Solar wind‐driven variations of electron plasma sheet densities and temperatures beyond geostationary orbit during storm times

The empirical models of the plasma sheet electron temperature and density on the nightside at distances between 6 and 11 RE are constructed based on Time History of Events and Macroscale Interactions During Substorms (THEMIS) particle measurements. The data set comprises ∼400 h of observations in the plasma sheet during geomagnetic storm periods. The equatorial distribution of the electron density reveals a strong earthward gradient and a moderate variation with magnetic local time symmetric with respect to the midnight meridian. The electron density dependence on the external driving is parameterized by the solar wind proton density averaged over 4 h and the southward component of interplanetary magnetic field (IMF BS) averaged over 6 h. The interval of the IMF integration is much longer than a typical substorm growth phase, and it rather corresponds to the geomagnetic storm main phase duration. The solar wind proton density is the main controlling parameter, but the IMF BS becomes of almost the same importance in the near‐Earth region. The root‐mean‐square deviation between the observed and predicted plasma sheet density values is 0.23 cm−3, and the correlation coefficient is 0.82. The equatorial distribution of the electron temperature has a maximum in the postmidnight to morning MLT sector, and it is highly asymmetric with respect to the local midnight. The electron temperature model is parameterized by solar wind velocity (averaged over 4 h), IMF BS (averaged over 45 min), and IMF BN (northward component of IMF, averaged over 2 h). The solar wind velocity is a major controlling parameter, and IMF BS and BN are comparable in importance. In contrast to the density model, the electron temperature shows higher correlation with the IMF BS averaged over ∼45 min (substorm growth phase time scale). The effect of BN manifests mostly in the outer part of the modeled region (r > 8RE). The influence of the IMF BS is maximal in the midnight to postmidnight MLT sector. The correlation coefficient between the observed and predicted plasma sheet electron temperature values is 0.76, and the root‐mean‐square deviation is 2.6 keV. Both models reveal better performance in the dawn MLT sector.Key PointsEmpirical models of electron density and temperature at r = 6–11 Re on the nightside are constructedThe model performance has been essentially improved by using lagged and time‐averaged solar wind parameters as a model inputElectron temperature and density correllate best with IMF Bs averaged over substorm growth phase and storm main phase periods, respectivelyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134493/1/jgra52881.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134493/2/jgra52881_am.pd

Ionospheric currents estimated simultaneously from CHAMP satelliteand IMAGE ground-based magnetic field measurements: a statisticalstudy at auroral latitudes

One important contribution to the magnetic field measured at satellite altitude and at ground level comes from the external currents. We used the total field data sampled by the Overhauser Magnetometer on CHAMP and the horizontal magnetic field measurements of the IMAGE ground-based magnetometer network to study the ionospheric Hall current system in the auroral regions. For the CHAMP data a current model consisting of a series of lines and placed at a height of 110km is fitted to the magnetic field signature sampled on the passage across the polar region. The derived current distributions depend, among others, on season and on the local time of the satellite track. At dawn/dusk the auroral electrojets can be detected most clearly in the auroral regions. Their intensity and location are evidently correlated with the <i>A E</i> activity index. For a period of almost two years the results obtained from space and the currents determined from ground-based observations are studied. For the full IMAGE station array a newly-developed method of spherical elementary current systems (SECS) is employed to compute the 2-D equivalent current distribution, which gives a detailed picture of an area covering latitudes 60° – 80° N and 10° – 30° E in the auroral region. Generally, the current estimates from satellite and ground are in good agreement. The results of this survey clearly show the average dependence of the auroral electrojet on season and local time. This is particularly true during periods of increased auroral activity. The correlation coefficient of the results is close to one in the region of sizeable ionospheric current densities. Also the ratio of the current densities, as determined from above and below the ionosphere, is close to unity. It is the first time that the method of Hall current estimate from a satellite has been validated quantitatively by ground-based observations. Among others, this result is of interest for magnetic main field modelling, since it demonstrates that ground-based observations can be used to predict electrojet signatures in satellite magnetic field scalar data.<br><br> <b>Key words.</b> Ionosphere (auroral Ionosphere; electric fields and currents; ionosphere-magnetosphere interactions

[2,6-Bis(2-pyrimidinylthiomethyl)pyridine]dichlorocopper(II) methanol solvate

In the title compound [CuCl2(C15H13N5S2].CH3OH, the Cu2+ ion has square-pyramidal coordination geometry. The basal plane of the pyramid is formed by two Cl- ions, one pyridine N atom and one pyrimidine N atom. The fifth coordination site is occupied by the S atom of a thiomethyl group. The methanol molecule occupies an otherwise empty space in the structure

Inverse proximity effect in superconductors near ferromagnetic material

We study the electronic density of states in a mesoscopic superconductor near a transparent interface with a ferromagnetic metal. In our tunnel spectroscopy experiment, a substantial density of states is observed at sub-gap energies close to a ferromagnet. We compare our data with detailed calculations based on the Usadel equation, where the effect of the ferromagnet is treated as an effective boundary condition. We achieve an excellent agreement with theory when non-ideal quality of the interface is taken into account.Comment: revised, 7 pages, 3 figure

Diethyl 2,2'-[1,3-phenylenebis(methylthio)]dibenzoate

The title molecule, C26H26O4S2, assumes C2 symmetry with two C atoms and two H atoms of the central phenyl ring located on the twofold axis. The S atoms are synplanar with the benzene moiety, so the observed geometry is suitable for CS2 coordination. The o-(ethoxycarbonyl)phenylthiomethyl moiety is approximately planar and its orientation is almost perpendicular with respect to the central phenyl group

Measurement crosstalk between two phase qubits coupled by a coplanar waveguide

We analyze the measurement crosstalk between two flux-biased phase qubits coupled by a resonant coplanar waveguide cavity. After the first qubit is measured, the superconducting phase can undergo damped oscillations resulting in an a.c. voltage that produces a frequency chirped noise signal whose frequency crosses that of the cavity. We show experimentally that the coplanar waveguide cavity acts as a bandpass filter that can significantly reduce the crosstalk signal seen by the second qubit when its frequency is far from the cavity's resonant frequency. We present a simple classical description of the qubit behavior that agrees well with the experimental data. These results suggest that measurement crosstalk between superconducting phase qubits can be reduced by use of linear or possibly nonlinear resonant cavities as coupling elements.Comment: 4 pages, 3 figure

6-Oxo-6-phenyl-6-phospha-3,9-dithiabicyclo[9.4.0]pentadeca-1(11),12,14-triene

The title molecule 6-phenyl-6-phospha-3,9-dithiabicyclo [9.4.0] pentadeca-1(11), 12, 14-triene 6-oxide, C18H21OPS2, has an exodentate conformation, with the S and P atoms oriented away from the centre of the macrocyclic cavity

(Nitrato-κO)(triphenylphosphine-κP){3,6,9-trithiabicyclo[9.4.0]pentadeca-1(11),12,14-triene-κ3S3,6,9}mercury(II) nitrate hydrate hemiethanol solvate

In the title compound [Hg(NO3)(C12H16S3)-(C18H15P)][NO3].H2O.0.5C2H6O, the coordination sphere of the Hg2+ ion is a distorted trigonal bipyramid defined by the three S atoms of the trithiamacrocycle, the P atom of the triphenylphosphine group and an O atom of one nitrate group

Validation of Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) With Long‐Term GOES MAGED Measurements of keV Electron Fluxes at Geostationary Orbit

Surface charging by keV (kiloelectron Volt) electrons can pose a serious risk for satellites. There is a need for physical models with the correct and validated dynamical behavior. The 18.5‐month (2013–2015) output from the continuous operation online in real time as a nowcast of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) is compared to the GOES 13 MAGnetospheric Electron Detector (MAGED) data for 40, 75, and 150 keV energies. The observed and modeled electron fluxes were organized by Magnetic Local Time (MLT) and IMPTAM driving parameters; the observed Interplanetary Magnetic Field (IMF) BZ, BY, and |B|; the solar wind speed VSW; the dynamic pressure PSW; and Kp and SYM‐H indices. The peaks for modeled fluxes are shifted toward midnight, but the ratio between the observed and modeled fluxes at around 06 MLT is close to 1. All the statistical patterns exhibit very similar features with the largest differences of about 1 order of magnitude at 18–24 MLT. Based on binary event analysis, 20–78% of threshold crossings are reproduced, but Heidke skill scores are low. The modeled fluxes are off by a factor of 2 in terms of the median symmetric accuracy. The direction of the error varies with energy: overprediction by 50% for 40 keV, overprediction by 2 for 75 keV, and underprediction by 18% for 150 keV. The revealed discrepancies are due to the boundary conditions developed for ions but used for electrons, absence of substorm effects, representations of electric and magnetic fields which can result in not enough adiabatic acceleration, and simple models for electron lifetimes.Key PointsIMPTAM performs well, with the ratio between the GOES MAGED and modeled keV electron fluxes at 06 MLT close to 1Peaks of IMPTAM fluxes are shifted toward midnight due to the background field models and the sources and losses used inside IMPTAMError is a factor of 2 based on median symmetric accuracy with largest difference of 1 order of magnitude; Heidke skill scores are lowPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149574/1/swe20845_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149574/2/swe20845.pd

Discovery of an Optical Jet in the BL Lac Object 3C 371

We have detected an optical jet in the BL Lac object 3C 371 that coincides with the radio jet in this object in the central few kpc. The most notable feature is a bright optical knot 3 arcsec (4 kpc) from the nucleus that occurs at the location where the jet apparently changes its direction by ~30 degrees. The radio, near-infrared and optical observations of this knot are consistent with a single power-law spectrum with a radio-optical spectral index alpha = -0.81. One possible scenario for the observed turn is that the jet is interacting with the material in the bridge connecting 3C 371 to nearby galaxies and the pressure gradient is deflecting the jet significantly.Comment: 11 pages, LaTeX, 4 figures (1 eps, 3 gifs), accepted for publication in ApJ Letter