First results of electric field and density observations by Cluster EFW based on initial months of operation

International audienceHighlights are presented from studies of the electric field data from various regions along the Cluster orbit. They all point towards a very high coherence for phenomena recorded on four spacecraft that are separated by a few hundred kilometers for structures over the whole range of apparent frequencies from 1 mHz to 9 kHz. This presents completely new opportunities to study spatial-temporal plasma phenomena from the magnetosphere out to the solar wind. A new probe environment was constructed for the CLUSTER electric field experiment that now produces data of unprecedented quality. Determination of plasma flow in the solar wind is an example of the capability of the instrument

Optimization of radial diffusion coefficients for the proton radiation belt during the CRRES era

Proton flux measurements from the Proton Telescope instrument aboard the CRRES satellite are revisited, and used to drive a radial diffusion model of the inner proton belt at 1.1 ≤ L ≤ 1.65. Our model utilises a physics‐based evaluation of the cosmic ray albedo neutron decay (CRAND) source, and coulomb collisional loss is driven by a drift averaged density model combining results from the International Reference Ionosphere, NRLMSIS‐00 atmosphere and Radio Plasma Imager plasmasphere models, parameterised by solar activity and season. We drive our model using time‐averaged data at L = 1.65 to calculate steady state profiles of equatorial phase space density, and optimise our choice of radial diffusion coefficients based on four defining parameters to minimise the difference between model and data. This is first performed for a quiet period when the belt can be assumed to represent steady state. Additionally, we investigate fitting steady state solutions to time averages taken during active periods where the data exhibits limited deviation from steady state, demonstrated by CRRES measurements following the 24th March 1991 storm. We also discuss a way to make the optimisation process more reliable by excluding periods of variability in plasmaspheric density from any time average. Lastly, we compare our resultant diffusion coefficients to those derived via a similar process in previous work, and diffusion coefficients derived for electrons from ground and in situ observations. We find that higher diffusion coefficients are derived compared with previous work, and suggest more work is required to derive proton diffusion coefficients for different geomagnetic activity levels

Control of ULF wave accessibility to the inner magnetosphere by the convection of plasma density

During periods of storm activity and enhanced convection, the plasma density in theafternoon sector of the magnetosphere is highly dynamic due to the development of plasmasphericdrainage plume (PDP) structure. This significantly affects the local Alfvén speed and alters the propagationof ULF waves launched from the magnetopause. Therefore, it can be expected that the accessibility of ULFwave power for radiation belt energization is sensitively dependent on the recent history of magnetosphericconvection and the stage of development of the PDP. This is investigated using a 3-D model for ULF waveswithin the magnetosphere in which the plasma density distribution is evolved using an advection model forcold plasma, driven by a (VollandStern) convection electrostatic field (resulting in PDP structure). The wavemodel includes magnetic field day/night asymmetry and extends to a paraboloid dayside magnetopause,from which ULF waves are launched at various stages during the PDP development. We find that the plumestructure significantly alters the field line resonance location, and the turning point for MHD fast waves,introducing strong asymmetry in the ULF wave distribution across the noon meridian. Moreover, thedensity enhancement within the PDP creates a waveguide or local cavity for MHD fast waves, such thateigenmodes formed allow the penetration of ULF wave power to much lower L within the plume thanoutside, providing an avenue for electron energization

Transport of the plasma sheet electrons to the geostationary distances

The transport and acceleration of low‐energy electrons (50–250 keV) from the plasma sheet to the geostationary orbit were investigated. Two moderate storm events, which occurred on 6–7 November 1997 and 12–14 June 2005, were modeled using the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM) with the boundary set at 10  R E in the plasma sheet. The output of the IMPTAM was compared to the observed electron fluxes in four energy ranges (50–225 keV) measured by the Synchronous Orbit Particle Analyzer instrument onboard the Los Alamos National Laboratory spacecraft. It was found that the large‐scale convection in combination with substorm‐associated impulsive fields is the drivers of the transport of plasma sheet electrons from 10  R E to geostationary orbit at 6.6  R E during storm times. The addition of radial diffusion had no significant influence on the modeled electron fluxes. At the same time, the modeled electron fluxes are one (two) order(s) smaller than the observed ones for 50–150 keV (150–225 keV) electrons, respectively, most likely due to inaccuracy of electron boundary conditions. The loss processes due to wave‐particle interactions were not considered. The choice of the large‐scale convection electric field model used in simulations did not have a significant influence on the modeled electron fluxes, since there is not much difference between the equipotential contours given by the Volland‐Stern and the Boyle et al . (1997) models at distances from 10 to 6.6  R E in the plasma sheet. Using the TS05 model for the background magnetic field instead of the T96 model resulted in larger deviations of the modeled electron fluxes from the observed ones due to specific features of the TS05 model. The increase in the modeled electron fluxes can be as large as two orders of magnitude when substorm‐associated electromagnetic fields were taken into account. The obtained model distribution of low‐energy electron fluxes can be used as an input to the radiation belt models. This seed population for radiation belts will affect the local acceleration up to relativistic energies. Key Points Transport of plasma sheet electrons due to convection and substorms Importance of boundary conditions in plasma sheet Importance of magnetic field model choicePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97187/1/jgra50047.pd

ULF wave activity in the magnetosphere: resolving solar wind interdependencies to identify driving mechanisms

Ultra-low frequency (ULF) waves in the magnetosphere are involved in the energisation and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine fifteen years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to $L \sim 6.6 R_E$). We determine the relative contribution to ULF wave power from instantaneous non-derived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed $v_{sw}$, southward interplanetary magnetic field component $B_z < 0$ and summed power in number density perturbations $\delta N_p$. Together, the subordinate parameters $B_z$ and $\delta N_p$ still account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters

Frequency spectrum of toroidal Alfv\'en mode in a neutron star with Ferraro's form of nonhomogeneous poloidal magnetic field

Using the energy variational method of magneto-solid-mechanical theory of a perfectly conducting elastic medium threaded by magnetic field, the frequency spectrum of Lorentz-force-driven global torsional nodeless vibrations of a neutron star with Ferraro's form of axisymmetric poloidal nonhomogeneous internal and dipole-like external magnetic field is obtained and compared with that for this toroidal Alfv\'en mode in a neutron star with homogeneous internal and dipolar external magnetic field. The relevance of considered asteroseismic models to quasi-periodic oscillations of the X-ray flux during the ultra powerful outbursts of SGR 1806-20 and SGR 1900+14 is discussed.Comment: Accepted for publication in Astrophysics & Space Scienc

Bad Language in Reality: A study of swear words, expletives and gender in reality television

This essay is a study on swearing in modern English on television from a sociolinguistic point of view, taking into account the effect that variables such as nationality, social class and gender might have on the expletive usage in the examined material. After a general discussion of expletives and their functions, the question of whether there is a relationship between gender and the use of expletives is addressed. A review of previous research on the subject suggests a difference in opinion between traditional sociolinguistic studies, in which the differences between male and female speech have often been highlighted, and where female speech has been characterized as more polite, aiming for standard language and avoiding expletives, while modern feminist critics argue that these are stereotypes perpetuated through the ages which have little support of empirical evidence. The second half of the paper reports the results from an investigation on the use of expletives in two reality television programs with the same basic features; one American – Jersey Shore, and one British – Geordie Shore. The results of this investigation seem to contradict the stereotypical notions of women as less prone to use expletives than men. Possible reasons for this, including group identity and social class, are discussed

Svengelska och engelska importord i nutidssvenskan

Syftet med denna uppsats är att undersöka förekomsten av engelska importord i vardagligt svenskt språkbruk. Genom att undersöka ett material bestående av tidningstext från gratisdagstidningen Metro försöker jag kartlägga utbredningen och förklara användningen av nyare engelska lånord i en för övrigt svensk kontext. Som referensverk över vilka ord som kan klassas som nya importord använder jag SAOL 13 och de påträffade lånord som redan finns med däri inkluderas inte i undersökningen. Resultatet visar att flest lånord förekommer i samma ämneskategorier som uppmärksammats i tidigare undersökningar; Mode och skönhet, Musik och nöje, Film och TV, Sport och fritid, Mat och hälsa samt Teknik och motor. Flest tillfälliga lån återfinns i friare texttyper som krönikor, där det är vanligt att fritt blanda språken utan att signalera detta med något slags markörer. I nyhetsartiklar och texter med allvarligt innehåll är det däremot mycket ovanligt att hitta nyare lånord av något slag. I de fall när lånord förekommer i den senare textkategorin är de oftast försedda med markörer som citationstecken, s.k. eller efterföljande översättning till svenska. De nya lånenorden anpassas mer sällan till svenska stavnings- och böjningsmönster än tidigare lån och i de flesta fall där en svensk motsvarighet förekommer föredras ändå det engelska ordet. Överlag verkar det finnas en attitydskillnad i hur man förhåller sig till lånorden jämfört med tidigare undersökningar, där det nu finns en större acceptans av både importord och en språklig blandning som ibland sträcker sig så långt som att till synes sudda ut gränserna mellan grundspråk och lånespråk.Specialarbete 15 poäng Titel: Svengelska och engelska importord i nutidssvenskan Författare: Anna Fälthammar Schippers Termin och år: Höstterminen 2014 Kursansvarig institution: Institutionen för svenska språket Handledare: Maja Lindfors Examinator: Richard Johansso