WorldWideScience

Sample records for counterstreaming solar wind

  1. Counterstreaming solar wind halo electron events on open field lines?

    Science.gov (United States)

    Gosling, J. T.; Mccomas, D. J.; Phillips, J. L.

    1992-01-01

    Counterstreaming solar wind halo electron events have been identified as a common 1 AU signature of coronal mass ejection events, and have generally been interpreted as indicative of closed magnetic field topologies, i.e., magnetic loops or flux ropes rooted at both ends in the Sun, or detached plasmoids. In this paper we examine the possibility that these events may instead occur preferentially on open field lines, and that counterstreaming results from reflection or injection behind interplanetary shocks or from mirroring from regions of compressed magnetic field farther out in the heliosphere. We conclude that neither of these suggested sources of counterstreaming electron beams is viable and that the best interpretation of observed counterstreaming electron events in the solar wind remains that of passage of closed field structures.

  2. Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations

    Directory of Open Access Journals (Sweden)

    B. Lavraud

    2010-01-01

    Full Text Available Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs in the vicinity of corotating interaction regions (CIRs during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used, but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream, as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1 the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2 that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to

  3. FINE MAGNETIC STRUCTURE AND ORIGIN OF COUNTER-STREAMING MASS FLOWS IN A QUIESCENT SOLAR PROMINENCE

    International Nuclear Information System (INIS)

    Shen, Yuandeng; Liu, Yu; Xu, Zhi; Liu, Zhong; Liu, Ying D.; Chen, P. F.; Su, Jiangtao

    2015-01-01

    We present high-resolution observations of a quiescent solar prominence that consists of a vertical and a horizontal foot encircled by an overlying spine and has ubiquitous counter-streaming mass flows. While the horizontal foot and the spine were connected to the solar surface, the vertical foot was suspended above the solar surface and was supported by a semicircular bubble structure. The bubble first collapsed, then reformed at a similar height, and finally started to oscillate for a long time. We find that the collapse and oscillation of the bubble boundary were tightly associated with a flare-like feature located at the bottom of the bubble. Based on the observational results, we propose that the prominence should be composed of an overlying horizontal spine encircling a low-lying horizontal and vertical foot, in which the horizontal foot consists of shorter field lines running partially along the spine and has ends connected to the solar surface, while the vertical foot consists of piling-up dips due to the sagging of the spine fields and is supported by a bipolar magnetic system formed by parasitic polarities (i.e., the bubble). The upflows in the vertical foot were possibly caused by the magnetic reconnection at the separator between the bubble and the overlying dips, which intruded into the persistent downflow field and formed the picture of counter-streaming mass flows. In addition, the counter-streaming flows in the horizontal foot were possibly caused by the imbalanced pressure at the both ends

  4. Counterstreaming electrons in small interplanetary magnetic flux ropes

    Science.gov (United States)

    Feng, H. Q.; Zhao, G. Q.; Wang, J. M.

    2015-12-01

    Small interplanetary magnetic flux ropes (SIMFRs) are commonly observed by spacecraft at 1 AU, and their origin still remains disputed. We investigated the counterstreaming suprathermal electron (CSE) signatures of 106 SIMFRs measured by Wind during 1995-2005. We found that 79 (75%) of the 106 flux ropes contain CSEs, and the percentages of counterstreaming vary from 8% to 98%, with a mean value of 51%. CSEs are often observed in magnetic clouds (MCs), and this indicates these MCs are still attached to the Sun at both ends. CSEs are also related to heliospheric current sheets (HCSs) and the Earth's bow shock. We divided the SIMFRs into two categories: The first category is far from HCSs, and the second category is in the vicinity of HCSs. The first category has 57 SIMFRs, and only 7 of 57 ropes have no CSEs. This ratio is similar to that of MCs. The second category has 49 SIMFRs; however, 20 of the 49 events have no CSEs. This ratio is larger than that of MCs. These two categories have different origins. One category originates from the solar corona, and most ropes are still connected to the Sun at both ends. The other category is formed near HCSs in the interplanetary space.

  5. Solar wind stagnation near comets

    International Nuclear Information System (INIS)

    Galeev, A.A.; Cravens, T.E.; Gombosi, T.I.

    1983-03-01

    The nature of the solar wind flow near comets is examined analytically. In particular, the typical values for the stagnation pressure and magnetic barrier strength are estimated, taking into account the magnetic field line tension and the charge exchange cooling of the mass loaded solar wind. Knowledge of the strength of the magnetic barrier is required in order to determine the location of the contact discontinuity which separates the contaminated solar wind plasma and the outflowing plasma of the cometary ionosphere. (author)

  6. Solar wind stream interfaces

    International Nuclear Information System (INIS)

    Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

    1978-01-01

    Measurements aboard Imp 6, 7, and 8 reveal that approximately one third of all high-speed solar wind streams observed at 1 AU contain a sharp boundary (of thickness less than approx.4 x 10 4 km) near their leading edge, called a stream interface, which separates plasma of distinctly different properties and origins. Identified as discontinuities across which the density drops abruptly, the proton temperature increases abruptly, and the speed rises, stream interfaces are remarkably similar in character from one stream to the next. A superposed epoch analysis of plasma data has been performed for 23 discontinuous stream interfaces observed during the interval March 1971 through August 1974. Among the results of this analysis are the following: (1) a stream interface separates what was originally thick (i.e., dense) slow gas from what was originally thin (i.e., rare) fast gas; (2) the interface is the site of a discontinuous shear in the solar wind flow in a frame of reference corotating with the sun; (3) stream interfaces occur at speeds less than 450 km s - 1 and close to or at the maximum of the pressure ridge at the leading edges of high-speed streams; (4) a discontinuous rise by approx.40% in electron temperature occurs at the interface; and (5) discontinuous changes (usually rises) in alpha particle abundance and flow speed relative to the protons occur at the interface. Stream interfaces do not generally recur on successive solar rotations, even though the streams in which they are embedded often do. At distances beyond several astronomical units, stream interfaces should be bounded by forward-reverse shock pairs; three of four reverse shocks observed at 1 AU during 1971--1974 were preceded within approx.1 day by stream interfaces. Our observations suggest that many streams close to the sun are bounded on all sides by large radial velocity shears separating rapidly expanding plasma from more slowly expanding plasma

  7. Wind in the Solar System

    Science.gov (United States)

    McIntosh, Gordon

    2010-01-01

    As an astronomy instructor I am always looking for commonly experienced Earthly phenomena to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote short "TPT" articles on frost and precipitation. The present article is on winds in the solar system. A windy day or storm might…

  8. PHOTOIONIZATION IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Landi, E.; Lepri, S. T., E-mail: elandi@umich.edu [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-10-20

    In this work we investigate the effects of photoionization on the charge state composition of the solar wind. Using measured solar EUV and X-ray irradiance, the Michigan Ionization Code and a model for the fast and slow solar wind, we calculate the evolution of the charge state distribution of He, C, N, O, Ne, Mg, Si, S, and Fe with and without including photoionization for both types of wind. We find that the solar radiation has significant effects on the charge state distribution of C, N, and O, causing the ionization levels of these elements to be higher than without photoionization; differences are largest for oxygen. The ions commonly observed for elements heavier than O are much less affected, except in ICMEs where Fe ions more ionized than 16+ can also be affected by the solar radiation. We also show that the commonly used O{sup 7+}/O{sup 6+} density ratio is the most sensitive to photoionization; this sensitivity also causes the value of this ratio to depend on the phase of the solar cycle. We show that the O{sup 7+}/O{sup 6+} ratio needs to be used with caution for solar wind classification and coronal temperature estimates, and recommend the C{sup 6+}/C{sup 4+} ratio for these purposes.

  9. Variation of the solar wind velocity following solar flares

    International Nuclear Information System (INIS)

    Huang, Y.; Lee, Y.

    1975-01-01

    By use of the superposed epoch method, changes in the solar wind velocity following solar flares have been investigated by using the solar wind velocity data obtained by Pioneer 6 and 7 and Vela 3, 4, and 5 satellites. A significant increase of the solar wind velocity has been found on the second day following importance 3 solar flares and on the third day following importance 2 solar flares. No significant increase of the solar wind velocity has been found for limb flares. (auth)

  10. Turbulence in the solar wind

    CERN Document Server

    Bruno, Roberto

    2016-01-01

    This book provides an overview of solar wind turbulence from both the theoretical and observational perspective. It argues that the interplanetary medium offers the best opportunity to directly study turbulent fluctuations in collisionless plasmas. In fact, during expansion, the solar wind evolves towards a state characterized by large-amplitude fluctuations in all observed parameters, which resembles, at least at large scales, the well-known hydrodynamic turbulence. This text starts with historical references to past observations and experiments on turbulent flows. It then introduces the Navier-Stokes equations for a magnetized plasma whose low-frequency turbulence evolution is described within the framework of the MHD approximation. It also considers the scaling of plasma and magnetic field fluctuations and the study of nonlinear energy cascades within the same framework. It reports observations of turbulence in the ecliptic and at high latitude, treating Alfvénic and compressive fluctuations separately in...

  11. Geometry of solar corona expansion and solar wind parameters

    International Nuclear Information System (INIS)

    Krajnev, M.B.

    1980-01-01

    The character of the parameter chanqe of solar wind plasma in the region of the Earth orbit is studied. The main regularities in the parametep behaviour of solar wind (plasma velocity and density) are qualitatively explained in the framework of a model according to which solar corona expansion stronqly differs from radial expansion, that is: the solar wind current lines are focused towards helioequator during the period of low solar activity with gradual transfer to radial expansion during the years of high solar activity. It is shown that the geometry of the solar wind current tubes and its change with the solar activity cycle can not serve an explanation of the observed change of the solar wind parameters

  12. PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Ziebell, L. F.; Petruzzellis, L. T.; Gaelzer, R. [Instituto de Física, UFRGS, Porto Alegre, RS (Brazil); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, MD (United States); Pavan, J., E-mail: luiz.ziebell@ufrgs.br, E-mail: yoonp@umd.edu, E-mail: joel.pavan@ufpel.edu.br [Instituto de Física e Matemática, UFPel, Pelotas, RS (Brazil)

    2016-02-10

    The radiation emission mechanism responsible for both type-II and type-III solar radio bursts is commonly accepted as plasma emission. Recently Ganse et al. suggested that type-II radio bursts may be enhanced when the electron foreshock geometry of a coronal mass ejection contains a double hump structure. They reasoned that the counter-streaming electron beams that exist between the double shocks may enhance the nonlinear coalescence interaction, thereby giving rise to more efficient generation of radiation. Ganse et al. employed a particle-in-cell simulation to study such a scenario. The present paper revisits the same problem with EM weak turbulence theory, and show that the fundamental (F) emission is not greatly affected by the presence of counter-streaming beams, but the harmonic (H) emission becomes somewhat more effective when the two beams are present. The present finding is thus complementary to the work by Ganse et al.

  13. 77 FR 61597 - Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind...

    Science.gov (United States)

    2012-10-10

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-109-000] Avalon Wind, LLC; Avalon Wind 2, LLC; Catalina Solar, LLC; Catalina Solar 2, LLC; Pacific Wind Lessee, LLC; Pacific Wind 2, LLC; Valentine Solar, LLC; EDF Renewable Development, Inc.; Notice of Petition for Declaratory...

  14. Distributed Wind Cost Reduction: Learning from Solar

    Energy Technology Data Exchange (ETDEWEB)

    Tegen, Suzanne

    2016-02-23

    The distributed wind energy industry can learn several lessons from the solar industry regarding reducing soft costs. Suzanne Tegen presented this overview at the 2016 Distributed Wind Energy Association Business Conference in Washington, D.C., on February 23, 2016.

  15. Astrospheres and Solar-like Stellar Winds

    Directory of Open Access Journals (Sweden)

    Wood Brian E.

    2004-07-01

    Full Text Available Stellar analogs for the solar wind have proven to be frustratingly difficult to detect directly. However, these stellar winds can be studied indirectly by observing the interaction regions carved out by the collisions between these winds and the interstellar medium (ISM. These interaction regions are called "astrospheres", analogous to the "heliosphere" surrounding the Sun. The heliosphere and astrospheres contain a population of hydrogen heated by charge exchange processes that can produce enough H I Ly alpha absorption to be detectable in UV spectra of nearby stars from the Hubble Space Telescope (HST. The amount of astrospheric absorption is a diagnostic for the strength of the stellar wind, so these observations have provided the first measurements of solar-like stellar winds. Results from these stellar wind studies and their implications for our understanding of the solar wind are reviewed here. Of particular interest are results concerning the past history of the solar wind and its impact on planetary atmospheres.

  16. Solar Wind Earth Exchange Project (SWEEP)

    Science.gov (United States)

    2016-10-28

    highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the...Newton, an X-ray astronomical observatory. We use OMNI solar wind conditions, heavy ion composition data from ACE, the Hodges neutral hydrogen model...of SWEEP was to compare theoretical models of X-ray emission in the terrestrial magnetosphere caused by the Solar Wind Charge Exchange

  17. SUNWARD PROPAGATING ALFVÉN WAVES IN ASSOCIATION WITH SUNWARD DRIFTING PROTON BEAMS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiansen; Pei, Zhongtian; Wang, Linghua; Tu, Chuanyi; Zhang, Lei [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Salem, Chadi, E-mail: jshept@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2015-06-01

    Using measurements from the WIND spacecraft, here we report the observation of sunward propagating Alfvén waves (AWs) in solar wind that is magnetically disconnected from the Earth's bow shock. In the sunward magnetic field sector, we find a period lasting for more than three days in which there existed (during most time intervals) a negative correlation between the flow velocity and magnetic field fluctuations, thus indicating that the related AWs are mainly propagating sunward. Simultaneous observations of counter-streaming suprathermal electrons suggest that these sunward AWs may not simply be due to the deflection of an open magnetic field line. Moreover, no interplanetary coronal mass ejection appears to be associated with the counter-streaming suprathermal electrons. As the scale goes from the magnetohydrodynamic down to the ion kinetic regime, the wave vector of magnetic fluctuations usually becomes more orthogonal to the mean magnetic field direction, and the fluctuations become increasingly compressible, which are both features consistent with quasi-perpendicular kinetic AWs. However, in the case studied here, we find clear signatures of quasi-parallel sunward propagating ion-cyclotron waves. Concurrently, the solar wind proton velocity distribution reveals a sunward field-aligned beam that drifts at about the local Alfvén speed. This beam is found to run in the opposite direction of the normally observed (anti-sunward) proton beam, and is apparently associated with sunward propagating Alfvén/ion-cyclotron waves. The results and conclusions of this study enrich our knowledge of solar wind turbulence and foster our understanding of proton heating and acceleration within a complex magnetic field geometry.

  18. Solar wind radiation damage in lunar dust grains and the characteristics of the ancient solar wind

    International Nuclear Information System (INIS)

    Borg, J.; Chaumont, J.

    1980-01-01

    Current understanding of the exposure history of lunar dust grains to the ancient solar wind is reviewed, the work being based mostly on a Monte Carlo statistical code, describing the 'gardening' effects of the meteorite bombardment in the lunar regolith, and on analytical models, yielding the lifetimes of the grains against various types of destruction processes. Families of lunar dust grains are identified, and evidence is presented showing that lunar dust grains were not partially shielded from solar wind ions. Results of solar wind simulation experiments are used to interpret the thickness distribution of the amorphous coatings of solar wind radiation-damaged material observed on 1-micron lunar dust grains. It is argued that such distributions reflect the speed distribution of the ancient solar wind as averaged over periods of approximately 5000 years in duration, and that the ancient solar wind is less energetic than the present day solar wind

  19. Verification of high-speed solar wind stream forecasts using operational solar wind models

    DEFF Research Database (Denmark)

    Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.

    2016-01-01

    and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat......High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate...... high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation...

  20. Limitation of solar energy and wind energy

    International Nuclear Information System (INIS)

    White, R. S.

    2008-01-01

    Wind turbines, solar energy collectors and photovoltaic cells have been popular sources of electricity since the oil crisis in the late seventies, and they are increasingly favored by many scientists and much of the public as methods for reducing global warming. The older wind farms in California are outdated. New wind turbines have not followed, primarily because of competition from lower-cost natural gas. The Times urges increased federal and state subsidies for the wind and solar industries. The primary reason that wind and solar energies have not made inroads in the past, and will never supply more than a few percentage points of the world's electrical energy, is their unpredictable variations in time and their constant need for back-ups. The only non-carbon-dioxide-emitting generator capable of backing up wind and solar energy and replacing coal and gas generators is nuclear fission. Nuclear power may be the practical solution to global warming, after all.

  1. Solar energy system with wind vane

    Science.gov (United States)

    Grip, Robert E

    2015-11-03

    A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane.

  2. Solar winds along curved magnetic field lines

    OpenAIRE

    Li, Bo; Xia, Li-Dong; Chen, Yao

    2011-01-01

    Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present what makes the fast wind fast and the slow wind slow still remains to be answered. While a robust empirical correlation exists between the coronal expansion rate $f_c$ of the flow tubes and the speeds $v$ measured in situ, further data analysis suggests that $v$ depends on ...

  3. Sneaking of the Solar Wind Ions Into the Lunar Anti-subsolar Region Revealed by SELENE (Kaguya)

    Science.gov (United States)

    Nishino, M. N.; Fujimoto, M.; Saito, Y.; Shoichiro, Y.; Asamura, K.; Tanaka, T.; Tsunakawa, H.; Shibuya, H.; Matsushima, M.; Shimizu, H.; Takahashi, F.; Maezawa, K.; Terasawa, T.

    2008-12-01

    The moon spends more than 80 percent of its life staying in the solar wind (SW), where a quasi-vacuum region called the lunar wake is formed on the night side. The SW electrons with higher energy can come to the lunar night-side surface, while it has been thought that the SW ions are unlikely to approach the low altitude region on the night side because their thermal speed is much lower than the SW bulk speed. Here we show detection of SW ions sneaking into the anti-subsolar region at ~100 km altitude, using recent comprehensive measurement by a Japanese lunar orbiter SELENE (Kaguya). The sneaking of SW ions into the deepest lunar wake was accompanied by an enhancement of counter-streaming electrons along the SW magnetic field. A part of the ions detected in the anti-subsolar region came from the lunar surface, which means that the ions of solar wind origin reflected at the night-side surface. One possibility is that electron- rich wake environment strengthened the bipolar electric field at the wake boundary to let solar-wind ions approach the lunar night side, and the other scenario is that enhancement of ions in the wake let ambient electrons to come in. The sneaking mechanism of the solar wind ions in terms of plasma and electromagnetic environment around/inside the lunar wake will be discussed.

  4. Solar wind classification from a machine learning perspective

    Science.gov (United States)

    Heidrich-Meisner, V.; Wimmer-Schweingruber, R. F.

    2017-12-01

    It is a very well known fact that the ubiquitous solar wind comes in at least two varieties, the slow solar wind and the coronal hole wind. The simplified view of two solar wind types has been frequently challenged. Existing solar wind categorization schemes rely mainly on different combinations of the solar wind proton speed, the O and C charge state ratios, the Alfvén speed, the expected proton temperature and the specific proton entropy. In available solar wind classification schemes, solar wind from stream interaction regimes is often considered either as coronal hole wind or slow solar wind, although their plasma properties are different compared to "pure" coronal hole or slow solar wind. As shown in Neugebauer et al. (2016), even if only two solar wind types are assumed, available solar wind categorization schemes differ considerably for intermediate solar wind speeds. Thus, the decision boundary between the coronal hole and the slow solar wind is so far not well defined.In this situation, a machine learning approach to solar wind classification can provide an additional perspective.We apply a well-known machine learning method, k-means, to the task of solar wind classification in order to answer the following questions: (1) How many solar wind types can reliably be identified in our data set comprised of ten years of solar wind observations from the Advanced Composition Explorer (ACE)? (2) Which combinations of solar wind parameters are particularly useful for solar wind classification?Potential subtypes of slow solar wind are of particular interest because they can provide hints of respective different source regions or release mechanisms of slow solar wind.

  5. Wind and solar resource data sets

    DEFF Research Database (Denmark)

    Clifton, Andrew; Hodge, Bri-Mathias; Draxl, Caroline

    2017-01-01

    The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used...... to support continental-scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used...... for their creation and validation. A brief history of wind and solar resource data sets is then presented, followed by areas for future research. For further resources related to this article, please visit the WIREs website....

  6. Solar and Wind Site Screening Decision Trees

    Science.gov (United States)

    EPA and NREL created a decision tree to guide state and local governments and other stakeholders through a process for screening sites for their suitability for future redevelopment with solar photovoltaic (PV) energy and wind energy.

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

    Science.gov (United States)

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

    2013-01-01

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

  8. Wind loads on solar energy roofs

    NARCIS (Netherlands)

    Geurts, C.P.W.; Bentum, C.A. van

    2007-01-01

    This paper presents an overview of the wind loads on roofs, equipped with solar energy products, so called Active Roofs. Values given in this paper have been based on wind tunnel and full scale measurements, carried out at TNO, and on an interpretation of existing rules and guidelines. The results

  9. Counter-streaming flows in a giant quiet-Sun filament observed in the extreme ultraviolet

    Science.gov (United States)

    Diercke, A.; Kuckein, C.; Verma, M.; Denker, C.

    2018-03-01

    Aim. The giant solar filament was visible on the solar surface from 2011 November 8-23. Multiwavelength data from the Solar Dynamics Observatory (SDO) were used to examine counter-streaming flows within the spine of the filament. Methods: We use data from two SDO instruments, the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI), covering the whole filament, which stretched over more than half a solar diameter. Hα images from the Kanzelhöhe Solar Observatory (KSO) provide context information of where the spine of the filament is defined and the barbs are located. We apply local correlation tracking (LCT) to a two-hour time series on 2011 November 16 of the AIA images to derive horizontal flow velocities of the filament. To enhance the contrast of the AIA images, noise adaptive fuzzy equalization (NAFE) is employed, which allows us to identify and quantify counter-streaming flows in the filament. We observe the same cool filament plasma in absorption in both Hα and EUV images. Hence, the counter-streaming flows are directly related to this filament material in the spine. In addition, we use directional flow maps to highlight the counter-streaming flows. Results: We detect counter-streaming flows in the filament, which are visible in the time-lapse movies in all four examined AIA wavelength bands (λ171 Å, λ193 Å, λ304 Å, and λ211 Å). In the time-lapse movies we see that these persistent flows lasted for at least two hours, although they became less prominent towards the end of the time series. Furthermore, by applying LCT to the images we clearly determine counter-streaming flows in time series of λ171 Å and λ193 Å images. In the λ304 Å wavelength band, we only see minor indications for counter-streaming flows with LCT, while in the λ211 Å wavelength band the counter-streaming flows are not detectable with this method. The diverse morphology of the filament in Hα and EUV images is caused by different absorption

  10. Manifestation of solar activity in solar wind particle flux density

    International Nuclear Information System (INIS)

    Kovalenko, V.A.

    1988-01-01

    An analysis has been made of the origin of long-term variations in flux density of solar wind particles (nv) for different velocity regimes. The study revealed a relationship of these variations to the area of the polar coronal holes (CH). It is shown that within the framework of the model under development, the main longterm variations of nv are a result of the latitude redistribution of the solar wind mass flux in the heliosphere and are due to changes in the large-scale geometry of the solar plasma flow in the corona. A study has been made of the variations of nv for high speed solar wind streams. It is found that nv in high speed streams which are formed in CH, decreases from minimum to maximum solar activity. The analysis indicates that this decrease is attributable to the magnetic field strength increase in coronal holes. It has been found that periods of rapid global changes of background magnetic fields on the Sun are accompanied by a reconfiguration of coronal magnetic fields, rapid changes in the length of quiescent filaments, and by an increase in the density of the particle flux of a high speed solar wind. It has been established that these periods precede the formation of CH, corresponding to the increase in solar wind velocity near the Earth and to enhancement of the level of geomagnetic disturbance. (author)

  11. The Solar Wind Environment in Time

    Science.gov (United States)

    Pognan, Quentin; Garraffo, Cecilia; Cohen, Ofer; Drake, Jeremy J.

    2018-03-01

    We use magnetograms of eight solar analogs of ages 30 Myr–3.6 Gyr obtained from Zeeman Doppler Imaging and taken from the literature, together with two solar magnetograms, to drive magnetohydrodynamical wind simulations and construct an evolutionary scenario of the solar wind environment and its angular momentum loss rate. With observed magnetograms of the radial field strength as the only variant in the wind model, we find that a power-law model fitted to the derived angular momentum loss rate against time, t, results in a spin-down relation Ω ∝ t ‑0.51, for angular speed Ω, which is remarkably consistent with the well-established Skumanich law Ω ∝ t ‑0.5. We use the model wind conditions to estimate the magnetospheric standoff distances for an Earth-like test planet situated at 1 au for each of the stellar cases, and to obtain trends of minimum and maximum wind ram pressure and average ram pressure in the solar system through time. The wind ram pressure declines with time as \\overline{{P}ram}}\\propto {t}2/3, amounting to a factor of 50 or so over the present lifetime of the solar system.

  12. Wind and solar energy incentives in Iran

    International Nuclear Information System (INIS)

    Taleghani, G.; Kazemi Karegar, H.

    2006-01-01

    Incentive have yet been viewed as a means of supporting technological developments until a new technology becomes cost competitive wind based electricity is not jet generally competitive with alternate sources of electricity such as fossil fuels. This paper presents the potential for wind and solar in Iran and shows how much electric energy is now produced by renewable power plants compared to steam and gas. The importance of renewable energy effects on Iran environment and economy is also discussed and the issue of the contribution of renewable energy for producing electricity in the future will be shown. Also this paper highlights the ability of Iran to manufacture the components of the wind turbine and solar system locally, and its effect on the price of wind turbine and solar energy

  13. Clouds blown by the solar wind

    International Nuclear Information System (INIS)

    Voiculescu, M; Condurache-Bota, S; Usoskin, I

    2013-01-01

    In this letter we investigate possible relationships between the cloud cover (CC) and the interplanetary electric field (IEF), which is modulated by the solar wind speed and the interplanetary magnetic field. We show that CC at mid–high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Thus, our results suggest that mid–high latitude clouds might be affected by the solar wind via the GEC. Since IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others. (letter)

  14. Ion acoustic waves in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Frank, L.A.

    1978-01-01

    Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

  15. Solar Illumination Control of the Polar Wind

    Science.gov (United States)

    Maes, L.; Maggiolo, R.; De Keyser, J.; André, M.; Eriksson, A. I.; Haaland, S.; Li, K.; Poedts, S.

    2017-11-01

    Polar wind outflow is an important process through which the ionosphere supplies plasma to the magnetosphere. The main source of energy driving the polar wind is solar illumination of the ionosphere. As a result, many studies have found a relation between polar wind flux densities and solar EUV intensity, but less is known about their relation to the solar zenith angle at the ionospheric origin, certainly at higher altitudes. The low energy of the outflowing particles and spacecraft charging means it is very difficult to measure the polar wind at high altitudes. We take advantage of an alternative method that allows estimations of the polar wind flux densities far in the lobes. We analyze measurements made by the Cluster spacecraft at altitudes from 4 up to 20 RE. We observe a strong dependence on the solar zenith angle in the ion flux density and see that both the ion velocity and density exhibit a solar zenith angle dependence as well. We also find a seasonal variation of the flux density.

  16. Laboratory Facility for Simulating Solar Wind Sails

    International Nuclear Information System (INIS)

    Funaki, Ikkoh; Ueno, Kazuma; Oshio, Yuya; Ayabe, Tomohiro; Horisawa, Hideyuki; Yamakawa, Hiroshi

    2008-01-01

    Magnetic sail (MagSail) is a deep space propulsion system, in which an artificial magnetic cavity captures the energy of the solar wind to propel a spacecraft in the direction leaving the sun. For a scale-model experiment of the plasma flow of MagSail, we employed a magnetoplasmadynamic arcjet as a solar wind simulator. It is observed that a plasma flow from the solar wind simulator reaches a quasi-steady state of about 0.8 ms duration after a transient phase when initiating the discharge. During this initial phase of the discharge, a blast-wave was observed to develop radially in a vacuum chamber. When a solenoidal coil (MagSail scale model) is immersed into the quasi-steady flow where the velocity is 45 km/s, and the number density is 10 19 m-3, a bow shock as well as a magnetic cavity were formed in front of the coil. As a result of the interaction between the plasma flow and the magnetic cavity, the momentum of the simulated solar wind is decreased, and it is found from the thrust measurement that the solar wind momentum is transferred to the coil simulating MagSail.

  17. Solar-wind minor ions: recent observations

    International Nuclear Information System (INIS)

    Bame, S.J.

    1982-01-01

    During the years following the Solar Wind Four Conference at Burghausen our knowledge of the solar wind ion composition and dynamics has grown. There have been some surprises, and our understanding of the evolution of the solar wind has been improved. Systematic studies have shown that the minor ions generally travel with a common bulk speed and have temperatures roughly proportional to their masses. It has been determined that the 3 He ++ content varies greatly; 3 He ++ / 4 He ++ ranges from as high as 10 2 values to below 2 x 10 - 4 . In some solar wind flows which can be related to energetic coronal events, the minor ions are found in unusual ionization states containing Fe 16 + as a prominent ion, showing that the states were formed at unusually high temperatures. Unexpectedly, in a few flows substantial quantities of 4 He + have been detected, sometimes with ions identifiable as O 2 + and O 3 + . Surprisingly, in some of these examples the ionization state is mixed showing that part of the plasma escaped the corona without attaining the usual million-degree temperatures while other parts were heated more nearly in the normal manner. Additionally, detailed studies of the minor ions have increased our understanding of the coronal expansion. For example, such studies have contributed to identifying near equatorial coronal streamers as the source of solar wind flows between high speed streams

  18. ENERGY DISSIPATION PROCESSES IN SOLAR WIND TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Wei, F. S.; Feng, X. S.; Sun, T. R.; Zuo, P. B. [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Xu, X. J. [Space Science Institute, Macau University of Science and Technology, Macao (China); Zhang, J., E-mail: yw@spaceweather.ac.cn [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, MSN 3F3, Fairfax, Virginia 22030 (United States)

    2015-12-15

    Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.

  19. Solar wind controlled pulsations: A review

    International Nuclear Information System (INIS)

    Odera, T.J.

    1986-01-01

    Studies of the solar wind controlled Pc 3, 4 pulsations by early and recent researchers are highlighted. The review focuses on the recent observations, which cover the time during the International Magnetospheric Study (IMS). Results from early and recent observations agree on one point, that is, that the Pc 3, 4 pulsations are influenced by three main solar wind parameters, namely, the solar wind velocity V/sub 5w/, the IMF orientation theta/sub x/B, and magnitude B. The results can be interpreted, preferably, in terms of an external origin for Pc 3, 4 pulsations. This implies, essentially, the signal model, which means that the pulsations originate in the upstream waves (in the interplanetary medium) and are transported by convection to the magnetopause, where they couple to oscillations of the magnetospheric field lines

  20. Diagnostics of the solar wind transition region

    International Nuclear Information System (INIS)

    Lotova, N.A.; Nagelis, Ya.V.; Rudnitskij, G.M.; Smirnova, T.V.; AN Latvijskoj SSR, Riga. Radioastrofizicheskaya Observatoriya; Moskovskij Gosudarstvennyj Univ.; AN SSSR, Moscow. Fizicheskij Inst.)

    1988-01-01

    Possibilities are discussed of a more complete study of hardly observable regions of the interplanetary medium, in the zone of the solar wind formation, where transition from subsonic to supersonic flow occurs at R sun . It is shown that an investigation of fine structure of the extended transonic region of the solar wind and of the sequence of changes in the parameters of the interplanetary plasma in the region of the solar wind formation with the changing distance from the Sun can be effectuated by using jointly different modifications of the occupation method. Combination of two or more modifications of this method supposes using compact radio sources of different classes and observations in two different wavelength ranges, namely at short centimeter and at meter waves

  1. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    1999-03-01

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined by the proton temperature and by the direction of the magnetic field, which themselves depend on the latitude of WIND with respect to the heliospheric current sheet.Key words

  2. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined

  3. Combined wind and solar feed-in to the grid

    CSIR Research Space (South Africa)

    Mushwana, Crescent

    2018-05-01

    Full Text Available This presentation highlights South African wind and solar resources and presents a case study on wind and solar PV combination. It also distinguishes between traditional and new philosophies regarding energy system design and the changes...

  4. Wind/solar resource in Texas

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, V.; Starcher, K.; Gaines, H. [West Texas A& M Univ., Canyon, TX (United States)

    1997-12-31

    Data are being collected at 17 sites to delineate a baseline for the wind and solar resource across Texas. Wind data are being collected at 10, 25, and 40 m (in some cases at 50 m) to determine wind shear and power at hub heights of large turbines. Many of the sites are located in areas of predicted terrain enhancement. The typical day in a month for power and wind turbine output was calculated for selected sites and combination of sites; distributed systems. Major result to date is that there is the possibility of load matching in South Texas during the summer months, even though the average values by month indicate a low wind potential.

  5. Numerical simulation of wind loads on solar panels

    Science.gov (United States)

    Su, Kao-Chun; Chung, Kung-Ming; Hsu, Shu-Tsung

    2018-05-01

    Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect.

  6. Counterstreaming magnetized plasmas. II. Perpendicular wave propagation

    International Nuclear Information System (INIS)

    Tautz, R.C.; Schlickeiser, R.

    2006-01-01

    The properties of longitudinal and transverse oscillations in magnetized symmetric counterstreaming Maxwellian plasmas with equal thermal velocities for waves propagating perpendicular to the stream direction are investigated on the basis of Maxwell equations and the nonrelativistic Vlasov equation. With the constraint of vanishing particle flux in the stream direction, three distinct dispersion relations are known, which are the ordinary-wave mode, the Bernstein wave mode, and the extraordinary electromagnetic wave mode, where the latter two are only approximations. In this article, all three dispersion relations are evaluated for a counterstreaming Maxwellian distribution function in terms of the hypergeometric function 2 F 2 . The growth rates for the ordinary-wave mode are compared to earlier results by Bornatici and Lee [Phys. Fluids 13, 3007 (1970)], who derived approximate results, whereas in this article the exact dispersion relation is solved numerically. The original results are therefore improved and show differences of up to 21% to the results obtained in this article

  7. Combined Ulysses Solar Wind and SOHO Coronal Observations of Several West Limb Coronal Mass Ejections. Appendix 8

    Science.gov (United States)

    Funsten, H. O.; Gosling, J. T.; Riley, P.; St.Cyr, O. C.; Forsyth, R. J.; Howard, R. A.; Schwenn, R.

    2001-01-01

    From October 1996 to January 1997, Ulysses was situated roughly above the west limb of the Sun as observed from Earth at a heliocentric distance of about 4.6 AU and a latitude of about 25 deg. This presents the first opportunity to compare Solar and Heliospheric Observatory (SOHO) limb observations of coronal mass ejections (CMEs) directly with their solar wind counterparts far from the Sun using the Ulysses data. During this interval, large eruptive events were observed above the west limb of the Sun by the Large Angle Spectrometric Coronagraph (LASCO) on SOHO on October 5, November 28, and December 21-25, 1996. Using the combined plasma and magnetic field data from Ulysses, the October 5 event was clearly identified by several distinguishing signatures as a CME. The November 28 event was also identified as a CME that trailed fast ambient solar wind, although it was identified only by an extended interval of counterstreaming suprathermal electrons. The December 21 event was apparently characterized by a six-day interval of nearly radial field and a plasma rarefaction. For the numerous eruptive events observed by the LASCO coronagraph during December 23-25, Ulysses showed no distinct, CMEs, perhaps because of intermingling of two or more of the eruptive events. By mapping the Ulysses observations back in time to the Sun assuming a constant flow speed, we have identified intervals of plasma that were accelerated or decelerated between the LASCO and Ulysses observations.

  8. Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

    Science.gov (United States)

    Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F.

    2007-08-01

    We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum.

  9. The Solar Wind as a Turbulence Laboratory

    Directory of Open Access Journals (Sweden)

    Vincenzo Carbone

    2013-05-01

    Full Text Available In this review we will focus on a topic of fundamental importance for both astrophysics and plasma physics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research field will be reported emphasizing the results obtained in the past decade or so. As a matter of fact, Helios inner heliosphere and Ulysses' high latitude observations, recent multi-spacecrafts measurements in the solar wind (Cluster four satellites and new numerical approaches to the problem, based on the dynamics of complex systems, brought new important insights which helped to better understand how turbulent fluctuations behave in the solar wind. In particular, numerical simulations within the realm of magnetohydrodynamic (MHD turbulence theory unraveled what kind of physical mechanisms are at the basis of turbulence generation and energy transfer across the spectral domain of the fluctuations. In other words, the advances reached in these past years in the investigation of solar wind turbulence now offer a rather complete picture of the phenomenological aspect of the problem to be tentatively presented in a rather organic way.

  10. Energy Primer: Solar, Water, Wind, and Biofuels.

    Science.gov (United States)

    Portola Inst., Inc., Menlo Park, CA.

    This is a comprehensive, fairly technical book about renewable forms of energy--solar, water, wind, and biofuels. The biofuels section covers biomass energy, agriculture, aquaculture, alcohol, methane, and wood. The focus is on small-scale systems which can be applied to the needs of the individual, small group, or community. More than one-fourth…

  11. Identifying Wind and Solar Ramping Events: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Florita, A.; Hodge, B. M.; Orwig, K.

    2013-01-01

    Wind and solar power are playing an increasing role in the electrical grid, but their inherent power variability can augment uncertainties in power system operations. One solution to help mitigate the impacts and provide more flexibility is enhanced wind and solar power forecasting; however, its relative utility is also uncertain. Within the variability of solar and wind power, repercussions from large ramping events are of primary concern. At the same time, there is no clear definition of what constitutes a ramping event, with various criteria used in different operational areas. Here the Swinging Door Algorithm, originally used for data compression in trend logging, is applied to identify variable generation ramping events from historic operational data. The identification of ramps in a simple and automated fashion is a critical task that feeds into a larger work of 1) defining novel metrics for wind and solar power forecasting that attempt to capture the true impact of forecast errors on system operations and economics, and 2) informing various power system models in a data-driven manner for superior exploratory simulation research. Both allow inference on sensitivities and meaningful correlations, as well as the ability to quantify the value of probabilistic approaches for future use in practice.

  12. Classification of solar wind with machine learning

    NARCIS (Netherlands)

    E. Camporeale (Enrico); A. Carè (Algo); J.E. Borovsky (Joseph)

    2017-01-01

    htmlabstractWe present a four-category classification algorithm for the solar wind, based on Gaussian Process. The four categories are the ones previously adopted in Xu and Borovsky (2015): ejecta, coronal hole origin plasma, streamer belt origin plasma, and sector reversal origin plasma. The

  13. Mirror Instability in the Turbulent Solar Wind

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Landi, S.; Matteini, L.; Verdini, A.; Franci, L.

    2017-01-01

    Roč. 838, č. 2 (2017), 158/1-158/7 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : instabilities * solar wind * waves Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.533, year: 2016

  14. Solar wind conditions for a quiet magnetosphere

    International Nuclear Information System (INIS)

    Kerns, K.J.; Gussenhoven, M.S.

    1990-01-01

    The conditions of the solar wind that lead to a quiet magnetosphere are determined under the assumption that the quiet or baseline magnetosphere can be identified by prolonged periods of low values of the am index. The authors analyzed solar wind data from 1978 to 1984 (7 years) during periods in which am ≤ 3 nT to identify those solar wind parameters that deviate significantly from average values. Parallel studies were also performed for prolonged periods of Kp = 0, 0+ and AE z ) show distinctive variations from average values. They independently varied these solar wind parameters and the length of time the conditions must persist to minimize am. This was done with the additional requirement that the conditions yield a reasonable number of occurrences (5% of the data set). The resulting baseline conditions are V ≤ 390 km/s; 180 degree - arctan |B y /B z | ≤ 101 degree, when b z ≤ 0 (no restriction on B z positive); B ≤ 6.5 nT; and persistence of these conditions for at least 5 hours. Minimizing the am index does not require a clear upper limit on the value of B z as might be anticipated from the work of Gussenhoven (1988) and Berthelier (1980). Apparently, this is a result of the requirement that the conditions must occur 5% of the time. When the requirement is lowered to 1% occurrence, an upper limit to B z emerges

  15. Modeling 3-D solar wind structure

    Czech Academy of Sciences Publication Activity Database

    Odstrčil, Dušan

    2003-01-01

    Roč. 32, č. 4 (2003), s. 497-506 ISSN 0273-1177 R&D Projects: GA AV ČR IAA3003003; GA AV ČR IBS1003006 Institutional research plan: CEZ:AV0Z1003909 Keywords : solar wind * modeling Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.483, year: 2003

  16. Wind and solar resource data sets: Wind and solar resource data sets

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, Andrew [National Renewable Energy Laboratory, Golden CO USA; Hodge, Bri-Mathias [National Renewable Energy Laboratory, Golden CO USA; Power Systems Engineering Center, National Renewable Energy Laboratory, Golden CO USA; Draxl, Caroline [National Renewable Energy Laboratory, Golden CO USA; National Wind Technology Center, National Renewable Energy Laboratory, Golden CO USA; Badger, Jake [Department of Wind Energy, Danish Technical University, Copenhagen Denmark; Habte, Aron [National Renewable Energy Laboratory, Golden CO USA; Power Systems Engineering Center, National Renewable Energy Laboratory, Golden CO USA

    2017-12-05

    The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used to support continental-scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used for their creation and validation. A brief history of wind and solar resource data sets is then presented, followed by areas for future research.

  17. Intermittency Statistics in the Expanding Solar Wind

    Science.gov (United States)

    Cuesta, M. E.; Parashar, T. N.; Matthaeus, W. H.

    2017-12-01

    The solar wind is observed to be turbulent. One of the open questions in solar wind research is how the turbulence evolves as the solar wind expands to great distances. Some studies have focused on evolution of the outer scale but not much has been done to understand how intermittency evolves in the expanding wind beyond 1 AU (see [1,2]). We use magnetic field data from Voyager I spacecraft from 1 to 10AU to study the evolution of statistics of magnetic discontinuities. We perform various statistical tests on these discontinuities and make connections to the physical processes occurring in the expanding wind.[1] Tsurutani, Bruce T., and Edward J. Smith. "Interplanetary discontinuities: Temporal variations and the radial gradient from 1 to 8.5 AU." Journal of Geophysical Research: Space Physics 84.A6 (1979): 2773-2787.[2] Greco, A., et al. "Evidence for nonlinear development of magnetohydrodynamic scale intermittency in the inner heliosphere." The Astrophysical Journal 749.2 (2012): 105.

  18. Kinetic Physics of the Solar Corona and Solar Wind

    Directory of Open Access Journals (Sweden)

    Marsch Eckart

    2006-07-01

    Full Text Available Kinetic plasma physics of the solar corona and solar wind are reviewed with emphasis on the theoretical understanding of the in situ measurements of solar wind particles and waves, as well as on the remote-sensing observations of the solar corona made by means of ultraviolet spectroscopy and imaging. In order to explain coronal and interplanetary heating, the microphysics of the dissipation of various forms of mechanical, electric and magnetic energy at small scales (e.g., contained in plasma waves, turbulences or non-uniform flows must be addressed. We therefore scrutinise the basic assumptions underlying the classical transport theory and the related collisional heating rates, and also describe alternatives associated with wave-particle interactions. We elucidate the kinetic aspects of heating the solar corona and interplanetary plasma through Landau- and cyclotron-resonant damping of plasma waves, and analyse in detail wave absorption and micro instabilities. Important aspects (virtues and limitations of fluid models, either single- and multi-species or magnetohydrodynamic and multi-moment models, for coronal heating and solar wind acceleration are critically discussed. Also, kinetic model results which were recently obtained by numerically solving the Vlasov–Boltzmann equation in a coronal funnel and hole are presented. Promising areas and perspectives for future research are outlined finally.

  19. Electric solar wind sail mass budget model

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2013-02-01

    Full Text Available The electric solar wind sail (E-sail is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

  20. Wind and IMP 8 Solar Wind, Magnetosheath and Shock Data

    Science.gov (United States)

    2004-01-01

    The purpose of this project was to provide the community access to magnetosheath data near Earth. We provided 27 years of IMP 8 magnetosheath proton velocities, densities, and temperatures with our best (usually 1-min.) time resolution. IMP 8 crosses the magnetosheath twice each 125 day orbit, and we provided magnetosheath data for the roughly 27 years of data for which magnetometer data are also available (which are needed to reliably pick boundaries). We provided this 27 years of IMP 8 magnetosheath data to the NSSDC; this data is now integrated with the IMP 8 solar wind data with flags indicating whether each data point is in the solar wind, magnetosheath, or at the boundary between the two regions. The plasma speed, density, and temperature are provided for each magnetosheath point. These data are also available on the MIT web site ftp://space .mit.edu/pub/plasma/imp/www/imp.html. We provide ASCII time-ordered rows of data giving the observation time, the spacecraft position in GSE, the velocity is GSE, the density and temperature for protons. We also have analyzed and archived on our web site the Wind magnetosheath plasma parameters. These consist of ascii files of the proton and alpha densities, speeds, and thermal speeds. These data are available at ftp://space.mit.edu/pub/plasma/wind/sheath These are the two products promised in the work statement and they have been completed in full.

  1. Extending Counter-streaming Motion from an Active Region Filament to a Sunspot Light Bridge

    Science.gov (United States)

    Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu, Yan; Jing, Ju; Wang, Yuming; Cao, Wenda

    2018-01-01

    We analyze high-resolution observations from the 1.6 m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing, as observed in the Hα off-bands. The apparent speed of the flow is around 10–60 km s‑1 in the filament, decreasing to 5–20 km s‑1 in the light bridge. The most intriguing results are the magnetic structure and the counter-streaming motions in the light bridge. Similar to those in the filament, the magnetic fields show a dominant transverse component in the light bridge. However, the filament is located between opposed magnetic polarities, while the light bridge is between strong fields of the same polarity. We analyze the power of oscillations with the image sequences of constructed Dopplergrams, and find that the filament’s counter-streaming motion is due to physical mass motion along fibrils, while the light bridge’s counter-streaming motion is due to oscillation in the direction along the line-of-sight. The oscillation power peaks around 4 minutes. However, the section of the light bridge next to the filament also contains a component of the extension of the filament in combination with the oscillation, indicating that some strands of the filament are extended to and rooted in that part of the light bridge.

  2. Solar and wind exergy potentials for Mars

    International Nuclear Information System (INIS)

    Delgado-Bonal, Alfonso; Martín-Torres, F. Javier; Vázquez-Martín, Sandra; Zorzano, María-Paz

    2016-01-01

    The energy requirements of the planetary exploration spacecrafts constrain the lifetime of the missions, their mobility and capabilities, and the number of instruments onboard. They are limiting factors in planetary exploration. Several missions to the surface of Mars have proven the feasibility and success of solar panels as energy source. The analysis of the exergy efficiency of the solar radiation has been carried out successfully on Earth, however, to date, there is not an extensive research regarding the thermodynamic exergy efficiency of in-situ renewable energy sources on Mars. In this paper, we analyse the obtainable energy (exergy) from solar radiation under Martian conditions. For this analysis we have used the surface environmental variables on Mars measured in-situ by the Rover Environmental Monitoring Station onboard the Curiosity rover and from satellite by the Thermal Emission Spectrometer instrument onboard the Mars Global Surveyor satellite mission. We evaluate the exergy efficiency from solar radiation on a global spatial scale using orbital data for a Martian year; and in a one single location in Mars (the Gale crater) but with an appreciable temporal resolution (1 h). Also, we analyse the wind energy as an alternative source of energy for Mars exploration and compare the results with those obtained on Earth. We study the viability of solar and wind energy station for the future exploration of Mars, showing that a small square solar cell of 0.30 m length could maintain a meteorological station on Mars. We conclude that the low density of the atmosphere of Mars is responsible of the low thermal exergy efficiency of solar panels. It also makes the use of wind energy uneffective. Finally, we provide insights for the development of new solar cells on Mars. - Highlights: • We analyse the exergy of solar radiation under Martian environment • Real data from in-situ instruments is used to determine the maximum efficiency of radiation • Wind

  3. Solar wind velocity and geomagnetic moment variations

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Rozanova, T.S.

    1982-01-01

    The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

  4. Mirror Instability in the Turbulent Solar Wind

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Landi, S.; Matteini, L.; Verdini, A.; Franci, L.

    2017-01-01

    Roč. 838, č. 2 (2017), č. článku 158. ISSN 0004-637X Institutional support: RVO:68378289 Keywords : instabilities * solar wind * turbulence * waves Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 5.533, year: 2016 http://iopscience.iop.org/article/10.3847/1538-4357/aa67e0

  5. The Solar Wind as a Turbulence Laboratory

    Directory of Open Access Journals (Sweden)

    Bruno Roberto

    2005-09-01

    Full Text Available In this review we will focus on a topic of fundamental importance for both plasma physics and astrophysics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research field will be reported emphasizing the results obtained in the past decade or so. As a matter of fact, Ulysses’ high latitude observations and new numerical approaches to the problem, based on the dynamics of complex systems, brought new important insights which helped to better understand how turbulent fluctuations behave in the solar wind. In particular, numerical simulations within the realm of magnetohydrodynamic (MHD turbulence theory unraveled what kind of physical mechanisms are at the basis of turbulence generation and energy transfer across the spectral domain of the fluctuations. In other words, the advances reached in these past years in the investigation of solar wind turbulence now offer a rather complete picture of the phenomenological aspect of the problem to be tentatively presented in a rather organic way.

  6. Kinetic Properties of the Neutral Solar Wind

    International Nuclear Information System (INIS)

    Florinski, V.; Heerikhuisen, J.

    2017-01-01

    Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

  7. Kinetic Properties of the Neutral Solar Wind

    Science.gov (United States)

    Florinski, V.; Heerikhuisen, J.

    2017-03-01

    Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

  8. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  9. Counterstreaming-ion-tokamak fissile breeder

    International Nuclear Information System (INIS)

    Jassby, D.L.; Lee, J.D.

    1976-08-01

    Tokamak plasmas fueled and heated by energetic neutral-atom beams are characterized by total ion energy greatly exceeding the electron energy. For smaller devices the largest fusion reactivity of energetic-ion plasmas is obtained when oppositely injected D 0 and T 0 beams sustain counterstreaming velocity distributions of deuterons and tritons. This scoping study investigates the net fissile and power productions of a tokamak fusion-fission reactor with a counterstreaming-ion fusion driver and a fertile blanket optimized for fissile breeding. The fusion driver has parameters R/sub o/ = 4.7 m, a = 1.0 m, B/sub t/ = 5.6 T, W/sub b/ = 100 keV (D 0 ), n tau/sub E/ = 1.4 x 10 13 cm -3 s, Q = 1.5, 14-MeV neutron production = 175 MW. The blanket contains a fast-fission zone of natural U plus Mo (7 percent), followed by a Li-bearing zone for T breeding. The reactor produces a net power of 480 MWe and supplies sufficient Pu to support a system of LWR's producing 3800 MWe, with an estimated electrical energy cost for the entire system of 27 mills/kWh

  10. On the Origins of the Intercorrelations Between Solar Wind Variables

    Science.gov (United States)

    Borovsky, Joseph E.

    2018-01-01

    It is well known that the time variations of the diverse solar wind variables at 1 AU (e.g., solar wind speed, density, proton temperature, electron temperature, magnetic field strength, specific entropy, heavy-ion charge-state densities, and electron strahl intensity) are highly intercorrelated with each other. In correlation studies of the driving of the Earth's magnetosphere-ionosphere-thermosphere system by the solar wind, these solar wind intercorrelations make determining cause and effect very difficult. In this report analyses of solar wind spacecraft measurements and compressible-fluid computer simulations are used to study the origins of the solar wind intercorrelations. Two causes are found: (1) synchronized changes in the values of the solar wind variables as the plasma types of the solar wind are switched by solar rotation and (2) dynamic interactions (compressions and rarefactions) in the solar wind between the Sun and the Earth. These findings provide an incremental increase in the understanding of how the Sun-Earth system operates.

  11. ISOTOPIC MASS FRACTIONATION OF SOLAR WIND: EVIDENCE FROM FAST AND SLOW SOLAR WIND COLLECTED BY THE GENESIS MISSION

    International Nuclear Information System (INIS)

    Heber, Veronika S.; Baur, Heinrich; Wieler, Rainer; Bochsler, Peter; McKeegan, Kevin D.; Neugebauer, Marcia; Reisenfeld, Daniel B.; Wiens, Roger C.

    2012-01-01

    NASA's Genesis space mission returned samples of solar wind collected over ∼2.3 years. We present elemental and isotopic compositions of He, Ne, and Ar analyzed in diamond-like carbon targets from the slow and fast solar wind collectors to investigate isotopic fractionation processes during solar wind formation. The solar wind provides information on the isotopic composition for most volatile elements for the solar atmosphere, the bulk Sun and hence, on the solar nebula from which it formed 4.6 Ga ago. Our data reveal a heavy isotope depletion in the slow solar wind compared to the fast wind composition by 63.1 ± 2.1 per mille for He, 4.2 ± 0.5 per mille amu –1 for Ne and 2.6 ± 0.5 per mille amu –1 for Ar. The three Ne isotopes suggest that isotopic fractionation processes between fast and slow solar wind are mass dependent. The He/H ratios of the collected slow and fast solar wind samples are 0.0344 and 0.0406, respectively. The inefficient Coulomb drag model reproduces the measured isotopic fractionation between fast and slow wind. Therefore, we apply this model to infer the photospheric isotopic composition of He, Ne, and Ar from our solar wind data. We also compare the isotopic composition of oxygen and nitrogen measured in the solar wind with values of early solar system condensates, probably representing solar nebula composition. We interpret the differences between these samples as being due to isotopic fractionation during solar wind formation. For both elements, the magnitude and sign of the observed differences are in good agreement with the values predicted by the inefficient Coulomb drag model.

  12. ISOTOPIC MASS FRACTIONATION OF SOLAR WIND: EVIDENCE FROM FAST AND SLOW SOLAR WIND COLLECTED BY THE GENESIS MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Heber, Veronika S.; Baur, Heinrich; Wieler, Rainer [Institute for Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, CH-8092 Zurich (Switzerland); Bochsler, Peter [Physikalisches Institut, Universitaet Bern, Sidlerstasse 5, CH-3012 Bern (Switzerland); McKeegan, Kevin D. [Department of Earth and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095-1567 (United States); Neugebauer, Marcia [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092 (United States); Reisenfeld, Daniel B. [Department of Physics and Astronomy, University of Montana, Missoula, MT 59812 (United States); Wiens, Roger C., E-mail: heber@ess.ucla.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2012-11-10

    NASA's Genesis space mission returned samples of solar wind collected over {approx}2.3 years. We present elemental and isotopic compositions of He, Ne, and Ar analyzed in diamond-like carbon targets from the slow and fast solar wind collectors to investigate isotopic fractionation processes during solar wind formation. The solar wind provides information on the isotopic composition for most volatile elements for the solar atmosphere, the bulk Sun and hence, on the solar nebula from which it formed 4.6 Ga ago. Our data reveal a heavy isotope depletion in the slow solar wind compared to the fast wind composition by 63.1 {+-} 2.1 per mille for He, 4.2 {+-} 0.5 per mille amu{sup -1} for Ne and 2.6 {+-} 0.5 per mille amu{sup -1} for Ar. The three Ne isotopes suggest that isotopic fractionation processes between fast and slow solar wind are mass dependent. The He/H ratios of the collected slow and fast solar wind samples are 0.0344 and 0.0406, respectively. The inefficient Coulomb drag model reproduces the measured isotopic fractionation between fast and slow wind. Therefore, we apply this model to infer the photospheric isotopic composition of He, Ne, and Ar from our solar wind data. We also compare the isotopic composition of oxygen and nitrogen measured in the solar wind with values of early solar system condensates, probably representing solar nebula composition. We interpret the differences between these samples as being due to isotopic fractionation during solar wind formation. For both elements, the magnitude and sign of the observed differences are in good agreement with the values predicted by the inefficient Coulomb drag model.

  13. Turbulent Transport in a Three-dimensional Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Shiota, D. [Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Zank, G. P.; Adhikari, L.; Hunana, P. [Center for Space Plasma and Aeronomic Research (CSPAR), Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Telloni, D. [INAF—Astrophysical Observatory of Torino, Via Osservatorio 20, I-10025 Pino Torinese (Italy); Bruno, R., E-mail: shiota@isee.nagoya-u.ac.jp [INAF-IAPS Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy)

    2017-03-01

    Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for the temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.

  14. Solar wind acceleration in coronal holes

    International Nuclear Information System (INIS)

    Kopp, R.A.

    1978-01-01

    Past attempts to explain the large solar wind velocities in high speed streams by theoretical models of the expansion have invoked either extended nonthermal heating of the corona, heat flux inhibition, or direct addition of momentum to the expanding coronal plasma. Several workers have shown that inhibiting the heat flux at low coronal densities is probably not adequate to explain quantitatively the observed plasma velocities in high speed streams. It stressed that, in order to account for both these large plasma velocities and the low densities found in coronal holes (from which most high speed streams are believed to emanate), extended heating by itself will not suffice. One needs a nonthermal mechanism to provide the bulk acceleration of the high wind plasma close to the sun, and the most likely candidate at present is direct addition of the momentum carried by outward-propagating waves to the expanding corona. Some form of momentum addition appears to be absolutely necessary if one hopes to build quantitatively self-consistent models of coronal holes and high speed solar wind streams

  15. Morphology of Pseudostreamers and Solar Wind Properties

    Science.gov (United States)

    Panasenco, Olga; Velli, Marco

    2016-05-01

    The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop the specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers (PSs) if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of PSs shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at the PS base low in the corona.

  16. First Results from ARTEMIS, A New Two-Spacecraft Lunar Mission: Counter-Streaming Plasma Populations in the Lunar Wake

    Science.gov (United States)

    Halekas, J. S.; Angelopoulos, V.; Sibeck, D. G.; Khurana, K. K.; Russell, C. T.; Delory, G. T.; Farrell, W. M.; McFadden, J. P.; Bonnell, J. W.; Larson, D.; hide

    2014-01-01

    We present observations from the first passage through the lunar plasma wake by one of two spacecraft comprising ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun), a new lunar mission that re-tasks two of five probes from the THEMIS magnetospheric mission. On Feb 13, 2010, ARTEMIS probe P1 passed through the wake at approximately 3.5 lunar radii downstream from the Moon, in a region between those explored by Wind and the Lunar Prospector, Kaguya, Chandrayaan, and Chang'E missions. ARTEMIS observed interpenetrating proton, alpha particle, and electron populations refilling the wake along magnetic field lines from both flanks. The characteristics of these distributions match expectations from self-similar models of plasma expansion into vacuum, with an asymmetric character likely driven by a combination of a tilted interplanetary magnetic field and an anisotropic incident solar wind electron population. On this flyby, ARTEMIS provided unprecedented measurements of the interpenetrating beams of both electrons and ions naturally produced by the filtration and acceleration effects of electric fields set up during the refilling process. ARTEMIS also measured electrostatic oscillations closely correlated with counter-streaming electron beams in the wake, as previously hypothesized but never before directly measured. These observations demonstrate the capability of the comprehensively instrumented ARTEMIS spacecraft and the potential for new lunar science from this unique two spacecraft constellation.

  17. The sun, the solar wind, and the heliosphere

    CERN Document Server

    Miralles, Mari Paz

    2011-01-01

    This volume presents a concise, up-to-date overview of current research on the observations, theoretical interpretations, and empirical and physical descriptions of the Sun, the Solar Wind, and the Heliosphere, from the solar interior outward to the planets.

  18. Coulomb collisions in the solar wind

    Science.gov (United States)

    Klein, L. W.; Ogilvie, K. W.; Burlaga, L. F.

    1985-01-01

    A major improvement of the present investigation over previous studies of the subject is related to the use of helium temperatures obtained from helium ion measurements uncontaminated by the high-velocity tail of the proton distribution. More observations, covering a large parameter range, were employed, and the effects of interspecies drift were taken into account. It is shown in a more definite way than has been done previously, that Coulomb collisions provide the most important mechanism bringing about equilibrium between helium and protons in the solar wind. Other mechanisms may play some part in restricted regions, but Coulomb collisions are dominant on the macroscale.

  19. Simulation experiments and solar wind sputtering

    International Nuclear Information System (INIS)

    Griffith, J.E.; Papanastassiou, D.A.; Russell, W.A.; Tombrello, T.A.; Weller, R.A.

    1978-01-01

    In order to isolate the role played by solar wind sputtering from other lunar surface phenomena a number of simulation experiments were performed, including isotope abundance measurements of Ca sputtered from terrestrial fluorite and plagioclase by 50-keV and 130-keV 14 N beams, measurement of the energy distribution of U atoms sputtered with 80-keV 40 Ar, and measurement of the fraction of sputtered U atoms which stick on the surfaces used to collect these atoms. 10 references

  20. Genesis Solar Wind Science Canister Components Curated as Potential Solar Wind Collectors and Reference Contamination Sources

    Science.gov (United States)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2016-01-01

    The Genesis mission collected solar wind for 27 months at Earth-Sun L1 on both passive and active collectors carried inside of a Science Canister, which was cleaned and assembled in an ISO Class 4 cleanroom prior to launch. The primary passive collectors, 271 individual hexagons and 30 half-hexagons of semiconductor materials, are described in. Since the hard landing reduced the 301 passive collectors to many thousand smaller fragments, characterization and posting in the online catalog remains a work in progress, with about 19% of the total area characterized to date. Other passive collectors, surfaces of opportunity, have been added to the online catalog. For species needing to be concentrated for precise measurement (e.g. oxygen and nitrogen isotopes) an energy-independent parabolic ion mirror focused ions onto a 6.2 cm diameter target. The target materials, as recovered after landing, are described in. The online catalog of these solar wind collectors, a work in progress, can be found at: http://curator.jsc.nasa.gov/gencatalog/index.cfm This paper describes the next step, the cataloging of pieces of the Science Canister, which were surfaces exposed to the solar wind or component materials adjacent to solar wind collectors which may have contributed contamination.

  1. The solar wind and the earth

    International Nuclear Information System (INIS)

    Akasofu, I.; Kamide, Y.

    1987-01-01

    The sun constantly emits an enormous amount of radiation into space. This energy emission consists of three modes. Almost all the energy is emitted in the form of familiar sunlight but sun also emits X-rays, extreme ultraviolet (EUV), and UV radiation, which is absorbed above the earth's stratosphere, as a second mode of solar energy. The sun has made another important mode of energy emission in which the energy is carried out by charged particles. These particles have a bery wide range of energies, from less than 1 keV to more than 1 GeV. Because of this wide range, it is convenient to group them into two components: particles, with energies greater than 10 keV and the lower-energy particles. The former are generally referred to as solar portions or solar cosmic rays; their emission is associated with active features on the sun. Low-energy particles constitute plasma which is called the solar wind

  2. The 3-D solar radioastronomy and the structure of the corona and the solar wind. [solar probes of solar activity

    Science.gov (United States)

    Steinberg, J. L.; Caroubalos, C.

    1976-01-01

    The mechanism causing solar radio bursts (1 and 111) is examined. It is proposed that a nonthermal energy source is responsible for the bursts; nonthermal energy is converted into electromagnetic energy. The advantages are examined for an out-of-the-ecliptic solar probe mission, which is proposed as a means of stereoscopically viewing solar radio bursts, solar magnetic fields, coronal structure, and the solar wind.

  3. Solar wind structure out of the ecliptic plane over solar cycles

    Science.gov (United States)

    Sokol, J. M.; Bzowski, M.; Tokumaru, M.

    2017-12-01

    Sun constantly emits a stream of plasma known as solar wind. Ground-based observations of the solar wind speed through the interplanetary scintillations (IPS) of radio flux from distant point sources and in-situ measurements by Ulysses mission revealed that the solar wind flow has different characteristics depending on the latitude. This latitudinal structure evolves with the cycle of solar activity. The knowledge on the evolution of solar wind structure is important for understanding the interaction between the interstellar medium surrounding the Sun and the solar wind, which is responsible for creation of the heliosphere. The solar wind structure must be taken into account in interpretation of most of the observations of heliospheric energetic neutral atoms, interstellar neutral atoms, pickup ions, and heliospheric backscatter glow. The information on the solar wind structure is not any longer available from direct measurements after the termination of Ulysses mission and the only source of the solar wind out of the ecliptic plane is the IPS observations. However, the solar wind structure obtained from this method contains inevitable gaps in the time- and heliolatitude coverage. Sokół et al 2015 used the solar wind speed data out of the ecliptic plane retrieved from the IPS observations performed by Institute for Space-Earth Environmental Research (Nagoya University, Japan) and developed a methodology to construct a model of evolution of solar wind speed and density from 1985 to 2013 that fills the data gaps. In this paper we will present a refined model of the solar wind speed and density structure as a function of heliographic latitude updated by the most recent data from IPS observations. And we will discuss methods of extrapolation of the solar wind structure out of the ecliptic plane for the past solar cycles, when the data were not available, as well as forecasting for few years upward.

  4. Solar wind velocity and temperature in the outer heliosphere

    Science.gov (United States)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1994-01-01

    At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum.

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

    Directory of Open Access Journals (Sweden)

    Keunchan Park

    2017-06-01

    Full Text Available Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE and the Wind satellite. We also calculate two pressures (magnetic, dynamic and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME. We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

  6. The solar wind in the third dimension

    International Nuclear Information System (INIS)

    Neugebauer, M.

    1996-01-01

    For many years, solar-wind physicists have been using plasma and field data acquired near the ecliptic plane together with data on the scintillation of radio sources and remote sensing of structures in the solar corona to estimate the properties of the high-latitude solar wind. Because of the highly successful Ulysses mission, the moment of truth is now here. This paper summarizes the principal agreements and differences between the Ulysses observations and expectations. The speed of the high-latitude solar wind was even greater than anticipated. The strength of the radial component of the interplanetary magnetic field was found to be independent of latitude. The tilt of the heliospheric current sheet caused reverse corotating shocks to be observed to higher latitudes than forward corotating shocks. The energetic particles accelerated in these shocks were detected well poleward of the latitudes at which Ulysses observed the interaction regions themselves. As anticipated, there was a strong flux of outward propagating Alfven waves throughout the polar flow. Those waves were probably largely responsible for the smaller-than-anticipated increase of galactic cosmic rays with increasing latitude. As expected, the charge state or ionization temperature of heavy ions was lower in the polar flow than in low-latitude interstream flows. What was not anticipated was the correlation of elemental abundances with ionization temperatures; the Ulysses data revealed a connection between the first ionization time in the upper chromosphere and the final ionization state in the corona. As expected, transient events were detected to ∼60 deg. latitude, but the properties of those high latitude transient flows held some surprises. At high latitudes, the speeds of the transient interplanetary plasma clouds were approximately the same as the speed of the ambient plasma and the expansion of the clouds drove forward and reverse shock pairs that had never been seen at low latitudes. At high

  7. Were chondrites magnetized by the early solar wind?

    Science.gov (United States)

    Oran, Rona; Weiss, Benjamin P.; Cohen, Ofer

    2018-06-01

    Chondritic meteorites have been traditionally thought to be samples of undifferentiated bodies that never experienced large-scale melting. This view has been challenged by the existence of post-accretional, unidirectional natural remanent magnetization (NRM) in CV carbonaceous chondrites. The relatively young inferred NRM age [∼10 million years (My) after solar system formation] and long duration of NRM acquisition (1-106 y) have been interpreted as evidence that the magnetizing field was that of a core dynamo within the CV parent body. This would imply that CV chondrites represent the primitive crust of a partially differentiated body. However, an alternative hypothesis is that the NRM was imparted by the early solar wind. Here we demonstrate that the solar wind scenario is unlikely due to three main factors: 1) the magnitude of the early solar wind magnetic field is estimated to be limits field amplification due to pile-up of the solar wind to less than a factor of 3.5 times that of the instantaneous solar wind field, and 3) the solar wind field likely changed over timescales orders of magnitude shorter than the timescale of NRM acquisition. Using analytical arguments, numerical simulations and astronomical observations of the present-day solar wind and magnetic fields of young stars, we show that the maximum mean field the ancient solar wind could have imparted on an undifferentiated CV parent body is <3.5 nT, which is 3-4 and 3 orders of magnitude weaker than the paleointensities recorded by the CV chondrites Allende and Kaba, respectively. Therefore, the solar wind is highly unlikely to be the source of the NRM in CV chondrites. Nevertheless, future high sensitivity paleomagnetic studies of rapidly-cooled meteorites with high magnetic recording fidelity could potentially trace the evolution of the solar wind field in time.

  8. Solar Wind Associated with Near Equatorial Coronal Hole M ...

    Indian Academy of Sciences (India)

    2015-05-25

    May 25, 2015 ... coronal hole and solar wind. For both the wavelength bands, we also com- pute coronal hole radiative energy near the earth and it is found to be of similar order as that of solar wind energy. However, for the wavelength. 193 Å, owing to almost similar magnitudes of energy emitted by coronal hole and ...

  9. Alfvénic fluctuations in "newborn"' polar solar wind

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2005-06-01

    Full Text Available The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind – Space plasma physics (Turbulence

  10. The Western Wind and Solar Integration Study Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Lew, Debra [National Renewable Energy Lab. (NREL), Golden, CO (United States); Brinkman, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ibanez, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Florita, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Heaney, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hodge, B. -M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hummon, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stark, G. [National Renewable Energy Lab. (NREL), Golden, CO (United States); King, J. [RePPAE; Lefton, S. A. [Intertek-APTECH, Houston, TX (United States); Kumar, N. [Intertek-APTECH, Houston, TX (United States); Agan, D. [Intertek-APTECH, Houston, TX (United States); Jordan, G. [GE Energy, Fairfield, CT (United States); Venkataraman, S. [GE Energy, Fairfield, CT (United States)

    2013-09-01

    The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West(GE Energy 2010).

  11. The Western Wind and Solar Integration Study Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Lew, D.; Brinkman, G.; Ibanez, E.; Hodge, B. M.; Hummon, M.; Florita, A.; Heaney, M.

    2013-09-01

    The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) evaluated these costs and emissions and simulated grid operations for a year to investigate the detailed impact of wind and solar on the fossil-fueled fleet. This built on Phase 1, one of the largest wind and solar integration studies ever conducted, which examined operational impacts of high wind and solar penetrations in the West.

  12. The model of unshocked deceleration of the solar wind

    International Nuclear Information System (INIS)

    Gidalevich, E.Ya.

    1977-01-01

    The motion of the Sun relative to the interstellar gas is considered as an hydrodynamic flow in a point-source field. Interstellar gas has been found to undergo considerable compaction as it is braked in the solar gravitational field. Solar-wind braking due to ion charge exchange processes on interstellar hydrogen atoms is discussed. It is shown that tangible solar-wind braking occurs at a distance of about 3x1O 14 cm from the Sun in the apex direction. In the opposite direction solar wind propagates freely

  13. Innovations in Wind and Solar PV Financing

    Energy Technology Data Exchange (ETDEWEB)

    Cory, K.; Coughlin, J.; Jenkin, T.; Pater, J.; Swezey, B.

    2008-02-01

    There is growing national interest in renewable energy development based on the economic, environmental, and security benefits that these resources provide. Historically, greater development of our domestic renewable energy resources has faced a number of hurdles, primarily related to cost, regulation, and financing. With the recent sustained increase in the costs and associated volatility of fossil fuels, the economics of renewable energy technologies have become increasingly attractive to investors, both large and small. As a result, new entrants are investing in renewable energy and new business models are emerging. This study surveys some of the current issues related to wind and solar photovoltaic (PV) energy project financing in the electric power industry, and identifies both barriers to and opportunities for increased investment.

  14. Suprathermal protons in the interplanetary solar wind

    Science.gov (United States)

    Goodrich, C. C.; Lazarus, A. J.

    1976-01-01

    Using the Mariner 5 solar wind plasma and magnetic field data, we present observations of field-aligned suprathermal proton velocity distributions having pronounced high-energy shoulders. These observations, similar to the interpenetrating stream observations of Feldman et al. (1974), are clear evidence that such proton distributions are interplanetary rather than bow shock associated phenomena. Large Alfven speed is found to be a requirement for the occurrence of suprathermal proton distribution; further, we find the proportion of particles in the shoulder to be limited by the magnitude of the Alfven speed. It is suggested that this last result could indicate that the proton thermal anisotropy is limited at times by wave-particle interactions

  15. Dst Prediction Based on Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Yoon-Kyung Park

    2009-12-01

    Full Text Available We reevaluate the Burton equation (Burton et al. 1975 of predicting Dst index using high quality hourly solar wind data supplied by the ACE satellite for the period from 1998 to 2006. Sixty magnetic storms with monotonously decreasing main phase are selected. In order to determine the injection term (Q and the decay time (tau of the equation, we examine the relationships between Dst* and VB_s, Delta Dst* and VB_s, and Delta Dst* and Dst* during the magnetic storms. For this analysis, we take into account one hour of the propagation time from the ACE satellite to the magnetopause, and a half hour of the response time of the magnetosphere/ring current to the solar wind forcing. The injection term is found to be Q({nT}/h=-3.56VB_s for VB_s>0.5mV/m and Q({nT}/h=0 for VB_s leq0.5mV/m. The tau (hour is estimated as 0.060 Dst* + 16.65 for Dst*>-175nT and 6.15 hours for Dst* leq -175nT. Based on these empirical relationships, we predict the 60 magnetic storms and find that the correlation coefficient between the observed and predicted Dst* is 0.88. To evaluate the performance of our prediction scheme, the 60 magnetic storms are predicted again using the models by Burton et al. (1975 and O'Brien & McPherron (2000a. The correlation coefficients thus obtained are 0.85, the same value for both of the two models. In this respect, our model is slightly improved over the other two models as far as the correlation coefficients is concerned. Particularly our model does a better job than the other two models in predicting intense magnetic storms (Dst* lesssim -200nT.

  16. Extended neutral atmosphere effect on solar wind interaction with nonmagnetic bodies of the solar system

    International Nuclear Information System (INIS)

    Breus, T.K.; Krymskij, A.M.; Mitnitskij, V.Ya.

    1987-01-01

    Numeric modelling of the Venus flow-around by the solar wind with regard to stream loading by heavy ions, produced under photoionization of the Venus neutral oxygen corona, is conducted. It is shown, that this effect can account for a whole number of peculiarities related to the solar wind interaction with the planet which have not been clearly explained yet, namely, shock wave position, solar wind stream and magnetic field characteristics behind the front

  17. Wind tunnel and CFD modelling of wind pressures on solar energy systems on flat roofs

    NARCIS (Netherlands)

    Bronkhorst, A.J.; Franke, J.; Geurts, C.P.W.; Bentum, van C.A.; Grepinet, F.

    2010-01-01

    Design of solar energy mounting systems requires more knowledge on the wind patterns around these systems. To obtain more insight in the flow patterns, which cause the pressure distributions on the solar energy systems, a wind tunnel test and Computational Fluid Dynamics analysis have been

  18. Electrifying Greece with solar and wind energy

    Directory of Open Access Journals (Sweden)

    Mentis Dimitris

    2014-01-01

    Full Text Available Ensuring energy security, reducing GHG emissions and boosting the competitiveness of a country’s economy by attracting investments and technical knowhow are of paramount importance considering the targets of “20-20-20” set by the European community. Being the cradle of civilization, Greece appears today as a country caught in a prolonged hard economic and social crisis, the way out of which its citizens are looking forward as well as the entire European Union. Establishment of the leading renewable energy sources like solar and wind in Greece will not only increase the independence of its own electrification but will also provide with a foundation for developing the market of international trade of “green” energy. This paper initially highlights the current status of photovoltaics and wind turbines in Greece. Furthermore, this study evaluates whether a higher penetration of the above mentioned green energy sources would have positive impact in the economy of the country or not and in what extent they could decline the CO2 emissions until 2020, comparing to the corresponding levels in 2010.

  19. CONDITIONED ANALYSIS OF HIGH-LATITUDE SOLAR WIND INTERMITTENCY

    International Nuclear Information System (INIS)

    D'Amicis, R.; Consolini, G.; Bavassano, B.; Bruno, R.

    2012-01-01

    The solar wind is a turbulent medium displaying intermittency. Its intermittent features have been widely documented and studied, showing how the intermittent character is different in fast and slow wind. In this paper, a statistical conditioned analysis of the solar wind intermittency for a period of high-latitude fast solar wind is presented. In particular, the intermittent features are investigated as a function of the Alfvénic degree of fluctuations at a given scale. The results show that the main contribution to solar wind intermittency is due to non-Alfvénic structures, while Alfvénic increments are found to be characterized by a smaller level of intermittency than the previous ones. Furthermore, the lifetime statistics of Alfvénic periods are discussed in terms of a multiscale texture of randomly oriented flux tubes.

  20. Charge States of Krypton and Xenon in the Solar Wind

    Science.gov (United States)

    Bochsler, Peter; Fludra, Andrzej; Giunta, Alessandra

    2017-09-01

    We calculate charge state distributions of Kr and Xe in a model for two different types of solar wind using the effective ionization and recombination rates provided from the OPEN_ADAS data base. The charge states of heavy elements in the solar wind are essential for estimating the efficiency of Coulomb drag in the inner corona. We find that xenon ions experience particularly low Coulomb drag from protons in the inner corona, comparable to the notoriously weak drag of protons on helium ions. It has been found long ago that helium in the solar wind can be strongly depleted near interplanetary current sheets, whereas coronal mass ejecta are sometimes strongly enriched in helium. We argue that if the extraordinary variability of the helium abundance in the solar wind is due to inefficient Coulomb drag, the xenon abundance must vary strongly. In fact, a secular decrease of the solar wind xenon abundance relative to the other heavier noble gases (Ne, Ar, Kr) has been postulated based on a comparison of noble gases in recently irradiated and ancient samples of ilmenite in the lunar regolith. We conclude that decreasing solar activity and decreasing frequency of coronal mass ejections over the solar lifetime might be responsible for a secularly decreasing abundance of xenon in the solar wind.

  1. Weather-power station. Solar energy, wind energy, water energy

    Energy Technology Data Exchange (ETDEWEB)

    Schatta, M

    1975-10-02

    A combined power station is described, which enables one to convert solar energy and wind energy into other forms of energy. The plant consists of a water-filled boiler, in which solar energy heats the water by concentration, solar cells, and finally wind rotors, which transform wind energy into electrical energy. The transformed energy is partly available as steam heat, partly as mechanical or electrical energy. The plant can be used for supplying heating systems or electrolysis equipment. Finally, by incorporating suitable motors, a mobile version of the system can be produced.

  2. Wind and Solar Curtailment: International Experience and Practices

    DEFF Research Database (Denmark)

    Lew, Debra; Bird, Lori; Milligan, Michael

    2013-01-01

    High penetrations of wind and solar generation on power systems are resulting in increasing curtailment. Wind and solar integration studies predict increased curtailment as penetration levels grow. This paper examines experiences with curtailment on bulk power systems internationally. It discusses...... how much curtailment is occurring, how it is occurring, why it is occurring, and what is being done to reduce curtailment. This summary is produced as part of the International Energy Agency Wind Task 25 on Design and Operation of Power Systems with Large Amounts of Wind Power....

  3. Different magnetospheric modes: solar wind driving and coupling efficiency

    Directory of Open Access Journals (Sweden)

    N. Partamies

    2009-11-01

    Full Text Available This study describes a systematic statistical comparison of isolated non-storm substorms, steady magnetospheric convection (SMC intervals and sawtooth events. The number of events is approximately the same in each group and the data are taken from about the same years to avoid biasing by different solar cycle phase. The very same superposed epoch analysis is performed for each event group to show the characteristics of ground-based indices (AL, PCN, PC potential, particle injection at the geostationary orbit and the solar wind and IMF parameters. We show that the monthly occurrence of sawtooth events and isolated non-stormtime substorms closely follows maxima of the geomagnetic activity at (or close to the equinoxes. The most strongly solar wind driven event type, sawtooth events, is the least efficient in coupling the solar wind energy to the auroral ionosphere, while SMC periods are associated with the highest coupling ratio (AL/EY. Furthermore, solar wind speed seems to play a key role in determining the type of activity in the magnetosphere. Slow solar wind is capable of maintaining steady convection. During fast solar wind streams the magnetosphere responds with loading–unloading cycles, represented by substorms during moderately active conditions and sawtooth events (or other storm-time activations during geomagnetically active conditions.

  4. Transient flows of the solar wind associated with small-scale solar activity in solar minimum

    Science.gov (United States)

    Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid

    The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme

  5. Small Footprint Solar/Wind-powered CASTNET System Dataset

    Data.gov (United States)

    U.S. Environmental Protection Agency — In this Research Effort “Small Footprint Solar/Wind-Powered CASTNET System” there are two data sets. One data set contains atmospheric concentration measurements, at...

  6. Saturn radio emission and the solar wind - Voyager-2 studies

    International Nuclear Information System (INIS)

    Desch, M.D.; Rucker, H.O.; Observatorium Lustbuhel, Graz, Austria)

    1985-01-01

    Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the relationship between parameters of the solar wind/interplanetary medium and the nonthermal Saturn radiation. Solar wind and interplanetary magnetic field properties were combined to form quantities known to be important in controlling terrestrial magnetospheric processes. The Voyager 2 data set used in this investigation consists of 237 days of Saturn preencounter measurements. However, due to the immersion of Saturn and the Voyager 2 spacecraft into the extended Jupiter magnetic tail, substantial periods of the time series were lacking solar wind data. To cope with this problem a superposed epoch method (CHREE analysis) was used. The results indicate the superiority of the quantities containing the solar wind density in stimulating the radio emission of Saturn - a result found earlier using Voyager 1 data - and the minor importance of quantities incorporating the interplanetary magnetic field. 10 references

  7. Western Wind and Solar Integration Study: Phase 2 (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Lew, D.; Brinkman, G.; Ibanez, E.; Lefton, S.; Kumar, N.; Venkataraman, S.; Jordan, G.

    2013-09-01

    This presentation summarizes the scope and results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

  8. Analysis of ISEE-3/ICE solar wind data

    Science.gov (United States)

    Coplan, Michael A.

    1989-01-01

    Under the grant that ended November 11, 1988 work was accomplished in a number of areas, as follows: (1) Analysis of solar wind data; (2) Analysis of Giacobini/Zinner encounter data; (3) Investigation of solar wind and magnetospheric electron velocity distributions; and (4) Experimental investigation of the electronic structure of clusters. Reprints and preprints of publications resulting from this work are included in the appendices.

  9. Electron heat flux instabilities in the solar wind

    International Nuclear Information System (INIS)

    Gary, S.P.; Feldman, W.C.; Forslund, D.W.; Montgomery, M.D.

    1975-01-01

    There are at least three plasma instabilities associated with the electron heat flux in the solar wind. This letter reports the study of the unstable fast magnetosonic, Alfven and whistler modes via a computer code which solves the full electromagnetic, linear, Vlasov dispersion relation. Linear theory demonstrates that both the magnetosonic and Alfven instabilities are candidates for turbulent limitation of the heat flux in the solar wind at 1 A.U

  10. Economic viability of wind and solar energy for industrial use

    International Nuclear Information System (INIS)

    Lashkari, Z.F.

    1994-01-01

    Non conventional energy sources have begun to move from fringes of technological possibility towards commercial viability. Out of the four sources, i e. solar, wind, biogas and minimicro hydel the first two viz. wind and solar energy are of relevance for industries in western region of India. This has to be seen in the context of developments in technology and hence economics both worldwide and in India. (author)

  11. On Electron-Scale Whistler Turbulence in the Solar Wind

    Science.gov (United States)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Giles, B.; Magnes, W.; Fischer, D.; Torbert, R. B.; Russell, C. T.

    2016-01-01

    For the first time, the dispersion relation for turbulence magnetic field fluctuations in the solar wind is determined directly on small scales of the order of the electron inertial length, using four-point magnetometer observations from the Magnetospheric Multiscale mission. The data are analyzed using the high-resolution adaptive wave telescope technique. Small-scale solar wind turbulence is primarily composed of highly obliquely propagating waves, with dispersion consistent with that of the whistler mode.

  12. Potential for Development of Solar and Wind Resource in Bhutan

    Energy Technology Data Exchange (ETDEWEB)

    Gilman, P.; Cowlin, S.; Heimiller, D.

    2009-09-01

    With support from the U.S. Agency for International Development (USAID), the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) produced maps and data of the wind and solar resources in Bhutan. The solar resource data show that Bhutan has an adequate resource for flat-plate collectors, with annual average values of global horizontal solar radiation ranging from 4.0 to 5.5 kWh/m2-day (4.0 to 5.5 peak sun hours per day). The information provided in this report may be of use to energy planners in Bhutan involved in developing energy policy or planning wind and solar projects, and to energy analysts around the world interested in gaining an understanding of Bhutan's wind and solar energy potential.

  13. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  14. Diamagnetic effect in the foremoon solar wind observed by Kaguya

    Science.gov (United States)

    Nishino, Masaki N.; Saito, Yoshifumi; Tsunakawa, Hideo; Miyake, Yohei; Harada, Yuki; Yokota, Shoichiro; Takahashi, Futoshi; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi

    2017-04-01

    Direct interaction between the lunar surface and incident solar wind is one of the crucial phenomena of the planetary plasma sciences. Recent observations by lunar orbiters revealed that strength of the interplanetary magnetic field (IMF) at spacecraft altitude often increases over crustal magnetic fields on the dayside. In addition, variations of the IMF on the lunar night side have been reported in the viewpoint of diamagnetic effect around the lunar wake. However, few studies have been performed for the IMF over non-magnetized regions on the dayside. Here we show an event where strength of the IMF decreases at 100 km altitude on the lunar dayside (i.e. in the foremoon solar wind) when the IMF is almost parallel to the incident solar wind flow, comparing the upstream solar wind data from ACE with Kaguya magnetometer data. The lunar surface below the Kaguya orbit is not magnetized (or very weakly magnetized), and the sunward-travelling protons show signatures of those back-scattered at the lunar surface. We find that the decrease in the magnetic pressure is compensated by the thermal pressure of the back-scattered protons. In other words, the IMF strength in the foremoon solar wind decreases by diamagnetic effect of sunward-travelling protons back-scattered at the lunar dayside surface. Such an effect would be prominent in the high-beta solar wind, and may be ubiquitous in the environment where planetary surface directly interacts with surrounding space plasma.

  15. Implications of the Deep Minimum for Slow Solar Wind Origin

    Science.gov (United States)

    Antiochos, S. K.; Mikic, Z.; Lionello, R.; Titov, V. S.; Linker, J. A.

    2009-12-01

    The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric current sheet. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of the Deep Minimum, affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at the Deep Minimum and describe further observational and theoretical tests. This work has been supported by the NASA HTP, SR&T, and LWS programs.

  16. Solar wind temperature observations in the outer heliosphere

    Science.gov (United States)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1992-01-01

    The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now at heliocentric distances of 50, 32 and 33 AU, and heliographic latitudes of 3.5 deg N, 17 deg N, and 0 deg N, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer l0 is on the opposite side of the sun. The baselines defined by these spacecraft make it possible to resolve radial, longitudinal, and latitudinal variations of solar wind parameters. The solar wind temperature decreases with increasing heliocentric distance out to a distance of 10-15 AU. At larger heliocentric distances, this gradient disappears. These high solar wind temperatures in the outer heliosphere have persisted for at least 10 years, which suggests that they are not a solar cycle effect. The solar wind temperature varied with heliographic latitude during the most recent solar minimum. The solar wind temperature at Pioneer 11 and Voyager 2 was higher than that seen at Pioneer 10 for an extended period of time, which suggests the existence of a large-scale variation of temperature with celestial longitude, but the contribution of transient phenomena is yet to be clarified.

  17. Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

    Directory of Open Access Journals (Sweden)

    A. B. Galvin

    2009-10-01

    Full Text Available STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007 which includes minor ion (He, Fe, O kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

  18. The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations

    Directory of Open Access Journals (Sweden)

    A. R. Breen

    Full Text Available The solar maximum solar wind is highly structured in latitude, longitude and in time. Coronal measurements show a very high degree of variability, with large variations that are less apparent within in situ spacecraft measurements. Interplanetary scintillation (IPS observations from EISCAT, covering distances from 20 to 100 solar radii (RS, are an ideal source of information on the inner solar wind and can be used, therefore, to cast light on its evolution with distance from the Sun. Earlier comparisons of in situ and IPS measurements under solar minimum conditions showed good large-scale agreement, particularly in the fast wind. In this study we attempt a quantitative comparison of measurements made over solar maximum by EISCAT (20–100 RS and the Wind and Ulysses spacecraft (at 215 RS and 300–1000 RS, respectively. The intervals studied were August–September 1999, May 2000, September 2000 and May 2001, the last-named being the period of the second Ulysses fast latitude scan. Both ballistic and – when possible – MHD/ballistic hybrid models were used to relate the data sets, and we compare the results obtained from these two mapping methods. The results of this study suggest that solar wind velocities measured in situ were less variable than those estimated from IPS measurements closer to the Sun, with the greatest divergence between IPS velocities and in situ measurements occurring in regions where steep longitudinal velocity gradients were seen in situ. We suggest that the interaction between streams of solar wind with different velocities leads to "smoothing" of solar wind velocities between 30–60 RS and 1 AU, and that this process continues at greater distances from the Sun.

    Key words. Interplanetary physics (solar wind plasma; sources of the solar wind; instruments and techniques

  19. A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Directory of Open Access Journals (Sweden)

    Robert Wilkes Ebert

    2014-09-01

    Full Text Available We examine Ulysses solar wind and interplanetary magnetic field (IMF observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 – 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013, Jupiter’s bow shock and magnetopause is expected to be at least 8 – 12% further from Jupiter, if these trends continue.

  20. A survey of solar wind conditions at 5 AU: a tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, Robert W. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Bagenal, Fran [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States); McComas, David J. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX (United States); Fowler, Christopher M., E-mail: rebert@swri.edu [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States)

    2014-09-19

    We examine Ulysses solar wind and interplanetary magnetic field (IMF) observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1–4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013a), Jupiter's bow shock and magnetopause is expected to be at least 8–12% further from Jupiter, if these trends continue.

  1. Multicriteria GIS modeling of wind and solar farms in Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Jason R. [Metropolitan State College of Denver, Department of Earth and Atmospheric Sciences, CB 22 P.O. Box 173362-22, Denver, CO 80217-3362 (United States)

    2010-10-15

    The majority of electricity and heat in Colorado comes from coal and natural gas; however, renewable energy sources will play an integral role in the state's energy future. Colorado is the 11th windiest state and has more than 250 sunny days per year. The objectives of this research are to: 1) determine which landcover classes are affiliated with high wind and solar potential; and 2) identify areas that are suitable for wind and solar farms using multicriteria GIS modelling techniques. Renewable potential (NREL wind speed measurements at 50 m above the ground and NREL annual insolation data), landcover, population density, federal lands, and distance to roads, transmission lines, and cities were reclassified according to their suitability. Each was assigned weights based on their relative importance to one another. Superb wind classes are located in high alpine areas. Unfortunately, these areas are not suitable for large-scale wind farm development due to their inaccessibility and location within a sensitive ecosystem. Federal lands have low wind potential. According to the GIS model, ideal areas for wind farm development are located in northeastern Colorado. About 41 850 km{sup 2} of the state has model scores that are in the 90-100% range. Although annual solar radiation varies slightly, inter-mountain areas receive the most insolation. As far as federal lands, Indian reservations have the greatest solar input. The GIS model indicates that ideal areas for solar development are located in northwestern Colorado and east of Denver. Only 191 km{sup 2} of the state had model scores that were in the 90-100% range. These results suggest that the variables used in this analysis have more of an effect at eliminating non-suitable areas for large-scale solar farms; a greater area exists for suitable wind farms. However, given the statewide high insolation values with minimal variance, solar projects may be better suited for small-scale residential or commercial

  2. Observation of solar wind with radio-star scintillation

    International Nuclear Information System (INIS)

    Watanabe, Takashi

    1974-01-01

    Large solar flares occurred in groups in early August 1972, and many interesting phenomena were observed. The solar wind condition during this period, obtained by scintillation observation, is reviewed. The velocity of solar wind has been determined from the observation of interplanetary space scintillation at Toyokawa, Fujigamine and Sugadaira. Four to ten radio wave sources were observed for ten minutes at each southing every day. Strong earth magnetic storm and the Forbush decrease of cosmic ray were observed during the period from August 3rd to 7th. Pioneer 9 observed a solar wind having the maximum velocity as high as 1,100 km/sec, and HEOS-II observed a solar wind having the velocity close to 2,000 km/sec. On the other hand, according to the scintillation of 3C-48 and 3C-144, the velocity of solar wind passing in the interplanetary space on the westside of the earth was only 300 to 400 km/sec. Therefore it is considered that the condition of solar wind on the east side of the earth differs from that on the west side of the earth. Pioneer 9 observed the pass of a shock wave on August 9th. With all radio wave sources, high velocity solar wind was observed and Pioneer 6 positioned on the west side of the earth also observed it. The thickness of this shock wave is at least 0.3 AU. Discussion is made on the cause for the difference between the asymmetric shock wave in the direction of south-west and symmetrical shock wave. The former may be blast wave, and the latter may be piston driven shock wave and the like. (Iwakiri, K.)

  3. Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2007-03-01

    Full Text Available One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10−8 N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

  4. Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2007-03-01

    Full Text Available One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10−8 N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

  5. The Solar Wind Source Cycle: Relationship to Dynamo Behavior

    Science.gov (United States)

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

    2017-12-01

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

  6. Preferred solar wind emitting longitudes on the sun

    International Nuclear Information System (INIS)

    Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

    1977-01-01

    During the 11 1/2-year period from July 1964 through December 1975, high- and low-speed solar wind flows originated from preferred solar longitudes. The preferred longitude effect was most pronounced from 1970 onward but was also evident in the years preceding 1970. The most pronounced modulation in average solar wind speed with longitude (approximately 20%) was obtained when it was assumed that the synodic rotation period of the sun is 27.025 days. Some deep internal structure in the sun must ultmately be responsible for these long-lived longitudinal effects, which appear to rotate rigidly with the sun

  7. The Yaglom law in the expanding solar wind

    International Nuclear Information System (INIS)

    Gogoberidze, G.; Perri, S.; Carbone, V.

    2013-01-01

    We study the Yaglom law, which relates the mixed third-order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two-scale expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind, two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Elsässer fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third-order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.

  8. The magnetosphere under weak solar wind forcing

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2007-02-01

    Full Text Available The Earth's magnetosphere was very strongly disturbed during the passage of the strong shock and the following interacting ejecta on 21–25 October 2001. These disturbances included two intense storms (Dst*≈−250 and −180 nT, respectively. The cessation of this activity at the start of 24 October ushered in a peculiar state of the magnetosphere which lasted for about 28 h and which we discuss in this paper. The interplanetary field was dominated by the sunward component [B=(4.29±0.77, −0.30±0.71, 0.49±0.45 nT]. We analyze global indicators of geomagnetic disturbances, polar cap precipitation, ground magnetometer records, and ionospheric convection as obtained from SuperDARN radars. The state of the magnetosphere is characterized by the following features: (i generally weak and patchy (in time low-latitude dayside reconnection or reconnection poleward of the cusps; (ii absence of substorms; (iii a monotonic recovery from the previous storm activity (Dst corrected for magnetopause currents decreasing from ~−65 to ~−35 nT, giving an unforced decreased of ~1.1 nT/h; (iv the probable absence of viscous-type interaction originating from the Kelvin-Helmholtz (KH instability; (v a cross-polar cap potential of just 20–30 kV; (vi a persistent, polar cap region containing (vii very weak, and sometimes absent, electron precipitation and no systematic inter-hemisphere asymmetry. Whereas we therefore infer the presence of a moderate amount of open flux, the convection is generally weak and patchy, which we ascribe to the lack of solar wind driver. This magnetospheric state approaches that predicted by Cowley and Lockwood (1992 but has never yet been observed.

  9. Parametric decay of current-driven Langmuir waves in plateau plasmas: Relevance to solar wind and foreshock events

    Science.gov (United States)

    Sauer, Konrad; Malaspina, David M.; Pulupa, Marc; Salem, Chadi S.

    2017-07-01

    Langmuir amplitude modulation in association with type III radio bursts is a well-known phenomenon since the beginning of space observations. It is commonly attributed to the superposition of beam-excited Langmuir waves and their backscattered counterparts as a result of parametric decay. The dilemma, however, is the discrepancy between fast beam relaxation and long-lasting Langmuir wave activity. Instead of starting with an unstable electron beam, our focus in this paper is on the nonlinear response of Langmuir oscillations that are driven after beam stabilization by the still persisting current of the (stable) two-electron plasma. The velocity distribution function of the second population forms a plateau (index h) with a point at which ∂fh/∂v ˜0 associated with weak damping over a more or less extended wave number range k. As shown by particle-in-cell simulations, this so-called plateau plasma drives primarily Langmuir oscillations at the plasma frequency (ωe) with k = 0 over long times without remarkable change of the distribution function. These Langmuir oscillations act as a pump wave for parametric decay by which an electron-acoustic wave slightly below ωe and a counterstreaming ion-acoustic wave are generated. Both high-frequency waves have nearly the same amplitude, which is given by the product of plateau density and velocity. Beating of these two wave types leads to pronounced Langmuir amplitude modulation, in reasonable agreement with solar wind and terrestrial foreshock observations made by the Wind spacecraft.

  10. A model for the origin of solar wind stream interfaces

    International Nuclear Information System (INIS)

    Hundhausen, A.J.; Burlaga, L.F.

    1975-01-01

    The basic variations in solar wind properties that have been observed at 'stream interfaces' near 1 AU are explained by a gas dynamic model in which a radially propagating stream, produced by a temperature variation in the solar envelope, steepens nonlinearly while moving through interplanetary space. The region thus identified with the stream interface separates the ambient solar wind from the fresh hot material originally in the stream. However, the interface regions given by the present model are thicker than most stream interfaces observed in the solar wind, a fact suggesting that some additional physical process may be important in determining that thickness. Variations in the density, speed, or Alfven pressure alone appear not to produce streams with such an interface

  11. SOLAR WIND HEAVY IONS OVER SOLAR CYCLE 23: ACE/SWICS MEASUREMENTS

    International Nuclear Information System (INIS)

    Lepri, S. T.; Landi, E.; Zurbuchen, T. H.

    2013-01-01

    Solar wind plasma and compositional properties reflect the physical properties of the corona and its evolution over time. Studies comparing the previous solar minimum with the most recent, unusual solar minimum indicate that significant environmental changes are occurring globally on the Sun. For example, the magnetic field decreased 30% between the last two solar minima, and the ionic charge states of O have been reported to change toward lower values in the fast wind. In this work, we systematically and comprehensively analyze the compositional changes of the solar wind during cycle 23 from 2000 to 2010 while the Sun moved from solar maximum to solar minimum. We find a systematic change of C, O, Si, and Fe ionic charge states toward lower ionization distributions. We also discuss long-term changes in elemental abundances and show that there is a ∼50% decrease of heavy ion abundances (He, C, O, Si, and Fe) relative to H as the Sun went from solar maximum to solar minimum. During this time, the relative abundances in the slow wind remain organized by their first ionization potential. We discuss these results and their implications for models of the evolution of the solar atmosphere, and for the identification of the fast and slow wind themselves.

  12. Conductive solar wind models in rapidly diverging flow geometries

    International Nuclear Information System (INIS)

    Holzer, T.E.; Leer, E.

    1980-01-01

    A detailed parameter study of conductive models of the solar wind has been carried out, extending the previous similar studies of Durney (1972) and Durney and Hundhausen (1974) by considering collisionless inhibition of thermal conduction, rapidly diverging flow geometries, and the structure of solutions for the entire n 0 -T 0 plane (n 0 and T 0 are the coronal base density and temperature). Primary emphasis is placed on understanding the complex effects of the physical processes operative in conductive solar wind models. There are five points of particular interest that have arisen from the study: (1) neither collisionless inhibition of thermal conduction nor rapidly diverging flow geometries can significantly increase the solar wind speed at 1 AU; (2) there exists a firm upper limit on the coronal base temperature consistent with observed values of the coronal base pressure and solar wind mass flux density; (3) the principal effect of rapidly diverging flow geometries is a decrease in the solar wind mass flux density at 1 AU and an increase in the mass flux density at the coronal base; (4) collisionless inhibition of thermal conduction can lead to a solar wind flow speed that either increases or decreases with increasing coronal base density (n 0 ) and temperature (T 0 , depending on the region of the n 0 -T 0 plane considered; (5) there is a region of the n 0 -T/sub o/ plane at high coronal base densities where low-speed, high-mass-flux, transonic solar wind flows exist: a region not previously considered

  13. Meteoric ions in the corona and solar wind

    International Nuclear Information System (INIS)

    Lemaire, J.

    1990-01-01

    The total mass of refractory material of interplanetary origin penetrating and evaporated in the meltosphere surrounding the sun has been inferred from observations of meteoroids and fireballs falling in earth's atmosphere. The amount of iron atoms deposited this way in the solar corona is of the order of 3000 t/s or larger. The measured flux of outflowing solar wind iron ions is equal to 2200 t/s. The close agreement of both fluxes is evidence that a significant fraction of iron ions observed in the solar wind and in the corona must be of meteoric origin. A similar accord is also obtained for silicon ions. The mean velocity of meteoroid ions formed in the solar corona is equal to the free-fall velocity: i.e., independent of their atomic mass as the thermal speed of heavy ion measured in low-density solar wind streams at 1 AU. Furthermore, the heavy ions of meteoric origin escape out of the corona with a larger bulk velocity than the protons which are mainly of solar origin. These differences of heavy ion and proton bulk velocities are also observed in the solar wind. 52 refs

  14. Solar-wind predictions for the Parker Solar Probe orbit. Near-Sun extrapolations derived from an empirical solar-wind model based on Helios and OMNI observations

    Science.gov (United States)

    Venzmer, M. S.; Bothmer, V.

    2018-03-01

    Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission. Methods: The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner

  15. Solar wind and its interaction with the Earth magnetosphere

    International Nuclear Information System (INIS)

    Grib, S.A.

    1978-01-01

    A critical review is given regarding the research of the stationary and non-stationary interaction of the solar wind with the Earth magnetosphere. Highlighted is the significance of the interplanetary magnetic field in the non-stationary movement of the solar wind flux. The problem of the solar wind shock waves interaction with the ''bow wave-Earth's magnetosphere'' system is being solved. Considered are the secondary phenomena, as a result of which the depression-type wave occurs, that lowers the pressure on the Earth's maanetosphere. The law, governing the movement of the magnetosphere subsolar point during the abrupt start of a geomagnetic storm has been discovered. Stationary circumvention of the magnetosphere by the solar wind flux is well described by the gas dynamic theory of the hypersonic flux. Non-stationary interaction of the solar wind shock waves with the magnetosphere is magnetohydrodynamic. It is pointed out, that the problems under consideration are important for the forecasting of strong geomagnetic perturbations on the basis of cosmic observations

  16. Effect of Alfvenic fluctuations on the solar wind

    International Nuclear Information System (INIS)

    Chien, T.H.

    1974-01-01

    The major source of microscale fluctuations in the interplanetary medium due to the outwardly propagating Alfven waves is considered. The effect of the Alfven waves on the supersonic expansion of the solar wind is studied under the assumption that the motion of the interplanetary medium can be resolved physically into a comparatively smooth and slowly varying mesoscale flow and field with very irregular disordered incompressible microscale Alfvenic fluctuations superposed on it. The important features of the solar wind such as heat conduction flux, spiral interplanetary magnetic field, and proton thermal anisotropy are included in the theory. For inviscid, steady state, spherically symmetrical model of the solar wind, the two-fluid formulation of the background mesoscale MHD equations is obtained. The results show that during the expansion process, fluctuation energy is converted into the kinetic energy of the solar wind. Due to the presence of the Alfvenic fluctuations, the velocity of the solar wind is about 5 percent higher than that without considering the fluctuations. (U.S.)

  17. Wave-trains in the solar wind. III

    International Nuclear Information System (INIS)

    Richter, A.K.

    1975-01-01

    Applying an Alfven-Wave-Extended-QRH-approximation and the method of characteristics, the equations of motion for outwardly propagating Alfven waves are solved analytically for three different cases of an azimuthal dependence of the background solar wind, (a) for a pure fast-slow stream configuration, (b) for the situation where the high-speed stream originates from a diverging magnetic field, and (c) for the case of (b) and an initially decreasing density configuration ('coronal hole'). The reaction of these waves on the background state as well as mode-mode coupling effects are neglected. These three solar wind models are discussed shortly. For the superimposed Alfven waves it is found, on an average, that there is a strong azimuthal dependence of all relevant parameters which, correlated with the azimuthal distributions of the solar wind variables, leads to good agreements with observations. The signature of high-speed streams and these correlations could clearly indicate solar wind streams originating from 'coronal holes'. Contrary to the purely radial solar wind, where outwardly propagating Alfven waves are exclusively refracted towards the radial direction, a refraction nearly perpendicular to the direction of the interplanetary magnetic field in the compression region and closely towards the magnetic field direction down the trailing edge and in the low-speed regime is found. (Auth.)

  18. LONG-TERM TRENDS IN THE SOLAR WIND PROTON MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Heather A.; McComas, David J. [Southwest Research Institute, San Antonio, TX (United States); DeForest, Craig E. [Southwest Research Institute, Boulder, CO (United States)

    2016-11-20

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

  19. A study of the solar wind deceleration in the Earth's foreshock region

    Science.gov (United States)

    Zhang, T.-L.; Schwingenschuh, K.; Russell, C. T.

    1995-01-01

    Previous observations have shown that the solar wind is decelerated and deflected in the earth's upstream region populated by long-period waves. This deceleration is corelated with the 'diffuse' but not with the 'reflected' ion population. The speed of the solar wind may decrease tens of km/s in the foreshock region. The solar wind dynamic pressure exerted on the magnetopause may vary due to the fluctuation of the solar wind speed and density in the foreshock region. In this study, we examine this solar wind deceleration and determine how the solar wind deceleration varies in the foreshock region.

  20. A hybrid reconfigurable solar and wind energy system

    Science.gov (United States)

    Gadkari, Sagar A.

    We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of solar/wind hybrid energy system. The key mechanisms; optics, cooling mechanism of VMJ cells and air flow through the system were investigated using simulation tools. The results from these simulations, along with a simple economic analysis giving the levelized cost of energy for such a system are presented. An iterative method of design refinement based on the simulation results was used to work towards a prototype design. The levelized cost of the system achieved in the economic analysis shows the system to be a good alternative for a grid isolated site and could be used as a standalone system in regions of lower demand. The new approach to solar wind hybrid system reported herein will pave way for newer generation of hybrid systems that share common infrastructure in addition to the storage and distribution of energy.

  1. Weakest solar wind of the space age and the current 'MINI' solar maximum

    International Nuclear Information System (INIS)

    McComas, D. J.; Angold, N.; Elliott, H. A.; Livadiotis, G.; Schwadron, N. A.; Smith, C. W.; Skoug, R. M.

    2013-01-01

    The last solar minimum, which extended into 2009, was especially deep and prolonged. Since then, sunspot activity has gone through a very small peak while the heliospheric current sheet achieved large tilt angles similar to prior solar maxima. The solar wind fluid properties and interplanetary magnetic field (IMF) have declined through the prolonged solar minimum and continued to be low through the current mini solar maximum. Compared to values typically observed from the mid-1970s through the mid-1990s, the following proton parameters are lower on average from 2009 through day 79 of 2013: solar wind speed and beta (∼11%), temperature (∼40%), thermal pressure (∼55%), mass flux (∼34%), momentum flux or dynamic pressure (∼41%), energy flux (∼48%), IMF magnitude (∼31%), and radial component of the IMF (∼38%). These results have important implications for the solar wind's interaction with planetary magnetospheres and the heliosphere's interaction with the local interstellar medium, with the proton dynamic pressure remaining near the lowest values observed in the space age: ∼1.4 nPa, compared to ∼2.4 nPa typically observed from the mid-1970s through the mid-1990s. The combination of lower magnetic flux emergence from the Sun (carried out in the solar wind as the IMF) and associated low power in the solar wind points to the causal relationship between them. Our results indicate that the low solar wind output is driven by an internal trend in the Sun that is longer than the ∼11 yr solar cycle, and they suggest that this current weak solar maximum is driven by the same trend.

  2. Understanding non-equilibrium collisional and expansion effects in the solar wind with Parker Solar Probe

    Science.gov (United States)

    Korreck, K. E.; Klein, K. G.; Maruca, B.; Alterman, B. L.

    2017-12-01

    The evolution of the solar wind from the corona to the Earth and throughout the heliosphere is a complex interplay between local micro kinetics and large scale expansion effects. These processes in the solar wind need to be separated in order to understand and distinguish the dominant mechanism for heating and acceleration of the solar wind. With the upcoming launch in 2018 of Parker Solar Probe and the launch of Solar Orbiter after, addressing the local and global phenomena will be enabled with in situ measurements. Parker Solar Probe will go closer to the Sun than any previous mission enabling the ability to examine the solar wind at an early expansion age. This work examines the predictions for what will be seen inside of the 0.25 AU (54 solar radii) where Parker Solar Probe will take measurements and lays the groundwork for disentangling the expansion and collisional effects. In addition, methods of thermal plasma data analysis to determine the stability of the plasma in the Parker Solar Probe measurements will be discussed.

  3. Distribution and solar wind control of compressional solar wind-magnetic anomaly interactions observed at the Moon by ARTEMIS

    Science.gov (United States)

    Halekas, J. S.; Poppe, A. R.; Lue, C.; Farrell, W. M.; McFadden, J. P.

    2017-06-01

    A statistical investigation of 5 years of observations from the two-probe Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission reveals that strong compressional interactions occur infrequently at high altitudes near the ecliptic but can form in a wide range of solar wind conditions and can occur up to two lunar radii downstream from the lunar limb. The compressional events, some of which may represent small-scale collisionless shocks ("limb shocks"), occur in both steady and variable interplanetary magnetic field (IMF) conditions, with those forming in steady IMF well organized by the location of lunar remanent crustal magnetization. The events observed by ARTEMIS have similarities to ion foreshock phenomena, and those observed in variable IMF conditions may result from either local lunar interactions or distant terrestrial foreshock interactions. Observed velocity deflections associated with compressional events are always outward from the lunar wake, regardless of location and solar wind conditions. However, events for which the observed velocity deflection is parallel to the upstream motional electric field form in distinctly different solar wind conditions and locations than events with antiparallel deflections. Consideration of the momentum transfer between incoming and reflected solar wind populations helps explain the observed characteristics of the different groups of events.Plain Language SummaryWe survey the environment around the Moon to determine when and where strong amplifications in the charged particle density and magnetic field strength occur. These structures may be some of the smallest shock waves in the solar system, and learning about their formation informs us about the interaction of charged particles with small-scale magnetic fields throughout the solar system and beyond. We find that these compressions occur in an extended region downstream from the lunar dawn and dusk regions and

  4. Ulysses solar wind plasma observations at high southerly latitudes.

    Science.gov (United States)

    Phillips, J L; Bame, S J; Feldman, W C; Gosling, J T; Hammond, C M; McComas, D J; Goldstein, B E; Neugebauer, M; Scime, E E; Suess, S T

    1995-05-19

    Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.

  5. Coupling of the solar wind to measures of magnetic activity

    International Nuclear Information System (INIS)

    McPherron, R.L.; Fay, R.A.; Garrity, C.R.; Bargatze, L.F.; Baker, D.N.; Clauer, C.R.; Searls, C.

    1984-01-01

    The technique of linear prediction filtering has been used to generate empirical response functions relating the solar wind electric field to the most frequently used magnetic indices, AL, AU, Dst and ASYM. Two datasets, one from 1967-1968 and one from 1973-1974, provided the information needed to calculate the empirical response functions. These functions have been convolved with solar wind observations obtained during the IMS to predict the indices. These predictions are compared with the observed indices during two, three-day intervals studied extensively by participants in the CDAW-6 workshop. Differences between the observed and predicted indices are discussed in terms of the linear assumption and in terms of physical processes other than direct solar wind-magnetosphere interaction

  6. Solar wind power electric plant on Vis (Croatia)

    International Nuclear Information System (INIS)

    1998-01-01

    A project of a solar photovoltaic electric power plant presented by the Republic of Croatia at the meeting of the E.P.I.A. Mission for photovoltaic technology of the Mediterranean countries, aroused a great interest of the representatives of the invited countries. However, the interest within Croatia in the project has disappeared although E.P.I.A. offered a financing of two thirds of costs. There are attempts to construct 1800 kw wind-driven generators at the same location not taking into consideration a possibility of building a hybrid solar-wind-power electric plant. The chance that the solar part is completely of domestic origin is not accepted but the preference is given to the building of imported wind-driven generators. (orig.)

  7. Effects of electrons on the solar wind proton temperature anisotropy

    International Nuclear Information System (INIS)

    Michno, M. J.; Lazar, M.; Schlickeiser, R.; Yoon, P. H.

    2014-01-01

    Among the kinetic microinstabilities, the firehose instability is one of the most efficient mechanisms to restrict the unlimited increase of temperature anisotropy in the direction of an ambient magnetic field as predicted by adiabatic expansion of collision-poor solar wind. Indeed, the solar wind proton temperature anisotropy detected near 1 AU shows that it is constrained by the marginal firehose condition. Of the two types of firehose instabilities, namely, parallel and oblique, the literature suggests that the solar wind data conform more closely to the marginal oblique firehose condition. In the present work, however, it is shown that the parallel firehose instability threshold is markedly influenced by the presence of anisotropic electrons, such that under some circumstances, the cumulative effects of both electron and proton anisotropies could describe the observation without considering the oblique firehose mode.

  8. Average properties of cosmic ray diffusion in solar wind streams

    International Nuclear Information System (INIS)

    Morfill, G.; Richter, A.K.; Scholer, M.

    1979-01-01

    Applying a superposed epoch analysis to the Mariner 5 plasma and magnetic field observations of 13 corotating high speed solar wind streams, we obtain the average azimuthal distribution of all relevant parameters of the background interplanetary medium, as well as those of superimposed Alfven waves. Using these measurements in model calculations allows us to determine the radial and azimuthal variation of the background and fluctuation parameters between 1 and 5 AU, and thus to calculate the cosmic ray diffusion coefficient kappa from the plasma and field properties. The calculation of kappa assumes that quasi-linear wave-particle interaction theory is applicable, and that the Alfven waves responsible for the scattering are propagating in the azimuthally varying solar wind according to geometrical optics. The consequences of these calculations regarding the occurrence of solar wind stream associated Forbush decreases are discussed

  9. THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Nicolaou, G., E-mail: helliott@swri.edu [Swedish Institute of Space Physics, Box 812, SE-98128, Kiruna (Sweden)

    2016-04-15

    The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.

  10. THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

    International Nuclear Information System (INIS)

    Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G.; Nicolaou, G.

    2016-01-01

    The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun

  11. Magnetic fields in the solar system planets, moons and solar wind interactions

    CERN Document Server

    Wicht, Johannes; Gilder, Stuart; Holschneider, Matthias

    2018-01-01

    This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors an...

  12. The turbulent cascade and proton heating in the solar wind during solar minimum

    International Nuclear Information System (INIS)

    Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J.; Stawarz, Joshua E.; Forman, Miriam A.

    2013-01-01

    Solar wind measurements at 1 AU during the recent solar minimum and previous studies of solar maximum provide an opportunity to study the effects of the changing solar cycle on in situ heating. Our interest is to compare the levels of activity associated with turbulence and proton heating. Large-scale shears in the flow caused by transient activity are a source that drives turbulence that heats the solar wind, but as the solar cycle progresses the dynamics that drive the turbulence and heat the medium are likely to change. The application of third-moment theory to Advanced Composition Explorer (ACE) data gives the turbulent energy cascade rate which is not seen to vary with the solar cycle. Likewise, an empirical heating rate shows no significan changes in proton heating over the cycle.

  13. Agua Caliente Wind/Solar Project at Whitewater Ranch

    Energy Technology Data Exchange (ETDEWEB)

    Hooks, Todd [Agua Caliente Band of Cahuilla Indians, Palm Springs, CA (United States); Stewart, Royce [Red Mountain Energy Partners, Sante Fe, NM (United States)

    2014-12-16

    Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly has excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.

  14. Kinetic Properties of Solar Wind Silicon and Iron Ions

    Science.gov (United States)

    Janitzek, N. P.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

    2017-12-01

    Heavy ions with atomic numbers Z>2 account for less than one percent of the solar wind ions. However, serving as test particles with differing mass and charge, they provide a unique experimental approach to major questions of solar and fundamental plasma physics such as coronal heating, the origin and acceleration of the solar wind and wave-particle interaction in magnetized plasma. Yet the low relative abundances of the heavy ions pose substantial challenges to the instrumentation measuring these species with reliable statistics and sufficient time resolution. As a consequence the numbers of independent measurements and studies are small. The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) is a linear time-of-flight mass spectrometer which was operated at Lagrangian point L1 in 1996 for a few months only, before it suffered an instrument failure. Despite its short operation time, the CTOF sensor measured solar wind heavy ions with excellent charge state separation, an unprecedented cadence of 5 minutes and very high counting statistics, exceeding similar state-of-the-art instruments by a factor of ten. In contrast to earlier CTOF studies which were based on reduced onboard post-processed data, in our current studies we use raw Pulse Height Analysis (PHA) data providing a significantly increased mass, mass-per-charge and velocity resolution. Focussing on silicon and iron ion measurements, we present an overview of our findings on (1) short time behavior of heavy ion 1D radial velocity distribution functions, (2) differential streaming between heavy ions and solar wind bulk protons, (3) kinetic temperatures of heavy ions. Finally, we compare the CTOF results with measurements of the Solar Wind Ion Composition Spectrometer (SWICS) instrument onboard the Advanced Composition Explorer (ACE).

  15. Formation of Heliospheric Arcs of Slow Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Higginson, A. K.; Zurbuchen, T. H. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Antiochos, S. K.; DeVore, C. R. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wyper, P. F., E-mail: aleida@umich.edu [Department of Mathematical Sciences, Durham University, Durham DH1 3LE (United Kingdom)

    2017-05-01

    A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

  16. Solar wind velocity and daily variation of cosmic rays

    International Nuclear Information System (INIS)

    Ahluwalia, H.S.; Riker, J.F.

    1985-01-01

    Recently parameters applicable to the solar wind and the interplanetary magnetic field (IMF) have become much better defined. Superior quality of data bases that are now available, particularly for the post-1971 period, make it possible to believe the long-term trends in the data. These data are correlated with the secular changes observed in the diurnal variation parameters obtained from neutron monitor data at Deep River and underground muon telescope data at Embudo (30 MEW) and Socorro (82 MWE). The annual mean amplitudes appear to have large values during the epochs of high speed solar wind streams. Results are discussed

  17. Flank solar wind interaction. Annual report, June 1991-July 1992

    International Nuclear Information System (INIS)

    Moses, S.L.; Greenstadt, E.W.

    1992-08-01

    This report summarizes the results of the first 12 months of our program to study the interaction of the Earth's magnetosphere with the solar wind on the far flanks of the bow shock. This study employs data from the ISEE-3 spacecraft during its traversals of the Earth's magnetotail and correlative data from spacecraft monitoring the solar wind upstream. Our main effort to date has involved assembling data sets and developing new plotting programs. Two talks were given at the Spring Meeting of the American Geophysical Union describing our initial results from analyzing data from the far flank foreshock and magnetosheath. The following sections summarize our results

  18. ANALYSING SOLAR-WIND HYBRID POWER GENERATING SYSTEM

    Directory of Open Access Journals (Sweden)

    Mustafa ENGİN

    2005-02-01

    Full Text Available In this paper, a solar-wind hybrid power generating, system that will be used for security lighting was designed. Hybrid system was installed and solar cells, wind turbine, battery bank, charge regulators and inverter performance values were measured through the whole year. Using measured values of overall system efficiency, reliability, demanded energy cost per kWh were calculated, and percentage of generated energy according to resources were defined. We also include in the paper a discussion of new strategies to improve hybrid power generating system performance and demanded energy cost per kWh.

  19. Dependence of Substorm Evolution on Solar Wind Condition: Simulation Study

    Science.gov (United States)

    Kamiyoshikawa, N.; Ebihara, Y.; Tanaka, T.

    2017-12-01

    A substorm is one of the remarkable disturbances occurring in the magnetosphere. It is known that the substorm occurs frequently when IMF is southward and solar wind speed is high. However, the physical process to determine substorm scale is not well understood. We reproduced substorms by using global MHD simulation, calculated auroral electrojet (ionospheric Hall current) flowing in the ionosphere to investigate the dependence of substorm evolution on solar wind condition. Solar wind speed of 372.4 km/s and IMF Bz of 5.0 nT were imposed to, obtain the quasi-stationary state of the magnetosphere. Then the solar wind parameters were changed as a step function. For the solar wind speed, we assumed 300 km/s, 500 km/s and 700 km/s. For IMF, we assumed -1.0 nT, -3.0 nT, -5.0 nT, -7.0 nT and -9.0 nT. In total, 15 simulation runs were performed. In order to objectively evaluate the substorm, the onset was identified with the method based on the one proposed by Newell et al. (2011). This method uses the SME index that is an extension of the AE index. In this study, the geomagnetic variation induced by the ionospheric Hall current was obtained every 1 degree from the magnetic latitude 40 degrees to 80 degrees and in every 0.5 hours in the magnetic region direction. The upper and the lower envelopes of the geomagnetic variation are regarded as SMU index and SML index, respectively. The larger the solar wind speed, the larger the southward IMF, the more the onset tends to be faster. This tendency is consistent with the onset occurrence probability indicated by Newell et al. (2016). Moreover, the minimum value of the SML index within 30 minutes from the beginning of the onset tends to decrease with the solar wind speed and the magnitude of the southward IMF. A rapid decrease of the SML index can be explained by a rapid increase in the field-aligned currents flowing in and out of the nightside ionosphere. This means that electromagnetic energies flowing into the ionosphere

  20. Solar wind plasma structure near a 'HELIOS-Perihelion'

    International Nuclear Information System (INIS)

    Kikuchi, H.

    1979-01-01

    The purpose of this paper is to introduce a couple of preliminary but important results obtained from HELIOS observation concerning solar wind plasma structure near a ''HELIOS-Perihelion'' among the data analyses in progress, partly in relation to laboratory plasma. Idealized profiles of the bulk velocity, density and temperature of solar wind near 0.3 AU as deduced from HELIOS A data and correlated K-coronal contours were obtained. During 1974 - 1976, the sun was in the period of declining cycle, and the coronal holes expanded to lower latitudes from northern and southern holes. There is general tendency that the northern coronal hole is somewhat larger than the southern coronal hole. In regards to solar wind velocity, there are two fast stream regions with velocity as high as 800 Km/sec. An electron spectrum measured near a HELIOS-Perihelion (0.3 AU) approximately in the solar direction is shown. Three regions can be distinguished in velocity distribution. The density contours of solar wind electrons in velocity space exhibit a narrow beam of electrons in the magnetic field direction close to the plane of observation. (Kato, T.)

  1. Harmonic analysis and suppression in hybrid wind & PV solar system

    Science.gov (United States)

    Gupta, Tripti; Namekar, Swapnil

    2018-04-01

    The growing demand of electricity has led to produce power through non-conventional source of energy such as solar energy, wind energy, hydro power, energy through biogas and biomass etc. Hybrid system is taken to complement the shortcoming of either sources of energy. The proposed system is grid connected hybrid wind and solar system. A 2.1 MW Doubly fed Induction Generator (DFIG) has been taken for analysis of wind farm whose rotor part is connected to two back-to-back converters. A 250 KW Photovoltaic (PV) array taken to analyze solar farm where inverter is required to convert power from DC to AC since electricity generated through solar PV is in the form of DC. Stability and reliability of the system is very important when the system is grid connected. Harmonics is the major Power quality issue which degrades the quality of power at load side. Harmonics in hybrid system arise through the use of power conversion unit. The other causes of harmonics are fluctuation in wind speed and solar irradiance. The power delivered to grid must be free from harmonics and within the limits specified by Indian grid codes. In proposed work, harmonic analysis of the hybrid system is performed in Electrical Transient Analysis program (ETAP) and single tuned harmonic filter is designed to maintain the utility grid harmonics within limits.

  2. CHARACTERIZATION OF TRANSITIONS IN THE SOLAR WIND PARAMETERS

    International Nuclear Information System (INIS)

    Perri, S.; Balogh, A.

    2010-01-01

    The distinction between fast and slow solar wind streams and the dynamically evolved interaction regions is reflected in the characteristic fluctuations of both the solar wind and the embedded magnetic field. High-resolution magnetic field data from the Ulysses spacecraft have been analyzed. The observations show rapid variations in the magnetic field components and in the magnetic field strength, suggesting a structured nature of the solar wind at small scales. The typical sizes of fluctuations cover a broad range. If translated to the solar surface, the scales span from the size of granules (∼10 3 km) and supergranules (∼10 4 km) on the Sun down to ∼10 2 km and less. The properties of the short time structures change in the different types of solar wind. While fluctuations in fast streams are more homogeneous, slow streams present a bursty behavior in the magnetic field variances, and the regions of transition are characterized by high levels of power in narrow structures around the transitions. The probability density functions of the magnetic field increments at several scales reveal a higher level of intermittency in the mixed streams, which is related to the presence of well localized features. It is concluded that, apart from the differences in the nature of fluctuations in flows of different coronal origin, there is a small-scale structuring that depends on the origin of streams themselves but it is also related to a bursty generation of the fluctuations.

  3. GPP Webinar: Market Outlook and Innovations in Wind and Solar Power

    Science.gov (United States)

    Green Power Partnership webinar reviewing the state of the renewable energy industry as a whole, with a focus on wind and solar power and exploring recent marketplace innovations in wind and solar power and renewable energy purchases.

  4. Power generation from wind turbines in a solar chimney

    Energy Technology Data Exchange (ETDEWEB)

    Foote, Tudor [Graduate Student, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States); Agarwal, Ramesh K. [William Palm Professor, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States)

    2013-07-01

    Recent studies have shown that shrouded wind turbines can generate greater power compared to bare turbines. A solar chimney generates an upward draft of wind inside a tower and a shroud around the wind turbine. There are numerous empty silos on farms in the U.S. that can be converted to solar chimneys with minor modifications at modest cost. The objective of this study is to determine the potential of these silos/chimneys for generating wind power. The study is conducted through analytical/computational approach by employing the commercial Computational Fluid Dynamics (CFD) software. Computations are performed for five different geometric configurations consisting of a turbine, a cylindrical silo, and/or a venturi and/or a diffuser using the dimensions of typical silos and assuming Class 3 wind velocity. The incompressible Navier-Stokes equations with the Boussinesq approximation and a two equation realizable {kappa}-{epsilon} model are employed in the calculations, and the turbine is modeled as an actuator disk. The power coefficient (Cp) and generated power are calculated for the five cases. Consistent with recent literature, it was found that the silos with diffusers increase the Cp beyond Betz’s limit significantly and thus the generated power. It should be noted that Cp is calculated by normalizing it by the turbine area swept by the wind. This study shows the potential of using abandoned silos in the mid-west and other parts of the country for localized wind power generation.

  5. A Model fot the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S. K.; Mikic, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2011-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to approx.60deg, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. Key words: solar wind - Sun: corona - Sun: magnetic topology

  6. Turbulence and Waves as Sources for the Solar Wind

    Science.gov (United States)

    Cranmer, S. R.

    2008-05-01

    Gene Parker's insights from 50 years ago provided the key causal link between energy deposition in the solar corona and the acceleration of solar wind streams. However, the community is still far from agreement concerning the actual physical processes that give rise to this energy. It is still unknown whether the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy is input more intermittently from closed loops into the open-field regions. No matter the relative importance of reconnections and loop-openings, though, we do know that waves and turbulent motions are present everywhere from the photosphere to the heliosphere, and it is important to determine how they affect the mean state of the plasma. In this presentation, I will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona (and the fast and slow solar wind). The coronal heating and solar wind acceleration in these models comes from anisotropic turbulent cascade, which is driven by the partial reflection of low-frequency Alfven waves propagating along the open magnetic flux tubes. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above Parker's critical point. As predicted by earlier studies, a larger coronal expansion factor gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. Finally, I will outline the types of future observations that would be most able to test and refine these ideas.

  7. Elemental composition and ionization state of the solar atmosphere and solar wind

    International Nuclear Information System (INIS)

    Joselyn, J.A.C.

    1978-01-01

    Abundance measurements have always proved useful in generating and refining astrophysical theories. Some of the classical problems of astrophysics involve determining the relative abundances of elements in the atmosphere of a star from observations of its line spectrum, and then synthesizing the physical processes which would produce such abundances. Theories of the formation of the solar system are critically tested by their ability to explain observed abundances, and, elemental abundances can serve as tracers, helping to determine the origin and transport of ions. Since the solar wind originates at the sun, it can act as a diagnostic probe of solar conditions. In particular, measurements of the composition of the solar wind should be related to the solar composition. And, assuming ionization equilibrium, measurements of the relative abundances of the ionization states in the solar wind should infer coronal temperatures and temperature gradients. However, most spherically symmetric models of the solar wind are unable to explain the relationship between the composition estimated from solar observations and as measured at 1 AU; and, recent observations of significant flow speeds in the transition region raise doubts about the validity of the assumption of ionization equilibrium

  8. A comparison of solar wind streams and coronal structure near solar minimum

    Science.gov (United States)

    Nolte, J. T.; Davis, J. M.; Gerassimenko, M.; Lazarus, A. J.; Sullivan, J. D.

    1977-01-01

    Solar wind data from the MIT detectors on the IMP 7 and 8 satellites and the SOLRAD 11B satellite for the solar-minimum period September-December, 1976, were compared with X-ray images of the solar corona taken by rocket-borne telescopes on September 16 and November 17, 1976. There was no compelling evidence that a coronal hole was the source of any high speed stream. Thus it is possible that either coronal holes were not the sources of all recurrent high-speed solar wind streams during the declining phase of the solar cycle, as might be inferred from the Skylab period, or there was a change in the appearance of some magnetic field regions near the time of solar minimum.

  9. Origin of the Wang-Sheeley-Arge solar wind model

    Science.gov (United States)

    Sheeley, Neil R., Jr.

    2017-03-01

    A correlation between solar wind speed at Earth and the amount of magnetic field line expansion in the corona was verified in 1989 using 22 years of solar and interplanetary observations. We trace the evolution of this relationship from its birth 15 years earlier in the Skylab era to its current use as a space weather forecasting technique. This paper is the transcript of an invited talk at the joint session of the Historical Astronomy Division and the Solar Physics Division of the American Astronomical Society during its 224th meeting in Boston, MA, on 3 June 2014.

  10. Solar wind flows associated with hot heavy ions

    International Nuclear Information System (INIS)

    Fenimore, E.E.

    1980-05-01

    Solar wind heavy ion spectra measured with the Vela instrumentation have been studied with the goal of determining the solar origins of various solar wind structures which contain anomalously high ionization states. Since the ionization states freeze-in close to the sun they are good indicators of the plasma conditions in the low and intermediate corona. Heavy ion spectra from three different periods throughout the solar cycle have been analyzed. These data are consistent with freezing-in temperatures ranging from approx. 1.5 x 10 6 K to higher than 9 x 10 6 . The spectra indicating hot coronal conditions occur in roughly 1/7 of all measurements and almost exclusively in postshock flows (PSFs), nonshock related helium abundance enhancements (HAEs), or noncompressive density enhancements (NCDEs). The PSFs and HAEs are both probably interplanetary manifestations of solar flares. The observation of several flare-related HAEs which were not preceded by an interplanetary shock suggests that the flare-heated plasma can evolve into the solar wind without producing a noticeable shock at 1 AU. The NCDEs with hot heavy ions differ from the PSF-HAEs in several ways implying that they evolve from events or places with lower temperatures and less energy than those associated with the flares, but with higher temperatures and densities than the quiet corona. Active regions, coronal mass ejections, and equatorial streamers are possible sources for the NCDEs with spectra indicating hot coronal conditions. These events owe their enhanced densities to coronal processes as opposed to interplanetary dynamical processes. Models of the solar wind expansion demonstrate how some NCDEs can have extreme, nonequilibrium ionization distributions

  11. The "FIP Effect" and the Origins of Solar Energetic Particles and of the Solar Wind

    OpenAIRE

    Reames, Donald V.

    2018-01-01

    We find that the element abundances in solar energetic particles (SEPs) and in the slow solar wind (SSW), relative to those in the photosphere, show different patterns as a function of the first ionization potential (FIP) of the elements. Generally, the SEP and SSW abundances reflect abundance samples of the solar corona, where low-FIP elements, ionized in the chromosphere, are more efficiently conveyed upward to the corona than high-FIP elements that are initially neutral atoms. Abundances o...

  12. EVOLUTION OF THE RELATIONSHIPS BETWEEN HELIUM ABUNDANCE, MINOR ION CHARGE STATE, AND SOLAR WIND SPEED OVER THE SOLAR CYCLE

    International Nuclear Information System (INIS)

    Kasper, J. C.; Stevens, M. L.; Korreck, K. E.; Maruca, B. A.; Kiefer, K. K.; Schwadron, N. A.; Lepri, S. T.

    2012-01-01

    The changing relationships between solar wind speed, helium abundance, and minor ion charge state are examined over solar cycle 23. Observations of the abundance of helium relative to hydrogen (A He ≡ 100 × n He /n H ) by the Wind spacecraft are used to examine the dependence of A He on solar wind speed and solar activity between 1994 and 2010. This work updates an earlier study of A He from 1994 to 2004 to include the recent extreme solar minimum and broadly confirms our previous result that A He in slow wind is strongly correlated with sunspot number, reaching its lowest values in each solar minima. During the last minimum, as sunspot numbers reached their lowest levels in recent history, A He continued to decrease, falling to half the levels observed in slow wind during the previous minimum and, for the first time observed, decreasing even in the fastest solar wind. We have also extended our previous analysis by adding measurements of the mean carbon and oxygen charge states observed with the Advanced Composition Explorer spacecraft since 1998. We find that as solar activity decreased, the mean charge states of oxygen and carbon for solar wind of a given speed also fell, implying that the wind was formed in cooler regions in the corona during the recent solar minimum. The physical processes in the coronal responsible for establishing the mean charge state and speed of the solar wind have evolved with solar activity and time.

  13. Wind and solar energy curtailment: A review of international experience

    DEFF Research Database (Denmark)

    Bird, Lori; Lew, Debra; Milligan, Michael

    2016-01-01

    Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases....

  14. NEMO 2 - Be aware: Wind and solar are coming

    Energy Technology Data Exchange (ETDEWEB)

    Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland)

    1996-12-31

    Finnish research and development is well placed with respect to new renewable energy technologies in that there exists considerable expertise in specialized areas. For example, over 20 % of all power transmission equipment and generators used in wind energy systems world-wide are manufactured in Finland, while advanced instruments for monitoring wind speed are also highly regarded internationally. Moreover, unique wind technology for complex windy and freezing conditions have been developed. Finland has a 10 % share in the European photovoltaic market, and has competitive advantages in photovoltaic systems and applications, thin film solar cells, and automated electronic controlling systems. A unique solar energy storage system based on hydrogen technology demonstrates skills on overcoming the summer-winter syndrome of large-scale solar energy utilization. The annual turnover of the Finnish industries on solar and wind energy has increased from 5 million ECU in 1988 to almost 50 million ECU in 1996. The national R and D and D from 1988 onwards has played an important role in this context. Most of the research and development into new and renewable energy technologies in Finland has been carried out through the Advanced New Energy Systems and Technologies Research Programme (NEMO2) of Tekes

  15. Signatures of kinetic instabilities in the solar wind

    Czech Academy of Sciences Publication Activity Database

    Matteini, L.; Hellinger, Petr; Goldstein, B. E.; Landi, S.; Velli, M.; Neugebauer, M.

    2013-01-01

    Roč. 118, č. 6 (2013), s. 2771-2782 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2023 Grant - others:EU(XE) SHOCK Project No. 284515 Institutional support: RVO:67985815 Keywords : solar wind ions * numerical simulations * kinetic instabities Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.440, year: 2013

  16. Imprint of the Sun on the Solar Wind

    Science.gov (United States)

    Woo, R.; Habbal, S. R.

    1998-01-01

    Observations of the inner corona in polarized brightness by the Mauna Loa MkIII K-coronameter and soft X-ray by Yohkoh of the inner corona are combined with Ulysses radio occultation measurements of the solar wind to demonstrate that the signature of active regions and bright points is present in the heliocentric distance range of 10-30 Ro.

  17. Kinetic instabilities in the solar wind driven by temperature anisotropies

    Science.gov (United States)

    Yoon, Peter H.

    2017-12-01

    The present paper comprises a review of kinetic instabilities that may be operative in the solar wind, and how they influence the dynamics thereof. The review is limited to collective plasma instabilities driven by the temperature anisotropies. To limit the scope even further, the discussion is restricted to the temperature anisotropy-driven instabilities within the model of bi-Maxwellian plasma velocity distribution function. The effects of multiple particle species or the influence of field-aligned drift will not be included. The field-aligned drift or beam is particularly prominent for the solar wind electrons, and thus ignoring its effect leaves out a vast portion of important physics. Nevertheless, for the sake of limiting the scope, this effect will not be discussed. The exposition is within the context of linear and quasilinear Vlasov kinetic theories. The discussion does not cover either computer simulations or data analyses of observations, in any systematic manner, although references will be made to published works pertaining to these methods. The scientific rationale for the present analysis is that the anisotropic temperatures associated with charged particles are pervasively detected in the solar wind, and it is one of the key contemporary scientific research topics to correctly characterize how such anisotropies are generated, maintained, and regulated in the solar wind. The present article aims to provide an up-to-date theoretical development on this research topic, largely based on the author's own work.

  18. A Review of Hybrid Solar PV and Wind Energy System

    Directory of Open Access Journals (Sweden)

    Rashid Al Badwawi

    2015-07-01

    Full Text Available Due to the fact that solar and wind power is intermittent and unpredictable in nature, higher penetration of their types in existing power system could cause and create high technical challenges especially to weak grids or stand-alone systems without proper and enough storage capacity. By integrating the two renewable resources into an optimum combination, the impact of the variable nature of solar and wind resources can be partially resolved and the overall system becomes more reliable and economical to run. This paper provides a review of challenges and opportunities / solutions of hybrid solar PV and wind energy integration systems. Voltage and frequency fluctuation, and harmonics are major power quality issues for both grid-connected and stand-alone systems with bigger impact in case of weak grid. This can be resolved to a large extent by having proper design, advanced fast response control facilities, and good optimization of the hybrid systems. The paper gives a review of the main research work reported in the literature with regard to optimal sizing design, power electronics topologies and control. The paper presents a review of the state of the art of both grid-connected and stand-alone hybrid solar and wind systems.

  19. Solar Wind Monitor--A School Geophysics Project

    Science.gov (United States)

    Robinson, Ian

    2018-01-01

    Described is an established geophysics project to construct a solar wind monitor based on a nT resolution fluxgate magnetometer. Low-cost and appropriate from school to university level it incorporates elements of astrophysics, geophysics, electronics, programming, computer networking and signal processing. The system monitors the earth's field in…

  20. Review Space Weather and Solar Wind Studies with OWFA

    Indian Academy of Sciences (India)

    In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy .... complex flow of solar wind at different time and spa- ..... in a step of ∼20 .... observing program with the legacy system of the ORT.

  1. Solar wind reconstruction from magnetosheath data using an adjoint approach

    International Nuclear Information System (INIS)

    Nabert, C.; Othmer, C.

    2015-01-01

    We present a new method to reconstruct solar wind conditions from spacecraft data taken during magnetosheath passages, which can be used to support, e.g., magnetospheric models. The unknown parameters of the solar wind are used as boundary conditions of an MHD (magnetohydrodynamics) magnetosheath model. The boundary conditions are varied until the spacecraft data matches the model predictions. The matching process is performed using a gradient-based minimization of the misfit between data and model. To achieve this time-consuming procedure, we introduce the adjoint of the magnetosheath model, which allows efficient calculation of the gradients. An automatic differentiation tool is used to generate the adjoint source code of the model. The reconstruction method is applied to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data to calculate the solar wind conditions during spacecraft magnetosheath transitions. The results are compared to actual solar wind data. This allows validation of our reconstruction method and indicates the limitations of the MHD magnetosheath model used.

  2. Solar wind reconstruction from magnetosheath data using an adjoint approach

    Energy Technology Data Exchange (ETDEWEB)

    Nabert, C.; Othmer, C. [Technische Univ. Braunschweig (Germany). Inst. fuer Geophysik und extraterrestrische Physik; Glassmeier, K.H. [Technische Univ. Braunschweig (Germany). Inst. fuer Geophysik und extraterrestrische Physik; Max Planck Institute for Solar System Research, Goettingen (Germany)

    2015-07-01

    We present a new method to reconstruct solar wind conditions from spacecraft data taken during magnetosheath passages, which can be used to support, e.g., magnetospheric models. The unknown parameters of the solar wind are used as boundary conditions of an MHD (magnetohydrodynamics) magnetosheath model. The boundary conditions are varied until the spacecraft data matches the model predictions. The matching process is performed using a gradient-based minimization of the misfit between data and model. To achieve this time-consuming procedure, we introduce the adjoint of the magnetosheath model, which allows efficient calculation of the gradients. An automatic differentiation tool is used to generate the adjoint source code of the model. The reconstruction method is applied to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data to calculate the solar wind conditions during spacecraft magnetosheath transitions. The results are compared to actual solar wind data. This allows validation of our reconstruction method and indicates the limitations of the MHD magnetosheath model used.

  3. Magnetosheath Propagation Time of Solar Wind Directional Discontinuities

    Science.gov (United States)

    Samsonov, A. A.; Sibeck, D. G.; Dmitrieva, N. P.; Semenov, V. S.; Slivka, K. Yu.; Å afránkova, J.; Němeček, Z.

    2018-05-01

    Observed delays in the ground response to solar wind directional discontinuities have been explained as the result of larger than expected magnetosheath propagation times. Recently, Samsonov et al. (2017, https://doi.org/10.1002/2017GL075020) showed that the typical time for a southward interplanetary magnetic field (IMF) turning to propagate across the magnetosheath is 14 min. Here by using a combination of magnetohydrodynamic simulations, spacecraft observations, and analytic calculations, we study the dependence of the propagation time on solar wind parameters and near-magnetopause cutoff speed. Increases in the solar wind speed result in greater magnetosheath plasma flow velocities, decreases in the magnetosheath thickness and, as a result, decreases in the propagation time. Increases in the IMF strength result in increases in the magnetosheath thickness and increases in the propagation time. Both magnetohydrodynamic simulations and observations suggest that propagation times are slightly smaller for northward IMF turnings. Magnetosheath flow deceleration must be taken into account when predicting the arrival times of solar wind structures at the dayside magnetopause.

  4. Air emissions due to wind and solar power.

    Science.gov (United States)

    Katzenstein, Warren; Apt, Jay

    2009-01-15

    Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve approximately 80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30-50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability.

  5. Solar wind oscillations with a 1.3 year period

    Science.gov (United States)

    Richardson, John D.; Paularena, Karolen I.; Belcher, John W.; Lazarus, Alan J.

    1994-01-01

    The Interplanetary Monitoring Platform 8 (IMP-8) and Voyager 2 spacecraft have recently detected a very strong modulation in the solar wind speed with an approximately 1.3 year period. Combined with evidence from long-term auroral and magnetometer studies, this suggests that fundamental changes in the Sun occur on a roughly 1.3 year time scale.

  6. Electron energetics in the expanding solar wind via Helios observations

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Trávníček, Pavel M.; Hellinger, Petr

    2015-01-01

    Roč. 120, č. 10 (2015), s. 8177-8193 ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : solar wind plasma * plasma energization * transport processes Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.318, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2015JA021368/abstract

  7. Electron energetics in the expanding solar wind via Helios observations

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Trávníček, Pavel M.; Hellinger, Petr

    2015-01-01

    Roč. 120, č. 10 (2015), s. 8177-8193 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041; GA ČR GA15-17490S Institutional support: RVO:67985815 Keywords : solar wind * electrons energetics * transport processes Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.318, year: 2015

  8. Enigmatic Solar Wind Disappearance Events – Do We Understand ...

    Indian Academy of Sciences (India)

    Solar wind disappearance—polar field reversals—transient ... unlike its high speed counterpart that emanates only from large open field regions ..... Sheeley, N. R. Jr., Swanson, E. T., Wang, Y.-M. 1991, Out of the ecliptic tests of the inverse.

  9. Theoretical contributions to solar wind research - a review

    International Nuclear Information System (INIS)

    Cuperman, S.

    1977-01-01

    The theoretical work on the solar wind phenomena done since 1958 can be divided into two main parts: Part I - development and refinement of Parker's initial macroscopic model, the emphasis being placed upon steady state, spherically symmetric flow and the identification of the structure-less background solar wind plasma with the low speed flow. It is in this part that much progress in understanding the solar wind phenomenon has been achieved; Part II - generalization of Parker's initial model such as to include microscopic (kinetic) aspects, temporal variations, deviations from spherically symmetric conditions, complex local magnetic configurations, etc. The last two aspects, in particular, have received considerable attention with the discovery of the coronal holes, their association with high-speed flows and the tentative identification of these flows with the structure-less background solar wind plasma. This review is confined to Part I, as defined above. However, for completeness, several important aspects connected with the subjects enumerated under Part II and which represent the objects of the most recent investigation are also briefly reviewed. (Auth.)

  10. Depletion of solar wind plasma near a planetary boundary

    International Nuclear Information System (INIS)

    Zwan, B.J.; Wolf, R.A.

    1976-01-01

    A mathematical model is presented that describes the squeezing of solar wind plasma out along interplanetary magnetic field lines in the region between the bow shock and the effective planetary boundary (in the case of the earth, the magnetopause). In the absence of local magnetic merging the squeezing process should create a 'depletion layer,' a region of very low plasma density just outside the magnetopause. Numerical solutions are obtained for the dimensionless magnetohydrodynamic equations describing this depletion process for the case where the solar wind magnetic field is perpendicular to the solar wind flow direction. For the case of the earth with a magnetopause standoff distance of 10 R/subE/, the theory predicts that the density should be reduced by a factor > or =2 in a layer about 700--1300 km thick if M/subA/, the Alfven Mach number in the solar wind, is equal to 8. The layer thickness should vary as M/subA/ -2 and should be approximately uniform for a large area of the magnetopause around the subsolar point. Computed layer thicknesses are somewhat smaller than those derived from Lees' axisymmetric model. Depletion layers should develop fully only where magnetic merging is locally unimportant. Scaling of the model calculations to Venus and Mars suggest layer thicknesses about 1/10 and 1/15 those of the earth, respectively, neglecting diffusion and ionospheric effects

  11. Solar wind heat flux regulation by the whistler instability

    International Nuclear Information System (INIS)

    Gary, S.P.; Feldman, W.C.

    1977-01-01

    This paper studies the role of the whistler instability in the regulation of the solar wind heat flux near 1 AU. A comparison of linear and second-order theory with experimental results provides strong evidence that the whistler may at times contribute to the limitation of this heat flux

  12. Proton thermal energetics in the solar wind: Helios reloaded

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, P.; Štverák, Štěpán; Matteini, L.; Velli, M.

    2013-01-01

    Roč. 118, č. 4 (2013), s. 1351-1365 ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : solar wind * proton energetics * turbulent heating Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/jgra.50107/abstract

  13. Solar wind dynamic pressure variations and transient magnetospheric signatures

    International Nuclear Information System (INIS)

    Sibeck, D.G.; Baumjohann, W.

    1989-01-01

    Contrary to the prevailing popular view, we find some transient ground events with bipolar north-south signatures are related to variations in solar wind dynamic pressure and not necessarily to magnetic merging. We present simultaneous solar wind plasma observations for two previously reported transient ground events observed at dayside auroral latitudes. During the first event, originally reported by Lanzerotti et al. [1987], conjugate ground magnetometers recorded north-south magetic field deflections in the east-west and vertical directions. The second event was reported by Todd et al. [1986], we noted ground rader observations indicating strong northward then southward ionospheric flows. The events were associated with the postulated signatures of patchy, sporadic, merging of magnetosheath and magnetospheric magnetic field lines at the dayside magnetospause, known as flux transfer events. Conversely, we demonstrate that the event reported by Lanzerotti et al. was accompanied by a sharp increase in solar wind dynamic pressure, a magnetospheric compression, and a consequent ringing of the magnetospheric magnetic field. The event reported by Todd et al. was associated with a brief but sharp increase in the solar wind dynamic pressure. copyright American Geophysical Union 1989

  14. Remote Sensing of the Heliospheric Solar Wind using Radio ...

    Indian Academy of Sciences (India)

    tribpo

    Astr. (2000) 21, 439–444. Remote Sensing of the Heliospheric Solar Wind using Radio. Astronomy Methods and Numerical Simulations. S. Ananthakrishnan, National Center for Radio Astrophysics, Tata Institute of. Fundamental Research, Pune, India. Abstract. The ground-based radio astronomy method of interplanetary.

  15. Solar wind charge exchange observed through the lunar exosphere

    Czech Academy of Sciences Publication Activity Database

    Robertson, I. P.; Sembay, S.; Stubbs, T. J.; Kuntz, K. D.; Collier, M. R.; Cravens, T. E.; Snowden, S. L.; Hills, H. K.; Porter, F. S.; Trávníček, Pavel M.; Carter, J. A.; Read, A. M.

    2009-01-01

    Roč. 36, - (2009), L21102/1-L21102/5 ISSN 0094-8276 Institutional research plan: CEZ:AV0Z30420517 Keywords : lunar exosphere * solar wind * X-rays Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.204, year: 2009

  16. Study on Pyroelectric Harvesters Integrating Solar Radiation with Wind Power

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2015-07-01

    Full Text Available Pyroelectric harvesters use temperature fluctuations to generate electrical outputs. Solar radiation and waste heat are rich energy sources that can be harvested. Pyroelectric energy converters offer a novel and direct energy-conversion technology by transforming time-dependent temperatures directly into electricity. Moreover, the great challenge for pyroelectric energy harvesting lies in finding promising temperature variations or an alternating thermal loading in real situations. Hence, in this article, a novel pyroelectric harvester integrating solar radiation with wind power by the pyroelectric effect is proposed. Solar radiation is a thermal source, and wind is a dynamic potential. A disk generator is used for harvesting wind power. A mechanism is considered to convert the rotary energy of the disk generator to drive a shutter for generating temperature variations in pyroelectric cells using a planetary gear system. The optimal period of the pyroelectric cells is 35 s to harvest the stored energy, about 70 μJ, while the rotary velocity of the disk generator is about 31 RPM and the wind speed is about 1 m/s. In this state, the stored energy acquired from the pyroelectric harvester is about 75% more than that from the disk generator. Although the generated energy of the proposed pyroelectric harvester is less than that of the disk generator, the pyroelectric harvester plays a complementary role when the disk generator is inactive in situations of low wind speed.

  17. 3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?

    Science.gov (United States)

    Verdini, Andrea; Grappin, Roland; Alexandrova, Olga; Lion, Sonny

    2018-01-01

    We study the anisotropy with respect to the local magnetic field of turbulent magnetic fluctuations at magnetofluid scales in the solar wind. Previous measurements in the fast solar wind obtained axisymmetric anisotropy, despite that the analysis method allows nonaxisymmetric structures. These results are probably contaminated by the wind expansion that introduces another symmetry axis, namely, the radial direction, as indicated by recent numerical simulations. These simulations also show that while the expansion is strong, the principal fluctuations are in the plane perpendicular to the radial direction. Using this property, we separate 11 yr of Wind spacecraft data into two subsets characterized by strong and weak expansion and determine the corresponding turbulence anisotropy. Under strong expansion, the small-scale anisotropy is consistent with the Goldreich & Sridhar critical balance. As in previous works, when the radial symmetry axis is not eliminated, the turbulent structures are field-aligned tubes. Under weak expansion, we find 3D anisotropy predicted by the Boldyrev model, that is, turbulent structures are ribbons and not tubes. However, the very basis of the Boldyrev phenomenology, namely, a cross-helicity increasing at small scales, is not observed in the solar wind: the origin of the ribbon formation is unknown.

  18. Solar-wind krypton and solid/gas fractionation in the early solar nebula

    Science.gov (United States)

    Wiens, Roger C.; Burnett, D. S.; Neugebauer, M.; Pepin, R. O.

    1991-01-01

    The solar-system Kr abundance is calculated from solar-wind noble-gas ratios, determined previously by low-temperature oxidations of lunar ilmenite grains, normalized to Si by spacecraft solar-wind measurements. The estimated Kr-83 abundance of 4.1 + or - 1.5 per million Si atoms is within uncertainty of estimates assuming no fractionation, determined from CI-chondrite abundances of surrounding elements. This is significant because it is the first such constraint on solid/gas fractionation, though the large uncertainty only confines it to somewhat less than a factor of two.

  19. Signature of open magnetic field lines in the extended solar corona and of solar wind acceleration

    Science.gov (United States)

    Antonucci, E.; Giordano, S.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S.

    1997-01-01

    The observations carried out with the ultraviolet coronagraph spectrometer onboard the Solar and Heliospheric Observatory (SOHO) are discussed. The purpose of the observations was to determine the line of sight and radial velocity fields in coronal regions with different magnetic topology. The results showed that the regions where the high speed solar wind flows along open field lines are characterized by O VI 1032 and HI Lyman alpha 1216 lines. The global coronal maps of the line of sight velocity were reconstructed. The corona height, where the solar wind reaches 100 km/s, was determined.

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

    International Nuclear Information System (INIS)

    Manoharan, P. K.

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

    The solar wind was originally envisioned using a simple dipolar corona/polar coronal hole sources picture, but modern observations and models, together with the recent unusual solar cycle minimum, have demonstrated the limitations of this picture. The solar surface fields in both polar and low-to-mid-latitude active region zones routinely produce coronal magnetic fields and related solar wind sources much more complex than a dipole. This makes low-to-mid latitude coronal holes and their associated streamer boundaries major contributors to what is observed in the ecliptic and affects the Earth. In this paper we use magnetogram-based coronal field models to describe the conditions that prevailed in the corona from the decline of cycle 23 into the rising phase of cycle 24. The results emphasize the need for adopting new views of what is ‘typical’ solar wind, even when the Sun is relatively inactive. PMID:25685422

  2. Reactor aspects of counterstreaming-ion tokamak plasmas

    International Nuclear Information System (INIS)

    Jassby, D.L.

    1975-06-01

    Toroidal DT plasmas in which the D and T ions make up two distinct, quasi-thermal velocity distributions, oppositely displaced in velocity along the magnetic axis, are discussed. Such counterstreaming distributions can be set up by introducing all ions by tangential injection of neutral beams, and by removing ions from the plasma shortly after they have decelerated to an energy approximate to or less than 2T/sub e/ by Coulomb drag on the plasma electrons. A simple physical model for counterstreaming-ion operation is postulated, which allows one to deduce the ion velocity distributions and required energy and particle confinement times that are in good agreement with the results of previous Fokker-Planck calculations. The variations of fusion reactivity, power gain, and power density with injection energy and electron temperature are presented. The practical problems of implementing counter-streaming operation in a tokamak, such as charge-exchange losses, the prompt removal of cold ions, and the effect of impurities are discussed. (U.S.)

  3. Solar-wind system powers mountain clean-up

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    By using a hybrid solar-wind system, the Japanese have tackled the problem of human excrement left by tourists in mountain lodges and in natural parks by installing flush toilets and wastewater treatment plants. The solar array (4.9 kW{sub p}) consists of 76 panels of single-crystal photovoltaic cells each with an output of 64 Wp. The wind turbines (total capacity 2.1 kW) operate whatever the wind strength or direction. Storage batteries prevent any dip in power which would result from low ambient temperatures. The system can still function at temperatures as low as minus 25{sup o}C. Between November and April when the lodge is closed, the waste is decomposed biologically. A block diagram shows the elements of the system, and details of cost are given. The system won the 1999 New Energy Award.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  5. High-speed solar wind flow parameters at 1 AU

    International Nuclear Information System (INIS)

    Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

    1976-01-01

    To develop a set of constraints for theories of solar wind high-speed streams, a detailed study was made of the fastest streams observed at 1 AU during the time period spanning March 1971 through July 1974. Streams were accepted for study only if (1) the maximum speed exceeded 650 km s -1 ; (2) effects of stream-stream dynamical interaction on the flow parameters could be safely separated from the intrinsic characteristics of the high-speed regions; (3) the full width at half maximum (FWHM) of the stream when mapped back to 20 solar radii by using a constant speed approximation was greater than 45degree in Carrington longitude; and (4) there were no obvious solar-activity-induced contaminating effects. Nineteen streams during this time interval satisfied these criteria. Average parameters at 1 AU for those portions of these streams above V=650 km s -1 are given.Not only is it not presently known why electrons are significantly cooler than the protons within high-speed regions, but also observed particle fluxes and convected energy fluxes for speed greater than 650 km s -1 are substantially larger than those values predicted by any of the existing theories of solar wind high-speed streams. More work is therefore needed in refining present solar wind models to see whether suitable modifications and/or combinations of existing theories based on reasonable coronal conditions can accommodate the above high-speed flow parameters

  6. Sustainable business models for wind and solar energy in Romania

    Directory of Open Access Journals (Sweden)

    Nichifor Maria Alexandra

    2015-06-01

    Full Text Available Renewable energy has become a crucial element for the business environment as the need for new energy resources and the degree of climate change are increasing. As developed economies strive towards greater progress, sustainable business models are of the essence in order to maintain a balance between the triple bottom line: people, planet and profit. In recent years, European Union countries have installed important capacities of renewable energy, especially wind and solar energy to achieve this purpose. The objective of this article is to make a comparative study between the current sustainable business models implemented in companies that are active in the wind and solar energy sector in Romania. Both sectors underwent tremendous changes in the last two years due to changing support schemes which have had a significant influence on the mechanism of the renewable energy market, as well as on its development. Using the classical Delphi method, based on questionnaires and interviews with experts in the fields of wind and solar energy, this paper offers an overview of the sustainable business models of wind and solar energy companies, both sectors opting for the alternative of selling electricity to trading companies as a main source of revenue until 2013 and as the main future trend until 2020. Furthermore, the participating wind energy companies noted a pessimistic outlook of future investments due to legal instability that made them to reduce their projects in comparison to PV investments, which are expected to continue. The subject of the article is of interest to scientific literature because sustainable business models in wind and photovoltaic energy have been scarcely researched in previous articles and are essential in understanding the activity of the companies in these two fields of renewable energy.

  7. Data Assimilation in the Solar Wind: Challenges and First Results.

    Science.gov (United States)

    Lang, Matthew; Browne, Philip; van Leeuwen, Peter Jan; Owens, Mathew

    2017-11-01

    Data assimilation (DA) is used extensively in numerical weather prediction (NWP) to improve forecast skill. Indeed, improvements in forecast skill in NWP models over the past 30 years have directly coincided with improvements in DA schemes. At present, due to data availability and technical challenges, DA is underused in space weather applications, particularly for solar wind prediction. This paper investigates the potential of advanced DA methods currently used in operational NWP centers to improve solar wind prediction. To develop the technical capability, as well as quantify the potential benefit, twin experiments are conducted to assess the performance of the Local Ensemble Transform Kalman Filter (LETKF) in the solar wind model ENLIL. Boundary conditions are provided by the Wang-Sheeley-Arge coronal model and synthetic observations of density, temperature, and momentum generated every 4.5 h at 0.6 AU. While in situ spacecraft observations are unlikely to be routinely available at 0.6 AU, these techniques can be applied to remote sensing of the solar wind, such as with Heliospheric Imagers or interplanetary scintillation. The LETKF can be seen to improve the state at the observation location and advect that improvement toward the Earth, leading to an improvement in forecast skill in near-Earth space for both the observed and unobserved variables. However, sharp gradients caused by the analysis of a single observation in space resulted in artificial wavelike structures being advected toward Earth. This paper is the first attempt to apply DA to solar wind prediction and provides the first in-depth analysis of the challenges and potential solutions.

  8. Solar wind stream interaction regions throughout the heliosphere

    Science.gov (United States)

    Richardson, Ian G.

    2018-01-01

    This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ˜ 0.3-1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed.

  9. Resistive instabilities of current sheets in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Dobrowolny, M [CNR, Laboratorio per il Plasma nello Spazio, Frascati, Italy; Trussoni, E [CNR, Laboratorio di Cosmo-Geofisica, Turin, Italy

    1979-03-01

    Resistive magnetohydrodynamic instabilities are investigated numerically for non-antisymmetric magnetic field profiles similar to those indicated in spacecraft data on solar wind discontinuities. The eigenvalue problem derived for the growth rate of possible instabilities from dimensionless equations for velocity and magnetic field perturbations is solved starting from the outer regions where the plasma is frozen to the magnetic field. For an antisymmetric magnetic profile, calculations show only tearing modes to be present, with instabilities occurring only at long wavelengths, while for a non-antisymmetric magnetic profile resembling the observed solar wind, calculations indicate the presence of rippling modes driven by resistivity gradients, in addition to the tearing modes. Calculations of the scale lengths of variation of the reversing component based on a scaling law relating the maximum growth rate to the magnetic Reynolds number are found to agree with observed solar current sheet scale lengths.

  10. Transport of transient solar wind particles in Earth's cusps

    International Nuclear Information System (INIS)

    Parks, G. K.; Lee, E.; Teste, A.; Wilber, M.; Lin, N.; Canu, P.; Dandouras, I.; Reme, H.; Fu, S. Y.; Goldstein, M. L.

    2008-01-01

    An important problem in space physics still not understood well is how the solar wind enters the Earth's magnetosphere. Evidence is presented that transient solar wind particles produced by solar disturbances can appear in the Earth's mid-altitude (∼5 R E geocentric) cusps with densities nearly equal to those in the magnetosheath. That these are magnetosheath particles is established by showing they have the same ''flattop'' electron distributions as magnetosheath electrons behind the bow shock. The transient ions are moving parallel to the magnetic field (B) toward Earth and often coexist with ionospheric particles that are flowing out. The accompanying waves include electromagnetic and broadband electrostatic noise emissions and Bernstein mode waves. Phase-space distributions show a mixture of hot and cold electrons and multiple ion species including field-aligned ionospheric O + beams

  11. Global aspects of stream evolution in the solar wind

    International Nuclear Information System (INIS)

    Gosling, J.T.

    1984-01-01

    A spatially variable coronal expansion, when coupled with solar rotation, leads to the formation of high speed solar wind streams which evolve considerably with increasing heliocentric distance. Initially the streams steepen for simple kinematic reasons, but this steepening is resisted by pressure forces, leading eventually to the formation of forward-reverse shock pairs in the distant heliosphere. The basic physical processes responsible for stream steepening an evolution are explored and model calculations are compared with actual spacecraft observations of the process. The solar wind stream evolution problem is relatively well understood both observationally and theoretically. Tools developed in achieving this understanding should be applicable to other astrophysical systems where a spatially or temporally variable outflow is associated with a rotating object. 27 references, 13 figures

  12. Applying Nyquist's method for stability determination to solar wind observations

    Science.gov (United States)

    Klein, Kristopher G.; Kasper, Justin C.; Korreck, K. E.; Stevens, Michael L.

    2017-10-01

    The role instabilities play in governing the evolution of solar and astrophysical plasmas is a matter of considerable scientific interest. The large number of sources of free energy accessible to such nearly collisionless plasmas makes general modeling of unstable behavior, accounting for the temperatures, densities, anisotropies, and relative drifts of a large number of populations, analytically difficult. We therefore seek a general method of stability determination that may be automated for future analysis of solar wind observations. This work describes an efficient application of the Nyquist instability method to the Vlasov dispersion relation appropriate for hot, collisionless, magnetized plasmas, including the solar wind. The algorithm recovers the familiar proton temperature anisotropy instabilities, as well as instabilities that had been previously identified using fits extracted from in situ observations in Gary et al. (2016). Future proposed applications of this method are discussed.

  13. Solar wind fluctuations at large scale: A comparison between low and high solar activity conditions

    International Nuclear Information System (INIS)

    Bavassano, B.; Bruno, R.

    1991-01-01

    The influence of the Sun's activity cycle on the solar wind fluctuations at time scales from 1 hour to 3 days in the inner heliosphere (0.3 to 1 AU) is investigated. Hourly averages of plasma and magnetic field data by Helios spacecraft are used. Since fluctuations behave quite differently with changing scale, the analysis is performed separately for two different ranges in time scale. Between 1 and 6 hours Alfvenic fluctuations and pressure-balanced structures are extensively observed. At low solar activity and close to 0.3 AU, Alfvenic fluctuations are more frequent than pressure-balanced structures. This predominance, however, weakens for rising solar activity and radial distance, to the point that a role exchange, in terms of occurrence rate, is found at the maximum of the cycle close to 1 AU. On the other hand, in all cases Alfvenic fluctuations have a larger amplitude than pressure-balanced structures. On the whole, the Alfvenic contribution to the solar wind energy spectrum comes out to be dominant at all solar activity conditions. At scales from 0.5 to 3 days the most important feature is the growth, as the solar wind expansion develops, of strong positive correlations between magnetic and thermal pressures. These structures are progressively built up by the interaction between different wind flows. This effect is more pronounced at low than at high activity. Our findings support the conclusion that the solar cycle evolution of the large-scale velocity pattern is the factor governing the observed variations

  14. THE CONTRIBUTION OF CORONAL JETS TO THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Lionello, R.; Török, T.; Titov, V. S.; Mikić, Z.; Linker, J. A. [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Leake, J. E.; Linton, M. G., E-mail: lionel@predsci.com [US Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375 (United States)

    2016-11-01

    Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulations to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4–3.0)% and (0.3–1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.

  15. WSA-Enlil Solar Wind Prediction

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — WSA-Enlil is a large-scale, physics-based prediction model of the heliosphere, used by the Space Weather Forecast Office to provide 1-4 day advance warning of solar...

  16. Predicting Atmospheric Ionization and Excitation by Precipitating SEP and Solar Wind Protons Measured By MAVEN

    Science.gov (United States)

    Jolitz, Rebecca; Dong, Chuanfei; Lee, Christina; Lillis, Rob; Brain, David; Curry, Shannon; Halekas, Jasper; Bougher, Stephen W.; Jakosky, Bruce

    2017-10-01

    Precipitating energetic particles ionize and excite planetary atmospheres, increasing electron content and producing aurora. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutral and pass the magnetosheath, and SEPs are sufficiently energetic to cross the magnetosheath unchanged. We will compare ionization and Lyman alpha emission rates for solar wind and SEP protons during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare excitation and ionization rates by SEPs and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help quantify how SEP and solar wind protons influence atmospheric energy deposition during solar minimum.

  17. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    International Nuclear Information System (INIS)

    Gold, R.E.; Dodson-Prince, H.W.; Hedeman, E.R.; Roelof, E.C.

    1982-01-01

    We have studied solar and interplanetary data by identification of the heliographic longitudes of the coronal source regions of high speed solar wind streams and by mapping the velocities measured near earth back to the sun using the approximation of constant radial velocity. Interplay of active regions and solar wind were studied

  18. Solar Panel Buffeted by Wind at Phoenix Site

    Science.gov (United States)

    2008-01-01

    Winds were strong enough to cause about a half a centimeter (.19 inch) of motion of a solar panel on NASA's Phoenix Mars lander when the lander's Surface Stereo Imager took this picture on Aug. 31, 2008, during the 96th Martian day since landing. The lander's telltale wind gauge has been indicating wind speeds of about 4 meters per second (9 miles per hour) during late mornings at the site. These conditions were anticipated and the wind is not expected to do any harm to the lander. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  19. The solar wind in time: a change in the behaviour of older winds?

    Science.gov (United States)

    O'Fionnagáin, D.; Vidotto, A. A.

    2018-05-01

    In this paper, we model the wind of solar analogues at different ages to investigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages, whereby stars older than the Sun would be less efficient in carrying away angular momentum than what was traditionally believed. Adding to this, recent observations suggest that old solar-type stars show a break in coronal properties, with a steeper decay in X-ray luminosities and temperatures at older ages. We use these X-ray observations to constrain the thermal acceleration of winds of solar analogues. Our sample is based on the stars from the `Sun in Time' project with ages between 120 and 7000 Myr. The break in X-ray properties leads to a break in wind mass-loss rates (\\dot{M}) at roughly 2 Gyr, with \\dot{M} (t 2 Gyr) ∝ t-3.9. This steep decay in \\dot{M} at older ages could be the reason why older stars are less efficient at carrying away angular momentum, which would explain the anomalously rapid rotation observed in older stars. We also show that none of the stars in our sample would have winds dense enough to produce thermal emission above 1-2 GHz, explaining why their radio emissions have not yet been detected. Combining our models with dynamo evolution models for the magnetic field of the Earth, we find that, at early ages (≈100 Myr), our Earth had a magnetosphere that was three or more times smaller than its current size.

  20. Solar-wind interactions with the Moon: role of oxygen ions

    International Nuclear Information System (INIS)

    Mukherjee, N.R.

    1979-01-01

    The solar-wind interacts directly with the lunar surface due to tenuous atmosphere and magnetic field. The interaction results in an almost complete absorption of the solar-wind corpuscles producing no upstream bowshock but a cavity downstream. The solar-wind oxygen ionic species induce and undergo a complex set of reactions with the elements of the lunar minerals and the solar-wind derived trapped gases. In this paper, the long-term concentration and the role of oxygen derived from the solar-wind is discussed. (Auth.)

  1. Heating of Solar Wind Ions via Cyclotron Resonance

    Science.gov (United States)

    Navarro, R.; Moya, P. S.; Figueroa-Vinas, A.; Munoz, V.; Valdivia, J. A.

    2017-12-01

    Remote and in situ observations in the solar wind show that ion and electron velocity distributions persistently deviate from thermal equilibrium in the form of relative streaming between species components, temperature anisotropy, etc. These non-thermal features represent a source of free energy for the excitation of kinetic instabilities and fluctuations in the plasma. In this regard, it is believed that plasma particles can be heated, through a second order Fermi acceleration process, by multiple resonances with unstable counter-propagating field-aligned Ion-cyclotron waves. For multi-species plasmas, several collective wave modes participate in this process. In this work, we test this model by studying the percentage of ions that resonate with the waves modes described by the proper kinetic multi-species dispersion relation in a solar-wind-like plasma composed of electrons, protons, and alpha particles. Numerical results are compared with WIND spacecraft data to test its relevance for the existence of thresholds for the preferential perpendicular heating of He+2 ions as observed in the solar wind fast streams.

  2. The "FIP Effect" and the Origins of Solar Energetic Particles and of the Solar Wind

    Science.gov (United States)

    Reames, Donald V.

    2018-03-01

    We find that the element abundances in solar energetic particles (SEPs) and in the slow solar wind (SSW), relative to those in the photosphere, show different patterns as a function of the first ionization potential (FIP) of the elements. Generally, the SEP and SSW abundances reflect abundance samples of the solar corona, where low-FIP elements, ionized in the chromosphere, are more efficiently conveyed upward to the corona than high-FIP elements that are initially neutral atoms. Abundances of the elements, especially C, P, and S, show a crossover from low to high FIP at {≈} 10 eV in the SEPs but {≈} 14 eV for the solar wind. Naively, this seems to suggest cooler plasma from sunspots beneath active regions. More likely, if the ponderomotive force of Alfvén waves preferentially conveys low-FIP ions into the corona, the source plasma that eventually will be shock-accelerated as SEPs originates in magnetic structures where Alfvén waves resonate with the loop length on closed magnetic field lines. This concentrates FIP fractionation near the top of the chromosphere. Meanwhile, the source of the SSW may lie near the base of diverging open-field lines surrounding, but outside of, active regions, where such resonance does not exist, allowing fractionation throughout the chromosphere. We also find that energetic particles accelerated from the solar wind itself by shock waves at corotating interaction regions, generally beyond 1 AU, confirm the FIP pattern of the solar wind.

  3. Detection of fast nanoparticles in the solar wind

    International Nuclear Information System (INIS)

    Meyer-Vernet, N.; Maksimovic, M.; Lecacheux, A.; Le Chat, G.; Czechowski, A.; Mann, I.; Goetz, K.; Kaiser, M. L.; Cyr, O. C. St.; Bale, S. D.

    2010-01-01

    Dust grains in the nanometer range bridge the gap between atoms and larger grains made of bulk material. Their small size embodies them with special properties. Due to their high relative surface area, they have a high charge-to-mass ratio, so that the Lorentz force in the solar wind magnetic field exceeds the gravitational force and other forces by a large amount, and they are accelerated to a speed of the order of magnitude of the solar wind speed. When such fast nanoparticles impact a spacecraft, they produce craters whose matter vaporises and ionises, yielding transient voltages as high as do much larger grains of smaller speed. These properties are at the origin of their recent detection at 1 AU in the solar wind. We discuss the detection of fast nanoparticles by wave instruments of different configurations, with applications to the recent detections on STEREO/WAVES and CASSINI/RPWS. Finally we discuss the opportunities for nanoparticle detection by wave instruments on future missions and/or projects in the inner heliosphere such as Bepi-Colombo and Solar Orbiter.

  4. Invited article: Electric solar wind sail: toward test missions.

    Science.gov (United States)

    Janhunen, P; Toivanen, P K; Polkko, J; Merikallio, S; Salminen, P; Haeggström, E; Seppänen, H; Kurppa, R; Ukkonen, J; Kiprich, S; Thornell, G; Kratz, H; Richter, L; Krömer, O; Rosta, R; Noorma, M; Envall, J; Lätt, S; Mengali, G; Quarta, A A; Koivisto, H; Tarvainen, O; Kalvas, T; Kauppinen, J; Nuottajärvi, A; Obraztsov, A

    2010-11-01

    The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

  5. Geometry of the solar wind transition region during the 11-year solar cycle

    International Nuclear Information System (INIS)

    Lotova, N.A.; Blums, D.F.

    1986-01-01

    Geometry of the solar wind transition region and its dynamics during the 11-year solar cycle is investigated. It is shown that the space geometry of the transition region suffers considerable changes. In the years of minimum of solar activity (1975-1977) the transition region has a form close to elliptical, shifts nearer to the Sun, while its width decreases. During the years of maximum of Solar activity (1979-1981) the form of the transition region becomes close to spherically symmetric, is located further from the Sun and its width is increased

  6. On the relation between ionospheric winter anomalies and solar wind

    International Nuclear Information System (INIS)

    Rumi, G.C.

    2001-01-01

    There are two different winter anomalies. A small one that appears in connection with ionization at relatively low latitudes in the bottom of the D-region of the ionosphere. There, the electron densities in the winter happen to be less than should be expected. On the other hand, the classic winter anomaly is present when in the winter the upper D-region, again at relatively low latitudes, has more ionization than should be expected. Both these effects are due to the slant compression of the geomagnetic field produced by the solar wind in the wind in the winter season (which is, of course, the summer season when reference is made to events in the other hemisphere). It is shown that the small winter anomaly is a consequence of a hemispheric imbalance in the flux of galactic cosmic rays determined by the obliquely distorted geomagnetic field. It is shown that the standard winter anomaly can be ascribed to the influx of a super solar wind, which penetrates into the Earth's polar atmosphere down to E-region, heights and, duly concentrated through a funneling action at the winter pole of the distorted geomagnetic field, slows down the winter polar vortex. An equatorward motion of the polar air with its content of nitric oxide brings about the excess of ionization in the upper D-region at lower latitudes. The experimentally observed rhythmic recurrence of the upper winter anomaly is correlated to a possible rhythmic recurrence of the super solar wind. The actual detection of the upper winter anomaly could yield some information on the velocity of the basic solar wind. A by-product of the present analysis, the determination of Γ, the coefficient of collisional detachment of the electrons from the O 2 - ions, is presented in the Appendix

  7. On the relation between ionospheric winter anomalies and solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Rumi, G.C. [Lecco, (Italy)

    2001-06-01

    There are two different winter anomalies. A small one that appears in connection with ionization at relatively low latitudes in the bottom of the D-region of the ionosphere. There, the electron densities in the winter happen to be less than should be expected. On the other hand, the classic winter anomaly is present when in the winter the upper D-region, again at relatively low latitudes, has more ionization than should be expected. Both these effects are due to the slant compression of the geomagnetic field produced by the solar wind in the wind in the winter season (which is, of course, the summer season when reference is made to events in the other hemisphere). It is shown that the small winter anomaly is a consequence of a hemispheric imbalance in the flux of galactic cosmic rays determined by the obliquely distorted geomagnetic field. It is shown that the standard winter anomaly can be ascribed to the influx of a super solar wind, which penetrates into the Earth's polar atmosphere down to E-region, heights and, duly concentrated through a funneling action at the winter pole of the distorted geomagnetic field, slows down the winter polar vortex. An equatorward motion of the polar air with its content of nitric oxide brings about the excess of ionization in the upper D-region at lower latitudes. The experimentally observed rhythmic recurrence of the upper winter anomaly is correlated to a possible rhythmic recurrence of the super solar wind. The actual detection of the upper winter anomaly could yield some information on the velocity of the basic solar wind. A by-product of the present analysis, the determination of {gamma}, the coefficient of collisional detachment of the electrons from the O{sub 2} {sup -} ions, is presented in the Appendix.

  8. A Generalized Equatorial Model for the Accelerating Solar Wind

    Science.gov (United States)

    Tasnim, S.; Cairns, Iver H.; Wheatland, M. S.

    2018-02-01

    A new theoretical model for the solar wind is developed that includes the wind's acceleration, conservation of angular momentum, deviations from corotation, and nonradial velocity and magnetic field components from an inner boundary (corresponding to the onset of the solar wind) to beyond 1 AU. The model uses a solution of the time-steady isothermal equation of motion to describe the acceleration and analytically predicts the Alfvénic critical radius. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1-27 August 2010. The resulting data-driven model demonstrates the existence of noncorotating, nonradial flows and fields from the inner boundary (r = rs) outward and predicts the magnetic field B = (Br,Bϕ), velocity v = (vr,vϕ), and density n(r,ϕ,t), which vary with heliocentric distance r, heliolatitude ϕ, and time t in a Sun-centered standard inertial plane. The description applies formally only in the equatorial plane. In a frame corotating with the Sun, the transformed velocity v' and a field B' are not parallel, resulting in an electric field with a component Ez' along the z axis. The resulting E'×B'=E'×B drift lies in the equatorial plane, while the ∇B and curvature drifts are out of the plane. Together these may lead to enhanced scattering/heating of sufficiently energetic particles. The model predicts that deviations δvϕ from corotation at the inner boundary are common, with δvϕ(rs,ϕs,ts) comparable to the transverse velocities due to granulation and supergranulation motions. Abrupt changes in δvϕ(rs,ϕs,ts) are interpreted in terms of converging and diverging flows at the cell boundaries and centers, respectively. Large-scale variations in the predicted angular momentum demonstrate that the solar wind can drive vorticity and turbulence from near the Sun to 1 AU and beyond.

  9. Western Wind and Solar Integration Study: Hydropower Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Acker, T.; Pete, C.

    2012-03-01

    The U.S. Department of Energy's (DOE) study of 20% Wind Energy by 2030 was conducted to consider the benefits, challenges, and costs associated with sourcing 20% of U.S. energy consumption from wind power by 2030. This study found that with proactive measures, no insurmountable barriers were identified to meet the 20% goal. Following this study, DOE and the National Renewable Energy Laboratory (NREL) conducted two more studies: the Eastern Wind Integration and Transmission Study (EWITS) covering the eastern portion of the U.S., and the Western Wind and Solar Integration Study (WWSIS) covering the western portion of the United States. The WWSIS was conducted by NREL and research partner General Electric (GE) in order to provide insight into the costs, technical or physical barriers, and operational impacts caused by the variability and uncertainty of wind, photovoltaic, and concentrated solar power when employed to serve up to 35% of the load energy in the WestConnect region (Arizona, Colorado, Nevada, New Mexico, and Wyoming). WestConnect is composed of several utility companies working collaboratively to assess stakeholder and market needs to and develop cost-effective improvements to the western wholesale electricity market. Participants include the Arizona Public Service, El Paso Electric Company, NV Energy, Public Service of New Mexico, Salt River Project, Tri-State Generation and Transmission Cooperative, Tucson Electric Power, Xcel Energy and the Western Area Power Administration.

  10. Solar and wind potentialities in Mauritania. Presentation of pumping

    International Nuclear Information System (INIS)

    Adell, A.; Fagel, L.

    1996-01-01

    The programs of rural hydraulics based upon the use of renewable energies, either solar or wind, have gained in importance in Africa during the last decade; particularly in Mauritania, a Sahelian country, which is extending widely beyond the western edge of Sahara. This country has been hardly affected by the prolonged droughts which have recently struck this region. Water is a major problem here. Important projects appeared concerning the pumping of water with the help of solar photovoltaic systems and wind mechanical pumps; other processes are being studied: pumping with aero-generators, sea water desalinating... Today Mauritania is at the top of countries of the subregion concerning the number of installations of wind mechanical pumps. The meteorological conditions are in fact favourable to such realizations. A technical and economic comparative study of the results of functioning obtained on the field with a photovoltaic pumping installation and a wind pumping installation, is presented: better technical performances and greater reliability for the photovoltaic pump, lower cost and technological mastery for the wind pump. (author). 9 refs., 8 figs

  11. A Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, S. K.; Mikić, Z.; Titov, V. S.; Lionello, R.; Linker, J. A.

    2011-04-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~60°, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model.

  12. Observations of the solar wind speed near the sun

    International Nuclear Information System (INIS)

    Grall, R. R.; Coles, Wm. A.; Klinglesmith, M. T.

    1996-01-01

    Two-antenna scintillation (IPS) observations can provide accurate measurements of the velocity with which electron density fluctuations drift past the line of sight. These fluctuations can be used as tracers for the solar plasma and allow us to estimate the solar wind velocity near the Sun where spacecraft have not yet penetrated. We present recent IPS measurements made with the EISCAT and VLBA arrays. We have found that by using baselines which are several times the scale size of the diffraction pattern we are able to partially deconvolve the line of sight integration which affects remote sensing data. The long baselines allow the fast and slow components of the solar wind to be separated and their velocities estimated individually. In modeling IPS it is important that the scattering be 'weak' because the model then requires only 1 spatial parameter instead of 3. EISCAT can only operate near 933MHz which limits the observation to outside of 18R · , however the VLBA has higher frequency receivers which allow it to observe inside of 15R · . The density variance δN e 2 in the fast wind is a factor of 10-15 less than in the slow (Coles et al., 1995) making it necessary to consider the entire line of sight, particularly when the fast wind occupies the center portion. Using the point of closest approach and the average velocity to characterize the observation can lead to an incorrect interpretation of the data. We have compared our IPS observations with maps made from the Yohkoh soft X ray, HAO's white-light electron density, and Stanford magnetic field measurements as well as with the IMP8 and Ulysses spacecraft data to assist in placing the fast and slow wind. Here we have selected those observation from 1994 which were dominated by the southern coronal hole and have estimated a velocity acceleration profile for the fast solar wind between 7 and 100R · which is presented in Figure 1. The observations suggest that the fast solar wind is fully developed by ≅7R

  13. Perturbation of the solar wind in a model terrestrial foreshock

    International Nuclear Information System (INIS)

    Skadron, G.; Holdaway, R.D.; Scholer, M.

    1986-01-01

    We analyze the perturbation of the solar wind in the earth's foreshock. The foreshock is modulated as a planar magnetic flux tube having a 15 R/sub E/ half width. Within the flux tube the upstream energetic particle pressure is assumed to fall monotonically to zero at the flux tube boundary and decline in the upstream direction with a scale length of 8 R/sub E/. The incident solar wind is assumed to flow uniformly with a velocity of 400 km s -1 , a density of 8 cm -3 , a pressure of 50 eV cm -3 , and a magnetic field of 4γ directed parallel to the flow. The solar wind density, velocity, and magnetic field within the foreshock are described by the steady state ideal MHD equations. We find that (1) the vector solar wind velocity perturbation rotates from the sunward to the transverse direction with increasing distance from the axis of the flux tube, (2) the peak solar wind deflection is located --3R/sub E/ within the flux tube boundary, (3) a central upstream pressure of 200 eV cm -3 produces a maxium deceleration of 6 km s -1 and a maximum deflection of 1.3 0 , (4) a central upstream pressure of 600 eV cm -3 produces a maximum deceleration of 19 km s -1 and a maximum deflection of 3.6 0 , and (5) the deflection and deceleration are accompanied by perturbations of the solar wind density and magnetic field. These perturbations are largest near the flux tube boundary where both form spikes having a width of --2R/sub E/. For a 600 eV cm -3 central pressure those spikes have amplitudes of 2 cm -3 and lγ, respectively. We have analyzed the linearized flow problem analytically and reduced the solutions to quadrature. These solutions are found to be good approximations to the numerical nonlinear solutions for moderate values of the upstream particle pressure

  14. Implementation Strategy for a Global Solar and Wind Atlas

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-01-15

    In July 2009, Major Economies Forum leaders met to prepare for the COP 15 Copenhagen Conference that took place later that year. At this occasion the Major Economies Forum Global Partnership f or low carbon and climate-friendly technology was founded and Technology Action Plans (TAPs) for ten key low-carbon technologies were drafted. At that juncture Denmark, Germany and Spain took on the responsibility for drafting TAPs for Solar and Wind Energy Technologies. The TAPs were then consolidated and presented at COP 15 that would later take place in December in Copenhagen. Since then, countries that led the development of the Action Plans have started their implementation. During a first Clean Energy Ministerial (CEM) in July 2010 in Washington on the invitation of Steven Chu, US Secretary of Energy, several initiatives were launched. Denmark, Germany and Spain took the lead in the implementation of the TAPs for Solar and Wind Technologies and initiated the Multilateral Working Group on Solar and Wind Energy Technologies (MWGSW). Several countries joined the working group in Washington and afterwards. In two international workshops in Bonn (June 2010) and Madrid (November 2010) and in meetings during the first CEM in Washington (July 2010) and the second CEM in Abu Dhabi (April 2011) the Multilateral Working Group made substantial progress in the two initial fields of action: (1) the Development of a Global Solar and Wind Atlas; and (2) the Development of a Long-term Strategy on Joint Capacity Building. Discussion papers on the respective topics were elaborated involving the Working Group's member countries as well as various international institutions. This led to concrete proposals for several pilot activities in both fields of action. After further specifying key elements of the suggested projects in two expert workshops in spring 2011, the Multilateral Working Group convened for a third international workshop in Copenhagen, Denmark, to discuss the project

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

    Energy Technology Data Exchange (ETDEWEB)

    Khabarova, Olga V.; Obridko, Vladimir N.; Kharshiladze, Alexander F. [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Moscow (Russian Federation); Malova, Helmi V. [Scobeltsyn Nuclear Physics Institute of Lomonosov Moscow State University, Moscow (Russian Federation); Kislov, Roman A.; Zelenyi, Lev M. [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Warsaw (Poland); Tokumaru, Munetoshi; Fujiki, Ken’ichi [Institute for Space-Earth Environmental Research, Nagoya University (Japan); Sokół, Justyna M.; Grzedzielski, Stan [Space Research Centre of the Polish Academy of Sciences (CBK), Warsaw (Poland)

    2017-02-10

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

  16. The genesis solar-wind sample return mission

    International Nuclear Information System (INIS)

    Wiens, Roger C.

    2009-01-01

    The compositions of the Earth's crust and mantle, and those of the Moon and Mars, are relatively well known both isotopically and elementally. The same is true of our knowledge of the asteroid belt composition, based on meteorite analyses. Remote measurements of Venus, the Jovian atmosphere, and the outer planet moons, have provided some estimates of their compositions. The Sun constitutes a large majority, > 99%, of all the matter in the solar system. The elemental composition of the photosphere, the visible 'surface' of the Sun, is constrained by absorption lines produced by particles above the surface. Abundances for many elements are reported to the ±10 or 20% accuracy level. However, the abundances of other important elements, such as neon, cannot be determined in this way due to a relative lack of atomic states at low excitation energies. Additionally and most importantly, the isotopic composition of the Sun cannot be determined astronomically except for a few species which form molecules above sunspots, and estimates derived from these sources lack the accuracy desired for comparison with meteoritic and planetary surface samples measured on the Earth. The solar wind spreads a sample of solar particles throughout the heliosphere, though the sample is very rarified: collecting a nanogram of oxygen, the third most abundant element, in a square centimeter cross section at the Earth's distance from the Sun takes five years. Nevertheless, foil collectors exposed to the solar wind for periods of hours on the surface of the Moon during the Apollo missions were used to determine the helium and neon solar-wind compositions sufficiently to show that the Earth's atmospheric neon was significantly evolved relative to the Sun. Spacecraft instruments developed subsequently have provided many insights into the composition of the solar wind, mostly in terms of elemental composition. These instruments have the advantage of observing a number of parameters simultaneously

  17. Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora

    Science.gov (United States)

    Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R.

    2011-01-01

    The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods

  18. Self consistent MHD modeling of the solar wind from coronal holes with distinct geometries

    Science.gov (United States)

    Stewart, G. A.; Bravo, S.

    1995-01-01

    Utilizing an iterative scheme, a self-consistent axisymmetric MHD model for the solar wind has been developed. We use this model to evaluate the properties of the solar wind issuing from the open polar coronal hole regions of the Sun, during solar minimum. We explore the variation of solar wind parameters across the extent of the hole and we investigate how these variations are affected by the geometry of the hole and the strength of the field at the coronal base.

  19. Predicting Ionization Rates from SEP and Solar Wind Proton Precipitation into the Martian Atmosphere

    Science.gov (United States)

    Jolitz, R.; Dong, C.; Lee, C. O.; Curry, S.; Lillis, R. J.; Brain, D.; Halekas, J. S.; Larson, D. E.; Bougher, S. W.; Jakosky, B. M.

    2017-12-01

    Precipitating energetic particles ionize planetary atmospheres and increase total electron content. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutrals and pass through the magnetosheath, while SEPs are sufficiently energetic to cross the magnetosheath unchanged. In this study we will present predicted ionization rates and resulting electron densities produced by solar wind and SEP proton ionization during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare ionization by SEP and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help to quantify how the ionosphere responds to extreme solar events during solar minimum.

  20. MHD effects of the solar wind flow around planets

    Directory of Open Access Journals (Sweden)

    H. K. Biernat

    2000-01-01

    Full Text Available The study of the interaction of the solar wind with magnetized and unmagnetized planets forms a central topic of space research. Focussing on planetary magnetosheaths, we review some major developments in this field. Magnetosheath structures depend crucially on the orientation of the interplanetary magnetic field, the solar wind Alfvén Mach number, the shape of the obstacle (axisymmetric/non-axisymmetric, etc., the boundary conditions at the magnetopause (low/high magnetic shear, and the degree of thermal anisotropy of the plasma. We illustrate the cases of Earth, Jupiter and Venus. The terrestrial magnetosphere is axisymmetric and has been probed in-situ by many spacecraft. Jupiter's magnetosphere is highly non-axisymmetric. Furthermore, we study magnetohydrodynamic effects in the Venus magnetosheath.

  1. Spacecraft observations of solar wind turbulence: an overview

    International Nuclear Information System (INIS)

    Horbury, T S; Forman, M A; Oughton, S

    2005-01-01

    Spacecraft measurements in the solar wind offer the opportunity to study magnetohydrodynamic (MHD) turbulence in a collisionless plasma in great detail. We review some of the key results of the study of this medium: the presence of large amplitude Alfven waves propagating predominantly away from the Sun; the existence of an active turbulent cascade; and the presence of intermittency similar to that in neutral fluids. We also discuss the presence of anisotropy in wavevector space relative to the local magnetic field direction. Some models suggest that MHD turbulence can evolve to a state with power predominantly in wavevectors either parallel to the magnetic field ('slab' fluctuations) or approximately perpendicular to it ('2D'). We review the existing evidence for such anisotropy, which has important consequences for the transport of energetic particles. Finally, we present the first results of a new analysis which provides the most accurate measurements to date of the wave-vector anisotropy of wavevector power in solar wind MHD turbulence

  2. Solar wind acceleration in a prescribed flow geometry

    International Nuclear Information System (INIS)

    Biernat, H.; Koemle, N.; Lichtenegger, H.

    1985-01-01

    It is known that the flow tubes above coronal holes diverge stronger than radial and that the magnetic field lines may be considerably curved near the border of the holes. The authors investigate the consequences of such a magnetic field geometry on the flow of the solar wind plasma in the vicinity of the Sun. For this purpose the one-dimensional conservation equations are solved along prescribed flow tubes. A temperature profile based on observational data (EUV rocket-observations) is used in the calculations. In an alternative approach the temperature is determined by a polytropic index, which is assumed to be variable. The authors study how both curvature and non-radial divergence of the flow tubes modify the velocity, the density, and the energy balance of the solar wind plasma. (Auth.)

  3. On the penetration of solar wind inhomogeneities into the magnetosphere

    International Nuclear Information System (INIS)

    Maksimov, V.P.; Senatorov, V.N.

    1980-01-01

    Laboratory experiments were used as a basis to study the process of interaction between solar wind inhomogeneities and the Earth's magnetosphere. The given inhomogeneity represents a lump of plasma characterized by an increased concentration of particles (nsub(e) approximately 20-30 cm -3 ), a discrete form (characteristic dimensions of the lump are inferior to the magnetosphere diameter) and the velocity v approximately 350 km/s. It is shown that there is the possibility of penetration of solar wind inhomogeneities inside the Earth's magnetosphere because of the appearance in the inhomogeneity of an electric field of transverse polarization. The said process is a possible mechanism of the formation of the magnetopshere entrance layer

  4. Control of particle precipitation by energy transfer from solar wind

    Science.gov (United States)

    Bremer, J.; Gernandt, H.

    1985-12-01

    The energy transfer function (epsilon), introduced by Perreault and Akasofu (1978), appears to be well suited for the description of the long-term control of the particle precipitation by interplanetary parameters. An investigation was conducted with the objective to test this control in more detail. This investigation included the calculation of hourly epsilon values on the basis of satellite-measured solar wind and IMF (interplanetary magnetic field) data. The results were compared with corresponding geomagnetic and ionospheric data. The ionospheric data had been obtained by three GDR (German Democratic Republic) teams during the 21st, 22nd, and 23rd Soviet Antarctic Expeditions in the time period from 1976 to 1979. It was found that, in high latitudes, the properties of the solar wind exercise a pronounced degree of control on the precipitation of energetic particles into the atmosphere, taking into account a time delay of about one hour due to the occurrence of magnetospheric storage processes.

  5. Nearly incompressible MHD turbulence in the solar wind

    International Nuclear Information System (INIS)

    Matthaeus, W.H.; Zhou, Y.

    1989-01-01

    Observational studies indicate that solar wind plasma and magnetic field fluctuations may be meaningfully viewed as an example of magnetohydrodynamic turbulence. This paper presents a brief summary of some relevant results of turbulence theory and reviews a turbulence style description of 'typical' solar wind conditions. Recent results, particularly those regarding the radial evolution of inertial range cross helicity, support the viewpoint that interplanetary turbulence is active and evolving with heliocentric distance. A number of observed properties can be understood by appeal to incompressible turbulence mechanisms. This connection may be understood by appeal to incompressible turbulence mechanisms. This connection may be understood in terms of theories of pseudosound density fluctuations and nearly incompressible magnetohydrodynamics, which are also reviewed here. Finally, we summarize a recent two-scale dynamical theory of the radial and temporal evolution of the turbulence, which may provide an additional framework for understanding the observations. (author). 49 refs

  6. Save with Solar and Wind, Summer 2002 (Newsletter)

    Energy Technology Data Exchange (ETDEWEB)

    2002-07-01

    This newsletter is published by the Department of Energy's Federal Energy Management Program. It is intended for facility managers, contracting officials, energy specialists, and others involved in helping Federal agencies increase their use of cost-effective solar and wind energy systems at their facilities. Renewable energy systems ultimately save agencies money by reducing utility costs; they also help to lower the emissions associated with the use of fossil fuels. This issue describes a new strategy to achieve the Federal goal for renewable energy, as well as some new solar and wind systems installed at facilities of the Department of Defense, the U.S. Geological Survey, the U.S. Postal Service, the National Park Service, and other agencies.

  7. A desalination plant with solar and wind energy

    International Nuclear Information System (INIS)

    Chen, H; Ye, Z; Gao, W

    2013-01-01

    The shortage of freshwater resources has become a worldwide problem. China has a water shortage, although the total amount of water resources is the sixth in the world, the per capita water capacity is the 121th (a quarter of the world's per capita water capacity), and the United Nations considers China one of the poorest 13 countries in the world in terms of water. In order to increase the supply of fresh water, a realistic way is to make full use of China's long and narrow coastline for seawater desalination. This paper discusses a sea water desalination device, the device adopts distillation, uses the greenhouse effect principle and wind power heating principle, and the two-type start is used to solve the problem of vertical axis wind turbine self-starting. Thrust bearings are used to ensure the stability of the device, and to ensure absorbtion of wind energy and solar energy, and to collect evaporation of water to achieve desalination. The device can absorb solar and wind energy instead of input energy, so it can be used in ship, island and many kinds of environment. Due to the comprehensive utilization of wind power and solar power, the efficiency of the device is more than other passive sea water desalting plants, the initial investment and maintenance cost is lower than active sea water desalting plant. The main part of the device cannot only be used in offshore work, but can also be used in deep sea floating work, so the device can utilise deep sea energy. In order to prove the practicability of the device, the author has carried out theory of water production calculations. According to the principle of conservation of energy, the device ais bsorbing solar and wind power, except loose lost part which is used for water temperature rise and phase transition. Assume the inflow water temperature is 20 °C, outflow water temperature is 70 °C, the energy utilization is 60%, we can know that the water production quantity is 8 kg/ m 2 per hour. Comparing

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

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2009-02-01

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

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

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2009-02-01

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

  10. Magnetic dips in the solar wind

    International Nuclear Information System (INIS)

    Dobrowolny, M.; Bavassano, B.; Mariani, F.; Ness, N.; Burlaga, L.

    1978-09-01

    With the help of magnetic data from the HELIOS 1 fluxgate magnetometer, with a 0.2 sec resolution, the structures of several interplanetary discontinuities involving magnetic dips and rotations of the magnetic field vector were investigated. A minimum variance analysis illustrates the behavior of the magnetic field through the transition in the plane of its maximum variation. By means of this analysis, quite different structures have been individuated, in particular, narrow transitions resembling almost one-dimensional reconnected neutral sheets. For the thinner cases (scale lengths of the magnetic rotation of the order or smaller than 1,000 km), results show the observed structures could be the nonlinear effect of a resistive tearing mode instability having developed on an originally one-dimensional neutral sheet at the solar corona

  11. Mars, solar wind, and supernova - implications of the Viking data

    International Nuclear Information System (INIS)

    Shimizu, M.

    1977-01-01

    A scenario for the evolution of the Martian atmosphere consistent with various data of the Viking 1 and 2 and the Mariner 9 has been presented: Mars was formed from Renazzo-type meteorites polluted by the products of supernova explosion. A dense ancient Martian atmosphere has been swept away by the solar wind and the present tenuous atmosphere was supplied recently by the volcanic gas from the Tharsis region, after the occurrence of the magnetic field. (Auth.)

  12. Electron temperature anisotropy constraints in the solar wind

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Trávníček, Pavel M.; Maksimovic, M.; Marsch, E.; Fazakerley, A.; Scime, E. E.

    2008-01-01

    Roč. 113, A3 /2008/ (2008), A03103/1-A03103/10 ISSN 0148-0227 R&D Projects: GA AV ČR IAA300420602 Grant - others:EU(XE) ESA-PECS project No. 98024 Institutional research plan: CEZ:AV0Z10030501; CEZ:AV0Z30420517 Keywords : solar wind electrons * temperature anisotropy * radial Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.147, year: 2008

  13. Optimization criteria for solar and wind power systems

    Energy Technology Data Exchange (ETDEWEB)

    Salieva, R B

    1976-01-01

    It is shown that the design of solar and wind power systems requires both the specification of the target function and the optimization of the system with respect to two criteria, namely, the system must be economical (minimum cost to the economy) and it must be reliable (the probability of failure-free operation of the system must be not less than a standard value).

  14. Statistical Properties of Geomagnetic Activity Indices and Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Jung-Hee Kim

    2014-06-01

    Full Text Available As the prediction of geomagnetic storms is becoming an important and practical problem, conditions in the Earth’s magnetosphere have been studied rigorously in terms of those in the interplanetary space. Another approach to space weather forecast is to deal with it as a probabilistic geomagnetic storm forecasting problem. In this study, we carry out detailed statistical analysis of solar wind parameters and geomagnetic indices examining the dependence of the distribution on the solar cycle and annual variations. Our main findings are as follows: (1 The distribution of parameters obtained via the superimposed epoch method follows the Gaussian distribution. (2 When solar activity is at its maximum the mean value of the distribution is shifted to the direction indicating the intense environment. Furthermore, the width of the distribution becomes wider at its maximum than at its minimum so that more extreme case can be expected. (3 The distribution of some certain heliospheric parameters is less sensitive to the phase of the solar cycle and annual variations. (4 The distribution of the eastward component of the interplanetary electric field BV and the solar wind driving function BV2, however, appears to be all dependent on the solar maximum/minimum, the descending/ascending phases of the solar cycle and the equinoxes/solstices. (5 The distribution of the AE index and the Dst index shares statistical features closely with BV and BV2 compared with other heliospheric parameters. In this sense, BV and BV2 are more robust proxies of the geomagnetic storm. We conclude by pointing out that our results allow us to step forward in providing the occurrence probability of geomagnetic storms for space weather and physical modeling.

  15. Theoretical models for MHD turbulence in the solar wind

    International Nuclear Information System (INIS)

    Veltri, P.; Malara, F.

    1997-01-01

    The in situ measurements of velocity, magnetic field, density and temperature fluctuations performed in the solar wind have greatly improved our knowledge of MDH turbulence not only from the point of view of space physics but also from the more general point of view of plasma physics. These fluctuations which extend over a wide range of frequencies (about 5 decades), a fact which seems to be the signature of turbulent nonlinear energy cascade, display, mainly in the trailing edge of high-speed streams, a number of features characteristic of a self-organized situation: i) a high degree of correlation between magnetic and velocity field fluctuations, ii) a very low level of fluctuations in mass density and magnetic-field intensity, iii) a considerable anisotropy revealed by minimum variance analysis of the magnetic-field correlation tensor. Many fundamental processes in plasma physics, which were largely unknown or not understood before their observations in the solar wind, have been explained, by building up analytical models or performing numerical simulations. We discuss the most recent analytical theories and numerical simulations and outline the limits implicit in any analysis which consider the low-frequency solar-wind fluctuations as a superposition of linear modes. The characterization of low-frequency fluctuations during Alfvenic periods, which results from the models discussed, is finally presented

  16. Interaction of the solar wind with comets: a Rosetta perspective.

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-07-13

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the 'singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

  17. Kinetic instabilities in the solar wind: A short review

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, Lorenzo, E-mail: l.matteini@imperial.ac.uk [Imperial College London, London SW7 2AZ (United Kingdom)

    2016-03-25

    We know from in situ measurements that solar wind plasma is far from thermal equilibrium. Distribution functions of its main constituents -electrons, protons, and alpha particles-show several departures from Maxwellian, including temperature anisotropy, relative drifts and secondary populations streaming along the local magnetic field. We present a short review of recent solar wind observations of these non-thermal features and associated signatures of wave-particle interactions. Several kinetic instabilities are expected to be at work in the solar wind during its expansion, playing a role in the continuous shaping of particle distributions with distance, and regulating the macroscopic behavior of the plasma. Over the past years, modeling of these processes by means of numerical simulations has been successful in reproducing and explaining the observations; these include the evolution of the plasma due to radial expansion and the response of individual species to different kinetic instabilities. Finally, the impact of local inhomogeneities, like current sheets and turbulence, on the development of kinetic instabilities is also discussed.

  18. Dynamics of Intense Currents in the Solar Wind

    Science.gov (United States)

    Artemyev, Anton V.; Angelopoulos, Vassilis; Halekas, Jasper S.; Vinogradov, Alexander A.; Vasko, Ivan Y.; Zelenyi, Lev M.

    2018-06-01

    Transient currents in the solar wind are carried by various magnetic field discontinuities that contribute significantly to the magnetic field fluctuation spectrum. Internal instabilities and dynamics of these discontinuities are believed to be responsible for magnetic field energy dissipation and corresponding charged particle acceleration and heating. Accurate modeling of these phenomena requires detailed investigation of transient current formation and evolution. By examining such evolution using a unique data set compiled from observations of the same solar wind flow by two spacecraft at Earth’s and Mars’s orbits, we show that it consists of several processes: discontinuity thinning (decrease in thickness normalized by the ion inertial length), intensification of currents normalized to the proton thermal current (i.e., the product of proton charge, density, and thermal velocity), and increase in the compressional component of magnetic field variations across discontinuities. The significant proton temperature variation around most observed discontinuities indicates possible proton heating. Plasma velocity jumps across the discontinuities are well correlated with Alfvén velocity changes. We discuss possible explanations of the observed discontinuity evolution. We also compare the observed evolution with predictions of models describing discontinuity formation due to Alfvén wave steepening. Our results show that discontinuity modeling likely requires taking into account both the effects of nonlinear Alfvén wave dynamics and solar wind expansion.

  19. On WKB expansions for Alfven waves in the solar wind

    International Nuclear Information System (INIS)

    Hollweg, J.V.

    1990-01-01

    The author reexamines the WKB expansion for toroidal Alfven waves in the solar wind, as described by equations (9) of Heinemann and Olbert (1980). His principal conclusions are as follows: (1) The WKB expansion used by Belcher (1971) and Hollweg (1973) is nonuniformly convergent. (2) Using the method of multiple scales (Nayfeh, 1981), he obtains an expansion which is uniform. (3) The uniform expansion takes into account the small modification to the Alfven wave phase speed due to spatial gradients of the background. (4) Both the uniform and nonuniform expansions reveal that each normal mode has both Elsaesser variables δz + ≠ 0 and δz - ≠ 0. Thus if δz - corresponds to the outgoing mode in a homogeneous background, an observation of δz + ≠ 0 does not necessarily imply the presence of the inward propagating mode, as is commonly assumed. (5) Even at the Alfven critical point (where V = υ A ) he finds that δz + ≠ 0. Thus incompressible MHD turbulence, which requires both δz + ≠ 0 and δz - ≠ 0, can proceed at the Alfven critical point (cf. Roberts, 1989). (6) With very few exceptions, the predictions of these calculations do not agree with recent observations (Marsch and Tu, 1990) of the power spectra of δz + and δz - in the solar wind. Thus the evolution of Alfven waves in the solar wind is governed by dynamics not included in the Heinemann and Olbert equations

  20. Construction of Solar-Wind-Like Magnetic Fields

    Science.gov (United States)

    Roberts, Dana Aaron

    2012-01-01

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the\\random character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (discontinuities), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

  1. Solar wind heavy ions from energetic coronal events

    International Nuclear Information System (INIS)

    Bame, S.J.

    1978-01-01

    Ions heavier than those of He can be resolved in the solar wind with electrostatic E/q analyzers when the local thermal temperatures are low. Ordinarily this condition prevails in the low speed solar wind found between high speed streams, i.e. the interstream, IS, solar wind. Various ions of O, Si and Fe are resolved in IS heavy ion spectra. Relative ion peak intensities indicate that the O ionization state is established in the IS coronal source regions at approx. 2.1 x 10 6 K while the state of Fe is frozen in at approx. 1.5 x 10 6 K farther out. Occasionally, anomalous spectra are observed in which the usually third most prominent ion peak, O 8+ , is depressed as are the Fe peaks ranging from Fe 12+ to Fe 7+ . A prominent peak in the usual Si 8+ position of IS spectra is self-consistently shown to be Fe 16+ . These features demonstrate that the ionization states were frozen in at higher than usual coronal temperatures. The source regions of these hot heavy ion spectra are identified as energetic coronal events including flares and nonflare coronal mass ejections. 24 references

  2. Analysis of the solar/wind resources in Southern Spain for optimal sizing of hybrid solar-wind power generation systems

    Science.gov (United States)

    Quesada-Ruiz, S.; Pozo-Vazquez, D.; Santos-Alamillos, F. J.; Lara-Fanego, V.; Ruiz-Arias, J. A.; Tovar-Pescador, J.

    2010-09-01

    A drawback common to the solar and wind energy systems is their unpredictable nature and dependence on weather and climate on a wide range of time scales. In addition, the variation of the energy output may not match with the time distribution of the load demand. This can partially be solved by the use of batteries for energy storage in stand-alone systems. The problem caused by the variable nature of the solar and wind resources can be partially overcome by the use of energy systems that uses both renewable resources in a combined manner, that is, hybrid wind-solar systems. Since both resources can show complementary characteristics in certain location, the independent use of solar or wind systems results in considerable over sizing of the batteries system compared to the use of hybrid solar-wind systems. Nevertheless, to the day, there is no single recognized method for properly sizing these hybrid wind-solar systems. In this work, we present a method for sizing wind-solar hybrid systems in southern Spain. The method is based on the analysis of the wind and solar resources on daily scale, particularly, its temporal complementary characteristics. The method aims to minimize the size of the energy storage systems, trying to provide the most reliable supply.

  3. Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

    Directory of Open Access Journals (Sweden)

    J.-S. Wang

    2004-06-01

    Full Text Available Electron density profiles in the Martian ionosphere observed by the radio occultation experiment on board Mars Global Surveyor have been analyzed to determine if the densities are influenced by the solar wind. Evidence is presented that the altitude of the maximum ionospheric electron density shows a positive correlation to the energetic proton flux in the solar wind. The solar wind modulation of the Martian ionosphere can be attributed to heating of the neutral atmosphere by the solar wind energetic proton precipitation. The modulation is observed to be most prominent at high solar zenith angles. It is argued that this is consistent with the proposed modulation mechanism.

  4. Analysis of off-grid hybrid wind turbine/solar PV water pumping systems

    Science.gov (United States)

    While many remote water pumping systems exist (e.g. mechanical windmills, solar photovoltaic , wind-electric, diesel powered), very few combine both the wind and solar energy resources to possibly improve the reliability and the performance of the system. In this paper, off-grid wind turbine (WT) a...

  5. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, J.; Gaelzer, R. [UFPEL, Pelotas (Brazil); Vinas, A. F. [NASA GSFC, Greenbelt, MD 20771 (United States); Yoon, P. H. [IPST, UMD, College Park, MD (United States); Ziebell, L. F., E-mail: joel.pavan@ufpel.edu.br, E-mail: rudi@ufpel.edu.br, E-mail: adolfo.vinas@nasa.gov, E-mail: yoonp@umd.edu, E-mail: luiz.ziebell@ufrgs.br [UFRGS, Porto Alegre (Brazil)

    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.

  6. Cometary X-rays : solar wind charge exchange in cometary atmospheres

    NARCIS (Netherlands)

    Bodewits, Dennis

    2007-01-01

    The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

  7. Solar cycle variation of cosmic ray intensity along with interplanetary and solar wind plasma parameters

    International Nuclear Information System (INIS)

    Mishra, R.K.; Tiwari, S.; Agarwal, R.

    2008-01-01

    Galactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V , B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V , B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23. (Authors)

  8. Estimation of wind and solar resources in Mali

    Energy Technology Data Exchange (ETDEWEB)

    Badger, J.; Kamissoko, F.; Olander Rasmussen, M.; Larsen, Soeren; Guidon, N.; Boye Hansen, L.; Dewilde, L.; Alhousseini, M.; Noergaard, P.; Nygaard, I.

    2012-11-15

    The wind resource has been estimated for all of Mali at 7.5 km resolution using the KAMM/WAsP numerical wind atlas methodology. Three domains were used to cover entire country and three sets of wind classes used to capture change in large scale forcing over country. The final output includes generalized climate statistics for any location in Mali, giving wind direction and wind speed distribution. The modelled generalized climate statistics can be used directly in the WAsP software. The preliminary results show a wind resource, which is relatively low, but which under certain conditions may be economically feasible, i.e. at favourably exposed sites, giving enhanced winds, and where practical utilization is possible, given consideration to grid connection or replacement or augmentation of diesel-based electricity systems. The solar energy resource for Mali was assessed for the period between July 2008 and June 2011 using a remote sensing based estimate of the down-welling surface shortwave flux. The remote sensing estimates were adjusted on a month-by-month basis to account for seasonal differences between the remote sensing estimates and in situ data. Calibration was found to improve the coefficient of determination as well as decreasing the mean error both for the calibration and validation data. Compared to the results presented in the ''Renewable energy resources in Mali - preliminary mapping''-report that showed a tendency for underestimation compared to data from the NASA PPOWER/SSE database, the presented results show a very good agreement with the in situ data (after calibration) with no significant bias. Unfortunately, the NASA-database only contains data up until 2005, so a similar comparison could not be done for the time period analyzed in this study, although the agreement with the historic NASA data is still useful as reference. (LN)

  9. The influence of solar wind variability on magnetospheric ULF wave power

    International Nuclear Information System (INIS)

    Pokhotelov, D.; Rae, I.J.; Mann, I.R.

    2015-01-01

    Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

  10. ON THE NATURE OF THE SOLAR WIND FROM CORONAL PSEUDOSTREAMERS

    International Nuclear Information System (INIS)

    Wang, Y.-M.; Sheeley, N. R. J.R.; Grappin, R.; Robbrecht, E.

    2012-01-01

    Coronal pseudostreamers, which separate like-polarity coronal holes, do not have current sheet extensions, unlike the familiar helmet streamers that separate opposite-polarity holes. Both types of streamers taper into narrow plasma sheets that are maintained by continual interchange reconnection with the adjacent open magnetic field lines. White-light observations show that pseudostreamers do not emit plasma blobs; this important difference from helmet streamers is due to the convergence of like-polarity field lines above the X-point, which prevents the underlying loops from expanding outward and pinching off. The main component of the pseudostreamer wind has the form of steady outflow along the open field lines rooted just inside the boundaries of the adjacent coronal holes. These flux tubes are characterized by very rapid expansion below the X-point, followed by reconvergence at greater heights. Analysis of an idealized pseudostreamer configuration shows that, as the separation between the underlying holes increases, the X-point rises and the expansion factor f ss at the source surface increases. In situ observations of pseudostreamer crossings indicate wind speeds v ranging from ∼350 to ∼550 km s –1 , with O 7+ /O 6+ ratios that are enhanced compared with those in high-speed streams but substantially lower than in the slow solar wind. Hydrodynamic energy-balance models show that the empirical v-f ss relation overestimates the wind speeds from nonmonotonically expanding flux tubes, particularly when the X-point is located at low heights and f ss is small. We conclude that pseudostreamers produce a 'hybrid' type of outflow that is intermediate between classical slow and fast solar wind.

  11. Relationship between velocity gradients and magnetic turbulence in the solar wind

    International Nuclear Information System (INIS)

    Garrett, H.B.

    1974-01-01

    The correlations among the time derivative of the solar-wind velocity, the magnitude of the interplanetary magnetic field (IMF), and the IMF turbulence level are examined to test the idea that interaction between two colliding solar-wind streams can generate turbulence in the solar wind and the IMF. Data obtained by Explorer 33 on the solar wind and IMF are described, and the analysis techniques are outlined. The results indicate that the IMF turbulence level, as measured by the variance, is correlated with the existence of positive velocity gradients in the solar wind. It is noted that while the variance is an increasing function of the field magnitude, it is also independently correlated with the solar-wind velocity gradient

  12. Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel; Kasper, J. C.; Lazarus, A. J.

    2006-01-01

    Roč. 33, č. 9 (2006), L09101/1-L09101/4 ISSN 0094-8276 R&D Projects: GA AV ČR(CZ) IAA3042403 Grant - others:ESA(XE) PECS 98024; NASA (US) NAG-10915 Institutional research plan: CEZ:AV0Z30420517 Keywords : proton temperature anisotropy * solar wind * in situ observations Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.602, year: 2006

  13. Anisotropic Behaviour of Magnetic Power Spectra in Solar Wind Turbulence.

    Science.gov (United States)

    Banerjee, S.; Saur, J.; Gerick, F.; von Papen, M.

    2017-12-01

    Introduction:High altitude fast solar wind turbulence (SWT) shows different spectral properties as a function of the angle between the flow direction and the scale dependent mean magnetic field (Horbury et al., PRL, 2008). The average magnetic power contained in the near perpendicular direction (80º-90º) was found to be approximately 5 times larger than the average power in the parallel direction (0º- 10º). In addition, the parallel power spectra was found to give a steeper (-2) power law than the perpendicular power spectral density (PSD) which followed a near Kolmogorov slope (-5/3). Similar anisotropic behaviour has also been observed (Chen et al., MNRAS, 2011) for slow solar wind (SSW), but using a different method exploiting multi-spacecraft data of Cluster. Purpose:In the current study, using Ulysses data, we investigate (i) the anisotropic behaviour of near ecliptic slow solar wind using the same methodology (described below) as that of Horbury et al. (2008) and (ii) the dependence of the anisotropic behaviour of SWT as a function of the heliospheric latitude.Method:We apply the wavelet method to calculate the turbulent power spectra of the magnetic field fluctuations parallel and perpendicular to the local mean magnetic field (LMF). According to Horbury et al., LMF for a given scale (or size) is obtained using an envelope of the envelope of that size. Results:(i) SSW intervals always show near -5/3 perpendicular spectra. Unlike the fast solar wind (FSW) intervals, for SSW, we often find intervals where power parallel to the mean field is not observed. For a few intervals with sufficient power in parallel direction, slow wind turbulence also exhibit -2 parallel spectra similar to FSW.(ii) The behaviours of parallel and perpendicular power spectra are found to be independent of the heliospheric latitude. Conclusion:In the current study we do not find significant influence of the heliospheric latitude on the spectral slopes of parallel and perpendicular

  14. Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003

    Energy Technology Data Exchange (ETDEWEB)

    Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.

    2008-05-01

    Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.

  15. Voyager microwave scintillation measurements of solar wind plasma parameters

    International Nuclear Information System (INIS)

    Martin, J.M.

    1985-01-01

    During the solar conjunctions of Voyager 1 and 2 spacecraft in August 1979, September 1980, and November 1982, temporal variations of intensity and frequency of the dual-wavelength (3.6 and 13 cm) radio transmissions from the spacecraft were observed and subsequently analyzed to infer characteristics of the solar wind plasma flow. Measurements of the temporal wave structure function were used to estimate the spectral index of the power law spatial spectrum of irregularities. Theoretical-intensity scintillation spectra were compared with measured intensity spectra to obtain least-squares estimates of (1) mean velocity, (2) random velocity, (3) axial ratio, and (4) electron density standard deviation. Uncertainties in parameter estimates were calculated by standard propagation of errors techniques. Mean velocity and electron density standard deviations in 1979-1980 show little dependence on solar latitude. Density standard deviation estimates were 3-10% of the background mean density and mean velocity estimates ranged from approx.200 km/s inside 17 solar radii to approx.300 km/s at 25 solar radii. 1982 density standard deviation estimates increased rapidly with latitude near 45 0 N, then sharply decreased north of that latitude, indicating the existence of a polar region of reduced fluctuations surrounded by a thin cone of strong density irregularities

  16. Intercalibration and Cross-Correlation of Ace and Wind Solar Wind Data

    Science.gov (United States)

    2003-01-01

    This report covers activities funded from October 1, 1998 through September 30, 2002. Two yearly status reports have been filed on this grant, and they are included as Appendix 1. The purpose of this grant was to compare ACE and Wind solar wind parameters when the two spacecraft were near to one another and then to use the intercalibrated parameters to carry out scientific investigations. In September, 2001 a request for a one-year, no-cost extension until September 30, 2002 was submitted and approved. The statement of work for that extension included adjustment of ACE densities below wind speeds of 350 km/s, a study of shock normal orientations using travel time delays between the two spacecraft, comparison of density jumps at shocks, and a study of temperature anisotropies and double streaming to see if such features evolved between the spacecraft.

  17. A study on evaluating the power generation of solar-wind hybrid systems in Izmir, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Ulgen, K. [Ege Univ., Solar Energy Inst., Izmir (Turkey); Hepbasli, A. [Ege Univ., Dept. of Mechanical Engineering, Izmir (Turkey)

    2003-03-15

    Turkey is abundant in terms of renewable energy resources. Residential and industrial utilization of solar energy started in the 1980s, while the first Build-Operate-Transfer (BOT) windmill park, located at Alacati, Izmir, was commissioned in 1998. Additionally, power generation through solar-wind hybrid systems has recently appeared on the Turkish market. This study investigates the wind and solar thermal power availability in Izmir, located in the western part of Turkey. Simple models were developed to determine wind, solar, and hybrid power resources per unit area. Experimental data, consisting of hourly records over a 5 yr period, 1995-1999, were measured in the Solar/Wind Meteorological Station of the Solar Energy Institute at Ege University. Correlations between solar and wind power data were carried out on an hourly, a daily, and a monthly basis. It can be concluded that possible applications of hybrid systems could be considered for the efficient utilization of these resources. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; McComas, D. J. [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States); Pogorelov, N. V. [Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2013-05-10

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

  19. Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.

    Science.gov (United States)

    Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M

    2014-06-01

    Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme. Solar wind models must be downscaled in order to drive magnetospheric models Ensemble downscaling is more effective than deterministic downscaling The magnetosphere responds nonlinearly to small-scale solar wind fluctuations.

  20. Investigating the Correlation Between Wind and Solar Power Forecast Errors in the Western Interconnection: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.; Hodge, B. M.; Florita, A.

    2013-05-01

    Wind and solar power generations differ from conventional energy generation because of the variable and uncertain nature of their power output. This variability and uncertainty can have significant impacts on grid operations. Thus, short-term forecasting of wind and solar generation is uniquely helpful for power system operations to balance supply and demand in an electricity system. This paper investigates the correlation between wind and solar power forecasting errors.

  1. Application of Power Systems Economics to Wind and Solar Power Integration

    OpenAIRE

    Mills, Andrew David

    2015-01-01

    The focus of this dissertation is the economic implications of the technical challenges of integrating variable generation, namely wind and solar, into the electric power system. The research is organized around three topics: short-term variability of wind and solar generation, changes in the economic value of wind and solar with increasing penetration, and the effectiveness of different measures at mitigating changes in economic value with increasing penetration levels. Early studies of PV g...

  2. The Solar Wind from Pseudostreamers and their Environs: Opportunities for Observations with Parker Solar Probe and Solar Orbiter

    Science.gov (United States)

    Panasenco, O.; Velli, M.; Panasenco, A.; Lionello, R.

    2017-12-01

    The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Mid-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of pseudostreamers shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at thepseudostreamer base low in the corona. We review and model possible coronal magnetic configurations and solar wind plasma properties at different distances from the solar surface that

  3. Solar and wind energy utilization at Sarawak Southern national parks

    International Nuclear Information System (INIS)

    Abdul Rahman, N.; Kolot, A.

    2006-01-01

    The intentions of renewable energy utilization in Sarawak national parks were to reduce the environmental impacts to the protected surrounding and to overcome fuel transportation problem, as most national parks in Sarawak are not viable for the state electricity grid connection. The study was conducted at three national parks in southern Sarawak; viz. Samusan, Tanjung Datu and Pulau Talang-Talang Besar National Park. The study focused on the effectiveness of the system implementation, energy load and associated problems. Both Samusan and Tanjung Datu National systems are hybrids, which consist of solar photovoltaic panels, wind turbine and diesel generators, whereas, Pulau Talang-Talang Besar National Park is a stand alone system of solar photovoltaic panels only. In addition, the inefficient energy usage was observed at Samusan National Park. The study have identified that lack of local expertise, spare parts availability, transportation and inefficient energy management as the major problems associated to the solar and wind energy system in all national parks studied. Albeit the problems mentioned, the study discovered that the systems were acceptably reliable and satisfactorily supply fraction of the energy requirements to the national parks communities

  4. Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

    International Nuclear Information System (INIS)

    Verma, P L; Singh, Puspraj; Singh, Preetam

    2014-01-01

    Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

  5. Solar wind fluctuations at large scale - A comparison between low and high solar activity conditions

    Science.gov (United States)

    Bavassano, B.; Bruno, R.

    1991-02-01

    The influence of the sun's activity cycle on the solar wind fluctuations at time scales from 1 hour to 3 days in the inner heliosphere (0.3 to 1 AU) is investigated. Hourly averages of plasma and magnetic field data by Helios spacecraft are used. Since fluctuations behave quite differently with changing scale, the analysis is performed separately for two different ranges in time scale. Between 1 and 6 hours Alfvenic fluctuations and pressure-balanced structures are extensively observed. At low solar activity and close to 0.3 AU Alfvenic fluctuations are more frequent than pressure-balanced structures. This predominance, however, weakens for rising solar activity and radial distance, to the point that a role-exchange, in terms of occurrence rate, is found at the maximum of the cycle close to 1 AU. On the other hand, in all cases Alfvenic fluctuations have a larger amplitude than pressure-balanced structures. The Alfvenic contribution to the solar wind energy spectrum comes out to be dominant at all solar activity conditions. These findings support the conclusion that the solar cycle evolution of the large-scale velocity pattern is the factor governing the observed variations.

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

    Science.gov (United States)

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

    2015-04-01

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

  7. The AMPTE program's contribution to studies of the solar wind-magnetosphere-ionosphere interaction

    International Nuclear Information System (INIS)

    Sibeck, D.G.

    1990-01-01

    The Active Magnetospheric Particle Tracer Explorers (AMPTE) program provided important information on the behavior of clouds of plasma artificially injected into the solar wind and the earth's magnetosphere. Now that the releases are over, data from the satellites are being analyzed to investigate the processes by which the ambient solar wind mass, momentum, and energy are transferred to the magnetosphere. Work in progress at APL indicates that the solar wind is much more inhomogeneous than previously believed, that the solar wind constantly buffets the magnetosphere, and that ground observers may remotely sense these interactions as geomagnetic pulsations. 8 refs

  8. Global solar magetic field organization in the extended corona: influence on the solar wind speed and density over the cycle.

    Science.gov (United States)

    Réville, V.; Velli, M.; Brun, S.

    2017-12-01

    The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11yr solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 Rȯ, the source surface radius which approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface: we demonstrate this using 3D global MHD simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). For models to comply with the constraints provided by observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun (Ulysses observations beyond 1 AU), and that the terminal wind speed is anti-correlated with the mass flux, they must accurately describe expansion beyond the solar wind critical point (even up to 10Rȯ and higher in our model). We also show that near activity minimum, expansion in the higher corona beyond 2.5 Rȯ is actually the dominant process affecting the wind speed. We discuss the consequences of this result on the necessary acceleration profile of the solar wind, the location of the sonic point and of the energy deposition by Alfvén waves.

  9. Coupled Solar Wind-Magnetosphere-Ionosphere-Thermosphere System by QFT

    Science.gov (United States)

    Chen, Shao-Guang

    shoot to Sun from the center of Galaxy. The dynamic balance of forces on the solar surface plasma at once is broken and the plasma will upwards eject as the solar wind with redundant negative charge, at the same time, the solar surface remain a cavity as a sunspot whorl with the positive electric potential relative to around. The whorl caused by that the reaction of plasma eject front and upwards with the different velocity at different latitude of solar rotation, leads to the cavity around in the downwards and backwards helix movement. The solar rotation more slow, when the cavity is filled by around plasma in the reverse turn direction, the Jupiter at front had been produced a new cavity, so that we had observe the sunspot pair with different whorl directions and different magnetic polarity. Jupiter possess half mass of all planets in solar system, its action to stop net nuν _{0} flux is primary, so that Jupiter’s period of 11.8 sidereal years accord basically with the period of sunspot eruptions. The solar wind is essentially the plasma with additional electrons flux ejected from the solar surface: its additional electrons come from the ionosphere again eject into the ionosphere and leads to the direct connect between the solar wind and the ionosphere; its magnetism from its redundant negative charge and leads to the connect between the solar wind and the magnetosphere; it possess the high temperature of the solar surface and ejecting kinetic energy leads to the thermo-exchange connect between the solar wind and the thermosphere. Through the solar wind ejecting into and cross over the outside atmosphere carry out the electromagnetic, particles material and thermal exchanges, the Coupled Solar Wind-Magnetosphere-Ionosphere-Thermosphere System to be came into being. This conclusion is inferred only by QFT.

  10. 78 FR 77447 - California Wind Energy Association, First Solar, Inc. v. California Independent System Operator...

    Science.gov (United States)

    2013-12-23

    ... Energy Association, First Solar, Inc. v. California Independent System Operator Corporation, Southern...), California Wind Energy Association and First Solar, Inc. (collectively, Complainants) filed a formal complaint against the California Independent System Operator Corporation (CAISO) and Southern California...

  11. Line Ratios for Solar Wind Charge Exchange with Comets

    Energy Technology Data Exchange (ETDEWEB)

    Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Shelton, R. L.; Stancil, P. C. [Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, GA 30602 (United States); Gu, L.; Kaastra, J., E-mail: pmullen2@illinois.edu [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands)

    2017-07-20

    Charge exchange (CX) has emerged in X-ray emission modeling as a significant process that must be considered in many astrophysical environments—particularly comets. Comets host an interaction between solar wind ions and cometary neutrals to promote solar wind charge exchange (SWCX). X-ray observatories provide astronomers and astrophysicists with data for many X-ray emitting comets that are impossible to accurately model without reliable CX data. Here, we utilize a streamlined set of computer programs that incorporate the multi-channel Landau–Zener theory and a cascade model for X-ray emission to generate cross sections and X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent bare and H-like ions of C, N, O, Ne, Na, Mg, Al, and Si and the cometary neutrals H{sub 2}O, CO, CO{sub 2}, OH, and O. To exemplify the application of this data, we model the X-ray emission of Comet C/2000 WM1 (linear) using the CX package in SPEX and find excellent agreement with observations made with the XMM-Newton RGS detector. Our analyses show that the X-ray intensity is dominated by SWCX with H, while H{sub 2}O plays a secondary role. This is the first time, to our knowledge, that CX cross sections have been implemented into a X-ray spectral fitting package to determine the H to H{sub 2}O ratio in cometary atmospheres. The CX data sets are incorporated into the modeling packages SPEX and Kronos .

  12. The Solar Wind-Mars Interaction Boundaries in Three Dimensions

    Science.gov (United States)

    Gruesbeck, J.; Espley, J. R.; Connerney, J. E. P.; DiBraccio, G. A.; Soobiah, Y. I. J.

    2017-12-01

    The Martian magnetosphere is a product of the interaction of Mars with the interplanetary magnetic field and the supersonic solar wind. A bow shock forms upstream of the planet as the solar wind is diverted around the planet. Closer to the planet another boundary is located that separates the shock-heated solar wind plasma from the planetary plasma in the Martian magnetosphere. The Martian magnetosphere is induced by the pile-up of the interplanetary magnetic field. This induced magnetospheric boundary (IMB) has been referred to by different names, in part due to the observations available at the time. The location of these boundaries have been previously analyzed using data from Phobos 2, Mars Global Surveyor, and Mars Express resulting in models describing their average shapes. Observations of individual transitions demonstrate that it is a boundary with a finite thickness. The MAVEN spacecraft has been in orbit about Mars since November 2014 resulting in many encounters of the spacecraft with the boundaries. Using data from the Particle and Fields Package (PFP), we identify over 1000 bow shock crossings and over 4000 IMB crossings that we use to model the average locations. We model the boundaries as a 3-dimensional surface allowing observations of asymmetry. The average location of the bow shock and IMB lies further from the planet in the southern hemisphere, where stronger crustal fields are present. The MAVEN PFP dataset allows concurrent observations of the magnetic field and plasma environment to investigate the nature of the IMB and the relationship of the boundary to the different plasma signatures. Finally, we model the upstream and downstream encounters of the boundaries separately to produce shell models that quantify the finite thicknesses of the boundaries.

  13. Solar wind control of stratospheric temperatures in Jupiter's auroral regions?

    Science.gov (United States)

    Sinclair, James Andrew; Orton, Glenn; Kasaba, Yasumasa; Sato, Takao M.; Tao, Chihiro; Waite, J. Hunter; Cravens, Thomas; Houston, Stephen; Fletcher, Leigh; Irwin, Patrick; Greathouse, Thomas K.

    2017-10-01

    Auroral emissions are the process through which the interaction of a planet’s atmosphere and its external magnetosphere can be studied. Jupiter exhibits auroral emission at a multitude of wavelengths including the X-ray, ultraviolet and near-infrared. Enhanced emission of CH4 and other stratospheric hydrocarbons is also observed coincident with Jupiter’s shorter-wavelength auroral emission (e.g. Caldwell et al., 1980, Icarus 44, 667-675, Kostiuk et al., 1993, JGR 98, 18823). This indicates that auroral processes modify the thermal structure and composition of the auroral stratosphere. The exact mechanism responsible for this auroral-related heating of the stratosphere has however remained elusive (Sinclair et al., 2017a, Icarus 292, 182-207, Sinclair et al., 2017b, GRL, 44, 5345-5354). We will present an analysis of 7.8-μm images of Jupiter measured by COMICS (Cooled Mid-Infrared Camera and Spectrograph, Kataza et al., 2000, Proc. SPIE(4008), 1144-1152) on the Subaru telescope. These images were acquired on January 11th, 12th, 13th, 14th, February 4, 5th and May 17th, 18th, 19th and 20th in 2017, allowing the daily variability of Jupiter’s auroral-related stratospheric heating to be tracked. Preliminary results suggest lower stratospheric temperatures are directly forced by the solar wind dynamical pressure. The southern auroral hotspot exhibited a significant increase in brightness temperature over a 24-hour period. Over the same time period, a solar wind propagation model (Tao et al. 2005, JGR 110, A11208) predicts a strong increase in the solar wind dynamical pressure at Jupiter.

  14. A Deeper Understanding of Stability in the Solar Wind: Applying Nyquist's Instability Criterion to Wind Faraday Cup Data

    Science.gov (United States)

    Alterman, B. L.; Klein, K. G.; Verscharen, D.; Stevens, M. L.; Kasper, J. C.

    2017-12-01

    Long duration, in situ data sets enable large-scale statistical analysis of free-energy-driven instabilities in the solar wind. The plasma beta and temperature anisotropy plane provides a well-defined parameter space in which a single-fluid plasma's stability can be represented. Because this reduced parameter space can only represent instability thresholds due to the free energy of one ion species - typically the bulk protons - the true impact of instabilities on the solar wind is under estimated. Nyquist's instability criterion allows us to systematically account for other sources of free energy including beams, drifts, and additional temperature anisotropies. Utilizing over 20 years of Wind Faraday cup and magnetic field observations, we have resolved the bulk parameters for three ion populations: the bulk protons, beam protons, and alpha particles. Applying Nyquist's criterion, we calculate the number of linearly growing modes supported by each spectrum and provide a more nuanced consideration of solar wind stability. Using collisional age measurements, we predict the stability of the solar wind close to the sun. Accounting for the free-energy from the three most common ion populations in the solar wind, our approach provides a more complete characterization of solar wind stability.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. Current system of the solar wind: results of numerical calculation

    International Nuclear Information System (INIS)

    Pisanko, Yu.V.

    1985-01-01

    Results of numerical calculations of surface current in the interplanetary current layer and steady volume current in the solar wind for heliocentric distances (1-10)Rsub(s) (Rsub(s) is the Sun radius) are given. The strength of current dependence on spatial coordinates is considered. Stationary nondissipative magnetohydrodynamic corona expansion (SNMCE) in the reference system rotating with the Sun is studied. Calculations show that three-dimensional current system of nonaxial-symmetric and nonsymmetric relatively to helioequator plane of SNMCE is more complicated than the zonal ring current around the Sun, which is the only component of the current system in spatial symmetric case

  17. Effects in atmospheric electricity daily variation controlled by solar wind

    International Nuclear Information System (INIS)

    Ptitsyna, N.G.; Tyasto, M.I.; Levitin, A.E.; Gromova, L.A.; Tuomi, T.; AN SSSR, Moscow

    1995-01-01

    An analysis of fair weather atmospheric electricity, one of the environmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at Helsinki is found between disturbed and extremely quiet conditions in the magnetosphere in winter before midnight. The comparison with the numerical model of the ionospheric electric field based on the solar wind parameters reveals that the maximum contribution of the magnetospheric-ionospheric generator to atmospheric electric field is about 100-150 v/m which assumes values of about 30% of the surface field. 8 refs.; 2 figs

  18. Simulation of transcontinental wind and solar PV generation time series

    DEFF Research Database (Denmark)

    Nuño Martinez, Edgar; Maule, Petr; Hahmann, Andrea N.

    2018-01-01

    to the technical characteristics of individual installations spread across large regions. The proposed methodology is validated using actual power data in Europe and can be applied to represent intermittent generation in network development plans, reliability and market studies, as well as operational guidelines.......The deployment of Renewable Energy Sources (RES) is driving modern power systems towards a fundamental green transition. In this regard, there is a need to develop models to accurately capture the variability of wind and solar photovoltaic (PV) power, at different geographical and temporal scales...

  19. Solar wind monitor—a school geophysics project

    Science.gov (United States)

    Robinson, Ian

    2018-05-01

    Described is an established geophysics project to construct a solar wind monitor based on a nT resolution fluxgate magnetometer. Low-cost and appropriate from school to university level it incorporates elements of astrophysics, geophysics, electronics, programming, computer networking and signal processing. The system monitors the earth’s field in real-time uploading data and graphs to a website every few minutes. Modular design encourages construction and testing by teams of students as well as expansion and refinement. The system has been tested running unattended for months at a time. Both the hardware design and software is published as open-source [1, 10].

  20. Proton fire hose instabilities in the expanding solar wind

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr

    2017-01-01

    Roč. 83, č. 1 (2017), č. článku 705830105. ISSN 0022-3778 Institutional support: RVO:68378289 Keywords : astrophysicals plasmas * plasma expansion * plasma simulation Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.160, year: 2016 https://www.cambridge.org/ core /journals/journal-of-plasma-physics/article/proton-fire-hose-instabilities-in-the-expanding-solar-wind/6BA70378B25728533588A1A68073AC2F

  1. Assessing temporal complementarity of solar, wind and hydrokinetic energy

    Directory of Open Access Journals (Sweden)

    Jurasz Jakub

    2016-01-01

    Full Text Available Renewable energy sources (RES exhibit various characteristics when it comes to their availability in time and space domain. Some are characterised by significant variability and limited predictability. This makes their integration to the power grid a complicated task. Temporal and spatial complementarity of RES is perceived as one of the possible ways to facilitate the process of integration. This paper investigates the concept of temporal complementarity of solar wind and hydrokinetic energy in case of two sites in Poland. Obtained results indicate existence of some beneficial complementarity on inter-annual and annual time scale. Combination of those three RES in one hybrid system makes power source more reliable.

  2. Three Sides Billboard Wind-Solar Hybrid System Design

    Directory of Open Access Journals (Sweden)

    Bai Xuefeng

    2015-01-01

    Full Text Available With the high development of world economy, the demand of energy is increasing all the time, As energy shortage and environment problem are increasing outstanding, Renewable energy has been attracting more and more attention. A kind of three sides billboard supply by wind-Solar hybrid system has been designed in this paper, the overall structure of the system, components, working principle and control strategy has been analyzed from the system perspective. The software and hardware of the system are debugged together and the result is acquired. System function is better and has achieved the expected results.

  3. Polarization state of hydromagnetic fluctuations in the solar wind

    International Nuclear Information System (INIS)

    Bavassano, B.; Dobrowolny, M.; Mariani, F.; Ness, N.F.

    1981-01-01

    From presently available observations one can infer that the Alfvenic turbulence measured in the solar wind, predominantly on trailing edges of high-speed streams, is a mixture of modes with two different polarizations, namely. Alfvenic modes and modes which are the incompressible limit of slow magnetosonic waves. Using Helios 2 magnetic data and a variance analysis, we have separated parallel (to the mean field) and perpendicular components of the fluctuations and studied the possible correlation between such components which would be predicted as a consequence of the imcompressible character of the turbulence. Correlations between eigenvalues of the variance matrix are also investigated and discussed

  4. Solar Wind Interaction and Impact on the Venus Atmosphere

    Science.gov (United States)

    Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

    2017-11-01

    Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

  5. Energy coupling function and solar wind-magnetosphere dynamo

    International Nuclear Information System (INIS)

    Kan, J.R.; Lee, L.C.

    1979-01-01

    The power delivered by the solar wind dynamo to the open magnetosphere is calculated based on the concept of field line reconnection, independent of the MHD steady reconnection theories. By recognizing a previously overlooked geometrical relationship between the reconnection electric field and the magnetic field, the calculated power is shown to be approximately proportional to the Akasofu-Perreault energy coupling function for the magnetospheric substorm. In addition to the polar cap potential, field line reconnection also gives rise to parallel electric fields on open field lines in the high-latitude cusp and the polar cap reions

  6. Proton thermal energetics in the solar wind: Helios reloaded

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel M.; Štverák, Štěpán; Matteini, L.; Velli, M.

    2013-01-01

    Roč. 118, č. 4 (2013), s. 3151-3165 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041; GA ČR GAP209/12/2023 EU Projects: European Commission(XE) 263340 - SWIFF Grant - others:EU(XE) SHOCK Project No. 284515 Institutional support: RVO:67985815 ; RVO:68378289 Keywords : solar wind * proton energetics * turbulent heating Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics; BL - Plasma and Gas Discharge Physics (UFA-U) Impact factor: 3.440, year: 2013

  7. Cause of solar wind speed variations observed at 1 a.u

    International Nuclear Information System (INIS)

    Hakamada, K.; Akasofu, S.

    1981-01-01

    An attempt is made to interpret solar wind variations observed at the earth's distance, namely the solar cycle variations, the semi-annual variations, and the 27-day variations, as well as the polarity changes of the interplanetary magnetic field, mainly in terms of two effects, a positive latitudinal gradient of the solar wind speed and a wobbling solar dipole, combined with the annual (heliospheric) latitudinal excursion of the earth. It is shown that a significant part of the solar wind variations observed at the earth's distance and the changes of polarity pattern of the interplanetary magnetic field can be reasonably well reproduced by the two effects

  8. Spectral broadening of planetary radar signals by the solar wind

    International Nuclear Information System (INIS)

    Harmon, J.K.; Coles, W.A.

    1983-01-01

    The microturbulence spectrum of the solar wind is estimated using the spectral broadening of planetary radar signals. Observations were made with the two radars (12.6 cm and 70 cm) at Arecibo Observatory during the 1979 and 1981 superior conjunctions of Venus. These observations, which span the solar distance range of 5.4 to 25.5 R/sub sun/, are the first of their type to be reported. The data are consistent with earlier observations where comparisons can be made. The flattening of the high-frequency portion of the spectrum near the Sun reported by Woo and Armstrong is confirmed. In one case clear evidence for an inner scale in the vicinity of 2 km is found. Two transients, 1979 August 15 and 1981 April 24-25, with rather different characteristics were observed

  9. The influence of solar wind variability on magnetospheric ULF wave power

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2015-06-01

    Full Text Available Magnetospheric ultra-low frequency (ULF oscillations in the Pc 4–5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind–IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996–2004 of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature, plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind–magnetosphere coupling.

  10. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

    Science.gov (United States)

    Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

    2011-06-24

    The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

  11. Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation

    Science.gov (United States)

    Ajello, J. M.

    1990-01-01

    Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

  12. Spectral Analysis of Geomagnetic Activity Indices and Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Jung-Hee Kim

    2014-06-01

    Full Text Available Solar variability is widely known to affect the interplanetary space and in turn the Earth’s electromagnetical environment on the basis of common periodicities in the solar and geomagnetic activity indices. The goal of this study is twofold. Firstly, we attempt to associate modes by comparing a temporal behavior of the power of geomagnetic activity parameters since it is barely sufficient searching for common peaks with a similar periodicity in order to causally correlate geomagnetic activity parameters. As a result of the wavelet transform analysis we are able to obtain information on the temporal behavior of the power in the velocity of the solar wind, the number density of protons in the solar wind, the AE index, the Dst index, the interplanetary magnetic field, B and its three components of the GSM coordinate system, BX, BY, BZ. Secondly, we also attempt to search for any signatures of influence on the space environment near the Earth by inner planets orbiting around the Sun. Our main findings are as follows: (1 Parameters we have investigated show periodicities of ~ 27 days, ~ 13.5 days, ~ 9 days. (2 The peaks in the power spectrum of BZ appear to be split due to an unknown agent. (3 For some modes powers are not present all the time and intervals showing high powers do not always coincide. (4 Noticeable peaks do not emerge at those frequencies corresponding to the synodic and/or sidereal periods of Mercury and Venus, which leads us to conclude that the Earth’s space environment is not subject to the shadow of the inner planets as suggested earlier.

  13. Scale Dependence of Magnetic Helicity in the Solar Wind

    Science.gov (United States)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  14. Fusion at counterstreaming ion beams - ion optic fusion (IOF)

    International Nuclear Information System (INIS)

    Gryzinski, M.

    1981-01-01

    The results of investigation are briefly reviewed in the field of ion optic fusion performed at the Institute of Nuclear Research in Swierk. The ion optic fusion concept is based on the possibility of obtaining fusion energy at highly ordered motion of ions in counterstreaming ion beams. For this purpose TW ion beams must be produced and focused. To produce dense and charge-neutralized ion beams the selective conductivity and ballistic focusing ideas were formulated and used in a series of RPI devices with low-pressure cylindrical discharge between grid-type electrodes. 100 kA, 30 keV deuteron beams were successfully produced and focused into the volume of 1 cm 3 , yielding 10 9 neutrons per 200 ns shot on a heavy ice target. Cylindrically convergent ion beams with magnetic anti-defocusing were proposed in order to reach a positive energy gain at reasonable energy level. (J.U.)

  15. Solar Wind Proton Temperature Anisotropy: Linear Theory and WIND/SWE Observations

    Science.gov (United States)

    Hellinger, P.; Travnicek, P.; Kasper, J. C.; Lazarus, A. J.

    2006-01-01

    We present a comparison between WIND/SWE observations (Kasper et al., 2006) of beta parallel to p and T perpendicular to p/T parallel to p (where beta parallel to p is the proton parallel beta and T perpendicular to p and T parallel to p are the perpendicular and parallel proton are the perpendicular and parallel proton temperatures, respectively; here parallel and perpendicular indicate directions with respect to the ambient magnetic field) and predictions of the Vlasov linear theory. In the slow solar wind, the observed proton temperature anisotropy seems to be constrained by oblique instabilities, by the mirror one and the oblique fire hose, contrary to the results of the linear theory which predicts a dominance of the proton cyclotron instability and the parallel fire hose. The fast solar wind core protons exhibit an anticorrelation between beta parallel to c and T perpendicular to c/T parallel to c (where beta parallel to c is the core proton parallel beta and T perpendicular to c and T parallel to c are the perpendicular and parallel core proton temperatures, respectively) similar to that observed in the HELIOS data (Marsch et al., 2004).

  16. Extended MHD Turbulence and Its Applications to the Solar Wind

    Science.gov (United States)

    Abdelhamid, Hamdi M.; Lingam, Manasvi; Mahajan, Swadesh M.

    2016-10-01

    Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfvénic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal (k\\lt 1/{λ }I), Hall (1/{λ }I\\lt k\\lt 1/{λ }e), and electron inertia (k\\gt 1/{λ }e) regimes; k is the wavenumber and {λ }s=c/{ω }{ps} is the skin depth of species “s.” In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of -11/3 and -13/3 are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approximately -4 in this regime. It is thus plausible that these spectra may constitute a part of the (extended) inertial range, as opposed to the standard “dissipation” range paradigm.

  17. Reevaluation of the Solar Wind 36Ar/38Ar Ratio

    Science.gov (United States)

    Becker, R. H.; Schlutter, D. J.; Rider, P. E.; Pepin, R. O.

    1996-03-01

    The isotopic composition of solar wind (SW) argon is an important parameter in the modeling of the evolution of the terrestrial planet atmospheres. Anders and Grevesse assumed a 36Ar/38Ar ratio for SW of 5.31, essentially equal to that of air. Considerable evidence has since developed which indicates that this ratio is too low. Benkert et al. have reported their best estimate for the recent SW as 5.48 +/- 0.05, determined from measurements of lunar soil 71501. Based on Ar data obtained from surface oxidation of a metal separate from the Weston meteorite and from an uncontrolled etch of lunar sample 67701, reported by our group previously, we consider even this value to be too low. Since values of 5.75 to 5.85 were reported by Black for initial low temperature (fairly high SW 36Ar/38Ar ratio (in the range of ~5.6 to ~5.7), we decided to analyze Kapoeta for its light solar wind gases using the acid-etching techniques developed in our laboratory based on the CSSE procedure of Benkert et al.

  18. MHD turbulence in the solar wind: evolution and anisotropy

    International Nuclear Information System (INIS)

    Horbury, T. S.; Forman, M. A.; Oughton, S.

    2005-01-01

    Spacecraft measurements in the solar wind offer the opportunity to study magnetohydrodynamic turbulence in a collisionless plasma in great detail. We review some of the key results of the study of this medium: the presence of large amplitude Alfven waves propagating predominantly away from the Sun; the existence of an active turbulent cascade; and intermittency similar to that in neutral fluids. The presence of a magnetic field leads to anisotropy of the fluctuations, which are predominantly perpendicular to this direction, as well as anisotropy of the spectrum. Some models suggest that MHD turbulence can evolve to a state with power predominantly in wave vectors either parallel to the magnetic field (slab fluctuations) or approximately perpendicular to it (2D). We present results of a new, wavelet-based analysis of magnetic field fluctuations in the solar wind, and demonstrate that the 2D component has a spectral index near the Kolmogorov value of 5/3, while slab fluctuations have a spectral index near 2. We also estimate the relative power levels in slab and 2D fluctuations, as well as the level of compressive fluctuations. Deviations of the data from the simple slab/2D model suggest the presence of power in intermediate directions and we compare our data with critical balance models. (Author)

  19. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Volokitin, A. S. [IZMIRAN, Troitsk, 142190, Moscow (Russian Federation); Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr [Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, 3A Av. de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France)

    2015-08-20

    Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.

  20. Corotating pressure waves without streams in the solar wind

    International Nuclear Information System (INIS)

    Burlaga, L.F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun

  1. Observations & modeling of solar-wind/magnetospheric interactions

    Science.gov (United States)

    Hoilijoki, Sanni; Von Alfthan, Sebastian; Pfau-Kempf, Yann; Palmroth, Minna; Ganse, Urs

    2016-07-01

    The majority of the global magnetospheric dynamics is driven by magnetic reconnection, indicating the need to understand and predict reconnection processes and their global consequences. So far, global magnetospheric dynamics has been simulated using mainly magnetohydrodynamic (MHD) models, which are approximate but fast enough to be executed in real time or near-real time. Due to their fast computation times, MHD models are currently the only possible frameworks for space weather predictions. However, in MHD models reconnection is not treated kinetically. In this presentation we will compare the results from global kinetic (hybrid-Vlasov) and global MHD simulations. Both simulations are compared with in-situ measurements. We will show that the kinetic processes at the bow shock, in the magnetosheath and at the magnetopause affect global dynamics even during steady solar wind conditions. Foreshock processes cause an asymmetry in the magnetosheath plasma, indicating that the plasma entering the magnetosphere is not symmetrical on different sides of the magnetosphere. Behind the bow shock in the magnetosheath kinetic wave modes appear. Some of these waves propagate to the magnetopause and have an effect on the magnetopause reconnection. Therefore we find that kinetic phenomena have a significant role in the interaction between the solar wind and the magnetosphere. While kinetic models cannot be executed in real time currently, they could be used to extract heuristics to be added in the faster MHD models.

  2. Kappa-Electrons Downstream of the Solar Wind Termination Shock

    Science.gov (United States)

    Fahr, H. J.

    2017-12-01

    A theoretical description of the solar wind electron distribution function downstream of the termination shock under the influence of the shock-induced injection of overshooting KeV-energetic electrons will be presented. A kinetic phasespace transport equation in the bulk frame of the heliosheath plasma flow is developed for the solar wind electrons, taking into account shock-induced electron injection, convective changes, magnetic cooling processes and whistler wave-induced energy diffusion. Assuming that the local electron distribution under the prevailing Non-LTE conditions can be represented by a local kappa function with a local kappa parameter that varies with the streamline coordinates, we determine the parameters of the resulting, initial kappa distribution for the downstream electrons. From this initial function spectral electron fluxes can be derived and can be compared with those measured by the VOYAGER-1 spacecraft in the range between 40 to 70 KeV. It can then be shown that with kappa values around kappa = 6 one can in fact fit these data very satisfactorily. In addition it is shown that for isentropic electron flows kappa-distributed electrons have to undergo simultaneous changes of both parameters, i.e. kappa and theta, of the electron kappa function. It is also shown then that under the influence of energy sinks and sources the electron flux becomes non-isentropic with electron entropies changing along the streamline.

  3. 3D Electric Waveforms of Solar Wind Turbulence

    Science.gov (United States)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.

    2018-01-01

    Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individual waveforms using the three-dimensional antenna system of the SWaves experiments on the STEREO spacecraft. Samples are chosen using waveforms with an apparent periodic structure, selected visually. The short antennas of STEREO respond to density fluctuations and to electric fields. Measurement of four quantities using only three antennas presents a problem. Methods to overcome or to ignore this difficulty are presented. We attempt to decide whether the waveforms correspond to the whistler mode or the Alfvén mode by using the direction of rotation of the signal. Most of the waveforms are so oblique—nearly linearly polarized—that the direction cannot be determined. However, about one third of the waveforms can be identified, and whistlers and Alfvén waves are present in roughly equal numbers. The selected waveforms are very intense but intermittent and are orders of magnitude stronger than the average, yet their accumulated signal accounts for a large fraction of the average. The average, however, is supposed to be the result of a turbulent mixture of many waves, not short coherent events. This presents a puzzle for future work.

  4. On the nature of obstacles braking solar wind near Mars and Venera planets and on specific features of the interaction between solar wind and atmospheres of these planets

    International Nuclear Information System (INIS)

    Breus, T.K.; Gringauz, K.I.

    1980-01-01

    Discussed is the nature of obstacles braking solar wind near Mars and Venera according to the data of soviet measurements at ''Mars'' and ''Venera'' series automatic interplanetary stations. It is shown that alongside with essential similarity there exist differences among the zones of flow-around of Venera and Mars by solar wind. Such differences include, particularly, smaller dimensions of the obstacle of Venera as compared with Mars, and correspondingly less remote position of the shock wave front from the planet, different peculiarities of property changes of day-time ionosphere depending on the Sun zenith angle and other. The analysis of the experimental data permits to conclude that ionosphere and correspondingly the induced magnetic field of Venera play a determining role in the formation of the shock wave and the picture of planet flow-around by solar wind, while the determining role in the obstacle formation braking solar wind of Mars is played by the eigen planet field

  5. Magnetic reconnection physics in the solar wind with Voyager 2

    Science.gov (United States)

    Stevens, Michael L.

    2009-08-01

    Magnetic reconnection is the process by which the magnetic topology evolves in collisionless plasmas. This phenomenon is fundamental to a broad range of astrophysical processes such as stellar flares, magnetospheric substorms, and plasma accretion, yet it is poorly understood and difficult to observe in situ . In this thesis, the solar wind plasma permeating interplanetary space is treated as a laboratory for reconnection physics. I present an exhaustive statistical approach to the identification of reconnection outflow jets in turbulent plasma and magnetic field time series data. This approach has been automated and characterized so that the resulting reconnection survey can be put in context with other related studies. The algorithm is shown to perform similarly to ad hoc studies in the inner heliosphere. Based on this technique, I present a survey of 138 outflow jets for the Voyager 2 spacecraft mission, including the most distant in situ evidence of reconnection discovered to date. Reconnection in the solar wind is shown to be strongly correlated with stream interactions and with solar activity. The solar wind magnetic field is found to be reconnecting via large, quasi-steady slow- mode magnetohydrodynamic structures as far out as the orbit of Neptune. The role of slow-mode shocks is explored and, in one instance, a well-developed reconnection structure is shown to be in good agreement with the Petschek theory for fast reconnection. This is the first reported example of a reconnection exhaust that satisfies the full jump conditions for a stationary slow-mode shock pair. A complete investigation into corotating stream interactions over the Voyager 2 mission has revealed that detectable reconnection structure occurs in about 23% of forced, global-scale current sheets. Contrary to previous studies, I find that signatures of this kind are most likely to be observed for current sheets where the magnetic field shear and the plasma-b are high. Evidence has been found

  6. Autonomous wind/solar power systems with battery storage

    Energy Technology Data Exchange (ETDEWEB)

    Protogeropoulos, C I

    1993-12-31

    The performance of an autonomous hybrid renewable energy system consisting of combined photovoltaic/wind power generation with battery storage is under evaluation in this thesis. Detailed mathematical analysis of the renewable components and the battery was necessary in order to establish the theoretical background for accurate simulation results. Model validation was achieved through experimentation. The lack of a sizing method to combine both hybrid system total cost and long-term reliability level was the result of an extended literature survey. The new achievements which are described in this research work refer to: - simplified modelling for the performance of amorphous-silicon photovoltaic panels for all solar irradiance levels. -development of a new current-voltage expression with respect to wind speed for wind turbine performance simulation. -establishment of the battery storage state of voltage, SOV, simulation algorithm for long-term dynamic operational conditions. The proposed methodology takes into account 8 distinct cases covering steady state and transient effects and can be used for autonomous system reliability calculations. -techno-economic evaluation of the size of the hybrid system components by considering both reliability and economic criteria as design parameters. Two sizing scenarios for the renewable components are examined : the average year method and the ``worst renewable`` month method. (Author)

  7. The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS

    International Nuclear Information System (INIS)

    Shearer, Paul; Raines, Jim M.; Lepri, Susan T.; Thomas, Jonathan W.; Gilbert, Jason A.; Landi, Enrico; Zurbuchen, Thomas H.; Von Steiger, Rudolf

    2014-01-01

    Using in situ ion spectrometry data from ACE/SWICS, we determine the solar wind Ne/O elemental abundance ratio and examine its dependence on wind speed and evolution with the solar cycle. We find that Ne/O is inversely correlated with wind speed, is nearly constant in the fast wind, and correlates strongly with solar activity in the slow wind. In fast wind streams with speeds above 600 km s –1 , we find Ne/O = 0.10 ± 0.02, in good agreement with the extensive polar observations by Ulysses/SWICS. In slow wind streams with speeds below 400 km s –1 , Ne/O ranges from a low of 0.12 ± 0.02 at solar maximum to a high of 0.17 ± 0.03 at solar minimum. These measurements place new and significant empirical constraints on the fractionation mechanisms governing solar wind composition and have implications for the coronal and photospheric abundances of neon and oxygen. The results are made possible by a new data analysis method that robustly identifies rare elements in the measured ion spectra. The method is also applied to Ulysses/SWICS data, which confirms the ACE observations and extends our view of solar wind neon into the three-dimensional heliosphere.

  8. The solar wind neon abundance observed with ACE/SWICS and ULYSSES/SWICS

    Energy Technology Data Exchange (ETDEWEB)

    Shearer, Paul; Raines, Jim M.; Lepri, Susan T.; Thomas, Jonathan W.; Gilbert, Jason A.; Landi, Enrico; Zurbuchen, Thomas H. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Von Steiger, Rudolf [International Space Science Institute, Hallerstrasse 6, CH-3012 Bern (Switzerland)

    2014-07-01

    Using in situ ion spectrometry data from ACE/SWICS, we determine the solar wind Ne/O elemental abundance ratio and examine its dependence on wind speed and evolution with the solar cycle. We find that Ne/O is inversely correlated with wind speed, is nearly constant in the fast wind, and correlates strongly with solar activity in the slow wind. In fast wind streams with speeds above 600 km s{sup –1}, we find Ne/O = 0.10 ± 0.02, in good agreement with the extensive polar observations by Ulysses/SWICS. In slow wind streams with speeds below 400 km s{sup –1}, Ne/O ranges from a low of 0.12 ± 0.02 at solar maximum to a high of 0.17 ± 0.03 at solar minimum. These measurements place new and significant empirical constraints on the fractionation mechanisms governing solar wind composition and have implications for the coronal and photospheric abundances of neon and oxygen. The results are made possible by a new data analysis method that robustly identifies rare elements in the measured ion spectra. The method is also applied to Ulysses/SWICS data, which confirms the ACE observations and extends our view of solar wind neon into the three-dimensional heliosphere.

  9. Transition region, coronal heating and the fast solar wind

    Science.gov (United States)

    Li, Xing

    2003-07-01

    It is assumed that magnetic flux tubes are strongly concentrated at the boundaries of supergranule convection cells. A power law spectrum of high frequency Alfvén waves with a spectral index -1 originating from the sun is assumed to supply all the energy needed to energize the plasma flowing in such magnetic flux tubes. At the high frequency end, the waves are eroded by ions due to ion cyclotron resonance. The magnetic flux concentration is essential since it allows a sufficiently strong energy flux to be carried by high frequency ion cyclotron waves and these waves can be readily released at the coronal base by cyclotron resonance. The main results are: 1. The waves are capable of creating a steep transition region, a hot corona and a fast solar wind if both the wave frequency is high enough and the magnetic flux concentration is sufficiently strong in the boundaries of the supergranule convection zone. 2. By primarily heating alpha particles only, it is possible to produce a steep transition region, a hot corona and a fast solar wind. Coulomb coupling plays a key role in transferring the thermal energy of alpha particles to protons and electrons at the corona base. The electron thermal conduction then does the remaining job to create a sharp transition region. 3. Plasma species (even ions) may already partially lose thermal equilibrium in the transition region, and minor ions may already be faster than protons at the very base of the corona. 4. The model predicts high temperature alpha particles (Talpha ~ 2 x 107 K) and low proton temperatures (Tp solar radii, suggesting that hydrogen Lyman lines observed by UVCS above coronal holes may be primarily broadened by Alfvén waves in this range.

  10. Does the magnetic expansion factor (fs) play a role in solar wind acceleration?

    Science.gov (United States)

    Wallace, Samantha; Arge, Charles N.; Pihlstrom, Ylva

    2017-08-01

    For the past 25 years, magnetic expansion factor (fs) has been a key parameter used in the calculation of terminal solar wind speed (vsw) in both the Wang-Sheeley-Arge (WSA) model and its predecessor the Wang-Sheeley (WS) model. Since the discovery of an inverse relationship between fs and vsw, the physical role that magnetic expansion factor plays in the acceleration of the solar wind has been explored and debated. In this study, we investigate whether magnetic expansion factor plays a causal role in determining the terminal speed of the solar wind or merely serves as proxy. To do so, we explore how fs, as determined by WSA, relates to vsw for two different scenarios: 1) extended periods where the fast solar wind emerges from the centers of large coronal holes, and 2) periods where the solar wind emerges from pseudostreamers. For these same scenarios, we will also consider an alternative empirical relationship between solar wind speed and the minimum angular distance at the photosphere of a solar wind source to the nearest coronal hole boundary (i.e., DCHB, θb). We then compare these two different prediction techniques directly with heliospheric observations (i.e., ACE, STEREO-A & B, Ulysses) of solar wind speed to determine whether one clearly out performs the other.

  11. ULF Wave Activity in the Magnetosphere: Resolving Solar Wind Interdependencies to Identify Driving Mechanisms

    Science.gov (United States)

    Bentley, S. N.; Watt, C. E. J.; Owens, M. J.; Rae, I. J.

    2018-04-01

    Ultralow frequency (ULF) waves in the magnetosphere are involved in the energization and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine 15 years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to L ˜ 6.6RE). We determine the relative contribution to ULF wave power from instantaneous nonderived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed vsw, southward interplanetary magnetic field component Bzstill account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation, and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters.

  12. COMPLEX MAPPING OF ENERGY RESOURCES FOR ALLOCATION OF SOLAR AND WIND ENERGY OBJECTS

    Directory of Open Access Journals (Sweden)

    B. A. Novakovskiy

    2016-01-01

    Full Text Available The paper presents developed methodology of solar and wind energy resources complex mapping at the regional level, taking into account the environmental and socio-economic factors affecting the placement of renewable energy facilities. Methodology provides a reasonable search and allocation of areas, the most promising for the placement of wind and solar power plants.

  13. Developing a hybrid solar/wind powered irrigation system for crops in the Great Plains

    Science.gov (United States)

    Some small scale irrigation systems (powered by wind or solar do not require subsidies, but this paper discusses ways to achieve an economical renewable energy powered center pivot irrigation system for crops in the Great Plains. By adding a solar-photovoltaic (PV) array together with a wind...

  14. Solar PV resource for higher penetration through a combined spatial aggregation with wind

    CSIR Research Space (South Africa)

    Bischof-Niemz, ST

    2016-06-01

    Full Text Available between wind and solar PV and how these would be reflected in the power system. The benefits of spatial distribution of renewables are well understood, but the impact of the combined spatial aggregation of wind and solar PV is central to the design...

  15. Analysis of Ion Charge States in Solar Wind and CMEs Arati ...

    Indian Academy of Sciences (India)

    states of various elements observed in situ in the solar wind and CMEs. The competing processes of ionization and recombination lead to depar- tures from collision ionization equilibrium. The use of this as a diagnostic of acceleration and heating processes of the solar wind and CMEs is sensi- tive to the accuracy of the ...

  16. Synoptic maps of solar wind parameters from in situ spacecraft observations

    Science.gov (United States)

    Gazis, P. R.

    1995-01-01

    Solar wind observations from the Interplanetary Monitoring Platform-8 (IMP-8) and Pioneer Venus Orbiter (PVO) spacecraft from 1982 until 1988 are combined to construct synoptic maps of solar wind parameters near 1 AU. Each map consists of 6 months of hourly averaged solar wind data, binned by heliographic latitude and Carrington longitude and projected back to the Sun. These maps show the structure and time evolution of solar wind streams near 1 AU in the heliographic latitudes of +/- 7.25 deg and provide and explicit picture of several phenomena, such as gradients, changes in the inclination of the heliospheric current sheet, and the relative positions of various structures in the inner heliosphere, that is difficult to obtain from single-spacecraft observations. The stream structure varied significantly during the last solar cycle. Between 1982 and early 1985, solar wind parameters did not depend strongly on heliographic latitude. During the last solar minimum, the solar wind developed significant latitudinal structure, and high-speed streams were excluded from the vicinity of the solar equator. The interplanetary magnetic field was strongly correlated with the coronal field, and the current sheet tended to coincide with the coronal neutral line. The solar wind speed showed the expected correlations with temperature, interplanetary magnetic field, and distance from the current sheet. The solar wind speed was anticorrelated with density, but the regions of highest density occurred east of the heliospheric current sheet and the regions of lowest solar wind speed. This is consistent with compression at the leading edge of high-speed streams.

  17. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= $T_{p, perp}/T_{p, parallel}{-}1$ became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the

  18. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the low latitude boundary layer (LLBL and duskside magnetosphere occurred under such inflated conditions that the magnetospheric magnetic pressure was insufficient to maintain pressure balance. In these crossings, the inner edge of

  19. Steady states of a diode with counterstreaming electron and positron beams

    Energy Technology Data Exchange (ETDEWEB)

    Ender, A. Ya.; Kuznetsov, V. I., E-mail: victor.kuznetsov@mail.ioffe.ru; Gruzdev, A. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation)

    2016-10-15

    Steady states of a plasma layer with counterstreaming beams of oppositely charged particles moving without collisions in a self-consistent electric field are analyzed. The study is aimed at clarifying the mechanism of generation and reconstruction of pulsar radiation. Such a layer also models the processes occurring in Knudsen plasma diodes with counterstreaming electron and ion beams. The steady-state solutions are exhaustively classified. The existence of several solutions at the same external parameters is established.

  20. Aspects of the equilibrium and stability of counterstreaming-ion tokamaks

    International Nuclear Information System (INIS)

    Cordey, J.G.; Haas, F.A.

    1976-01-01

    An anisotropic high-β equilibrium is derived for the counterstreaming-beam tokamak (CBT). The critical β of the CBT is found to be of comparable magnitude to that occurring in a similar model of a scalar-pressure tokamak. It is shown that the toroidal current which is essential for equilibrium can be maintained by the counterstreaming ions. Finally, a brief discussion of the stability of the device is given. (author)

  1. Elsaesser variable analysis of fluctuations in the ion foreshock and undisturbed solar wind

    Science.gov (United States)

    Labelle, James; Treumann, Rudolf A.; Marsch, Eckart

    1994-01-01

    Magnetohydrodynamics (MHD) fluctuations in the solar wind have been investigated previously by use of Elsaesser variables. In this paper, we present a comparison of the spectra of Elsaesser variables in the undisturbed solar wind at 1 AU and in the ion foreshock in front of the Earth. Both observations take place under relatively strong solar wind flow speed conditions (approximately equal 600 km/s). In the undisturbed solar wind we find that outward propagating Alfven waves dominate, as reported by other observers. In the ion foreshock the situation is more complex, with neither outward nor inward propagation dominating over the entire range investigated (1-10 mHz). Measurements of the Poynting vectors associated with the fluctuations are consistent with the Elsaesser variable analysis. These results generally support interpretations of the Elsaesser variables which have been made based strictly on solar wind data and provide additional insight into the nature of the ion foreshock turbulence.

  2. Contribution of Strong Discontinuities to the Power Spectrum of the Solar Wind

    International Nuclear Information System (INIS)

    Borovsky, Joseph E.

    2010-01-01

    Eight and a half years of magnetic field measurements (2 22 samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the ''inertial subrange'' with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this ''inertial subrange.'' Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

  3. AUTOMATIC DETECTION ALGORITHM OF DYNAMIC PRESSURE PULSES IN THE SOLAR WIND

    International Nuclear Information System (INIS)

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Li, Huijun; Xu, Xiaojun

    2015-01-01

    Dynamic pressure pulses (DPPs) in the solar wind are a significant phenomenon closely related to the solar-terrestrial connection and physical processes of solar wind dynamics. In order to automatically identify DPPs from solar wind measurements, we develop a procedure with a three-step detection algorithm that is able to rapidly select DPPs from the plasma data stream and simultaneously define the transition region where large dynamic pressure variations occur and demarcate the upstream and downstream region by selecting the relatively quiet status before and after the abrupt change in dynamic pressure. To demonstrate the usefulness, efficiency, and accuracy of this procedure, we have applied it to the Wind observations from 1996 to 2008 by successfully obtaining the DPPs. The procedure can also be applied to other solar wind spacecraft observation data sets with different time resolutions

  4. The effect of asymmetric solar wind on the Lyman α sky background

    International Nuclear Information System (INIS)

    Joselyn, J.A.; Holzer, T.E.

    1975-01-01

    The Lyman α (Ly α) sky background arises from the scattering of solar Ly α from a spatial distribution of neutral hydrogen in interplanetary space. This distribution is partially determined by the solar wind proton flux, which provides the principal mechanism of loss by charge exchange of the neutral hydrogen. By generating isophotal maps of scattered Ly α for several choices of interstellar wind direction and solar wind proton flux distributions, the results show that latitudinal variations of the solar wind proton flux can have a significant effect on the observed location and shape of the Ly α intensity maximum. This fact should aid in the interpretation of Ly α maps and also indicates a possible method for inferring values for the average solar wind proton flux out of the ecliptic plane

  5. Solar power. [comparison of costs to wind, nuclear, coal, oil and gas

    Science.gov (United States)

    Walton, A. L.; Hall, Darwin C.

    1990-01-01

    This paper describes categories of solar technologies and identifies those that are economic. It compares the private costs of power from solar, wind, nuclear, coal, oil, and gas generators. In the southern United States, the private costs of building and generating electricity from new solar and wind power plants are less than the private cost of electricity from a new nuclear power plant. Solar power is more valuable than nuclear power since all solar power is available during peak and midpeak periods. Half of the power from nuclear generators is off-peak power and therefore is less valuable. Reliability is important in determining the value of wind and nuclear power. Damage from air pollution, when factored into the cost of power from fossil fuels, alters the cost comparison in favor of solar and wind power. Some policies are more effective at encouraging alternative energy technologies that pollute less and improve national security.

  6. Effect of solar wind plasma parameters on space weather

    International Nuclear Information System (INIS)

    Rathore, Balveer S.; Gupta, Dinesh C.; Kaushik, Subhash C.

    2015-01-01

    Today's challenge for space weather research is to quantitatively predict the dynamics of the magnetosphere from measured solar wind and interplanetary magnetic field (IMF) conditions. Correlative studies between geomagnetic storms (GMSs) and the various interplanetary (IP) field/plasma parameters have been performed to search for the causes of geomagnetic activity and develop models for predicting the occurrence of GMSs, which are important for space weather predictions. We find a possible relation between GMSs and solar wind and IMF parameters in three different situations and also derived the linear relation for all parameters in three situations. On the basis of the present statistical study, we develop an empirical model. With the help of this model, we can predict all categories of GMSs. This model is based on the following fact: the total IMF B total can be used to trigger an alarm for GMSs, when sudden changes in total magnetic field B total occur. This is the first alarm condition for a storm's arrival. It is observed in the present study that the southward B z component of the IMF is an important factor for describing GMSs. A result of the paper is that the magnitude of B z is maximum neither during the initial phase (at the instant of the IP shock) nor during the main phase (at the instant of Disturbance storm time (Dst) minimum). It is seen in this study that there is a time delay between the maximum value of southward B z and the Dst minimum, and this time delay can be used in the prediction of the intensity of a magnetic storm two-three hours before the main phase of a GMS. A linear relation has been derived between the maximum value of the southward component of B z and the Dst, which is Dst = (−0.06) + (7.65) B z +t. Some auxiliary conditions should be fulfilled with this, for example the speed of the solar wind should, on average, be 350 km s −1 to 750 km s −1 , plasma β should be low and, most importantly, plasma temperature

  7. Three-fluid, three-dimensional magnetohydrodynamic solar wind model with eddy viscosity and turbulent resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-06-10

    We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are

  8. Regional variations in the health, environmental, and climate benefits of wind and solar generation

    OpenAIRE

    Siler-Evans, Kyle; Azevedo, Inês Lima; Morgan, M. Granger; Apt, Jay

    2013-01-01

    When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times more health and environmental benefits. A wind turbine in West Virginia displaces twice as much carbon dioxide as the same turbine in California. De...

  9. Techno-Economic Assessment of Concentrating Solar Power and Wind Hybridization in Jordan

    Directory of Open Access Journals (Sweden)

    Osama Ayadi

    2018-03-01

    A strong complementarity between wind and direct normal solar radiation was observed in the selected location in Jordan, which emphasizes the attractiveness of the selected hybrid system. The optimal configuration of the CSP-wind hybrid system was obtained with a solar field of a 2.6 solar multiple and a 5 hours energy storage. The achieved capacity factor was 94%, and the LCOE is lower than those resulted for standalone CSP plants.

  10. Self consistent MHD modeling of the solar wind from polar coronal holes

    International Nuclear Information System (INIS)

    Stewart, G. A.; Bravo, S.

    1996-01-01

    We have developed a 2D self consistent MHD model for solar wind flow from antisymmetric magnetic geometries. We present results in the case of a photospheric magnetic field which has a dipolar configuration, in order to investigate some of the general characteristics of the wind at solar minimum. As in previous studies, we find that the magnetic configuration is that of a closed field region (a coronal helmet belt) around the solar equator, extending up to about 1.6 R · , and two large open field regions centred over the poles (polar coronal holes), whose magnetic and plasma fluxes expand to fill both hemispheres in interplanetary space. In addition, we find that the different geometries of the magnetic field lines across each hole (from the almost radial central polar lines to the highly curved border equatorial lines) cause the solar wind to have greatly different properties depending on which region it flows from. We find that, even though our simplified model cannot produce realistic wind values, we can obtain a polar wind that is faster, less dense and hotter than equatorial wind, and found that, close to the Sun, there exists a sharp transition between the two wind types. As these characteristics coincide with observations we conclude that both fast and slow solar wind can originate from coronal holes, fast wind from the centre, slow wind from the border

  11. Cost-covering remuneration - wind and solar energy skinned

    International Nuclear Information System (INIS)

    Niederhaeusern, A.

    2008-01-01

    In this article, the details of Switzerland's cost-covering remuneration scheme for electrical energy from renewable resources are discussed. Several experts from the renewable energies area express their opinions on the scheme's tariffs for the remuneration of electrical energy fed into the public mains. Wind energy is quoted as being 'skinned', with a lower tariff than before and solar energy is quoted as being promoted 'with the hand brake still on'. Geothermal energy and power from biomass power stations is quoted as being 'undamaged' by the new remuneration system. In general, the opinion is expressed that small investors and producers have, once more, been put at a disadvantage. The situation in Switzerland is briefly compared with that in Germany, France, Spain and Italy. An overview of the tariffs is presented in tabular form

  12. Critical materials: wind industry and solar industry are battling

    International Nuclear Information System (INIS)

    Anon.

    2015-01-01

    Neodymium, dysprosium, tellurium, indium and gallium are materials whose shortage and price fluctuations could have an impact on the development of wind energy and solar energy as about a quarter of the production of rare earth elements is used for the fabrication of permanent magnets. Between 1966 and 1984 the United States were the first producer in the world, then the production of these materials has moved little by little towards China. In 2010 China produced 97% of rare earth elements and in the same year it reduced the quantities to export which led to a panic in the market. Now governments and the industry are facing the challenge. New production capacities have been opened particularly in the United-States and Australia, ancient mines have been re-opened, recycling policies have been developed and an optimization of the use of rare-earth elements has been favored. (A.C.)

  13. Solar wind interaction with type-1 comet tails

    International Nuclear Information System (INIS)

    Ershkovich, A.I.

    1977-01-01

    A comet tail is considered as a plasma cylinder separated by a tangential discontinuity surface from the solar wind. Under typical conditions a comet tail boundary is shown to undergo the Kelvin-Helmholtz instability. With infinite amplitude the stabilizing effect of the magnetic field increases, and waves become stable. The proposed model supplies the detailed quantitative description of helical waves observed in type-1 comet tails. This theory enables the evaluation of the comet tail magnetic field by means of the observations of helical waves. The magnetic field in the comet tail turns out to be of the order of the interplanetary field. This conclusion seems to be in accordance with Alfven's idea that the magnetic field in type-1 comet tails is a captured interplanetary field. (Auth.)

  14. Particle acceleration and reconnection in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Le Roux, J. A.; Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama, Huntsville, AL 35805 (United States); Department of Space Science, University of Alabama, Huntsville, AL 35899 (United States); Khabarova, O. [Heliophysical Laboratory, IZMIRAN, Troitsk, Moscow 142190 (Russian Federation); Cummings, A. C.; Stone, E. C. [California Institute of Technology, Mail Code 290-17, Pasadena, CA 91125 (United States); Decker, R. B. [Johns Hopkins University/Applied Physics Lab., Laurel, MD 20723-6099 (United States)

    2016-03-25

    An emerging paradigm for the dissipation of magnetic turbulence in the supersonic solar wind is via localized quasi-2D small-scale magnetic island reconnection processes. An advection-diffusion transport equation for a nearly isotropic particle distribution describes particle transport and energization in a region of interacting magnetic islands [1; 2]. The dominant charged particle energization processes are 1) the electric field induced by quasi-2D magnetic island merging, and 2) magnetic island contraction. The acceleration of charged particles in a “sea of magnetic islands” in a super-Alfvénic flow, and the energization of particles by combined diffusive shock acceleration (DSA) and downstream magnetic island reconnection processes are discussed.

  15. From the Solar Wind to the Magnetospheric Substorm

    Institute of Scientific and Technical Information of China (English)

    E.A. Ponomarev; P.A. Sedykh; O.V. Mager

    2005-01-01

    This paper gives a brief outline of the progression from the first substorm model developed in Ref.[4] and [8] based on Kennel's ideas[3], to the present views about the mechanism by which solar wind kinetic energy is converted to electromagnetic energy at the Bow Shock and by which this energy is transferred to the magnetosphere in the form of current; about the transformation of the energy of this current to gas kinetic energy of convecting plasma tubes, and, finally, the back transformation of gas kinetic energy to electromagnetic energy in secondary magnetospheric MHD generators. The questions of the formation of the magnetospheric convection system, the nature of substorm break-up, and of the matching of currents in the magnetosphere-ionosphere system are discussed.

  16. Western Wind and Solar Integration Study Phase 2 (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Lew, D.; Brinkman, G.; Ibanez, E.; Kumar, N.; Lefton, S.; Jordan, G.; Venkataraman, S.; King, J.

    2013-06-01

    This presentation accompanies Phase 2 of the Western Wind and Solar Integration Study, a follow-on to Phase 1, which examined the operational impacts of high penetrations of variable renewable generation on the electric power system in the West and was one of the largest variable generation studies to date. High penetrations of variable generation can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 calculated these costs and emissions, and simulated grid operations for a year to investigate the detailed impact of variable generation on the fossil-fueled fleet. The presentation highlights the scope of the study and results.

  17. New Model of a Solar Wind Airplane for Geomatic Operations

    Science.gov (United States)

    Achachi, A.; Benatia, D.

    2015-08-01

    The ability for an aircraft to fly during a much extended period of time has become a key issue and a target of research, both in the domain of civilian aviation and unmanned aerial vehicles. This paper describes a new design and evaluating of solar wind aircraft with the objective to assess the impact of a new system design on overall flight crew performance. The required endurance is in the range of some hours in the case of law enforcement, border surveillance, forest fire fighting or power line inspection. However, other applications at high altitudes, such as geomatic operations for delivering geographic information, weather research and forecast, environmental monitoring, would require remaining airborne during days, weeks or even months. The design of GNSS non precision approach procedure for different airports is based on geomatic data.

  18. The structure of rotational discontinuities. [in solar wind

    Science.gov (United States)

    Neugebauer, M.

    1989-01-01

    This study examines the structures of a set of rotational discontinuities detected in the solar wind by the ISEE-3 spacecraft. It is found that the complexity of the structure increases as the angle theta between the propagation vector k and the magnetic field decreases. For rotational discontinuities that propagate at a large angle to the field with an ion (left-hand) sense of rotation, the magnetic hodograms tend to be flattened, in agreement with prior numerical simulations. When theta is large, angular 'overshoots' are often observed at one or both ends of the discontinuity. When the propagation is nearly parallel to the field (when theta is small), many different types of structure are seen, ranging from straight lines, to S-shaped curves, to complex, disorganized shapes.

  19. NEW MODEL OF A SOLAR WIND AIRPLANE FOR GEOMATIC OPERATIONS

    Directory of Open Access Journals (Sweden)

    A. Achachi

    2015-08-01

    Full Text Available The ability for an aircraft to fly during a much extended period of time has become a key issue and a target of research, both in the domain of civilian aviation and unmanned aerial vehicles. This paper describes a new design and evaluating of solar wind aircraft with the objective to assess the impact of a new system design on overall flight crew performance. The required endurance is in the range of some hours in the case of law enforcement, border surveillance, forest fire fighting or power line inspection. However, other applications at high altitudes, such as geomatic operations for delivering geographic information, weather research and forecast, environmental monitoring, would require remaining airborne during days, weeks or even months. The design of GNSS non precision approach procedure for different airports is based on geomatic data.

  20. Moving an asteroid with electric solar wind sail

    Science.gov (United States)

    Merikallio, S.; Janhunen, P.

    2010-12-01

    The electric solar wind sail (E-Sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-Sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-Sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-Sail for directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-Sail device to the asteroid. We assess alternative attachment strategies, namely straightforward direct towing with a cable and the gravity tractor method which works for a wider variety of situations. We also consider possible techniques to scale up the E-Sail force beyond the baseline one Newton level to deal with more imminent or larger asteroid or cometary threats. As a baseline case we consider an asteroid of effective diameter of 140 m and mass of 3 million tons, which can be deflected with a baseline 1 N E-Sail within 10 years. With a 5 N E-Sail the deflection could be achieved in 5 years. Once developed, the E-Sail would appear to provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in cases where the collision threat becomes known several years in advance.

  1. Particle acceleration via reconnection processes in the supersonic solar wind

    International Nuclear Information System (INIS)

    Zank, G. P.; Le Roux, J. A.; Webb, G. M.; Dosch, A.; Khabarova, O.

    2014-01-01

    An emerging paradigm for the dissipation of magnetic turbulence in the supersonic solar wind is via localized small-scale reconnection processes, essentially between quasi-2D interacting magnetic islands. Charged particles trapped in merging magnetic islands can be accelerated by the electric field generated by magnetic island merging and the contraction of magnetic islands. We derive a gyrophase-averaged transport equation for particles experiencing pitch-angle scattering and energization in a super-Alfvénic flowing plasma experiencing multiple small-scale reconnection events. A simpler advection-diffusion transport equation for a nearly isotropic particle distribution is derived. The dominant charged particle energization processes are (1) the electric field induced by quasi-2D magnetic island merging and (2) magnetic island contraction. The magnetic island topology ensures that charged particles are trapped in regions where they experience repeated interactions with the induced electric field or contracting magnetic islands. Steady-state solutions of the isotropic transport equation with only the induced electric field and a fixed source yield a power-law spectrum for the accelerated particles with index α = –(3 + M A )/2, where M A is the Alfvén Mach number. Considering only magnetic island contraction yields power-law-like solutions with index –3(1 + τ c /(8τ diff )), where τ c /τ diff is the ratio of timescales between magnetic island contraction and charged particle diffusion. The general solution is a power-law-like solution with an index that depends on the Alfvén Mach number and the timescale ratio τ diff /τ c . Observed power-law distributions of energetic particles observed in the quiet supersonic solar wind at 1 AU may be a consequence of particle acceleration associated with dissipative small-scale reconnection processes in a turbulent plasma, including the widely reported c –5 (c particle speed) spectra observed by Fisk and Gloeckler

  2. Non-Gaussian probability distributions of solar wind fluctuations

    Directory of Open Access Journals (Sweden)

    E. Marsch

    Full Text Available The probability distributions of field differences ∆x(τ=x(t+τ-x(t, where the variable x(t may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.

  3. Radiation Belt Transport Driven by Solar Wind Dynamic Pressure Fluctuations

    Science.gov (United States)

    Kress, B. T.; Hudson, M. K.; Ukhorskiy, A. Y.; Mueller, H.

    2012-12-01

    The creation of the Earth's outer zone radiation belts is attributed to earthward transport and adiabatic acceleration of electrons by drift-resonant interactions with electromagnetic fluctuations in the magnetosphere. Three types of radial transport driven by solar wind dynamic pressure fluctuations that have been identified are: (1) radial diffusion [Falthammer, 1965], (2) significant changes in the phase space density radial profile due to a single or few ULF drift-resonant interactions [Ukhorskiy et al., 2006; Degeling et al., 2008], and (3) shock associated injections of radiation belt electrons occurring in less than a drift period [Li et al., 1993]. A progress report will be given on work to fully characterize different forms of radial transport and their effect on the Earth's radiation belts. The work is being carried out by computing test-particle trajectories in electric and magnetic fields from a simple analytic ULF field model and from global MHD simulations of the magnetosphere. Degeling, A. W., L. G. Ozeke, R. Rankin, I. R. Mann, and K. Kabin (2008), Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves, textit{J. Geophys. Res., 113}, A02208, doi:10.1029/2007JA012411. Fälthammar, C.-G. (1965), Effects of Time-Dependent Electric Fields on Geomagnetically Trapped Radiation, J. Geophys. Res., 70(11), 2503-2516, doi:10.1029/JZ070i011p02503. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake (1993), Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, textit{Geophys. Res. Lett., 20}(22), 2423-2426, doi:10.1029/93GL02701. Ukhorskiy, A. Y., B. J. Anderson, K. Takahashi, and N. A. Tsyganenko (2006), Impact of ULF oscillations in solar wind dynamic pressure on the outer radiation belt electrons, textit{Geophys. Res. Lett., 33}(6), L06111, doi:10.1029/2005GL024380.

  4. Solar wind heating by an embedded quasi-isothermal pick-up ion fluid

    Directory of Open Access Journals (Sweden)

    H. J. Fahr

    Full Text Available It is well known that the solar wind plasma consists of primary ions of solar coronal origin and secondary ions of interstellar origin. Interstellar H-atoms penetrate into the inner heliosphere and when ionized there are converted into secondary ions. These are implanted into the magnetized solar wind flow and are essentially enforced to co-move with this flow. By nonlinear interactions with wind-entrained Alfvén waves the latter are processed in the co-moving velocity space. This pick-up process, however, also causes actions back upon the original solar wind flow, leading to a deceleration, as well as a heating of the solar wind plasma. The resulting deceleration is not only due to the loading effect, but also due to the action of the pressure gradient. To calculate the latter, it is important to take into account the stochastic acceleration that suffers at their convection out of the inner heliosphere by the quasi-linear interactions with MHD turbulences. Only then can the presently reported VOYAGER observations of solar wind decelerations and heatings in the outer heliosphere be understood in terms of the current, most likely values of interstellar gas parameters. In a consistent view of the thermodynamics of the solar wind plasma, which is composed of secondary ions and solar wind protons, we also derive that the latter are globally heated at their motion to larger solar distances. The arising heat transfer is due to the action of suprathermal ions which drive MHD waves that are partially absorbed by solar wind protons and thereby establish their observed quasi-polytropy. We obtain a quantitative expression for the solar wind proton pressure as a function of solar distance. This expression clearly shows the change from an adiabatic to a quasi-polytropic behaviour with a decreasing polytropic index at increasing distances, as has been observed by the VOYAGERS. This also allows one to calculate the average percentage of the intitial energy

  5. Solar wind heating by an embedded quasi-isothermal pick-up ion fluid

    Directory of Open Access Journals (Sweden)

    H. J. Fahr

    2002-10-01

    Full Text Available It is well known that the solar wind plasma consists of primary ions of solar coronal origin and secondary ions of interstellar origin. Interstellar H-atoms penetrate into the inner heliosphere and when ionized there are converted into secondary ions. These are implanted into the magnetized solar wind flow and are essentially enforced to co-move with this flow. By nonlinear interactions with wind-entrained Alfvén waves the latter are processed in the co-moving velocity space. This pick-up process, however, also causes actions back upon the original solar wind flow, leading to a deceleration, as well as a heating of the solar wind plasma. The resulting deceleration is not only due to the loading effect, but also due to the action of the pressure gradient. To calculate the latter, it is important to take into account the stochastic acceleration that suffers at their convection out of the inner heliosphere by the quasi-linear interactions with MHD turbulences. Only then can the presently reported VOYAGER observations of solar wind decelerations and heatings in the outer heliosphere be understood in terms of the current, most likely values of interstellar gas parameters. In a consistent view of the thermodynamics of the solar wind plasma, which is composed of secondary ions and solar wind protons, we also derive that the latter are globally heated at their motion to larger solar distances. The arising heat transfer is due to the action of suprathermal ions which drive MHD waves that are partially absorbed by solar wind protons and thereby establish their observed quasi-polytropy. We obtain a quantitative expression for the solar wind proton pressure as a function of solar distance. This expression clearly shows the change from an adiabatic to a quasi-polytropic behaviour with a decreasing polytropic index at increasing distances, as has been observed by the VOYAGERS. This also allows one to calculate the average percentage of the intitial energy

  6. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, L.; Landi, E., E-mail: lzh@umich.edu [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48105 (United States)

    2014-02-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  7. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    International Nuclear Information System (INIS)

    Zhao, L.; Landi, E.

    2014-01-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  8. RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

    Energy Technology Data Exchange (ETDEWEB)

    Airapetian, Vladimir S.; Usmanov, Arcadi V., E-mail: vladimir.airapetian@nasa.gov, E-mail: avusmanov@gmail.com [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2016-02-01

    Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

  9. RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

    International Nuclear Information System (INIS)

    Airapetian, Vladimir S.; Usmanov, Arcadi V.

    2016-01-01

    Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion

  10. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; hide

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  11. Decay of Solar Wind Turbulence behind Interplanetary Shocks

    Energy Technology Data Exchange (ETDEWEB)

    Pitňa, Alexander; Šafránková, Jana; Němeček, Zdeněk [Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, Prague, CZ-18000 (Czech Republic); Franci, Luca, E-mail: offelius@gmail.com [Dipartimento di Fisica e Astronomia, Universita degli Studi di Firenze, I-50125 Firenze (Italy)

    2017-07-20

    We investigate the decay of magnetic and kinetic energies behind IP shocks with motivation to find a relaxation time when downstream turbulence reaches a usual solar wind value. We start with a case study that introduces computation techniques and quantifies a contribution of kinetic fluctuations to the general energy balance. This part of the study is based on high-time (31 ms) resolution plasma data provided by the Spektr-R spacecraft. On the other hand, a statistical part is based on 92 s Wind plasma and magnetic data and its results confirm theoretically established decay laws for kinetic and magnetic energies. We observe the power-law behavior of the energy decay profiles and we estimated the power-law exponents of both kinetic and magnetic energy decay rates as −1.2. We found that the decay of MHD turbulence does not start immediately after the IP shock ramp and we suggest that the proper decay of turbulence begins when a contribution of the kinetic processes becomes negligible. We support this suggestion with a detailed analysis of the decay of turbulence at the kinetic scale.

  12. Majority of Solar Wind Intervals Support Ion-Driven Instabilities

    Science.gov (United States)

    Klein, K. G.; Alterman, B. L.; Stevens, M. L.; Vech, D.; Kasper, J. C.

    2018-05-01

    We perform a statistical assessment of solar wind stability at 1 AU against ion sources of free energy using Nyquist's instability criterion. In contrast to typically employed threshold models which consider a single free-energy source, this method includes the effects of proton and He2 + temperature anisotropy with respect to the background magnetic field as well as relative drifts between the proton core, proton beam, and He2 + components on stability. Of 309 randomly selected spectra from the Wind spacecraft, 53.7% are unstable when the ion components are modeled as drifting bi-Maxwellians; only 4.5% of the spectra are unstable to long-wavelength instabilities. A majority of the instabilities occur for spectra where a proton beam is resolved. Nearly all observed instabilities have growth rates γ slower than instrumental and ion-kinetic-scale timescales. Unstable spectra are associated with relatively large He2 + drift speeds and/or a departure of the core proton temperature from isotropy; other parametric dependencies of unstable spectra are also identified.

  13. Decay of Solar Wind Turbulence behind Interplanetary Shocks

    International Nuclear Information System (INIS)

    Pitňa, Alexander; Šafránková, Jana; Němeček, Zdeněk; Franci, Luca

    2017-01-01

    We investigate the decay of magnetic and kinetic energies behind IP shocks with motivation to find a relaxation time when downstream turbulence reaches a usual solar wind value. We start with a case study that introduces computation techniques and quantifies a contribution of kinetic fluctuations to the general energy balance. This part of the study is based on high-time (31 ms) resolution plasma data provided by the Spektr-R spacecraft. On the other hand, a statistical part is based on 92 s Wind plasma and magnetic data and its results confirm theoretically established decay laws for kinetic and magnetic energies. We observe the power-law behavior of the energy decay profiles and we estimated the power-law exponents of both kinetic and magnetic energy decay rates as −1.2. We found that the decay of MHD turbulence does not start immediately after the IP shock ramp and we suggest that the proper decay of turbulence begins when a contribution of the kinetic processes becomes negligible. We support this suggestion with a detailed analysis of the decay of turbulence at the kinetic scale.

  14. INFLUENCE OF THE AMBIENT SOLAR WIND FLOW ON THE PROPAGATION BEHAVIOR OF INTERPLANETARY CORONAL MASS EJECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Temmer, Manuela; Rollett, Tanja; Moestl, Christian; Veronig, Astrid M. [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, Bojan [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 Zagreb (Croatia); Odstrcil, Dusan [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO (United States)

    2011-12-20

    We study three coronal mass ejection (CME)/interplanetary coronal mass ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of Solar Terrestrial Relations Observatory Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in interplanetary (IP) space that is governed by two forces: the propelling Lorentz force and the drag force. We address the question: which heliospheric distance range does the drag become dominant and the CME adjust to the solar wind flow. To this end, we analyze speed differences between ICMEs and the ambient solar wind flow as a function of distance. The evolution of the ambient solar wind flow is derived from ENLIL three-dimensional MHD model runs using different solar wind models, namely, Wang-Sheeley-Arge and MHD-Around-A-Sphere. Comparing the measured CME kinematics with the solar wind models, we find that the CME speed becomes adjusted to the solar wind speed at very different heliospheric distances in the three events under study: from below 30 R{sub Sun }, to beyond 1 AU, depending on the CME and ambient solar wind characteristics. ENLIL can be used to derive important information about the overall structure of the background solar wind, providing more reliable results during times of low solar activity than during times of high solar activity. The results from this study enable us to obtain greater insight into the forces acting on CMEs over the IP space distance range, which is an important prerequisite for predicting their 1 AU transit times.

  15. INFLUENCE OF THE AMBIENT SOLAR WIND FLOW ON THE PROPAGATION BEHAVIOR OF INTERPLANETARY CORONAL MASS EJECTIONS

    International Nuclear Information System (INIS)

    Temmer, Manuela; Rollett, Tanja; Möstl, Christian; Veronig, Astrid M.; Vršnak, Bojan; Odstrčil, Dusan

    2011-01-01

    We study three coronal mass ejection (CME)/interplanetary coronal mass ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of Solar Terrestrial Relations Observatory Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in interplanetary (IP) space that is governed by two forces: the propelling Lorentz force and the drag force. We address the question: which heliospheric distance range does the drag become dominant and the CME adjust to the solar wind flow. To this end, we analyze speed differences between ICMEs and the ambient solar wind flow as a function of distance. The evolution of the ambient solar wind flow is derived from ENLIL three-dimensional MHD model runs using different solar wind models, namely, Wang-Sheeley-Arge and MHD-Around-A-Sphere. Comparing the measured CME kinematics with the solar wind models, we find that the CME speed becomes adjusted to the solar wind speed at very different heliospheric distances in the three events under study: from below 30 R ☉ , to beyond 1 AU, depending on the CME and ambient solar wind characteristics. ENLIL can be used to derive important information about the overall structure of the background solar wind, providing more reliable results during times of low solar activity than during times of high solar activity. The results from this study enable us to obtain greater insight into the forces acting on CMEs over the IP space distance range, which is an important prerequisite for predicting their 1 AU transit times.

  16. INERTIAL RANGE TURBULENCE OF FAST AND SLOW SOLAR WIND AT 0.72 AU AND SOLAR MINIMUM

    Energy Technology Data Exchange (ETDEWEB)

    Teodorescu, Eliza; Echim, Marius; Munteanu, Costel [Institute for Space Sciences, Măgurele (Romania); Zhang, Tielong [Space Research Institute, Graz (Austria); Bruno, Roberto [INAF-IAPS, Istituto di Astrofizica e Planetologia Spaziali, Rome (Italy); Kovacs, Peter, E-mail: eliteo@spacescience.ro [Geological and Geophysical Institute of Hungary, Budapest (Hungary)

    2015-05-10

    We investigate Venus Express observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of solar cycle 24. The power spectral densities (PSDs) of the magnetic field components have been computed for time intervals that satisfy the data integrity criteria and have been grouped according to the type of wind, fast and slow, defined for speeds larger and smaller, respectively, than 450 km s{sup −1}. The PSDs show higher levels of power for the fast wind than for the slow. The spectral slopes estimated for all PSDs in the frequency range 0.005–0.1 Hz exhibit a normal distribution. The average value of the trace of the spectral matrix is −1.60 for fast solar wind and −1.65 for slow wind. Compared to the corresponding average slopes at 1 AU, the PSDs are shallower at 0.72 AU for slow wind conditions suggesting a steepening of the solar wind spectra between Venus and Earth. No significant time variation trend is observed for the spectral behavior of both the slow and fast wind.

  17. Costs of solar and wind power variability for reducing CO2 emissions.

    Science.gov (United States)

    Lueken, Colleen; Cohen, Gilbert E; Apt, Jay

    2012-09-04

    We compare the power output from a year of electricity generation data from one solar thermal plant, two solar photovoltaic (PV) arrays, and twenty Electric Reliability Council of Texas (ERCOT) wind farms. The analysis shows that solar PV electricity generation is approximately one hundred times more variable at frequencies on the order of 10(-3) Hz than solar thermal electricity generation, and the variability of wind generation lies between that of solar PV and solar thermal. We calculate the cost of variability of the different solar power sources and wind by using the costs of ancillary services and the energy required to compensate for its variability and intermittency, and the cost of variability per unit of displaced CO(2) emissions. We show the costs of variability are highly dependent on both technology type and capacity factor. California emissions data were used to calculate the cost of variability per unit of displaced CO(2) emissions. Variability cost is greatest for solar PV generation at $8-11 per MWh. The cost of variability for solar thermal generation is $5 per MWh, while that of wind generation in ERCOT was found to be on average $4 per MWh. Variability adds ~$15/tonne CO(2) to the cost of abatement for solar thermal power, $25 for wind, and $33-$40 for PV.

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

    Directory of Open Access Journals (Sweden)

    Richardson Ian G.

    2012-05-01

    Full Text Available Using a classification of the near-Earth solar wind into three basic flow types: (1 High-speed streams associated with coronal holes at the Sun; (2 Slow, interstream solar wind; and (3 Transient flows originating with coronal mass ejections (CMEs at the Sun, including interplanetary CMEs and the associated upstream shocks and post-shock regions, we determine the drivers of geomagnetic storms of various size ranges based on the Kp index and the NOAA “G” criteria since 1964, close to the beginning of the space era, to 2011, encompassing more than four solar cycles (20–23. We also briefly discuss the occurrence of storms since the beginning of the Kp index in 1932, in the minimum before cycle 17. We note that the extended low level of storm activity during the minimum following cycle 23 is without precedent in this 80-year interval. Furthermore, the “typical” numbers of storm days/cycle quoted in the standard NOAA G storm table appear to be significantly higher than those obtained from our analysis, except for the strongest (G5 storms, suggesting that they should be revised downward.

  19. The large scale and long term evolution of the solar wind speed distribution and high speed streams

    International Nuclear Information System (INIS)

    Intriligator, D.S.

    1977-01-01

    The spatial and temporal evolution of the solar wind speed distribution and of high speed streams in the solar wind are examined. Comparisons of the solar wind streaming speeds measured at Earth, Pioneer 11, and Pioneer 10 indicate that between 1 AU and 6.4 AU the solar wind speed distributions are narrower (i.e. the 95% value minus the 5% value of the solar wind streaming speed is less) at extended heliocentric distances. These observations are consistent with one exchange of momentum in the solar wind between high speed streams and low speed streams as they propagate outward from the Sun. Analyses of solar wind observations at 1 AU from mid 1964 through 1973 confirm the earlier results reported by Intriligator (1974) that there are statistically significant variations in the solar wind in 1968 and 1969, years of solar maximum. High speed stream parameters show that the number of high speed streams in the solar wind in 1968 and 1969 is considerably more than the predicted yearly average, and in 1965 and 1972 less. Histograms of solar wind speed from 1964 through 1973 indicate that in 1968 there was the highest percentage of elevated solar wind speeds and in 1965 and 1972 the lowest. Studies by others also confirm these results although the respective authors did not indicate this fact. The duration of the streams and the histograms for 1973 imply a shifting in the primary stream source. (Auth.)

  20. Acceleration of the Fast Solar Wind through Minor Ions

    Science.gov (United States)

    Li, X.

    2004-01-01

    It is assumed that the magnetic flux tubes are strongly concentrated at the boundaries of the supergranule convection cells. A power law spectrum of high frequency Alfvén waves with a spectral index -1 originating from the sun is assumed to supply all the energy needed to energize the plasma flowing in such magnetic flux tubes. At the high frequency end, the waves are eroded by ions due to ion cyclotron resonance. The magnetic flux concentration is essential since it allows a sufficiently strong energy flux to be carried by high frequency ion cyclotron waves and these waves can be readily released at the coronal base by cyclotron resonance. The main results are: 1. By primarily heating alpha particles only, it is possible to produce a steep transition region, a hot corona and a fast solar wind. Coulomb coupling plays a key role in transferring the thermal energy of alpha particles to protons and electrons at the corona base. The electron thermal conduction then does the remaining job to create a sharp transition region. 2. Plasma species may already partially lose thermal equilibrium in the transition region, minor ions may already be faster than protons at the very bottom of the corona. 3. The model predicts high temperature alpha particles (T 2 × 107 K) and low proton temperatures (Tp solar radii, suggests that hydrogen Lyman lines observed by UVCS above coronal holes may be primarily broadened by Alfvén waves in this range.

  1. Regional variations in the health, environmental, and climate benefits of wind and solar generation.

    Science.gov (United States)

    Siler-Evans, Kyle; Azevedo, Inês Lima; Morgan, M Granger; Apt, Jay

    2013-07-16

    When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times more health and environmental benefits. A wind turbine in West Virginia displaces twice as much carbon dioxide as the same turbine in California. Depending on location, we estimate that the combined health, environmental, and climate benefits from wind or solar range from $10/MWh to $100/MWh, and the sites with the highest energy output do not yield the greatest social benefits in many cases. We estimate that the social benefits from existing wind farms are roughly 60% higher than the cost of the Production Tax Credit, an important federal subsidy for wind energy. However, that same investment could achieve greater health, environmental, and climate benefits if it were differentiated by region.

  2. Latitudinal distribution of the solar wind properties in the low- and high-pressure regimes: Wind observations

    Directory of Open Access Journals (Sweden)

    C. Lacombe

    Full Text Available The solar wind properties depend on λ, the heliomagnetic latitude with respect to the heliospheric current sheet (HCS, more than on the heliographic latitude. We analyse the wind properties observed by Wind at 1 AU during about 2.5 solar rotations in 1995, a period close to the last minimum of solar activity. To determine λ, we use a model of the HCS which we fit to the magnetic sector boundary crossings observed by Wind. We find that the solar wind properties mainly depend on the modulus |λ|. But they also depend on a local parameter, the total pressure (magnetic pressure plus electron and proton thermal pressure. Furthermore, whatever the total pressure, we observe that the plasma properties also depend on the time: the latitudinal gradients of the wind speed and of the proton temperature are not the same before and after the closest HCS crossing. This is a consequence of the dynamical stream interactions. In the low pressure wind, at low |λ|, we find a clear maximum of the density, a clear minimum of the wind speed and of the proton temperature, a weak minimum of the average magnetic field strength, a weak maximum of the average thermal pressure, and a weak maximum of the average β factor. This overdense sheet is embedded in a density halo. The latitudinal thickness is about 5° for the overdense sheet, and 20° for the density halo. The HCS is thus wrapped in an overdense sheet surrounded by a halo, even in the non-compressed solar wind. In the high-pressure wind, the plasma properties are less well ordered as functions of the latitude than in the low-pressure wind; the minimum of the average speed is seen before the HCS crossing. The latitudinal thickness of the high-pressure region is about 20°. Our observations are qualitatively consistent with the numerical model of Pizzo for the deformation of the heliospheric current sheet and plasma sheet.

    Key words: Interplanetary physics (solar wind

  3. Wind and Solar Energy Role in the Achievement of EU Climate Policy After 2020

    International Nuclear Information System (INIS)

    Knezevic, S.

    2016-01-01

    This paper grades the possible role of solar and wind energy in the generation of electricity after 2020. The development of those energy sources will be defined by the climate policy implemented based on the last year's Paris Climate Agreement, but also by the existing initiatives of the European Commission (2030 climate and energy framework and 2050 low-carbon economy). Additionally, electricity generation from RES is observed through the decrease of dependency on the import of fossil fuels outside of the EU. According to the report of the International Renewable Energy Agency (IRENA), the biggest share of RES power plants, after hydro power plants, in EU are wind and solar power plants. Both wind and sun are constantly available resources, but with variable specific power, which makes the maximal generation dependent on the time of day and/or weather (wind, clouds). Future increase of wind and solar energy has to be observed from various perspectives as to properly grade it for the next period, until 2020. Therefore, this paper considers the following, intertwined aspects: Maturity of wind and solar technologies and future trends, Price of electricity generation from wind and solar power plants, with an analysis of price decreasing trends; Possibilities of power energy system and measures for the acceptance of wind and solar power plants; Integrative approach to all forms and transformations of electricity; Market integration of RES - aspirations towards free trade(author).

  4. Solar-wind interactions with the Moon: nature and composition of nitrogen compounds

    International Nuclear Information System (INIS)

    Mukherjee, N.R.

    1981-01-01

    The lunar atmosphere and magnetic field are very tenuous. The solar wind, therefore, interacts directly with the lunar surface material and the dominant nature of interaction is essentially complete absorption of solar-wind particles by the surface material resulting in no upstream bowshock, but a cavity downstream. The solar-wind nitrogen ion species induce and undergo a complex set of reactions with the elements of lunar material and the solar-wind-derived trapped elements. The nitrogen concentration indigeneous to the lunar surface material is practically nil. Therefore any nitrogen and nitrogen compounds found in the lunar surface material are due to the solar-wind implantation of nitrogen ions. The flux of the solar-wind nitrogen ion species is about 6 X 10 3 cm -2 s -1 . Since there is no evidence for accumulation of nitrogen species in the lunar surface material, the outflux of nitrogen species from the lunar material to the atmosphere is the same as the solar-wind nitrogen ion flux. The species of the outflux are primarily NO and NH 3 , and their respective concentrations in the near surface lunar atmosphere are found to be 327 and 295 cm -3 . (Auth.)

  5. Observations of micro-turbulence in the solar wind near the sun with interplanetary scintillation

    Science.gov (United States)

    Yamauchi, Y.; Misawa, H.; Kojima, M.; Mori, H.; Tanaka, T.; Takaba, H.; Kondo, T.; Tokumaru, M.; Manoharan, P. K.

    1995-01-01

    Velocity and density turbulence of solar wind were inferred from interplanetary scintillation (IPS) observations at 2.3 GHz and 8.5 GHz using a single-antenna. The observations were made during September and October in 1992 - 1994. They covered the distance range between 5 and 76 solar radii (Rs). We applied the spectrum fitting method to obtain a velocity, an axial ratio, an inner scale and a power-law spectrum index. We examined the difference of the turbulence properties near the Sun between low-speed solar wind and high-speed solar wind. Both of solar winds showed acceleration at the distance range of 10 - 30 Rs. The radial dependence of anisotropy and spectrum index did not have significant difference between low-speed and high-speed solar winds. Near the sun, the radial dependence of the inner scale showed the separation from the linear relation as reported by previous works. We found that the inner scale of high-speed solar wind is larger than that of low-speed wind.

  6. Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

    Science.gov (United States)

    Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D.

    2013-08-01

    The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

  7. An illustrative note on the system price effect of wind and solar power. The German case

    International Nuclear Information System (INIS)

    Jaegemann, Cosima

    2014-01-01

    Exposing wind and solar power to the market price signal allows for cost-efficient investment decisions, as it incentivizes investors to account for the marginal value (MV el ) of renewable energy technologies. As shown by Lamont (2008), the MV el of wind and solar power units depends on their penetration level. More specifically, the MV el of wind and solar power units is a function of the respective unit's capacity factor and the covariance between its generation profile and the system marginal costs. The latter component of the MV el (i.e., the covariance) is found to decline as the wind and solar power penetration increases, displacing dispatchable power plants with higher short-run marginal costs of power production and thus reducing the system marginal costs in all generation hours. This so called 'system price effect' is analyzed in more detail in this paper. The analysis complements the work Lamont (2008) in two regards. First of all, an alternative expression for the MV el of wind and solar power units is derived, which shows that the MV el of fluctuating renewable energy technologies depends not only on their own penetration level but also on a variety of other parameters that are specific to the electricity system. Second, based on historical wholesale prices and wind and solar power generation data for Germany, a numerical 'ceteris paribus' example for Germany is presented which illustrates that the system price effect is already highly relevant for both wind and solar power generation in Germany.

  8. Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

    Science.gov (United States)

    Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

    1990-01-01

    Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

  9. Thermodynamic characteristics of a novel wind-solar-liquid air energy storage system

    Science.gov (United States)

    Ji, W.; Zhou, Y.; Sun, Y.; Zhang, W.; Pan, C. Z.; Wang, J. J.

    2017-12-01

    Due to the nature of fluctuation and intermittency, the utilization of wind and solar power will bring a huge impact to the power grid management. Therefore a novel hybrid wind-solar-liquid air energy storage (WS-LAES) system was proposed. In this system, wind and solar power are stored in the form of liquid air by cryogenic liquefaction technology and thermal energy by solar thermal collector, respectively. Owing to the high density of liquid air, the system has a large storage capacity and no geographic constraints. The WS-LAES system can store unstable wind and solar power for a stable output of electric energy and hot water. Moreover, a thermodynamic analysis was carried out to investigate the best system performance. The result shows that the increases of compressor adiabatic efficiency, turbine inlet pressure and inlet temperature all have a beneficial effect.

  10. Assessment of solar and wind energy potentials for three free economic and industrial zones of Iran

    International Nuclear Information System (INIS)

    Mohammadi, Kasra; Mostafaeipour, Ali; Sabzpooshani, Majid

    2014-01-01

    This paper aims to evaluate the potential of renewable energy sources of solar and wind in three free economic and industrial zones of Chabahar, Kish and Salafchegan in Iran. Feasibility of harnessing solar energy was investigated by using key solar parameters like monthly mean global, beam and diffuse solar radiation as well as clearness index. It was found that all locations had great potentials for utilizing different solar energy systems. Additionally, the monthly, seasonal, semi-yearly and yearly optimum tilt angles of south-facing solar surfaces were determined. For all zones, adjusting the tilt angle twice a year or in other words, the semi-yearly tilt adjustment for two periods of warm (April–September) and cold (October–March) were highly recommended, since it offers almost the same level of annual solar energy gain (SEG) as those of monthly and seasonal adjustments. Weibull Distribution Function (WDF) was performed for analyzing the wind potentials at different heights. It was found that Chabahar was not suitable for wind energy development, but Kish and Salafchegan with yearly wind powers of 111.28 W/m 2 and 114.34 W/m 2 , respectively ranked in class 2 which are considered marginal for wind power development. Three different wind turbine models were proposed for Kish and Salafchegan. - Highlights: • Feasibility of solar and wind energy for three locations of Iran was investigated. • All locations were suitable for solar energy utilization. • The optimum tilt angles of solar surfaces were determined. • Chabahar was unsuitable, but Kish and Salafchegan were marginal for wind purpose

  11. Voyager observations of solar wind proton temperature - 1-10 AU

    Science.gov (United States)

    Gazis, P. R.; Lazarus, A. J.

    1982-01-01

    Simultaneous measurements are made of the solar wind proton temperatures by the Voyager 1 and 2 spacecraft, far from earth, and the IMP 8 spacecraft in earth orbit. This technique permits a separation of radial and temporal variations of solar wind parameters. The average value of the proton temperature between 1 and 9 AU is observed to decrease as r (the heliocentric radius) to the -(0.7 + or - 0.2). This is slower than would be expected for adiabatic expansion. A detailed examination of the solar wind stream structure shows that considerable heating occurs at the interface between high and low speed streams.

  12. Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes

    Science.gov (United States)

    Gazis, P. R.; Mihalov, J. D.; Barnes, A.; Lazarus, A. J.; Smith, E. J.

    1989-01-01

    Data obtained from the electrostatic analyzers aboard the Pioneer 10 and 11 spacecraft and from the Faraday cup aboard Voyager 2 were used to study spatial gradients in the distant solar wind. Prior to mid-1985, both spacecraft observed nearly identical solar wind structures. After day 150 of 1985, the velocity structure at Voyager 2 became flatter, and the Voyager 2 velocities were smaller than those observed by Pioneer 11. It is suggested that these changes in the solar wind at low latitudes may be related to a change which occurred in the coronal hole structure in early 1985.

  13. Assessing the lifecycle greenhouse gas emissions from solar PV and wind energy

    DEFF Research Database (Denmark)

    Nugent, Daniel; Sovacool, Benjamin

    2014-01-01

    This paper critically screens 153 lifecycle studies covering a broad range of wind and solar photovoltaic (PV) electricity generation technologies to identify 41 of the most relevant, recent, rigorous, original, and complete assessments so that the dynamics of their greenhouse gas (GHG) emissions...... profiles can be determined. When viewed in a holistic manner, including initial materials extraction, manufacturing, use and disposal/decommissioning, these 41 studies show that both wind and solar systems are directly tied to and responsible for GHG emissions. They are thus not actually emissions free......, this article uncovers best practices in wind and solar design and deployment that can better inform climate change mitigation efforts in the electricity sector...

  14. On a relation of geomagnetic activity, solar wind velocity and irregularity of daily rotation of the Earth

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Kiselev, V.M.

    1980-01-01

    A possibility of the presence of statistic relation between the changes of the Earth rotation regime and the mean velocity of solar wind is discussed. The ratio between the solar wind velocity observed and planetary index of geomagnetic activity am is used to determine the annual average values of solar wind velocity beyond the twentieth cycle of solar activity. The restored changes of solar wind velocity are compared with solar conditioned variations of the Earth day duration and it is shown that the correspondence takes place only at frequencies lower the frequency of 11-year cycle [ru

  15. FADING CORONAL STRUCTURE AND THE ONSET OF TURBULENCE IN THE YOUNG SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    DeForest, C. E. [Southwest Research Institute, 1050 Walnut Street, Boulder, CO (United States); Matthaeus, W. H. [Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Viall, N. M. [NASA/Goddard Space Flight Center, Mail Code 671, Greenbelt, MD 20771 (United States); Cranmer, S. R. [University of Colorado, Duane E226, Boulder, CO 80305 (United States)

    2016-09-10

    Above the top of the solar corona, the young, slow solar wind transitions from low- β , magnetically structured flow dominated by radial structures to high- β , less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10° from the Sun in processed, background-subtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory ( STEREO /HI1) in 2008 December, covering apparent distances from approximately 4° to 24° from the center of the Sun and spanning this transition in the large-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the corona and to anomalous relative brightening of locally dense puffs of solar wind that we term “flocculae.” We show that these phenomena are inconsistent with smooth radial flow, but consistent with the onset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind.

  16. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  17. Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind

    Science.gov (United States)

    DeForest, C. E.; Matthaeus, W. H.; Viall, N. M.; Cranmer, S. R.

    2016-01-01

    Above the top of the solar corona, the young, slow solar wind transitions from low-beta, magnetically structured flow dominated by radial structures to high-beta, less structured flow dominated by hydrodynamics. This transition, long inferred via theory, is readily apparent in the sky region close to 10deg from the Sun in processed, background-subtracted solar wind images. We present image sequences collected by the inner Heliospheric Imager instrument on board the Solar-Terrestrial Relations Observatory (STEREO/HI1) in 2008 December, covering apparent distances from approximately 4deg to 24deg from the center of the Sun and spanning this transition in the large-scale morphology of the wind. We describe the observation and novel techniques to extract evolving image structure from the images, and we use those data and techniques to present and quantify the clear textural shift in the apparent structure of the corona and solar wind in this altitude range. We demonstrate that the change in apparent texture is due both to anomalous fading of the radial striae that characterize the corona and to anomalous relative brightening of locally dense puffs of solar wind that we term "flocculae." We show that these phenomena are inconsistent with smooth radial flow, but consistent with the onset of hydrodynamic or magnetohydrodynamic instabilities leading to a turbulent cascade in the young solar wind.

  18. Solar wind and coronal structure near sunspot minimum: Pioneer and SMM observations from 1985-1987

    International Nuclear Information System (INIS)

    Mihalov, J.D.; Barnes, A.; Hundhausen, A.J.; Smith, E.J.

    1990-01-01

    The solar wind speeds observed in the outer heliosphere (20 to 40 AU heliocentric distance, approximately) by Pioneers 10 an 11, and at a heliocentric distance of 0.7 AU by the Pioneer Venus spacecraft, reveal a complex set of changes in the years near the recent sunspot minimum, 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations made from the Solar Maximum Mission spacecraft during the same epoch show a systematic variation in coronal structure and (by implication) the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet (or with heliomagnetic latitude), and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum. The authors confirm here that this basic organization of the solar wind speed persists in the outer heliosphere with an orientation of the neutral sheet consistent with that inferred at a heliocentric distance of a few solar radii, from the coronal observations

  19. Solar wind stream evolution at large heliocentric distances - Experimental demonstration and the test of a model

    Science.gov (United States)

    Gosling, J. T.; Hundhausen, A. J.; Bame, S. J.

    1976-01-01

    A stream propagation model which neglects all dissipation effects except those occurring at shock interfaces, was used to compare Pioneer-10 solar wind speed observations, during the time when Pioneer 10, the earth, and the sun were coaligned, with near-earth Imp-7 observations of the solar wind structure, and with the theoretical predictions of the solar wind structure at Pioneer 10 derived from the Imp-7 measurements, using the model. The comparison provides a graphic illustration of the phenomenon of stream steepening in the solar wind with the attendant formation of forward-reverse shock pairs and the gradual decay of stream amplitudes with increasing heliocentric distance. The comparison also provides a qualitative test of the stream propagation model.

  20. Smoothing out the volatility of South Africa’s wind and solar energy resources

    CSIR Research Space (South Africa)

    Mushwana, Crescent

    2015-10-01

    Full Text Available In the past, renewables were mainly driven by the US, Europe and China, but South Africa is slowly picking up. This presentation discusses South Africa's wind and solar resources as alternative energy resources....

  1. Momentum flux of the solar wind near planetary magnetospheres: a comparative study

    International Nuclear Information System (INIS)

    Perez de Tejada, H.

    1985-01-01

    A study of the velocity profiles of the shocked solar wind exterior to the magnetospheres of the Earth, Mars and Venus is presented. A characteristic difference exists between the conditions present in planets with and without a strong intrinsic magnetic field. In a strongly magnetized planet (as it is the case in the earth), the velocity of the solar wind near the magnetopause remains nearly constant along directions normal to that boundary. In weakly magnetized planets (Venus, Mars), on the other hand, the velocity profile near the magnetopause/ionopause exhibits a transverse gradient which implies decreased values of the momentum flux of the solar wind in those regions. The implications of the different behavior of the shocked solar wind are discussed in connection with the nature of the interaction process that takes place in each case. (author)

  2. Estimated solar wind-implanted helium-3 distribution on the Moon

    Science.gov (United States)

    Johnson, J. R.; Swindle, T.D.; Lucey, P.G.

    1999-01-01

    Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions.

  3. Optimization of hybrid system (wind-solar energy) for pumping water

    African Journals Online (AJOL)

    DR OKE

    Keywords: Renewable energy; pumping water; technical optimization; ... The country already start on a mega-project of solar power production (2000 MW) ...... with a wind turbine in a standalone renewable energy system based on hydrogen.

  4. Evolution of the solar wind acceleration region during 1990-1994

    International Nuclear Information System (INIS)

    Tokumaru, Munetoshi; Kondo, Tetsuro; Takaba, Hiroshi; Mori, Hirotaka; Tanaka, Takashi

    1996-01-01

    The single-station measurements of interplanetary scintillation (IPS) at 2GHz and 8GHz using the Kashima radio telescope are used to study the distribution of the solar wind velocity and density fluctuations near the sun. Wind velocities derived from our IPS data with the IPS co-spectrum method show a radial increase in the distance range between 10 and 30 Rs (solar radii). From the scintillation index analysis, it is found that the radial fall of density fluctuations in the solar wind is described by the power-law function. A series of Kashima IPS observations reveals that a pronounced change in velocity and turbulence level occurs at the polar region of the sun during 1990-1994. That is, the high-speed wind and the reduced-turbulence region develop there as the solar activity declines. This fact is consistent with the long-term evolution of the coronal magnetic structure inferred from He1083nm observations

  5. Effects of the Solar Wind Pressure on Mercury's Exosphere: Hybrid Simulations

    Science.gov (United States)

    Travnicek, P. M.; Schriver, D.; Orlando, T. M.; Hellinger, P.

    2017-12-01

    We study effects of the changed solar wind pressure on the precipitation of hydrogen on the Mercury's surface and on the formation of Mercury's magnetosphere. We carry out a set of global hybrid simulations of the Mercury's magnetosphere with the interplanetary magnetic field oriented in the equatorial plane. We change the solar wind pressure by changing the velocity of injected solar wind plasma (vsw = 2 vA,sw; vsw = 4 vA,sw; vsw = 6 vA,sw). For each of the cases we examine proton and electron precipitation on Mercury's surface and calculate yields of heavy ions released from Mercury's surface via various processes (namely: Photo-Stimulated Desorption, Solar Wind Sputtering, and Electron Stimulated Desorption). We study circulation of the released ions within the Mercury's magnetosphere for the three cases.

  6. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    Science.gov (United States)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  7. Comparative Validation of Realtime Solar Wind Forecasting Using the UCSD Heliospheric Tomography Model

    Science.gov (United States)

    MacNeice, Peter; Taktakishvili, Alexandra; Jackson, Bernard; Clover, John; Bisi, Mario; Odstrcil, Dusan

    2011-01-01

    The University of California, San Diego 3D Heliospheric Tomography Model reconstructs the evolution of heliospheric structures, and can make forecasts of solar wind density and velocity up to 72 hours in the future. The latest model version, installed and running in realtime at the Community Coordinated Modeling Center(CCMC), analyzes scintillations of meter wavelength radio point sources recorded by the Solar-Terrestrial Environment Laboratory(STELab) together with realtime measurements of solar wind speed and density recorded by the Advanced Composition Explorer(ACE) Solar Wind Electron Proton Alpha Monitor(SWEPAM).The solution is reconstructed using tomographic techniques and a simple kinematic wind model. Since installation, the CCMC has been recording the model forecasts and comparing them with ACE measurements, and with forecasts made using other heliospheric models hosted by the CCMC. We report the preliminary results of this validation work and comparison with alternative models.

  8. Seasonal optimal mix of wind and solar power in a future, highly renewable Europe

    Energy Technology Data Exchange (ETDEWEB)

    Heide, Dominik [Frankfurt Institute for Advanced Studies (FIAS) and Frankfurt International Graduate School for Science, Johann Wolfgang Goethe Universitaet, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); von Bremen, Lueder [ForWind - Center for Wind Energy Research, University of Oldenburg, Marie-Curie-Str. 1, D-26129 Oldenburg (Germany); Greiner, Martin [Corporate Research and Technology, Siemens AG, D-81730 Muenchen (Germany); Aarhus School of Engineering and Institute of Mathematical Sciences, Aarhus University, Ny Munkegade 118, 8000 Aarhus C (Denmark); Hoffmann, Clemens [Corporate Research and Technology, Siemens AG, D-81730 Muenchen (Germany); Speckmann, Markus; Bofinger, Stefan [Fraunhofer Institut fuer Windenergie und Energiesystemtechnik (IWES), Koenigstor 59, D-34119 Kassel (Germany)

    2010-11-15

    The renewable power generation aggregated across Europe exhibits strong seasonal behaviors. Wind power generation is much stronger in winter than in summer. The opposite is true for solar power generation. In a future Europe with a very high share of renewable power generation those two opposite behaviors are able to counterbalance each other to a certain extent to follow the seasonal load curve. The best point of counterbalancing represents the seasonal optimal mix between wind and solar power generation. It leads to a pronounced minimum in required stored energy. For a 100% renewable Europe the seasonal optimal mix becomes 55% wind and 45% solar power generation. For less than 100% renewable scenarios the fraction of wind power generation increases and that of solar power generation decreases. (author)

  9. Beam tracking strategies for studies of kinetic scales in the solar wind with THOR-CSW

    Science.gov (United States)

    De Keyser, Johan; Lavraud, Benoit; Neefs, Eddy; Berkenbosch, Sophie; Anciaux, Michel; Maggiolo, Romain

    2016-04-01

    Modern plasma spectrometers for monitoring the solar wind attempt to intelligently track the energy and direction of the solar wind beam in order to obtain solar wind velocity distributions more efficiently. Such beam tracking strategies offer some benefits, but also have their limitations and drawbacks. Benefits include an improved resolution and/or a faster velocity distribution function acquisition time. Limitations are due to instrument characteristics that tend to be optimized for a particular range of particle energies and arrival directions. A drawback is the risk to miss an important part of the velocity distribution or to lose track of the beam altogether. A comparison is presented of different beam tracking strategies under consideration for the THOR-CSW instrument in order to highlight a number of design decisions and their impact on the acquired velocity distributions. The gain offered by beam tracking in terms of increased time resolution turns out to be essential for studies of solar wind physics at kinetic scales.

  10. Sputtering of Lunar Regolith Simulant by Protons and Multicharged Heavy Ions at Solar Wind Energies

    International Nuclear Information System (INIS)

    Meyer, Fred W.; Harris, Peter R.; Taylor, C.N.; Meyer, Harry M. III; Barghouty, N.; Adams, J. Jr.

    2011-01-01

    We report preliminary results on sputtering of a lunar regolith simulant at room temperature by singly and multiply charged solar wind ions using quadrupole and time-of-flight (TOF) mass spectrometry approaches. Sputtering of the lunar regolith by solar-wind heavy ions may be an important particle source that contributes to the composition of the lunar exosphere, and is a possible mechanism for lunar surface ageing and compositional modification. The measurements were performed in order to assess the relative sputtering efficiency of protons, which are the dominant constituent of the solar wind, and less abundant heavier multicharged solar wind constituents, which have higher physical sputtering yields than same-velocity protons, and whose sputtering yields may be further enhanced due to potential sputtering. Two different target preparation approaches using JSC-1A AGGL lunar regolith simulant are described and compared using SEM and XPS surface analysis.

  11. Western Wind and Solar Integration Study Phase 3 – Frequency Response and Transient Stability

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N. W. [GE Energy Management, Schenectady, NY (United States); Shao, M. [GE Energy Management, Schenectady, NY (United States); Pajic, S. [GE Energy Management, Schenectady, NY (United States); D' Aquila, R. [GE Energy Management, Schenectady, NY (United States)

    2014-12-01

    Power system operators and utilities worldwide have concerns about the impact of high-penetration wind and solar generation on electric grid reliability (EirGrid 2011b, Hydro-Quebec 2006, ERCOT 2010). The stability of North American grids under these conditions is a particular concern and possible impediment to reaching future renewable energy goals. Phase 3 of the Western Wind and Solar Integration Study (WWSIS-3) considers a 33% wind and solar annual energy penetration level that results in substantial changes to the characteristics of the bulk power system, including different power flow patterns, different commitment and dispatch of existing synchronous generation, and different dynamic behavior of wind and solar generation. WWSIS-3 evaluates two specific aspects of fundamental frequency system stability: frequency response and transient stability.

  12. Distant Tail Behavior During High Speed Solar Wind Streams and Magnetic Storms

    Science.gov (United States)

    Ho, C. M.; Tsurutani, B. T.

    1997-01-01

    We have examined the ISEE 3 distant tail data during three intense magnetic storms and have identified the tail response to high-speed solar wind streams, interplanetary magnetic clouds, and near-Earth storms.

  13. Solar wind parameters responsible for the plasma injection into the magnetospheric ring current region

    International Nuclear Information System (INIS)

    Bobrov, M.S.

    1977-01-01

    Solar wind effect on the magnetospheric ring-current region has been considered. The correlations with solar wind parameters of the magnitude qsub(o) proportional to the total energy of particles being injected into the magnetospheric ring-current region per one hour are studied statistically and by comparison of time variations. The data on 8 sporadic geomagnetic storms of various intensity, from moderate to very severe one, are used. It is found that qsub(o) correlates not only with the magnitude and the direction of the solar-wind magnetic field component normal to the ecliptic plane, Bsub(z), but also with the variability, sigmasub(B), of the total magnetic-field strength vector. The solar-wind flux velocity ν influences the average storm intensity but the time variations of ν during any individual storm do not correlate with those of qsub(o)

  14. (abstract) The Distant Tail Behavior During High Speed Solar Wind Streams and Magnetic Storms

    Science.gov (United States)

    Ho, C. M.; Tsurutani, B. T.

    1996-01-01

    We have examined the ISEE-3 distant tail data during three intense magnetic storms and have identified the tail response to high speed solar wind streams, interplanetary magnetic clouds, and near-Earth storms.

  15. Diagnostics of the Solar Wind and Global Heliosphere with Lyman-α Emission Measurements

    Science.gov (United States)

    Provornikova, E. P.; Izmodenov, V. V.; Laming, J. M.; Strachan, L.; Wood, B. E.; Katushkina, O. A.; Ko, Y.-K.; Tun Beltran, S.; Chakrabarti, S.

    2018-02-01

    We propose to develop an instrument measuring full sky intensity maps and spectra of interplanetary Lyman-α emission to reveal the global solar wind variability and the nature of the heliosphere and the local interstellar medium.

  16. Vestas Power Plant Solutions Integrating Wind, Solar PV and Energy Storage

    DEFF Research Database (Denmark)

    Petersen, Lennart; Hesselbæk, Bo; Martinez, Antonio

    2018-01-01

    This paper addresses a value proposition and feasible system topologies for hybrid power plant solutions integrating wind, solar PV and energy storage and moreover provides insights into Vestas hybrid power plant projects. Seen from the perspective of a wind power plant developer, these hybrid...... solutions provide a number of benefits that could potentially reduce the Levelized Cost of Energy and enable entrance to new markets for wind power and facilitate the transition to a more sustainable energy mix. First, various system topologies are described in order to distinguish the generic concepts...... for the electrical infrastructure of hybrid power plants. Subsequently, the benefits of combining wind and solar PV power as well as the advantages of combining variable renewable energy sources with energy storage are elaborated. Finally, the world’s first utility-scale hybrid power plant combining wind, solar PV...

  17. Statistical study of chorus wave distributions in the inner magnetosphere using Ae and solar wind parameters

    Science.gov (United States)

    Aryan, Homayon; Yearby, Keith; Balikhin, Michael; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Boynton, Richard

    2014-08-01

    Energetic electrons within the Earth's radiation belts represent a serious hazard to geostationary satellites. The interactions of electrons with chorus waves play an important role in both the acceleration and loss of radiation belt electrons. The common approach is to present model wave distributions in the inner magnetosphere under different values of geomagnetic activity as expressed by the geomagnetic indices. However, it has been shown that only around 50% of geomagnetic storms increase flux of relativistic electrons at geostationary orbit while 20% causes a decrease and the remaining 30% has relatively no effect. This emphasizes the importance of including solar wind parameters such as bulk velocity (V), density (n), flow pressure (P), and the vertical interplanetary magnetic field component (Bz) that are known to be predominately effective in the control of high energy fluxes at the geostationary orbit. Therefore, in the present study the set of parameters of the wave distributions is expanded to include the solar wind parameters in addition to the geomagnetic activity. The present study examines almost 4 years (1 January 2004 to 29 September 2007) of Spatio-Temporal Analysis of Field Fluctuation data from Double Star TC1 combined with geomagnetic indices and solar wind parameters from OMNI database in order to present a comprehensive model of wave magnetic field intensities for the chorus waves as a function of magnetic local time, L shell (L), magnetic latitude (λm), geomagnetic activity, and solar wind parameters. Generally, the results indicate that the intensity of chorus emission is not only dependent upon geomagnetic activity but also dependent on solar wind parameters with velocity and southward interplanetary magnetic field Bs (Bz < 0), evidently the most influential solar wind parameters. The largest peak chorus intensities in the order of 50 pT are observed during active conditions, high solar wind velocities, low solar wind densities, high

  18. Relation between superheating and superacceleration of helium in the solar wind

    International Nuclear Information System (INIS)

    Neugebauer, M.M.; Feldman, W.C.

    1979-01-01

    Solar wind data obtained by the OGO-5 and IMP-6-8 Earth satellites show a positive correlation between the ratio of helium to hydrogen temperatures, Tsub(α)/Tsub(p), and the velocity difference between the two ions, vsub(α)-vsub(p). Although this result disagrees with the Prognoz-1 results reported earlier in this journal, it is consistent with the expected control by Coulomb collisions when the solar-wind density is high. (Auth.)

  19. Solar wind effects on the outer ion coma of Comet Halley

    International Nuclear Information System (INIS)

    Flammer, K.R.

    1987-01-01

    A simple two-dimensional model is developed to examine the composition of the cometary ion coma in the region outside the ionopause which is strongly affected by the solar wind. Two-dimensional ion distributions are obtained assuming a cylindrically symmetric ion coma which accounts for the dynamic effects of the mass-loaded solar wind flow around the cometary ionosphere. The results of this model are discussed in the context of analyzing the GIOTTO ion data

  20. Oblique proton fire hose instability in the expanding solar wind: Hybrid simulations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel M.

    2008-01-01

    Roč. 113, A10 (2008), A10109/1-A10109/9 ISSN 0148-0227 R&D Projects: GA AV ČR IAA300420702; GA AV ČR IAA300420602 Institutional research plan: CEZ:AV0Z30420517; CEZ:AV0Z10030501 Keywords : kinetic instability * fire hose * solar wind * fire hose instabilities * linear analysis * nonlinear evolution * solar wind Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.147, year: 2008

  1. Application of synchronous grid-connected controller in the wind-solar-storage micro grid

    OpenAIRE

    Li, Hua; Ren, Yongfeng; Li, Le; Luo, Zhenpeng

    2016-01-01

    Recently, there has been an increasing interest in using distributed generators (DG) not only to inject power into the grid, but also to enhance the power quality. In this study, a space voltage pulse width modulation (SVPWM) control method is proposed for a synchronous grid-connected controller in a wind-solar-storage micro grid. This method is based on the appropriate topology of the synchronous controller. The wind-solar-storage micro grid is controlled to reconnect to the grid synchronous...

  2. Latitude dependence of the solar wind speed: Influence of the coronal magnetic field geometry

    International Nuclear Information System (INIS)

    Pneuman, G.W.

    1976-01-01

    The dependence of solar wind speed on latitude as influenced by the magnetic field configuration of the inner corona is studied. It is found that in general, a dipolelike field geometry characteristic of a minimum-type corona tends to produce a solar wind speed distribution which increases with heliographic latitude, in accordance with observations. At very high coronal base densities and temperatures, however, this effect is minimal or even inverted. Physically, the field affects the wind speed through its area divergence, a larger divergence resulting in correspondingly lower speeds. During solar minimum, eclipse photographs suggest that the field divergence increases from pole to equator, a characteristic not apparent during solar maximum. Hence we expect the latitudinal increase in speed to be most pronounced at the minimum phase of solar activity

  3. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; hide

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

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

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2009-06-01

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

  5. Polar ionospheric responses to solar wind IMF changes

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2000-06-01

    Full Text Available Auroral and airglow emissions over Eureka (89° CGM during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of the period, Bz was northward and polar arcs were observed. Several overpasses by DMSP satellites during the four day period provided a clear picture of the particle precipitation producing the polar arcs. The spectral character of these events indicated excitation by electrons of average energy 300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV observed and these appeared transitory from the ground optical data. It is noted that polar arcs appear after sudden changes in IMF By, suggesting IMF control over arc initiation. When By is positive there is arc motion from dawn to dusk, while By is negative the motion is consistently dusk to dawn. F-region (anti-sunward convections were monitored through the period from 630.0 nm emissions. The convection speed was low (100-150 m/s when Bz was northward but increased to 500 m/s after Bz turned southward on January 20.Key words: Atmospheric composition and structure (airglow and aurora - Ionosphere (particle precipitation - Magnetospheric Physics (polar cap phenomena

  6. TESTING THE EFFECTS OF EXPANSION ON SOLAR WIND TURBULENCE

    International Nuclear Information System (INIS)

    Vech, Daniel; Chen, Christopher H K

    2016-01-01

    We present a multi-spacecraft approach to test the predictions of recent studies on the effect of solar wind expansion on the radial spectral, variance, and local 3D anisotropies of the turbulence. We found that on small scales (5000–10,000 km) the power levels of the B-trace structure functions do not depend on the sampling direction with respect to the radial suggesting that on this scale the effect of expansion is small possibly due to fast turbulent timescales. On larger scales (110–135 R E ), the fluctuations of the radial magnetic field component are reduced by ∼20% compared to the transverse (perpendicular to radial) ones, which could be due to expansion confining the fluctuations into the plane perpendicular to radial. For the local 3D spectral anisotropy, the B-trace structure functions showed dependence on the sampling direction with respect to radial. The anisotropy in the perpendicular plane is reduced when the increments are taken perpendicular with respect to radial, which could be an effect of expansion.

  7. Magnetic intermittency of solar wind turbulence in the dissipation range

    Science.gov (United States)

    Pei, Zhongtian; He, Jiansen; Tu, Chuanyi; Marsch, Eckart; Wang, Linghua

    2016-04-01

    The feature, nature, and fate of intermittency in the dissipation range are an interesting topic in the solar wind turbulence. We calculate the distribution of flatness for the magnetic field fluctuations as a functionof angle and scale. The flatness distribution shows a "butterfly" pattern, with two wings located at angles parallel/anti-parallel to local mean magnetic field direction and main body located at angles perpendicular to local B0. This "butterfly" pattern illustrates that the flatness profile in (anti-) parallel direction approaches to the maximum value at larger scale and drops faster than that in perpendicular direction. The contours for probability distribution functions at different scales illustrate a "vase" pattern, more clear in parallel direction, which confirms the scale-variation of flatness and indicates the intermittency generation and dissipation. The angular distribution of structure function in the dissipation range shows an anisotropic pattern. The quasi-mono-fractal scaling of structure function in the dissipation range is also illustrated and investigated with the mathematical model for inhomogeneous cascading (extended p-model). Different from the inertial range, the extended p-model for the dissipation range results in approximate uniform fragmentation measure. However, more complete mathematicaland physical model involving both non-uniform cascading and dissipation is needed. The nature of intermittency may be strong structures or large amplitude fluctuations, which may be tested with magnetic helicity. In one case study, we find the heating effect in terms of entropy for large amplitude fluctuations seems to be more obvious than strong structures.

  8. Structures and Intermittency in Small Scales Solar Wind Turbulence

    International Nuclear Information System (INIS)

    Sahraoui, Fouad; Goldstein, Melvyn

    2010-01-01

    Several observations in space plasmas have reported the presence of coherent structures at different plasma scales. Structure formation is believed to result from nonlinear interactions between the plasma modes, which depend strongly on their phase synchronization. Despite this important role of the phases in turbulence, very limited work has been devoted to study the phases as potential tracers of nonlinearities in comparison with the wealth of literature on power spectra of turbulence where phases are totally missed. The reason why the phases are seldom used is probably because they usually appear to be completely mixed (due to their dependence on an arbitrary time origin and to 2π periodicity). To handle the phases properly, a new method based on using surrogate data has been developed recently to detect coherent structures in magnetized plasmas [Sahraoui, PRE, 2008]. Here, we show new applications of the technique to study the nature (weak vs strong, self-similar vs intermittent) of the small scale turbulence in the solar wind using the Cluster observations.

  9. TESTING THE EFFECTS OF EXPANSION ON SOLAR WIND TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Vech, Daniel; Chen, Christopher H K, E-mail: dvech@umich.edu [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-11-20

    We present a multi-spacecraft approach to test the predictions of recent studies on the effect of solar wind expansion on the radial spectral, variance, and local 3D anisotropies of the turbulence. We found that on small scales (5000–10,000 km) the power levels of the B-trace structure functions do not depend on the sampling direction with respect to the radial suggesting that on this scale the effect of expansion is small possibly due to fast turbulent timescales. On larger scales (110–135 R{sub E}), the fluctuations of the radial magnetic field component are reduced by ∼20% compared to the transverse (perpendicular to radial) ones, which could be due to expansion confining the fluctuations into the plane perpendicular to radial. For the local 3D spectral anisotropy, the B-trace structure functions showed dependence on the sampling direction with respect to radial. The anisotropy in the perpendicular plane is reduced when the increments are taken perpendicular with respect to radial, which could be an effect of expansion.

  10. Beam instability of the Z mode in the solar wind

    International Nuclear Information System (INIS)

    Krauss-Varban, D.

    1989-01-01

    The growth rate of the z mode is calculated assuming a cold magnetized background plasma and a tenuous population of hot electrons. For a weak, but nonvanishing, magnetic field the growth rate is shown to coincide with that of the electrostatic Langmuir wave, i.e., the result when the influence of the ambient magnetic field is only retained for the energetic electrons. Considering the case of a beam of hot electrons, we numerically evaluate the expression for the growth rate for several cases of solar wind plasma conditions. Solution of the full 3 x 3 dispersion determinant allows the computation of the growth rate and real frequency shift for arbitrary beam densities and magnetic field strength. The influence of the background magnetic field is discussed, and the apparent polarization of the excited waves is calculated assuming a weak density gradient between source and observer. The effect of the beam density, direction of propagation, and magnetic field on the observable polarization is discussed. copyright American Geophysical Union 1989

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

    Directory of Open Access Journals (Sweden)

    C. Forsyth

    2009-06-01

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

  12. Solar Wind Electron Scattering by Kinetic Instabilities and Whistler Turbulence

    Science.gov (United States)

    Gary, S. P.

    2015-12-01

    The expansion of the solar wind away from the Sun drives electron velocity distributions away from the thermal Maxwellian form, yielding distributions near 1 AU which typically can be characterized as consisting of three anisotropic components: a more dense, relatively cool core, a relatively tenuous , relatively warm halo and a similarly tenuous, warm strahl. Each of these nonthermal components are potential sources of kinetic plasma instabilities; the enhanced waves from each instability can scatter the electrons, acting to reduce the various anisotropies and making their overall velocity distribution more nearly (but not completely) thermal. In contrast, simulations are demonstrating that the forward decay of whistler turbulence can lead to the development of a T||> T_perp electron anisotropy. This presentation will review linear theories of electron-driven kinetic instabilities (following the presentation by Daniel Verscharen at the 2015 SHINE Workshop), and will further consider the modification of electron velocity distributions as obtained from particle-in-cell simulations of such instabilities as well as from the decay of whistler turbulence.

  13. Solar wind energy transfer regions inside the dayside magnetopause

    International Nuclear Information System (INIS)

    Lundin, R.; Dubinin, E.

    1984-01-01

    PROGNOZ-7 high temporal resolution measurements of the ion composition and hot plasma distribution in the dayside high latitude boundary layer near noon have revealed that magnetosheath plasma may penetrate the dayside magnetopause and form high density, high β, magnetosheath-like regions inside the magnetopause. From these measurements it is demonstrated that the magnetosheath injection regions most probably play an important role in transferring solar wind energy into the magnetosphere. The transfer regions are characterized by a strong perpendicular flow towards dawn or dusk (depending on local time) but are also observed to expand rapidly along the boundary field lines. This increased flow component transverse to the local magnetic field corresponds to a predominantly radial electric field of up to several mV m -1 , which indicates that the injected magnetosheath plasma causes an enhanced polarization of the boundary layer. Polarization of the boundary layer can therefore be considered a result of a local MHD-process where magnetosheath plasma excess momentum is converted into electromagnetic energy (electric field), i.e. there is an MHD-generator. It was observed that the boundary layer is charged up to tens of kilovolts, a potential which may be highly variable on e.g. the presence of a momentum exchange by the energy transfer regions. (author)

  14. The solar wind-magentosphere energy coupling and magnetospheric disturbances

    International Nuclear Information System (INIS)

    Akasofu, S.I.

    1980-01-01

    The recent finding of the solar wind-magnetosphere energy coupling function epsilon has advanced significantly our understanding of magnetosphere disturbances. It is shown that the magnetosphere-ionosphere coupling system responds somewhat differently to three different input energy flux levels of epsilon. As epsilon increases from 17 erg s -1 to >10 19 erg s -1 , typical responses of the magnetosphere-ionosphere coupling system are: (1) epsilon 17 erg s -1 : an enhancement of the Ssub(q)sup(p), etc. (2) epsilon approximately 10 18 erg s -1 : substorm onset. (3) 10 18 erg s -1 19 erg s -1 : a typical substorm. (4) epsilon >10 19 erg s -1 : an abnormal growth of the ring current belt, resulting in a magnetospheric storm. It is stressed that the magnetospheric substorm results as a direct response of the magnetosphere to a rise and fall of epsilon above approximately 10 18 erg s -1 , so that it is not caused by a sudden conversion of magnetic energy accumulated prior to substorm onset. The variety of the development of the main phase of geomagnetic storms is also primarily controlled by epsilon. (author)

  15. Bibliometric Analysis of International Collaboration in Wind and Solar Energy

    Directory of Open Access Journals (Sweden)

    Ichiro Sakata

    2013-09-01

    Full Text Available Modern technology is increasingly complex and demands an ever-widening range of knowledge and skills. No single country will possess all the knowledge and skills required for addressing global issues such as climate change. Technology collaboration between leading countries is important to promptly and efficiently address the problem. Previous studies have shown that a high level of collaboration is correlated with high paper productivity. This paper first aims to use objective data and create maps that enable us to see both the distribution of worldwide research competency and the relationship of international collaboration in clean energy research. In the international research network of wind power and solar cell, 4,189 institutions located in 121 countries and 6,600 institutions located in 125 countries are included respectively. This paper discusses various factors that would have an impact on research capability and support strong international relationships. With respect to research capability, governmental policies, stability of governmental commitment, natural conditions and historical and institutional differences have a significant impact on it. For research collaborations, factors such as geographical proximity, international science and technology policy, and developmental stage of technology have been brought to attention. This study demonstrates that bibliometrics is a methodology that is capable of providing a knowledge base that is useful in the development of the international science and technology policy and technological management strategy.

  16. Dependence of Lunar Surface Charging on Solar Wind Plasma Conditions and Solar Irradiation

    Science.gov (United States)

    Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.; Burchill, J. K.; Collier, M. R.; Zimmerman, M. I.; Vondrak, R. R.; Delory, G. T.; Pfaff, R. F.

    2014-01-01

    The surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the pohotoemission of electrons, J(sub p), and the collection of plasma electrons J(sub e) and ions J(sub i). These currents are dependent on the following six parameters: plasma concentration n(sub 0), electron temperature T(sub e), ion temperature T(sub i), bulk flow velocity V, photoemission current at normal incidence J(sub P0), and photo electron temperature T(sub p). Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, T(sub e) is the most important parameter, especially near the terminator, while J(sub P0) and T(sub p) dominate over most of the dayside.

  17. Collective acceleration of protons by the plasma waves in a counterstreaming electron beam

    International Nuclear Information System (INIS)

    Yan, Y.T.

    1987-03-01

    A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the trapping threshold can be dramatically reduced so as to admit the possibility for proton acceleration

  18. Design of Hybrid Solar and Wind Energy Harvester for Fishing Boat

    Science.gov (United States)

    Banjarnahor, D. A.; Hanifan, M.; Budi, E. M.

    2017-07-01

    In southern beach of West Java, Indonesia, there are many villagers live as fishermen. They use small boats for fishing, in one to three days. Therefore, they need a fish preservation system. Fortunately, the area has high potential of solar and wind energy. This paper presents the design of a hybrid solar and wind energy harvester to power a refrigerator in the fishing boat. The refrigerator should keep the fish in 2 - 4 °C. The energy needed is 720 Wh daily. In the area, the daily average wind velocity is 4.27 m/s and the sun irradiation is 672 W/m2. The design combined two 100W solar panels and a 300W wind turbine. The testing showed that the solar panels can harvest 815 - 817 Wh of energy, while the wind turbine can harvest 43 - 62 Wh of energy daily. Therefore, the system can fulfil the energy requirement in fishing boat, although the solar panels were more dominant. To install the wind turbine on the fishing-boat, a computational design had been conducted. The boat hydrostatic dimension was measured to determine its stability condition. To reach a stable equilibrium condition, the wind turbine should be installed no more than 1.7 m of height.

  19. Turbulence-driven coronal heating and improvements to empirical forecasting of the solar wind

    International Nuclear Information System (INIS)

    Woolsey, Lauren N.; Cranmer, Steven R.

    2014-01-01

    Forecasting models of the solar wind often rely on simple parameterizations of the magnetic field that ignore the effects of the full magnetic field geometry. In this paper, we present the results of two solar wind prediction models that consider the full magnetic field profile and include the effects of Alfvén waves on coronal heating and wind acceleration. The one-dimensional magnetohydrodynamic code ZEPHYR self-consistently finds solar wind solutions without the need for empirical heating functions. Another one-dimensional code, introduced in this paper (The Efficient Modified-Parker-Equation-Solving Tool, TEMPEST), can act as a smaller, stand-alone code for use in forecasting pipelines. TEMPEST is written in Python and will become a publicly available library of functions that is easy to adapt and expand. We discuss important relations between the magnetic field profile and properties of the solar wind that can be used to independently validate prediction models. ZEPHYR provides the foundation and calibration for TEMPEST, and ultimately we will use these models to predict observations and explain space weather created by the bulk solar wind. We are able to reproduce with both models the general anticorrelation seen in comparisons of observed wind speed at 1 AU and the flux tube expansion factor. There is significantly less spread than comparing the results of the two models than between ZEPHYR and a traditional flux tube expansion relation. We suggest that the new code, TEMPEST, will become a valuable tool in the forecasting of space weather.

  20. Turbulence-driven coronal heating and improvements to empirical forecasting of the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Woolsey, Lauren N.; Cranmer, Steven R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2014-06-01

    Forecasting models of the solar wind often rely on simple parameterizations of the magnetic field that ignore the effects of the full magnetic field geometry. In this paper, we present the results of two solar wind prediction models that consider the full magnetic field profile and include the effects of Alfvén waves on coronal heating and wind acceleration. The one-dimensional magnetohydrodynamic code ZEPHYR self-consistently finds solar wind solutions without the need for empirical heating functions. Another one-dimensional code, introduced in this paper (The Efficient Modified-Parker-Equation-Solving Tool, TEMPEST), can act as a smaller, stand-alone code for use in forecasting pipelines. TEMPEST is written in Python and will become a publicly available library of functions that is easy to adapt and expand. We discuss important relations between the magnetic field profile and properties of the solar wind that can be used to independently validate prediction models. ZEPHYR provides the foundation and calibration for TEMPEST, and ultimately we will use these models to predict observations and explain space weather created by the bulk solar wind. We are able to reproduce with both models the general anticorrelation seen in comparisons of observed wind speed at 1 AU and the flux tube expansion factor. There is significantly less spread than comparing the results of the two models than between ZEPHYR and a traditional flux tube expansion relation. We suggest that the new code, TEMPEST, will become a valuable tool in the forecasting of space weather.

  1. Early time interaction of lithium ions with the solar wind in the AMPTE mission

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; Goodrich, C.C.; Mankofsky, A.; Papadopoulos, K.

    1986-01-01

    The early time interaction of an artificially injected lithium cloud with the solar wind is simulated with a one-dimensional hybrid code. Simulation results indicate that the lithium cloud presents an obstacle to the solar wind flow, forming a shock-like interaction region. Several notable features are found: (1) The magnetic field is enhanced up to a factor of about 6 followed by a magnetic cavity downstream. (2) Solar wind ions are slowed down inside the lithium cloud, with substantial upstream reflection. (3) Most of the lithium ions gradually pick up the velocity of the solar wind and move downstream. (4) Intense and short-wavelength electric fields exist ahead of the interaction region. (5) Strong electron heating occurs within the lithium clouds. (6) The convection electric field in the in the solar wind is modulated in the interaction region. The simulation results are in remarkable agreement with in situ spacecraft measurements made during lithium releases in the solar wind by the AMPTE (Active magnetospheric Particle Tracer Explorers) Program

  2. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    2002-09-01

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  3. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.

    Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  4. The Potential of hybrid solar-wind electricity generation in Ghana

    International Nuclear Information System (INIS)

    Tibiru, Ayirewura Vitus

    2013-07-01

    In this work the potential of harnessing electricity from solar and wind sources in Ghana is evaluated both quantitatively and qualitatively. In this regard solar, wind and other relevant data were collected (over a period of one year) from various parts of Ghana. Detailed assessment of the capacity or potential of power production from hybrid solar-wind sources is done with the use of empirical mathematical formulae and the PRO VITUS model incorporated in the 'ENERGY X' software. The various characteristics of wind, solar and available energy resources for the five locations over a one year period have been studied too. The annual mean wind speed at a height of 10 m above ground level for five locations namely Accra, Kumasi, Takoradi, Sunyani and Tamale are 2.38 ms"-"1 ± 0.05, 2.39 ms"-"1 ± 0.05, 2.38 ms"-"1 ± 0.06, 2.18 ms"-"1 ± 0.05 and 2.47 ± ms"-"1 respectively and their corresponding annual mean solar radiations are 228.71 Wm"-"2 ± 9.81, 187.69 Wm"-"2 ± 9.60, 236.58 Wm"-"2 ± 10.39, 200.99 Wm"-"2 ± 9.88 and 231.63 Wm"-"2 . Thus, the five sites hold potential for hybrid solar-wind energy exploitation. (au)

  5. Enhancing information for solar and wind energy technology deployment in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ramos Martins, Fernando, E-mail: fernando.martins@inpe.br [Centro de Ciencia do Sistema Terrestre-Instituto Nacisonal de Pesquisas Espaciais (Earth System Center-National Institute for Space Research), P.O. Box 515, 12245-970, Sao Jose dos Campos (Brazil); Pereira, Enio Bueno, E-mail: enio.pereira@inpe.br [Centro de Ciencia do Sistema Terrestre-Instituto Nacisonal de Pesquisas Espaciais (Earth System Center-National Institute for Space Research), P.O. Box 515, 12245-970, Sao Jose dos Campos (Brazil)

    2011-07-15

    Brazil's primary energy matrix is based on more than 47% of renewables, and more than 85% of its electricity is generated by hydro power sources. Despite this large fraction of renewable energy resources, less than 0.3% of the national energy supply comes from solar or wind sources. This paper presents a diagnostic review on the penetration of the solar and wind energy technologies in Brazil. It also includes a survey of the latest government policies and incentives for renewable energies deployment by entrepreneurs, industry and commercial and residential consumers. In addition, the paper analyses how to best meet the requirements for policy support and information technology to boost the deployment of solar technology and wind energy in Brazil. This study was mostly based on results of a widely distributed survey covering key issues, and also by personal interviews carried out with key stakeholders in order to better understand the issues highlighted in the survey responses. The study pointed out some of the main obstacles to effectively promote and improve government policies and actions for investment in solar and wind energy market in Brazil. - Highlights: > Current status on the solar and wind energy deployment in Brazil is presented. > Policy framework required to support solar and wind energy was discussed. > Study was based on responses for consultations with key stakeholders. > Worthiness Index was established to rank the stakeholders outlooks. > Energy price, human resources and tax reductions were indicated as priority.

  6. Enhancing information for solar and wind energy technology deployment in Brazil

    International Nuclear Information System (INIS)

    Ramos Martins, Fernando; Pereira, Enio Bueno

    2011-01-01

    Brazil's primary energy matrix is based on more than 47% of renewables, and more than 85% of its electricity is generated by hydro power sources. Despite this large fraction of renewable energy resources, less than 0.3% of the national energy supply comes from solar or wind sources. This paper presents a diagnostic review on the penetration of the solar and wind energy technologies in Brazil. It also includes a survey of the latest government policies and incentives for renewable energies deployment by entrepreneurs, industry and commercial and residential consumers. In addition, the paper analyses how to best meet the requirements for policy support and information technology to boost the deployment of solar technology and wind energy in Brazil. This study was mostly based on results of a widely distributed survey covering key issues, and also by personal interviews carried out with key stakeholders in order to better understand the issues highlighted in the survey responses. The study pointed out some of the main obstacles to effectively promote and improve government policies and actions for investment in solar and wind energy market in Brazil. - Highlights: → Current status on the solar and wind energy deployment in Brazil is presented. → Policy framework required to support solar and wind energy was discussed. → Study was based on responses for consultations with key stakeholders. → Worthiness Index was established to rank the stakeholders outlooks. → Energy price, human resources and tax reductions were indicated as priority.

  7. OBSERVATIONS OF THE HELIOSHEATH AND SOLAR WIND NEAR THE TERMINATION SHOCK BY VOYAGER 2

    International Nuclear Information System (INIS)

    Burlaga, L. F.; Ness, N. F.; Acuna, M. H.; Richardson, J. D.; Stone, E.; McDonald, F. B.

    2009-01-01

    This paper describes the principal features of 24 hr averages of the magnetic field strength variations B(t) and their relationships to the plasma and energetic particles observed prior to and after the crossing of the termination shock (TS) by Voyager 2 (V2). The solar wind (pre-TS crossing) and heliosheath (post-TS crossing) data extend from day of year (DOY) 1 through 241, 2007 and from 2007 DOY 245 through 2008 DOY 80, respectively. In the solar wind, two merged interaction regions (MIRs) were observed in which the ratio of plasma pressure to magnetic pressure in the solar wind was relatively low. Strong magnetic fields and low values of beta were also observed just prior to its crossing of the TS. The predicted correlation between peaks in the intensity of energetic particles in the solar wind when V2 crossed the heliospheric current sheet from positive to negative magnetic polarity in the solar wind was not observed. In the heliosheath, V2 observed a feature characterized by large enhancements of the density N and the proton temperature T, a small increase in speed V, and a depression in B. The distributions of 24 hr averages of B and beta were approximately log-normal in both the solar wind and the heliosheath. A unipolar region was observed for 73 days in the heliosheath, as the heliospheric current sheet moved toward the equatorial plane to latitudes lower than V2.

  8. SOLAR WIND PROTONS AT 1 AU: TRENDS AND BOUNDS, CONSTRAINTS AND CORRELATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Hellinger, Petr; Trávníček, Pavel M., E-mail: petr.hellinger@asu.cas.cz [Astronomical Institute, AS CR, Bocni II/1401,CZ-14100 Prague (Czech Republic)

    2014-03-20

    The proton temperature anisotropy in the solar wind exhibits apparent bounds which are compatible with the theoretical constraints imposed by temperature-anisotropy-driven kinetic instabilities. Recent statistical analyses based on conditional averaging indicate that near these theoretical constraints the solar wind protons typically have enhanced temperatures and a weaker collisionality. Here we carefully analyze the solar wind data and show that these results are a consequence of superposition of multiple correlations in the solar wind, namely, they mostly result from the correlation between the proton temperature and the solar wind velocity and from the superimposed anti-correlation between the proton temperature anisotropy and the proton parallel beta in the fast solar wind. Colder and more collisional data are distributed around temperature isotropy whereas hotter and less collisional data have a wider range of the temperature anisotropy anti-correlated with the proton parallel beta with signatures of constraints owing to the temperature-anisotropy-driven instabilities. However, most of the hot and weakly collisional data, including the hottest and least collisional ones, lies far from the marginal stability regions. Consequently, we conclude that there is no clear relation between the enhanced temperatures and instability constraints and that the conditional averaging used for these analyses must be used carefully and need to be well tested.

  9. Why fast solar wind originates from slowly expanding coronal flux tubes

    International Nuclear Information System (INIS)

    Wang, Y.M.; Sheeley, N.R. Jr.

    1991-01-01

    Empirical studies indicate that the solar wind speed at earth is inversely correlated with the divergence rate of the coronal magnetic field. It is shown that this result is consistent with simple wind acceleration models involving Alfven waves, provided that the wave energy flux at the coronal base is taken to be roughly constant within open field regions. 9 refs

  10. The Solar Wind: Our Current Understanding and How We Got Here ...

    Indian Academy of Sciences (India)

    The peculiar properties of heavy ions originate close to the Sun in the wind's acceleration ..... where non-MHD kinetic processes are critical. Similarly ... Consider first sunward-moving protons, which we take to have V < 0. Recall that ... We have shown how our thinking about the solar wind has progressed from Parker's.

  11. Effect of wind speed on performance of a solar-pv array

    Science.gov (United States)

    Thousands of solar photovoltaic (PV) arrays have been installed over the past few years, but the effect of wind speed on the predicted performance of PV arrays is not usually considered by installers. An increase in wind speed will cool the PV array, and the electrical power of the PV modules will ...

  12. Spectroscopic Measurements of the Ion Velocity Distribution at the Base of the Fast Solar Wind

    Science.gov (United States)

    Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.; Fletcher, Lyndsay

    2018-03-01

    In situ measurements of the fast solar wind reveal non-thermal distributions of electrons, protons, and minor ions extending from 0.3 au to the heliopause. The physical mechanisms responsible for these non-thermal properties and the location where these properties originate remain open questions. Here, we present spectroscopic evidence, from extreme ultraviolet spectroscopy, that the velocity distribution functions (VDFs) of minor ions are already non-Gaussian at the base of the fast solar wind in a coronal hole, at altitudes of thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent fluctuations or non-uniform wave motions, or (c) some combination of both. These observations provide important empirical constraints for the source region of the fast solar wind and for the theoretical models of the different acceleration, heating, and energy deposition processes therein. To the best of our knowledge, this is the first time that the ion VDF in the fast solar wind has been probed so close to its source region. The findings are also a timely precursor to the upcoming 2018 launch of the Parker Solar Probe, which will provide the closest in situ measurements of the solar wind at approximately 0.04 au (8.5 solar radii).

  13. Use of meteorological information in the risk analysis of a mixed wind farm and solar

    Science.gov (United States)

    Mengelkamp, H.-T.; Bendel, D.

    2010-09-01

    Use of meteorological information in the risk analysis of a mixed wind farm and solar power plant portfolio H.-T. Mengelkamp*,** , D. Bendel** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH The renewable energy industry has rapidly developed during the last two decades and so have the needs for high quality comprehensive meteorological services. It is, however, only recently that international financial institutions bundle wind farms and solar power plants and offer shares in these aggregate portfolios. The monetary value of a mixed wind farm and solar power plant portfolio is determined by legal and technical aspects, the expected annual energy production of each wind farm and solar power plant and the associated uncertainty of the energy yield estimation or the investment risk. Building an aggregate portfolio will reduce the overall uncertainty through diversification in contrast to the single wind farm/solar power plant energy yield uncertainty. This is similar to equity funds based on a variety of companies or products. Meteorological aspects contribute to the diversification in various ways. There is the uncertainty in the estimation of the expected long-term mean energy production of the wind and solar power plants. Different components of uncertainty have to be considered depending on whether the power plant is already in operation or in the planning phase. The uncertainty related to a wind farm in the planning phase comprises the methodology of the wind potential estimation and the uncertainty of the site specific wind turbine power curve as well as the uncertainty of the wind farm effect calculation. The uncertainty related to a solar power plant in the pre-operational phase comprises the uncertainty of the radiation data base and that of the performance curve. The long-term mean annual energy yield of operational wind farms and solar power plants is estimated on the basis of the actual energy production and it

  14. Do In Situ Observations Contain Signatures of Intermittent Fast Solar Wind Acceleration?

    Science.gov (United States)

    Matteini, L.; Horbury, T. S.; Stansby, D.

    2017-12-01

    Disentangling local plasma properties and Solar origin structures in in situ data is a crucial aspect for the understanding of solar wind acceleration and evolution. This is particularly challenging at 1 AU and beyond, where structures of various origin have had time to interact and merge, smoothing out their main characteristics. Observations of more pristine plasma closer to the Sun are therefore needed. In preparation of the forthcoming Solar Orbiter and Parker Solar Probe missions, Helios observations as close as to 0.3 AU - although old, not yet fully exploited - can be used to test our expectations and make new predictions. Recent observations (Matteini et al. 2014, 2015) have outlined the presence of intense (up to 1000km/s) and short-living velocity peaks that ubiquitously characterize the typical profile of the fast solar wind at 0.3 AU, suggesting that these features could be remnants of processes occurring in the Solar atmosphere and a signature of intermittent solar wind acceleration from coronal holes. We discuss results about statistics of these events, characterizing their physical properties and trying to link them with typical Solar temporal and spatial scales. Finally we also discuss how these velocity peaks will likely affect the future in situ exploration of the inner heliosphere by Solar Orbiter and the Parker Solar Probe.

  15. Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements

    DEFF Research Database (Denmark)

    Laundal, K. M.; Finlay, C. C.; Olsen, N.

    2018-01-01

    the ionosphere with the magnetosphere. The model provides ionospheric current values at any location as continuous functions of solar wind speed, interplanetary magnetic field (IMF), dipole tilt angle, and the F10.7 index of solar flux. Geometric distortions due to variations in the Earth's main magnetic field...

  16. OPERATING THE OIL PRODUCTION FACILITY WITH SOLAR AND WIND GENERATOR

    Directory of Open Access Journals (Sweden)

    Marius STAN

    2017-05-01

    Full Text Available In this paper we present an analysis of theoretical concepts very common nowadays, photovoltaic and wind turbines, but also a practical part where I presented a hybrid (photovoltaic-wind to power a pump extraction cavitation progressive.

  17. Integrating Wind And Solar With Hydrogen Producing Fuel Cells

    NARCIS (Netherlands)

    Hemmes, K.

    2007-01-01

    The often proposed solution for the fluctuating wind energy supply is the conversion of the surplus of wind energy into hydrogen by means of electrolysis. In this paper a patented alternative is proposed consisting of the integration of wind turbines with internal reforming fuel-cells, capable of

  18. Global Solar Magnetic Field Organization in the Outer Corona: Influence on the Solar Wind Speed and Mass Flux Over the Cycle

    Science.gov (United States)

    Réville, Victor; Brun, Allan Sacha

    2017-11-01

    The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-year solar cycle. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 {R}⊙ , the source surface radius that approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface. We demonstrate this using 3D global magnetohydrodynamic (MHD) simulations of the solar corona, constrained by surface magnetograms over half a solar cycle (1989-2001). A self-consistent expansion beyond the solar wind critical point (even up to 10 {R}⊙ ) makes our model comply with observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun, and that the mass flux is mostly independent of the terminal wind speed. We also show that near activity minimum, the expansion in the higher corona has more influence on the wind speed than the expansion below 2.5 {R}⊙ .

  19. On krypton isotopic abundances in the sun and in the solar wind

    Science.gov (United States)

    Marti, K.

    1980-01-01

    The Kr isotopic systematics in the meteorite Pesyanoe which is known to contain solar-type gases, are reported. Discrepancies in the isotopic data of fractions released at stepwise increasing temperatures cannot be reconciled with spallation Kr components, although spallation effects are significant. Fractionation mechanisms on the parent body and in the solar wind source region are considered and the implications for solar abundances discussed.

  20. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    Science.gov (United States)

    Gold, R. E.; Dodson-Prince, H. W.; Hedeman, E. R.; Roelof, E. C.

    1982-01-01

    Solar and interplanetary data are examined, taking into account the identification of the heliographic longitudes of the coronal source regions of high speed solar wind (SW) streams by Nolte and Roelof (1973). Nolte and Roelof have 'mapped' the velocities measured near earth back to the sun using the approximation of constant radial velocity. The 'Carrington carpet' for rotations 1597-1616 is shown in a graph. Coronal sources of high speed streams appear in the form of solid black areas. The contours of the stream sources are laid on 'evolutionary charts' of solar active region histories for the Southern and Northern Hemispheres. Questions regarding the interplay of active regions and solar wind are investigated, giving attention to developments during the years 1973, 1974, and 1975.

  1. Energy principle for excitations in plasmas with counterstreaming electron flows

    Science.gov (United States)

    Kumar, Atul; Shukla, Chandrasekhar; Das, Amita; Kaw, Predhiman

    2018-05-01

    A relativistic electron beam propagating through plasma induces a return electron current in the system. Such a system of interpenetrating forward and return electron current is susceptible to a host of instabilities. The physics of such instabilities underlies the conversion of the flow kinetic energy to the electromagnetic field energy. Keeping this in view, an energy principle analysis has been enunciated in this paper. Such analyses have been widely utilized earlier in the context of conducting fluids described by MHD model [I. B. Bernstein et al., Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 244(1236), 17-40 (1958)]. Lately, such an approach has been employed for the electrostatic two stream instability for the electron beam plasma system [C. N. Lashmore-Davies, Physics of Plasmas 14(9), 092101 (2007)]. In contrast, it has been shown here that even purely growing mode like Weibel/current filamentation instability for the electron beam plasma system is amenable to such a treatment. The treatment provides an understanding of the energetics associated with the growing mode. The growth rate expression has also been obtained from it. Furthermore, it has been conclusively demonstrated in this paper that for identical values of S4=∑αn0 αv0α 2/n0γ0 α, the growth rate is higher when the counterstreaming beams are symmetric (i.e. S3 = ∑αn0αv 0α/n0γ0α = 0) compared to the case when the two beams are asymmetric (i.e. when S3 is finite). Here, v 0α, n0α and γ0α are the equilibrium velocity, electron density and the relativistic factor for the electron species `α' respectively and n0 = ∑αn0α is the total electron density. Particle - In - Cell simulations have been employed to show that the saturated amplitude of the field energy is also higher in the symmetric case.

  2. Opportunities for wind and solar to displace coal and associated health impacts in Texas

    Science.gov (United States)

    Cohan, D. S.; Strasert, B.; Slusarewicz, J.

    2017-12-01

    Texas uses more coal for power production than any other state, but also leads the nation in wind power while lagging in solar. Many analysts expect that more than half of coal power plants may close within the next decade, unable to compete with cheaper natural gas and renewable electricity. To what extent could displacing coal with wind and solar yield benefits for air quality, health, and climate? Here, we present modeling of the ozone, particulate matter, and associated health impacts of each of 15 coal power plants in Texas, using the CAMx model for air quality and BenMAP for health effects. We show that health impacts from unscrubbed coal plants near urban areas can be an order of magnitude larger than some other facilities. We then analyze the temporal patterns of generation that could be obtained from solar and wind farms in various regions of Texas that could displace these coal plants. We find that winds along the southern Gulf coast of Texas exhibit strikingly different temporal patterns than in west Texas, peaking on summer afternoons rather than winter nights. Thus, wind farms from the two regions along with solar farms could provide complementary sources of power to displace coal. We quantify several metrics to characterize the extent to which wind and solar farms in different regions provide complementary sources of power that can reliably displace traditional sources of electricity.

  3. Janus: Graphical Software for Analyzing In-Situ Measurements of Solar-Wind Ions

    Science.gov (United States)

    Maruca, B.; Stevens, M. L.; Kasper, J. C.; Korreck, K. E.

    2016-12-01

    In-situ observations of solar-wind ions provide tremendous insights into the physics of space plasmas. Instrument on spacecraft measure distributions of ion energies, which can be processed into scientifically useful data (e.g., values for ion densities and temperatures). This analysis requires a strong, technical understanding of the instrument, so it has traditionally been carried out by the instrument teams using automated software that they had developed for that purpose. The automated routines are optimized for typical solar-wind conditions, so they can fail to capture the complex (and scientifically interesting) microphysics of transient solar-wind - such as coronal mass ejections (CME's) and co-rotating interaction regions (CIR's) - which are often better analyzed manually.This presentation reports on the ongoing development of Janus, a new software package for processing in-situ measurement of solar-wind ions. Janus will provide user with an easy-to-use graphical user interface (GUI) for carrying out highly customized analyses. Transparent to the user, Janus will automatically handle the most technical tasks (e.g., the retrieval and calibration of measurements). For the first time, users with only limited knowledge about the instruments (e.g., non-instrumentalists and students) will be able to easily process measurements of solar-wind ions. Version 1 of Janus focuses specifically on such measurements from the Wind spacecraft's Faraday Cups and is slated for public release in time for this presentation.

  4. Development of Chemical and Mechanical Cleaning Procedures for Genesis Solar Wind Samples

    Science.gov (United States)

    Schmeling, M.; Jurewicz, A. J. G.; Gonzalez, C.; Allums, K. K.; Allton, J. H.

    2018-01-01

    The Genesis mission was the only mission returning pristine solar material to Earth since the Apollo program. Unfortunately, the return of the spacecraft on September 8, 2004 resulted in a crash landing shattering the solar wind collectors into smaller fragments and exposing them to desert soil and other debris. Thorough surface cleaning is required for almost all fragments to allow for subsequent analysis of solar wind material embedded within. However, each collector fragment calls for an individual cleaning approach, as contamination not only varies by collector material but also by sample itself.

  5. Response of Earth and Venus ionospheres to corotating solar wind stream of 3 July 1979

    International Nuclear Information System (INIS)

    Taylor, H.A. Jr.

    1985-01-01

    Corotating solar wind streams emanating from stable coronal structures provide an unique opportunity to compare the response of planetary ionospheres to the energy conveyed in the streams. For recurrent solar conditions the 'signal' propagating outward along spiral paths in interplanetary space can at times exhibit rather similar content at quite different downstream locations in the ecliptic plane. Using solar wind measurements from plasma detectors on ISEE-3, Pioneer Venus Orbiter (PVO) and Helios-A, as well as in-situ ion composition measurements from Bennett Ion Mass Spectrometers on the Atmosphere Explorer-E and PVO spacecraft, corotating stream interactions are examined at Earth and Venus. (Auth.)

  6. Recent Optical and SEM Characterization of Genesis Solar Wind Concentrator Diamond on Silicon Collector

    Science.gov (United States)

    Allton, Judith H.; Rodriquez, M. C.; Burkett, P. J.; Ross, D. K.; Gonzalez, C. P.; McNamara, K. M.

    2013-01-01

    One of the 4 Genesis solar wind concentrator collectors was a silicon substrate coated with diamond-like carbon (DLC) in which to capture solar wind. This material was designed for analysis of solar nitrogen and noble gases [1, 2]. This particular collector fractured during landing, but about 80% of the surface was recovered, including a large piece which was subdivided in 2012 [3, 4, 5]. The optical and SEM imaging and analysis described below supports the subdivision and allocation of the diamond-on-silicon (DOS) concentrator collector.

  7. The S-Web Model for the Sources of the Slow Solar Wind

    Science.gov (United States)

    Antiochos, Spiro K.; Karpen, Judith T.; DeVore, C. Richard

    2012-01-01

    Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind has large angular width, up to 60 degrees, suggesting that its source extends far from the open-closed boundary. We describe a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices (the S-Web) and quasi-separatrix layers in the heliosphere. We discuss the dynamics of the S-Web model and its implications for present observations and for the upcoming observations from Solar Orbiter and Solar Probe Plus.

  8. Comparison of Solar and Wind Power Output and Correlation with Real-Time Pricing

    Science.gov (United States)

    Hoepfl, Kathryn E.; Compaan, Alvin D.; Solocha, Andrew

    2011-03-01

    This study presents a method that can be used to determine the least volatile power output of a wind and solar hybrid energy system in which wind and solar systems have the same peak power. Hourly data for wind and PV systems in Northwest Ohio are used to show that a combination of both types of sustainable energy sources produces a more stable power output and would be more valuable to the grid than either individually. This method could be used to determine the ideal ratio in any part of the country and should help convince electric utility companies to bring more renewable generation online. This study also looks at real-time market pricing and how each system (solar, wind, and hybrid) correlates with 2009 hourly pricing from the Midwest Interconnect. KEH acknowledges support from the NSF-REU grant PHY-1004649 to the Univ. of Toledo and Garland Energy Systems/Ohio Department of Development.

  9. Charge state evolution in the solar wind. III. Model comparison with observations

    Energy Technology Data Exchange (ETDEWEB)

    Landi, E.; Oran, R.; Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.; Van der Holst, B. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2014-08-01

    We test three theoretical models of the fast solar wind with a set of remote sensing observations and in-situ measurements taken during the minimum of solar cycle 23. First, the model electron density and temperature are compared to SOHO/SUMER spectroscopic measurements. Second, the model electron density, temperature, and wind speed are used to predict the charge state evolution of the wind plasma from the source regions to the freeze-in point. Frozen-in charge states are compared with Ulysses/SWICS measurements at 1 AU, while charge states close to the Sun are combined with the CHIANTI spectral code to calculate the intensities of selected spectral lines, to be compared with SOHO/SUMER observations in the north polar coronal hole. We find that none of the theoretical models are able to completely reproduce all observations; namely, all of them underestimate the charge state distribution of the solar wind everywhere, although the levels of disagreement vary from model to model. We discuss possible causes of the disagreement, namely, uncertainties in the calculation of the charge state evolution and of line intensities, in the atomic data, and in the assumptions on the wind plasma conditions. Last, we discuss the scenario where the wind is accelerated from a region located in the solar corona rather than in the chromosphere as assumed in the three theoretical models, and find that a wind originating from the corona is in much closer agreement with observations.

  10. Charge state evolution in the solar wind. III. Model comparison with observations

    International Nuclear Information System (INIS)

    Landi, E.; Oran, R.; Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.; Van der Holst, B.

    2014-01-01

    We test three theoretical models of the fast solar wind with a set of remote sensing observations and in-situ measurements taken during the minimum of solar cycle 23. First, the model electron density and temperature are compared to SOHO/SUMER spectroscopic measurements. Second, the model electron density, temperature, and wind speed are used to predict the charge state evolution of the wind plasma from the source regions to the freeze-in point. Frozen-in charge states are compared with Ulysses/SWICS measurements at 1 AU, while charge states close to the Sun are combined with the CHIANTI spectral code to calculate the intensities of selected spectral lines, to be compared with SOHO/SUMER observations in the north polar coronal hole. We find that none of the theoretical models are able to completely reproduce all observations; namely, all of them underestimate the charge state distribution of the solar wind everywhere, although the levels of disagreement vary from model to model. We discuss possible causes of the disagreement, namely, uncertainties in the calculation of the charge state evolution and of line intensities, in the atomic data, and in the assumptions on the wind plasma conditions. Last, we discuss the scenario where the wind is accelerated from a region located in the solar corona rather than in the chromosphere as assumed in the three theoretical models, and find that a wind originating from the corona is in much closer agreement with observations.

  11. Turbulence in the solar wind: spectra from Voyager 2 data at 5 AU

    International Nuclear Information System (INIS)

    Fraternale, F; Gallana, L; Iovieno, M; Tordella, D; Opher, M; Richardson, J D

    2016-01-01

    Fluctuations in the flow velocity and magnetic fields are ubiquitous in the Solar System. These fluctuations are turbulent, in the sense that they are disordered and span a broad range of scales in both space and time. The study of solar wind turbulence is motivated by a number of factors all keys to the understanding of the Solar Wind origin and thermodynamics. The solar wind spectral properties are far from uniformity and evolve with the increasing distance from the sun. Most of the available spectra of solar wind turbulence were computed at 1 astronomical unit, while accurate spectra on wide frequency ranges at larger distances are still few. In this paper we consider solar wind spectra derived from the data recorded by the Voyager 2 mission during 1979 at about 5 AU from the sun. Voyager 2 data are an incomplete time series with a voids/signal ratio that typically increases as the spacecraft moves away from the sun (45% missing data in 1979), making the analysis challenging. In order to estimate the uncertainty of the spectral slopes, different methods are tested on synthetic turbulence signals with the same gap distribution as V2 data. Spectra of all variables show a power law scaling with exponents between −2.1 and −1.1, depending on frequency subranges. Probability density functions (PDFs) and correlations indicate that the flow has a significant intermittency. (invited comment)

  12. An analytical investigation: Effect of solar wind on lunar photoelectron sheath

    Science.gov (United States)

    Mishra, S. K.; Misra, Shikha

    2018-02-01

    The formation of a photoelectron sheath over the lunar surface and subsequent dust levitation, under the influence of solar wind plasma and continuous solar radiation, has been analytically investigated. The photoelectron sheath characteristics have been evaluated using the Poisson equation configured with population density contributions from half Fermi-Dirac distribution of the photoemitted electrons and simplified Maxwellian statistics of solar wind plasma; as a consequence, altitude profiles for electric potential, electric field, and population density within the photoelectron sheath have been derived. The expression for the accretion rate of sheath electrons over the levitated spherical particles using anisotropic photoelectron flux has been derived, which has been further utilized to characterize the charging of levitating fine particles in the lunar sheath along with other constituent photoemission and solar wind fluxes. This estimate of particle charge has been further manifested with lunar sheath characteristics to evaluate the altitude profile of the particle size exhibiting levitation. The inclusion of solar wind flux into analysis is noticed to reduce the sheath span and altitude of the particle levitation; the dependence of the sheath structure and particle levitation on the solar wind plasma parameters has been discussed and graphically presented.

  13. A Systematic Search for Solar Wind Charge Exchange Emission from the Earth's Exosphere with Suzaku

    Science.gov (United States)

    Ishi, D.; Ishikawa, K.; Ezoe, Y.; Ohashi, T.; Miyoshi, Y.; Terada, N.

    2017-10-01

    We report on a systematic search of all the Suzaku archival data covering from 2005 August to 2015 May for geocoronal Solar Wind Charge eXchange (SWCX). In the vicinity of Earth, solar wind ions strip an electron from Earth's exospheric neutrals, emitting X-ray photons (e.g., Snowden et al. 1997). The X-ray flux of this geocoronal SWCX can change depending on solar wind condition and line of sight direction. Although it is an immediate background for all the X-ray astronomy observations, the X-ray flux prediction and the dependence on the observational conditions are not clear. Using the X-ray Imaging Spectrometer onboard Suzaku which has one of the highest sensitivities to the geocoronal SWCX, we searched the data for time variation of soft X-ray background. We then checked the solar wind proton flux taken with the WIND satellite and compared it with X-ray light curve. We also analyzed X-ray spectra and fitted them with a charge exchange emission line model constructed by Bodewits et al. (2007). Among 3055 data sets, 90 data showed SWCX features. The event rate seems to correlate with solar activity, while the distribution of SWCX events plotted in the solar magnetic coordinate system was relatively uniform.

  14. Polar ionospheric responses to solar wind IMF changes

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    Full Text Available Auroral and airglow emissions over Eureka (89° CGM during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of the period, Bz was northward and polar arcs were observed. Several overpasses by DMSP satellites during the four day period provided a clear picture of the particle precipitation producing the polar arcs. The spectral character of these events indicated excitation by electrons of average energy 300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV observed and these appeared transitory from the ground optical data. It is noted that polar arcs appear after sudden changes in IMF By, suggesting IMF control over arc initiation. When By is positive there is arc motion from dawn to dusk, while By is negative the motion is consistently dusk to dawn. F-region (anti-sunward convections were monitored through the period from 630.0 nm emissions. The convection speed was low (100-150 m/s when Bz was northward but increased to 500 m/s after Bz turned southward on January 20.

    Key words: Atmospheric composition and structure (airglow and aurora - Ionosphere (particle precipitation - Magnetospheric Physics (polar cap phenomena

  15. Wind effects on convective heat loss from a cavity receiver for a parabolic concentrating solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Ma, R.Y. [California State Polytechnic Univ., Pomoma, CA (United States). Dept. of Mechanical Engineering

    1993-09-01

    Tests were performed to determine the convective heat loss characteristics of a cavity receiver for a parabolid dish concentrating solar collector for various tilt angles and wind speeds of 0-24 mph. Natural (no wind) convective heat loss from the receiver is the highest for a horizontal receiver orientation and negligible with the reveler facing straight down. Convection from the receiver is substantially increased by the presence of side-on wind for all receiver tilt angles. For head-on wind, convective heat loss with the receiver facing straight down is approximately the same as that for side-on wind. Overall it was found that for wind speeds of 20--24 mph, convective heat loss from the receiver can be as much as three times that occurring without wind.

  16. QUANTIFYING THE ANISOTROPY AND SOLAR CYCLE DEPENDENCE OF '1/f' SOLAR WIND FLUCTUATIONS OBSERVED BY ADVANCED COMPOSITION EXPLORER

    International Nuclear Information System (INIS)

    Nicol, R. M.; Chapman, S. C.; Dendy, R. O.

    2009-01-01

    The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range (IR) of turbulent fluctuations at higher frequencies and a '1/f' like region at lower frequencies. In the ecliptic plane at ∼1 AU, this break occurs approximately at timescales of a few hours and is observed in the power spectra of components of velocity and magnetic field. The '1/f' energy range is of more direct coronal origin than the IR, and carries signatures of the complex magnetic field structure of the solar corona, and of footpoint stirring in the solar photosphere. To quantify the scaling properties we use generic statistical methods such as generalized structure functions and probability density functions (PDFs), focusing on solar cycle dependence and on anisotropy with respect to the background magnetic field. We present structure function analysis of magnetic and velocity field fluctuations, using a novel technique to decompose the fluctuations into directions parallel and perpendicular to the mean local background magnetic field. Whilst the magnetic field is close to '1/f', we show that the velocity field is '1/f α ' with α ≠ 1. For the velocity, the value of α varies between parallel and perpendicular fluctuations and with the solar cycle. There is also variation in α with solar wind speed. We have examined the PDFs in the fast, quiet solar wind and intriguingly, whilst parallel and perpendicular are distinct, both the B field and velocity show the same PDF of their perpendicular fluctuations, which is close to gamma or inverse Gumbel. These results point to distinct physical processes in the corona and to their mapping out into the solar wind. The scaling exponents obtained constrain the models for these processes.

  17. Non-Extensive Statistical Analysis of Solar Wind Electric, Magnetic Fields and Solar Energetic Particle time series.

    Science.gov (United States)

    Pavlos, G. P.; Malandraki, O.; Khabarova, O.; Livadiotis, G.; Pavlos, E.; Karakatsanis, L. P.; Iliopoulos, A. C.; Parisis, K.

    2017-12-01

    In this work we study the non-extensivity of Solar Wind space plasma by using electric-magnetic field data obtained by in situ spacecraft observations at different dynamical states of solar wind system especially in interplanetary coronal mass ejections (ICMEs), Interplanetary shocks, magnetic islands, or near the Earth Bow shock. Especially, we study the energetic particle non extensive fractional acceleration mechanism producing kappa distributions as well as the intermittent turbulence mechanism producing multifractal structures related with the Tsallis q-entropy principle. We present some new and significant results concerning the dynamics of ICMEs observed in the near Earth at L1 solar wind environment, as well as its effect in Earth's magnetosphere as well as magnetic islands. In-situ measurements of energetic particles at L1 are analyzed, in response to major solar eruptive events at the Sun (intense flares, fast CMEs). The statistical characteristics are obtained and compared for the Solar Energetic Particles (SEPs) originating at the Sun, the energetic particle enhancements associated with local acceleration during the CME-driven shock passage over the spacecraft (Energetic Particle Enhancements, ESPs) as well as the energetic particle signatures observed during the passage of the ICME. The results are referred to Tsallis non-extensive statistics and in particular to the estimation of Tsallis q-triplet, (qstat, qsen, qrel) of electric-magnetic field and the kappa distributions of solar energetic particles time series of the ICME, magnetic islands, resulting from the solar eruptive activity or the internal Solar Wind dynamics. Our results reveal significant differences in statistical and dynamical features, indicating important variations of the magnetic field dynamics both in time and space domains during the shock event, in terms of rate of entropy production, relaxation dynamics and non-equilibrium meta-stable stationary states.

  18. Indirect solar wind geothermal: Alternative energy sources 4, volume 4

    Science.gov (United States)

    Veziroglu, T. N.

    The utilities are obliged to provide electricity in a reliable and cost effective manner. Some unique problems posed by large scale wind turbines as an electricity source have to be considered. A value model is presented which is based upon the fuel displacement capability and the capacity displacement capability of wind turbines. The amount of fossil fuels which is saved by wind turbines depends on the forecasted wind power output, the actual power output fluctuations of the wind turbines and on system operation. The highly controversial capacity credit of wind turbines is discussed under the aspect of system reliability. It is shown that calculations of the capacity credit should be based upon detailed investigations with regard to the time dependence of the hourly wind power output.

  19. Search for the sources of the solar wind in the 9.1 cm brightness temperature

    International Nuclear Information System (INIS)

    George, R.G.

    1975-01-01

    The sources of solar wind streams have been the object of intensive research for many years, but the various ideas of where and how streams originate on the sun are still incomplete and contradictory. The present study is an attempt to find the solar wind sources by mathematically approximating the 9.1 cm brightness temperature which would be expected at the foot of spacecraft-measured solar wind streams and by then comparing it with actual radio brightness temperature measurements. Several significant results were found from an analysis of the correlation results. Most plasma emanating from the sun was found to come from high solar latitudes and to deviate significantly from the normally expected east-west path in the low corona. Magnetic channelng causes correlation studies to fail when the sun's magnetic configuration is unstable. The travel time of the plasma from the sun's 9.1 cm emission level to the earth is often more than a month

  20. The interactions of the HELIOS probe with the solar wind plasma

    International Nuclear Information System (INIS)

    Voigt, G.H.; Isensee, U.; Maassberg, H.

    1981-08-01

    HELIOS solar probe disturbs the solar wind plasma in the near vicinity. Around the probe, a space charge cloud is formed due to strong photoelectron emission and fade out of solar wind particles. The conducting and isolating parts of the surface are differently charged. These effects result in a very complex potential structure in the vicinity of the probe and on the surface. The interactions of the HELIOS probe with the solar wind plasma are described by models based on kinetic theory of plasma. The combination of these models yields an entire and consistent representation of the spacecraft charging and the potential structure. Electron spectra measured by plasma experiment E1 are analysed and compared with results of the theoretical models. (orig.) [de

  1. Long-term solar wind electron variations between 1971 and 1978

    International Nuclear Information System (INIS)

    Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

    1979-01-01

    Imp solar wind electron data measured between 1971 and 1978 were studied with the aim of determining long-term variations near the earth. Two separate sets of parameter variations were observed: (1) in 1976--1977 the solar wind density, the electron temperature, and the interplanetary electrostatic potential were all enhanced, and (2) the halo density and associated electron parameters were all depressed during a 1 1/2-year period centered on the last 6 months of 1976. Although interpretation of these results in terms of corresponding coronal and interplanetary variations is not unique, it may be significant that measured solar wind parameters near the minimum of solar cycle 20 agree better with the Hartle-Sturrock model of the coronal expansion than they do during other epochs

  2. Assessing the Structural, Driver and Economic Impacts of Traffic Pole Mounted Wind Power Generator and Solar Panel Hybrid System

    Science.gov (United States)

    2012-06-01

    This project evaluates the physical and economic feasibility of using existing traffic infrastructure to mount wind power : generators. Some possible places to mount a light weight wind generator and solar panel hybrid system are: i) Traffic : signal...

  3. Autocorrelation Study of Solar Wind Plasma and IMF Properties as Measured by the MAVEN Spacecraft

    Science.gov (United States)

    Marquette, Melissa L.; Lillis, Robert J.; Halekas, J. S.; Luhmann, J. G.; Gruesbeck, J. R.; Espley, J. R.

    2018-04-01

    It has long been a goal of the heliophysics community to understand solar wind variability at heliocentric distances other than 1 AU, especially at ˜1.5 AU due to not only the steepening of solar wind stream interactions outside 1 AU but also the number of missions available there to measure it. In this study, we use 35 months of solar wind and interplanetary magnetic field (IMF) data taken at Mars by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to conduct an autocorrelation analysis of the solar wind speed, density, and dynamic pressure, which is derived from the speed and density, as well as the IMF strength and orientation. We found that the solar wind speed is coherent, that is, has an autocorrelation coefficient above 1/e, over roughly 56 hr, while the density and pressure are coherent over smaller intervals of roughly 25 and 20 hr, respectively, and that the IMF strength is coherent over time intervals of approximately 20 hr, while the cone and clock angles are considerably less steady but still somewhat coherent up to time lags of roughly 16 hr. We also found that when the speed, density, pressure, or IMF strength is higher than average, the solar wind or IMF becomes uncorrelated more quickly, while when they are below average, it tends to be steadier. This analysis allows us to make estimates of the values of solar wind plasma and IMF parameters when they are not directly measured and provide an approximation of the error associated with that estimate.

  4. The distribution of waves in the inner magnetosphere as a function of solar wind parameters

    Science.gov (United States)

    Aryan, Homayon; Balikhin, Michael A.; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Yearby, Keith

    Energetic electrons within the Earth’s radiation belts represent a serious hazard to geostationary satellites. The interactions of electrons with chorus waves play an important role in both the acceleration and loss of radiation belt electrons. Studies of the evolution of energetic electron fluxes rely heavily on numerical codes in order to model energy and pitch angle diffusion due to electron interaction with plasma waves in the frame of quasilinear approximation. Application of these codes requires knowledge of statistical wave models to present wave distributions in the magnetosphere. A number of such models are based on CRESS, Cluster, THEMIS and other mission data. These models present wave distributions as a function of L-shell, magnetic local time, magnetic latitude and geomagnetic activity expressed by geomagnetic indices (Kp or Ae). However, it has been shown by G. Reeves and co-authors that only 50% of geomagnetic storms increase flux of relativistic electrons at GEO while 20% cause a decrease. This emphasizes the importance of including solar wind parameters in addition to geomagnetic indices. The present study examines almost four years (01, January, 2004 to 29, September, 2007) of STAFF (Spatio-Temporal Analysis of Field Fluctuation) data from Double Star TC1 combined with geomagnetic indices and solar wind parameters from OMNI database in order to present a comprehensive model of chorus wave intensities as a function of L-shell, magnetic local time, magnetic latitude, geomagnetic indices and solar wind parameters. The results show that chorus emission is not only sub-storm dependent but also dependent upon solar wind parameters with solar wind velocity evidently the most influential solar wind parameter. The largest peak intensities are observed for lower band chorus during active conditions, high solar wind velocity, low density and high pressure.

  5. An illustrative note on the system price effect of wind and solar power. The German case

    Energy Technology Data Exchange (ETDEWEB)

    Jaegemann, Cosima

    2014-07-15

    Exposing wind and solar power to the market price signal allows for cost-efficient investment decisions, as it incentivizes investors to account for the marginal value (MV{sup el}) of renewable energy technologies. As shown by Lamont (2008), the MV{sup el} of wind and solar power units depends on their penetration level. More specifically, the MV el of wind and solar power units is a function of the respective unit's capacity factor and the covariance between its generation profile and the system marginal costs. The latter component of the MV{sup el} (i.e., the covariance) is found to decline as the wind and solar power penetration increases, displacing dispatchable power plants with higher short-run marginal costs of power production and thus reducing the system marginal costs in all generation hours. This so called 'system price effect' is analyzed in more detail in this paper. The analysis complements the work Lamont (2008) in two regards. First of all, an alternative expression for the MV{sup el} of wind and solar power units is derived, which shows that the MV{sup el} of fluctuating renewable energy technologies depends not only on their own penetration level but also on a variety of other parameters that are specific to the electricity system. Second, based on historical wholesale prices and wind and solar power generation data for Germany, a numerical 'ceteris paribus' example for Germany is presented which illustrates that the system price effect is already highly relevant for both wind and solar power generation in Germany.

  6. A Study of the Solar Wind-Magnetosphere Coupling Using Neural Networks

    Science.gov (United States)

    Wu, Jian-Guo; Lundstedt, Henrik

    1996-12-01

    The interaction between solar wind plasma and interplanetary magnetic field (IMF) and Earth's magnetosphere induces geomagnetic activity. Geomagnetic storms can cause many adverse effects on technical systems in space and on the Earth. It is therefore of great significance to accurately predict geomagnetic activity so as to minimize the amount of disruption to these operational systems and to allow them to work as efficiently as possible. Dynamic neural networks are powerful in modeling the dynamics encoded in time series of data. In this study, we use partially recurrent neural networks to study the solar wind-magnetosphere coupling by predicting geomagnetic storms (as measured by the Dstindex) from solar wind measurements. The solar wind, the IMF and the geomagnetic index Dst data are hourly averaged and read from the National Space Science Data Center's OMNI database. We selected these data from the period 1963 to 1992, which cover 10552h and contain storm time periods 9552h and quiet time periods 1000h. The data are then categorized into three data sets: a training set (6634h), across-validation set (1962h), and a test set (1956h). The validation set is used to determine where the training should be stopped whereas the test set is used for neural networks to get the generalization capability (the out-of-sample performance). Based on the correlation analysis between the Dst index and various solar wind parameters (including various combinations of solar wind parameters), the best coupling functions can be found from the out-of-sample performance of trained neural networks. The coupling functions found are then used to forecast geomagnetic storms one to several hours in advance. The comparisons are made on iterating the single-step prediction several times and on making a non iterated, direct prediction. Thus, we will present the best solar wind-magnetosphere coupling functions and the corresponding prediction results. Interesting Links: Lund Space Weather and AI

  7. Vortex, ULF wave and Aurora Observation after Solar Wind Dynamic Pressure Change

    Science.gov (United States)

    Shi, Q.

    2017-12-01

    Here we will summarize our recent study and show some new results on the Magnetosphere and Ionosphere Response to Dynamic Pressure Change/disturbances in the Solar Wind and foreshock regions. We study the step function type solar wind dynamic pressure change (increase/decrease) interaction with the magnetosphere using THEMIS satellites at both dayside and nightside in different geocentric distances. Vortices generated by the dynamic pressure change passing along the magnetopause are found and compared with model predictions. ULF waves and vortices are excited in the dayside and nightside plasma sheet when dynamic pressure change hit the magnetotail. The related ionospheric responses, such as aurora and TCVs, are also investigated. We compare Global MHD simulations with the observations. We will also show some new results that dayside magnetospheric FLRs might be caused by foreshock structures.Shi, Q. Q. et al. (2013), THEMIS observations of ULF wave excitation in the nightside plasma sheet during sudden impulse events, J. Geophys. Res. Space Physics, 118, doi:10.1029/2012JA017984. Shi, Q. Q. et al. (2014), Solar wind pressure pulse-driven magnetospheric vortices and their global consequences, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019551. Tian, A.M. et al.(2016), Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations, J. Geophys. Res., 121, doi:10.1002/2016JA022459. Shen, X.C. et al.(2015), Magnetospheric ULF waves with increasing amplitude related to solar wind dynamic pressure changes: THEMIS observations, J. Geophys. Res., 120, doi:10.1002/2014JA020913Zhao, H. Y. et al. (2016), Magnetospheric vortices and their global effect after a solar wind dynamic pressure decrease, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA021646. Shen, X. C., et al. (2017), Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse, J. Geophys. Res

  8. Modeling energy production of solar thermal systems and wind turbines for installation at corn ethanol plants

    Science.gov (United States)

    Ehrke, Elizabeth

    Nearly every aspect of human existence relies on energy in some way. Most of this energy is currently derived from fossil fuel resources. Increasing energy demands coupled with environmental and national security concerns have facilitated the move towards renewable energy sources. Biofuels like corn ethanol are one of the ways the U.S. has significantly reduced petroleum consumption. However, the large energy requirement of corn ethanol limits the net benefit of the fuel. Using renewable energy sources to produce ethanol can greatly improve its economic and environmental benefits. The main purpose of this study was to model the useful energy received from a solar thermal array and a wind turbine at various locations to determine the feasibility of applying these technologies at ethanol plants around the country. The model calculates thermal energy received from a solar collector array and electricity generated by a wind turbine utilizing various input data to characterize the equipment. Project cost and energy rate inputs are used to evaluate the profitability of the solar array or wind turbine. The current state of the wind and solar markets were examined to give an accurate representation of the economics of each industry. Eighteen ethanol plant locations were evaluated for the viability of a solar thermal array and/or wind turbine. All ethanol plant locations have long payback periods for solar thermal arrays, but high natural gas prices significantly reduce this timeframe. Government incentives will be necessary for the economic feasibility of solar thermal arrays. Wind turbines can be very profitable for ethanol plants in the Midwest due to large wind resources. The profitability of wind power is sensitive to regional energy prices. However, government incentives for wind power do not significantly change the economic feasibility of a wind turbine. This model can be used by current or future ethanol facilities to investigate or begin the planning process for a

  9. Power Flow Simulations of a More Renewable California Grid Utilizing Wind and Solar Insolation Forecasting

    Science.gov (United States)

    Hart, E. K.; Jacobson, M. Z.; Dvorak, M. J.

    2008-12-01

    Time series power flow analyses of the California electricity grid are performed with extensive addition of intermittent renewable power. The study focuses on the effects of replacing non-renewable and imported (out-of-state) electricity with wind and solar power on the reliability of the transmission grid. Simulations are performed for specific days chosen throughout the year to capture seasonal fluctuations in load, wind, and insolation. Wind farm expansions and new wind farms are proposed based on regional wind resources and time-dependent wind power output is calculated using a meteorological model and the power curves of specific wind turbines. Solar power is incorporated both as centralized and distributed generation. Concentrating solar thermal plants are modeled using local insolation data and the efficiencies of pre-existing plants. Distributed generation from rooftop PV systems is included using regional insolation data, efficiencies of common PV systems, and census data. The additional power output of these technologies offsets power from large natural gas plants and is balanced for the purposes of load matching largely with hydroelectric power and by curtailment when necessary. A quantitative analysis of the effects of this significant shift in the electricity portfolio of the state of California on power availability and transmission line congestion, using a transmission load-flow model, is presented. A sensitivity analysis is also performed to determine the effects of forecasting errors in wind and insolation on load-matching and transmission line congestion.

  10. Long-period variations of wind parameters in the mesopause region and the solar cycle dependence

    International Nuclear Information System (INIS)

    Greisiger, K.M.; Schminder, R.; Kuerschner, D.

    1987-01-01

    The solar cycle dependence of wind parameters below 100 km on the basis of long term continuous ionospheric drift measurements in the low frequency range is discussed. For the meridional prevailing wind no significant variation was found. The same comparison as for winter was done for summer where the previous investigations gave no correlation. Now the radar meteor wind measurement values, too, showed a significant negative correla