Journal articles: 'Solar flux density'

1

Kovalenko, V. A. "Manifestation of solar activity in solar wind particle flux density." Planetary and Space Science 36, no. 12 (December 1988): 1343–58. http://dx.doi.org/10.1016/0032-0633(88)90004-9.

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2

Andreychuk, Vladimir, and Yaroslav Filyuk. "ANALYSIS OF THE ENERGY POTENTIAL OF SOLAR LIGHT OF THE WESTERN REGION OF UKRAINE WITH THE ACCOUNT OF CLIMATIC CONDITIONS." EUREKA: Physics and Engineering 4 (July 31, 2017): 25–32. http://dx.doi.org/10.21303/2461-4262.2017.00398.

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An experimental facility for measuring and recording the flux density of solar radiation is designed and installed. An electrical circuit is developed and a pyranometer model is developed to measure the level of solar radiation, and it is graduated with a Soler Power Meter DT-1307 solar radiation flux meter. The time distribution of the flux density of solar energy is analyzed and the surface energy density of solar radiation is calculated for Ternopil. The influence of climatic conditions on the energy of solar radiation is determined. Analytical dependencies are obtained on the basis of comparison of the measured values of the flux density of solar radiation and the cloud cover taken from meteorological services. The energy potential of solar radiation during 2012-2015 in the western region of Ukraine is calculated, as well as the average monthly and average annual energy density of solar radiation. It is determined that the annual average density of the solar energy flux is 1045.9 kW∙h/m2, and its deviation does not exceed 5%. It is shown that the most favorable months for the use of solar energy are from March to September of each year.

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3

Ulmer, Steffen, Eckhard Lüpfert, Markus Pfänder, and Reiner Buck. "Calibration corrections of solar tower flux density measurements." Energy 29, no. 5-6 (April 2004): 925–33. http://dx.doi.org/10.1016/s0360-5442(03)00197-x.

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4

Liao, Zhirong, Xin Li, Chao Xu, Chun Chang, and Zhifeng Wang. "Allowable flux density on a solar central receiver." Renewable Energy 62 (February 2014): 747–53. http://dx.doi.org/10.1016/j.renene.2013.08.044.

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5

Сетов, Артём, Artem Setov, Мария Глоба, Mariia Globa, Андрей Медведев, Andrey Medvedev, Роман Васильев, Roman Vasilyev, Дмитрий Кушнарев, and Dmitriy Kushnarev. "First results of absolute measurements of solar flux at the Irkutsk Incoherent Scatter Radar (IISR)." Solar-Terrestrial Physics 4, no. 3 (September 28, 2018): 24–27. http://dx.doi.org/10.12737/stp-43201804.

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The Irkutsk Incoherent Scatter Radar (IISR) allows us to carry out passive radio observations of the Sun and other powerful radio sources. We describe a method for absolute measurements of spectral flux density of solar radiation at IISR. The absolute measurements are meant to determine the flux density in physical units [W·m–2·Hz–1]. The IISR antenna is a horn with frequency beam steering, therefore radio sources can be observed at different frequencies. Also there is a polarization filter in the antenna aperture, which passes only single (horizontal) polarization. To acquire flux density absolute values, the IISR receiver is calibrated by the Cygnus-A radiation. Since the Sun’s position in the IISR antenna pattern is determined by a frequency differing from the Cygnus-A observation frequency, we perform an additional calibration of the frequency response in the 154–162 MHz operation frequency range, using the background sky noise. The solar disk size is comparable with the main beam width in the north—south direction, hence the need to take into account the shape of the brightness distribution in the operation frequency range. The average flux density of the quiet-Sun radiation was ~5 sfu (solar flux units, 10–22 W·m–2·Hz–1) at the 161 MHz frequency.

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6

van Driel-Gesztelyi, L., P. Démoulin, J. Ireland, B. Thompson, A. Fludra, K. Oláh, Zs Kővári, et al. "An Observational Test for Solar Atmospheric Heating." Symposium - International Astronomical Union 203 (2001): 514–16. http://dx.doi.org/10.1017/s0074180900219906.

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We study the evolution of the emissivity correlated with magnetic flux density of an active region from its birth until its decay throughout all atmospheric layers. We analyse multi-wavelength data obtained from SOHO, Yohkoh, GOES, SOLSTICE and 10.7 cm radio data from DRAO, Canada. We utilise our results to understand the scaling laws in different atmospheric layers. We confirm that the relationship between the emitted excess flux (flux - basal flux) and photospheric magnetic flux density ΔF(< f B >) follow power laws, and the powers depend on the formation temperature of the line(s) involved.

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7

Cameron, R. H., and J. Jiang. "The relationship between flux emergence and subsurface toroidal magnetic flux." Astronomy & Astrophysics 631 (October 15, 2019): A27. http://dx.doi.org/10.1051/0004-6361/201834852.

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Aims. The 1D mean-field equation describing the evolution of the subsurface toroidal field can be used with the observed surface radial field to model the subsurface toroidal flux density. Our aim is to test this model and determine the relationship between the observationally inferred surface toroidal field (as a proxy for flux emergence), and the modelled subsurface toroidal flux density. Methods. We used a combination of sunspot area observations and the surface toroidal field inferred from Wilcox Solar Observatory (WSO) line-of-sight magnetic field observations. We then compared them with the results of a 1D mean-field evolution equation for the subsurface toroidal field, driven by the observed radial field from the National Solar Observatory/Kitt Peak and SOLIS observations. Results. We derive calibration curves relating the subsurface toroidal flux density to the observed surface toroidal field strengths and sunspot areas. The calibration curves are for two regimes, one corresponding to ephemeral region emergence outside of the butterfly wings, the other to active region emergence in the butterfly wings. We discuss this in terms of the size and vertical velocity associated with the two types of flux emergence.

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8

Steiner, O. "Distribution of magnetic flux density at the solar surface." Astronomy & Astrophysics 406, no. 3 (August 2003): 1083–88. http://dx.doi.org/10.1051/0004-6361:20030753.

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9

Schiemenz, Fabian, Jens Utzmann, and Hakan Kayal. "Propagating EUV solar flux uncertainty to atmospheric density uncertainty." Advances in Space Research 63, no. 12 (June 2019): 3936–52. http://dx.doi.org/10.1016/j.asr.2019.02.040.

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10

Schubnell, M., J. Keller, and A. Imhof. "Flux Density Distribution in the Focal Region of a Solar Concentrator System." Journal of Solar Energy Engineering 113, no. 2 (May 1, 1991): 112–16. http://dx.doi.org/10.1115/1.2929954.

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In high temperature solar energy applications highly concentrating optical systems, such as, e.g., parabolic dishes, achieve typical radiation flux densities >2 MW/m2. In order to investigate thermo and photochemical reactions at temperatures >1500 K and radiation flux densities >2 MW/m2 a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is a prefocusing glass heliostat with a focal length of 100 m. The second stage is a highly concentrating parabolic dish with a focal length of 1.93 m. To design experiments to be carried out in the focal region of the parabolic dish, the radiation flux as well as its density distribution have to be known. This distribution is usually measured by radiometric methods. However, these methods are generally rather troublesome because of the high temperatures involved. In this paper we present a simple method to estimate the characteristic features of the radiation flux density distribution in the focal region of a concentrator system. It is well known from solar eclipses that the mean angular diameter of the moon is almost equal to that of the sun (9.1 mrad versus 9.3 mrad). Hence, the lunar disk is well suited to be used as a light source to investigate the flux distribution in a solar furnace. Compared to the sun the flux density is reduced by 4·105 and the flux density distribution can be inspected on a sheet of paper located in the plane of interest, e.g., the focal plane. This distribution was photographed and analyzed by means of an image processing system. The density distribution was also simulated using a Monte Carlo ray tracing program. Based on this comparison, and on further ray tracing computations, we show that the peak flux density decreases from 8.9 MW/m2 in December to values below 4 MW/m2 in June and the net radiation flux from 25 kW to 15 kW, respectively.

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11

Oudrane, A., B. Aour, B. Zeghmati, X. Chesneau, and H. Massaoud. "Study and Simulation of the Density of the Incident Solar Flux on the Walls of a Building in Adrar, Algeria." Engineering, Technology & Applied Science Research 7, no. 5 (October 19, 2017): 1940–45. http://dx.doi.org/10.48084/etasr.1337.

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In this work, we studied the effect of external climatic conditions on the evolution of the daily solar flux incident on the walls of a building located at Adrar region in the South of Algeria. This building is designed for heating or air conditioning applications. Numerical simulations allowed to compare the variation of the incident solar flux over a full day on the south, east, north and west walls of the building to the values of the solar flux on a horizontal wall (the outer ceiling). The horizontal global solar flux is calculated using a Gaussian sinusoidal function. The simulations were carried out in the case of a building located in a desert zone. The results of the numerical simulation showed the effect of the orientation of the building on the evolution of the incident daily solar flux.

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12

Poudel, P., N. Parajuli, A. Gautam, D. Sapkota, H. Adhikari, B. Adhikari, A. Silwal, S. P. Gautam, M. Karki, and R. K. Mishra. "Wavelet and Cross-Correlation Analysis of Relativistic Electron Flux with Sunspot Number, Solar Flux, and Solar Wind Parameters." Journal of Nepal Physical Society 6, no. 2 (December 31, 2020): 104–12. http://dx.doi.org/10.3126/jnphyssoc.v6i2.34865.

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The Geostationary Operational Environmental Satellites (GOES) have been monitoring the Earth's radiation environment and is providing the electron flux data (of energy >0.8 MeV, >2 MeV, and >4 MeV) by means of a connected sensor subsystem. Relativistic electron flux is one of the components of the radiation belt which not only affects the electrical system in satellites but also has an impact on Earth’s upper atmospheric climatic variation. We have carried out a study to determine the relation of sunspot number (R), solar flux (F10.7), and solar wind parameters i.e., solar wind velocity (Vsw), plasma density Nsw), the southern component of the interplanetary magnetic field (IMF-Bz), Plasma temperature (Tsw) with relativistic electron flux of energy >0.8 MeV, >2 MeV, and >4 MeV in outer radiation belt using the data of 24 years (1996-2020) covering solar cycle 23 and 24. Time series analysis, Cross-correlation and wavelet analysis techniques have been used in this study. The time series plot displayed that the radiation is occupied mostly by electron flux of energy less than 4 Mev and solar cycle 23 (1996-2008) was strong to produce more intensity of relativistic electron flux of all energy in comparison to cycle 24 (2008-2019). Results from cross-correlation analysis illustrated that Bz has no significant impact on the enhancement of relativistic electron flux of any energy range in the radiation belt. Whereas other studied parameters have a positive correlation with relativistic electron flux, but with significantly different coefficient values for different energy. We found that electron flux >0.8 MeV and >2 MeV has a strong positive association with sunspot number, solar flux, solar wind velocity, plasma density and temperature whereas weak correlation with electron flux of energy >4 MeV. This result leads us to conclude that solar activity and solar parameters have greater influence in producing relativistic electron flux of energy ~ 0.8-4 MeV, than of flux > 4 MeV. The study made to observe the distribution of relativistic electrons in radiation belt with time through continuous wavelet analysis showed that electron flux of energy >0.8 has a higher periodicity in comparison to the flux of other energy ranger.

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13

Parretta, A., A. Antonini, M. Armani, G. Nenna, G. Flaminio, and M. Pellegrino. "Double-cavity radiometer for high-flux density solar radiation measurements." Applied Optics 46, no. 12 (April 3, 2007): 2166. http://dx.doi.org/10.1364/ao.46.002166.

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14

Erdős, G., and A. Balogh. "MAGNETIC FLUX DENSITY IN THE HELIOSPHERE THROUGH SEVERAL SOLAR CYCLES." Astrophysical Journal 781, no. 1 (January 7, 2014): 50. http://dx.doi.org/10.1088/0004-637x/781/1/50.

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15

WEI Su, 魏. 素., 肖. 君. XIAO Jun, 魏秀东 WEI Xiu-dong, 卢振武 LU Zhen-wu, and 王. 肖. WANG Xiao. "Evaluation of flux density measurement method for concentrated solar irradiance." Chinese Optics 9, no. 2 (2016): 255–62. http://dx.doi.org/10.3788/co.20160902.0255.

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16

Zhou Shu-rong, Xu Fu-ying, and Yu Xing-feng. "Absolute calibration of solar radio flux density at 9375 MHz." Chinese Astronomy and Astrophysics 16, no. 1 (January 1992): 112. http://dx.doi.org/10.1016/0275-1062(92)90024-6.

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17

Vasiluta, Petre, Ileana Ioana Cofaru, Nicolae Florin Cofaru, and Dragos Laurentiu Popa. "Studies of the Solar Radiations' Influence About Geomembranes Used in Ecological Landfill." ACTA Universitatis Cibiniensis 69, no. 1 (December 20, 2017): 148–54. http://dx.doi.org/10.1515/aucts-2017-0019.

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Abstract The study shown in this paper presents the behavior of geomembranes used at the ecological landfills. The influences of the solar radiations has a great importance regarding the correct mounting of the geomembranes. The mathematical model developed for the determination anytime and anywhere in the world for the next values and parameters: apparent solar time, solar declination, solar altitude, solar azimuth and incidence angle, zone angle, angle of sun elevation, solar declination, solar constant, solar flux density, diffuse solar radiation, global radiation, soil albedo, total radiant flux density and relational links of these values. The results of this model was used for creations an AutoCAD subroutines useful for choosing the correct time for correct mounting anywhere of the geomembranes

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18

Fu, Shuai, Yong Jiang, and Xiaoping Zhang. "Effects of Solar Activity on Ionospheric Ion Upflow During Geomagnetic Quiet Periods: DMSP Observations." Open Astronomy 29, no. 1 (October 15, 2020): 158–67. http://dx.doi.org/10.1515/astro-2020-0018.

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AbstractBased on the Defense Meteorological Satellite Program (DMSP) observations during Solar Cycle 23, this paper examines solar activity dependence of ionospheric bulk ion upflow events (IUEs) in the Southern Hemisphere (SH). Much previous similar work was conducted over the Northern Hemisphere (NH) with measurements from European Incoherent Scatter (EISCAT). To eliminate the influence of geomagnetic disturbance on IUEs, we pick out observations during geomagnetic quiet periods (with Kp ≤ 2+). Results show that, ion upward densities and fluxes are dramatically elevated at times of high solar activity (HSA) but ion upward drifts and occurrences are increased at times of low solar activity (LSA) in the SH, which is consistent with the situation in the NH. The ratios between HSA and LSA for these four parameters (IUEs’ density, flux, upward drift and occurrence) are ~2.71, ~1.98, ~0.76 and ~0.57, respectively. Furthermore, lower flux event takes place frequently at LSA as the background ion density is low but the upward drift is large, while higher flux event happens commonly at times of HSA accompanied by high ion density but low upward velocity. Quantitatively, an increase in unit of solar activity (characterized by P index) causes a 4.2×108 m−3 increase in ion density and a 1.2×1011 m−2·s−1 enhancement in upward flux, together with a 0.6 m·s−1 and 0.02 % decrease in ion upward velocity and uprate, respectively. The acceleration from the ambipolar electric field is thought to be a possible mechanism affecting the dependence of IUEs on solar variations. For HSA, the acceleration from the ambipolar electric field weakens, but a large number of background ions provide abundant seeds for acceleration and upflow, which maintains a high IUE flux. It is inferred that upflow events and upward drifts are inhibited by the enhanced ionospheric background density.

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19

Ferriere, A., G. P. Rodriguez, and J. A. Sobrino. "Flux Distribution Delivered by a Fresnel Lens Used for Concentrating Solar Energy." Journal of Solar Energy Engineering 126, no. 1 (February 1, 2004): 654–60. http://dx.doi.org/10.1115/1.1638783.

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The flux distribution delivered by a Fresnel lens when concentrating solar energy is characterized. The flux is measured with a Si photo-detector equipped with an integrating sphere. Flux mapping is performed by scanning lines at discrete positions on one plane. The peak concentration is determined as well as the distribution of the flux density in 3-D inside the focal area. Future utilization of this Fresnel lens for solar processing and surface modifications of materials is discussed. The analysis is made on the basis of the optical characteristics of the device and of the results of previous works in the same field. The size of the focus and the peak flux density are key parameters for examining the candidate processing and for discussing the dimensions of the treated components.

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20

Сетов, Артём, Artem Setov, Мария Глоба, Mariia Globa, Андрей Медведев, Andrey Medvedev, Роман Васильев, Roman Vasilyev, Дмитрий Кушнарев, and Dmitriy Kushnarev. "First results of absolute measurements of solar flux at the Irkutsk Incoherent Scatter Radar (IISR)." Solnechno-Zemnaya Fizika 4, no. 3 (September 28, 2018): 33–38. http://dx.doi.org/10.12737/szf-43201804.

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The Irkutsk Incoherent Scatter Radar (IISR) allows us to carry out passive radio observations of the Sun and other powerful radio sources. We describe a method for absolute measurements of spectral flux density of solar radiation at IISR. Absolute measurements are meant to determine the flux density in physical units [W·m–2·Hz–1]. The IISR antenna is a horn with frequency beam steering, therefore radio sources can be observed at different frequencies. Also there is a polarization filter in the antenna aperture, which passes only single (horizontal) polarization. To acquire flux density absolute values, the IISR receiver is calibrated by the Cygnus-A radiation. Since the Sun’s position in the IISR antenna pattern is determined by a frequency differing from the Cygnus-A observation frequency, we perform an additional calibration of the antenna overall frequency response in the 154–162 MHz operation frequency range, using the background sky noise. The solar disk size is comparable with the main beam width in the north—south direction, hence the need to take into account the shape of the brightness distribution in the operation frequency range. The average flux density of the quiet-Sun radiation was ~5 sfu (solar flux units, 10–22 W·m–2·Hz–1) at the 161 MHz frequency.

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21

Bigazzi, Alberto, Carlo Cauli, and Francesco Berrilli. "Lower-thermosphere response to solar activity: an empirical-mode-decomposition analysis of GOCE 2009–2012 data." Annales Geophysicae 38, no. 3 (June 30, 2020): 789–800. http://dx.doi.org/10.5194/angeo-38-789-2020.

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Abstract. Forecasting the thermosphere (the atmosphere's uppermost layer, from about 90 to 800 km altitude) is crucial to space-related applications, from space mission design to re-entry operations, space surveillance and more. Thermospheric dynamics is directly linked to the solar dynamics through the solar UV (ultraviolet) input, which is highly variable, and through the solar wind and plasma fluxes impacting Earth's magnetosphere. The solar input is non-periodic and non-stationary, with long-term modulations from the solar rotation and the solar cycle and impulsive components, due to magnetic storms. Proxies of the solar input exist and may be used to forecast the thermosphere, such as the F10.7 radio flux and the Mg II EUV (extreme-ultraviolet) flux. They relate to physical processes of the solar atmosphere. Other indices, such as the Ap geomagnetic index, connect with Earth's geomagnetic environment. We analyse the proxies' time series comparing them with in situ density data from the ESA (European Space Agency) GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) gravity mission, operational from March 2009 to November 2013, therefore covering the full rising phase of solar cycle 24, exposing the entire dynamic range of the solar input. We use empirical mode decomposition (EMD), an analysis technique appropriate to non-periodic, multi-scale signals. Data are taken at an altitude of 260 km, exceptionally low for a low-Earth-orbit (LEO) satellite, where density variations are the single most important perturbation to satellite dynamics. We show that the synthesized signal from optimally selected combinations of proxy basis functions, notably Mg II for the solar flux and Ap for the plasma component, shows a very good agreement with thermospheric data obtained by GOCE, during periods of low and medium solar activity. In periods of maximum solar activity, density enhancements are also well represented. The Mg II index proves to be, in general, a better proxy than the F10.7 index for modelling the solar flux because of its specific response to the UV spectrum, whose variations have the largest impact over thermospheric density.

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22

Faurobert, M., and G. Ricort. "Magnetic flux structuring of the quiet Sun internetwork." Astronomy & Astrophysics 651 (July 2021): A21. http://dx.doi.org/10.1051/0004-6361/202140705.

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Context. The small-scale magnetism of the quiet Sun has been investigated by various means in recent decades. It is now well established that the quiet Sun contains in total more magnetic flux than active regions and represents an important reservoir of magnetic energy. But the nature and evolution of these fields remain largely unknown. Aims. We investigate the solar-cycle and center-to-limb variations of magnetic-flux structures at small scales in internetwork regions of the quiet Sun. Methods. We used Hinode SOT/SP data from the irradiance program between 2008 and 2016. Maps of the magnetic-flux density are derived from the center-of gravity method applied to the circular polarization profiles in the FeI 630.15 nm and FeI 630.25 nm lines. To correct the maps from the instrumental smearing of the telescope, we applied a deconvolution method based on a principal component analysis of the line profiles and on a Richardson-Lucy deconvolution of their coefficients. We took defocus effects and the diffraction of the SOT telescope into account. We then performed a spectral analysis of the spatial fluctuations of the magnetic-flux density in 10″ × 10″ internetwork regions spanning a wide range of latitudes from ±70° to the equator. Results. At low and mid latitudes the power spectra normalized by the mean value of the unsigned flux in the regions do not vary significantly with the solar cycle. However at solar maximum for one scan in the activity belt showing an enhanced network, a marginal increase in the power of the magnetic fluctuations is observed at granular and larger scales in the internetwork. At high latitudes, we observe variations at granular and larger scales where the power decreases at solar maximum. At all the latitudes the power of the magnetic fluctuations at scales smaller than 0.5″ remains constant throughout the solar cycle. Conclusions. At the equator the unsigned flux density is related to the vertical component of the magnetic field, whereas at high latitudes this flux density is mainly related to the horizontal component and probe higher altitudes. Our results favor a small-scale dynamo that operates in the internetwork, but they show that the global dynamo also contributes to the internetwork fields. At solar maximum the high-latitude horizontal internetwork fields seem to be depleted from the structures at granular and larger scales that are seen at solar minimum, whereas the internetwork within enhanced network regions show more structures at those scales than at solar minimum.

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23

Hansteen, V. H. "Solar Wind Acceleration." International Astronomical Union Colloquium 144 (1994): 453–60. http://dx.doi.org/10.1017/s0252921100025781.

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AbstractThe general aspects of solar wind acceleration are well described by considering the thermally driven outflow from an electron – proton corona. However, two puzzling observations remain to be explained: 1) The predicted asymptotic flow velocity is much lower than that observed in high speed streams, and 2) The proton flux observed at 1AU varies considerably less than expected when considering the sensitivity of the proton flux to the coronal temperature predicted by thermally driven models. The solution of the first problem rests upon finding a mechanism which can deposit energy and/or momentum beyond the critical point of the flow. The invariance of the proton flux requires that a mechanism for maintaining a relatively constant proton density scale height in the subsonic region of the flow is found. One such possibility lies in considering the effects of an enhanced coronal helium abundance on the force balance of the subsonic flow. This scenario is discussed in some depth.

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Shen, Fei, and Weidong Huang. "Study on the Optical Properties of the Point-Focus Fresnel System." Sustainability 13, no. 18 (September 16, 2021): 10367. http://dx.doi.org/10.3390/su131810367.

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The characteristic analysis of the flux formed by the heliostat in the optical system is the basis in design and optimization of the whole system. In this paper, our research subject is a pilot installation of the point-focus Fresnel system, which is a new optical design between the tower system and the dish system. For the optical system, it is very important to accurately calculate the solar flux density distribution on the receiver plane. Aiming at the case that the focal length of the heliostat is not equal to the distance from the center of the heliostat to the center of the receiver plane, based on the projection, an approximate calculation method is proposed. Using the method to calculate the solar flux density distribution of the point-focus Fresnel system, and the results are compared with that calculated by SolTrace code, it is found that the solar flux density distribution of both is relatively consistent in shape and numerical value, which verifies the accuracy of the method and it can be used for design and optimization of the point-focus Fresnel system.

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25

Ikeda, Akihiro, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, and Shuji Abe. "Schumann resonance parameters at Kuju station during solar flares." E3S Web of Conferences 62 (2018): 01012. http://dx.doi.org/10.1051/e3sconf/20186201012.

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We examined the Schumann resonance (SR) at low-latitude station KUJ by comparing with solar X-ray flux and solar proton flux at a geostationary orbit. For intense solar activity in October-November 2003, the reaction of the SR frequency to X-ray enhancement and SPEs was different. The SR frequency in H component increased at the time of the Xray enhancement. The response of SR seems to be caused by the increase of the electron density in the ionospheric D region which ionized by the enhanced solar X-ray flux. In the case of the SPEs, the SR frequency in D component decreased with enhancement of solar proton flux. We suggest that the SPEs caused the decrease of altitude on the ionopheric D region at high-latitude region, and the SR frequency decreased.

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Elsayed, M., and K. A. Fathalah. "Solar Flux-Density Distribution due to Partially Shaded/Blocked Mirrors Using the Separation of Variables/Superposition Technique With Polynomial and Gaussian Sunshapes." Journal of Solar Energy Engineering 118, no. 2 (May 1, 1996): 107–14. http://dx.doi.org/10.1115/1.2847971.

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In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the flux density distribution on the receiver surfaces of solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error density functions. Also, a simplified numerical procedure is presented to determine the basic flux density function on which the technique depends. The technique is used to predict the receiver solar flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.

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27

Ma Baohong, 马保宏, 葛素红 Ge Suhong, and 李守义 Li Shouyi. "Investigation of Energy-Flux-Density Distribution of Parabolic Trough Solar Concentrators." Laser & Optoelectronics Progress 52, no. 8 (2015): 080801. http://dx.doi.org/10.3788/lop52.080801.

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28

Erdős, G., and A. Balogh. "MAGNETIC FLUX DENSITY MEASURED IN FAST AND SLOW SOLAR WIND STREAMS." Astrophysical Journal 753, no. 2 (June 21, 2012): 130. http://dx.doi.org/10.1088/0004-637x/753/2/130.

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29

Elsayed, M. M., and K. A. Fathalah. "Solar flux density distribution using a separation of variables/superposition technique." Renewable Energy 4, no. 1 (February 1994): 77–87. http://dx.doi.org/10.1016/0960-1481(94)90067-1.

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30

Dudok de Wit, Thierry, and Sean Bruinsma. "The 30 cm radio flux as a solar proxy for thermosphere density modelling." Journal of Space Weather and Space Climate 7 (2017): A9. http://dx.doi.org/10.1051/swsc/2017008.

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The 10.7 cm radio flux (F10.7) is widely used as a proxy for solar UV forcing of the upper atmosphere. However, radio emissions at other centimetric wavelengths have been routinely monitored since the 1950 s, thereby offering prospects for building proxies that may be better tailored to space weather needs. Here we advocate the 30 cm flux (F30) as a proxy that is more sensitive than F10.7 to longer wavelengths in the UV and show that it improves the response of the thermospheric density to solar forcing, as modelled with DTM (Drag Temperature Model). In particular, the model bias drops on average by 0–20% when replacing F10.7 by F30; it is also more stable (the standard deviation of the bias is 15–40% smaller) and the density variation at the the solar rotation period is reproduced with a 35–50% smaller error. We compare F30 to other solar proxies and discuss its assets and limitations.

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Vorobjev, V. G., B. V. Rezhenov, and O. I. Yagodkina. "The solar wind plasma density control of night-time auroral particle precipitation." Annales Geophysicae 22, no. 3 (March 19, 2004): 1047–52. http://dx.doi.org/10.5194/angeo-22-1047-2004.

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Abstract. DMSP F6 and F7 spacecraft observations of the average electron and ion energy, and energy fluxes in different night-time precipitation regions for the whole of 1986 were used to examine the precipitation features associated with solar wind density changes. It was found that during magnetic quietness |AL|<100nT), the enhancement of average ion fluxes was observed at least two times, along with the solar wind plasma density increase from 2 to 24cm–3. More pronounced was the ion flux enhancement that occurred in the b2i–b4s and b4s–b5 regions, which are approximately corresponding to the statistical auroral oval and map to the magnetospheric plasma sheet tailward of the isotropy boundary. The average ion energy decrease of about 2–4kev was registered simultaneously with this ion flux enhancement. The results verify the occurrence of effective penetration of the solar wind plasma into the magnetospheric tail plasma sheet. Key words. Ionosphere (auroral ionosphere, particle precipitation) – Magnetospheric physics (solar windmagnetosphere interaction)

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32

Fischer, C. E., J. M. Borrero, N. Bello González, and A. J. Kaithakkal. "Observations of solar small-scale magnetic flux-sheet emergence." Astronomy & Astrophysics 622 (February 2019): L12. http://dx.doi.org/10.1051/0004-6361/201834628.

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Aims. Two types of flux emergence were recently discovered in numerical simulations: magnetic loops and magnetic sheet emergence. While magnetic loop emergence has been documented well in recent years using high-resolution full Stokes data from ground-based telescopes as well as satellites, magnetic sheet emergence is still an understudied process. We report here on the first clear observational evidence of a magnetic sheet emergence and characterise its development. Methods. Full Stokes spectra from the Hinode spectropolarimeter were inverted with the Stokes Inversion based on Response functions (SIR) code to obtain solar atmospheric parameters such as temperature, line-of-sight velocities, and full magnetic field vector information. Results. We analyse a magnetic flux emergence event observed in the quiet-Sun internetwork. After a large-scale appearance of linear polarisation, a magnetic sheet with horizontal magnetic flux density of up to 194 Mx cm−2 hovers in the low photosphere spanning a region of 2–3 arcsec. The magnetic field azimuth obtained through Stokes inversions clearly shows an organised structure of transversal magnetic flux density emerging. The granule below the magnetic flux sheet tears the structure apart leaving the emerged flux to form several magnetic loops at the edges of the granule. Conclusions. A large amount of flux with strong horizontal magnetic fields surfaces through the interplay of buried magnetic flux and convective motions. The magnetic flux emerges within 10 minutes and we find a longitudinal magnetic flux at the foot points of the order of ∼1018 Mx. This is one to two orders of magnitude larger than what has been reported for small-scale magnetic loops. The convective flows feed the newly emerged flux into the pre-existing magnetic population on a granular scale.

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Fludra, A., and J. Ireland. "Diagnostics of Coronal Heating in Solar Active Regions." Symposium - International Astronomical Union 219 (2004): 478–82. http://dx.doi.org/10.1017/s0074180900182488.

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We study the relationship between EUV spectral line intensities and the photospheric magnetic field in solar active regions, using magnetograms from SOHO-MDI and EUV spectra of the Fe XVI 360.8 Â line (2 × 106 K) and the O V 629.7 A line (220,000 K) from the Coronal Diagnostic Spectrometer on SOHO, recorded for several active regions. We overlay and compare spatial patterns of the O V emission and the magnetic flux concentrations, with a 4″ x 4″ spatial resolution, and search for a relationship between the local O V line intensity and the photospheric magnetic flux density in each active region. While this dependence exhibits a certain amount of scatter, it can be represented by a power law fit. The average power index from all regions is 0.7 ± 0.2. Applying static loop models, we derive the dependence of the heating rate on the magnetic flux density, Eh ∝ B0.8, and compare it to the dependence predicted by the coronal heating models.

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Chen, Fei, Ming Li, and Peng Zhang. "Distribution of Energy Density and Optimization on the Surface of the Receiver for Parabolic Trough Solar Concentrator." International Journal of Photoenergy 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/120917.

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The geometrical optics model about the offset effect of solar rays by the thickness of concentrating mirror and the diametric solar model were established. The radiant flux density on the surface of the receiver for parabolic trough solar concentrator was obtained by numerical calculation with the established models. Charge-coupled device (CCD) was used for testing gray image on the surface of the receiver for parabolic trough solar concentrator. The image was analyzed by Matlab and the radiant flux density on the surface of the receiver for parabolic trough solar concentrator was achieved. It was found that the result of the theory is consistent with that of the experiment, and the relative deviation on the focal length width was 8.7%. The geometrical structure of receiver based on parabolic trough solar concentrator was optimized, a new parabolic receiver has been proposed, and it has been shown that the optimized geometrical structure of receiver was beneficial to improve the working performance of the entire system.

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35

Sokoloff, D. D., V. N., Obridko, I. M., Livshits, and A. S. Shibalova. "Cycle-dependent and cycle-independent surface tracers of solar magnetic activity." Proceedings of the International Astronomical Union 14, A30 (August 2018): 342–43. http://dx.doi.org/10.1017/s1743921319004563.

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AbstractWe consider several tracers of magnetic activity that separate cycle-dependent contributions to the background solar magnetic field from those that are independent of the cycle. The main message is that background fields include two relative separate populations. The background fields with a strength up to 100 Mx cm−2 are very poorly correlated with the sunspot numbers and vary little with the phase of the cycle. In contrast, stronger magnetic fields demonstrate pronounced cyclic behaviour. Small-scale solar magnetic fields demonstrate features of fractal intermittent behaviour, which requires quantification. We investigate how the observational estimate of the solar magnetic flux density B depends on resolution D in order to obtain the scaling In BD = −k In D + a in a reasonably wide range. The quantity k demonstrates cyclic variations typical of a solar activity cycle. k depends on the magnetic flux density, i.e. the ratio of the magnetic flux to the area over which the flux is calculated, at a given instant. The quantity a demonstrates some cyclic variation, but it is much weaker than in the case of k. The scaling is typical of fractal structures. The results obtained trace small-scale action in the solar convective zone and its coexistence with the conventional large-scale solar dynamo based on differential rotation and mirror-asymmetric convection. Here we discuss the message for solar dynamo studies hidden in the above results.

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Varotsos, C. A., S. Lovejoy, N. V. Sarlis, M. N. Efstathiou, and C. G. Tzanis. "On the scaling of the solar incident flux." Atmospheric Chemistry and Physics Discussions 15, no. 7 (April 15, 2015): 10971–86. http://dx.doi.org/10.5194/acpd-15-10971-2015.

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Abstract. It was recently found that spectral solar incident flux (SIF) as a function of the ultraviolet wavelengths exhibits 1/f-type power-law correlations. In this study, an attempt was made to explore the SIF intrinsic dynamics vs. a wider range of wavelengths, from 115.5 to 629.5 nm. It seemed that the intermittency of SIF data set was very high and the revealed DFA-n exponents were close to unity thus again indicating 1/f power-law correlations. Moreover, the power spectral density was fitted algebraically with exponents close to unity. Eliminating the fitting of Planck formula at the Sun's effective temperature from SIF data set, scaling exponents very close to unity were derived, indicating that the 1/f scaling dynamics concern not the Planck's law but its fluctuations.

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Traore, Sada, Idrissa Gaye, Oulimata Mballo, Ibrahima Diatta, Richard Mane, Mor Ndiaye, Mohamed Abderahim El Moujtaba, and Gregoire Sissoko. "MINORITY CARRIERS MOBILITY DETERMINATION IN THE BASE REGION OF N+-P-P+ SILICON SOLAR CELL UNDER EFFECTS OF IRRADIATION FLUX, TEMPERATURE AND MAGNETIC FIELD." International Journal of Advanced Research 9, no. 08 (August 31, 2021): 694–703. http://dx.doi.org/10.21474/ijar01/13317.

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The aim of this study is to show the influence of temperature on the relative value of the short-circuit photocurrent density obtained from an n+-p-p+silicon solar cell front illuminated with modulated polychromatic light. The solar cell was already subjected to charged particules irradiation flux (ÃŽÂ¦p) and intensity (kl,) and remained under both magnetic field (B) and temperature (T). Thus, the graphical representation of the relative value of the short-circuit photocurrent density as a function of the square of the magnetic field (B) yields to determine the slope, which is related to the mobility of minority carriers in the base. It is obtained for a back surface field silicon solar cellunder both temperature and irradiation flux of charged particules.

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Rentz, S., and H. Lühr. "Climatology of the cusp-related thermospheric mass density anomaly, as derived from CHAMP observations." Annales Geophysicae 26, no. 9 (September 18, 2008): 2807–23. http://dx.doi.org/10.5194/angeo-26-2807-2008.

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Abstract. We report on the thermospheric mass density anomaly in the vicinity of the ionospheric cusp. A systematic survey of the anomalies is presented, based on a statistical analysis of 4 years of data (2002–2005) obtained by the accelerometer onboard CHAMP. The anomalies are detected during all years and seasons in both hemispheres but with stronger signatures in the Northern Hemisphere. For the same geophysical conditions, solar flux and geomagnetic activity the anomalies in the north are larger by a factor of about 1.35. Over the course of the survey period the amplitude decreases by more than a factor of 5 while the level of solar flux reduces by a factor of 2. The anomaly strength also depends on the solar wind input. The merging electric field, Emerg, is generally enhanced for about an hour before the anomaly detection. There is a quadratic response of the anomaly amplitude to Emerg. For geophysical conditions of P10.7<150 and Emerg<1 mV/m hardly any events are detected. Their amplitudes are found to be controlled by an additive effect of P10.7 and Emerg, where the weight of Emerg, in mV/m, is by about 50 times higher than that of the solar flux level. The solar zenith angle and the influence of particle precipitation are found to play a minor role as a controlling parameter of seasonal variation. The well-known annual variation of the thermospheric density with a minimum around June also influences the formation of the cusp anomalies. This leads to a clear hemispheric asymmetry with very weak anomalies in the south during June solstice, which is supposed to be a combined effect of the minimum in annual variation and the seasonal decrease of solar insolation in this region.

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Zoennchen, Jochen H., Uwe Nass, Hans J. Fahr, and Jerry Goldstein. "The response of the H geocorona between 3 and 8 Re to geomagnetic disturbances studied using TWINS stereo Lyman-α data." Annales Geophysicae 35, no. 1 (February 1, 2017): 171–79. http://dx.doi.org/10.5194/angeo-35-171-2017.

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Abstract. Circumterrestrial Lyman-α column brightness observations from 3–8 Earth radii (Re) have been used to study temporal density variations in the exospheric neutral hydrogen as response to geomagnetic disturbances of different strength, i.e., Dst peak values between −26 and −147 nT. The data used were measured by the two Lyman-α detectors (LAD1/2) onboard both TWINS satellites between the solar minimum of 2008 and near the solar maximum of 2013. The solar Lyman-α flux at 121.6 nm is resonantly scattered near line center by exospheric H atoms and measured by the TWINS LADs. Along a line of sight (LOS), the scattered LOS-column intensity is proportional to the LOS H column density, assuming optically thin conditions above 3 Re. In the case of the eight analyzed geomagnetic storms we found a significant increase in the exospheric Lyman-α flux between 9 and 23 % (equal to the same increase in H column density ΔnH) compared to the undisturbed case short before the storm event. Even weak geomagnetic storms (e.g., Dst peak values ≥ −41 nT) under solar minimum conditions show increases up to 23 % of the exospheric H densities. The strong H density increase in the observed outer exosphere is also a sign of an enhanced H escape flux during storms. For the majority of the storms we found an average time shift of about 11 h between the time when the first significant dynamic solar wind pressure peak (pSW) hits the Earth and the time when the exospheric Lyman-α flux variation reaches its maximum. The results show that the (relative) exospheric density reaction of ΔnH have a tendency to decrease with increasing peak values of Dst index or the Kp index daily sum. Nevertheless, a simple linear correlation between ΔnH and these two geomagnetic indices does not seem to exist. In contrast, when recovering from the peak back to the undisturbed case, the Kp index daily sum and the ΔnH essentially show the same temporal recovery.

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Luo, Y., X. Du, L. Yang, C. Xu, and Y. Yang. "Study on the Allowable Flux Density for a Solar Central Dual-receiver." Energy Procedia 69 (May 2015): 138–47. http://dx.doi.org/10.1016/j.egypro.2015.03.017.

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Wu, C. S., C. B. Wang, and Q. M. Lu. "Density Depletion in a Coronal Flux Tube Associated With Solar Radio Emission." Solar Physics 235, no. 1-2 (May 2006): 317–29. http://dx.doi.org/10.1007/s11207-006-2068-z.

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42

Shi, Y., E. Zesta, and L. R. Lyons. "Features of energetic particle radial profiles inferred from geosynchronous responses to solar wind dynamic pressure enhancements." Annales Geophysicae 27, no. 2 (February 19, 2009): 851–59. http://dx.doi.org/10.5194/angeo-27-851-2009.

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Abstract. Determination of the radial profile of phase space density of relativistic electrons at constant adiabatic invariants is crucial for identifying the source for them within the outer radiation belt. The commonly used method is to convert flux observed at fixed energy to phase space density at constant first, second and third adiabatic invariants, which requires an empirical global magnetic field model and thus might produce some uncertainties in the final results. From a different perspective, in this paper we indirectly infer the shape of the radial profile of phase space density of relativistic electrons near the geosynchronous region by statistically examining the geosynchronous energetic flux response to 128 solar wind dynamic pressure enhancements during the years 2000 to 2003. We thus avoid the disadvantage of using empirical magnetic field models. Our results show that the flux response is species and energy dependent. For protons and low-energy electrons, the primary response to magnetospheric compression is an increase in flux at geosynchronous orbit. For relativistic electrons, the dominant response is a decrease in flux, which implies that the phase space density decreases toward increasing radial distance at geosynchronous orbit and leads to a local peak inside of geosynchronous orbit. The flux response of protons and non-relativistic electrons could result from a phase density that increases toward increasing radial distance, but this cannot be determined for sure due to the particle energization associated with pressure enhancements. Our results for relativistic electrons are consistent with previous results obtained using magnetic field models, thus providing additional confirmation that these results are correct and indicating that they are not the result of errors in their selected magnetic field model.

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Pereira, A. B., N. A. Villa Nova, and E. Galvani. "Estimation of Global Solar Radiation Flux Density in Brazil from a Single Measurement at Solar Noon." Biosystems Engineering 86, no. 1 (September 2003): 27–34. http://dx.doi.org/10.1016/s1537-5110(03)00081-3.

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Thuillier, G., and S. Bruinsma. "The Mg II index for upper atmosphere modelling." Annales Geophysicae 19, no. 2 (February 28, 2001): 219–28. http://dx.doi.org/10.5194/angeo-19-219-2001.

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Abstract. The solar radio flux at 10.7 cm has been used in upper atmosphere density modelling because of its correlation with EUV radiation and its long and complete observational record. A proxy, the Mg II index, for the solar chromospheric activity has been derived by Heath and Schlesinger (1986) from Nimbus-7 data. This index allows one to describe the changes occurring in solar-activity in the UV Sun spectral irradiance. The use of this new proxy in upper atmosphere density modelling will be considered. First, this is supported by the 99.9% correlation between the solar radio flux (F10.7) and the Mg II index over a period of 19 years with, however, large differences on time scales of days to months. Secondly, correlation between EUV emissions and the Mg II index has been shown recently, suggesting that this last index may also be used to describe the EUV variations. Using the same density dataset, a model was first run with the F10.7 index as a solar forcing function and second, with the Mg II index. Comparison of their respective predictions to partial density data showed a 3–8% higher precision when the modelling uses the Mg II index rather than F10.7. An external validation, by means of orbit computation, resulted in a 20–40% smaller RMS of the tracking residuals. A density dataset spanning an entire solar cycle, together with Mg II data, is required to construct an accurate, unbiased as possible density model.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry; thermosphere – composition and chemistry) – History of geophysics (atmospheric sciences)

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Smith, Alexis, Andrew Cameron, Jane Greaves, Moira Jardine, Glen Langston, and Donald Backer. "Radio cyclotron emission from extra-solar planets." Proceedings of the International Astronomical Union 4, S253 (May 2008): 456–58. http://dx.doi.org/10.1017/s1743921308026926.

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AbstractWe present results from an attempt to detect radio emission from the interaction between a transiting extra-solar planet and its host star. We determine a new upper limit of 47 mJy on the radio flux density from HD 189733b, in the frequency range 327–347 MHz.

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Mangalam, A., and V. Krishan. "Models of Flux Tubes from Constrained Relaxation." International Astronomical Union Colloquium 179 (2000): 299–302. http://dx.doi.org/10.1017/s025292110006471x.

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AbstractWe study the relaxation of a compressible plasma to an equilibrium with flow. The constraints of conservation of mass, energy, angular momentum, cross-helicity and relative magnetic helicity are imposed. Equilibria corresponding to the energy extrema while conserving these invariants for parallel flows yield three classes of solutions and one of them with an increasing radial density profile, relevant to solar flux tubes is presented.

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Müller, S., H. Lühr, and S. Rentz. "Solar and magnetospheric forcing of the low latitude thermospheric mass density as observed by CHAMP." Annales Geophysicae 27, no. 5 (May 6, 2009): 2087–99. http://dx.doi.org/10.5194/angeo-27-2087-2009.

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Abstract. We have studied the dependence of the thermospheric mass density at equatorial latitudes on the influence of various drivers. This statistical study is based on CHAMP accelerometer measurements. Our aim is to delineate the influences of the different contributions. For the isolation of the effects we make use of a dedicated data selection procedure and/or removal of disturbing effects. In a first step all readings are normalised to an altitude of 400 km. For the investigation of the solar influences only magnetically quiet days (Ap≤15) are considered. The dependence on solar flux can well be described by a linear relation within the flux range F10.7=80–240. The slope is twice as steep on the day side as on the night side. The air density exhibits clear annual and semi-annual variations with maxima at the equinoxes and a pronounced minimum around June solstice. The thermosphere maintains during quiet days a day to night mass density ratio very close to 2, which is independent of solar flux level or season. The magnetospheric input causing thermospheric density enhancement can well be parameterised by the am activity index. The low latitude density responds with a delay to changes of the index by about 3 h on the dayside and 4–5 h on the night side. The magnetospheric forcing causes an additive contribution to the quiet-time density, which is linearly correlated with the am index. The slopes of density increases are the same on the day and night sides. We present quantitative expressions for all the dependences. Our results suggest that all the studied forcing terms can be treated as linear combinations of the respective contribution.

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Gent, Frederick A., Ben Snow, Viktor Fedun, and Robertus Erdélyi. "Modelling 3D magnetic networks in a realistic solar atmosphere." Monthly Notices of the Royal Astronomical Society 489, no. 1 (August 21, 2019): 28–35. http://dx.doi.org/10.1093/mnras/stz2066.

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ABSTRACT The magnetic network extending from the photosphere (solar radius ≃ R⊙) to the lower corona ($\mathrm{ R}_\odot +10\, {\rm Mm}$) plays an important role in the heating mechanisms of the solar atmosphere. Here we develop further the models of the authors with realistic open magnetic flux tubes, in order to model more complicated configurations. Closed magnetic loops and combinations of closed and open magnetic flux tubes are modelled. These are embedded within a stratified atmosphere, derived from observationally motivated semi-empirical and data-driven models subject to solar gravity and capable of spanning from the photosphere up into the chromosphere and lower corona. Constructing a magnetic field comprising self-similar magnetic flux tubes, an analytic solution for the kinetic pressure and plasma density is derived. Combining flux tubes of opposite polarity, it is possible to create a steady background magnetic field configuration, modelling a solar atmosphere exhibiting realistic stratification. The result can be applied to the Solar and Heliospheric Observatory Michelson Doppler Imager (SOHO/MDI), Solar Dynamics Observatory Helioseismic and Magnetic Imager (SDO/HMI) and other magnetograms from the solar surface, for which photospheric motions can be simulated to explore the mechanism of energy transport. We demonstrate this powerful and versatile method with an application to HMI data.

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Kojima, Y., K. Fujisawa, and K. Motogi. "The bursting variability of 6.7 GHz methanol maser of G33.641-0.228." Proceedings of the International Astronomical Union 13, S336 (September 2017): 336–37. http://dx.doi.org/10.1017/s1743921317011395.

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AbstractFrom 2014 to 2015, we conducted a total of 469 days observation of the 6.7 GHz methanol maser in a star forming region G33.641-0.228, known to be a bursting maser source. As a result, eleven bursts were detected. On MJD 57364, the flux density grew by more than six times w.r.t the day before. Moreover, during the largest burst, the flux density repeatedly increased and decreased rapidly with time-scale as short as 0.24 day. Since these characteristics of the burst are similar to the solar burst, we speculate that the burst of the 6.7 GHz methanol maser in G33.641-0.228 might occur with a similar mechanism of the solar burst.

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Stansby, D., and T. S. Horbury. "Number density structures in the inner heliosphere." Astronomy & Astrophysics 613 (May 2018): A62. http://dx.doi.org/10.1051/0004-6361/201732567.

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Aims. The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods. We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results. We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions. Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

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Journal articles on the topic 'Solar flux density'

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