Interhemispheric differences in the HF radar signature of the cusp region: A review through the study of a case example

This paper aims to provide a review of our understanding of the HF radar signatures of the cusp and transient magnetopause reconnection phenomena through the study of a case example. Two Super DARN radars observe the conjugate cusp regions during an interval of southward IMF. These observations allow us to determine several parameters relating to the electrodynamics of the magnetopause reconnection process, including the mean reconnection voltage and the reconnection electric fields and X-line lengths in the two hemispheres. In addition, we identify several differences between the radar and flow signatures observed in the two hemispheres, specifically that flux transfer event signatures are observed in the Northern Hemisphere but not the Southern Hemisphere, and that the azimuthal component of the flow excited by reconnection is much greater in the Southern Hemisphere than in the Northern Hemisphere. We finish our discussion by identifying remaining questions regarding the interpretation of HF radar observations of the cusp

An explicit IMF By dependence on solar wind ‐ magnetosphere coupling

Presently, all empirical coupling functions quantifying the solar wind—magnetosphere energy—or magnetic flux conversion assume that the coupling is independent of the sign of the dawn-dusk component (B) of the Interplanetary Magnetic Field (IMF). In this paper we present observations strongly suggesting an explicit IMF B effect on the solar wind-magnetosphere coupling. When the Earth's dipole is tilted in the direction corresponding to northern winter, positive IMF B is found to on average lead to a larger polar cap than when IMF B is negative during otherwise similar conditions. This explicit IMF B effect is found to reverse when the Earth's dipole is inclined in the opposite direction (northern summer) and is consistently observed from both hemispheres. We interpret the different responses of the polar cap size due to the sign of IMF B to likely be a result of differences in the dayside reconnection rate.publishedVersio

Observations of large flow shears around small-scale auroral beads observed at substorm onset

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月16日（水） 統計数理研究所 3階リフレッシュフロ

Conducting interfaces between band insulating oxides: the LaGaO3/SrTiO3

We show that the growth of the heterostructure LaGaO3/SrTiO3 yields the formation of a highly conductive interface. Our samples were carefully analyzed by high resolution electron microscopy, in order to assess their crystal perfection and to evaluate the abruptness of the interface. Their carrier density and sheet resistance are compared to the case of LaAlO3/SrTiO3 and a superconducting transition is found. The results open the route to widening the field of polar-non polar interfaces, pose some phenomenological constrains to their underlying physics and highlight the chance of tailoring their properties for future applications by adopting suitable polar materials.Comment: in press Appl. Phys. Lett. 97, 1 (2010

Characteristics of travelling ionospheric disturbances observed by SuperDARN during various levels of geomagnetic activity

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日（月） 国立極地研究所 2階大会議

Aurora in the Polar Cap: A Review

This paper reviews our current understanding of auroral features that appear poleward of the main auroral oval within the polar cap, especially those that are known as Sun-aligned arcs, transpolar arcs, or theta auroras. They tend to appear predominantly during periods of quiet geomagnetic activity or northwards directed interplanetary magnetic field (IMF). We also introduce polar rain aurora which has been considered as a phenomenon on open field lines. We describe the morphology of such auroras, their development and dynamics in response to solar wind-magnetosphere coupling processes, and the models that have been developed to explain them

Payload Testing of a Weak Coherent Pulse Quantum Key Distribution Module for the Responsive Operations on Key Services (ROKS) Mission

Quantum Key Distribution (QKD) missions currently in development for space are expanding in number due to the increasing need for more secure means of encryption combined with the range limitations of terrestrial QKD. Most of these new missions are using smaller satellites to test their payloads. The ROKS (Responsive Operations for Key Services) mission is one such mission. It will utilize a 6U CubeSat bus and is set to launch in Q4 2022. A breadboard model of a 785nm weak coherent pulse quantum source module designed for ROKS, named JADE, was tested within a lab testbench environment with the mission’s systems represented by breadboard models with equivalent components. JADE’s optical module was miniaturized to be compatible with the limited payload volumes of these small classes of satellites. Lab-based testbench characterization of JADE’s ability to emit quantum pulses with four polarization states that propagate through the beam steering system for analysis by a receiver box was demonstrated. Future work will focus on further shrinking the JADE module down to less than 1/3U size, increasing the interoperability of the module with standard interfaces for both CubeSats and SmallSats, and adding further capabilities and full environmental testing qualification to JADE

Do statistical models capture the dynamics of the magnetopause during sudden magnetospheric compressions?

Under periods of strong solar wind driving, the magnetopause can become compressed, playing a significant role in draining electrons from the outer radiation belt. Also termed “magnetopause shadowing,” this loss process has traditionally been attributed to a combination of magnetospheric compression and outward radial diffusion of electrons. However, the drift paths of relativistic electrons and the location of the magnetopause are usually calculated from statistical models and, as such, may not represent the time‐varying nature of this highly dynamic process. In this study, we construct a database ∼20,000 spacecraft crossings of the dayside magnetopause to quantify the accuracy of the commonly used Shue et al. (1998, https://doi.org/10.1029/98JA01103) model. We find that, for the majority of events (74%), the magnetopause model can be used to estimate magnetopause location to within ±1 RE. However, if the magnetopause is compressed below 8 RE, the observed magnetopause is greater than 1 RE inside of the model location on average. The observed magnetopause is also significantly displaced from the model location during storm sudden commencements, when measurements are on average 6% closer to the radiation belts, with a maximum of 42%. We find that the magnetopause is rarely close enough to the outer radiation belt to cause direct magnetopause shadowing, and hence rapid outward radial transport of electrons is also required. We conclude that statistical magnetopause parameterizations may not be appropriate during dynamic compressions. We suggest that statistical models should only be used during quiescent solar wind conditions and supplemented by magnetopause observations wherever possible