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  • 1.
    Andrews, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gurnett, D. A.
    Morgan, D.
    Nemec, F.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Control of the topside Martian ionosphere by crustal magnetic fields2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 4, p. 3042-3058Article in journal (Refereed)
    Abstract [en]

    We present observations from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument onboard Mars Express of the thermal electron plasma density of the Martian ionosphere and investigate the extent to which it is influenced by the presence of Mars's remnant crustal magnetic fields. We use locally measured electron densities, derived when MARSIS is operating in active ionospheric sounding (AIS) mode, covering an altitude range from approximate to 300km to approximate to 1200km. We compare these measured densities to an empirical model of the dayside ionospheric plasma density in this diffusive transport-dominated regime. We show that small spatial-scale departures from the averaged values are strongly correlated with the pattern of the crustal fields. Persistently elevated densities are seen in regions of relatively stronger crustal fields across the whole altitude range. Comparing these results with measurements of the (scalar) magnetic field also obtained by MARSIS/AIS, we characterize the dayside strength of the draped magnetic fields in the same regions. Finally, we provide a revised empirical model of the plasma density in the Martian ionosphere, including parameterizations for both the crustal field-dominated and draping-dominated regimes.

  • 2.
    Andrews, David J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Dieval, C.
    Duru, F.
    Gurnett, D. A.
    Morgan, D.
    Witasse, O.
    Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere2014In: Journal of Geophysical Research-Space Physics, ISSN 2169-9380, Vol. 119, no 5, p. 3944-3960Article in journal (Refereed)
    Abstract [en]

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the European Space Agency's Mars Express (MEX) spacecraft routinely detects evidence of localized plasma density structures in the Martian dayside ionosphere. Such structures, likely taking the form of spatially extended elevations in the plasma density at a given altitude, give rise to oblique reflections in the Active Ionospheric Sounder data. These structures are likely related to the highly varied Martian crustal magnetic field. In this study we use the polar orbit of MEX to investigate the repeatability of the ionospheric structures producing these anomalous reflections, examining data taken in sequences of multiple orbits which pass over the same regions of the Martian surface under similar solar illuminations, within intervals lasting tens of days. Presenting three such examples, or case studies, we show for the first time that these oblique reflections are often incredibly stable, indicating that the underlying ionospheric structures are reliably reformed in the same locations and with qualitatively similar parameters. The visibility, or lack thereof, of a given oblique reflection on a single orbit can generally be attributed to variations in the crustal field within the ionosphere along the spacecraft trajectory. We show that, within these examples, oblique reflections are generally detected whenever the spacecraft passes over regions of intense near-radial crustal magnetic fields (i.e., with a cusp-like configuration). The apparent stability of these structures is an important feature that must be accounted for in models of their origin.

  • 3.
    Andrews, David J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Barabash, S.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gurnett, D. A.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Hall, B. E. S.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Holmström, M.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Lester, M.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Morgan, D. D.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ramstad, R.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Sanchez-Cano, B.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Way, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. NASA Goddard Inst Space Studies, New York, NY USA..
    Witasse, O.
    ESA ESTEC, Noordwijjk, Netherlands..
    Plasma observations during the Mars atmospheric "plume" event of March-April 20122016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 4, p. 3139-3154Article in journal (Refereed)
    Abstract [en]

    We present initial analyses and conclusions from plasma observations made during the reported "Mars plume event" of March-April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator, the cause of which remains to be explained. The estimated brightness of the plume exceeds that expected for auroral emissions, and its projected altitude greatly exceeds that at which clouds are expected to form. We report on in situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the same surface region but at the opposing terminator. Measurements in the ionosphere at the corresponding location frequently show a disturbed structure, though this is not atypical for such regions with intense crustal magnetic fields. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part to the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that the only similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.

  • 4.
    Andrews, David J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fraenz, M.
    Dubinin, E.
    Duru, F.
    Morgan, D.
    Witasse, O.
    Determination of local plasma densities with the MARSIS radar: Asymmetries in the high-altitude Martian ionosphere2013In: Journal of Geophysical Research: Space Physics, ISSN 2169-9380, Vol. 118, no 10, p. 6228-6242Article in journal (Refereed)
    Abstract [en]

    We present a novel method for the automatic retrieval of local plasma density measurements from the Mars advanced radar for subsurface and ionospheric sounding (MARSIS) active ionospheric sounder (AIS) instrument. The resulting large data set is then used to study the configuration of the Martian ionosphere at altitudes above approximate to 300km. An empirical calibration routine is used, which relates the local plasma density to the measured intensity of multiple harmonics of the local plasma frequency oscillation, excited in the plasma surrounding the antenna in response to the transmission of ionospheric sounding pulses. Enhanced accuracy is achieved in higherdensity (n(e)>150cm(-3)) plasmas, when MARSIS AIS is able to directly measure the fundamental frequency of the local plasma oscillation. To demonstrate the usefulness of this data set, the derived plasma densities are binned by altitude and solar zenith angle in regions over weak (|B-c|<20nT) and strong (|B-c|>20nT) crustal magnetic fields, and we find clear and consistent evidence for a significant asymmetry between these two regions. We show that within the approximate to 300-1200km altitude range sampled, the median plasma density is substantially higher on the dayside in regions of relatively stronger crustal fields than under equivalent illuminations in regions of relatively weaker crustal fields. Conversely, on the nightside, median plasma densities are found to be higher in regions of relatively weaker crustal fields. We suggest that the observed asymmetry arises as a result of the modulation of the efficiency of plasma transport processes by the irregular crustal fields and the generally horizontal draped interplanetary magnetic field.

  • 5.
    Andrews, David J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Leyser, Thomas B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Morgan, D. D.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA USA.
    Gurnett, D. A.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA USA.
    Kopf, A. J.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA USA.
    Fallows, K.
    Boston Univ, Ctr Space Phys, Boston, MA USA.
    Withers, P.
    Boston Univ, Ctr Space Phys, Boston, MA USA; Boston Univ, Dept Astron, Commonwealth Ave, Boston, MA USA.
    MARSIS Observations of Field-Aligned Irregularities and Ducted Radio Propagation in the Martian Ionosphere2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 8, p. 6251-6263Article in journal (Refereed)
    Abstract [en]

    Knowledge of Mars's ionosphere has been significantly advanced in recent years by observations from Mars Express and lately Mars Atmosphere and Volatile EvolutioN. A topic of particular interest are the interactions between the planet's ionospheric plasma and its highly structured crustal magnetic fields and how these lead to the redistribution of plasma and affect the propagation of radio waves in the system. In this paper, we elucidate a possible relationship between two anomalous radar signatures previously reported in observations from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on Mars Express. Relatively uncommon observations of localized, extreme increases in the ionospheric peak density in regions of radial (cusp-like) magnetic fields and spread echo radar signatures are shown to be coincident with ducting of the same radar pulses at higher altitudes on the same field lines. We suggest that these two observations are both caused by a high electric field (perpendicular to B) having distinctly different effects in two altitude regimes. At lower altitudes, where ions are demagnetized and electrons magnetized, and recombination dominantes, a high electric field causes irregularities, plasma turbulence, electron heating, slower recombination, and ultimately enhanced plasma densities. However, at higher altitudes, where both ions and electrons are magnetized and atomic oxygen ions cannot recombine directly, the high electric field instead causes frictional heating, a faster production of molecular ions by charge exchange, and so a density decrease. The latter enables ducting of radar pulses on closed field lines, in an analogous fashion to interhemispheric ducting in the Earth's ionosphere.

  • 6.
    Buchert, Stephan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Zangerl, Franz
    Sust, Manfred
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    SWARM observations of equatorial electron densities and topside GPS track losses2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 7, p. 2088-2092Article in journal (Refereed)
    Abstract [en]

    The SWARM satellites have both upward looking GPS receivers and Langmuir probes. The receivers repeatedly lost track of the L1 band signal in January-February 2014 at postsunset hours, when SWARM was at nearly 500km altitude. This indicates that the signal was disturbed by ionospheric irregularities at this height and above. The track losses occurred right at density gradients associated with equatorial plasma bubbles and predominantly where the measured background density was highest. The signal showed strong phase scintillations rather than in amplitude, indicating that SWARM might be in the near field of an ionospheric phase screen. Density biteouts, depletions between steep gradients, were up to almost 3 orders of magnitude deep in the background of a more shallow trough centered at the magnetic equator. Comparison between satellites shows that the biteout structure strongly varied in longitude over approximate to 100km and has in north-south steep walls.

  • 7.
    Edberg, Niklas J. T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bertucci, C.
    IAFE, Buenos Aires, DF, Argentina..
    Gurnett, D. A.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Holmberg, Mika K. G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Jackman, C. M.
    Univ Southampton, Southampton, Hants, England..
    Kurth, W. S.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Menietti, J. D.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Shebanits, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vigren, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Effects of Saturn's magnetospheric dynamics on Titan's ionosphere2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 10, p. 8884-8898Article in journal (Refereed)
    Abstract [en]

    We use the Cassini Radio and Plasma Wave Science/Langmuir probe measurements of the electron density from the first 110 flybys of Titan to study how Saturn's magnetosphere influences Titan's ionosphere. The data is first corrected for biased sampling due to varying solar zenith angle and solar energy flux (solar cycle effects). We then present results showing that the electron density in Titan's ionosphere, in the altitude range 1600-2400km, is increased by about a factor of 2.5 when Titan is located on the nightside of Saturn (Saturn local time (SLT) 21-03h) compared to when on the dayside (SLT 09-15 h). For lower altitudes (1100-1600km) the main dividing factor for the ionospheric density is the ambient magnetospheric conditions. When Titan is located in the magnetospheric current sheet, the electron density in Titan's ionosphere is about a factor of 1.4 higher compared to when Titan is located in the magnetospheric lobes. The factor of 1.4 increase in between sheet and lobe flybys is interpreted as an effect of increased particle impact ionization from approximate to 200eV sheet electrons. The factor of 2.5 increase in electron density between flybys on Saturn's nightside and dayside is suggested to be an effect of the pressure balance between thermal plus magnetic pressure in Titan's ionosphere against the dynamic pressure and energetic particle pressure in Saturn's magnetosphere.

  • 8.
    Edberg, Niklas J. T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Shebanits, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Ågren, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cravens, T. E.
    Girazian, Z.
    Solar cycle modulation of Titan's ionosphere2013In: Journal of Geophysical Research-Space Physics, ISSN 2169-9380, Vol. 118, no 8, p. 5255-5264Article in journal (Refereed)
    Abstract [en]

    During the six Cassini Titan flybys T83-T88 (May 2012 to November 2012) the electron density in the ionospheric peak region, as measured by the radio and plasma wave science instrument/Langmuir probe, has increased significantly, by 15-30%, compared to previous average. These measurements suggest that a longterm change has occurred in the ionosphere of Titan, likely caused by the rise to the new solar maximum with increased EUV fluxes. We compare measurements from TA, TB, and T5, from the declining phase of solar cycle 23 to the recent T83-T88 measurements during cycle 24, since the solar irradiances from those two intervals are comparable. The peak electron densities normalized to a common solar zenith angle N-norm from those two groups of flybys are comparable but increased compared to the solar minimum flybys (T16-T71). The integrated solar irradiance over the wavelengths 1-80nm, i.e., the solar energy flux, F-e, correlates well with the observed ionospheric peak density values. Chapman layer theory predicts that Nnorm<mml:msubsup>Fek</mml:msubsup>, with k=0.5. We find observationally that the exponent k=0.540.18. Hence, the observations are in good agreement with theory despite the fact that many assumptions in Chapman theory are violated. This is also in good agreement with a similar study by Girazian and Withers (2013) on the ionosphere of Mars. We use this power law to estimate the peak electron density at the subsolar point of Titan during solar maximum conditions and find it to be about 6500cm(-3), i.e., 85-160% more than has been measured during the entire Cassini mission.

  • 9.
    Edberg, Niklas J. T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Shebanits, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ågren, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Roussos, E.
    Garnier, P.
    Cravens, T. E.
    Badman, S. V.
    Modolo, R.
    Bertucci, C.
    Dougherty, M. K.
    Extreme densities in Titan's ionosphere during the T85 magnetosheath encounter2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 12, p. 2879-2883Article in journal (Refereed)
    Abstract [en]

    We present Cassini Langmuir probe measurements of the highest electron number densities ever reported from the ionosphere of Titan. The measured density reached 4310cm(-3) during the T85 Titan flyby. This is at least 500cm(-3) higher than ever observed before and at least 50% above the average density for similar solar zenith angles. The peak of the ionospheric density is not reached on this flyby, making the maximum measured density a lower limit. During this flyby, we also report that an impacting coronal mass ejection (CME) leaves Titan in the magnetosheath of Saturn, where it is exposed to shocked solar wind plasma for at least 2 h 45 min. We suggest that the solar wind plasma in the magnetosheath during the CME conditions significantly modifies Titan's ionosphere by an addition of particle impact ionization by precipitating protons.

  • 10.
    Facsko, G.
    et al.
    Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Geodet & Geophys Inst, Sopron, Hungary.;Finnish Meteorol Inst, FIN-00101 Helsinki, Finland..
    Honkonen, I.
    Finnish Meteorol Inst, FIN-00101 Helsinki, Finland.;NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Zivkovic, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. DNV GL, Res & Innovat, Hovik, Norway..
    Palin, Laurianne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Kallio, E.
    Aalto Univ, Sch Elect Engn, Espoo, Finland..
    Ågren, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tanskanen, E. I.
    Aalto Univ, ReSoLVE Ctr Excellence, ELEC Dept Radio Sci & Engn, Espoo, Finland..
    Milan, S.
    Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England..
    One year in the Earth's magnetosphere: A global MHD simulation and spacecraft measurements2016In: Space Weather: The international journal of research and applications, ISSN 1542-7390, E-ISSN 1542-7390, Vol. 14, no 5, p. 351-367Article in journal (Refereed)
    Abstract [en]

    The response of the Earth's magnetosphere to changing solar wind conditions is studied with a 3-D Magnetohydrodynamic (MHD) model. One full year (155 Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic code. Real solar wind measurements are given to the code as input to create the longest lasting global magnetohydrodynamics simulation to date. The applicability of the results of the simulation depends critically on the input parameters used in the model. Therefore, the validity and the variance of the OMNIWeb data are first investigated thoroughly using Cluster measurement close to the bow shock. The OMNIWeb and the Cluster data were found to correlate very well before the bow shock. The solar wind magnetic field and plasma parameters are not changed significantly from the L-1 Lagrange point to the foreshock; therefore, the OMNIWeb data are appropriate input to the GUMICS-4. The Cluster SC3 footprints are determined by magnetic field mapping from the simulation results and the Tsyganenko (T96) model in order to compare two methods. The determined footprints are in rather good agreement with the T96. However, it was found that the footprints agree better in the Northern Hemisphere than the Southern one during quiet conditions. If the B-y is not zero, the agreement of the GUMICS-4 and T96 footprint is worse in longitude in the Southern Hemisphere. Overall, the study implies that a 3-D MHD model can increase our insight of the response of the magnetosphere to solar wind conditions.

  • 11.
    Hall, B. E. S.
    et al.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Lester, M.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Nichols, J. D.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Sanchez-Cano, B.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Uppsala, Sweden..
    Fraenz, M.
    Max Planck Inst Solar Syst Res, Gottingen, Germany..
    A survey of superthermal electron flux depressions, or "electron holes," within the illuminated Martian induced magnetosphere2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 5, p. 4835-4857Article in journal (Refereed)
    Abstract [en]

    Since Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, referred to as electron holes, occur within the Martian induced magnetosphere (IM). We present a statistical analysis of this phenomenon identified from proxy measurements of the electron flux derived from measurements by the Analyser of Space Plasmas and Energetic Neutral Atoms Electron Spectrometer experiment on board the Mars Express (MEX) spacecraft. The study is completed for the period of 9 February 2004 to 9 May 2014. Electron holes are observed within the IM in more than 56% of MEX orbits during this study period, occurring predominantly at altitudes less than 1300km, with the majority in the negative X Mars-Centric Solar Orbital direction. The spatial distribution above the surface of Mars is observed to bear close resemblance to that of the crustal magnetic fields as predicted by the Cain et al. [] magnetic field model, suggesting that they play an important role in the formation of these phenomena.

  • 12.
    Hall, B. E. S.
    et al.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Lester, M.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Sanchez-Cano, B.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Nichols, J. D.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fränz, M.
    Max Planck Inst Solar Syst Res, Gottingen, Germany..
    Holmström, M.
    Swedish Inst Space Phys, Kiruna Div, Kiruna, Sweden..
    Ramstad, R.
    Swedish Inst Space Phys, Kiruna Div, Kiruna, Sweden..
    Witasse, O.
    Ist Nazl Astrofis, Ist Astrofis & Planetol Spaziali, Rome, Italy..
    Cartacci, M.
    European Space Agcy, Estec, Sci Support Off, Noordwijk, Netherlands..
    Cicchetti, A.
    European Space Agcy, Estec, Sci Support Off, Noordwijk, Netherlands..
    Noschese, R.
    European Space Agcy, Estec, Sci Support Off, Noordwijk, Netherlands..
    Orosei, R.
    Ist Nazl Astrofis, Ist Radioastron, Bologna, Italy..
    Annual variations in the Martian bow shock location as observed by the Mars Express mission2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 11, p. 11474-11494Article in journal (Refereed)
    Abstract [en]

    The Martian bow shock distance has previously been shown to be anticorrelated with solar wind dynamic pressure but correlated with solar extreme ultraviolet (EUV) irradiance. Since both of these solar parameters reduce with the square of the distance from the Sun, and Mars' orbit about the Sun increases by similar to 0.3 AU from perihelion to aphelion, it is not clear how the bow shock location will respond to variations in these solar parameters, if at all, throughout its orbit. In order to characterize such a response, we use more than 5 Martian years of Mars Express Analyser of Space Plasma and EneRgetic Atoms (ASPERA-3) Electron Spectrometer measurements to automatically identify 11,861 bow shock crossings. We have discovered that the bow shock distance as a function of solar longitude has a minimum of 2.39 R-M around aphelion and proceeds to a maximum of 2.65 R-M around perihelion, presenting an overall variation of similar to 11% throughout the Martian orbit. We have verified previous findings that the bow shock in southern hemisphere is on average located farther away from Mars than in the northern hemisphere. However, this hemispherical asymmetry is small (total distance variation of similar to 2.4%), and the same annual variations occur irrespective of the hemisphere. We have identified that the bow shock location is more sensitive to variations in the solar EUV irradiance than to solar wind dynamic pressure variations. We have proposed possible interaction mechanisms between the solar EUV flux and Martian plasma environment that could explain this annual variation in bow shock location.

  • 13.
    Kauristie, K.
    et al.
    Finnish Meteorol Inst, Helsinki, Finland..
    Morschhauser, A.
    GFZ German Res Ctr Geosci, Potsdam, Germany..
    Olsen, N.
    Tech Univ Denmark, Natl Space Inst, DTU Space, Lyngby, Denmark..
    Finlay, C. C.
    Tech Univ Denmark, Natl Space Inst, DTU Space, Lyngby, Denmark..
    McPherron, R. L.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Gjerloev, J. W.
    Johns Hopkins Univ, Laurel, MD USA..
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    On the Usage of Geomagnetic Indices for Data Selection in Internal Field Modelling2017In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 206, no 1-4, p. 61-90Article, review/survey (Refereed)
    Abstract [en]

    We present a review on geomagnetic indices describing global geomagnetic storm activity (Kp, am, Dst and dDst/dt) and on indices designed to characterize high latitude currents and substorms (PC and AE-indices and their variants). The focus in our discussion is in main field modelling, where indices are primarily used in data selection criteria for weak magnetic activity. The publicly available extensive data bases of index values are used to derive joint conditional Probability Distribution Functions (PDFs) for different pairs of indices in order to investigate their mutual consistency in describing quiet conditions. This exercise reveals that Dst and its time derivative yield a similar picture as Kp on quiet conditions as determined with the conditions typically used in internal field modelling. Magnetic quiescence at high latitudes is typically searched with the help of Merging Electric Field (MEF) as derived from solar wind observations. We use in our PDF analysis the PC-index as a proxy for MEF and estimate the magnetic activity level at auroral latitudes with the AL-index. With these boundary conditions we conclude that the quiet time conditions that are typically used in main field modelling (, and ) correspond to weak auroral electrojet activity quite well: Standard size substorms are unlikely to happen, but other types of activations (e.g. pseudo breakups ) can take place, when these criteria prevail. Although AE-indices have been designed to probe electrojet activity only in average conditions and thus their performance is not optimal during weak activity, we note that careful data selection with advanced AE-variants may appear to be the most practical way to lower the elevated RMS-values which still exist in the residuals between modeled and observed values at high latitudes. Recent initiatives to upgrade the AE-indices, either with a better coverage of observing stations and improved baseline corrections (the SuperMAG concept) or with higher accuracy in pinpointing substorm activity (the Midlatitude Positive Bay-index) will most likely be helpful in these efforts.

  • 14.
    Liemohn, Michael W.
    et al.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA.
    McCollough, James P.
    US Air Force, Space Vehicles Directorate, Res Lab, Kirtland AFB, NM USA.
    Jordanova, Vania K.
    Los Alamos Natl Lab, Space Sci & Applicat, Los Alamos, NM USA.
    Ngwira, Chigomezyo M.
    Catholic Univ Amer, Dept Phys, Washington, DC USA; NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Morley, Steven K.
    Los Alamos Natl Lab, Space Sci & Applicat, Los Alamos, NM USA.
    Cid, Consuelo
    Univ Alcala De Henares, Dept Phys & Math, Madrid, Spain.
    Tobiska, W. Kent
    Space Environm Technol, Pacific Palisades, CA USA.
    Wintoft, Peter
    Swedish Inst Space Phys, Lund, Sweden.
    Ganushkina, Natalia Yu
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA; Finnish Meteorol Inst, Helsinki, Finland.
    Welling, Daniel T.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA; Univ Texas Arlington, Arlington, TX USA.
    Bingham, Suzy
    UK Met Off, Exeter, Devon, England.
    Balikhin, Michael A.
    Univ Sheffield, Dept Automat Control & Syst Engn, Sheffield, S Yorkshire, England.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Engel, Miles A.
    Los Alamos Natl Lab, Space Sci & Applicat, Los Alamos, NM USA.
    Weigel, Robert S.
    George Mason Univ, Dept Phys & Astron, Fairfax, VA USA.
    Singer, Howard J.
    NOAA, Space Weather Predict Ctr, Boulder, CO USA.
    Buresova, Dalia
    CAS, Inst Atmospher Phys, Prague, Czech Republic.
    Bruinsma, Sean
    Dept Space Geodesy CNES, Toulouse, France.
    Zhelayskaya, Irina S.
    GFZ German Res Ctr Geosci, Potsdam, Germany; Univ Potsdam, Inst Phys & Astron, Potsdam, Germany.
    Shprits, Yuri Y.
    GFZ German Res Ctr Geosci, Potsdam, Germany; Univ Potsdam, Inst Phys & Astron, Potsdam, Germany; UCLA, Dept Earth & Space Sci, Los Angeles, CA USA.
    Vasile, Ruggero
    GFZ German Res Ctr Geosci, Potsdam, Germany.
    Model Evaluation Guidelines for Geomagnetic Index Predictions2018In: Space Weather: The international journal of research and applications, ISSN 1542-7390, E-ISSN 1542-7390, Vol. 16, no 12, p. 2079-2102Article in journal (Refereed)
    Abstract [en]

    Geomagnetic indices are convenient quantities that distill the complicated physics of some region or aspect of near‐Earth space into a single parameter. Most of the best‐known indices are calculated from ground‐based magnetometer data sets, such as Dst, SYM‐H, Kp, AE, AL, and PC. Many models have been created that predict the values of these indices, often using solar wind measurements upstream from Earth as the input variables to the calculation. This document reviews the current state of models that predict geomagnetic indices and the methods used to assess their ability to reproduce the target index time series. These existing methods are synthesized into a baseline collection of metrics for benchmarking a new or updated geomagnetic index prediction model. These methods fall into two categories: (1) fit performance metrics such as root‐mean‐square error and mean absolute error that are applied to a time series comparison of model output and observations and (2) event detection performance metrics such as Heidke Skill Score and probability of detection that are derived from a contingency table that compares model and observation values exceeding (or not) a threshold value. A few examples of codes being used with this set of metrics are presented, and other aspects of metrics assessment best practices, limitations, and uncertainties are discussed, including several caveats to consider when using geomagnetic indices.

  • 15. Lockwood, M
    et al.
    Fazakerley, A
    Opgenoorth, Herman
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Moen, J
    van Eyken, A P
    Dunlop, M
    Bosqued, J M
    Lu, G
    Cully, C
    Eglitis, P
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    McCrea, I W
    Hapgood, M A
    Wild, M N
    Stamper, R
    Denig, W
    Taylor, M
    Wild, J A
    Provan, G
    Amm, O
    Kauristie, K
    Pulkkinen, T
    Stromme, A
    Prikryl, P
    Pitout, F
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Balogh, A
    Reme, H
    Behlke, R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hansen, T
    Greenwald, R
    Frey, H
    Morley, S K
    Alcayde, D
    Blelly, P L
    Donovan, E
    Engebretson, M
    Lester, M
    Watermann, J
    Marcucci, M F
    Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures2001In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 19, no 10-12, p. 1613-1640Article, review/survey (Refereed)
    Abstract [en]

    We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ([X(GSM), Y(GSM), Z(GSM)] approximate to [2, 7, 9] R(E)). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a propagation delay of 75 min that is well-defined by two separate studies: (1) the magnetospheric variations prior to the northward turning (Lockwood et al., 2001, this issue) and (2) the field clock angle seen by Cluster after it had emerged into the magnetosheath (Opgenoorth et al., 2001, this issue). With an additional lag of 16.5 min, the transient LLBL events cor-relate well with swings of the IMF clock angle (in GSM) to near 90degrees. Most of this additional lag is explained by ground-based observations, which reveal signatures of transient reconnection in the pre-noon sector that then take 10-15 min to propagate eastward to 15 MLT, where they are observed by Cluster. The eastward phase speed of these signatures agrees very well with the motion deduced by the cross-correlation of the signatures seen on the four Cluster spacecraft. The evidence that these events are reconnection pulses includes: transient erosion of the noon 630 nm (cusp/cleft) aurora to lower latitudes; transient and travelling enhancements of the flow into the polar cap, imaged by the AMIE technique; and poleward-moving events moving into the polar cap, seen by the EISCAT Svalbard Radar (ESR). A pass of the DMSP-F15 satellite reveals that the open field lines near noon have been opened for some time: the more recently opened field lines were found closer to dusk where the flow transient and the poleward-moving event intersected the satellite pass. The events at Cluster have ion and electron characteristics predicted and observed by Lockwood and Hapgood (1998) for a Flux Transfer Event (FTE), with allowance for magnetospheric ion reflection at Alfvenic disturbances in the magnetopause reconnection layer. Like FTEs, the events are about 1 R(E) in their direction of motion and show a rise in the magnetic field strength, but unlike FTEs, in general, they show no pressure excess in their core and hence, no characteristic bipolar signature in the boundary-normal component. However, most of the events were observed when the magnetic field was southward, i.e. on the edge of the interior magnetic cusp, or when the field was parallel to the magnetic equatorial plane. Only when the satellite begins to emerge from the exterior boundary (when the field was northward), do the events start to show a pressure excess in their core and the consequent bipolar signature. We identify the events as the first observations of FTEs at middle altitudes.

  • 16.
    Mann, I. R.
    et al.
    Univ Alberta, Dept Phys, Edmonton, AB, Canada.
    Di Pippo, S.
    United Nations Off Vienna, Off Outer Space Affairs, Vienna, Austria.
    Opgenoorth, Hermann Josef
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Univ Leicester, Dept Phys & Astron, Leicester, Leics, England.
    Kuznetsova, M.
    NASA, Goddard Spaceflight Ctr, Greenbelt, MD USA.
    Kendall, D. J.
    Canadian Space Agcy, St Hubert, PQ, Canada.
    International Collaboration Within the United Nations Committee on the Peaceful Uses of Outer Space: Framework for International Space Weather Services (2018-2030)2018In: Space Weather: The international journal of research and applications, ISSN 1542-7390, E-ISSN 1542-7390, Vol. 16, no 5, p. 428-433Article in journal (Other academic)
    Abstract [en]

    Severe space weather is a global threat that requires a coordinated global response. In this Commentary, we review some previous successful actions supporting international coordination between member states in the United Nations (UN) context and make recommendations for a future approach. Member states of the UN Committee on the Peaceful Uses of Outer Space (COPUOS) recently approved new guidelines related to space weather under actions for the long-term sustainability of outer space activities. This is to be followed by UN Conference on the Exploration and Peaceful Uses of Outer Space (UNISPACE)+50, which will take place in June 2018 on the occasion of the fiftieth anniversary of the first UNISPACE I held in Vienna in 1968. Expanded international coordination has been proposed within COPUOS under the UNISPACE+50 process, where priorities for 2018-2030 are to be defined under Thematic Priority 4: Framework for International Space Weather Services. The COPUOS expert group for space weather has proposed the creation of a new International Coordination Group for Space Weather be implemented as part of this thematic priority. This coordination group would lead international coordination between member states and across international stakeholders, monitor progress against implementation of guidelines and best practices, and promote coordinated global efforts in the space weather ecosystem spanning observations, research, modeling, and validation, with the goal of improved space weather services. We argue that such improved coordination at the international policy level is essential for increasing global resiliency against the threats arising from severe space weather.

  • 17.
    Marque, Christophe
    et al.
    Royal Observ Belgium, Solar Terr Ctr Excellence SIDC, Ave Circulaire 3, B-1180 Brussels, Belgium.
    Klein, Karl-Ludwig
    CNRS, LESIA UMR 8109, F-92190 Meudon, France;CNRS, Stn Radioastron Nancay, Observ Paris, F-92190 Meudon, France;PSL Res Univ, Paris, France;Univ P&M Curie, Paris, France;Univ Paris Diderot, Paris, France;Univ Orleans, Orleans, France;OSUC, Orleans, France.
    Monstein, Christian
    Swiss Fed Inst Technol, Inst Particle Phys & Astrophys, Wolfgang Pauli Str 27, CH-8093 Zurich, Switzerland.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Pulkkinen, Antti
    Goddard Space Flight Ctr Greenbelt, Greenbelt, MD USA.
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Krucker, Saem
    Univ Appl Sci & Arts Northwestern Switzerland, Windisch, Switzerland.
    Van Hoof, Rudiger
    Belgocontrol, Tervuursesteenweg 303, B-1820 Steenokkerzeel, Belgium.
    Thulesen, Peter
    Air Greenland Engn Dept, POB 1012, Nuuk, Greenland.
    Solar radio emission as a disturbance of aeronautical radionavigation2018In: Journal of Space Weather and Space Climate, ISSN 2115-7251, E-ISSN 2115-7251, Vol. 8, article id A42Article in journal (Refereed)
    Abstract [en]

    On November 4th, 2015 secondary air traffic control radar was strongly disturbed in Sweden and some other European countries. The disturbances occurred when the radar antennas were pointing at the Sun. In this paper, we show that the disturbances coincided with the time of peaks of an exceptionally strong (similar to 10(5) Solar Flux Units) solar radio burst in a relatively narrow frequency range around 1 GHz. This indicates that this radio burst is the most probable space weather candidate for explaining the radar disturbances. The dynamic radio spectrum shows that the high flux densities are not due to synchrotron emission of energetic electrons, but to coherent emission processes, which produce a large variety of rapidly varying short bursts (such as pulsations, fiber bursts, and zebra patterns). The radio burst occurs outside the impulsive phase of the associated flare, about 30 min after the soft X-ray peak, and it is temporarily associated with fast evolving activity occurring in strong solar magnetic fields. While the relationship with strong magnetic fields and the coherent spectral nature of the radio burst provide hints towards the physical processes which generate such disturbances, we have so far no means to forecast them. Well-calibrated monitoring instruments of whole Sun radio fluxes covering the UHF band could at least provide a real-time identification of the origin of such disturbances, which reports in the literature show to also affect GPS signal reception.

  • 18. Nikolaev, A. V.
    et al.
    Sergeev, V. A.
    Tsyganenko, N. A.
    Kubyshkina, M. V.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Singer, H.
    Angelopoulos, V.
    A quantitative study of magnetospheric magnetic field line deformation by a two-loop substorm current wedge2015In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, no 4, p. 505-517Article in journal (Refereed)
    Abstract [en]

    Substorm current wedge (SCW) formation is associated with global magnetic field reconfiguration during substorm expansion. We combine a two-loop model SCW (SCW2L) with a background magnetic field model to investigate distortion of the ionospheric footpoint pattern in response to changes of different SCW2L parameters. The SCW-related plasma sheet footprint shift results in formation of a pattern resembling an auroral bulge, the poleward expansion of which is controlled primarily by the total current in the region 1 sense current loop (I-1). The magnitude of the footprint latitudinal shift may reach similar to 10 degrees corrected geomagnetic latitude (CGLat) during strong sub-storms (I-1 = 2 MA). A strong helical magnetic field around the field-aligned current generates a surge-like region with embedded spiral structures, associated with a westward traveling surge (WTS) at the western end of the SCW. The helical field may also contribute to rotation of the ionospheric projection of narrow plasma streams (auroral streamers). Other parameters, including the total current in the second (region 2 sense) loop, were found to be of secondary importance. Analyzing two consecutive dipolarizations on 17 March 2010, we used magnetic variation data obtained from a dense midlatitude ground network and several magnetospheric spacecraft, as well as the adaptive AM03 model, to specify SCW2L parameters, which allowed us to predict the magnitude of poleward auroral expansion. Auroral observations made during the two substorm activations demonstrate that the SCW2L combined with the AM03 model nicely describes the azimuthal progression and the observed magnitude of the auroral expansion. This finding indicates that the SCW-related distortions are responsible for much of the observed global development of bright auroras.

  • 19.
    Opgenoorth, Hermann J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fraenz, M.
    Lester, M.
    Edberg, N. J. T.
    Morgan, D.
    Duru, F.
    Witasse, O.
    Williams, A. O.
    Mars ionospheric response to solar wind variability2013In: Journal of Geophysical Research: Space Physics, ISSN 2169-9380, Vol. 118, no 10, p. 6558-6587Article in journal (Refereed)
    Abstract [en]

    At planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was located behind Earth in the Solar wind; thus, we can use coordinated data from multiple near-Earth spacecraft (Stereo, Wind) to evaluate what kind of Solar wind disturbances have passed by Earth and might consecutively hit Mars, and when. We employ plasma data from the ESA Mars-Express mission, the ASPERA-3 particle instrument, and the MARSIS Active Ionospheric Sounder (AIS) to investigate, for a number of isolated events in March and April 2010, how the ionosphere and the induced magnetosphere at Mars develop and decay in response to Solar wind variability in the magnetic field, density, and velocity. In a dedicated campaign mode, we use frequent long-duration MARSIS AIS operations for several consecutive orbits, to monitor for the first time the long-term development of the Martian plasma environment during solar wind disturbances. We find that the magnetosphere and ionosphere of Mars can become considerably compressed by solar wind dynamic pressure variations, which usually are also associated with changes in the magnetic draping of the interplanetary magnetic field around the planet. These are typically associated with corotating interaction regions and coronal mass ejections, and can last for several days. During such episodes of compression, we see signatures of increased plasma transport over the terminator and enhanced ion outflow from the upper atmosphere.

  • 20.
    Palin, Laurianne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Jacquey, C.
    Univ Toulouse, CNRS, IRAP, Toulouse, France..
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Connors, M.
    Athabasca Univ, Dept Phys, Edmonton, AB, Canada..
    Sergeev, V.
    St Petersburg State Univ, Dept Earths Phys, St Petersburg 199034, Russia..
    Sauvaud, J-A
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Reeves, G. D.
    Los Alamos Natl Lab, Los Alamos, NM USA..
    Singer, H. J.
    NOAA, Space Weather Predict Ctr, Boulder, CO USA..
    Angelopoulos, V.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, IGPP, Los Angeles, CA USA..
    Turc, L.
    European Space Res & Technol Ctr ESA, Directorate Sci & Robot Explorat, Sci Support Off, Noordwijk, Netherlands..
    Three-dimensional current systems and ionospheric effects associated with small dipolarization fronts2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 5, p. 3739-3757Article in journal (Refereed)
    Abstract [en]

    We present a case study of eight successive plasma sheet (PS) activations (usually referred to as bursty bulk flows or dipolarization fronts), associated with small individual B-ZGSM increases on 31 March 2009 (0200-0900 UT), observed by the Time History of Events and Macroscale Interactions During Substorms mission. This series of events happens during very quiet solar wind conditions, over a period of 7 h preceding a substorm onset at 1230 UT. The amplitude of the dipolarizations increases with time. The low-amplitude dipolarization fronts are associated with few (1 or 2) rapid flux transport events (RFT, E-h > 2 mV/m), whereas the large-amplitude ones encompass many more RFT events. All PS activations are associated with small and localized substorm current wedge (SCW)-like current system signatures, which seems to be the consequence of RFT arrival in the near tail. The associated ground magnetic perturbations affect a larger part of the contracted auroral oval when, in the magnetotail, more RFT are embedded in PS activations (> 5). Dipolarization fronts with very low amplitude, a type usually not included in statistical studies, are of particular interest because we found even those to be associated with clear small SCW-like current system and particle injections at geosynchronous orbit. This exceptional data set highlights the role of flow bursts in the magnetotail and leads to the conclusion that we may be observing the smallest form of a substorm or rather its smallest element. This study also highlights the gradual evolution of the ionospheric current disturbance as the plasma sheet is observed to heat up.

  • 21.
    Palin, Laurianne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ågren, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Zivkovic, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sergeev, V. A.
    St Petersburg State Univ, Fac Phys, St Petersburg, Russia..
    Kubyshkina, M. V.
    St Petersburg State Univ, Fac Phys, St Petersburg, Russia..
    Nikolaev, A.
    St Petersburg State Univ, Fac Phys, St Petersburg, Russia..
    Kauristie, K.
    Finnish Meteorol Inst, Earth Observat Unit, Helsinki, Finland..
    van de Kamp, M.
    Finnish Meteorol Inst, Earth Observat Unit, Helsinki, Finland..
    Amm, O.
    Finnish Meteorol Inst, Earth Observat Unit, Helsinki, Finland..
    Milan, S. E.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Imber, S. M.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Facsko, G.
    Finnish Meteorol Inst, Earth Observat Unit, Helsinki, Finland.;Hungarian Acad Sci, Geodet & Geophys Inst, Res Ctr Astron & Earth Sci, Sopron, Hungary..
    Palmroth, M.
    Finnish Meteorol Inst, Earth Observat Unit, Helsinki, Finland..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Modulation of the substorm current wedge by bursty bulk flows: 8 September 2002- Revisited2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 5, p. 4466-4482Article in journal (Refereed)
    Abstract [en]

    The ultimate formation mechanism of the substorm current wedge (SCW) remains to date unclear. In this study, we investigate its relationship to plasma flows at substorm onset and throughout the following expansion phase. We revisit the case of 8 September 2002, which has been defined as one of the best textbook examples of a substorm because of its excellent coverage by both spacecraft in the magnetotail and ground-based observatories. We found that a dense sequence of arrival of nightside flux transfer events (NFTEs; which can be understood as the lobe magnetic signature due to a bursty bulk flow travelling earthward in the central plasma sheet) in the near-Earth tail leads to a modulation (and further step-like builtup) of the SCW intensity during the substorm expansion phase. In addition, we found that small SCWs are created also during the growth phase of the event in association with another less intense sequence of NFTEs. The differences between the sequence of NFTEs in the growth and expansion phase are discussed. We conclude that the envelope of the magnetic disturbances which we typically refer to as an intense magnetic substorm is the result of a group or sequence of more intense and more frequent NFTEs.

  • 22.
    Sanchez-Cano, B.
    et al.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Hall, B. E. S.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Lester, M.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Mays, M. L.
    NASA Goddard Space Flight Ctr, Heliophys Sci Div, Greenbelt, MD USA..
    Witasse, O.
    ESTEC Sci Support Off, European Space Agcy, Noordwijk, Netherlands..
    Ambrosi, R.
    Univ Leicester, Dept Phys & Astron, Space Res Ctr, Leicester, Leics, England..
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cartacci, M.
    Ist Nazl Astrofis, Ist Astrofis & Planetol Spaziali, Rome, Italy..
    Cicchetti, A.
    Ist Nazl Astrofis, Ist Astrofis & Planetol Spaziali, Rome, Italy..
    Holmstrom, M.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Imber, S.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Kajdic, P.
    Univ Nacl Autonoma Mexico, Inst Geofis, Ciudad Univ, Mexico City, DF, Mexico..
    Milan, S. E.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp, Leicester, Leics, England..
    Noschese, R.
    Ist Nazl Astrofis, Ist Astrofis & Planetol Spaziali, Rome, Italy..
    Odstrcil, D.
    George Mason Univ, Sch Phys Astron & Computat Sci, Fairfax, VA 22030 USA..
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Plaut, J.
    Jet Prop Lab, Pasadena, CA USA..
    Ramstad, R.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Reyes-Ayala, K. I.
    Univ Nacl Autonoma Mexico, Inst Geofis, Ciudad Univ, Mexico City, DF, Mexico..
    Mars plasma system response to solar wind disturbances during solar minimum2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 6, p. 6611-6634Article in journal (Refereed)
    Abstract [en]

    This paper is a phenomenological description of the ionospheric plasma and induced magnetospheric boundary (IMB) response to two different types of upstream solar wind events impacting Mars in March 2008, at the solar minimum. A total of 16 Mars Express orbits corresponding to five consecutive days is evaluated. Solar TErrestrial RElations Observatory-B (STEREO-B) at 1AU and Mars Express and Mars Odyssey at 1.644AU detected the arrival of a small transient interplanetary coronal mass ejection (ICME-like) on the 6 and 7 of March, respectively. This is the first time that this kind of small solar structure is reported at Mars's distance. In both cases, it was followed by a large increase in solar wind velocity that lasted for similar to 10days. This scenario is simulated with the Wang-Sheeley-Arge (WSA) - ENLIL + Cone solar solar wind model. At Mars, the ICME-like event caused a strong compression of the magnetosheath and ionosphere, and the recovery lasted for similar to 3 orbits (similar to 20h). After that, the fast stream affected the upper ionosphere and the IMB, which radial and tangential motions in regions close to the subsolar point are analyzed. Moreover, a compression in the Martian plasma system is also observed, although weaker than after the ICME-like impact, and several magnetosheath plasma blobs in the upper ionosphere are detected by Mars Express. We conclude that, during solar minimum and at aphelion, small solar wind structures can create larger perturbations than previously expected in the Martian system.

  • 23. Sanchez-Cano, B.
    et al.
    Morgan, D. D.
    Witasse, O.
    Radicella, S. M.
    Herraiz, M.
    Orosei, R.
    Cartacci, M.
    Cicchetti, A.
    Noschese, R.
    Kofman, W.
    Grima, C.
    Mouginot, J.
    Gurnett, D. A.
    Lester, M.
    Blelly, P. -L
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Quinsac, G.
    Total electron content in the Martian atmosphere: A critical assessment of the Mars Express MARSIS data sets2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 3, p. 2166-2182Article in journal (Refereed)
    Abstract [en]

    The total electron content (TEC) is one of the most useful parameters to evaluate the behavior of the Martian ionosphere because it contains information on the total amount of free electrons, the main component of the Martian ionospheric plasma. The Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar is able to derive TEC from both of its operation modes: (1) the active ionospheric sounding (AIS) mode and (2) the subsurface mode. TEC estimates from the subsurface sounding mode can be computed from the same raw data independently using different algorithms, which should yield similar results. Significant differences on the dayside, however, have been found from two of the algorithms. Moreover, both algorithms seem also to disagree with the TEC results from the AIS mode. This paper gives a critical, quantitative, and independent assessment of these discrepancies and indicates the possible uncertainty of these databases. In addition, a comparison between the results given by the empirical model of the Martian ionosphere developed by Sanchez-Cano et al. (2013) and the different data sets has been performed. The main result is that for solar zenith angles higher than 75 degrees, where the maximum plasma frequency is typically small compared with the radar frequencies, the two subsurface algorithms can be confidently used. For solar zenith angles less than 75 degrees, where the maximum plasma frequency is very close to the radar frequencies, both algorithms suffer limitations. Nevertheless, despite the solar zenith angle restrictions, the dayside TEC of one of the two algorithms is consistent with the modeled TEC.

  • 24. Schrijver, Carolus J.
    et al.
    Kauristie, Kirsti
    Aylward, Alan D.
    Denardini, Clezio M.
    Gibson, Sarah E.
    Glover, Alexi
    Gopalswamy, Nat
    Grande, Manuel
    Hapgood, Mike
    Heynderickx, Daniel
    Jakowski, Norbert
    Kalegaev, Vladimir V.
    Lapenta, Giovanni
    Linker, Jon A.
    Liu, Siqing
    Mandrini, Cristina H.
    Mann, Ian R.
    Nagatsuma, Tsutomu
    Nandy, Dibyendu
    Obara, Takahiro
    O'Brien, T. Paul
    Onsager, Terrance
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Terkildsen, Michael
    Valladares, Cesar E.
    Vilmer, Nicole
    Understanding space weather to shield society: A global road map for 2015-2025 commissioned by COSPAR and ILWS2015In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 55, no 12, p. 2745-2807Article in journal (Refereed)
    Abstract [en]

    There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that comes the need to better shield society against space weather by improving forecasts, environmental specifications, and infrastructure design. We recognize that much progress has been made and continues to be made with a powerful suite of research observatories on the ground and in space, forming the basis of a Sun Earth system observatory. But the domain of space weather is vast extending from deep within the Sun to far outside the planetary orbits and the physics complex including couplings between various types of physical processes that link scales and domains from the microscopic to large parts of the solar system. Consequently, advanced understanding of space weather requires a coordinated international approach to effectively provide awareness of the processes within the Sun Earth system through observation-driven models. This roadmap prioritizes the scientific focus areas and research infrastructure that are needed to significantly advance our understanding of space weather of all intensities and of its implications for society. Advancement of the existing system observatory through the addition of small to moderate state-of-the-art capabilities designed to fill observational gaps will enable significant advances. Such a strategy requires urgent action: key instrumentation needs to be sustained, and action needs to be taken before core capabilities are lost in the aging ensemble. We recommend advances through priority focus (1) on observation-based modeling throughout the Sun Earth system, (2) on forecasts more than 12 h ahead of the magnetic structure of incoming coronal mass ejections, (3) on understanding the geospace response to variable solar-wind stresses that lead to intense geomagnetically-induced currents and ionospheric and radiation storms, and (4) on developing a comprehensive specification of space climate, including the characterization of extreme space storms to guide resilient and robust engineering of technological infrastructures. The roadmap clusters its implementation recommendations by formulating three action pathways, and outlines needed instrumentation and research programs and infrastructure for each of these. An executive summary provides an overview of all recommendations.

  • 25.
    Stolle, Claudia
    et al.
    Geoforschungszentrum Potsdam, Potsdam, Germany..
    Olsen, Nils
    Tech Univ Denmark, DTU Space, Copenhagen, Denmark.
    Richmond, Arthur D.
    Natl Ctr Atmospher Res, High Altitude Observ, Pob 3000, Boulder, CO 80307 USA..
    Opgenoorth, Hermann J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Topical Volume on Earth's Magnetic Field-Understanding Geomagnetic Sources from the Earth's Interior and Its Environment2017In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 206, no 1-4, p. 1-3Article in journal (Other academic)
  • 26.
    Uspensky, M
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Eglitis, P
    Partamies, N
    Starkov, G
    Fabirovsky, A
    Opgenoorth, H
    Department of Physics and Astronomy.
    Pulkkinen, T
    Pellinen, R
    HF Radar observations of an isolated substorm after prolonged quiet geomagnetic conditions2000In: Fifth International Conference on Substorms, ESA SP-443, 2000, p. 95-98Conference paper (Other scientific)
  • 27.
    Welling, D. T.
    et al.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA; Univ Texas Arlington, Dept Phys, Arlington, TX USA.
    Ngwira, C. M.
    Catholic Univ Amer, Dept Phys, Washington, DC USA; NASA, Goddard Space Flight Ctr, Space Weather Lab, Greenbelt, MD USA.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Univ Leicester, Dept Phys & Astron, Leicester, Leics, England.
    Haiducek, J. D.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA.
    Savani, N. P.
    NASA, Goddard Space Flight Ctr, Space Weather Lab, Greenbelt, MD USA; Univ Maryland Baltimore Cty, Goddard Planetary Heliophys Inst, Baltimore, MD USA.
    Morley, S. K.
    Los Alamos Natl Lab, Space Sci & Applicat, Los Alamos, NM USA.
    Cid, C.
    Univ Alcala De Henares, Space Weather Res Grp, Alcala De Henares, Spain.
    Weigel, R. S.
    George Mason Univ, Dept Phys & Astron, Space Weather Lab, Fairfax, VA USA.
    Weygand, J. M.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA.
    Woodroffe, J. R.
    Los Alamos Natl Lab, Space Sci & Applicat, Los Alamos, NM USA.
    Singer, H. J.
    NOAA, Space Weather Predict Ctr, Boulder, CO USA.
    Rosenqvist, L.
    Swedish Def Res Agcy, Stockholm, Sweden.
    Liemohn, M. W.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI USA.
    Recommendations for Next-Generation Ground Magnetic Perturbation Validation2018In: Space Weather: The international journal of research and applications, ISSN 1542-7390, E-ISSN 1542-7390, Vol. 16, no 12, p. 1912-1920Article in journal (Refereed)
    Abstract [en]

    Data-model validation of ground magnetic perturbation forecasts, specifically of the time rate of change of surface magnetic field, dB/dt, is a critical task for model development and for mitigation of geomagnetically induced current effects. While a current, community-accepted standard for dB/dt validation exists (Pulkkinen et al., 2013), it has several limitations that prevent more complete understanding of model capability. This work presents recommendations from the International Forum for Space Weather Capabilities Assessment Ground Magnetic Perturbation Working Team for creating a next-generation validation suite. Four recommendations are made to address the existing suite: greatly expand the number of ground observatories used, expand the number of events included in the suite from six to eight, generate metrics as a function of magnetic local time, and generate metrics as a function of activity type. For each of these, implementation details are explored. Limitations and future considerations are also discussed.

  • 28.
    Witasse, O.
    et al.
    European Space Agcy, ESTEC.
    Sanchez-Cano, B.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Mays, M. L.
    NASA Goddard Space Flight Ctr, Heliophys Sci Div.
    Kajdic, P.
    Univ Nacl Autonoma Mexico, Inst Geofis.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Elliott, H. A.
    Southwest Res Inst, San Antonio.
    Richardson, I. G.
    NASA Goddard Space Flight Ctr, Heliophys Sci Div.;Univ Maryland, Dept Astron.
    Zouganelis, I.
    European Space Agcy, ESAC, Villanueva De La Canada.
    Zender, J.
    European Space Agcy, ESTEC.
    Wimmer-Schweingruber, R. F.
    Univ Kiel, Inst Expt & Appl Phys.
    Turc, L.
    European Space Agcy, ESTEC.
    Taylor, M. G. G. T.
    European Space Agcy, ESTEC.
    Roussos, E.
    Max Planck Inst Solar Syst Res Justus von Liebig.
    Rouillard, A.
    IRAP, Toulouse.
    Richter, I.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterrestrial Phys.
    Richardson, J. D.
    MIT, Ctr Space Res, Cambridge.
    Ramstad, R.
    Swedish Inst Space Phys, IRF, Kiruna.
    Provan, G.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Posner, A.
    NASA Headquarters, Sci Miss Directorate.
    Plaut, J. J.
    Jet Prop Lab, Pasadena.
    Odstrcil, D.
    George Mason Univ, Dept Phys & Astron.;NASA Goddard Space Flight Ctr, Space Weather Lab.
    Nilsson, H.
    Swedish Inst Space Phys, IRF, Kiruna.
    Niemenen, P.
    European Space Agcy, ESTEC.
    Milan, S. E.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Mandt, K.
    Southwest Res Inst, San Antonio.; UTSA, Dept Phys & Astron, San Antonio.
    Lohf, H.
    Univ Kiel, Inst Expt & Appl Phys.
    Lester, M.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Lebreton, J. -P
    Univ Orleans, CNRS, LPC2E.
    Kuulkers, E.
    European Space Agcy, ESTEC.
    Krupp, N.
    Max Planck Inst Solar Syst Res Justus von Liebig.
    Koenders, C.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterrestrial Phys.
    James, M. K.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Intzekara, D.
    European Space Agcy, ESTEC.; European Space Agcy, ESAC, Villanueva De La Canada.
    Holmstrom, M.
    Swedish Inst Space Phys, IRF, Kiruna.
    Hassler, D. M.
    Southwest Res Inst, Boulder.; Inst Astrophys Spatiale, Orsay.
    Hall, B. E. S.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Guo, J.
    Univ Kiel, Inst Expt & Appl Phys.
    Goldstein, R.
    Southwest Res Inst, San Antonio.
    Goetz, C.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterrestrial Phys.
    Glassmeier, K. H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterrestrial Phys.
    Genot, V.
    IRAP, Toulouse.
    Evans, H.
    European Space Agcy, ESTEC.
    Espley, J.
    Goddard Space Flight Ctr, Lab Planetary Magnetospheres, Greenbelt.
    Edberg, N. J. T.
    Swedish Inst Space Phys, IRF, Uppsala, Sweden..
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cowley, S. W. H.
    Univ Leicester, Dept Phys & Astron, Radio & Space Plasma Phys Grp.
    Burch, J.
    Southwest Res Inst, San Antonio.
    Behar, E.
    Swedish Inst Space Phys, IRF, Kiruna.
    Barabash, S.
    Swedish Inst Space Phys, IRF, Kiruna.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Altobelli, N.
    European Space Agcy, ESAC, Villanueva De La Canada.
    Interplanetary coronal mass ejection observed at STEREO-A, Mars, comet 67P/Churyumov-Gerasimenko, Saturn, and New Horizons en route to Pluto: Comparison of its Forbush decreases at 1.4, 3.1, and 9.9 AU2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 8, p. 7865-7890Article in journal (Refereed)
    Abstract [en]

    We discuss observations of the journey throughout the Solar System of a large interplanetary coronal mass ejection (ICME) that was ejected at the Sun on 14 October 2014. The ICME hit Mars on 17 October, as observed by the Mars Express, Mars Atmosphere and Volatile EvolutioN Mission (MAVEN), Mars Odyssey, and Mars Science Laboratory (MSL) missions, 44h before the encounter of the planet with the Siding-Spring comet, for which the space weather context is provided. It reached comet 67P/Churyumov-Gerasimenko, which was perfectly aligned with the Sun and Mars at 3.1 AU, as observed by Rosetta on 22 October. The ICME was also detected by STEREO-A on 16 October at 1 AU, and by Cassini in the solar wind around Saturn on the 12 November at 9.9AU. Fortuitously, the New Horizons spacecraft was also aligned with the direction of the ICME at 31.6 AU. We investigate whether this ICME has a nonambiguous signature at New Horizons. A potential detection of this ICME by Voyager 2 at 110-111 AU is also discussed. The multispacecraft observations allow the derivation of certain properties of the ICME, such as its large angular extension of at least 116 degrees, its speed as a function of distance, and its magnetic field structure at four locations from 1 to 10 AU. Observations of the speed data allow two different solar wind propagation models to be validated. Finally, we compare the Forbush decreases (transient decreases followed by gradual recoveries in the galactic cosmic ray intensity) due to the passage of this ICME at Mars, comet 67P, and Saturn.

  • 29.
    Zivkovic, Tatjana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ritter, P.
    Palin, Laurianne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Investigation of energy transport and thermospheric upwelling during quiet magnetospheric and ionospheric conditions from the studies of low- and middle-altitude cusp2015In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, no 6, p. 623-635Article in journal (Refereed)
    Abstract [en]

    We investigate energy fluxes and small, kilometre-scale Birkeland currents in the magnetospheric cusp at a 1-3 Earth radii altitude and in the ionosphere using satellites when they were, according to the Tsyganenko model, in magnetic conjunction within 50-60 km and up to 15 min apart. We use Cluster and CHAMP satellites, and study three conjunction events that occurred in 2008 and 2009, when the Cluster spacecraft were crossing the cusps at only a few Earth radii altitude. Our goal is to understand better the influence of processes in the magnetospheric cusp on the upper thermosphere and its upwelling which was usually observed by the CHAMP satellite passing the cusp. Three studied events occurred under relatively quiet and steady magnetospheric and ionospheric conditions, which explains why observed thermospheric density enhancements were rather low. Our findings point out that for each studied event soft electron precipitation influences thermospheric density enhancements in a way that stronger electron precipitation produces stronger thermospheric upwelling. Therefore, in the case of these weak events, soft electron precipitation seems to be more important cause of the observed, thermospheric density enhancements than is the Joule heating.

1 - 29 of 29
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