Relation between the asymmetric ring current effect and the anti-sunward auroral currents, as deduced from CHAMP observations

During magnetically active periods the storm-time disturbance signal on the ground commonly develops an azimuthal asymmetry. Negative deflections of the magnetic horizontal (H) component are enhanced in the 18:00 local time sector and smallest in the morning sector. This is commonly attributed to the asymmetric ring current effect. In this study we investigate the average characteristics of anti-sunward net currents that are not closing in the ionosphere. Their intensity is growing proportionally with the amount of solar wind input to the magnetosphere. There is almost twice as much current flowing across the polar region in the winter hemisphere as on the summer side. This seasonal dependence is more pronounced in the dusk sector than in the dawn sector. Event studies reveal that anti-sunward currents are closely related to the main phase of a magnetic storm. Since the asymmetry of storm-time disturbances also builds up during the main phase, we suggest a relation between these two phenomena. From a statistical study of ground-based disturbance levels during magnetically active periods, we obtain support for our suggestion. We propose a new 3D current system responsible for the zonally asymmetric storm-time disturbance signal that does not involve the ring current. The high-latitude anti-sunward currents are connected at their noon and midnight ends to field-aligned currents that lead the currents to the outer magnetosphere. The auroral net current branch on the morning side is closed along the dawn flank near the magnetopause, and the evening side currents flow along the dusk flank magnetosphere. Regardless through which loop the current is flowing, near-Earth storm-time disturbance levels will in both cases be reduced in the morning sector and enhanced in the evening.

Minor Ion and Electron Characteristics within Magnetosheath Flux Transfer Events Observed by the Magnetospheric Multiscale Mission

<p>Several dayside magnetosheath flux transfer events (FTEs) have been observed at high temporal resolution by the four-spacecraft MMS mission. In this study, we examine ion energy spectrograms, ion moments, and ion distribution functions for several long duration magnetosheath FTEs observed by MMS. For these cases, the spacecraft were positioned at similar locations (i.e., south of the equatorial plane, post-noon local time sector). The ion observations are placed in context with electron energy spectrograms parallel and anti-parallel to the observed magnetic field and the location of MMS relative to the predicted reconnection line location as determined from convected solar wind conditions. This combined set of observations provide important information on the formation, topologies, and evolution of FTEs.</p>

Relation between the asymmetric ring current effect and the anti-sunward auroral currents, as deduced from CHAMP observations

During magnetically active periods the storm-time disturbance signal on ground develops commonly an azimuthal asymmetry. Negative deflections of the magnetic horizontal (H) component are enhanced in the 18:00 local time sector and smallest in the morning sector. This is commonly attributed to the asymmetric ring current effect. In this study we are investigating the average characteristics of anti-sunward net currents that are not closing in the ionosphere. Their intensity is growing proportionally with the amount of solar wind input to the magnetosphere. There is almost twice as much current flowing in the winter hemisphere as on the summer side. This seasonal dependence is more pronounced on the dusk than on the dawn side. Event studies reveal that anti-sunward currents are closely related to the main phase of a magnetic storm. Since also the asymmetry of storm-time disturbances build up during the main phase, we suggest a relation between these two phenomena. From a statistical study of ground-based disturbance levels during magnetically active periods we obtain support for our suggestion. Observed storm-time disturbance amplitudes are clearly smaller in the summer hemisphere than in the winter part. This difference increases toward higher latitudes. We propose a new 3D current system responsible for the zonally asymmetric storm-time disturbance signal that does not involve the ring current. The high-latitude anti-sunward currents are connected at their noon and midnight ends to field-aligned currents that lead the currents to the outer magnetosphere. The net current branch on the morning side is closed along the dawn flank plasmapause, and the evening side currents along the dusk flank magnetopause. Regardless through which loop the current is flowing, near-Earth storm-time disturbance level will in both cases be reduced in the morning sector and enhanced in the evening.

Evidence for diurnal periodicity of earthquakes from midnight to daybreak

Previously, inadequate earthquake catalogs and the lack of method made it challenging, if not impossible, to determine the dominant period of earthquake occurrence. With the advent of densely distributed seismic stations in Japan since 2002, 410 642 M1.0+ earthquakes have been cataloged under the mainland within 30-km depth, which provide a superb dataset to identify the periodicity of earthquakes. We processed this catalog using time-frequency analyses and daily stacking, which are powerful in extracting weak periodical signal from strong random noises. We concentrated on the time sector from 0:00 to 6:00 (i.e. from midnight to daybreak), which is a reliable time window for much higher detectability of weak earthquakes, since it has the lowest affects from cultural noises. We successfully observed two apparent periodicities of 12- and 24-hour, which are much smaller than the fortnightly periodicity presented previously in the literature. Synthetic earth tides, after intentionally ignoring the contribution from the Moon, present similar dominant periods as the earthquakes. This may indicate that the dominant period of earthquakes is statistically associated with the Sun rather than the Moon. The daily stacking number of earthquakes using a 15-minute or 1-hour interval shows a peak around 1:30, rather than usually expected 3:00 to 4:00. In addition, bigger earthquakes show more evident variations in the stacking results, and the trend is very consistent for various lower limits of earthquake magnitude from M1.0 to M4.0. These discoveries settled the disputes on the existence of the periodicity of earthquakes since 1886 and may open a window to unravel the mystery of earthquakes.

The Outcomes of Investment Treaty Arbitration

This chapter explores variations in dispute outcomes in investment treaty arbitration. Building on the literature on political institutions, the study places the theoretical importance of actor information about the rules of the game and the resources of the participants at the centre of analysis. Such information shapes the strategy of the players and their relative ability to compete successfully, establishing the basis for hypotheses about variations in dispute outcomes. Drawing on the universe of known disputes, the analysis relies on statistical models and data capable of addressing concurrently the full range of potential dispute outcomes rather than particular categories of wins and losses. States do not just win or lose treaty-based investment disputes; disputes can also be concluded by decisions to discontinue arbitral proceedings and by settlements negotiated between states and investors prior to an arbitral award. Consistent with theoretical expectation, the findings indicate that dispute outcomes vary in response to the evolution of the system of dispute settlement over time, sector of investment, and access to international legal expertise, thereby underlining the pivotal role of information flows in investment dispute settlement.

Classical and quantum wormholes in a 5D compact Kaluza–Klein theory

We study the classical and quantum euclidean wormholes for an empty (4+1) dimensional Kaluza–Klein universe with a positive cosmological constant and a spatially flat Robertson–Walker type metric. It is shown that classical wormholes do not exist neither for the space–time sector nor the extra dimensional sector of this model, but two spectra of quantum wormholes as the solutions of the Wheeler–DeWitt equation exist that are consistent with the Hawking–Page conjecture about the necessary boundary conditions. In the spectrum where the external scale factor R shapes the quantum wormholes the internal scale factor a may play the role of effective matter source, and in the spectrum where the internal scale factor a shapes the quantum wormholes the external scale factor R may play the role of effective matter source.

Experimental evidence of the simultaneous occurrence of VLF chorus on the ground in the global azimuthal scale – from pre-midnight to the late morning

Night-time VLF (very low frequency) chorus bursts lasting about one hour have been recorded at Finnish temporal station Kannuslehto (CGM: 64.2°; 107.9°, L = 5.3) during two VLF campaigns (on 25 February–4 March 2008 and 27 March–17 April 2011). The chorus bursts were associated with substorm development. They were accompanied by riometer absorption enhancements, which occurred simultaneously within as large longitude areas as from pre-midnight (Sodankylä, ~22:00 MLT) to the late morning (Tixie, ~03:00 MLT and Gakona, ~08:00 MLT) longitudes. It was found that the pre-midnight chorus observed on the ground occurred simultaneously with VLF chorus emissions recorded in the late morning on the low-altitude DEMETER satellite crossing the similar geomagnetic latitudes on the opposite local time sector. For the first time some evidence of simultaneous chorus burst generation in the global longitudinal scale was found (from pre-midnight to the late morning) by using direct comparison with satellite data as well as using non-direct indicator–azimuthally extended riometer absorption enhancements.