1,722,338 research outputs found
Collaborative Research Activities of the Arase and Van Allen Probes
No full textThis paper presents the highlights of joint observations of the inner magnetosphere by the Arase spacecraft, the Van Allen Probes spacecraft, and ground-based experiments integrated into spacecraft programs. The concurrent operation of the two missions in 2017–2019 facilitated the separation of the spatial and temporal structures of dynamic phenomena occurring in the inner magnetosphere. Because the orbital inclination angle of Arase is larger than that of Van Allen Probes, Arase collected observations at higher L-shells up to L∼10. After March 2017, similar variations in plasma and waves were detected by Van Allen Probes and Arase. We describe plasma wave observations at longitudinally separated locations in space and geomagnetically-conjugate locations in space and on the ground. The results of instrument intercalibrations between the two missions are also presented. Arase continued its normal operation after the scientific operation of Van Allen Probes completed in October 2019. The combined Van Allen Probes (2012-2019) and Arase (2017-present) observations will cover a full solar cycle. This will be the first comprehensive long-term observation of the inner magnetosphere and radiation belts.journal articl
Trained BERT models for phrase alignment with the constrained tree edit distance algorithm
No full text<p>These are the trained BERT models for phrase alignment with the constrained tree edit distance algorithm, published at EMNLP2020.</p>
<p>Yuki Arase and Jun'ichi Tsujii. 2020. <a href="https://www.aclweb.org/anthology/2020.emnlp-main.125/">Compositional Phrase Alignment and Beyond</a>. in Proc. of the Conference on Empirical Methods in Natural Language Processing (EMNLP), pp. 1611-1623.</p>
<p>Source codes are available at <a href="https://github.com/yukiar/phrase_alignment_cted">GitHub</a></p>
<p>When you use these models, please cite the following paper.</p>
<p>@inproceedings{arase-tsujii-2020-compositional,<br>
title = "Compositional Phrase Alignment and Beyond",<br>
author = "Arase, Yuki and<br>
Tsujii, Jun{'}ichi",<br>
booktitle = "Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)",<br>
month = nov,<br>
year = "2020",<br>
address = "Online",<br>
publisher = "Association for Computational Linguistics",<br>
url = "https://www.aclweb.org/anthology/2020.emnlp-main.125",<br>
doi = "10.18653/v1/2020.emnlp-main.125",<br>
pages = "1611--1623"<br>
}</p>
<p> </p>
Geant4 simulation of ARASE HEP instrument calibration
No full textThis dataset created for the calibration of ARASE HEP instruments. The Geant4 particle simulation results contained in this data. The format of this data is root. The root analysis tool needs to be required to see this data
[Former California biochemistry student Tom Arase]
No full textFormer California biochemistry student Tom Arase performs gastro analysis in hospital laboratory at Jerome incarceration camp March 3, 1943. Photo by Tom Parker.The TOMO Foundation in Illinois donated the collection, which contains documents by and about the Japanese-American experience during World War II
Preliminary Statistical Comparisons of Spin‐Averaged Electron Data From Arase and Van Allen Probes Instruments
No full textFollowing the end of the Van Allen Probes mission, the Arase satellite offers a unique opportunity to continue in‐situ radiation belt and ring current particle measurements into the next solar cycle. In this study we compare spin‐averaged flux measurements from the MEPe, HEP‐L, HEP‐H, and XEP‐SSD instruments on Arase with those from the MagEIS and REPT instruments on the Van Allen Probes, calculating Pearson correlation coefficient and the mean ratio of fluxes at L* conjunctions between the spacecraft. Arase and Van Allen Probes measurements show a close agreement over a wide range of energies, observing a similar general evolution of electron flux, as well as average, peak, and minimum values. Measurements from the two missions agree especially well in the 3.6 = L* ≤ 4.4 range where Arase samples similar magnetic latitudes to Van Allen Probes. Arase tends to record higher flux for energies 1.4 MeV, Arase flux measurements are generally lower than those of Van Allen Probes, especially for L* > 4.4. The correlation coefficient values show that the >1.4 MeV flux from both missions are well correlated, indicating a similar general evolution, although flux magnitudes differ. We perform a preliminary intercalibration between the two missions using the mean ratio of the fluxes as an energy‐ and L*‐ dependent intercalibration factor. The intercalibration factor improves agreement between the fluxes in the 0.58–1 MeV range.Key Points:
MEPe, HEPH, HEPL, XEPSSD, and MAGEIS/REPT show a good correlation at energies above 300 keV and 3 < L* < 4.6.
Flux measurements at the same energy from the two missions are highly comparable in magnitude.
Intercalibration via energy‐ and L*‐dependent factors improves the agreement between Arase and RBSP.Camargo Foundation
http://dx.doi.org/10.13039/501100001666EC, Horizon 2020 Framework Programme (H2020)
http://dx.doi.org/10.13039/100010661Deutsche Forschungsgemeinschaft (DFG)
http://dx.doi.org/10.13039/50110000165
Statistical Survey of Arase Satellite Data Sets in Conjunction With the Finnish Riometer Network
No full textAbstractDuring disturbed geomagnetic conditions, the energetic particles in the inner magnetosphere are known to undergo precipitation loss due to interaction with various plasma waves. This study, investigates the energetic particle precipitation events statistically using coordinate observations from the ground riometer network and the inner-magnetospheric satellite mission, Arase. We have compared cosmic noise absorption (CNA) data obtained from the Finnish ground riometer network located in the auroral/sub-auroral latitudes with the comprehensive data set of omnidirectional electron/proton flux and plasma waves in ELF/VLF frequency range from the Arase satellite during the overpass intervals. The study period includes one and a half years of data between March 2017 and September 2018 covering Arase conjunctions with the riometer stations from all magnetic local time sectors. The relation between the plasma flux/waves observed at the satellite with the riometer absorptions are investigated statistically for CNA (absorption >0.5 dB) and non-CNA (absorption Abstract
During disturbed geomagnetic conditions, the energetic particles in the inner magnetosphere are known to undergo precipitation loss due to interaction with various plasma waves. This study, investigates the energetic particle precipitation events statistically using coordinate observations from the ground riometer network and the inner-magnetospheric satellite mission, Arase. We have compared cosmic noise absorption (CNA) data obtained from the Finnish ground riometer network located in the auroral/sub-auroral latitudes with the comprehensive data set of omnidirectional electron/proton flux and plasma waves in ELF/VLF frequency range from the Arase satellite during the overpass intervals. The study period includes one and a half years of data between March 2017 and September 2018 covering Arase conjunctions with the riometer stations from all magnetic local time sectors. The relation between the plasma flux/waves observed at the satellite with the riometer absorptions are investigated statistically for CNA (absorption >0.5 dB) and non-CNA (absorption <0.5 dB) cases separately. During CNA events, Arase observed elevated electron flux in the medium energy range (2–100 keV), and plasma wave activity in the whistler-mode frequency range (0.5–3 kHz) of the spectra. Our study provides an estimate of the statistical dependence of the electron flux and plasma wave observations at Arase with the ground reality of actual precipitation
Statistical survey of Arase satellite data sets in conjunction with the Finnish riometer network
No full textAbstract
During disturbed geomagnetic conditions, the energetic particles in the inner magnetosphere are known to undergo precipitation loss due to interaction with various plasma waves. This study, investigates the energetic particle precipitation events statistically using coordinate observations from the ground riometer network and the inner-magnetospheric satellite mission, Arase. We have compared cosmic noise absorption (CNA) data obtained from the Finnish ground riometer network located in the auroral/sub-auroral latitudes with the comprehensive data set of omnidirectional electron/proton flux and plasma waves in ELF/VLF frequency range from the Arase satellite during the overpass intervals. The study period includes one and a half years of data between March 2017 and September 2018 covering Arase conjunctions with the riometer stations from all magnetic local time sectors. The relation between the plasma flux/waves observed at the satellite with the riometer absorptions are investigated statistically for CNA (absorption >0.5 dB) and non-CNA (absorption <0.5 dB) cases separately. During CNA events, Arase observed elevated electron flux in the medium energy range (2–100 keV), and plasma wave activity in the whistler-mode frequency range (0.5–3 kHz) of the spectra. Our study provides an estimate of the statistical dependence of the electron flux and plasma wave observations at Arase with the ground reality of actual precipitation
Multi‐Event Analysis of Magnetosphere‐Ionosphere Coupling of Nighttime Medium‐Scale Traveling Ionospheric Disturbances From the Ground and the Arase Satellite
No full textAbstractKawai et al. (2021) reported the first ground-satellite conjugate observation of nighttime medium-scale traveling ionospheric disturbances (MSTIDs), by analyzing measurements from an airglow imager at Gakona (geographic latitude: 62.39°N, geographic longitude: 214.78°E, magnetic latitude: 63.60°N) and the Arase satellite in the magnetosphere on 3 November 2018. The Arase satellite observed variations in both the polarization electric field and the electron density as the Arase footprint passed through the MSTID structures in the ionosphere. In this study, we investigated whether these electric field and density variations associated with MSTIDs at subauroral latitudes are always observed by Arase in the magnetosphere. We used three airglow imagers installed at Gakona, Athabasca (geographic latitude: 54.60°N, geographic longitude: 246.36°E, magnetic latitude: 61.10°N), and Kapuskasing (geographic latitude: 49.39°N, geographic longitude: 277.81°E, magnetic latitude: 58.70°N) and the Arase satellite. We found eight observations of MSTIDs conjugate with Arase. They indicate that electric field and density variations associated with MSTIDs are not always observed in the magnetosphere. These variations tend to be observed in the magnetosphere during geomagnetically quiet times and when the amplitude of the MSTID is large. We categorized the MSTIDs into those caused by plasma instabilities and gravity waves and found that the electric field and density variations can be observed in the magnetosphere for both types of MSTIDs.Abstract
Kawai et al. (2021) reported the first ground-satellite conjugate observation of nighttime medium-scale traveling ionospheric disturbances (MSTIDs), by analyzing measurements from an airglow imager at Gakona (geographic latitude: 62.39°N, geographic longitude: 214.78°E, magnetic latitude: 63.60°N) and the Arase satellite in the magnetosphere on 3 November 2018. The Arase satellite observed variations in both the polarization electric field and the electron density as the Arase footprint passed through the MSTID structures in the ionosphere. In this study, we investigated whether these electric field and density variations associated with MSTIDs at subauroral latitudes are always observed by Arase in the magnetosphere. We used three airglow imagers installed at Gakona, Athabasca (geographic latitude: 54.60°N, geographic longitude: 246.36°E, magnetic latitude: 61.10°N), and Kapuskasing (geographic latitude: 49.39°N, geographic longitude: 277.81°E, magnetic latitude: 58.70°N) and the Arase satellite. We found eight observations of MSTIDs conjugate with Arase. They indicate that electric field and density variations associated with MSTIDs are not always observed in the magnetosphere. These variations tend to be observed in the magnetosphere during geomagnetically quiet times and when the amplitude of the MSTID is large. We categorized the MSTIDs into those caused by plasma instabilities and gravity waves and found that the electric field and density variations can be observed in the magnetosphere for both types of MSTIDs
Flux Enhancements in the Inner Magnetosphere Observed by Arase
No full textThe present study examines the low-energy ion flux variations observed by the Arase satellite in the inner magnetosphere. From the magnetic field and ion flux data obtained by the fluxgate magnetometer and the low-energy particle experiments–ion mass analyzer onboard Arase, we find 55 events of the low-energy O^+ flux enhancement accompanied with magnetic field dipolarization in the periods of April 1–October 31, 2017 and July 1, 2018–January 31, 2019. The low-energy O^+ flux enhancements (a) start a few minutes after the dipolarization onset, (b) have energy-dispersed signatures with decreasing energy from a few keV down to ∼10 eV, (c) are observed in both storm and non-storm periods, (d) have a field-aligned distribution (α ∼ 0° in the southern hemisphere and α ∼ 180° in the northern hemisphere), (e) are accompanied by the low-energy H^+ flux enhancements that have lower energies than O^+ by a factor of 3–10, and (f) increase the O^+ density and the O^+/H^+ density ratio by ∼10 times and 4–5 times, respectively. We perform a numerical simulation to trace ion trajectories forward in time from the Arase positions. It is revealed that both H^+ and O^+ ions drift eastward and reach the dawn-to-morning sector without being lost in the ionosphere, if the pitch angle scattering effect is considered near the equatorial plane. This result suggests that these low-energy field-aligned ions can contribute to formation of the warm plasma cloak.journal articl
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