2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM)最新文献_第4页

Analysis of Conjugate Satellite and Ground EMIC Wave Observations 卫星与地电磁波共轭观测分析

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552374

M. Usanova, L. Blum

{"title":"Analysis of Conjugate Satellite and Ground EMIC Wave Observations","authors":"M. Usanova, L. Blum","doi":"10.23919/USNC-URSIRSM52661.2021.9552374","DOIUrl":"https://doi.org/10.23919/USNC-URSIRSM52661.2021.9552374","url":null,"abstract":"Electromagnetic ion cyclotron (EMIC) waves are transverse electromagnetic waves typically generated in the equatorial magnetosphere by anisotropic proton distributions. These waves can resonantly interact with multiple particle populations in the inner magnetosphere believed to be an important loss mechanism for both ring current ions and radiation belt electrons, as well as a cold plasma heating source. The spatiotemporal extent of wave activity is one of the key parameters used to quantify the effects of EMIC waves on magnetospheric plasma populations. However, from single-point spacecraft measurements or ground based observations alone, it is challenging to get the full picture of wave occurrence distributions. Due to a number of processes, ground and in situ observations of EMIC wave activity, specifically, its global occurrence, duration, and frequency often exhibit noticeable variations [1]. In particular, EMIC waves in the H+ frequency band are not always seen on the ground conjugately to locations of space observations [2]. In addition, ground and space EMIC wave distributions have different dependencies on local time, L shell, and geomagnetic activity, adding to the challenge of comparing measurements across these platforms [3]. Here we address this challenge by examining the relationship between EMIC wave occurrence and power on the Van Allen Probes and conjugate CARISMA ground magnetometer stations in the Canadian sector. We apply an automated wave detection algorithm to magnetometer data [4]. We present an analysis of long-term simultaneous EMIC wave observations in space and on the ground, and study wave propagation characteristics in the He+ and H+ frequency bands during different geomagnetic conditions.","PeriodicalId":365284,"journal":{"name":"2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116224425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

New perspectives on radiation belt precipitation from the ELFIN CubeSats ELFIN立方体卫星辐射带降水的新视角

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552364

D. Turner, C. Wilkins, Wen Li, V. Angelopoulos

{"title":"New perspectives on radiation belt precipitation from the ELFIN CubeSats","authors":"D. Turner, C. Wilkins, Wen Li, V. Angelopoulos","doi":"10.23919/USNC-URSIRSM52661.2021.9552364","DOIUrl":"https://doi.org/10.23919/USNC-URSIRSM52661.2021.9552364","url":null,"abstract":"The Electron Losses and Fields Investigation (ELFIN) is a satellite mission 1 launched in 2018 consisting of two, identical 3U CubeSats in circular, polar LEO orbit at altitudes ~450 km. Onboard each spacecraft, the ELFIN prime payloads consist of energetic particle telescopes and boom-deployed fluxgate magnetometers. Each orbit, ELFIN observes energetic electrons ranging from 50 keV to 7 MeV precipitating from Earth's radiation belts, and ELFIN presents the opportunity to study such radiation belt losses in unprecedented energy resolution with multipoint observations that enable some disambiguation of spatiotemporal evolution. Furthermore, the ELFIN spacecraft are spinners, revealing for the first time details of electron pitch angle distributions within the atmospheric loss cones. In this talk, we will introduce the ELFIN mission and system and payloads. Next, we present new results from ELFIN highlighting several enlightening features of outer radiation belt precipitation, including: energy spectra of> 1 MeV precipitation events and microbursts; spatial structure and temporal evolution of precipitation bands; evidence of localized regions of enhanced precipitation, presumably from chorus wave activity just outside the plasmapause; quantification of steady “drizzle” of electrons into the atmospheric loss cones vs. enhanced, time-limited microbursts and precipitation bands; and quantification of atmospheric backscatter of precipitating electrons. All of these are new insights enabled by the unique observations made possible from the multipoint ELFIN mission.","PeriodicalId":365284,"journal":{"name":"2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123844696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Target counting and location detection in electromagnetics using convolutional neural networks 基于卷积神经网络的电磁学目标计数和定位检测

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552343

Mohsen Sabbaghi, Jun Zhang, G. Hanson

引用次数: 0

Boundaries and enhancements: ULF wave-driven dynamics of energetic particles in the Van Allen belts 边界和增强:范艾伦带中高能粒子的超光速波驱动动力学

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552344

Allison N. Javnes, Jayasri Joseph, Joshua Doucette, D. Baker, Xinlin Li, S. Kanekal

{"title":"Boundaries and enhancements: ULF wave-driven dynamics of energetic particles in the Van Allen belts","authors":"Allison N. Javnes, Jayasri Joseph, Joshua Doucette, D. Baker, Xinlin Li, S. Kanekal","doi":"10.23919/USNC-URSIRSM52661.2021.9552344","DOIUrl":"https://doi.org/10.23919/USNC-URSIRSM52661.2021.9552344","url":null,"abstract":"High-energy electron populations within the Van Allen radiation belts are highly dynamic, and seen to increase and decrease on timescales as short as hours. One of the lingering questions about radiation belt dynamics overall is which types of plasma waves are responsible for the various changes we observe. Here, we present two studies that illuminate how ULF waves shape the boundaries and enhancements of relativistic electrons. One result, using seven years of Van Allen Probes satellite data, shows that ULF waves can create multi-MeV flux enhancements following geomagnetically active periods. Thus, ULF-driven radial diffusion can often be the dominant mechanism behind ultrarelativistic electron enhancements; although high populations of lower energies, likely produced by VLF interactions, are a necessary precondition. A second analysis, looking at decades of POES data, shows that relativistic breaches of the lower boundary of the outer belt happen in concert with elevated ULF wave power yet are not associated with particular type of solar driving. How relativistic electrons can cross this barrier and enter into the slot region and inner zone is crucial for understanding the radiation environment in this regime closest to Earth.","PeriodicalId":365284,"journal":{"name":"2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122051012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Bistatic Scattering Coefficients of a Tree Covered Mountainside at L Band L波段树木覆盖山腰的双基地散射系数

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552359

C. Suer, D. Breton, C. Haedrich, R. Lang

引用次数: 1

Two Whistler-Mode Waves Modulation By Background-Level Density Irregularity During The Recovery Phase of A Geomagnetic Storm 地磁风暴恢复阶段背景水平密度不规则对两个哨声模式波的调制

2021 USNC-URSI Radio Science Meeting (USCN-URSI RSM) Pub Date : 2021-08-09 DOI: 10.23919/USNC-URSIRSM52661.2021.9552349

Xu Liu, W. Gu, Z. Xia, Lunjin Chen, R. Horne

引用次数: 0