.; Scime, E. E.; Spence, H.; Fok, M. C.; Tallaksen, K.

    2011-01-01

    Ion temperature analysis of the first energetic neutral atom images of the quiet -time, extended magnetosphere provides evidence of multiple regions of ion heating. This study confirms the existence of a dawn -dusk asymmetry in ion temperature predicted for quiescent magnetospheric conditions by Spence and Kivelson (1993) and demonstrates that it is an inherent magnetospheric feature.

  18. On the hazard of quiet vehicles to pedestrians and drivers.

    PubMed

    Wogalter, Michael S; Lim, Raymond W; Nyeste, Patrick G

    2014-09-01

    The need to produce more efficient and less polluting vehicles has encouraged mass production of alternative energy vehicles, such as hybrid and electric cars. Many of these vehicles are capable of very quiet operation. While reducing noise pollution is desirable, quieter vehicles could negatively affect pedestrian safety because of reduced sound cues compared to louder internal combustion engines. Three studies were performed to investigate people's concern about this issue. In Study 1, a questionnaire completed by 378 people showed substantial positive interest in quiet hybrid and electric cars. However, they also indicated concern about the reduced auditory cues of quiet vehicles. In Study 2, 316 participants rated 14 sounds that could be potentially added to quiet alternative-energy vehicles. The data showed that participants did not want annoying sounds, but preferred adding "engine" and "hum" sounds relative to other types of sounds. In Study 3, 24 persons heard and rated 18 actual sounds within 6 categories that were added to a video of a hybrid vehicle driving by. The sounds most preferred were "engine" followed by "white noise" and "hum". Implications for adding sounds to facilitate pedestrians' detection of moving vehicles and for aiding drivers' awareness of speed are discussed. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  19. Remote Observations of Ion Temperatures in the Quiet Time Magnetosphere

    NASA Technical Reports Server (NTRS)

    Keesee, A. M.; Buzulukova, N.; Goldstein, J.; McComas, D. J.; Scime, E. E.; Spence, H.; Fok, M. C.; Tallaksen, K.

    2011-01-01

    Ion temperature analysis of the first energetic neutral atom images of the quiet -time, extended magnetosphere provides evidence of multiple regions of ion heating. This study confirms the existence of a dawn -dusk asymmetry in ion temperature predicted for quiescent magnetospheric conditions by Spence and Kivelson (1993) and demonstrates that it is an inherent magnetospheric feature.

  20. The importance of Radio Quiet Zone (RQZ) for radio astronomy

    NASA Astrophysics Data System (ADS)

    Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

    2013-05-01

    Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

  1. Quiet eye duration and gun motion in elite shotgun shooting.

    PubMed

    Causer, Joe; Bennett, Simon J; Holmes, Paul S; Janelle, Christopher M; Williams, A Mark

    2010-08-01

    No literature exists to document skill-related differences in shotgun shooting and whether these may be a function of eye movements and control of gun motion. We therefore conducted an exploratory investigation of the visual search behaviors and gun barrel kinematics used by elite and subelite shooters across the three shotgun shooting subdisciplines. Point of gaze and gun barrel kinematics were recorded in groups of elite (n = 24) and subelite (n = 24) shooters participating in skeet, trap, and double trap events. Point of gaze was calculated in relation to the scene, while motion of the gun was captured by two stationary external cameras. Quiet eye (final fixation or tracking gaze that is located on a specific location/object in the visual display for a minimum of 100 ms) duration and onset were analyzed as well as gun motion profiles in the horizontal and vertical planes. In skeet, trap, and double trap disciplines, elite shooters demonstrated both an earlier onset and a longer relative duration of quiet eye than their subelite counterparts did. Also, in all three disciplines, quiet eye duration was longer and onset earlier during successful compared with unsuccessful trials for elite and subelite shooters. Kinematic analyses indicated that a slower movement of the gun barrel was used by elite compared with subelite shooters. Overall, stable gun motion and a longer quiet eye duration seem critical to a successful performance in all three shotgun disciplines.

  2. Strong postmidnight equatorial ionospheric anomaly observations during magnetically quiet periods

    NASA Astrophysics Data System (ADS)

    Yizengaw, Endawoke; Moldwin, Mark B.; Sahai, Yogeshwar; de Jesus, Rodolfo

    2009-12-01

    We have examined the quiet time equatorial electrodynamics of the ionosphere in the postmidnight sector using satellite, GPS total electron content (TEC) and ionosonde data. ROCSAT-1 vertical drift data are used to estimate the equatorial ionosphere electrodynamics, TOPEX altimeter and GPS TEC are used to obtain the density structure of the ionosphere. Ionosonde data measure the postmidnight F layer height as function of local time. We analyzed 4 years (2001-2004) of quiet time (Kp ≤ 3) observations in the postmidnight sector. We found that very strong equatorial ionospheric anomalies (EIAs) in the postmidnight (0100-0500 LT) sector during magnetically quiet periods are common and are capable of disrupting satellite communication and navigation systems. The coordinated multi-instrument observations clearly demonstrate that these strong EIAs are not simply the EIAs observed in earlier local time sectors that have corotated into the postmidnight sector as has been suggested by previous studies. We demonstrate that they are triggered by a reversed vertically upward drift, which is suggested to be generated by thermospheric neutral wind through F region dynamo. This clearly demonstrates that the Earth's postmidnight ionosphere is dynamic even in magnetically quiet periods contrary to simple theoretical model predictions.

  3. Design note about a 75 KVA quiet power distribution system

    SciTech Connect

    Visser, A.T.

    1984-04-05

    This note describes a 75KVA quiet power distribution system for X 653 in neutrino Lab D. It is fed from the regular AC distribution which exists in the building and it has no standby power. Its purpose is to remove electrical disturbances which are present on the regular AC distribution.

  4. The Reform Movement and the Quiet Crisis in Gifted Education.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.; Reis, Sally M.

    1991-01-01

    Gifted education faces a quiet crisis as reform movements focus on cosmetic administrative changes in school organization and management rather than interaction among teachers, students, and the material to be learned. Two goals of American education are presented: providing the best possible education to promising students and improving the…

  5. The Reform Movement and the Quiet Crisis in Gifted Education.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.; Reis, Sally M.

    1991-01-01

    Gifted education faces a quiet crisis as reform movements focus on cosmetic administrative changes in school organization and management rather than interaction among teachers, students, and the material to be learned. Two goals of American education are presented: providing the best possible education to promising students and improving the…

  6. NASA quiet short-haul research aircraft experimenters' handbook

    NASA Technical Reports Server (NTRS)

    Mccracken, R. C.

    1980-01-01

    A summary of guidelines and particulars concerning the use of the NASA-Ames Research Center Quiet Short-Haul Research Aircraft for applicable flight experiments is presented. Procedures for submitting experiment proposals are included along with guidelines for experimenter packages, an outline of experiment selection processes, a brief aircraft description, and additional information regarding support at Ames.

  7. Contemplative Pedagogy: A Quiet Revolution in Higher Education

    ERIC Educational Resources Information Center

    Zajonc, Arthur

    2013-01-01

    During the last fifteen years a quiet pedagogical revolution has taken place in colleges, universities, and community colleges across the United States and increasingly around the world. Often flying under the name "contemplative pedagogy," it offers to its practitioners a wide range of educational methods that support the development of…

  8. The history of a quiet-sun magnetic element revealed by IMaX/SUNRISE

    SciTech Connect

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Schmidt, Wolfgang

    2014-07-01

    Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective collapse mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here, we report on the formation and subsequent evolution of one such photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0.''15-0.''18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne solar observatory. The equipartition field strength magnetic element is the result of the merging of several same polarity magnetic flux patches, including a footpoint of a previously emerged loop. The magnetic structure is then further intensified to kG field strengths by convective collapse. The fine structure found within the flux concentration reveals that the scenario is more complex than can be described by a thin flux tube model with bright points and downflow plumes being established near the edges of the kG magnetic feature. We also observe a daisy-like alignment of surrounding granules and a long-lived inflow toward the magnetic feature. After a subsequent weakening process, the field is again intensified to kG strengths. The area of the magnetic feature is seen to change in anti-phase with the field strength, while the brightness of the bright points and the speed of the downflows varies in phase. We also find a relation between the brightness of the bright point and the presence of upflows within it.

  9. The History of a Quiet-Sun Magnetic Element Revealed by IMaX/SUNRISE

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Solanki, Sami K.; Schmidt, Wolfgang

    2014-07-01

    Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective collapse mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here, we report on the formation and subsequent evolution of one such photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0.''15-0.''18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne solar observatory. The equipartition field strength magnetic element is the result of the merging of several same polarity magnetic flux patches, including a footpoint of a previously emerged loop. The magnetic structure is then further intensified to kG field strengths by convective collapse. The fine structure found within the flux concentration reveals that the scenario is more complex than can be described by a thin flux tube model with bright points and downflow plumes being established near the edges of the kG magnetic feature. We also observe a daisy-like alignment of surrounding granules and a long-lived inflow toward the magnetic feature. After a subsequent weakening process, the field is again intensified to kG strengths. The area of the magnetic feature is seen to change in anti-phase with the field strength, while the brightness of the bright points and the speed of the downflows varies in phase. We also find a relation between the brightness of the bright point and the presence of upflows within it.

  10. Estimation of the Magnetic Flux Emergence Rate in the Quiet Sun from Sunrise Data

    NASA Astrophysics Data System (ADS)

    Smitha, H. N.; Anusha, L. S.; Solanki, S. K.; Riethmüller, T. L.

    2017-03-01

    Small-scale internetwork (IN) features are thought to be the major source of fresh magnetic flux in the quiet Sun. During its first science flight in 2009, the balloon-borne observatory Sunrise captured images of the magnetic fields in the quiet Sun at a high spatial resolution. Using these data we measure the rate at which the IN features bring magnetic flux to the solar surface. In a previous paper it was found that the lowest magnetic flux in small-scale features detected using the Sunrise observations is 9 × 1014 Mx. This is nearly an order of magnitude smaller than the smallest fluxes of features detected in observations from the Hinode satellite. In this paper, we compute the flux emergence rate (FER) by accounting for such small fluxes, which was not possible before Sunrise. By tracking the features with fluxes in the range {10}15{--}{10}18 Mx, we measure an FER of 1100 {Mx} {{cm}}-2 {{day}}-1. The smaller features with fluxes ≤slant {10}16 Mx are found to be the dominant contributors to the solar magnetic flux. The FER found here is an order of magnitude higher than the rate from Hinode, obtained with a similar feature tracking technique. A wider comparison with the literature shows, however, that the exact technique of determining the rate of the appearance of new flux can lead to results that differ by up to two orders of magnitude, even when applied to similar data. The causes of this discrepancy are discussed and first qualitative explanations proposed.

  11. Numerical simulations of quiet sun magnetism: On the contribution from a small-scale dynamo

    SciTech Connect

    Rempel, M.

    2014-07-10

    We present a series of radiative MHD simulations addressing the origin and distribution of the mixed polarity magnetic field in the solar photosphere. To this end, we consider numerical simulations that cover the uppermost 2-6 Mm of the solar convection zone and we explore scales ranging from 2 km to 25 Mm. We study how the strength and distribution of the magnetic field in the photosphere and subsurface layers depend on resolution, domain size, and boundary conditions. We find that 50% of the magnetic energy at the τ = 1 level comes from fields with the less than 500 G strength and that 50% of the energy resides on scales smaller than about 100 km. While the probability distribution functions are essentially independent of resolution, properly describing the spectral energy distribution requires grid spacings of 8 km or smaller. The formation of flux concentrations in the photosphere exceeding 1 kG requires a mean vertical field strength greater than 30-40 G at τ = 1. The filling factor of kG flux concentrations increases with overall domain size as the magnetic field becomes organized by larger, longer-lived flow structures. A solution with a mean vertical field strength of around 85 G at τ = 1 requires a subsurface rms field strength increasing with depth at the same rate as the equipartition field strength. We consider this an upper limit for the quiet Sun field strength, which implies that most of the convection zone is magnetized close to the equipartition. We discuss these findings in view of recent high-resolution spectropolarimetric observations of quiet Sun magnetism.

  12. On the Temporal Evolution of the Disk Counterpart of Type II Spicules in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Sekse, D. H.; Rouppe van der Voort, L.; De Pontieu, B.

    2013-02-01

    The newly established type II spicule has been speculated to provide enough hot plasma to play an important role in the mass loading and heating of the solar corona. With the identification of rapid blueshifted excursions (RBEs) as the on-disk counterpart of type II spicules we have analyzed three different high-quality timeseries with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on La Palma and subjected to an automated detection routine to detect a large number of RBEs for statistical purposes. Our observations are of a quiet-Sun region at disk center and we find lower Doppler velocities, 15-40 km s-1, and Doppler widths, 2-15 km s-1, of RBEs than in earlier coronal hole studies, 30-50 km s-1 and 7-23 km s-1, respectively. In addition, we examine the spatial dependence of Doppler velocities and widths along the RBE axis and conclude that there is no clear trend to this over the field of view or in individual RBEs in the quiet Sun at disk center. These differences with previous coronal hole studies are attributed to the more varying magnetic field configuration in quiet-Sun conditions. Using an extremely high-cadence data set has allowed us to improve greatly on the determination of lifetimes of RBEs, which we find to range from 5 to 60 s with an average lifetime of 30 s, as well as the transverse motions in RBEs, with transverse velocities up to 55 km s-1 and averaging 12 km s-1. Furthermore, our measurements of the recurrence rates of RBEs provide important new constraints on coronal heating by spicules. We also see many examples of a sinusoidal wave pattern in the transverse motion of RBEs with periods averaging 54 s and amplitudes from 21.5 to 129 km which agrees well with previous studies of wave motion in spicules at the limb. We interpret the appearance of RBEs over their full length within a few seconds as the result of a combination of three kinds of motions as is earlier reported for spicules. Finally, we look at the

  13. Global empirical model of critical frequency of the ionospheric F2-layer for quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Shubin, V. N.

    2017-07-01

    Using the foF2 database obtained from satellites and ground-based ionospheric stations, we have constructed a global empirical model of the critical frequency of the ionospheric F2-layer (SDMF2—Satellite and Digisonde Data Model of the F2 layer) for quiet geomagnetic conditions ( Kp < 3). The input parameters of this model are the geographical coordinates, UT, day, month, year, and the integral index F10.7 ( day, τ = 0.96) of solar activity for a given day. The SDMF2 model was based on the Legendre method for the spatial expansion of foF2 monthly medians to 12 in latitude and 8 in longitude of spherical harmonics. The resulting spatial coefficients have been expanded by the Fourier method in three spherical harmonics with respect to UT. The effect of the saturation of critical frequency of the ionospheric F2-layer at high solar activity was described in the SDMF2 model by foF2 as a logarithmic function of F10.7 ( day, τ = 0.96). The difference between the SDMF2 and IRI models is a maximum at low solar activity as well as in the Southern Hemisphere and in the oceans. The testing on the basis of ground-based and satellite data has indicated that the SDMF2 model is more accurate than the IRI model.

  14. Inverted Temperature Loops in The Quiet Corona: Properties and Physical Origin

    NASA Astrophysics Data System (ADS)

    Huang, Z.; van der Holst, B.; Frazin, R. A.; Nuevo, F.; Vásquez, A. M.; Manchester, W.; Sokolov, I.; Gombosi, T. I.

    2013-12-01

    Huang et al. 2012 revealed the existence of inverted temperature ("down") loops, in which temperature decreases with height, as well as the usual ("up") loops, in which the temperature increases with height, in the quiet solar Corona. It was shown that the "down" loops are mostly located at low latitudes and "up" loops most often appear in high latitudes. A recent study by Nuevo et al. 2013 confirmed this discovery and further showed that the "down" loop population is greatest at solar minimum; and strongly decreases with solar activity. Moreover, the "down" loops were found to be associated with values of the plasma beta greater than about unity, while the "up" loops were associated with much smaller values of beta. Here, we review the properties of "up" and "down" loops, and employ a state-of-the-art global MHD model to understand the physics of these loops as well as to investigate their thermodynamic stability. The 3D MHD model uses a phenomenological wave dissipation model based on wave reflection (proportional to the Alfvén speed gradients) and turbulent dissipation.

  15. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...? 222.35 Section 222.35 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL... § 222.35 What are the minimum requirements for quiet zones? The following requirements apply to quiet... within the quiet zone must be treated in accordance with this section and § 222.25 of this part. (f) All...

  16. 14 CFR Appendix A to Subpart U of... - GCNP Quiet Aircraft Technology Designation

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false GCNP Quiet Aircraft Technology Designation... to Subpart U of Part 93—GCNP Quiet Aircraft Technology Designation This appendix contains procedures for determining the GCNP quiet aircraft technology designation status for each aircraft subject...

  17. 14 CFR Appendix A to Subpart U of... - GCNP Quiet Aircraft Technology Designation

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false GCNP Quiet Aircraft Technology Designation... to Subpart U of Part 93—GCNP Quiet Aircraft Technology Designation This appendix contains procedures for determining the GCNP quiet aircraft technology designation status for each aircraft subject...

  18. 14 CFR Appendix A to Subpart U of... - GCNP Quiet Aircraft Technology Designation

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false GCNP Quiet Aircraft Technology Designation... to Subpart U of Part 93—GCNP Quiet Aircraft Technology Designation This appendix contains procedures for determining the GCNP quiet aircraft technology designation status for each aircraft subject to...

  19. 14 CFR Appendix A to Subpart U of... - GCNP Quiet Aircraft Technology Designation

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false GCNP Quiet Aircraft Technology Designation... to Subpart U of Part 93—GCNP Quiet Aircraft Technology Designation This appendix contains procedures for determining the GCNP quiet aircraft technology designation status for each aircraft subject to...

  20. 14 CFR Appendix A to Subpart U of... - GCNP Quiet Aircraft Technology Designation

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false GCNP Quiet Aircraft Technology Designation... to Subpart U of Part 93—GCNP Quiet Aircraft Technology Designation This appendix contains procedures for determining the GCNP quiet aircraft technology designation status for each aircraft subject...

  1. General overview of the solar activity effects on the lower ionosphere

    NASA Technical Reports Server (NTRS)

    Danilov, A. D.

    1989-01-01

    Solar activity influences the ionospheric D region. That influence manifests itself both in the form of various solar induced disturbances and in the form of the D region dependence on solar activity parameters (UV-flux, interplanetary magnetic field, solar wind etc.) in quiet conditions. Relationship between solar activity and meteorological control of the D region behavior is considered in detail and examples of strong variations of aeronomical parameters due to solar or meteorological events are given.

  2. The quiet Sun average Doppler shift of coronal lines up to 2 MK

    NASA Astrophysics Data System (ADS)

    Dadashi, N.; Teriaca, L.; Solanki, S. K.

    2011-10-01

    Context. The average Doppler shift shown by spectral lines formed from the chromosphere to the corona reveals important information on the mass and energy balance of the solar atmosphere, providing an important observational constraint to any models of the solar corona. Previous spectroscopic observations of vacuum ultra-violet (VUV) lines have revealed a persistent average wavelength shift of lines formed at temperatures up to 1 MK. At higher temperatures, the behaviour is still essentially unknown. Aims: Here we analyse combined SUMER (Solar Ultraviolet Measurements of Emitted Radiation)/SoHO (Solar and Heliospheric Observatory) and EIS (EUV Imaging Spectrometer)/Hinode observations of the quiet Sun around disk centre to determine, for the first time, the average Doppler shift of several spectral lines formed between 1 and 2 MK, where the largest part of the quiet coronal emission is formed. Methods: The measurements are based on a novel technique applied to EIS spectra to measure the difference in Doppler shift between lines formed at different temperatures. Simultaneous wavelength-calibrated SUMER spectra allow establishing the absolute value at the reference temperature of T ≈ 1 MK. Results: The average line shifts at 1 MK < T < 1.8 MK are modestly, but clearly bluer than those observed at 1 MK. By accepting an average blue shift of about (-1.8 ± 0.6) km s-1 at 1 MK (as provided by SUMER measurements), this translates into a maximum Doppler shift of (-4.4 ± 2.2) km s-1 around 1.8 MK. The measured value appears to decrease to about (-1.3 ± 2.6) km s-1 at the Fe xv formation temperature of 2.1 MK. Conclusions: The measured average Doppler shift between 0.01 and 2.1 MK, for which we provide a parametrisation, appears to be qualitatively and roughly quantitatively consistent with what foreseen by 3D coronal models where heating is produced by dissipation of currents induced by photospheric motions and by reconnection with emerging magnetic flux.

  3. Orbiting solar observatory 8 high resolution ultraviolet spectrometer experiment

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Oscillations, physical properties of the solar atmosphere, motions in the quiet solar atmosphere, coronal holes, motions in solar active regions, solar flares, the structure of plage regions, an atlas, and aeronomy are summarized. Photometric sensitivity, scattered light, ghosts, focus and spectral resolution, wavelength drive, photometric sensitivity, and scattered light, are also summarized. Experiments are described according to spacecraft made and experiment type. Some of the most useful data reduction programs are described.

  4. Quantitative Global Heat Transfer in a Mach-6 Quiet Tunnel

    NASA Technical Reports Server (NTRS)

    Sullivan, John P.; Schneider, Steven P.; Liu, Tianshu; Rubal, Justin; Ward, Chris; Dussling, Joseph; Rice, Cody; Foley, Ryan; Cai, Zeimin; Wang, Bo; Woodiga, Sudesh

    2012-01-01

    This project developed quantitative methods for obtaining heat transfer from temperature sensitive paint (TSP) measurements in the Mach-6 quiet tunnel at Purdue, which is a Ludwieg tube with a downstream valve, moderately-short flow duration and low levels of heat transfer. Previous difficulties with inferring heat transfer from TSP in the Mach-6 quiet tunnel were traced to (1) the large transient heat transfer that occurs during the unusually long tunnel startup and shutdown, (2) the non-uniform thickness of the insulating coating, (3) inconsistencies and imperfections in the painting process and (4) the low levels of heat transfer observed on slender models at typical stagnation temperatures near 430K. Repeated measurements were conducted on 7 degree-half-angle sharp circular cones at zero angle of attack in order to evaluate the techniques, isolate the problems and identify solutions. An attempt at developing a two-color TSP method is also summarized.

  5. Quiet Clean General Aviation Turbofan (QCGAT) technology study, volume 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The preliminary design of an engine which satisfies the requirements of a quiet, clean, general aviation turbofan (QCGAT) engine is described. Also an experimental program to demonstrate performance is suggested. The T700 QCGAT engine preliminary design indicates that it will radiate noise at the same level as an aircraft without engine noise, have exhaust emissions within the EPA 1981 Standards, have lower fuel consumption than is available in comparable size engines, and have sufficient life for five years between overhauls.

  6. Towards High-Reynolds Number Quiet Flow in Hypersonic Tunnels

    DTIC Science & Technology

    2009-02-23

    MOC procedure is used in an inverse design mode to determine an inviscid nozzle wall contour that produces the desired uniform exit flow. This...determine the optimal shape of the supersonic nozzle to achieve laminar flow on the nozzle walls and hence quiet flow in the test section. In the...methodology was developed to determine the optimal shape of the supersonic nozzle to achieve laminar flow on the nozzle walls and maximize the length of

  7. Dark Skies are a Universal Resource. So are Quiet Skies!

    NASA Astrophysics Data System (ADS)

    Maddalena, Ronald J.; Heatherly, S.

    2008-05-01

    You've just purchased your first telescope. But where to set it up? Certainly not a WalMart parking lot. Too much light pollution! In the same way that man-made light obscures our night sky and blinds ground-based optical telescopes, man-made radio signals blind radio telescopes as well. NRAO developed the Quiet Skies project to increase awareness of radio frequency interference (RFI) and radio astronomy in general by engaging students in local studies of RFI. To do that we created a sensitive detector which measures RFI. We produced 20 of these, and assembled kits containing detectors and supplementary materials for loan to schools. Students conduct experiments to measure the properties of RFI in their area, and input their measurements into a web-based data base. The Quiet Skies project is a perfect complement to the IYA Dark Skies Awareness initiative. We hope to place 500 Quiet Skies detectors into the field through outreach to museums and schools around the world. Should we be successful, we will sustain this global initiative via a continuing loan program. One day we hope to have a publicly generated image of the Earth which shows RFI much as the Earth at Night image illustrates light pollution. The poster will present the components of the project in detail, including our plans for IYA, and various low-cost alternative strategies for introducing RFI and radio astronomy to the public. We will share the results of some of the experiments already being performed by high school students. Development of the Quiet Skies project was funded by a NASA IDEAS grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  8. The Central Engines of Radio-Quiet Quasars

    NASA Astrophysics Data System (ADS)

    Blundell, K.

    1999-05-01

    Before high-resolution imaging of the faint radio emission from Radio-Quiet Quasars was possible, two rival hypotheses had been proposed for the origin of the radio flux in these RQQs: i) it represented emission from a circumnuclear starburst (e.g., Terlevich et al 1995 and Sopp & Alexander 1991) or ii) it was caused by radio jets with powers considerably lower than those of Radio-Loud Quasars with comparable luminosities in the other wavebands (Miller et al. 1993). Imaging with the VLBA has provided a definitive test between these rival hypotheses, since a mere detection of a RQQ with the VLBA implies extreme brightness temperature, hence excluding the hypothesis that a starburst could be the sole source of emission. Blundell & Beasley (1998) have used the VLBA to image a sample of RQQs and I will discuss both the implications of these detections and subsequent multi-epoch observations which indicate superluminal motion in one of these radio-quiet quasars, further pointing towards a fundamental link between radio-quiet and radio-loud quasars.

  9. Evidence for wave heating of the quiet-sun corona

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2014-11-10

    We have measured the energy and dissipation of Alfvénic waves in the quiet Sun. A magnetic field model was used to infer the location and orientation of the magnetic field lines along which the waves are expected to travel. The waves were measured using spectral lines to infer the wave amplitude. The waves cause a non-thermal broadening of the spectral lines, which can be expressed as a non-thermal velocity v {sub nt}. By combining the spectroscopic measurements with this magnetic field model, we were able to trace the variation of v {sub nt} along the magnetic field. At each footpoint of the quiet-Sun loops, we find that waves inject an energy flux in the range of 1.3-5.5 × 10{sup 5} erg cm{sup –2} s{sup –1}. At the minimum of this range, this amounts to more than 80% of the energy needed to heat the quiet Sun. We also find that these waves are dissipated over a region centered on the top of the loops. The position along the loop where the damping begins is strongly correlated with the length of the loop, implying that the damping mechanism depends on the global loop properties rather than on local collisional dissipation.

  10. Design and Calibration of the QUIET CMB Polarimeter

    NASA Astrophysics Data System (ADS)

    Buder, Immanuel

    2011-04-01

    QUIET is a large--angular-scale Cosmic Microwave Background (CMB) polarimeter designed to measure the B-mode signal from inflation. The design incorporates a new time-stream "double-demodulation" technique, a 1.4-m Mizuguchi--Dragone telescope, natural sky rotation, and frequent boresight rotation to minimize systematic contamination. The levels of contamination in the inflationary signal are below r=0.1, the best yet achieved by any B-mode polarimeter. Moreover, QUIET is unique among B-mode polarimeters in using a large focal-plane array of miniaturized High--Electron-Mobility Transistor (HEMT) based coherent detectors. These detectors take advantage of a breakthrough in microwave-circuit packaging to achieve a field sensitivity of 69,K√s. QUIET has collected > 10,000,ours of data and recently released results from the first observing season at Q band (43 GHz). Analysis of W-band (95-GHz) data is ongoing. I will describe the Q-band calibration plan which uses a combination of astronomical and artificial sources to convert the raw data into polarization measurements with small and well-understood calibration errors. I will also give a status report on calibration for the upcoming W-band results.

  11. Centre-to-limb properties of small, photospheric quiet-Sun jets

    NASA Astrophysics Data System (ADS)

    Rubio da Costa, F.; Solanki, S. K.; Danilovic, S.; Hizberger, J.; Martínez-Pillet, V.

    2015-02-01

    Context. Strongly Doppler-shifted Stokes V profiles have been detected in the quiet Sun with the IMaX instrument on-board the SUNRISE stratospheric balloon-borne telescope. High velocities are required to produce such signals, hence these events have been interpreted as jets, although other sources are also possible. Aims: We aim to characterize the variation of the main properties of these events (occurrence rate, lifetime, size, and velocities) with their position on the solar disk between disk centre and the solar limb. Methods: These events were identified in SUNRISE/IMaX data according to the same objective criteria at all available positions on the solar disk. Their properties were determined using standard techniques. Results: Our study yielded a number of new insights into this phenomenon. Most importantly, the number density of these events is independent of the heliocentric angle, meaning that the investigated supersonic flows are nearly isotropically distributed. Size and lifetime are also nearly independent of the heliocentric angle, while their intensity contrast increases towards the solar limb. The Stokes V jets are associated with upflow velocities deduced from Stokes I, which are stronger towards the limb. Their intensity decreases with time, while their line-of-sight velocity does not display a clear temporal evolution. Their association with linear polarization signals decreases towards the limb. Conclusions: The density of events appears to be independent of heliocentric angle, establishing that they are directed nearly randomly. If these events are jets triggered by magnetic reconnection between emerging magnetic flux and the ambient field, then our results suggest that there is no preferred geometry for the reconnection process.

  12. New View on Quiet-Sun Photospheric Dynamics Offered by NST Data

    NASA Astrophysics Data System (ADS)

    Abramenko, Valentyna; Yurchyshyn, V.; Goode, P. R.

    2011-05-01

    Recent observations of the quiet sun photosphere obtained with the 1.6 meter New Solar telescope (NST) of Big Bear Solar observatory (BBSO) delivered new information about photospheric fine structures and their dynamics, as well as posing new questions. The 2-hour uninterrupted data set of solar granulation obtained under excellent seeing conditions on August 3, 2010 (with cadence of 10 sec) was the basis for the study. Statistical analysis of automatically detected and tracked magnetic bright points (MBPs) showed that the MBPs population monotonically increases as their size decreases, down to 60-70 km. Our analysis shows that if the smallest magnetic flux tubes exist, their size is still smaller that 60-70 km, which impose strong restrictions on the modeling of these structures. We also found that the distributions of the MBP's size and lifetime do not follow a traditional Gaussian distribution, typical for random processes. Instead, it follows a log-normal distribution, typical for avalanches, catastrophes, stock market data, etc. Our data set also demonstrated that a majority (98.6 %) of MBPs are short live (<2 min). This remarkable fact was not obvious from previous studies because an extremely high time cadence was required. The fact indicates that the majority of MBPs appear for a very short time (tens of seconds), similar to other transient features, for example, chromospheric jets. The most important point here is that these small and short living MBPs significantly increase dynamics (flux emergence, collapse into MBPs, and magnetic flux recycling) of the solar surface magnetic fields.

  13. NASA gateways at L1 and L2 and the radio-quiet Moon Farside imperative

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2005-07-01

    NASA is currently studying the possibility of establishing future space bases at either of the libration points (also called Lagrangian points) L1 and L2 of the Earth Moon system. Two more similar points L1 and L2 of the Sun Earth system are also under consideration. Such possible future space bases are called Gateways in the NASA jargon. Each Gateway has its own pros and cons in terms of gravitational pull, distance from the Earth, and targets attainable by future spacecraft departing from the Gateway. A preliminary, concise review of these alternative possibilities is presented in this paper. We claim, however, that an extra factor has to be included in the NASA scenario also. This is the Radio-Quiet Moon Farside Imperative, called simply the Farside Imperative hereafter. This imperative is the need to keep at least the central part of the Farside of the Moon free from Radio Frequency Interference (RFI) coming from the Earth and shielded by the Moon's spherical body. In fact, the Farside of the Moon, and the Quiet Cone that extends into space above it for a few thousands of kilometers, represent a unique outpost for humankind: they are the only place close to the Earth where all radio-garbage produced by modern human civilization cannot reach. Thus, an array of radio antennas located there would sense the rest of the universe to an unprecedented degree of radio cleanliness, and, hence, of radio details. Not only would astrophysics and radio astronomy in general greatly benefit from this radio-quiet environment, but we would possibly achieve there for the first time a neat radio contact with an extraterrestrial civilization harboring somewhere else in the Galaxy (SETI) that could be too noisy to be detected on Earth. It is thus felt that a fair balance has to be reached between the astronautical drive to enlarge the exploration of the solar system and the imperative to keep the Farside of the Moon radio-clean. This paper puts forward a set of constructing

  14. Spatial deconvolution of spectropolarimetric data: an application to quiet Sun magnetic elements

    NASA Astrophysics Data System (ADS)

    Quintero Noda, C.; Asensio Ramos, A.; Orozco Suárez, D.; Ruiz Cobo, B.

    2015-07-01

    Context. One of the difficulties in extracting reliable information about the thermodynamical and magnetic properties of solar plasmas from spectropolarimetric observations is the presence of light dispersed inside the instruments, known as stray light. Aims: We aim to analyze quiet Sun observations after the spatial deconvolution of the data. We examine the validity of the deconvolution process with noisy data as we analyze the physical properties of quiet Sun magnetic elements. Methods: We used a regularization method that decouples the Stokes inversion from the deconvolution process, so that large maps can be quickly inverted without much additional computational burden. We applied the method on Hinode quiet Sun spectropolarimetric data. We examined the spatial and polarimetric properties of the deconvolved profiles, comparing them with the original data. After that, we inverted the Stokes profiles using the Stokes Inversion based on Response functions (SIR) code, which allow us to obtain the optical depth dependence of the atmospheric physical parameters. Results: The deconvolution process increases the contrast of continuum images and makes the magnetic structures sharper. The deconvolved Stokes I profiles reveal the presence of the Zeeman splitting while the Stokes V profiles significantly change their amplitude. The area and amplitude asymmetries of these profiles increase in absolute value after the deconvolution process. We inverted the original Stokes profiles from a magnetic element and found that the magnetic field intensity reproduces the overall behavior of theoretical magnetic flux tubes, that is, the magnetic field lines are vertical in the center of the structure and start to fan when we move far away from the center of the magnetic element. The magnetic field vector inferred from the deconvolved Stokes profiles also mimic a magnetic flux tube but in this case we found stronger field strengths and the gradients along the line-of-sight are larger

  15. 49 CFR 222.43 - What notices and other information are required to create or continue a quiet zone?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... create or continue a quiet zone? 222.43 Section 222.43 Transportation Other Regulations Relating to... Groups of Crossings-Quiet Zones § 222.43 What notices and other information are required to create or... receipt requested, of its intent to create a New Quiet Zone or New Partial Quiet Zone under § 222.39...

  16. Mesogranulation and small-scale dynamo action in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Bushby, P. J.; Favier, B.

    2014-02-01

    Context. Regions of quiet Sun generally exhibit a complex distribution of small-scale magnetic field structures, which interact with the near-surface turbulent convective motions. Furthermore, it is probable that some of these magnetic fields are generated locally by a convective dynamo mechanism. In addition to the well-known granular and supergranular convective scales, various observations have indicated that there is an intermediate scale of convection, known as mesogranulation, with vertical magnetic flux concentrations accumulating preferentially at the boundaries of mesogranules. Aims: Our aim is to investigate the small-scale dynamo properties of a convective flow that exhibits both granulation and mesogranulation, comparing our findings with solar observations. Methods: Adopting an idealised model for a localised region of quiet Sun, we use numerical simulations of compressible magnetohydrodynamics, in a three-dimensional Cartesian domain, to investigate the parametric dependence of this system (focusing particularly upon the effects of varying the aspect ratio and the Reynolds number). Results: In purely hydrodynamic convection, we find that mesogranulation is a robust feature of this system provided that the domain is wide enough to accommodate these large-scale motions. The mesogranular peak in the kinetic energy spectrum is more pronounced in the higher Reynolds number simulations. We investigate the dynamo properties of this system in both the kinematic and the nonlinear regimes and we find that the dynamo is always more efficient in larger domains, when mesogranulation is present. Furthermore, we use a filtering technique in Fourier space to demonstrate that it is indeed the larger scales of motion that are primarily responsible for driving the dynamo. In the nonlinear regime, the magnetic field distribution compares very favourably to observations, both in terms of the spatial distribution and the measured field strengths.

  17. Coronal extension of the MURaM radiative MHD code: From quiet sun to flare simulations

    NASA Astrophysics Data System (ADS)

    Rempel, Matthias D.; Cheung, Mark

    2016-05-01

    We present a new version of the MURaM radiative MHD code, which includes a treatment of the solar corona in terms of MHD, optically thin radiative loss and field-aligned heat conduction. In order to relax the severe time-step constraints imposed by large Alfven velocities and heat conduction we use a combination of semi-relativistic MHD with reduced speed of light ("Boris correction") and a hyperbolic formulation of heat conduction. We apply the numerical setup to 4 different setups including a mixed polarity quiet sun, an open flux region, an arcade solution and an active region setup and find all cases an amount of coronal heating sufficient to maintain a corona with temperatures from 1 MK (quiet sun) to 2 MK (active region, arcade). In all our setups the Poynting flux is self-consistently created by photospheric and sub-photospheric magneto-convection in the lower part of our simulation domain. Varying the maximum allowed Alfven velocity ("reduced speed of light") leads to only minor changes in the coronal structure as long as the limited Alfven velocity remains larger than the speed of sound and about 1.5-3 times larger than the peak advection velocity. We also found that varying details of the numerical diffusivities that govern the resistive and viscous energy dissipation do not strongly affect the overall coronal heating, but the ratio of resistive and viscous energy dependence is strongly dependent on the effective numerical magnetic Prandtl number. We use our active region setup in order to simulate a flare triggered by the emergence of a twisted flux rope into a pre-existing bipolar active region. Our simulation yields a series of flares, with the strongest one reaching GOES M1 class. The simulation reproduces many observed properties of eruptions such as flare ribbons, post flare loops and a sunquake.

  18. Inclinations of small quiet-Sun magnetic features based on a new geometric approach

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, S.; Solanki, S. K.; Lagg, A.; Bellot Rubio, L. R.; van Noort, M.; Feller, A.; Danilovic, S.

    2014-09-01

    Context. High levels of horizontal magnetic flux have been reported in the quiet-Sun internetwork, often based on Stokes profile inversions. Aims: Here we introduce a new method for deducing the inclination of magnetic elements and use it to test magnetic field inclinations from inversions. Methods: We determine accurate positions of a set of small, bright magnetic elements in high spatial resolution images sampling different photospheric heights obtained by the Sunrise balloon-borne solar observatory. Together with estimates of the formation heights of the employed spectral bands, these provide us with the inclinations of the magnetic features. We also compute the magnetic inclination angle of the same magnetic features from the inversion of simultaneously recorded Stokes parameters. Results: Our new, geometric method returns nearly vertical fields (average inclination of around 14° with a relatively narrow distribution having a standard deviation of 6°). In strong contrast to this, the traditionally used inversions give almost horizontal fields (average inclination of 75 ± 8°) for the same small magnetic features, whose linearly polarised Stokes profiles are adversely affected by noise. We show that for such magnetic features inversions overestimate the flux in horizontal magnetic fields by an order of magnitude. Conclusions: The almost vertical field of bright magnetic features from our geometric method is clearly incompatible with the nearly horizontal magnetic fields obtained from the inversions. This indicates that the amount of magnetic flux in horizontal fields deduced from inversions is overestimated in the presence of weak Stokes signals, in particular if Stokes Q and U are close to or under the noise level. Inversions should be used with great caution when applied to data with no clear Stokes Q and no U signal. By combining the proposed method with inversions we are not just improving the inclination, but also the field strength. This technique

  19. Identification of quiet and disturbed days through IEC profile features over anomaly crest region

    NASA Astrophysics Data System (ADS)

    Devi, M.; Barman, M. K.; Barbara, A. K.

    2002-08-01

    In this paper, the ionospheric electron content (IEC) profile features, have been utilized for extraction of a few parameters and the parameters are used for assertion of a certain day as quiet (Q) or disturbed (D). The IEC values taken for the study cover two solar activity periods (high and low) and are based on VHF RB data collected over Guwahati /(26.2°N, /91.75°E). The paper describes methods for extraction of parameters like profile factor, /P and anomaly factor, PEA from IEC profiles separately for three seasons (summer, winter and equinox). The definitions of Q and D days are made through profile features and the threshold values of ΣKp for each season are evaluated. The relations between ΣKp and /P factor, ΣKp and PEA are established after corrections for solar activity condition. The prediction and assertion of Q/D days are then made by examining IEC profiles for the cases where IEC data were not used for the parameter extraction.

  20. Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

    SciTech Connect

    Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato; Tokumaru, Munetoshi; Shiota, Daikou; Isobe, Hiroaki; Asai, Ayumi; Miyamoto, Mayu; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander; Yaji, Kentaro; Yamada, Manabu

    2014-06-20

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  1. Two-Component Fitting of Coronal-Hole and Quiet-Sun He I 1083 nm Spectra

    NASA Astrophysics Data System (ADS)

    Jones, H. P.; Malanushenko, E. V.

    2001-05-01

    We present reduction techniques and first results for detailed fitting of solar spectra obtained with the NASA/National Solar Observatory Spectromagnetograph (NASA/NSO SPM) over a 2 nm bandpass centered on the He I 1083 nm line. The observation for this analysis was a spectra-spectroheliogram obtained at the NSO/Kitt Peak Vacuum Telescope (KPVT) on 00 Apr 17 at 21:46 UT spanning an area of 512 x 900 arc-seconds; the field of view included a coronal hole near disk center as well as surrounding quiet sun. Since the He I line is very weak and blended with nearby solar and telluric lines, accurate determination of the continuum intensity as a function of wavelength is crucial. We have modified the technique of Malanushenko et al. (1992; AA 259, 567) to tie regions of continuua and the wings of spectral lines which show little variation over the image to standard reference spectra such as the NSO Fourier Transform Spectrometer atlas (Wallace et al. 1993; NSO Tech Report #93-001). We performed detailed least-squares fits of spectra from selected areas, accounting for all the known telluric and solar absorbers in the spectral bandpass. The best physically consistent fits to the Helium lines were obtained with Gaussian profiles from two components (one ``cool'', characteristic of the upper chromosphere; one ``hot'', representing the cool transition region at 2-3 x 104 K). In the coronal hole, the transition-region component, shifted by 6-7 km/s to the blue, is mildly dominant, consistent with mass outflow as suggested by Dupree et al., (1996; Ap. J.~467, 121). In quiet-sun spectra there is less evidence of outward flow, and the chromospheric component is more important. All our fitted spectra show a very weak unidentified absorption feature at 1082.880 nm in the red wing of the nearby Si I line.

  2. Solar Magnetic Explosions, Spicules, and the Heliosphere

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Yamauchi, Yohei

    2004-01-01

    We present an example of each of the following observed characteristics of the magnetic origins of quiet-region coronal heating, spicules, macrospicules, and coronal mass ejections (CMEs). (1) In quiet regions, the luminosity of the corona is roughly proportional to the edge length of the underlying photospheric magnetic network. (2) Spicules and EUV explosive events are concentrated at the edges of the magnetic network. (3) Many macrospicules have the magnetic structure of a surge rooted around an inclusion of opposite-polarity magnetic flux. (4) CMEs and eruptive flares are driven by explosions of sheared magnetic fields rooted along polarity dividing lines (neutral lines) in the photospheric magnetic flux. These characteristics together suggest that the mainstay of the heliosphere, the corona/solar wind rooted in quiet regions and coronal holes, may be driven by myriads of tiny magnetic explosions at the network edges, explosions like those that drive CMEs but of vastly smaller scale. If so, the steady solar wind and the CMEs that disrupt it both have the same root cause: explosions of initially-closed, strongly-sheared, bipolar magnetic fields. The photospheric vector magnetograms, chromospheric filtergrams, EUV spectra, and coronal images from Solar-B are expected to have sufficient sensitivity, spatial resolution, and cadence to test this scenario for coronal heating in quiet regions and coronal holes. This work was supported by NASA/OSS through its Solar and Heliospheric Physics SR and T Program and Sun-Earth Connection GI Program.

  3. Solar Magnetic Explosions, Spicules, and the Heliosphere

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Yamauchi, Yohei

    2004-01-01

    We present an example of each of the following observed characteristics of the magnetic origins of quiet-region coronal heating, spicules, macrospicules, and coronal mass ejections (CMEs). (1) In quiet regions, the luminosity of the corona is roughly proportional to the edge length of the underlying photospheric magnetic network. (2) Spicules and EUV explosive events are concentrated at the edges of the magnetic network. (3) Many macrospicules have the magnetic structure of a surge rooted around an inclusion of opposite-polarity magnetic flux. (4) CMEs and eruptive flares are driven by explosions of sheared magnetic fields rooted along polarity dividing lines (neutral lines) in the photospheric magnetic flux. These characteristics together suggest that the mainstay of the heliosphere, the corona/solar wind rooted in quiet regions and coronal holes, may be driven by myriads of tiny magnetic explosions at the network edges, explosions like those that drive CMEs but of vastly smaller scale. If so, the steady solar wind and the CMEs that disrupt it both have the same root cause: explosions of initially-closed, strongly-sheared, bipolar magnetic fields. The photospheric vector magnetograms, chromospheric filtergrams, EUV spectra, and coronal images from Solar-B are expected to have sufficient sensitivity, spatial resolution, and cadence to test this scenario for coronal heating in quiet regions and coronal holes. This work was supported by NASA/OSS through its Solar and Heliospheric Physics SR and T Program and Sun-Earth Connection GI Program.

  4. Moon Farside, Quiet Cone and the "RLI" Experiment

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    The Farside of the Moon is a unique place. Radio emissions coming from the Earth, and notably the from Telecommunication Satellites orbiting the Earth, don't get there since shielded by the Moon's spherical body. A radio telescope placed inside Crater Daedalus (just at the center of the Farside) would thus sense no man-made RFI (Radio Frequency Interference) and would be ideal for all radio astronomical and SETI searches. Above the Farside, a conical region extends into space, the ``Quiet Cone'', tangent to the Moon surface and with apex a few thousands of kilometers above the Moon. The size of the Quiet Cone, however, is only vaguely known, and changes in time, because the orbits of secret military satellites around the Earth are of course unknown. The only way to know the current, actual size of the Quiet Cone is to send a radiometer into orbit around the Moon and find out where the RFI coming from the Earth is actually shielded and where it is not. The RLI Experiment (RLI is an acronym for ``Radiometro Lunare Italiano'', i.e. Italian Moon Radiometer), is currently under construction by an Italian team coordinated by this author as Principal Investigator. The RLI is hopefully going to be put into orbit around the Moon before 2007. This will be done by placing the RLI radiometer aboard the ``Trailbalzer'', the first American commercial Moon spacecraft, built by TransOrbital Inc.. The RLI Experiment will take direct measurements of the intensity of man-made RFI around two frequencies: The band in between 10.7 and 11.8 GHz (main frequency band of European TV transmissions and, in part, also of American TV transmissions) and The band in between 10 Hz and 10 kHz, to get a Fourier spectrum of the very thin Moon atmosphere. A scientific and technical description of the RLI mission is given in this paper.

  5. Design Guidelines for Quiet Fans and Pumps for Space Vehicles

    NASA Technical Reports Server (NTRS)

    Lovell, John S.; Magliozzi, Bernard

    2008-01-01

    This document presents guidelines for the design of quiet fans and pumps of the class used on space vehicles. A simple procedure is presented for the prediction of fan noise over the meaningful frequency spectrum. A section also presents general design criteria for axial flow fans, squirrel cage fans, centrifugal fans, and centrifugal pumps. The basis for this report is an experimental program conducted by Hamilton Standard under NASA Contract NAS 9-12457. The derivations of the noise predicting methods used in this document are explained in Hamilton Standard Report SVHSER 6183, "Fan and Pump Noise Control," dated May 1973 (6).

  6. Modeling the quiet time inner plasma sheet protons

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Ping; Lyons, Larry R.; Chen, Margaret W.; Wolf, Richard A.

    2001-04-01

    In order to understand the characteristics of the quiet time inner plasma sheet protons, we use a modified version of the Magnetospheric Specification Model to simulate the bounce averaged electric and magnetic drift of isotropic plasma sheet protons in an approximately self-consistent magnetic field. Proton differential fluxes are assigned to the model boundary to mimic a mixed tail source consisting of hot plasma from the distant tail and cooler plasma from the low latitude boundary layer (LLBL). The source is local time dependent and is based on Geotail observations and the results of the finite tail width convection model. For the purpose of self-consistently simulating plasma motion and a magnetic field, the Tsyganenko 96 magnetic field model is incorporated with additional adjustable ring-current shaped current loops. We obtain equatorial proton flow and midnight and equatorial profiles of proton pressure, number density, and temperature. We find that our results agree well with observations. This indicates that the drift motion dominates the plasma transport in the quiet time inner plasma sheet. Our simulations show that cold plasma from the LLBL enhances the number density and the proton pressure in the inner plasma sheet and decreases the dawn-dusk asymmetry of the equatorial proton pressure. From our approximately force-balanced simulations the magnetic field responds to the increase of pressure gradient force in the inner plasma sheet by changing its configuration to give a stronger magnetic force. At the same time, the plasma dynamics is affected by the changing field configuration and its associated pressure gradient force becomes smaller. Our model predicts a quiet time magnetic field configuration with a local depression in the equatorial magnetic field strength at the inner edge of the plasma sheet and a cross-tail current separated from the ring current, results that are supported by observations. A scale analysis of our results shows that in the

  7. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. In these studies, the total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

  8. NASA/GE quiet engine C acoustic test results

    NASA Technical Reports Server (NTRS)

    Kazin, S. B.; Pass, J. E.

    1974-01-01

    The acoustic investigation and evaluation of the C propulsion turbofan engine are discussed. The engine was built as a part of the Quiet Engine Program. The objectives of the program are as follows: (1) to determine the noise levels produced turbofan bypass engines, (2) to demonstrate the technology and innovations which will reduce the production and radiation of noise in turbofan engines, and (3) to acquire experimental acoustic and aerodynamic data for high bypass turbofan engines to provide a better understanding of noise production mechanisms. The goals of the program called for a turbofan engine 15 to 20 PNdB quieter than currently available engines in the same thrust class.

  9. The NuSTAR view of radio-quiet AGN

    NASA Astrophysics Data System (ADS)

    Marinucci, Andrea

    AUTHORS: A. Marinucci and the NuSTAR Team ABSTRACT: The Nuclear Spectroscopic Telescope Array (NuSTAR), thanks to its improved sensitivity in hard X-rays with respect to coded aperture observatories, is providing new and exciting results on radio-quiet AGN. In this talk I will present results from the NuSTAR AGN Physics program after the first two years of science operations. In particular, measurements of the black hole spin and coronal temperature in nearby sources will be discussed.

  10. Magnetic location of C IV events in the quiet network

    NASA Technical Reports Server (NTRS)

    Porter, Jason G.; Reichmann, Ed J.; Moore, Ronald L.; Harvey, Karen L.

    1986-01-01

    Ultraviolet Spectrograph and Polarimeter (UVSP) observations of C IV intensity in the quiet sun were examined and compared to magnetograms and He I 10830 A spectroheliograms from Kitt Peak National Laboratory. The observations were made between 3 and 9 April, 1985. Spatially rastered UVSP intensity measurements were obtained at 11 wavelength positions in the 1548 A line of C IV. It was concluded that the stochastic process whereby convective shuffling of loop footprints leads to many topically dissipative events in active regions and the larger bipoles treated here continues to operate in regions of fewer, weaker flux loops, but the resulting events above threshold are less frequent.

  11. Statistical evolution of quiet-Sun small-scale magnetic features using Sunrise observations

    NASA Astrophysics Data System (ADS)

    Anusha, L. S.; Solanki, S. K.; Hirzberger, J.; Feller, A.

    2017-02-01

    The evolution of small magnetic features in quiet regions of the Sun provides a unique window for probing solar magneto-convection. Here we analyze small-scale magnetic features in the quiet Sun, using the high resolution, seeing-free observations from the Sunrise balloon borne solar observatory. Our aim is to understand the contribution of different physical processes, such as splitting, merging, emergence and cancellation of magnetic fields to the rearrangement, addition and removal of magnetic flux in the photosphere. We have employed a statistical approach for the analysis and the evolution studies are carried out using a feature-tracking technique. In this paper we provide a detailed description of the feature-tracking algorithm that we have newly developed and we present the results of a statistical study of several physical quantities. The results on the fractions of the flux in the emergence, appearance, splitting, merging, disappearance and cancellation qualitatively agrees with other recent studies. To summarize, the total flux gained in unipolar appearance is an order of magnitude larger than the total flux gained in emergence. On the other hand, the bipolar cancellation contributes nearly an equal amount to the loss of magnetic flux as unipolar disappearance. The total flux lost in cancellation is nearly six to eight times larger than the total flux gained in emergence. One big difference between our study and previous similar studies is that, thanks to the higher spatial resolution of Sunrise, we can track features with fluxes as low as 9 × 1014 Mx. This flux is nearly an order of magnitude lower than the smallest fluxes of the features tracked in the highest resolution previous studies based on Hinode data. The area and flux of the magnetic features follow power-law type distribution, while the lifetimes show either power-law or exponential type distribution depending on the exact definitions used to define various birth and death events. We have

  12. Empirical determination of the temperature stratification in the photosphere of the quiet Sun

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Ricort, G.; Aime, C.

    2013-06-01

    Context. Detailed realistic 3D simulations of the photosphere of the Sun are now available, but 1D models of the average quiet-Sun photosphere are still widely used, in particular for spectro-polarimetric inversions. Aims: Here we present an empirical determination of the average radiation temperature variations as a function of the geometrical height above the continuum formation level in the solar photosphere. Methods: We used high resolution spectroscopic scans in the 630 nm Fe i line pair at varying heliocentric angles along the north-south polar axis of the Sun, made with SOT onboard Hinode. Implementing a new method for image reconstruction, we obtained images of the photospheric granulation at constant continuum opacity levels, from the upper photosphere seen at line centers to the low photosphere. The Fourier cross-spectra of images at different opacity levels were computed, and we derived the formation depths of images without referring to any atmospheric model, by measuring the slope of the cross-spectrum phase. Results: A modified Milne-Eddington model for the line formation was tested by comparing it with the average line-intensity profiles observed at solar disk center. It yields consistent results for the FeI 630.2 nm line, whereas the FeI line at 630.1 nm is not well reproduced by the model. We ascribe this discrepancy to non-LTE effects in the line formation processes. The average image intensities at the different FeI 630.2 nm levels were used to determine the depth-variation of the temperature for an average 1D model of the quiet photosphere. We compared our empirical temperature model with the widely used FALC model. Both models agree well for the temperature variations with the continuum optical depth. But in the low photosphere, the temperature gradient we measure with respect to the geometrical height is significantly softer than in Model C. We argue that some of the assumptions used to solve the pseudohydrostatic equilibrium in semi

  13. Dark energy and the quietness of the local Hubble flow

    NASA Astrophysics Data System (ADS)

    Axenides, M.; Perivolaropoulos, L.

    2002-06-01

    The linearity and quietness of the local (<10 Mpc) Hubble flow (LHF) in view of the very clumpy local universe is a long standing puzzle in standard and in open CDM (cold dark matter) cosmogony. The question addressed in this paper is whether the antigravity component of the recently discovered dark energy can cool the velocity flow enough to provide a solution to this puzzle. We calculate the growth of matter fluctuations in a flat universe containing a fraction ΩX(t0) of dark energy obeying the time independent equation of state pX=wρX. We find that dark energy can indeed cool the LHF. However the dark energy parameter values required to make the predicted velocity dispersion consistent with the observed value vrms~=40 km/s have been ruled out by other observational tests constraining the dark energy parameters w and ΩX. Therefore despite the claims of recent qualitative studies, dark energy with time independent equation of state cannot by itself explain the quietness and linearity of the local Hubble flow.

  14. Quiet time mass composition at near-geosynchronous altitudes

    NASA Technical Reports Server (NTRS)

    Strangeway, R. J.; Kaye, S. M.

    1986-01-01

    Mass composition data acquired from the near-geosynchronous SCATHA spacecraft during magnetically quiet times are analyzed. The time intervals over which data were included in the study span some four months in the spring and summer of 1979. This allows a reasonable coverage in both L shell and magnetic local time. At the higher L shells, L greater than 6.5, the mass composition data are consistent with sunward convection of plasma sheet particles. Protons and alpha particle fluxes peak near the 90 deg pitch angle. There is evidence that the alpha particle spatial distribution has a sharp inner edge near L = 6.5. At lower L values, the proton characteristics change. The density of protons above 1 keV decreases, while the lower-energy protons show an increase in density. The oxygen ions show a similar change, in that there is a large increase in the lower-energy oxygen ions from high L to low L, especially, in the dusk and midnight local time sectors. This suggests that the ionosphere may be continuously supplying plasma to the inner magnetosphere even during magnetically quiet times.

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

    NASA Astrophysics Data System (ADS)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

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

  16. Photospheric Magnetic Field Properties of Flaring vs. Flare-Quiet Active Regions I: Data, General Approach, and Statistical Results

    NASA Astrophysics Data System (ADS)

    Leka, K. D.; Barnes, G.

    2003-05-01

    Photospheric vector magnetic field data from the U. Hawai`i Imaging Vector Magnetograph are examined for pre-event signatures unique to solar energetic phenomena. Parameters are constructed from B(x,y) to describe (for example) the distributions of the field, spatial gradients of the field, vertical current, current helicity, ''twist'' parameter α and magnetic shear angles. A quantitative statistical approach employing discriminant analysis and Hotelling's T2-test is applied to the magnitude and temporal evolution of parameters from 24 flare-event and flare-quiet epochs from seven active regions. We demonstrate that (1) when requiring a flare-unique signature, numerous candidate parameters are nullified by considering flare-quiet epochs, (2) a more robust method exists for estimating error rates than conventional ''truth tables'', (3) flaring and flare-quiet populations do not necessarily have low error rates for classification even when statistically distinguishable, and that (4) simultaneous consideration of a large number of variables is required to produce acceptable error rates. That is, when the parameters are considered individually, they show little ability to differentiate between the two populations; multi-variable combinations can discriminate the populations and/or result in perfect classification tables. In lieu of constructing a single all-variable discriminant function to quantify the flare-predictive power of the parameters considered, we devise a method whereby all permutations of the four-variable discriminant functions are ranked by Hotelling's T2. We present those parameters (e.g. the temporal increase of the kurtosis of the spatial distribution of the vertical current density) which consistently appear in the best combinations, indicating that they may play an important role in defining a pre-event photospheric state. While no single combination is clearly the best discriminator, we demonstrate here the requisite approach: include flare-quiet

  17. DYNAMICS OF MULTI-CORED MAGNETIC STRUCTURES IN THE QUIET SUN

    SciTech Connect

    Requerey, Iker S.; Iniesta, Jose Carlos Del Toro; Rubio, Luis R. Bellot; Pillet, Valentín Martínez; Solanki, Sami K.; Schmidt, Wolfgang

    2015-09-01

    We report on the dynamical interaction of quiet-Sun magnetic fields and granular convection in the solar photosphere as seen by Sunrise. We use high spatial resolution (0.″15–0.″18) and temporal cadence (33 s) spectropolarimetric Imaging Magnetograph eXperiment data, together with simultaneous CN and Ca ii H filtergrams from Sunrise Filter Imager. We apply the SIR inversion code to the polarimetric data in order to infer the line of sight velocity and vector magnetic field in the photosphere. The analysis reveals bundles of individual flux tubes evolving as a single entity during the entire 23 minute data set. The group shares a common canopy in the upper photospheric layers, while the individual tubes continually intensify, fragment and merge in the same way that chains of bright points in photometric observations have been reported to do. The evolution of the tube cores are driven by the local granular convection flows. They intensify when they are “compressed” by surrounding granules and split when they are “squeezed” between two moving granules. The resulting fragments are usually later regrouped in intergranular lanes by the granular flows. The continual intensification, fragmentation and coalescence of flux results in magnetic field oscillations of the global entity. From the observations we conclude that the magnetic field oscillations first reported by Martínez González et al. correspond to the forcing by granular motions and not to characteristic oscillatory modes of thin flux tubes.

  18. UNNOTICED MAGNETIC FIELD OSCILLATIONS IN THE VERY QUIET SUN REVEALED BY SUNRISE/IMaX

    SciTech Connect

    Martinez Gonzalez, M. J.; Asensio Ramos, A.; Manso Sainz, R.; Khomenko, E.; MartInez Pillet, V.; Lopez Ariste, A.

    2011-04-01

    We present observational evidence for oscillations of magnetic flux density in the quiet areas of the Sun. The majority of magnetic fields on the solar surface have strengths of the order of or lower than the equipartition field (300-500 G). This results in a myriad of magnetic fields whose evolution is largely determined by the turbulent plasma motions. When granules evolve they squash the magnetic field lines together or pull them apart. Here, we report on the periodic deformation of the shapes of features in circular polarization observed at high resolution with SUNRISE. In particular, we note that the area of patches with a constant magnetic flux oscillates with time, which implies that the apparent magnetic field intensity oscillates in antiphase. The periods associated with this oscillatory pattern are compatible with the granular lifetime and change abruptly, which suggests that these oscillations might not correspond to characteristic oscillatory modes of magnetic structures, but to the forcing by granular motions. In one particular case, we find three patches around the same granule oscillating in phase, which means that the spatial coherence of these oscillations can reach 1600 km. Interestingly, the same kind of oscillatory phenomenon is also found in the upper photosphere.

  19. Dynamics of Multi-cored Magnetic Structures in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Martínez Pillet, Valentín; Solanki, Sami K.; Schmidt, Wolfgang

    2015-09-01

    We report on the dynamical interaction of quiet-Sun magnetic fields and granular convection in the solar photosphere as seen by Sunrise. We use high spatial resolution (0.″15-0.″18) and temporal cadence (33 s) spectropolarimetric Imaging Magnetograph eXperiment data, together with simultaneous CN and Ca ii H filtergrams from Sunrise Filter Imager. We apply the SIR inversion code to the polarimetric data in order to infer the line of sight velocity and vector magnetic field in the photosphere. The analysis reveals bundles of individual flux tubes evolving as a single entity during the entire 23 minute data set. The group shares a common canopy in the upper photospheric layers, while the individual tubes continually intensify, fragment and merge in the same way that chains of bright points in photometric observations have been reported to do. The evolution of the tube cores are driven by the local granular convection flows. They intensify when they are “compressed” by surrounding granules and split when they are “squeezed” between two moving granules. The resulting fragments are usually later regrouped in intergranular lanes by the granular flows. The continual intensification, fragmentation and coalescence of flux results in magnetic field oscillations of the global entity. From the observations we conclude that the magnetic field oscillations first reported by Martínez González et al. correspond to the forcing by granular motions and not to characteristic oscillatory modes of thin flux tubes.

  20. Dynamic Flaring Non-potential Fields on Quiet Sun Network Scales

    NASA Astrophysics Data System (ADS)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.

    2016-05-01

    We report on the identification of dynamic flaring non-potential structures on quiet Sun (QS) supergranular network scales. Data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory allow for the high spatial and temporal resolution of this diverse class of compact structures. The rapidly evolving non-potential events presented here, with lifetimes <10 minutes, are on the order of 10″ in length. Thus, they contrast significantly with well-known active region (AR) non-potential structures such as high-temperature X-ray and EUV sigmoids (>100″) and micro-sigmoids (>10″) with lifetimes on the order of hours to days. The photospheric magnetic field environment derived from the Helioseismic and Magnetic Imager shows a lack of evidence for these flaring non-potential fields being associated with significant concentrations of bipolar magnetic elements. Of much interest to our events is the possibility of establishing them as precursor signatures of eruptive dynamics, similar to notions for AR sigmoids and micro-sigmoids, but associated with uneventful magnetic network regions. We suggest that the mixed network flux of QS-like magnetic environments, though unresolved, can provide sufficient free magnetic energy for flaring non-potential plasma structuring. The appearance of non-potential magnetic fields could be a fundamental process leading to self-organized criticality in the QS-like supergranular network and contribute to coronal heating, as these events undergo rapid helicial and vortical relaxations.

  1. Predictors of noise annoyance in noisy and quiet urban streets.

    PubMed

    Paunović, Katarina; Jakovljević, Branko; Belojević, Goran

    2009-06-01

    Although noise annoyance is a major public health problem in urban areas, there is a lack of published data on predictors for noise annoyance in acoustically different urban environments. The aim of the study was to assess the predictive value of various factors on noise annoyance in noisy and quiet urban streets. Equivalent noise levels [Leq (dBA)] were measured during day, evening and night times in all of the streets of a central Belgrade municipality. Based on 24-hour noise levels, the streets were denoted as noisy (24-hour Leq over 65 dBA), or quiet (24-hour Leq under 55 dBA). A cross-sectional study was performed on 1954 adult residents (768 men and 1186 women), aged 18-80 years. Noise annoyance was estimated using a self-report five-graded scale. In both areas, two multivariate logistic regression models were fitted: the first one with nighttime noise indicators and the other one with parameters for 24-hour noise exposure. In noisy streets, the relevant predictors of high annoyance were: the orientation of living room/bedroom toward the street, noise annoyance at workplace, and noise sensitivity. Significant acoustical factors for high noise annoyance were: nighttime noise level [OR=1.02, 95%CI=1.00-1.04 (per decibel)], nighttime heavy traffic [OR=1.01, 95%CI=1.00-1.02 (per vehicle)]; or day-evening-night noise level (Lden) [OR=1.03, 95%CI=1.00-1.07 (per decibel)]. In quiet streets, the significant predictors were: noise sensitivity, the time spent at home daily, light vehicles at nighttime or heavy vehicles at daytime. Our study identified subjective noise sensitivity as a common annoyance predictor, regardless of noise exposure. Noise levels were important indicators of annoyance only in noisy streets, both for nighttime and 24-hour exposure. We propose that noise sensitivity is the most relevant personal trait for future studies and that nighttime noise levels might be as good as Lden in predicting annoyance in noisy urban areas.

  2. Quiet Spike Build-Up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    NASA's Dryden Flight Research Center uses a modified F-15B (836) aircraft as a testbed for a variety of flight research:experiments mounted underneath the aircraft fuselage. The F-15B was selected to fly Gulfstream Aerospace Corporation's (GAC)QuietSpike(TM)(QS) project; however, this experiment is very unique and unlike any of the previous testbed experiments flown on the F-15B. It involves the addition of a relatively long quiet spike boom attached to the radar bulkhead of the aircraft. This QS experiment is a stepping stone to airframe structural morphing technologies designed to mitigate sonic born strength of business jets over land. The QS boom is a concept in Which an aircraft's front-end would be extended prior to supersonic acceleration. This morphing would effectively lengthen the aircraft, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. Prior to flying the Quietspike(TM) experiment on the F-15B aircraft several ground vibration tests (GVT) were required in order to understand the QS modal characteristics and coupling effects with the F-15B. However, due to the project's late hardware delivery of the QS and the intense schedule, a "traditional" GVT of the mated F-1513 Quietspike(tm) ready-for-flight configuration would not have left sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. The objective of the QuietSpike (TM) build-up ground testing approach was to ultimately obtain confidence in the F-15B Quietspike(TM) finite element model (FEM) to be used for the flutter analysis. In order to obtain the F15B QS FEM with reliable foundation stiffness between the QS and the F-15B radar bulkhead as well as QS modal characteristics, several different GVT configurations were performed. EAch of the four GVT's performed had a

  3. Joint coordination during quiet stance: effects of vision.

    PubMed

    Krishnamoorthy, Vijaya; Yang, Jeng-Feng; Scholz, John P

    2005-07-01

    Stabilization of the center of mass (CM) is an important goal of the postural control system. Coordination of several joints along the human "pendulum" is required to achieve this goal. We studied the coordination among body segments with respect to horizontal CM stabilization during a quiet stance task and the effects of vision on CM stability. Subjects were asked to stand quietly on a narrow wooden block supporting only the mid-foot, with either open (EO) or closed (EC) eyes on separate trials. Instant equilibrium points (IEPs) in the center of pressure (CP) trajectory were determined when the horizontal component of the ground reaction force was zero and the CP data were decomposed into their rambling and trembling components. The joint angle, CM and CP data were divided into short cycles (time-normalized to 100 data points) or longer segments (time-normalized to 1000 data points) of equal length beginning and ending in an IEP. Motor abundance with respect to patterns of joint coordination was evaluated using the uncontrolled manifold (UCM) approach. Here, a UCM is a subspace spanning all joint combinations resulting in a given CM position. All combinations of joint angles that lie within this subspace are equivalent with respect to that CM position while joint angle combinations lying in a subspace orthogonal to the UCM lead to deviation from that CM position. UCM analysis was performed on data organized either across time within longer segments or at each point in time across multiple segments or across multiple cycles. Regardless of method of analysis, most of the variance in joint space was constrained to be within the UCM, preserving the mean CM position in both the EO and EC conditions. Joint configuration variance was significantly higher in the EC than in the EO condition although this increase occurred primarily within the UCM rather than in the orthogonal subspace that would have led to variation of the CM position. These results demonstrate the

  4. NASA's F-15B testbed aircraft with Gulfstream Quiet Spike sonic boom mitigator attached

    NASA Image and Video Library

    2006-07-06

    Gulfstream Aerospace and NASA's Dryden Flight Research Center are testing the structural integrity of a telescopic 'Quiet Spike' sonic boom mitigator on the F-15B testbed. The Quiet Spike was developed as a means of controlling and reducing the sonic boom caused by an aircraft 'breaking' the sound barrier.

  5. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing the... Administrator a written commitment to lower the potential risk to the traveling public at the crossings...

  6. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing the... Administrator a written commitment to lower the potential risk to the traveling public at the crossings...

  7. 49 CFR 222.39 - How is a quiet zone established?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.39 How... be established by implementing, at every public highway-rail grade crossing within the quiet...

  8. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing the... Administrator a written commitment to lower the potential risk to the traveling public at the crossings...

  9. 49 CFR 222.39 - How is a quiet zone established?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.39 How... be established by implementing, at every public highway-rail grade crossing within the quiet...

  10. 49 CFR 222.39 - How is a quiet zone established?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.39 How... be established by implementing, at every public highway-rail grade crossing within the quiet...

  11. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing the... Administrator a written commitment to lower the potential risk to the traveling public at the crossings...

  12. 49 CFR 222.39 - How is a quiet zone established?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.39 How... be established by implementing, at every public highway-rail grade crossing within the quiet...

  13. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing the... Administrator a written commitment to lower the potential risk to the traveling public at the crossings...

  14. Effect of Repeated Exposures on Word Learning in Quiet and Noise

    ERIC Educational Resources Information Center

    Blaiser, Kristina M.; Nelson, Peggy B.; Kohnert, Kathryn

    2015-01-01

    This study examines the impact of repeated exposures on word learning of preschool children with and without hearing loss (HL) in quiet and noise conditions. Participants were 19 children with HL and 17 peers with normal hearing (NH). Children were introduced to 16 words: 8 in quiet and 8 in noise conditions. Production and identification scores…

  15. Effect of Repeated Exposures on Word Learning in Quiet and Noise

    ERIC Educational Resources Information Center

    Blaiser, Kristina M.; Nelson, Peggy B.; Kohnert, Kathryn

    2015-01-01

    This study examines the impact of repeated exposures on word learning of preschool children with and without hearing loss (HL) in quiet and noise conditions. Participants were 19 children with HL and 17 peers with normal hearing (NH). Children were introduced to 16 words: 8 in quiet and 8 in noise conditions. Production and identification scores…

  16. 76 FR 6495 - Proposed Information Collection; National Park Service Natural Quiet Valuation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-04

    ... National Park Service Proposed Information Collection; National Park Service Natural Quiet Valuation AGENCY: National Park Service, Interior. ACTION: Notice; request for comments. SUMMARY: The National Park Service... natural quiet in national parks. Under the provisions of the Paperwork Reduction Act of 1995 and a part......

  17. 49 CFR 222.37 - Who may establish a quiet zone?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Who may establish a quiet zone? 222.37 Section 222.37 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.37...

  18. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...? 222.35 Section 222.35 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL... § 222.35 What are the minimum requirements for quiet zones? The following requirements apply to quiet... with wayside horns that conform to the requirements set forth in § 222.59 and appendix E of this...

  19. NASA's F-15B testbed aircraft lands after the first flight of the Quiet Spike project

    NASA Image and Video Library

    2006-08-10

    NASA's F-15B testbed aircraft lands after the first flight of the Quiet Spike project. The first flight was performed for evaluation purposes, and the spike was not extended. The Quiet Spike was developed as a means of controlling and reducing the sonic boom caused by an aircraft 'breaking' the sound barrier.

  20. Microflaring in Low-Lying Core Fields and Extended Coronal Heating in the Quiet Sun

    NASA Technical Reports Server (NTRS)

    Porter, Jason G.; Falconer, D. A.; Moore, Ronald L.

    1999-01-01

    We have previously reported analyses of Yohkoh SXT data examining the relationship between the heating of extended coronal loops (both within and stemming from active regions) and microflaring in core fields lying along neutral lines near their footpoints (J. G. Porter, D. A. Falconer, and R. L. Moore 1998, in Solar Jets and Coronal Plumes, ed. T. Guyenne, ESA SP-421, and references therein). We found a surprisingly poor correlation of intensity variations in the extended loops with individual microflares in the compact heated areas at their feet, despite considerable circumstancial evidence linking the heating processes in these regions. Now, a study of Fe XII image sequences from SOHO EIT show that similar associations of core field structures with the footpoints of very extended coronal features can be found in the quiet Sun. The morphology is consistent with the finding of Wang et al. (1997, ApJ 484, L75) that polar plumes are rooted at sites of mixed polarity in the magnetic network. We find that the upstairs/downstairs intensity variations often follow the trend, identified in the active region observations, of a weak correspondence. Apparently much of the coronal heating in the extended loops is driven by a type of core field magnetic activity that is "cooler" than the events having the coronal signature of microflares, i.e., activity that results in little heating within the core fields themselves. This work was funded by the Solar Physics Branch of NASA's Office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

  1. Global conditions in the solar corona from 2010 to 2017

    PubMed Central

    Morgan, Huw; Taroyan, Youra

    2017-01-01

    Through reduction of a huge data set spanning 2010–2017, we compare mean global changes in temperature, emission measure (EM), and underlying photospheric magnetic field of the solar corona over most of the last activity cycle. The quiet coronal mean temperature rises from 1.4 to 1.8 MK, whereas EM increases by almost a factor of 50% from solar minimum to maximum. An increased high-temperature component near 3 MK at solar maximum drives the increase in quiet coronal mean temperature, whereas the bulk of the plasma remains near 1.6 MK throughout the cycle. The mean, spatially smoothed magnitude of the quiet Sun magnetic field rises from 1.6 G in 2011 to peak at 2.0 G in 2015. Active region conditions are highly variable, but their mean remains approximately constant over the cycle, although there is a consistent decrease in active region high-temperature emission (near 3 MK) between the peak of solar maximum and present. Active region mean temperature, EM, and magnetic field magnitude are highly correlated. Correlation between sunspot/active region area and quiet coronal conditions shows the important influence of decaying sunspots in driving global changes, although we find no appreciable delay between changes in active region area and quiet Sun magnetic field strength. The hot coronal contribution to extreme ultraviolet (EUV) irradiance is dominated by the quiet corona throughout most of the cycle, whereas the high variability is driven by active regions. Solar EUV irradiance cannot be predicted accurately by sunspot index alone, highlighting the need for continued measurements. PMID:28740861

  2. Implementation of Quiet Time for Noise Reduction on a Medical-Surgical Unit.

    PubMed

    Applebaum, Diane; Calo, Oriana; Neville, Kathleen

    2016-12-01

    The objective of this evidence-based investigation is to determine the efficacy of a quiet-time intervention to reduce noise in the hospital setting. For many reasons, noise continues to increase in the hospital setting. In a descriptive comparative design, using a convenience sample of hospitalized patients, 80 patients were assessed on their perceptions of noise using the Patient Survey on Noise During Hospital Stay. Data revealed favorable responses to quiet time, with 70% of subjects reporting quiet-time intervention to be effective in reducing noise. Sixty percent of participants felt that 1 hour of quiet time helped to facilitate a quieter, more restful environment for the whole day. A quiet-time intervention is effective in addressing patient perception of noise while in the acute care hospital setting.

  3. Experimental quiet engine program aerodynamic performance of fan A

    NASA Technical Reports Server (NTRS)

    Giffin, R. G.; Parker, D. E.; Dunbar, L. W.

    1971-01-01

    The aerodynamic component test results are presented of fan A, one of two high-bypass-ratio, 1160 feet per second single-stage fans, which was designed and tested as part of the NASA Experimental Quiet Engine Program. This fan was designed to deliver a bypass pressure ratio of 1.50 with an adiabatic efficiency of 86.5% at a total fan flow of 950 lb/sec. It was tested with and without inlet flow distortion. A bypass total-pressure ratio of 1.52 and an adiabatic efficiency of 88.3% at a total fan flow of 962 lb/sec were actually achieved. An operating margin of 12.4% was demonstrated at design speed.

  4. Quiet High Speed Fan II (QHSF II): Final Report

    NASA Technical Reports Server (NTRS)

    Kontos, Karen; Weir, Don; Ross, Dave

    2012-01-01

    This report details the aerodynamic, mechanical, structural design and fabrication of a Honey Engines Quiet High Speed Fan II (lower hub/tip ratio and higher specific flow than the Baseline I fan). This fan/nacelle system incorporates features such as advanced forward sweep and an advanced integrated fan/fan exit guide vane design that provides for the following characteristics: (1) Reduced noise at supersonic tip speeds, in comparison to current state-of-the-art fan technology; (2) Improved aeroelastic stability within the anticipated operating envelope; and (3) Aerodynamic performance consistent with current state-of-the-art fan technology. This fan was fabricated by Honeywell and tested in the NASA Glenn 9- by 15-Ft Low Speed Wind Tunnel for aerodynamic, aeromechanical, and acoustic performance.

  5. Avco Lycoming quiet clean general aviation turbofan engine

    NASA Technical Reports Server (NTRS)

    Wilson, C. A.

    1980-01-01

    A fan module was developed using an existing turboshaft engine. The fan was designed using the latest in large engine noise control technology. A mixer was added to reduce the already low exhaust gas velocity. A nacelle incorporating sound treatment was provided for the test engine. A noise prediction model was used through the design process to evaluate the various design alternatives. Acoustic tests were then made to verify the prediction and identify the noise characteristics of the fan, core, jet, and sound treatment. Analysis of the recorded data yielded close agreement with the expected results. Core noise, as was expected, was the predominant source of noise for the quiet clean general aviation turbofan (QCGAT) engine. Flyover noise predictions were made which indicated that the Avco Lycoming QCGAT engine would meet the goals set for the QCGAT program.

  6. Quiet short-haul research aircraft familiarization document. [STOL

    NASA Technical Reports Server (NTRS)

    Mccracken, R. C.

    1979-01-01

    The design features and general characteristics of the NASA Quiet Short-Haul Research Aircraft are described. Aerodynamic characteristics and performance are discussed based on predictions and early flight-test data. Principle airplane systems, including the airborne data-acquisition system, are also described. The aircraft was designed and built to fulfill the need for a national research facility to explore the use of upper surface-blowing propulsive-lift technology in providing short takeoff and landing capability, and perform advanced experiments in various technical disciplines such as aerodynamics, propulsion, stability and control, handling qualities, avionics and flight-control systems, trailing-vortex phenomena, acoustics, structure and loads, operating systems, human factors, and airworthiness/certification criteria. An unusually austere approach using experimental shop practices resulted in a low cost and high research capability.

  7. Experimental quiet engine program aerodynamic performance of Fan C

    NASA Technical Reports Server (NTRS)

    Giffin, R. G.; Parker, D. E.; Dunbar, L. W.

    1972-01-01

    This report presents the aerodynamic component test results of Fan C, a high-bypass-ratio, low-aerodynamic-loading, 1550 feet per second (472.4 m/sec), single-stage fan, which was designed and tested as part of the NASA Experimental Quiet Engine Program. The fan was designed to deliver a bypass pressure ratio of 1.60 with an adiabatic efficiency of 84.2 percent at a total fan flow of 915 lb/sec (415.0 kg/sec). It was tested with and without inlet distortion. A bypass total-pressure ratio of 1.61 and an adiabatic efficiency of 83.9 percent at a total fan flow of 921 lb/sec (417.8 kg/sec) were actually achieved. An operating margin in excess of 14.6 percent was demonstrated at design speed.

  8. Airesearch QCGAT program. [quiet clean general aviation turbofan engines

    NASA Technical Reports Server (NTRS)

    Heldenbrand, R. W.; Norgren, W. M.

    1979-01-01

    A model TFE731-1 engine was used as a baseline for the NASA quiet clean general aviation turbofan engine and engine/nacelle program designed to demonstrate the applicability of large turbofan engine technology to small general aviation turbofan engines, and to obtain significant reductions in noise and pollutant emissions while reducing or maintaining fuel consumption levels. All new technology design for rotating parts and all items in the engine and nacelle that contributed to the acoustic and pollution characteristics of the engine system were of flight design, weight, and construction. The major noise, emissions, and performance goals were met. Noise levels estimated for the three FAR Part 36 conditions, are 10 t0 15 ENPdB below FAA requirements; emission values are considerably reduced below that of current technology engines; and the engine performance represents a TSFC improvement of approximately 9 percent over other turbofan engines.

  9. No quiet surrender: molecular guardians in multiple sclerosis brain

    PubMed Central

    Steinman, Lawrence

    2015-01-01

    The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions. PMID:25831441

  10. Electrical noise to a knee joint stabilizes quiet bipedal stance.

    PubMed

    Kimura, Tetsuya; Kouzaki, Motoki

    2013-04-01

    Studies have shown that a minute, noise-like electrical stimulation (ES) of a lower limb joint stabilizes one-legged standing (OS), possibly due to the noise-enhanced joint proprioception. To demonstrate the practical utility of this finding, we assessed whether the bipedal stance (BS), relatively stable and generally employed in daily activities, is also stabilized by the same ES method. Twelve volunteers maintained quiet BS with or without an unperceivable, noise-like ES of a knee joint. The results showed that the average amplitude, peak-to-peak amplitude, and standard deviation of the foot center of pressure in the anteroposterior direction were significantly attenuated by the ES (P<0.05). These results indicate that the BS also can be stabilized by an unperceivable, noise-like ES of a knee joint.

  11. Quiet short-haul research aircraft familiarization document, revision 1

    NASA Technical Reports Server (NTRS)

    Eppel, J. C.

    1981-01-01

    The design features and general characteristics of the Quiet Short Haul Research Aircraft are described. Aerodynamic characteristics and performance are discussed based on predictions and early flight test data. Principle airplane systems, including the airborne data acquisition system, are also described. The aircraft was designed and built to fulfill the need for a national research facility to explore the use of upper surface blowing, propulsive lift technology in providing short takeoff and landing capability, and perform advanced experiments in various technical disciplines such as aerodynamics, propulsion, stability and control, handling qualities, avionics and flight control systems, trailing vortex phenomena, acoustics, structure and loads, operating systems, human factors, and airworthiness/certification criteria. An unusually austere approach using experimental shop practices resulted in a low cost and high research capability.

  12. Kinetic plasma modeling with quiet Monte Carlo direct simulation.

    SciTech Connect

    Albright, B. J.; Jones, M. E.; Lemons, D. S.; Winske, D.

    2001-01-01

    The modeling of collisions among particles in space plasma media poses a challenge for computer simulation. Traditional plasma methods are able to model well the extremes of highly collisional plasmas (MHD and Hall-MHD simulations) and collisionless plasmas (particle-in-cell simulations). However, neither is capable of trealing the intermediate, semi-collisional regime. The authors have invented a new approach to particle simulation called Quiet Monte Carlo Direct Simulation (QMCDS) that can, in principle, treat plasmas with arbitrary and arbitrarily varying collisionality. The QMCDS method will be described, and applications of the QMCDS method as 'proof of principle' to diffusion, hydrodynamics, and radiation transport will be presented. Of particular interest to the space plasma simulation community is the application of QMCDS to kinetic plasma modeling. A method for QMCDS simulation of kinetic plasmas will be outlined, and preliminary results of simulations in the limit of weak pitch-angle scattering will be presented.

  13. Statistical analysis of quiet stance sway in 2-D.

    PubMed

    Bakshi, Avijit; DiZio, Paul; Lackner, James R

    2014-04-01

    Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909-912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model's ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior-posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation.

  14. Ionospheric manifestations of acoustic-gravity waves under quiet and disturbed conditions

    NASA Astrophysics Data System (ADS)

    Barabash, Vladimir; Chernogor, Leonid; Panasenko, Sergii; Domnin, Igor

    2014-05-01

    We present the observation results of wave disturbances in the ionosphere, which are known to be manifestations of atmospheric acoustic-gravity waves (AGWs). The observations have been conducted under quiet and naturally or artificially disturbed conditions by ionosonde and incoherent scatter radar located near Kharkiv, Ukraine. Wave disturbance parameters under quiet conditions were obtained and analysed during geophysical periods including vernal and autumn equinoxes as well as summer and winter solstices. The prevailing oscillation in ionospheric F2- layer had the period of 140 - 200 min and relative amplitude of 0.1 - 0.2. The duration of this oscillation changed from 5 - 7 to 24 hours, depending on a season. The amplitude of fluctuations with other periods was noticeably smaller. The time intervals at which the intensity of incoherent scatter signals varied quasi-periodically in the altitude range from 150 to 300 km were detected. The parameters of these variations were estimated using statistical analysis and bandpass filtering. The periods of wave processes were shown to be of 30 - 120 min, there durations did not exceed of 2 - 6 periods and relative amplitudes usually ranged from 0.03 to 0.15. The phase of oscillations was detected to propagate downwards. The vertical phase velocity of travelling ionospheric disturbances (TIDs) was estimated to be in the range from 50 to 200 m/s and increased with altitude. The observations of the partial solar eclipse on January, 4, 2011 near Kharkiv were used to study the ionospheric parameters in naturally disturbed conditions. The F2-layer critical frequency dropped by a factor of 2.1. The time delay of these variations with respect to the main magnitude of the solar disk obscuration was equal to about 16 minutes. The virtual height of signal reflection near the maximum of the F2-layer ionization increased by 70 km, and the height of the model parabolic layer increased by 10 km. Some decrease in electron density and

  15. Solar limb brightening at 350 microns

    SciTech Connect

    Lindsey, C.; Hildebrand, R.H.; Keene, J.; Whitcomb, S.E.

    1981-09-01

    We have used the NASA Infrared Telescope Facility at Mauna Kea to observe the intensity profile of the quiet solar limb in the 300--400 ..mu..m continuum. We find a significant resolved brightening of several percent over the outer 60'' of the solar limb in this band. However, the magnitude of the brightening is considerably less than that indicated by earlier observations of a total solar eclipse in integrated Sun--Moon radiation by Beckman, Lesurf, and Ross in the 1.2 mm continuum.

  16. The Total Solar Irradiance Climate Data Record

    NASA Astrophysics Data System (ADS)

    Dewitte, Steven; Nevens, Stijn

    2016-10-01

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

  17. Quiet Spike(TradeMark) Build-up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of the Gulfstream Aerospace Corporation s Quiet Spike(TradeMark) hardware were recently completed on the National Aeronautics and Space Administration Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B (836) airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the airplane, along the fuselage centerline. For the Quiet Spike(TradeMark) experiment, instead of a centerline mounting, a forward-pointing boom was attached to the radar bulkhead of the airplane. The Quiet Spike(TradeMark) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets flying over land. Prior to flying the Quiet Spike(TradeMark) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TradeMark) modal characteristics and coupling effects with the F-15B airplane. Because of flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TradeMark) ready-for-flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight-testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This report provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TradeMark) project.

  18. Focused Study on the Quiet Side Effect in Dwellings Highly Exposed to Road Traffic Noise

    PubMed Central

    Renterghem, Timothy Van; Botteldooren, Dick

    2012-01-01

    This study provides additional evidence for the positive effect of the presence of a quiet façade at a dwelling and aims at unraveling potential mechanisms. Locations with dominant road traffic noise and high Lden-levels at the most exposed façade were selected. Dwellings both with and without a quiet façade were deliberately sought out. Face-to-face questionnaires (N = 100) were taken to study the influence of the presence of a quiet side in relation to noise annoyance and sleep disturbance. As a direct effect, the absence of a quiet façade in the dwelling (approached as a front-back façade noise level difference smaller than 10 dBA) leads to an important increase of at least moderately annoyed people (odds-ratio adjusted for noise sensitivity equals 3.3). In an indirect way, a bedroom located at the quiet side leads to an even stronger reduction of the self-reported noise annoyance (odds-ratio equal to 10.6 when adjusted for noise sensitivity and front façade Lden). The quiet side effect seems to be especially applicable for noise sensitive persons. A bedroom located at the quiet side also reduces noise-induced sleep disturbances. On a loud side, bedroom windows are more often closed, however, conflicting with the preference of dwellers. PMID:23330222

  19. Focused study on the quiet side effect in dwellings highly exposed to road traffic noise.

    PubMed

    Van Renterghem, Timothy; Botteldooren, Dick

    2012-12-01

    This study provides additional evidence for the positive effect of the presence of a quiet façade at a dwelling and aims at unraveling potential mechanisms. Locations with dominant road traffic noise and high L(den)-levels at the most exposed façade were selected. Dwellings both with and without a quiet façade were deliberately sought out. Face-to-face questionnaires (N = 100) were taken to study the influence of the presence of a quiet side in relation to noise annoyance and sleep disturbance. As a direct effect, the absence of a quiet façade in the dwelling (approached as a front-back façade noise level difference smaller than 10 dBA) leads to an important increase of at least moderately annoyed people (odds-ratio adjusted for noise sensitivity equals 3.3). In an indirect way, a bedroom located at the quiet side leads to an even stronger reduction of the self-reported noise annoyance (odds-ratio equal to 10.6 when adjusted for noise sensitivity and front façade L(den)). The quiet side effect seems to be especially applicable for noise sensitive persons. A bedroom located at the quiet side also reduces noise-induced sleep disturbances. On a loud side, bedroom windows are more often closed, however, conflicting with the preference of dwellers.

  20. Aeroelastic Calculations of Quiet High- Speed Fan Performed

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Srivastava, Rakesh; Mehmed, Oral; Min, James B.

    2002-01-01

    An advanced high-speed fan was recently designed under a cooperative effort between the NASA Glenn Research Center and Honeywell Engines & Systems. The principal design goals were to improve performance and to reduce fan noise at takeoff. Scale models of the Quiet High-Speed Fan were tested for operability, performance, and acoustics. During testing, the fan showed significantly improved noise characteristics, but a self-excited aeroelastic vibration known as flutter was encountered in the operating range. Flutter calculations were carried out for the Quiet High-Speed Fan using a three-dimensional, unsteady aerodynamic, Reynolds-averaged Navier-Stokes turbomachinery code named "TURBO." The TURBO code can accurately model the viscous flow effects that can play an important role in various aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), and flutter in the presence of shock and boundary-layer interaction. Initially, calculations were performed with no blade vibrations. These calculations were at a constant rotational speed and a varying mass flow rate. The mass flow rate was varied by changing the backpressure at the exit boundary of the computational domain. These initial steady calculations were followed by aeroelastic calculations in which the blades were prescribed to vibrate harmonically in a natural mode, at a natural frequency, and with a fixed interblade phase angle between adjacent blades. The AE-prep preprocessor was used to interpolate the in-vacuum mode shapes from the structural dynamics mesh onto the computational fluid dynamics mesh and to smoothly propagate the grid deformations from the blade surface to the interior points of the grid. The aeroelastic calculations provided the unsteady aerodynamic forces on the blade surface due to blade vibrations. These forces were vector multiplied with the structural dynamic mode shape to calculate the work done on the blade during

  1. The Role of Velocity Redistribution in Enhancing the Intensity of the He II 304 A Line in the Quiet Sun Spectrum

    NASA Technical Reports Server (NTRS)

    Andretta, Vincenzo; Jordan, Stuart D.; Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Behring, William E.; Thompson, William T.; Garcia, Adriana

    1999-01-01

    We present observational evidence of the effect of small scale ("microturbulent") velocities in enhancing the intensity of the He II lambda304 line with respect to other transition region emission lines, a process we call "velocity redistribution". We first show results from the 1991 and 1993 flights of SERTS (Solar EUV Rocket Telescope and Spectrograph). The spectral resolution of the SERTS instrument was sufficient to infer that, at the spatial resolution of 5", the line profile is nearly gaussian both in the quiet Sun and in active regions. We were then able to determine, for the quiet Sun, a lower limit for the amplitude of non-thermal motions in the region of formation of the 304 A line of the order of 10 km/s. We estimated that, in the presence of the steep temperature gradients of the solar Transition Region (TR), velocities of this magnitude can significantly enhance the intensity of that line, thus at least helping to bridge the gap between calculated and observed values. We also estimated the functional dependence of such an enhancement on the relevant parameters (non-thermal velocities, temperature gradient, and pressure). We then present results from a coordinated campaign, using SOHO/CDS and H-alpha spectroheliograms from Coimbra Observatory, aimed at determining the relationship between regions of enhanced helium emission and chromospheric velocity fields and transition region emission in the quiescent atmosphere. Using these data, we examined the behavior of the He II lambda304 line in the quiet Sun supergranular network and compared it with other TR lines, in particular with O III lambda600. We also examined the association of 304 A emission with the so-called "coarse dark mottle", chromospheric structures seen in H-alpha red wing images and associated with spicules. We found that all these observations are consistent with the velocity redistribution picture.

  2. Local area networking in a radio quiet environment

    NASA Astrophysics Data System (ADS)

    Childers, Edwin L.; Hunt, Gareth; Brandt, Joseph J.

    2002-11-01

    The Green Bank facility of the National Radio Astronomy Observatory is spread out over 2,700 acres in the Allegheny Mountains of West Virginia. Good communication has always been needed between the radio telescopes and the control buildings. The National Radio Quiet Zone helps protect the Green Bank site from radio transmissions that interfere with the astronomical signals. Due to stringent Radio Frequency Interference (RFI) requirements, a fiber optic communication system was used for Ethernet transmissions on the site and coaxial cable within the buildings. With the need for higher speed communications, the entire network has been upgraded to use optical fiber with modern Ethernet switches. As with most modern equipment, the implementation of the control of the newly deployed Green Bank Telescope (GBT) depends heavily on TCP/IP. In order to protect the GBT from the commodity Internet, the GBT uses a non-routable network. Communication between the control building Local Area Network (LAN) and the GBT is implemented using a Virtual LAN (VLAN). This configuration will be extended to achieve isolation between trusted local user systems, the GBT, and other Internet users. Legitimate access to the site, for example by remote observers, is likely to be implemented using a virtual private network (VPN).

  3. Driver perceptions of the safety implications of quiet electric vehicles.

    PubMed

    Cocron, Peter; Krems, Josef F

    2013-09-01

    Previous research on the safety implications of quiet electric vehicles (EVs) has mostly focused on pedestrians' acoustic perception of EVs, and suggests that EVs are more difficult for pedestrians to hear and, therefore, compromise traffic safety. The two German field studies presented here examine the experiences of 70 drivers with low noise emissions of EVs and the drivers' long-term evaluation of the issue. Participants were surveyed via interviews and questionnaires before driving an EV for the first time, after 3 months of driving, and in the first study, again after 6 months. Based on participants' reports, a catalogue of safety-relevant incidents was composed in Study 1. The catalogue revealed that low noise-related critical incidents only rarely occur, and mostly take place in low-speed environments. The degree of hazard related to these incidents was rated as low to medium. In Study 1, driver concern for vulnerable road users as a result of low noise diminished with increasing driving experience, while perceived comfort due to this feature increased. These results were replicated in Study 2. In the second study, it was additionally examined, if drivers adjust their perceived risk of harming other road users over time. Results show that the affective assessment of risk also decreased with increased driving experience. Based on individual experience, drivers adjust their evaluation of noise-related hazards, suggesting that dangers associated with low noise emissions might be less significant than previously expected. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Progress in the development of a Mach 5 quiet tunnel

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Andere, J. B.; Stainback, P. C.; Harvey, W. D.; Srokowski, A. J.

    1977-01-01

    Various techniques to control and reduce radiated noise and the application of these techniques to a 1/2-water Mach 5 quiet tunnel are reviewed. Measurements in a small scale nozzle have shown that the upstream part of the supersonic wall boundary layer could be maintained laminar up to Reynolds numbers of nearly 4 x 1 million based on the test region length upstream of the nozzle exit. Turbulent noise levels in this test region were then reduced by an order of magnitude. To maintain low noise levels at higher Reynolds numbers, laminar flow noise shields are required. Data are presented for shields that consist of small diameter rods alined nearly parallel to the entrance flow with small gaps between the rods for boundary layer suction. Analysis and data presented on the noise shielding and reflection characteristics of flat plates and a rod-wall test panel indicate that freestream turbulent noise can be reduced by 70 to 90 deg at high Reynolds numbers. Performance estimates for the 1/2-meter tunnel are based on these results.

  5. MODELING THE CHROMOSPHERE OF A SUNSPOT AND THE QUIET SUN

    SciTech Connect

    Avrett, E.; Tian, H.; Landi, E.; Curdt, W.; Wülser, J.-P.

    2015-10-01

    Semiempirical atmospheric modeling attempts to match an observed spectrum by finding the temperature distribution and other physical parameters along the line of sight through the emitting region such that the calculated spectrum agrees with the observed one. In this paper we take the observed spectrum of a sunspot and the quiet Sun in the EUV wavelength range 668–1475 Å from the 2001 SUMER atlas of Curdt et al. to determine models of the two atmospheric regions, extending from the photosphere through the overlying chromosphere into the transition region. We solve the coupled statistical equilibrium and optically thick radiative transfer equations for a set of 32 atoms and ions. The atoms that are part of molecules are treated separately, and are excluded from the atomic abundances and atomic opacities. We compare the Mg ii k line profile observations from the Interface Region Imaging Spectrograph with the profiles calculated from the two models. The calculated profiles for the sunspot are substantially lower than the observed ones, based on the SUMER models. The only way we have found to raise the calculated Mg ii lines to agree with the observations is to introduce illumination of the sunspot from the surrounding active region.

  6. The quiet revolution in Asia's rice value chains.

    PubMed

    Reardon, Thomas; Chen, Kevin Z; Minten, Bart; Adriano, Lourdes; Dao, The Anh; Wang, Jianying; Gupta, Sunipa Das

    2014-12-01

    There is a rapid transformation afoot in the rice value chain in Asia. The upstream is changing quickly-farmers are undertaking capital-led intensification and participating in burgeoning markets for land rental, fertilizer and pesticides, irrigation water, and seed, and shifting from subsistence to small commercialized farms; in some areas landholdings are concentrating. Midstream, in wholesale and milling, there is a quiet revolution underway, with thousands of entrepreneurs investing in equipment, increasing scale, diversifying into higher quality, and the segments are undergoing consolidation and vertical coordination and integration. Mills, especially in China, are packaging and branding, and building agent networks in wholesale markets, and large mills are building direct relationships with supermarkets. The downstream retail segment is undergoing a "supermarket revolution," again with the lead in change in China. In most cases the government is not playing a direct role in the market, but enabling this transformation through infrastructural investment. The transformation appears to be improving food security for cities by reducing margins, offering lower consumer rice prices, and increasing quality and diversity of rice. This paper discusses findings derived from unique stacked surveys of all value chain segments in seven zones, more and less developed, around Bangladesh, China, India, and Vietnam.

  7. Pair separation of magnetic elements in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Giannattasio, F.; Berrilli, F.; Biferale, L.; Del Moro, D.; Sbragaglia, M.; Bellot Rubio, L.; Gošić, M.; Orozco Suárez, D.

    2014-09-01

    The dynamic properties of the quiet Sun photosphere can be investigated by analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic elements). By using 25 h-long Hinode magnetograms at high spatial resolution (0.3 arcsec), we tracked 68 490 magnetic element pairs within a supergranular cell near the disk center. The computed pair separation spectrum, calculated on the whole set of particle pairs independently of their initial separation, points out what is known as a super-diffusive regime with spectral index γ = 1.55 ± 0.05, in agreement with the most recent literature, but extended to unprecedented spatial and temporal scales (from granular to supergranular). Furthermore, for the first time, we investigated here the spectrum of the mean square displacement of pairs of magnetic elements, depending on their initial separation r0. We found that there is a typical initial distance above (below) which the pair separation is faster (slower) than the average. A possible physical interpretation of such a typical spatial scale is also provided.

  8. High energy neutrinos from radio-quiet active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Alvarez-Muñiz, Jaime; Mészáros, Peter

    2004-12-01

    Most active galactic nuclei (AGN) lack prominent jets, and show modest radio emission and significant x-ray emission which arises mainly from the galactic core, very near the central black hole. We use a quantitative scenario of such core-dominated radio-quiet AGN, which attributes a substantial fraction of the x-ray emission to the presence of abortive jets involving the collision of gas blobs in the core. Here we investigate the consequences of the acceleration of protons in the shocks from such collisions. We find that protons will be accelerated up to energies above the pion photoproduction threshold on both the x rays and the UV photons from the accretion disk. The secondary charged pions decay, producing neutrinos. We predict significant fluxes of TeV-PeV neutrinos, and show that the AMANDA II detector is already constraining several important astrophysical parameters of these sources. Larger cubic kilometer detectors such as IceCube will be able to detect such neutrinos in less than one year of operation, or otherwise rule out this scenario.

  9. Supersonic quiet-tunnel development for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1995-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between February 1994 and February 1995. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) development of the Purdue Quiet-Flow Ludwieg Tube, (2) computational evaluation of the square nozzle concept for quiet-flow nozzles, and (3) measurement of the presence of early transition on the flat sidewalls of the NASA LaRC Mach 3.5 supersonic low-disturbance tunnel. Since items (1) and (2) are described in the final report for companion grant NAG1-1133, only item (3) is described here. A thesis addressing the development of square nozzles for high-speed, low-disturbance wind tunnels is included as an appendix.

  10. Promoting rest using a quiet time innovation in an adult neuroscience step down unit.

    PubMed

    Bergner, Tara

    2014-01-01

    Sleep and rest are fundamental for the restoration of energy needed to recuperate from illness, trauma and surgery. At present hospitals are too noisy to promote rest for patients. A literature search produced research that described how quiet time interventions addressing noise levels have met with positive patient and staff satisfaction, as well as creating a more peaceful and healing environment. In this paper, a description of the importance of quiet time and how a small butfeasible innovation was carried out in an adult neuroscience step down unit in a large tertiary health care facility in Canada is provided. Anecdotal evidence from patients, families, and staff suggests that quiet time may have positive effects for patients, their families, and the adult neuroscience step down unit staff Future research examining the effect of quiet time on patient, family and staff satisfaction and patient healing is necessary.

  11. Quiet zone within a seismic gap near western Nicaragua: Possible location of a future large earthquake

    USGS Publications Warehouse

    Harlow, D.H.; White, R.A.; Cifuentes, I.L.; Aburto, Q.A.

    1981-01-01

    A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone. Copyright ?? 1981 AAAS.

  12. What is the difference between radio-loud and radio-quiet quasi-stellar objects?

    NASA Technical Reports Server (NTRS)

    Hutchings, J. B.; Janson, T.; Neff, S. G.

    1989-01-01

    Measures of the nuclear and host galaxy luminosities and colors and a morphological discussion of the host galaxies are presented for a sample of low-redshift, high-luminosity, radio-quiet QSOs whose redshift and luminosity distribution matches that of a radio-loud sample previously discussed. Radio-quiet QSOs are found to reside in galaxies which are smaller, fainter, and redder than the host galaxies of radio-loud QSOs. These properties are generally consistent with the suggestion that radio-quiet QSOs are located in spiral-type galaxies and radio-loud QSOs are located in more elliptical-type galaxies. Significantly less evidence is found for tidal interactions among the radio-quiet objects, although they appear to reside in somewhat richer environments in terms of nearby companions.

  13. NASA F-15B #836 in flight with Quiet Spike attached

    NASA Image and Video Library

    2006-09-27

    NASA F-15B #836 in flight with Quiet Spike attached. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

  14. NASA F-15B #836 in flight with Quiet Spike attached

    NASA Image and Video Library

    2006-09-25

    NASA F-15B #836 in flight with Quiet Spike attached. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

  15. NASA F-15B #836 in flight with Quiet Spike attached

    NASA Image and Video Library

    2006-10-03

    NASA F-15B #836 in flight with Quiet Spike attached. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

  16. Gulfstream's Quiet Spike sonic boom mitigator being installed on NASA DFRC's F-15B testbed aircraft

    NASA Image and Video Library

    2006-04-17

    Gulfstream's Quiet Spike sonic boom mitigator being installed on NASA DFRC's F-15B testbed aircraft. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

  17. Magnetic Upflow Events in the Quiet-Sun Photosphere. I. Observations

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, S.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.

    2015-09-01

    Rapid magnetic upflows in the quiet-Sun photosphere were recently uncovered from both Sunrise/IMaX and Hinode/SOT observations. Here, we study magnetic upflow events (MUEs) from high-quality, high- (spatial, temporal, and spectral) resolution, and full Stokes observations in four photospheric magnetically sensitive Fe i lines centered at 5250.21, 6173.34, 6301.51, and 6302.50 Å acquired with the Swedish Solar Telescope (SST)/CRISP. We detect MUEs by subtracting in-line Stokes V signals from those in the far blue wing whose signal-to-noise ratio (S/N) ≥slant 7. We find a larger number of MUEs at any given time (2.0× {10}-2 arcsec-2), larger by one to two orders of magnitude, than previously reported. The MUEs appear to fall into four classes presenting different shapes of Stokes V profiles with (I) asymmetric double lobes, (II) single lobes, (III) double-humped (two same-polarity lobes), and (IV) three lobes (an extra blueshifted bump in addition to double lobes), of which less than half are single-lobed. We also find that MUEs are almost equally distributed in network and internetwork areas and they appear in the interior or at the edge of granules in both regions. Distributions of physical properties, except for horizontal velocity, of the MUEs (namely, Stokes V signal, size, line-of-sight velocity, and lifetime) are almost identical for the different spectral lines in our data. A bisector analysis of our spectrally resolved observations shows that these events host modest upflows and do not show a direct indication of the presence of supersonic upflows reported earlier. Our findings reveal that the numbers, types (classes), and properties determined for MUEs can strongly depend on the detection techniques used and the properties of the employed data, namely, S/Ns, resolutions, and wavelengths.

  18. EVIDENCE FOR QUASI-ISOTROPIC MAGNETIC FIELDS FROM HINODE QUIET-SUN OBSERVATIONS

    SciTech Connect

    Asensio Ramos, A.

    2009-08-20

    Some recent investigations of spectropolarimetric observations of the Zeeman effect in the Fe I lines at 630 nm carried out with the Hinode solar space telescope have concluded that the strength of the magnetic field vector in the internetwork regions of the quiet Sun is in the hG regime and that its inclination is predominantly horizontal. We critically reconsider the analysis of such observations and carry out a complete Bayesian analysis with the aim of extracting as much information as possible from them, including error bars. We apply the recently developed BAYES-ME code that carries out a complete Bayesian inference for Milne-Eddington atmospheres. The sampling of the posterior distribution function is obtained with a Markov Chain Monte Carlo scheme and the marginal distributions are analyzed in detail. The Kullback-Leibler divergence is used to study the extent to which the observations introduce new information in the inference process resulting in sufficiently constrained parameters. Our analysis clearly shows that only upper limits to the magnetic field strength can be inferred, with fields in the kG regime completely discarded. Furthermore, the noise level present in the analyzed Hinode observations induces a substantial loss of information for constraining the azimuth of the magnetic field. Concerning the inclination of the field, we demonstrate that some information is available to constrain it for those pixels with the largest polarimetric signal. The results also point out that the field in pixels with small polarimetric signals can be nicely reproduced in terms of a quasi-isotropic distribution.

  19. Submillimeter solar images from the JCMT

    SciTech Connect

    Kopp, G.; Lindsey, C.

    1992-01-01

    We present nearly full-disk, diffraction-limited solar images made at 350 and 850 [mu]m and at 1.3 mm from the 15 m James Clerk Maxwell Telescope on Mauna Kea. These wavelengths sample the thermal structure of the solar chromosphere at altitude from 500 to about 1500 km, providing a height-dependent diagnostic of the atmosphere. Filament channels and neutral lines are apparent in the submillimeter images, although filaments themselves are not clearly visible. The submillimeter images show plage approximately 20% brigher than the surrounding quiet Sun, while sunspot intensities are comparable to the quiet Sun. Circumfacules,' dark are similar to those seen in Ca 8542; comparison with Ca H and K may give estimates of the temperature and filing factor of the hot gas present in these probably bifurcated regions.

  20. Energy balance in solar and stellar chromospheres

    NASA Technical Reports Server (NTRS)

    Avrett, E. H.

    1981-01-01

    Net radiative cooling rates for quiet and active regions of the solar chromosphere and for two stellar chromospheres are calculated from corresponding atmospheric models. Models of chromospheric temperature and microvelocity distributions are derived from observed spectra of a dark point within a cell, the average sun and a very bright network element on the quiet sun, a solar plage and flare, and the stars Alpha Boo and Lambda And. Net radiative cooling rates due to the transitions of various atoms and ions are then calculated from the models as a function of depth. Large values of the net radiative cooling rate are found at the base of the chromosphere-corona transition region which are due primarily to Lyman alpha emission, and a temperature plateau is obtained in the transition region itself. In the chromospheric regions, the calculated cooling rate is equal to the mechanical energy input as a function of height and thus provides a direct constraint on theories of chromospheric heating.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  2. Simulations of Solar Jets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-02-01

    Formation of a coronal jet from twisted field lines that have reconnected with the ambient field. The colors show the radial velocity of the plasma. [Adapted from Szente et al. 2017]How do jets emitted from the Suns surface contribute to its corona and to the solar wind? In a recent study, a team of scientists performed complex three-dimensional simulations of coronal jets to answer these questions.Small ExplosionsCoronal jets are relatively small eruptions from the Suns surface, with heights of roughly 100 to 10,000 km, speeds of 10 to 1,000 km/s, and lifetimes of a few minutes to around ten hours. These jets are constantly present theyre emitted even from the quiet Sun, when activity is otherwise low and weve observed them with a fleet of Sun-watching space telescopes spanning the visible, extreme ultraviolet (EUV), and X-ray wavelength bands.A comparison of simulated observations based on the authors model (left panels) to actual EUV and X-ray observations of jets (right panels). [Szente et al. 2017]Due to their ubiquity, we speculate that these jets might contribute to heating the global solar corona (which is significantly hotter than the surface below it, a curiosity known as the coronal heating problem). We can also wonder what role these jets might play in driving the overall solar wind.Launching a JetLed by Judit Szente (University of Michigan), a team of scientists has explored the impact of coronal jets on the global corona and solar wind with a series of numerical simulations. Szente and collaborators used three-dimensional, magnetohydrodynamic simulations that provide realistic treatment of the solar atmosphere, the solar wind acceleration, and the complexities of heat transfer throughout the corona.In the authors simulations, a jet is initiated as a magnetic dipole rotates at the solar surface, winding up field lines. Magnetic reconnection between the twisted lines and the background field then launches the jet from the dense and hot solar

  3. Quiet Spike(TradeMark) Build-up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of Gulfstream Aerospace Corporation s Quiet Spike(TradeMark) hardware were recently completed on the NASA Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the F-15B airplane, along the fuselage centerline. For the Quiet Spike(TradeMark) experiment, however, instead of a centerline mounting, a relatively long forward-pointing boom was attached to the radar bulkhead of the F-15B airplane. The Quiet Spike(TradeMark) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets over land. The Quiet Spike(TradeMark) boom is a concept in which an aircraft s noseboom would be extended prior to supersonic acceleration. This morphing effectively lengthens the aircraft, thus reducing the peak sonic-boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, noncoalescing shocklets. Prior to flying the Quiet Spike(TradeMark) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TradeMark) modal characteristics and coupling effects with the F-15B airplane. However, due to the flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TradeMark) ready-for- flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This paper provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TradeMark) project which includes the test setup details, instrumentation layout, and modal results obtained in support of the structural dynamic modeling and flutter

  4. Characterizing Postural Sway during Quiet Stance Based on the Intermittent Control Hypothesis

    NASA Astrophysics Data System (ADS)

    Nomura, Taishin; Nakamura, Toru; Fukada, Kei; Sakoda, Saburo

    2007-07-01

    This article illustrates a signal processing methodology for the time series of postural sway and accompanied electromyographs from the lower limb muscles during quiet stance. It was shown that the proposed methodology was capable of identifying the underlying postural control mechanisms. A preliminary application of the methodology provided evidence that supports the intermittent control hypothesis alternative to the conventional stiffness control hypothesis during human quiet upright stance.

  5. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  6. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  7. The Aurora at Quiet Magnetospheric Conditions: Repeatability and Dipole Tilt Angle Dependence

    DTIC Science & Technology

    1993-03-01

    A tial to variation of the dipole tilt angle. Wu et al. [1991] images of the aurora borealis obtained by Polar BEAR at studied the substorm westward... Aurora at Quiet Magnetospheric Conditions: SRepeatability and Dipole Tilt Angle Dependence PE 62101F _PR 4643 6. AUTHCR(S) TA 11 I. Oznovich*, R.W...tilt angle at quiet magnetospheric conditions? In order to address these questions, northern hemisphere images of the aurora at 1356 A, obtained by

  8. Cosmic ray albedo gamma rays from the quiet sun

    NASA Technical Reports Server (NTRS)

    Seckel, D.; Stanev, T.; Gaisser, T. K.

    1992-01-01

    We estimate the flux of gamma-rays that result from collisions of high energy galactic cosmic rays with the solar atmosphere. An important aspect of our model is the propagation of cosmic rays through the magnetic fields of the inner solar systems. We use diffusion to model propagation down to the bottom of the corona. Below the corona we trace particle orbits through the photospheric fields to determine the location of cosmic ray interactions in the solar atmosphere and evolve the resultant cascades. For our nominal choice of parameters, we predict an integrated flux of gamma rays (at 1 AU) of F(E(sub gamma) greater than 100 MeV) approximately = 5 x 10(exp -8)/sq cm sec. This can be an order of magnitude above the galactic background and should be observable by the Energetic Gamma Ray experiment telescope (EGRET).

  9. A preliminary comparison of Na lidar and meteor radar zonal winds during quiet and sub-storm conditions

    NASA Astrophysics Data System (ADS)

    Grandhi, Kishore Kumar; Nesse Tyssøy, Hilde; Williams, Bifford P.; Stober, Gunter

    2017-04-01

    It is speculated that sufficiently large electric fields during geomagnetic disturbed conditions may decouple the meteor trail electron motions from the background neutral winds and leads to erroneous neutral wind estimation. As per our knowledge, the potential errors have never been reported. In the present case study, we have been using co-located meteor radar and sodium resonance lidar zonal wind measurements over Andenes (69.27oN,16.04oE) during intense sub storms in the declining phase of Jan 2005 solar proton event (21-22 Jan 2005). In total 14 hours of continuous measurements are available for the comparison, which covers both quiet and disturbed conditions. For comparison, the lidar zonal winds are averaged in meteor radar time and height bins. High cross correlations (˜0.8) are found in all height regions. The discrepancies can be explained in the light of differences in the observational volumes of the two instruments. Further, we extended the comparison to address the ionization impact on the meteor radar winds. For quiet hours, the observed meteor radar winds are quite consistent with lidar winds. While during the disturbed hours comparatively large differences are noticed at higher most altitudes. This might be due to ionization impact on meteor radar winds. At the present one event is not sufficient to make any consolidate conclusion. However, at least from this study we found some effect on the neutral wind measurements for the meteor radar. Further study with more co-located measurements are needed to test statistical significance of the result.

  10. Quiet eye facilitates sensorimotor preprograming and online control of precision aiming in golf putting.

    PubMed

    Causer, Joe; Hayes, Spencer J; Hooper, James M; Bennett, Simon J

    2017-02-01

    An occlusion protocol was used to elucidate the respective roles of preprograming and online control during the quiet eye period of golf putting. Twenty-one novice golfers completed golf putts to 6-ft and 11-ft targets under full vision or with vision occluded on initiation of the backswing. Radial error (RE) was higher, and quiet eye was longer, when putting to the 11-ft versus 6-ft target, and in the occluded versus full vision condition. Quiet eye durations, as well as preprograming, online and dwell durations, were longer in low-RE compared to high-RE trials. The preprograming component of quiet eye was significantly longer in the occluded vision condition, whereas the online and dwell components were significantly longer in the full vision condition. These findings demonstrate an increase in preprograming when vision is occluded. However, this was not sufficient to overcome the need for online visual control during the quiet eye period. These findings suggest the quiet eye period is composed of preprograming and online control elements; however, online visual control of action is critical to performance.

  11. Effect of companding on speech recognition in quiet and noise for listeners with ANSD.

    PubMed

    Narne, Vijaya Kumar; Barman, Animesh; Deepthi, M

    2014-02-01

    The present study assesses the effect of companding on speech perception in quiet and noise for listeners with auditory neuropathy spectrum disorder (ANSD). Speech perception was assessed using speech reception threshold in noise (SRTn) for sentences and consonant identification in quiet and at different signal-to-noise ratios (15, 10, 5, and 0 dB SNR). Ten ANSD listeners and normal-hearing listeners participated in the study. ANSD listeners required significantly higher SRTn when compared to the normal-hearing listeners. Companding reduced SRTn more significantly in listeners with ANSD, but for normal-hearing listeners there was only a marginal reduction. In the consonant identification task, ANSD listeners performed poorer than normal-hearing listeners in quiet and noise. Companding improved consonant identification in quiet and at 15 dB SNR for listeners with ANSD, whereas no improvement was observed in normal-hearing listeners. Results of the present study demonstrate that companding improved speech perception in quiet and noise for ANSD listeners. The amount of improvement is higher at higher SNRs. In normal-hearing listeners, companding showed marginal improvement in both quiet and noise. The findings are discussed for rehabilitation of ANSD listeners by hearing aids which incorporate the companding strategy.

  12. Measuring the CMB Polarization at 94 GHz with the QUIET Experiment

    NASA Astrophysics Data System (ADS)

    Monsalve, Raul

    2012-01-01

    The Q/U Imaging ExperimenT (QUIET) aims to limit or detect cosmic microwave background (CMB) divergence-free (B-mode) polarization from inflation. This talk is part 1 of a 3-talk series on QUIET. QUIET operated in the Chilean Atacama desert between August 2008 and December 2010. During its second season it observed with a 90-element W-band receiver at 94 GHz. QUIET's primary goal is the detection of the B-mode polarization of the CMB predicted by inflationary models. This is one of the great objectives of the current generation of cosmology experiments. In order to realize the extremely low signal levels necessary to detect B-mode polarization, QUIET has incorporated a number of novel design features that have combined to minimize systematic effects. Some of these include an all-enshrouding, absorbing ground screen, side-fed Dragonian optics, platelet arrays of corrugated feedhorns, low crosstalk septum polarizers, compact MMIC modules and a double demodulation scheme. The talk provides an overview of the science goals and a description of the instrument, scanning strategies and calibration techniques. It also presents a straightforward approach to extracting and understanding low level instrumental polarization which can ultimately hamper these types of measurements. The next talks will provide an overview of the two parallel pipelines used in the QUIET data analysis.

  13. Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1994-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between May 1990 and December 1994. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) the design, fabrication, and performance-evaluation of a new kind of quiet tunnel, a quiet-flow Ludweig tube; (2) the integration of preexisting codes for nozzle design, 2D boundary-layer computation, and transition-estimation into a single user-friendly package for quiet-nozzle design; and (3) the design and preliminary evaluation of supersonic nozzles with square cross-section, as an alternative to conventional quiet-flow nozzles. After a brief summary of (1), a description of (2) is presented. Published work describing (3) is then summarized. The report concludes with a description of recent results for the Tollmien-Schlichting and Gortler instability in one of the square nozzles previously analyzed.

  14. The 'Quiet Eye' and Motor Performance: A Systematic Review Based on Newell's Constraints-Led Model.

    PubMed

    Rienhoff, Rebecca; Tirp, Judith; Strauß, Bernd; Baker, Joseph; Schorer, Jörg

    2016-04-01

    The quiet eye (final fixation to a specific target prior to movement initiation) is a perceptual skill robustly associated with expertise and superior performance. The benefit of the phenomenon has been demonstrated in a range of sporting tasks. The mechanism(s) underpinning this phenomenon are much-debated and are associated with varying assumptions. This systematic review categorizes previous quiet eye research based on Newell's 1986 model of interacting constraints. Three electronic databases (Web of Science, Scopus, PubMed) were searched from inception until February 2015. Details of relevant studies were also obtained from one literature review and two book chapters. To frame the discussion of research evidence concerning the quiet eye, previous studies were evaluated based on a classification of manipulating performer, environment, and task constraints. Additionally, associative studies (without specific constraints), and interacting constraints (affecting more than one constraint) were considered. This review emphasizes that the quiet eye is beneficial for performing aiming tasks and that Newell's constraints model provides a useful framework for organizing knowledge in this area. Despite the robust research on the value of the quiet eye, several gaps in current knowledge exist regarding the mechanism of the quiet eye effect.

  15. Running quietly reduces ground reaction force and vertical loading rate and alters foot strike technique.

    PubMed

    Phan, Xuan; Grisbrook, Tiffany L; Wernli, Kevin; Stearne, Sarah M; Davey, Paul; Ng, Leo

    2017-08-01

    This study aimed to determine if a quantifiable relationship exists between the peak sound amplitude and peak vertical ground reaction force (vGRF) and vertical loading rate during running. It also investigated whether differences in peak sound amplitude, contact time, lower limb kinematics, kinetics and foot strike technique existed when participants were verbally instructed to run quietly compared to their normal running. A total of 26 males completed running trials for two sound conditions: normal running and quiet running. Simple linear regressions revealed no significant relationships between impact sound and peak vGRF in the normal and quiet conditions and vertical loading rate in the normal condition. t-Tests revealed significant within-subject decreases in peak sound, peak vGRF and vertical loading rate during the quiet compared to the normal running condition. During the normal running condition, 15.4% of participants utilised a non-rearfoot strike technique compared to 76.9% in the quiet condition, which was corroborated by an increased ankle plantarflexion angle at initial contact. This study demonstrated that quieter impact sound is not directly associated with a lower peak vGRF or vertical loading rate. However, given the instructions to run quietly, participants effectively reduced peak impact sound, peak vGRF and vertical loading rate.

  16. Solar wind helium enhancements following major solar flares

    NASA Technical Reports Server (NTRS)

    Hirshberg, J.

    1972-01-01

    The observations of solar wind helium enhancements following major solar flares are reviewed, and the hypothesis that helium enhancements often mark flare piston plasma is confirmed. Helium enhancements were observed during each of the three periods (March 1966, July 1966, August/September 1966) of major solar activity that occurred from October 1965 to October 1966. No enhancements were seen during the long quiet periods that occurred that year. At 1 AU, the helium-enhanced plasma pistons had slowed so that the velocity was 80 percent of the mean transit velocity, in general agreement with theoretical models of the propagation of flare disturbances. A qualitative model, in which the piston plasma is accelerated from the flare site deep in the corona, is discussed briefly. If the model is valid in general outline, the piston plasmas provide samples of material from the lower levels of the corona.

  17. Relationships between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-scales (Quiet-Network) on the Sun

    NASA Astrophysics Data System (ADS)

    Sangeetha, C. R.; Rajaguru, S. P.

    2016-06-01

    We derive horizontal fluid motions on the solar surface over large areas covering the quiet-Sun magnetic network from local correlation tracking of convective granules imaged in continuum intensity and Doppler velocity by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. From these we calculate the horizontal divergence, the vertical component of vorticity, and the kinetic helicity of fluid motions. We study the correlations between fluid divergence and vorticity, and between vorticity (kinetic helicity) and the magnetic field. We find that the vorticity (kinetic helicity) around small-scale fields exhibits a hemispherical pattern (in sign) similar to that followed by the magnetic helicity of large-scale active regions (containing sunspots). We identify this pattern to be a result of the Coriolis force acting on supergranular-scale flows (both the outflows and inflows), consistent with earlier studies using local helioseismology. Furthermore, we show that the magnetic fields cause transfer of vorticity from supergranular inflow regions to outflow regions, and that they tend to suppress the vortical motions around them when magnetic flux densities exceed about 300 G (from HMI). We also show that such an action of the magnetic fields leads to marked changes in the correlations between fluid divergence and vorticity. These results are speculated to be of importance to local dynamo action (if present) and to the dynamical evolution of magnetic helicity at the small-scale.

  18. Generalized similarity in finite range solar wind magnetohydrodynamic turbulence.

    PubMed

    Chapman, S C; Nicol, R M

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum--with turbulent fluctuations down by a factor of approximately 2 in power--provides a test of this invariance.

  19. Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence

    SciTech Connect

    Chapman, S. C.; Nicol, R. M.

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum - with turbulent fluctuations down by a factor of approx2 in power - provides a test of this invariance.

  20. Solar collection

    NASA Astrophysics Data System (ADS)

    Cole, S. I.

    1984-08-01

    Solar dishes, photovoltaics, passive solar building and solar hot water systems, Trombe walls, hot air panels, hybrid solar heating systems, solar grain dryers, solar greenhouses, solar hot water worhshops, and solar workshops are discussed. These solar technologies are applied to residential situations.

  1. Radio-loud and Radio-quiet QSOs

    NASA Astrophysics Data System (ADS)

    Kellermann, K. I.; Condon, J. J.; Kimball, A. E.; Perley, R. A.; Ivezić, Željko

    2016-11-01

    We discuss 6 GHz JVLA observations covering a volume-limited sample of 178 low-redshift (0.2< z< 0.3) optically selected quasi-stellar objects (QSOs). Our 176 radio detections fall into two clear categories: (1) about 20% are radio-loud QSOs (RLQs) with spectral luminosities of {L}6≳ {10}23.2 {{W}} {{Hz}}-1 that are primarily generated in the active galactic nucleus (AGN) responsible for the excess optical luminosity that defines a bona fide QSO; and (2) the remaining 80% that are radio-quiet QSOs (RQQs) that have {10}21≲ {L}6≲ {10}23.2 {{W}} {{Hz}}-1 and radio sizes ≲ 10 {kpc}, and we suggest that the bulk of their radio emission is powered by star formation in their host galaxies. “Radio-silent” QSOs ({L}6≲ {10}21 {{W}} {{Hz}}-1) are rare, so most RQQ host galaxies form stars faster than the Milky Way; they are not “red and dead” ellipticals. Earlier radio observations did not have the luminosity sensitivity of {L}6≲ {10}21 {{W}} {{Hz}}-1 that is needed to distinguish between such RLQs and RQQs. Strong, generally double-sided radio emission spanning \\gg 10 {kpc} was found to be associated with 13 of the 18 RLQ cores with peak flux densities of {S}{{p}}> 5 {mJy} {{beam}}-1 ({log}(L)≳ 24). The radio luminosity function of optically selected QSOs and the extended radio emission associated with RLQs are both inconsistent with simple “unified” models that invoke relativistic beaming from randomly oriented QSOs to explain the difference between RLQs and RQQs. Some intrinsic property of the AGNs or their host galaxies must also determine whether or not a QSO appears radio-loud.

  2. Principles underlying the organization of movement initiation from quiet stance.

    PubMed

    Brunt, D; Liu, S M; Trimble, M; Bauer, J; Short, M

    1999-10-01

    The purpose of this study was to determine common principles underlying the programming of movement initiation from quiet stance. Subjects were asked to initiate gait, step over a ruler, or to step over a 10 cm high obstacle at a self-paced speed and as fast as possible. The independent variables were initiation condition (gait initiation, stepping over a ruler or obstacle) and initiation speed (self-paced and as fast as possible). The dependent measures for the stance limb only were the latency between postural soleus (S(1)) EMG inhibition and tibialis anterior (TA) EMG onset, the duration of both TA and soleus (S(2)) activity following TA, duration and slope, impulse, and peak forces of the anterior-posterior (Fx) ground reaction force. Selected timing events were also monitored. Analysis of variance was used to determine main and interaction effects. The following results were obtained. (1) The interval from the inhibition of S(1) postural activity to the onset of TA remained invariant between all conditions. (2) The duration of TA increased and S(2) decreased with an increase in speed of initiation. There was no difference in TA and S(2) duration between the initiation conditions. (3) Time to heel-off remained invariant for all conditions. (4) Prior to heel-off all force variables increased with initiation speed but were similar between initiation conditions. After heel-off force variables were different between speeds and conditions being greater for fast speed and stepping over the obstacle. Two conclusions may be drawn from this study. First, the results indicate that gait initiation consists of two, highly coordinated motor programs. Heel-off of the stance limb is the division between these two programs. Second, our findings also suggest that gait initiation and stepping are governed by the same motor programs.

  3. Quiet eye training facilitates competitive putting performance in elite golfers.

    PubMed

    Vine, Samuel J; Moore, Lee J; Wilson, Mark R

    2011-01-01

    The aim of this study was to examine the effectiveness of a brief quiet eye (QE) training intervention aimed at optimizing visuomotor control and putting performance of elite golfers under pressure, and in real competition. Twenty-two elite golfers (mean handicap 2.7) recorded putting statistics over 10 rounds of competitive golf before attending training individually. Having been randomly assigned to either a QE training or Control group, participants were fitted with an Applied Science Laboratories Mobile Eye tracker and performed 20 baseline (pre-test) putts from 10 ft. Training consisted of video feedback of their gaze behavior while they completed 20 putts; however the QE-trained group received additional instructions related to maintaining a longer QE period. Participants then recorded their putting statistics over a further 10 competitive rounds and re-visited the laboratory for retention and pressure tests of their visuomotor control and putting performance. Overall, the results were supportive of the efficacy of the QE training intervention. QE duration predicted 43% of the variance in putting performance, underlying its critical role in the visuomotor control of putting. The QE-trained group maintained their optimal QE under pressure conditions, whereas the Control group experienced reductions in QE when anxious, with subsequent effects on performance. Although their performance was similar in the pre-test, the QE-trained group holed more putts and left the ball closer to the hole on missed putts than their Control group counterparts in the pressure test. Importantly, these advantages transferred to the golf course, where QE-trained golfers made 1.9 fewer putts per round, compared to pre-training, whereas the Control group showed no change in their putting statistics. These results reveal that QE training, incorporated into a pre-shot routine, is an effective intervention to help golfers maintain control when anxious.

  4. First STEREO observation of a quiet sun CME

    NASA Astrophysics Data System (ADS)

    Robbrecht, E.; Patsourakos, S.; Vourlidas, A.

    2008-12-01

    Streamer-blowouts form a particular class of CMEs characterized by a slow rise and swelling of the streamer that can last for days. While they are more massive than the average CME, their slow development complicates their association with features/activity in the low corona and hampers studies on their initiation mechanism(s). This paper reports on the first observation from 2 viewpoints of a streamer blowout CME. The event was observed by the SECCHI/COR2 A instrument as a typical flux-rope type CME, while a very faint partial halo was observed in COR2-B. The CME erupted from the east limb in the COR2 A field of view. EUVI-171 A images show a bright feature above the limb, traveling from the southern hemisphere towards the equator after which it slowly rises into the coronagraphic fields of view developing into the flux-rope structure CME. At the time of eruption the separation between the two STEREO spacecraft is sufficiently large (54 deg) to observe the source region face-on in STEREO-B. However, inspection of EUVI B data didn't reveal any particular source region, other than the quiet sun. No flaring activity could be related to the eruption. This observation shows unambiguously that a CME eruption does not necessarily have clear on-disk signature. Also it sheds light on the long-standing question of the necessity of having a flare for producing a CME. This result supplies strong constraints for CME initiation models. This type of observation could not have been achieved without the multi-viewpoint observations by STEREO.

  5. Feedforward ankle strategy of balance during quiet stance in adults

    PubMed Central

    Gatev, Plamen; Thomas, Sherry; Kepple, Thomas; Hallett, Mark

    1999-01-01

    We studied quiet stance investigating strategies for maintaining balance. Normal subjects stood with natural stance and with feet together, with eyes open or closed. Kinematic, kinetic and EMG data were evaluated and cross-correlated.Cross-correlation analysis revealed a high, positive, zero-phased correlation between anteroposterior motions of the centre of gravity (COG) and centre of pressure (COP), head and COG, and between linear motions of the shoulder and knee in both sagittal and frontal planes. There was a moderate, negative, zero-phased correlation between the anteroposterior motion of COP and ankle angular motion.Narrow stance width increased ankle angular motion, hip angular motion, mediolateral sway of the COG, and the correlation between linear motions of the shoulder and knee in the frontal plane. Correlations between COG and COP and linear motions of the shoulder and knee in the sagittal plane were decreased. The correlation between the hip angular sway in the sagittal and frontal planes was dependent on interaction between support and vision.Low, significant positive correlations with time lags of the maximum of cross-correlation of 250-300 ms were found between the EMG activity of the lateral gastrocnemius muscle and anteroposterior motions of the COG and COP during normal stance. Narrow stance width decreased both correlations whereas absence of vision increased the correlation with COP.Ankle mechanisms dominate during normal stance especially in the sagittal plane. Narrow stance width decreased the role of the ankle and increased the role of hip mechanisms in the sagittal plane, while in the frontal plane both increased.The modulation pattern of the lateral gastrocnemius muscle suggests a central program of control of the ankle joint stiffness working to predict the loading pattern. PMID:9882761

  6. Quiet eye training in a visuomotor control task.

    PubMed

    Causer, Joe; Holmes, Paul S; Williams, Andrew Mark

    2011-06-01

    Several researchers have reported the importance of maintaining a longer final fixation on the target (termed the quiet eye period, QE) before performing an aiming task. We present an innovative, perceptual training intervention intended to improve the efficiency of gaze behavior (i.e., QE) in shotgun shooting. A sample of 20 international-level skeet shooters were assigned equally to one of two ability-matched groups based on their pretest shooting scores. A perceptual training group participated in a four-step preshot routine alongside three video feedback sessions involving their own gaze behaviors and those of an expert model in an effort to positively influence QE behaviors. A control group received video feedback of performance but without the addition of feedback on QE behaviors. Participants completed pretests and posttests along with an 8-wk training intervention. Subjects of the perceptual training group significantly increased their mean QE duration (397 vs 423 ms), used an earlier onset of QE (257 vs 244 ms), and recorded higher shooting accuracy scores (62 vs 70%) from pretest to posttest. Participants in the perceptual training group significantly reduced gun barrel displacement and absolute peak velocity on the posttest compared with the pretest, although neither variable was overtly trained. A transfer test based on performance during competition indicated that perceptual training significantly improved shooting accuracy from before to after the intervention. No pretest to posttest differences were observed for the control group on the measures reported. The results demonstrate the effectiveness of QE training in improving shooting accuracy and developing a more efficient visuomotor control strategy.The findings have implications for future research on training visuomotor behaviors, attention, and gaze orientation during the performance of aiming tasks.

  7. Io's Sodium Clouds and Plasma Torus: Three Quiet Apparitions

    NASA Astrophysics Data System (ADS)

    Wilson, Jody; Mendillo, M.; Baumgardner, J.

    2007-10-01

    Ground-based observations of Io's sodium clouds from February 2005 to June 2007 indicate that Io was in an unusually quiet state of atmospheric escape. Simultaneous observations of the sulfur-ion plasma torus in that same period indicate that the torus has been gradually dimming, which is also consistent with below-average atmospheric escape rates from Io. The S+ torus was essentially undetectable in May 2007. Our goal in this 3-year project was to compare variability in the clouds and torus with observations of Io's volcanic infrared ``hot spots'' (e.g., Marchis et al. 2005) in order to track the flow of mass from Io's volcanoes into Jupiter's magnetosphere. Of particular interest was the 18-month cycle of Io's large volcano Loki (Rathbun et al. 2002, Mendillo et al. 2004), however it seems that Loki has settled into an unusually long-term quiescent state (Rathbun and Spencer, 2006). Thus, although we have been unable to monitor the month-to-month effects of the Loki cycle, we nonetheless have indirect evidence for Loki's long-term effects on Io's atmosphere and Jupiter's magnetosphere by observing their weak states when Loki is not actively contributing. This research is funded in part by NASA's Planetary Astronomy Program. Marchis et al., Keck AO survey of Io global volcanic activity between 2 and 5 microns, Icarus, 176, 96-122, 2005. Mendillo et al., Io's volcanic control of Jupiter's extended neutral clouds, Icarus, 170, 430-442, 2004. Rathbun, J.A. et al., Loki, Io: A periodic volcano, Geophysical Research Letters, 29, Issue 10, pp. 84-1, 2002. Rathbun, J.A. and J.R. Spencer, Loki, Io: New ground-based observations and a model describing the change from periodic overturn, Geophysical Research Letters, 33, Issue 17, 2006.

  8. Quiet eye predicts goaltender success in deflected ice hockey shots.

    PubMed

    Panchuk, Derek; Vickers, Joan N; Hopkins, Will G

    2017-02-01

    In interceptive timing tasks, long quiet eye (QE) durations at the release point, along with early tracking on the object, allow performers to couple their actions to the kinematics of their opponent and regulate their movements based on emergent information from the object's trajectory. We used a mobile eye tracker to record the QE of eight university-level ice hockey goaltenders of an equivalent skill level as they responded to shots that deflected off a board placed to their left or right, resulting in a trajectory with low predictability. QE behaviour was assessed using logistic regression and magnitude-based inference. We found that when QE onset occurred later in the shot (950 ± 580 ms, mean ± SD) there was an increase in the proportion of goals allowed (41% vs. 22%) compared to when QE onset occurred earlier. A shorter QE duration (1260 ± 630 ms) predicted a large increase in the proportion of goals scored (38% vs. 14%). More saves occurred when QE duration (2074 ± 47 ms) was longer. An earlier QE offset (2004 ± 66 ms) also resulted in a large increase in the number of goals allowed (37% vs. 11%) compared to a later offset (2132 ± 41 ms). Since an early, sustained QE duration contributed to a higher percentage of saves, it is important that coaches develop practice activities that challenge the goaltender's ability to fixate the puck early, as well as sustain a long QE fixation on the puck until after it is released from the stick.

  9. Solar Coronal Plumes and the Fast Solar Wind

    NASA Astrophysics Data System (ADS)

    Dwivedi, Bhola N.; Wilhelm, Klaus

    2015-03-01

    The spectral profiles of the coronal Ne viii line at 77 nm have different shapes in quiet-Sun regions and Coronal Holes (CHs). A single Gaussian fit of the line profile provides an adequate approximation in quiet-Sun areas, whereas, a strong shoulder on the long-wavelength side is a systematic feature in CHs. Although this has been noticed since 1999, no physical reason for the peculiar shape could be given. In an attempt to identify the cause of this peculiarity, we address three problems that could not be conclusively resolved, in a review article by a study team of the International Space Science Institute (ISSI) (Wilhelm et al. 2011): (1) The physical processes operating at the base and inside of plumes, as well as their interaction with the Solar Wind (SW). (2) The possible contribution of plume plasma to the fast SW streams. (3) The signature of the First-Ionization Potential (FIP) effect between plumes and inter-plume regions (IPRs). Before the spectroscopic peculiarities in IPRs and plumes in Polar Coronal Holes (PCHs) can be further investigated with the instrument Solar Ultraviolet Measurements of Emitted Radiation (SUMER) aboard the Solar and Heliospheric Observatory (SOHO), it is mandatory to summarize the results of the review to place the spectroscopic observations into context. Finally, a plume model is proposed that satisfactorily explains the plasma flows up and down the plume field lines and leads to the shape of the neon line in PCHs.

  10. Solar flares controlled by helicity conservation

    NASA Technical Reports Server (NTRS)

    Gliner, Erast B.; Osherovich, Vladimir A.

    1995-01-01

    The energy release in a class of solar flares is studied on the assumption that during burst events in highly conducting plasma the magnetic helicity of plasma is approximately conserved. The available energy release under a solar flare controlled by the helicity conservation is shown to be defined by the magnetic structure of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominences; the discontinuation of the reconnection of magnetic lines long before the complete reconnection of participated fields occurs; the existence of quiet prominences which, in spite of their usual optical appearance, do not initiate any flare events; the small energy release under a solar flare in comparison with the stockpile of magnetic energy in surrounding fields. The predicted scale of the energy release is in a fair agreement with observations.

  11. Solar flares controlled by helicity conservation

    NASA Technical Reports Server (NTRS)

    Gliner, Erast B.; Osherovich, Vladimir A.

    1995-01-01

    The energy release in a class of solar flares is studied on the assumption that during burst events in highly conducting plasma the magnetic helicity of plasma is approximately conserved. The available energy release under a solar flare controlled by the helicity conservation is shown to be defined by the magnetic structure of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominences; the discontinuation of the reconnection of magnetic lines long before the complete reconnection of participated fields occurs; the existence of quiet prominences which, in spite of their usual optical appearance, do not initiate any flare events; the small energy release under a solar flare in comparison with the stockpile of magnetic energy in surrounding fields. The predicted scale of the energy release is in a fair agreement with observations.

  12. A new approach to the long-term reconstruction of the solar irradiance leads to large historical solar forcing

    NASA Astrophysics Data System (ADS)

    Shapiro, A. I.; Schmutz, W.; Rozanov, E.; Schoell, M.; Haberreiter, M.; Shapiro, A. V.; Nyeki, S.

    2011-05-01

    Context. The variable Sun is the most likely candidate for the natural forcing of past climate changes on time scales of 50 to 1000 years. Evidence for this understanding is that the terrestrial climate correlates positively with the solar activity. During the past 10 000 years, the Sun has experienced the substantial variations in activity and there have been numerous attempts to reconstruct solar irradiance. While there is general agreement on how solar forcing varied during the last several hundred years - all reconstructions are proportional to the solar activity - there is scientific controversy on the magnitude of solar forcing. Aims: We present a reconstruction of the total and spectral solar irradiance covering 130 nm-10 μm from 1610 to the present with an annual resolution and for the Holocene with a 22-year resolution. Methods: We assume that the minimum state of the quiet Sun in time corresponds to the observed quietest area on the present Sun. Then we use available long-term proxies of the solar activity, which are 10Be isotope concentrations in ice cores and 22-year smoothed neutron monitor data, to interpolate between the present quiet Sun and the minimum state of the quiet Sun. This determines the long-term trend in the solar variability, which is then superposed with the 11-year activity cycle calculated from the sunspot number. The time-dependent solar spectral irradiance from about 7000 BC to the present is then derived using a state-of-the-art radiation code. Results: We derive a total and spectral solar irradiance that was substantially lower during the Maunder minimum than the one observed today. The difference is remarkably larger than other estimations published in the recent literature. The magnitude of the solar UV variability, which indirectly affects the climate, is also found to exceed previous estimates.We discuss in detail the assumptions that lead us to this conclusion. Appendix is only available in electronic form at http://www.aanda.org

  13. Laboratory studies in ultraviolet solar physics

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.; Kohl, J. L.; Gardner, L. D.; Raymond, J. C.; Smith, P. L.

    1991-01-01

    The research activity comprised the measurement of basic atomic processes and parameters which relate directly to the interpretation of solar ultraviolet observations and to the development of comprehensive models of the component structures of the solar atmosphere. The research was specifically directed towards providing the relevant atomic data needed to perform and to improve solar diagnostic techniques which probe active and quiet portions of the solar chromosphere, the transition zone, the inner corona, and the solar wind acceleration regions of the extended corona. The accuracy with which the physical conditions in these structures can be determined depends directly on the accuracy and completeness of the atomic and molecular data. These laboratory data are used to support the analysis programs of past and current solar observations (e.g., the Orbiting solar Observatories, the Solar Maximum Mission, the Skylab Apollo Telescope Mount, and the Naval Research Laboratory's rocket-borne High Resolution Telescope and Spectrograph). In addition, we attempted to anticipate the needs of future space-borne solar studies such as from the joint ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Our laboratory activities stressed two categories of study: (1) the measurement of absolute rate coefficients for dielectronic recombination and electron impact excitation; and (2) the measurement of atomic transition probabilities for solar density diagnostics. A brief summary of the research activity is provided.

  14. Solar wind ion precipitation on Mars

    NASA Astrophysics Data System (ADS)

    Stenberg, Gabriella; Dieval, Catherine; Nilsson, Hans; Barabash, Stas; Futaana, Yoshifumi

    2013-04-01

    Solar wind ions (protons and alpha-particles) frequently precipitate onto the atmosphere of Mars. The precipitating particles contribute to the energy and matter flux into the ionosphere. The main reason for the solar-wind precipitation is likely the large gyroradii of hot particles in the magnetosheath compared to the size of the induced magnetosphere/magnetic barrier. Precipitating particles may modify the composition of the neutral atmosphere. As an example solar wind alpha-particles have been suggested to be an important source of neutral helium in the Martian atmosphere. We use ion data from the ASPERA-3 instrument onboard Mars Express to estimate the net transfer of energy and matter from the solar wind to the atmosphere. Our results indicate that the Martian ionosphere is better protected from penetrating solar wind ions than previously thought, at least during solar minimum conditions. In addition, our findings suggest that the contribution of solar wind alpha-particles to the helium balance of the atmosphere is smaller than expected. We also compare the ion precipitation during periods of quiet solar wind conditions and periods of solar wind pressure pulses. We show that the occurrence frequency of precipitation events is reduced by a factor 2-3 during periods when a solar wind pressure pulse reaches Mars, suggesting that the during this time the magnetic barrier becomes thicker in terms of solar wind ion gyroradii, making it more difficult for ions to precipitate.

  15. High speed magnetized flows in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Quintero Noda, C.; Borrero, J. M.; Orozco Suárez, D.; Ruiz Cobo, B.

    2014-09-01

    Context. We analyzed spectropolarimetric data recorded with Hinode/SP in quiet-Sun regions located at the disk center. We found single-lobed Stokes V profiles showing highly blue- and red-shifted signals. Oftentimes both types of events appear to be related to each other. Aims: We aim to set constraints on the nature and physical causes of these highly Doppler-shifted signals, as well as to study their spatial distribution, spectropolarimetric properties, size, and rate of occurrence. Also, we plan to retrieve the variation of the physical parameters with optical depth through the photosphere. Methods: We have examined the spatial and polarimetric properties of these events using a variety of data from the Hinode spacecraft. We have also inferred the atmospheric stratification of the physical parameters by means of the inversion of the observed Stokes profiles employing the Stokes Inversion based on Response functions (SIR) code. Finally, we analyzed their evolution using a time series from the same instrument. Results: Blue-shifted events tend to appear over bright regions at the edge of granules, while red-shifted events are seen predominantly over dark regions on intergranular lanes. Large linear polarization signals can be seen in the region that connects them. The magnetic structure inferred from the time series revealed that the structure corresponds to a Ω-loop, with one footpoint always over the edge of a granule and the other inside an intergranular lane. The physical parameters obtained from the inversions of the observed Stokes profiles in both events show an increase with respect to the Harvard-Smithonian reference atmosphere in the temperature at log τ500 ∈ (-1, -3) and a strong magnetic field, B ≥ 1 kG, at the bottom of the atmosphere that quickly decreases upward until vanishing at log τ500 ≈ -2. In the blue-shifted events, the LOS velocities change from upflows at the bottom to downflows at the top of the atmosphere. Red-shifted events

  16. Mass composition and dynamics in quiet sun prominences

    NASA Astrophysics Data System (ADS)

    Kilper, Gary K.

    2009-06-01

    Solar prominences are transient phenomena in the solar atmosphere that display highly dynamic activity and can result in dramatic eruptions, ejecting a large amount of material into the heliosphere. The dynamics of the prominence plasma reveal information about its interaction with the magnetic field of the prominence, while the eruptions are associated with coronal mass ejections, which greatly affect space weather near Earth and throughout the solar system. My research on these topics was conducted via observational analyses of the partially-ionized prominence material, its composition, and the dynamics over time in prominences that range in activity from quiescent to highly active. The main results are evidence that (1) in quiescent prominences, neutral He is located more in the lower part of the structure, (2) a higher level of activity in prominences is related to a mixing of the material, and (3) an extended period of high activity and mixing occurs prior to eruptions, possibly due to mass loading. In addition, innovative modifications to analytical techniques led to measurements of the material's mass, composition, and small-scale dynamics.

  17. F15B-Quiet Spike Aeroservoelastic Flight Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.

    2007-01-01

    Airframe structural morphing technologies designed to mitigate sonic boom strength are being developed by Gulfstream Aerospace Corporation (GAC). Among these technologies is a concept in which an aircraft's frontend would be extended prior to supersonic acceleration. This morphing would effectively lengthen the vehicle, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. This combination of boom shaping techniques is predicted to transform the classic, high-impulse N-wave pattern typically generated by an aircraft traveling at supersonic speed into a signature more closely resembling a sinusoidal wave with a greatly reduced perceived loudness. 'QuietSpike' is GAC's nomenclature for its recently patented front-end vehicle morphing arrangement. The ability of Quiet Spike to effectively shape a vehicle's far- field sonic boom signature is highly dependent on the area distribution characteristics of the aircraft. The full aeroacoustic benefits of front-end morphing at farfield are only possible when the QuietSpike article and vehicle configuration are designed in consideration of each other. Adding QuietSpike technology to the airframe of an existing, non-boom-optimized supersonic vehicle is unlikely to result in an improved far-field signature due to the generally over-powering influence of wing- and inlet-generated shocks. Therefore, it is generally recognized within NASA and the industry that a clean-sheet vehicle design is required to demonstrate the theoretically predicted far-field aeroacoustic benefits of QuietSpike type morphing and other boom- mitigating concepts. NASA's Aeronautics Research Mission Directorate (ARMD) Supersonics Division has placed increased priority on near-term development and flight-testing of such a vehicle. To help achieve this objective, static and dynamic aerostructural proof-of-concept testing was considered a prudent step

  18. F15B-Quiet Spike Aeroservoelastic Flight Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.

    2007-01-01

    Airframe structural morphing technologies designed to mitigate sonic boom strength are being developed by Gulfstream Aerospace Corporation (GAC). Among these technologies is a concept in which an aircraft's frontend would be extended prior to supersonic acceleration. This morphing would effectively lengthen the vehicle, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. This combination of boom shaping techniques is predicted to transform the classic, high-impulse N-wave pattern typically generated by an aircraft traveling at supersonic speed into a signature more closely resembling a sinusoidal wave with a greatly reduced perceived loudness. 'QuietSpike' is GAC's nomenclature for its recently patented front-end vehicle morphing arrangement. The ability of Quiet Spike to effectively shape a vehicle's far- field sonic boom signature is highly dependent on the area distribution characteristics of the aircraft. The full aeroacoustic benefits of front-end morphing at farfield are only possible when the QuietSpike article and vehicle configuration are designed in consideration of each other. Adding QuietSpike technology to the airframe of an existing, non-boom-optimized supersonic vehicle is unlikely to result in an improved far-field signature due to the generally over-powering influence of wing- and inlet-generated shocks. Therefore, it is generally recognized within NASA and the industry that a clean-sheet vehicle design is required to demonstrate the theoretically predicted far-field aeroacoustic benefits of QuietSpike type morphing and other boom- mitigating concepts. NASA's Aeronautics Research Mission Directorate (ARMD) Supersonics Division has placed increased priority on near-term development and flight-testing of such a vehicle. To help achieve this objective, static and dynamic aerostructural proof-of-concept testing was considered a prudent step

  19. Flight Testing of the Gulfstream Quiet Spike(TradeMark) on a NASA F-15B

    NASA Technical Reports Server (NTRS)

    Smolka, James W.; Cowert, Robert A.; Molzahn, Leslie M.

    2007-01-01

    Gulfstream Aerospace has long been interested in the development of an economically viable supersonic business jet (SBJ). A design requirement for such an aircraft is the ability for unrestricted supersonic flight over land. Although independent studies continue to substantiate that a market for a SBJ exists, regulatory and public acceptance challenges still remain for supersonic operation over land. The largest technical barrier to achieving this goal is sonic boom attenuation. Gulfstream's attention has been focused on fundamental research into sonic boom suppression for several years. This research was conducted in partnership with the NASA Aeronautics Research Mission Directorate (ARMD) supersonic airframe cruise efficiency technical challenge. The Quiet Spike, a multi-stage telescopic nose boom and a Gulfstream-patented design (references 1 and 2), was developed to address the sonic boom attenuation challenge and validate the technical feasibility of a morphing fuselage. The Quiet Spike Flight Test Program represents a major step into supersonic technology development for sonic boom suppression. The Gulfstream Aerospace Quiet Spike was designed to reduce the sonic boom signature of the forward fuselage for an aircraft flying at supersonic speeds. In 2004, the Quiet Spike Flight Test Program was conceived by Gulfstream and NASA to demonstrate the feasibility of sonic boom mitigation and centered on the structural and mechanical viability of the translating test article design. Research testing of the Quiet Spike consisted of numerous ground and flight operations. Each step in the process had unique objectives, and involved numerous test team members from the NASA Dryden Flight Research Center (DFRC) and Gulfstream Aerospace. Flight testing of the Quiet Spike was conducted at the NASA Dryden Flight Research Center on an F-15B aircraft from August, 2006, to February, 2007. During this period, the Quiet Spike was flown at supersonic speeds up to Mach 1.8 at the

  20. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    SciTech Connect

    Pavan, J.; Gaelzer, R.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F. E-mail: rudi@ufpel.edu.br E-mail: yoonp@umd.edu

    2013-06-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  1. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    NASA Technical Reports Server (NTRS)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

    2013-01-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  2. The role of periodicity in perceiving speech in quiet and in background noise.

    PubMed

    Steinmetzger, Kurt; Rosen, Stuart

    2015-12-01

    The ability of normal-hearing listeners to perceive sentences in quiet and in background noise was investigated in a variety of conditions mixing the presence and absence of periodicity (i.e., voicing) in both target and masker. Experiment 1 showed that in quiet, aperiodic noise-vocoded speech and speech with a natural amount of periodicity were equally intelligible, while fully periodic speech was much harder to understand. In Experiments 2 and 3, speech reception thresholds for these targets were measured in the presence of four different maskers: speech-shaped noise, harmonic complexes with a dynamically varying F0 contour, and 10 Hz amplitude-modulated versions of both. For experiment 2, results of experiment 1 were used to identify conditions with equal intelligibility in quiet, while in experiment 3 target intelligibility in quiet was near ceiling. In the presence of a masker, periodicity in the target speech mattered little, but listeners strongly benefited from periodicity in the masker. Substantial fluctuating-masker benefits required the target speech to be almost perfectly intelligible in quiet. In summary, results suggest that the ability to exploit periodicity cues may be an even more important factor when attempting to understand speech embedded in noise than the ability to benefit from masker fluctuations.

  3. Older Individuals Meeting Medicare Cochlear Implant Candidacy Criteria in Noise but Not in Quiet: Are These Patients Improved by Surgery?

    PubMed

    Mudery, Jordan A; Francis, Ross; McCrary, Hilary; Jacob, Abraham

    2017-02-01

    To investigate postoperative hearing outcomes in older patients who qualified for cochlear implant (CI) by Medicare criteria using AZBio sentence tests performed in noise but not in quiet. Review of patient records. University-based otology/neurotology practice. The senior author performed 136 CI between January 2013 and September 2015. Starting in 2013, CI candidacy evaluation included AZBio sentence tests performed in quiet and noise. For the current study, older patients with preoperative AZBio scores greater than 40% in quiet but less than 40% in noise (+10 or +5 dB signal to noise ratio [SNR]) and follow up >/=6 months were included. Cochlear implantation in one ear. Pre- versus postoperative AZBio sentence test scores. Fifteen patients with an average age of 73 years (range, 59-91) met inclusion criteria. Preoperative AZBio scores for the implanted ear averaged 47% points in quiet and 9% points in noise (+10 or +5 dB SNR). Preoperative bilateral AZBio scores averaged 70% points in quiet and 24% points in noise (+10 or +5 dB SNR). Postoperative AZBio scores for the implanted ear improved an average of 71% points in quiet and 51% points in noise. Postoperative bilateral hearing improved 23% points in quiet and 27% points in noise. All patients undergoing CI candidacy testing should be tested in both quiet and noise conditions. For those who qualify only in noise, our results demonstrate that cochlear implantation typically improves hearing both in quiet and noise.

  4. Solar astronomy

    NASA Technical Reports Server (NTRS)

    Rosner, Robert; Noyes, Robert; Antiochos, Spiro K.; Canfield, Richard C.; Chupp, Edward L.; Deming, Drake; Doschek, George A.; Dulk, George A.; Foukal, Peter V.; Gilliland, Ronald L.

    1991-01-01

    An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research.

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

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, J.

    2015-12-01

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

  6. Flow and quiet eye: the role of attentional control in flow experience.

    PubMed

    Harris, David J; Vine, Samuel J; Wilson, Mark R

    2017-02-25

    This report was designed to investigate the role of effective attention control in flow states, by developing an experimental approach to the study of flow. A challenge-skill balance manipulation was applied to self-paced netball and basketball shooting tasks, with point of gaze recorded through mobile eye tracking. Quiet eye was used to index optimal control of visual attention. While the experimental manipulation was found to have no effect, quiet eye was associated with the experience of flow. Furthermore, mediation revealed an indirect effect of quiet eye on performance through flow experience. This study provides initial evidence that flow may be preceded by changes in visual attention, suggesting that further investigation of visual attention may elucidate the cognitive mechanisms behind flow experience.

  7. Effects of electrical noise to a knee joint on quiet bipedal stance and treadmill walking.

    PubMed

    Kimura, T; Taki, C; Shiozawa, N; Kouzaki, M

    2013-01-01

    The present study assessed whether an unperceivable, noise-like electrical stimulation of a knee joint enhances the stability of quiet bipedal stance and treadmill walking in young subjects. The results showed that the slow postural sway measures in quiet bipedal stance were significantly reduced by the electrical noise (P<0.05). In the treadmill walking, low frequency component (below 1 Hz) of mediolateral acceleration, measured at the third lumbar vertebra, significantly decreased with the electrical noise (P<0.05), while there were no changes in the anteroposterior and vertical directions. These results indicate that the electrical noise to a knee joint can be applied to enhance postural control in quiet bipedal stance and treadmill walking.

  8. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1991-01-01

    Laminar-turbulent transition in high speed boundary layers is a complicated problem which is still poorly understood, partly because of experimental ambiguities caused by operating in noisy wind tunnels. The NASA Langley experience with quiet tunnel design has been used to design a quiet flow tunnel which can be constructed less expensively. Fabrication techniques have been investigated, and inviscid, boundary layer, and stability computer codes have been adapted for use in the nozzle design. Construction of such a facility seems feasible, at a reasonable cost. Two facilities have been proposed: a large one, with a quiet flow region large enough to study the end of transition, and a smaller and less expensive one, capable of studying low Reynolds number issues such as receptivity. Funding for either facility remains to be obtained, although key facility elements have been obtained and are being integrated into the existing Purdue supersonic facilities.

  9. The influence of quiet eye training and pressure on attention and visuo-motor control.

    PubMed

    Vine, Samuel J; Wilson, Mark R

    2011-03-01

    The aim of this study was to examine the efficacy of an intervention designed to train effective visual attentional control (quiet eye-training) for a far aiming skill, and determine whether such training protected against attentional disruptions associated with performing under pressure. Sixteen novice participants wore a mobile eye-tracker to assess their visual attentional control (quiet eye) during the completion of 520 basketball free throws carried out over 8 days. They first performed 40 pre-test free throws and were randomly allocated into a quiet eye (QE) training or Control group (technical instruction only). Participants then performed 360 free throws during a training period and a further 120 test free throws under conditions designed to manipulate the level of anxiety experienced. The QE trained group maintained more effective visual attentional control and performed significantly better in the pressure test compared to the Control group, providing support for the efficacy of attentional training for visuo-motor skills.

  10. Q/U Imaging Experiment (QUIET): a ground-based probe of cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Buder, Immanuel

    2010-07-01

    QUIET is an experimental program to measure the polarization of the Cosmic Microwave Background (CMB) radiation from the ground. Previous CMB polarization data have been used to constrain the cosmological parameters that model the history of our universe. The exciting target for current and future experiments is detecting and measuring the faint polarization signals caused by gravity waves from the inflationary epoch which occurred < 10-30 s after the Big Bang. QUIET has finished an observing season at 44 GHz (Q-Band); observing at 95 GHz (W-Band) is ongoing. The instrument incorporates several technologies and approaches novel to CMB experiments. We describe the observing strategy, optics design, detector technology, and data acquisition. These systems combine to produce a polarization sensitivity of 64 (57) μK for a 1 s exposure of the Phase I Q (W) Band array. We describe the QUIET Phase I instrument and explain how systematic errors are reduced and quantified.

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

    NASA Astrophysics Data System (ADS)

    Tindale, E.; Chapman, S. C.

    2016-06-01

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

  12. Improvement of Quiet Standing Balance in Patients with Wallenberg Syndrome after Rehabilitation

    PubMed Central

    Na, Eun Hye; Han, Soo Jeong

    2011-01-01

    Objective To evaluate quiet standing balance of patients with Wallenberg syndrome before and after rehabilitation. Method Six patients with Wallenberg syndrome were enrolled within one month after being affected by an infarct of the lateral medulla. Quiet standing balance was assessed using posturography with eyes open and closed. The assessment was repeated after the patients had undergone rehabilitation treatment for three to nine months, and the results of the two assessments were compared. Results The quiet standing balance evaluation was performed by measurement of center of pressure (CoP) movement. In the initial test, the mean scores of mediolateral and anteroposterior speed, velocity movement, mediolateral and anteroposterior extent of CoP were all high, indicating impairments of quiet standing balance in the patients. After rehabilitation treatment, the anteroposterior speed and extent, the mediolateral speed and extent, and velocity moment of CoP showed statistically significant reductions in the eyes open condition (p<0.05), and the anteroposterior speed and extent and velocity moment of CoP had decreased in the eyes closed condition (p<0.05). Mediolateral speed and extent of CoP in the eyes closed condition had also decreased, but the reduction was not statistically significant. Conclusion This study demonstrated improvements of quiet standing balance, especially anteroposterior balance, in patients with Wallenberg syndrome following rehabilitation. We suggest that balance training is important in the rehabilitation of Wallenberg syndrome and that, as an objective measure of balance status, posturography is useful in the assessment of quiet standing balance. PMID:22506207

  13. Earthquake aftereffects in the Equatorial Ionization Anomaly region under geomagnetic quiet and storm conditions

    NASA Astrophysics Data System (ADS)

    Gulyaeva, T. L.; Arikan, F.; Stanislawska, I.

    2017-07-01

    In addition to multi-scale spatio-temporal trends that shape the ionosphere variability, the ionosphere responds to the disturbances that are solar, geomagnetic and seismic in origin. In this study, post-seismic ionospheric disturbances are investigated retrospectively from 1999 to 2015 using two different sets of ionospheric maps of the F2 layer critical frequency, foF2. One set of foF2 maps is obtained by assimilating Global Ionospheric Maps (GIM) of Total Electron Content (TEC) into IRI-Plas model (IRI-Plas-foF2). Another set of hourly foF2 maps is obtained using PRIME-251 mapping technique (PRIME-foF2) by the assimilation of ionosonde foF2 data into IRI-CCIR model. The geomagnetic storms affecting the ionosphere are determined with relevant thresholds of geomagnetic AE, aa, ap, ap(τ) and Dst indices. It is observed that more than 60% of the earthquakes occur in the Equatorial Ionization Anomaly (EIA) region within the belt of geomagnetic latitudes ±40° N and geographic longitudes 90-190° E. The co-seismic foF2 disturbances, DfoF2, are identified for the cells of the map if an instant foF2 value is outside of pre-defined bounds of foF2 median (μ) and standard deviation (σ), μ ± 1σ, in the map fragment of 1000 km radius around the earthquake hypocenter. The results of positive ionospheric disturbances, DfoF2p, and negative disturbances, DfoF2n, in the EIA region during the 12 h after earthquake differ with respect to geomagnetic quiet and storm conditions, nighttime and daytime, magnitude and depth of the earthquake. The maximum spatial variability (for more than 50% of map cells in the vicinity of hypocenter) is observed with positive disturbances (DfoF2p) for the earthquakes that occurred during daytime at a depth of 70-300 km.

  14. Auroral forms that extend equatorward from the persistent midday aurora during geomagnetically quiet periods

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. V.; Carlson, H. C.; Heelis, R. A.

    2012-09-01

    Auroral forms (“crewcuts”) that extend equatorward from the geomagnetically east-west aligned persistent midday aurora have been characterized based on a survey of Svalbard 630.0-nm all-sky images from eight December solstice seasons. The 630.0-nm forms are directly related to a mix of precipitating magnetosheath and plasma sheet electrons embedded in a population of boundary layer ions, as observed by NOAA 6. The associated midday aurora lies at the equatorward edge of poleward velocity-dispersed cusp ‘ion plumes’ observed by DMSP F7 at 1000 magnetic local time. In this survey, crewcuts are found to occur for Kp≤3. Distinct in many salient ways (including dynamics, orientation and associated IMF polarity) from the poleward-moving auroral forms (PMAFs) associated with transient dayside merging, crewcuts represent a solar wind-magnetosphere interaction that is more characteristic of quiet geomagnetic conditions. Crewcuts are present on 44% of the days for which all-sky images are complete and observing conditions are clear ±1.5 h around geomagnetic noon. During these periods, crewcuts are observed during 10.6% of the minutes for which IMF data from ISEE 2 or IMP 8 are available. We derive from the data a simple set of IMF “search criteria” that maximize the likelihood of observing crewcuts around the December solstice. The IMF magnitude range for which crewcuts are most commonly observed is 3.5±0.5 nT (36%). The IMF GSM component ranges in which crewcuts are most commonly observed are: Bx=-3.5±0.5 nT (27%), By=-1.5±0.5 nT (25%), and Bz=0.5±0.5 nT (26%). The IMF clock angular ranges for which crewcuts are most commonly observed are -70°±10° and 90°±10° (both 21%). The IMF cone angular range for which crewcuts are most commonly observed is 12.5°±2.5° (28%). Considering these observations in the context of magnetic merging topologies, we suggest crewcuts observed at Svalbard are most likely to lie at the foot of overdraped field lines

  15. A description of the external and internal quiet daily variation currents at North American locations for a quiet-Sun year.

    USGS Publications Warehouse

    Campbell, W.H.

    1983-01-01

    An order 4, degree 12 spherical harmonic analysis of the smoothed quiet geomagnetic daily variations was used to separate the external and internal geomagnetic Sq field at North American locations for the quiet-Sun year, 1965. These fields were represented by a month-by-month display of equivalent current vortex systems with dominant, pre-noon foci. The focus reached 40o latitude near the June solstice and about 30o latitude near the December solstice. The daily range of Sq current amplitudes was largest in late July to early August and smallest in mid-December. Semi-annual variations of Sq currents dominated only the equatorial region. Daily maxima in mid-latitudes, occurred mostly near local noon in December to February and about 1 hr before noon in June to mid-October. -Author

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

  18. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen D.

    1991-01-01

    The main objectives of this work is to demonstrate the potential of a cryogenic adaptive nozzle to generate quiet (low disturbance) supersonic flow. A drive system was researched for the Fluid Mechanics Laboratory (FML) Laminar Flow Supersonic Wind Tunnel (LFSWT) using a pilot tunnel. A supportive effort for ongoing Proof of Concept (PoC) research leading to the design of critical components of the LFSWT was maintained. The state-of-the-art in quiet supersonic wind tunnel design was investigated. A supersonic research capability was developed within the FML.

  19. Operational evaluation of a proppeller test stand in the quiet flow facility at Langley Research Center

    NASA Technical Reports Server (NTRS)

    Block, P. J. W.

    1982-01-01

    Operational proof tests of a propeller test stand (PTS) in a quiet flow facility (QFF) are presented. The PTS is an experimental test bed for acoustic propeller research in the quiet flow environment of the QFF. These proof tests validate thrust and torque predictions, examine the repeatability of measurements on the PTS, and determine the effect of applying artificial roughness to the propeller blades. Since a thrusting propeller causes an open jet to contract, the potential flow core was surveyed to examine the magnitude of the contraction. These measurements are compared with predicted values. The predictions are used to determine operational limitations for testing a given propeller design in the QFF.

  20. Magnetic Signatures of Ionospheric and Magnetospheric Current Systems During Geomagnetic Quiet Conditions—An Overview

    NASA Astrophysics Data System (ADS)

    Olsen, Nils; Stolle, Claudia

    2016-09-01

    High-precision magnetic measurements taken by LEO satellites (flying at altitudes between 300 and 800 km) allow for studying the ionospheric and magnetospheric processes and electric currents that causes only weak magnetic signature of a few nanotesla during geomagnetic quiet conditions. Of particular importance for this endeavour are multipoint observations in space, such as provided by the Swarm satellite constellation mission, in order to better characterize the space-time-structure of the current systems. Focusing on geomagnetic quiet conditions, we provide an overview of ionospheric and magnetospheric sources and illustrate their magnetic signatures with Swarm satellite observations.

  1. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1990-01-01

    Since Ludwieg tubes have been around for many years, and NASA has already established the feasibility of creating quiet-flow wind tunnels, the major question addressed was the cost of the proposed facility. Cost estimates were obtained for major system components, and new designs which allowed fabrication at lower cost were developed. A large fraction of the facility cost comes from the fabrication of the highly polished quiet-flow supersonic nozzle. Methods for the design of this nozzle were studied at length in an attempt to find an effective but less expensive design. Progress was sufficient to show that a quality facility can be fabricated at a reasonable cost.

  2. A Review of Hypersonic Boundary Layer Stability Experiments in a Quiet Mach 6 Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Wilkinson, Stephen P.

    1997-01-01

    Three recent experimental studies of transition on cones with adverse pressure gradient produced by a flared afterbody and with the additive stability modifiers of wall cooling, angle of attack and bluntness are reviewed. All tests were conducted in a quiet Mach 6 wind tunnel. The dominant instability was found to be the second mode. For the cases examined with linear stability theory, the N factors at mode saturation were in the range of 8.5 to 11. Evidence of a combined second-mode/Gortler transition process was found. Mean, rms and spectral freestream data for the quiet facility is presented and the role of low frequency freestream noise is discussed.

  3. Solar sources of interplanetary southward Bz events responsible for major magnetic storms (1978-1979)

    NASA Technical Reports Server (NTRS)

    Tang, Frances; Tsurutani, Bruce T.; Smith, Edward J.; Gonzalez, Walter D.; Akasofu, Syun I.

    1989-01-01

    The solar sources of interplanetary southward Bz events responsible for major magnetic storms observed in the August 1978-December 1979 period were studied using a full complement of solar wind plasma and field data from ISEE 3. It was found that, of the ten major storms observed, seven were initiated by active region flares, and three were associated with prominence eruptions in solar quiet regions. Nine of the storms were associated with interplanetary shocks. However, a comparison of the solar events' characteristics and those of the resulting interplanetary shocks indicated that standard solar parameters did not correlate with the strengths of the resulting shocks at 1 AU.

  4. Solar sources of interplanetary southward Bz events responsible for major magnetic storms (1978-1979)

    NASA Technical Reports Server (NTRS)

    Tang, Frances; Tsurutani, Bruce T.; Smith, Edward J.; Gonzalez, Walter D.; Akasofu, Syun I.

    1989-01-01

    The solar sources of interplanetary southward Bz events responsible for major magnetic storms observed in the August 1978-December 1979 period were studied using a full complement of solar wind plasma and field data from ISEE 3. It was found that, of the ten major storms observed, seven were initiated by active region flares, and three were associated with prominence eruptions in solar quiet regions. Nine of the storms were associated with interplanetary shocks. However, a comparison of the solar events' characteristics and those of the resulting interplanetary shocks indicated that standard solar parameters did not correlate with the strengths of the resulting shocks at 1 AU.

  5. Solar Activity Predictions Based on Solar Dynamo Theories

    NASA Astrophysics Data System (ADS)

    Schatten, Kenneth H.

    2009-05-01

    We review solar activity prediction methods, statistical, precursor, and recently the Dikpati and the Choudhury groups’ use of numerical flux-dynamo methods. Outlining various methods, we compare precursor techniques with weather forecasting. Precursors involve events prior to a solar cycle. First started by the Russian geomagnetician Ohl, and then Brown and Williams; the Earth's field variations near solar minimum was used to predict the next solar cycle, with a correlation of 0.95. From the standpoint of causality, as well as energetically, these relationships were somewhat bizarre. One index used was the "number of anomalous quiet days,” an antiquated, subjective index. Scientific progress cannot be made without some suspension of disbelief; otherwise old paradigms become tautologies. So, with youthful naïveté, Svalgaard, Scherrer, Wilcox and I viewed the results through rose-colored glasses and pressed ahead searching for understanding. We eventually fumbled our way to explaining how the Sun could broadcast the state of its internal dynamo to Earth. We noted one key aspect of the Babcock-Leighton Flux Dynamo theory: the polar field at the end of a cycle serves as a seed for the next cycle's growth. Near solar minimum this field usually bathes the Earth, and thereby affects geomagnetic indices then. We found support by examining 8 previous solar cycles. Using our solar precursor technique we successfully predicted cycles 21, 22 and 23 using WSO and MWSO data. Pesnell and I improved the method using a SODA (SOlar Dynamo Amplitude) Index. In 2005, nearing cycle 23's minimum, Svalgaard and I noted an unusually weak polar field, and forecasted a small cycle 24. We discuss future advances: the flux-dynamo methods. As far as future solar activity, I shall let the Sun decide; it will do so anyhow.

  6. Coronal energy distribution and X-ray activity in the small scale magnetic field of the quiet sun

    NASA Technical Reports Server (NTRS)

    Habbal, S. R.

    1992-01-01

    The energy distribution in the small-scale magnetic field that pervades the solar surface, and its relationship to X-ray/coronal activity are discussed. The observed emission from the small scale structures, at temperatures characteristic of the chromosphere, transition region and corona, emanates from the boundaries of supergranular cells, within coronal bright points. This emission is characterized by a strong temporal and spatial variability with no definite pattern. The analysis of simultaneous, multiwavelength EUV observations shows that the spatial density of the enhanced as well as variable emission from the small scale structures exhibits a pronounced temperature dependence with significant maxima at 100,000 and 1,000,000 K. Within the limits of the spatial (1-5 arcsec) and temporal (1-5 min) resolution of data available at present, the observed variability in the small scale structure cannot account for the coroal heating of the quiet sun. The characteristics of their emission are more likely to be an indicator of the coronal heating mechanisms.

  7. VizieR Online Data Catalog: UV spectrum of the quiet Sun above the limb (Warren+, 2014)

    NASA Astrophysics Data System (ADS)

    Warren, H. P.; Ugarte-Urra, I.; Landi, E.

    2014-09-01

    First, we compare full-disk mosaics constructed by scanning the EIS slot over the Sun with irradiance observations made by the EUV Variability Experiment (EVE; Woods et al. 2012SoPh..275..115W) on the Solar Dynamics Observatory (SDO) mission. These comparisons provide a means of establishing the absolute calibration for EIS. Second, we combine extended EIS observations from above the limb in the quiet Sun with a simple temperature model to simultaneously determine the differential emission measure (DEM) distribution and the time-dependent changes to the effective areas that best fit all of the available spectral lines. In Figure 2 we show the average spectrum from an observation of seven consecutive runs of ELFULLCCDWSUMER. The observations began on 2007 November 4 19:12 and ended on the same date at 23:51 UT. The EIS field of view was centered at (990", -50") about 22" above the limb of the Sun. The central 129 pixels along the slit have been averaged over 38 exposures (11 exposures were corrupted in transmission to the ground) for a total of 4902 intensity measurements at each wavelength. Since each exposure is 300s, the spectrum represents 1470600 pixels of effective exposure time and allows weak lines at the ends of the detector to be measured. (1 data file).

  8. Coronal energy distribution and X-ray activity in the small scale magnetic field of the quiet sun

    NASA Technical Reports Server (NTRS)

    Habbal, S. R.

    1992-01-01

    The energy distribution in the small-scale magnetic field that pervades the solar surface, and its relationship to X-ray/coronal activity are discussed. The observed emission from the small scale structures, at temperatures characteristic of the chromosphere, transition region and corona, emanates from the boundaries of supergranular cells, within coronal bright points. This emission is characterized by a strong temporal and spatial variability with no definite pattern. The analysis of simultaneous, multiwavelength EUV observations shows that the spatial density of the enhanced as well as variable emission from the small scale structures exhibits a pronounced temperature dependence with significant maxima at 100,000 and 1,000,000 K. Within the limits of the spatial (1-5 arcsec) and temporal (1-5 min) resolution of data available at present, the observed variability in the small scale structure cannot account for the coroal heating of the quiet sun. The characteristics of their emission are more likely to be an indicator of the coronal heating mechanisms.

  9. Helioseismology with Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Löptien, Björn; Birch, Aaron C.; Gizon, Laurent; Schou, Jesper; Appourchaux, Thierry; Blanco Rodríguez, Julián; Cally, Paul S.; Dominguez-Tagle, Carlos; Gandorfer, Achim; Hill, Frank; Hirzberger, Johann; Scherrer, Philip H.; Solanki, Sami K.

    2015-12-01

    The Solar Orbiter mission, to be launched in July 2017, will carry a suite of remote sensing and in-situ instruments, including the Polarimetric and Helioseismic Imager (PHI). PHI will deliver high-cadence images of the Sun in intensity and Doppler velocity suitable for carrying out novel helioseismic studies. The orbit of the Solar Orbiter spacecraft will reach a solar latitude of up to 21∘ (up to 34∘ by the end of the extended mission) and thus will enable the first local helioseismology studies of the polar regions. Here we consider an array of science objectives to be addressed by helioseismology within the baseline telemetry allocation (51 Gbit per orbit, current baseline) and within the science observing windows (baseline 3×10 days per orbit). A particularly important objective is the measurement of large-scale flows at high latitudes (rotation and meridional flow), which are largely unknown but play an important role in flux transport dynamos. For both helioseismology and feature tracking methods convection is a source of noise in the measurement of longitudinally averaged large-scale flows, which decreases as T -1/2 where T is the total duration of the observations. Therefore, the detection of small amplitude signals (e.g., meridional circulation, flows in the deep solar interior) requires long observation times. As an example, one hundred days of observations at lower spatial resolution would provide a noise level of about three m/s on the meridional flow at 80∘ latitude. Longer time-series are also needed to study temporal variations with the solar cycle. The full range of Earth-Sun-spacecraft angles provided by the orbit will enable helioseismology from two vantage points by combining PHI with another instrument: stereoscopic helioseismology will allow the study of the deep solar interior and a better understanding of the physics of solar oscillations in both quiet Sun and sunspots. We have used a model of the PHI instrument to study its

  10. Quiet time F2-layer disturbances at geomagnetic equator

    NASA Astrophysics Data System (ADS)

    Depueva, A. Kh.; Mikhailov, A. V.; Depuev, V. Kh.

    2005-03-01

    Ionospheric F2- layer disturbances not related to geomagnetic activity (Q2 disturbances) were analyzed using all available NmF2 observations over Huancayo (American sector) and Kodaikanal (Indian sector) stations located at the proximity of geomagnetic equator. Both positive and negative Q disturbances were revealed, their amplitude being comparable to usual F2 layer storm effects. The occurrence of Q disturbances exhibit a systematic dependence on solar activity, season, and local time. The revealed morphology of Q disturbances at Huancayo can be explained by the observed at Jicamarca E×B vertical drifts. There are some differences between Huancayo and Kodaikanal Q disturbance morphological patterns that cannot be attributed to small differences in E×B vertical drifts in the two longitudinal sectors.

  11. A review of the Nimbus-7 ERB solar dataset

    NASA Technical Reports Server (NTRS)

    Kyle, H. L.; Hoyt, D. V.; Hickey, J. R.

    1994-01-01

    Fourteen years (November 16, 1978 through January 24, 1993) of Nimbus-7 total solar irradiance measurements have been made. The measured mean annual solar energy just outside of the Earth's atmosphere was about 0.1% (1.4 W per sq m) higher in the peak years of 1979 (cycle 21) and 1991 (cycle 22) than in the quiet Sun years of 1985/86. Comparison with shorter independent solar measurement sets and with empirical models qualitatively confirms the Nimbus-7 results. But these comparisons also raise questions of detail for future studies: in which years did the peaks actually occur and just how accurate are the models and the measurements?

  12. A review of the Nimbus-7 ERB solar dataset

    NASA Technical Reports Server (NTRS)

    Kyle, H. L.; Hoyt, D. V.; Hickey, J. R.

    1994-01-01

    Fourteen years (November 16, 1978 through January 24, 1993) of Nimbus-7 total solar irradiance measurements have been made. The measured mean annual solar energy just outside of the Earth's atmosphere was about 0.1% (1.4 W per sq m) higher in the peak years of 1979 (cycle 21) and 1991 (cycle 22) than in the quiet Sun years of 1985/86. Comparison with shorter independent solar measurement sets and with empirical models qualitatively confirms the Nimbus-7 results. But these comparisons also raise questions of detail for future studies: in which years did the peaks actually occur and just how accurate are the models and the measurements?

  13. Scale-free texture of the fast solar wind.

    PubMed

    Hnat, B; Chapman, S C; Gogoberidze, G; Wicks, R T

    2011-12-01

    The higher-order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically, scale by scale. We find a single global non-Gaussian scale-free behavior from minutes to over 5 h. This spans the signature of an inertial range of magnetohydrodynamic turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude fluctuations is an intrinsic component of the underlying texture of the solar wind and puts a strong constraint on any theory of solar corona and the heliosphere. Intriguingly, the magnetic field and velocity components show scale-dependent dynamic alignment outside of the inertial range.

  14. TURBULENT MAGNETIC FIELDS IN THE QUIET SUN: IMPLICATIONS OF HINODE OBSERVATIONS AND SMALL-SCALE DYNAMO SIMULATIONS

    SciTech Connect

    Pietarila Graham, Jonathan; Danilovic, Sanja; Schuessler, Manfred

    2009-03-10

    Using turbulent MHD simulations (magnetic Reynolds numbers up to {approx}8000) and Hinode observations, we study effects of turbulence on measuring the solar magnetic field outside active regions. First, from synthetic Stokes V profiles for the Fe I lines at 6301 and 6302 A, we show that a peaked probability distribution function (PDF) for observationally derived field estimates is consistent with a monotonic PDF for actual vertical field strengths. Hence, the prevalence of weak fields is greater than would be naively inferred from observations. Second, we employ the fractal self-similar geometry of the turbulent solar magnetic field to derive two estimates (numerical and observational) of the true mean vertical unsigned flux density. We also find observational evidence that the scales of magnetic structuring in the photosphere extend at least down to an order of magnitude smaller than 200 km: the self-similar power-law scaling in the signed measure from a Hinode magnetogram ranges (over two decades in length scales and including the granulation scale) down to the {approx}200 km resolution limit. From the self-similar scaling, we determine a lower bound for the true quiet-Sun mean vertical unsigned flux density of {approx}50 G. This is consistent with our numerically based estimates that 80% or more of the vertical unsigned flux should be invisible to Stokes V observations at a resolution of 200 km owing to the cancellation of signal from opposite magnetic polarities. Our estimates significantly reduce the order-of-magnitude discrepancy between Zeeman- and Hanle-based estimates.

  15. On the relationship between the postmidnight thermospheric equatorial mass anomaly and equatorial ionization anomaly under geomagnetic quiet conditions

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Liu, Libo; Zhao, Biqiang; Lei, Jiuhou; Wan, Weixing

    2011-12-01

    The equatorial mass anomaly (EMA) in the thermosphere and equatorial ionization anomaly (EIA) in the ionosphere are two interesting phenomena in low-equatorial latitude regions. Previous studies have shown that the EMA appears between 1000 and 2000 local time (LT) and its location of trough is aligned with dip equator, indicating the plausible role of the EIA structure in the development of EMA. In this report, we conducted a statistical study of the occurrence of postmidnight EMA and EIA on the basis of the CHAMP in situ measurements during 2002-2008. Our results revealed that clear EMA and EIA structures are sometimes visible in the postmidnight sector (0100-0600 LT) during geomagnetic quiet periods (Kp < 3). The postmidnight EMA is not necessarily accompanied by the EIA signature in both case study and statistics sense being distinct from the daytime situation. In addition, the occurrence rates of postmidnight EMA and EIA display contrasting behavior with respect to their local time, longitudinal and solar activity dependences. The highest occurrence rate for EMA is 8% at around 0300 LT, while the occurrence rate of the EIA decreases gradually from about 30% at around 2300 LT to ˜5% at 0600 LT. Longitudinal occurrence of postmidnight EIA presents a wave-like pattern; however, no salient feature appears for the longitudinal occurrence of EMA. Postmidnight EMA is more likely to occur at lower solar activity, whereas an opposite trend presents in the EIA. On the basis of above results, our findings imply that a simple EIA-EMA cause-effect relationship does not hold in the postmidnight sector.

  16. Limb-brightening curves of XUV transition zone lines in the quiet sun and in a polar coronal hole observed from Skylab

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Tousey, R.; Feldman, U.

    1975-01-01

    Solar limb-brightening curves are discussed for XUV spectral lines formed in the upper chromosphere and transition zone of a quiet region and a polar coronal hole. The spectra were recorded with a slit spectrograph on Skylab. The lines considered are emitted from ions formed within the temperature range from 10,000 to 220,000 K. The limb-brightening curves cover a region from -4 sec within the limb to +20 sec above it. The data from 0 sec to +20 sec are compared with predictions based on both homogeneous and inhomogeneous models of the transition zone. The limb-brightening curve of the O I line at 1355.6 A indicates that O I is formed in spicules. The limb brightening of the He II line at 1640.4 A is consistent with a temperature of formation between about 40,000 and 90,000 K for He II.

  17. State anxiety and visual attention: the role of the quiet eye period in aiming to a far target.

    PubMed

    Behan, Michael; Wilson, Mark

    2008-01-15

    In this study, we examined how individuals controlled their gaze behaviour during execution of a far aiming task and whether the functional relationship between perception and action was disrupted by increased anxiety. Twenty participants were trained on a simulated archery task, using a joystick to aim and shoot arrows at the target, and then competed in two counterbalanced experimental conditions designed to manipulate the anxiety they experienced. The specific gaze behaviour measured was the duration of the quiet eye period. As predicted, accuracy was affected by the duration of the quiet eye period, with longer quiet eye periods being associated with better performance. The manipulation of anxiety resulted in reductions in the duration of quiet eye. Our results show that the quiet eye period is sensitive to increases in anxiety and may be a useful index of the efficiency of visual orientation in aiming tasks.

  18. All Solar Minima are not Alike: Consequences at Earth

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Gibson, S. E.; de Toma, G.; Emery, B. A.; Onsager, T. G.; Sojka, J. J.; Thompson, B. J.

    2009-05-01

    New observations that were collected as part of the IHY Whole Heliosphere Campaign are changing our present understanding of solar quiet intervals and the solar minimum sun-Earth system. These observations indicate that significant differences in coronal hole distribution can occur at the Sun from one solar minimum to the next. The high-speed coronal hole wind is the primary source of space weather disturbances that perturb the Earth's upper atmosphere and create reactive species. The broad low-latitude coronal holes that developed this solar minimum produced strong, long-lived and recurring high-speed streams. This is in contrast to the weaker and more sporadic streams last solar minimum produced by narrow equatorward extensions from polar coronal holes. Since the speed, duration and southward magnetic field component determine the severity of space weather effects, the geospace environment responds quite differently to these two coronal hole distributions. Despite the fact that the present solar minimum is exceptionally quiet with sunspot numbers the lowest in 75 years, solar wind density and IMF strength at the lowest values ever observed and with geomagnetic indices and solar EUV fluxes the lowest in three solar cycles, magnetic activity at Earth is showing new features and has remained surprisingly strong. The details of newly discovered geospace and upper atmospheric effects are described and possible reasons behind them discussed. What these new data sets demonstrate is that the distribution of low-latitude open magnetic flux on the Sun is a key factor in determining how the Earth will respond to a given solar minimum. If the low sunspot conditions of solar minima have analogies to conditions during solar "grand minima" (where sunspots all but disappear for extended periods), then these new results imply that high-speed solar wind streams may introduce complexities to the Earth's response during these times as well.

  19. Solar Radius at Sub-Terahertz Frequencies

    NASA Astrophysics Data System (ADS)

    Menezes, Fabian; Valio, Adriana

    2017-10-01

    The visible surface of the Sun, or photosphere, is defined as the solar radius in the optical spectrum range located at 696,000 km (Cox et al. (Ed. 2015)). However, as the altitude increases, the dominant electromagnetic radiation is emitted at other frequencies. Our aim is to measure the solar radius at frequencies of 212 GHz and 405 GHz through out a solar cycle and, therefore, the altitude where these emissions are generated and that variation along the years. Also we tried to verify the the radius dependence on the solar activity cycle, which can be a good indicator of the changes that occur in the atmosphere structure. For this, we used data obtained by the Submillimetric Solar Telescope (SST) created from daily scans made by SST from 1990 to 2015. From these scans a 2D map of the solar disk was constructed. The solar radius is then determined by adjusting a circumference to the points where the brightness is half of the quiet Sun level, which is set as the most common temperature value in the solar map, i.e., the mode of the temperature distribution. Thus, we determined the solar radius at 212 and 405 GHz and the altitude of the emissions respectively. For 212 GHz, we obtained a radius of 976.5''+/-8'' (707+/-4 Mm), whereas for 405 GHz, we obtained 975.0''+/-8'' (707+/-5 Mm). optical spectrum range

  20. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1995-01-01

    Low-disturbance or 'quiet' wind tunnels are now considered an essential part of meaningful boundary layer transition research. Advances in Supersonic Laminar Flow Control (SLFC) technology for swept wings depends on a better understanding of the receptivity of the transition phenomena to attachment-line contamination and cross-flows. This need has provided the impetus for building the Laminar Flow Supersonic Wind Tunnel (LFSWT) at NASA-Ames, as part of the NASA High Speed Research Program (HSRP). The LFSWT was designed to provide NASA with an unequaled capability for transition research at low supersonic Mach numbers (<2.5). The following are the objectives in support of the new Fluid Mechanic Laboratory (FML) quiet supersonic wind tunnel: (I) Develop a unique injector drive system using the existing FML indraft compressor; (2) Develop an FML instrumentation capability for quiet supersonic wind tunnel evaluation and transition studies at NASA-Ames; (3) Determine the State of the Art in quiet supersonic wind tunnel design; (4) Build and commission the LFSWT; (5) Make detailed flow quality measurements in the LFSWT; (6) Perform tests of swept wing models in the LFSWT in support of the NASA HSR program; and (7) Provide documentation of research progress.

  1. Confronting the Quiet Crisis: How Chief State School Officers Are Advancing Quality Early Childhood Opportunities

    ERIC Educational Resources Information Center

    Council of Chief State School Officers, 2012

    2012-01-01

    In 2009, the Council of Chief State School Officers (CCSSO) adopted a new policy statement on early childhood education. Based on the work of a task force of 13 chiefs, "A Quiet Crisis: The Urgent Need to Build Early Childhood Systems and Quality Programs for Children Birth to Age Five" presents a compelling argument for why public…

  2. Quiet Clean Short-Haul Experimental Engine (QSCEE). Preliminary analyses and design report, volume 1

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The experimental propulsion systems to be built and tested in the 'quiet, clean, short-haul experimental engine' program are presented. The flight propulsion systems are also presented. The following areas are discussed: acoustic design; emissions control; engine cycle and performance; fan aerodynamic design; variable-pitch actuation systems; fan rotor mechanical design; fan frame mechanical design; and reduction gear design.

  3. The Epistemology of Mathematical and Statistical Modeling: A Quiet Methodological Revolution

    ERIC Educational Resources Information Center

    Rodgers, Joseph Lee

    2010-01-01

    A quiet methodological revolution, a modeling revolution, has occurred over the past several decades, almost without discussion. In contrast, the 20th century ended with contentious argument over the utility of null hypothesis significance testing (NHST). The NHST controversy may have been at least partially irrelevant, because in certain ways the…

  4. White dwarf models for type 1 supernovae and quiet supernovae, and presupernova evolution

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1980-01-01

    Supernova mechanisms in accreting white dwarfs are considered with emphasis on deflagration as a plausible mechanism for producing Type I supernovae and electron captures to form quiet supernovae leaving neutron stars. These outcomes depend on accretion rate of helium, initial mass and composition of the white dwarf. The various types of hydrogen shell burning in the presupernova stage are also discussed.

  5. Organization of Functional Postural Responses Following Perturbations in Multiple Directions in Elderly Fallers Standing Quietly

    ERIC Educational Resources Information Center

    Matjacic, Zlatko; Sok, David; Jakovljevic, Miroljub; Cikajlo, Imre

    2013-01-01

    The objective of the study was to assess functional postural responses by analyzing the center-of-pressure trajectories resulting from perturbations delivered in multiple directions to elderly fallers. Ten elderly individuals were standing quietly on two force platforms while an apparatus delivered controlled perturbations at the level of pelvis…

  6. Kiddie QR (Quieting Reflex): Field Testing a Relaxation Program for Young Children.

    ERIC Educational Resources Information Center

    Ragan, Lynne; Hiebert, Bryan

    1987-01-01

    Investigated the efficacy of implementing "Kiddie QR (Quieting Reflex)," a self-regulation procedure with primary grade students in a classroom setting. Results were not strongly supportive. Low pretest scores of anxiety and lack of adherence to the program by teachers have influenced the outcome. (ABB)

  7. Participant Characteristics and the Effects of Two Types of Meditation versus Quiet Sitting.

    ERIC Educational Resources Information Center

    Fling, Sheila; And Others

    1981-01-01

    Compared restricted and expanded awareness types of meditation with quiet sitting, and controls. All groups except controls became less anxious, more intuitive, and more internal on locus of control. Found little evidence of differential change across groups. Those practicing more showed more anxiety reduction. (JAC)

  8. Brief quiet ego contemplation reduces oxidative stress and mind-wandering

    PubMed Central

    Wayment, Heidi A.; Collier, Ann F.; Birkett, Melissa; Traustadóttir, Tinna; Till, Robert E.

    2015-01-01

    Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student’s compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives. PMID:26483734

  9. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... within a single political jurisdiction shall be separated by at least one public highway-rail grade... include grade crossings on a segment of rail line crossing more than one political jurisdiction. (b... be credited in calculating the Quiet Zone Risk Index. (c) Advance warning signs. (1) Each highway...

  10. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... within a single political jurisdiction shall be separated by at least one public highway-rail grade... include grade crossings on a segment of rail line crossing more than one political jurisdiction. (b... be credited in calculating the Quiet Zone Risk Index. (c) Advance warning signs. (1) Each highway...

  11. The Quiet Room: A Cyber-Free Haven in the Community Library.

    ERIC Educational Resources Information Center

    Jacob, Bernard; Morphew, Carol

    1997-01-01

    Because community libraries are becoming centers of suburban and "exurban" activity, quiet study rooms are being constructed for customers intent on concentrated study. Discusses functional (size, location, furniture) and physical (acoustic, heating, ventilation, air conditioning, lighting, electronic support) considerations of quiet…

  12. Effects of road traffic noise and the benefit of access to quietness

    NASA Astrophysics Data System (ADS)

    Öhrström, E.; Skånberg, A.; Svensson, H.; Gidlöf-Gunnarsson, A.

    2006-08-01

    Socio-acoustic surveys were carried out as part of the Soundscape Support to Health research programme to assess the health effects of various soundscapes in residential areas. The study was designed to test whether having access to a quiet side of one's dwelling enhances opportunities for relaxation and reduces noise annoyance and other adverse health effects related to noise. The dwellings chosen were exposed to sound levels from road traffic ranging from about L=45-68 dB at the most-exposed side. The study involved 956 individuals aged 18-75 years. The results demonstrate that access to quiet indoor and outdoor sections of one's dwelling supports health; it produces a lower degree and extent of annoyance and disturbed daytime relaxation, improves sleep and contributes to physiological and psychological well-being. Having access to a quiet side of one's dwelling reduces disturbances by an average of 30-50% for the various critical effects, and corresponds to a reduction in sound levels of ( LAeq,24h) 5 dB at the most-exposed side. To protect most people (80%) from annoyance and other adverse effects, sound levels from road traffic should not exceed ( LAeq,24h) 60 dB at the most-exposed side, even if there is access to a quiet side of one's dwelling ( LAeq,24h⩽45 dB).

  13. Behavioral effect of knee joint motion on body's center of mass during human quiet standing.

    PubMed

    Yamamoto, Akio; Sasagawa, Shun; Oba, Naoko; Nakazawa, Kimitaka

    2015-01-01

    The balance control mechanism during upright standing has often been investigated using single- or double-link inverted pendulum models, involving the ankle joint only or both the ankle and hip joints, respectively. Several studies, however, have reported that knee joint motion during quiet standing cannot be ignored. This study aimed to investigate the degree to which knee joint motion contributes to the center of mass (COM) kinematics during quiet standing. Eight healthy adults were asked to stand quietly for 30s on a force platform. Angular displacements and accelerations of the ankle, knee, and hip joints were calculated from kinematic data obtained by a motion capture system. We found that the amplitude of the angular acceleration was smallest in the ankle joint and largest in the hip joint (ankle < knee < hip). These angular accelerations were then substituted into three biomechanical models with or without the knee joint to estimate COM acceleration in the anterior-posterior direction. Although the "without-knee" models greatly overestimated the COM acceleration, the COM acceleration estimated by the "with-knee" model was similar to the actual acceleration obtained from force platform measurement. These results indicate substantial effects of knee joint motion on the COM kinematics during quiet standing. We suggest that investigations based on the multi-joint model, including the knee joint, are required to reveal the physiologically plausible balance control mechanism implemented by the central nervous system. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Sounds of shallow water fishes pitch within the quiet window of the habitat ambient noise.

    PubMed

    Lugli, Marco

    2010-06-01

    The habitat ambient noise may exert an important selective pressure on frequencies used in acoustic communication by animals. A previous study demonstrated the presence of a match between the low-frequency quiet region of the stream ambient noise (termed 'quiet window') and the main frequencies used for sound production and hearing by two stream gobies (Padogobius bonelli, Gobius nigricans). The present study examines the spectral features of ambient noise in very shallow freshwater, brackish and marine habitats and correlates them to the range of dominant frequencies of sounds used by nine species of Mediterranean gobies reproducing in these environments. Ambient noise spectra of these habitats featured a low-frequency quiet window centered at 100 Hz (stream, sandy/rocky sea shore), or at 200 Hz (spring, brackish lagoon). The analysis of the ambient noise/sound spectrum relationships showed the sound frequencies matched the frequency band of the quiet window in the ambient noise typical of their own habitat. Analogous ambient noise/sound frequency relationships were observed in other shallow-water teleosts living in similar underwater environments. Conclusions may be relevant to the understanding of evolution of fish acoustic communication and hearing.

  15. Effect of Minimal Hearing Loss on Children's Ability to Multitask in Quiet and in Noise

    ERIC Educational Resources Information Center

    McFadden, Brittany; Pittman, Andrea

    2008-01-01

    Purpose: The purpose of the present study was to examine the effect of minimal hearing loss (HL) on children's ability to perform simultaneous tasks in quiet and in noise. Method: Ten children with minimal HL and 11 children with normal hearing (NH) participated. Both groups ranged in age from 8 to 12 years. The children categorized common words…

  16. The Quiet Room: A Cyber-Free Haven in the Community Library.

    ERIC Educational Resources Information Center

    Jacob, Bernard; Morphew, Carol

    1997-01-01

    Because community libraries are becoming centers of suburban and "exurban" activity, quiet study rooms are being constructed for customers intent on concentrated study. Discusses functional (size, location, furniture) and physical (acoustic, heating, ventilation, air conditioning, lighting, electronic support) considerations of quiet…

  17. Organization of Functional Postural Responses Following Perturbations in Multiple Directions in Elderly Fallers Standing Quietly

    ERIC Educational Resources Information Center

    Matjacic, Zlatko; Sok, David; Jakovljevic, Miroljub; Cikajlo, Imre

    2013-01-01

    The objective of the study was to assess functional postural responses by analyzing the center-of-pressure trajectories resulting from perturbations delivered in multiple directions to elderly fallers. Ten elderly individuals were standing quietly on two force platforms while an apparatus delivered controlled perturbations at the level of pelvis…

  18. Children's perception of nonnative-accented sentences in noise and quiet.

    PubMed

    Bent, Tessa; Atagi, Eriko

    2015-12-01

    Adult listeners' word recognition is remarkably robust under a variety of adverse listening conditions. However, the combination of two simultaneous listening challenges (e.g., nonnative speaker in noise) can cause significant word recognition decrements. This study investigated how talker-related (native vs nonnative) and environment-related (noise vs quiet) adverse conditions impact children's and adults' word recognition. Five- and six-year-old children and adults identified sentences produced by one native and one nonnative talker in both quiet and noise-added conditions. Children's word recognition declined significantly more than adults' in conditions with one source of listening adversity (i.e., native speaker in noise or nonnative speaker in quiet). Children's performance when the listening challenges were combined (nonnative talker in noise) was particularly poor. Immature speech-in-noise perception may be a result of children's difficulties with signal segregation or selective attention. In contrast, the explanation for children's difficulty in the mapping of unfamiliar pronunciations to known words in quiet listening conditions must rest on children's limited cognitive or linguistic skills and experiences. These results demonstrate that children's word recognition abilities under both environmental- and talker-related adversity are still developing in the early school-age years.

  19. Aborted jets and the X-ray emission of radio-quiet AGNs

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Haardt, F.; Matt, G.

    2004-01-01

    We propose that radio-quiet quasars and Seyfert galaxies have central black holes powering outflows and jets which propagate only for a short distance, because the velocity of the ejected material is smaller than the escape velocity. We call them ``aborted" jets. If the central engine works intermittently, blobs of material may be produced, which can reach a maximum radial distance and then fall back, colliding with the blobs produced later and still moving outwards. These collisions dissipate the bulk kinetic energy of the blobs by heating the plasma, and can be responsible (entirely or at least in part) for the generation of the high energy emission in radio-quiet objects. This is alternative to the more conventional scenario in which the X-ray spectrum of radio-quiet sources originates in a hot (and possibly patchy) corona above the accretion disk. In the latter case the ultimate source of energy of the emission of both the disk and the corona is accretion. Here we instead propose that the high energy emission is powered also by the extraction of the rotational energy of the black hole (and possibly of the disk). By means of Montecarlo simulations we calculate the time dependent spectra and light curves, and discuss their relevance to the X-ray spectra in radio-quiet AGNs and galactic black hole sources. In particular, we show that time variability and spectra are similar to those observed in Narrow Line Seyfert 1 galaxies.

  20. Of Chickens, Eggs, and Expertise: Observations Complimentary and Contrary to "The Quiet Evolution."

    ERIC Educational Resources Information Center

    Lankford, E. Louis

    1999-01-01

    Responds to Brent Wilson's report "The Quiet Evolution: Changing the Face of Arts Education," focusing on how Wilson centers the curriculum around key works of art. Explains that ideas, issues, and themes should be central instead and addresses the development of teacher expertise. (CMK)