Swarm-EMIC Research Project - EMIC database

This dataset comprises databases of electromagnetic ion cyclotron (EMIC) wave events detected by automated Pc1 wave finding algorithms developed by the VI3DLabs & University of Alberta team using Swarm 50 Hz magnetic field, 16 Hz electric field and 2 Hz Langmuir probe density datasets, as well as incorporating Canadian Space Agency CARISMA and NASA Van Allen Probes datasets. This dataset is published as a deliverable of the European Space Agency Swarm-EMIC project which aims to use Swarm datasets to investigate the impact of EMIC waves on energetic electron precipitation. A link to the project description can be accessed here: ttps://eo4society.esa.int/projects/swarm-emic/ The dataset is in CSV format with 2 possible formats for the EMIC wave confidence metric. The old format is a confidence score from 1-6, the new metric is a confidence matrix flagging specific conditions (e.g. Pc1 transverse wave energy; E/B fields corresponding to travelling Alfven wave; conjugate EMIC wave observations by CARISMA etc). The reason for the new format is to be able to flag multiple conditions simultaneously. If the file is a N x 25 or a N x 29 matrix, the EMIC wave flag is a confidence score; if it is a N x 31 or a N x 35 matrix, the EMIC wave flag is a confidence matrix. The confidence matrix files also have 'EB' in their filenames. The column values are defined below. tsBegin - EMIC event beginning (timestamp in datenum format)tsEnd - EMIC event ending (timestamp in datenum format)duration - EMIC event duration in secondsfCtr - event centre frequency in HzfBW - event bandwidth (full-width half maximum, or FWHM) in Hzellip - ellipticity (-1 for left-hand circular polarised, 0 for linear, +1 for right-hand circular polarised)minP2P - minimum peak-to-peak magnitude of the event (nT)medianP2P - median peak-to-peak magnitude of the event (nT)maxP2P - maximum peak-to-peak magnitude of the event (nT)BminCtr - the B-field minimum of the field line at the event centre (traced to the equator using IGRF)EMICband - EMIC band based on observed frequency and the traced estimated equatorial gyrofrequencies from BminCtr. Values are as follows: 0 = above H+ gyro, 1 = below H+ gyro, 2 = below He+ gyro, 3 = below O+ gyro, -1 = tracing failed/unknown bandMLTbegin - MLT at the beginning of the eventMLTctr - MLT at the centre of the eventMLTend - MLT at the end of the eventLmBegin - the McIlwain L-shell at the beginning of the eventLmCtr - Lm at centre of the eventLmEnd - Lm at end of the eventLstarBegin - L* at beginning of eventLstarCtr - L* at centre of the eventLstarEnd - L* at end of the eventgeoLatBegin - geographic latitude (in deg) at event beginninggeoLatEnd - geographic latitude (in deg) at event endgeoLonBegin - geographic longitude (in deg) at event beginninggeoLonEnd - geographic longitude (in deg) at event endcgmLatBegin - corrected geomagnetic (CGM) latitude (in deg) at beginning of event - only present in N x 29 and N x 35 data filescgmLatEnd - CGM latitude (in deg) at end of the event - only present in N x 29 and N x 35 data filescgmLonBegin - CGM longitude (in deg) at beginning of the event - only present in N x 29 and N x 35 data filescgmLonEnd - CGM longitude (in deg) at end of the event - only present in N x 29 and N x 35 data filesEMICconf - EMIC event confidence level - either a scalar confidence score or a N x 7 confidence matrix The EMIC event confidence level ('EMICconf') is defined on a 1-6 scale as follows: 1 - compressional Pc1 energy bounded from above and below by area of reduced power2 - transverse Pc1 energy bounded from above and below by area of reduced power3 - both compressional AND transverse Pc1 energy bounded from above and below by area of reduced power4 - as 3 but the centre frequency, lower and upper bounds (determined separately from half-maximum, i.e. 3dB either side of the peak) are within 0.5 Hz of each other5 - Pc1 event of at least level 2 is also conjugate with CARISMA ICM (100 Hz) ground magnetometers. Swarm and CARISMA FWHMs must overlap6 - Pc1 event of at least level 2 is also conjugate with Van Allen Probe satellite observations using EMFISIS fluxgate magnetometer (64 Hz). Swarm and VAP FWHMs must overlap Where the EMIC wave flag is a confidence matrix, the elements of the matrix are defined by the last N x 7 elements within the file. Each of the 7 elements corresponds to specific conditions; multiple conditions may be true simultaneously. The 7 conditions are as follows: 1st element - Pc1 energy in compressional mode2nd element - Pc1 energy in transverse mode3rd element - Pc1 energy in compressional and transverse mode matched within 0.5 Hz4th element - free-travelling Alfven wave confirmed with E- and B-fields5th element - Pc1 transverse-mode energy on Swarm AND conjugate CARISMA groundstation6th element - Pc1 transverse-mode energy on Swarm AND conjugate VAP-A B-field. The values here can be : 0 (no conjunction), 1 (Swarm-VAP conjunction), 2 (Swarm-VAP conjunction; Pc1 waves detected in both), or 3 (Swarm-VAP conjunction; Pc1 waves detected in both with matching frequencies/overlapping FWHM)7th element - Pc1 transverse-mode energy on Swarm AND conjugate VAP-B B-field. The values here can be : 0 (no conjunction), 1 (Swarm-VAP conjunction), 2 (Swarm-VAP conjunction; Pc1 waves detected in both), or 3 (Swarm-VAP conjunction; Pc1 waves detected in both with matching frequencies/overlapping FWHM) This database will be expanded in subsequent releases with new data from the 3 Swarm spacecraft. Any changes to the processing algorithms and format will be reflected in the new version Description file. The ZIP file ('SwarmEMICscripts.zip') contains the Matlab and Python codes which were used to generate the database. The code utilises the IRBEM field tracing library: https://prbem.github.io/IRBEM/ as well as the aacgmv2 Python package (https://github.com/aburrell/aacgmv2). For any questions, please reach out to Dr Ivan Pakhotin ([e-mail]) or Prof Ian R Mann ([e-mail]).本数据集包含由VI3DLabs与阿尔伯塔大学团队开发的自动化Pc1波探测算法所识别的电磁离子回旋波（electromagnetic ion cyclotron, EMIC）事件数据库，所用数据源包括Swarm卫星的50 Hz磁场、16 Hz电场以及2 Hz朗缪尔探针（Langmuir probe）密度数据集，同时整合了加拿大航天局CARISMA与美国国家航空航天局（NASA）范艾伦探测器（Van Allen Probes）的数据集。 本数据集作为欧洲空间局（ESA）Swarm-EMIC项目的交付成果发布，该项目旨在利用Swarm卫星数据集探究EMIC波对高能电子沉降的影响。项目描述的访问链接为：https://eo4society.esa.int/projects/swarm-emic/。 本数据集采用CSV格式，其EMIC波置信度指标存在两种格式：旧格式为1至6的置信分数，新格式为置信矩阵，用于标记特定条件（例如Pc1横向波能量、对应行波阿尔文波（Alfvén wave）的电场/磁场、CARISMA的共轭EMIC波观测等）。采用新格式的目的是实现多条件同时标记。 若文件为N×25或N×29矩阵，则EMIC波标记为置信分数；若为N×31或N×35矩阵，则EMIC波标记为置信矩阵。置信矩阵文件的文件名中包含"EB"字段。各列字段的定义如下： tsBegin：EMIC事件起始时间（datenum格式的时间戳） tsEnd：EMIC事件结束时间（datenum格式的时间戳） duration：EMIC事件持续时长，单位为秒 fCtr：事件中心频率，单位为Hz fBW：事件带宽（半高全宽，full-width half maximum, FWHM），单位为Hz ellip：偏振椭圆率（-1表示左旋圆偏振，0表示线偏振，+1表示右旋圆偏振） minP2P：事件的最小峰峰值幅度，单位为nT medianP2P：事件的峰峰值幅度中位数，单位为nT maxP2P：事件的最大峰峰值幅度，单位为nT BminCtr：事件中心处磁力线的最小磁场强度（通过国际地磁参考场（International Geomagnetic Reference Field, IGRF）追踪至赤道得到） EMICband：基于观测频率与由BminCtr追踪得到的赤道回旋频率估算值划分的EMIC频带，取值规则如下：0 = 高于H+回旋频率，1 = 低于H+回旋频率，2 = 低于He+回旋频率，3 = 低于O+回旋频率，-1 = 追踪失败/未知频带 MLTbegin：事件起始时刻的磁地方时（magnetic local time, MLT） MLTctr：事件中心时刻的磁地方时 MLTend：事件结束时刻的磁地方时 LmBegin：事件起始时刻的麦克尔万L壳（McIlwain L-shell）参数Lm LmCtr：事件中心时刻的Lm参数 LmEnd：事件结束时刻的Lm参数 LstarBegin：事件起始时刻的L*参数 LstarCtr：事件中心时刻的L*参数 LstarEnd：事件结束时刻的L*参数 geoLatBegin：事件起始时刻的地理纬度，单位为度 geoLatEnd：事件结束时刻的地理纬度 geoLonBegin：事件起始时刻的地理经度，单位为度 geoLonEnd：事件结束时刻的地理经度 cgmLatBegin：事件起始时刻的修正地磁坐标（corrected geomagnetic, CGM）纬度，单位为度，仅在N×29与N×35格式的数据文件中存在 cgmLatEnd：事件结束时刻的CGM纬度，单位为度，仅在N×29与N×35格式的数据文件中存在 cgmLonBegin：事件起始时刻的CGM经度，单位为度，仅在N×29与N×35格式的数据文件中存在 cgmLonEnd：事件结束时刻的CGM经度，单位为度，仅在N×29与N×35格式的数据文件中存在 EMICconf：EMIC事件置信度等级，可为标量置信分数或N×7维置信矩阵 EMIC事件置信度（EMICconf）采用1至6的分级标准，具体定义如下： 1级：压缩模式Pc1波能量的上下边界均处于功率下降区域内 2级：横向模式Pc1波能量的上下边界均处于功率下降区域内 3级：压缩模式与横向模式的Pc1波能量上下边界均处于功率下降区域内 4级：满足3级标准，且事件中心频率、上下边界（通过半高全宽，即峰值两侧各3dB处确定）的差值均不超过0.5 Hz 5级：至少达到2级标准的Pc1事件，同时与CARISMA ICM（100 Hz）地面磁力仪的观测形成共轭。Swarm卫星与CARISMA的FWHM必须存在重叠 6级：至少达到2级标准的Pc1事件，同时与使用EMFISIS磁通门磁力仪（64 Hz）的范艾伦探测器卫星观测形成共轭。Swarm卫星与范艾伦探测器（Van Allen Probes, VAP）的FWHM必须存在重叠 当EMIC波标记为置信矩阵时，矩阵的7个元素对应文件末尾的N×7个字段，每个元素代表一项特定条件，且可同时满足多项条件。7项条件具体如下： 第1元素：压缩模式下的Pc1波能量 第2元素：横向模式下的Pc1波能量 第3元素：压缩与横向模式的Pc1波能量匹配度差值不超过0.5 Hz 第4元素：通过电场与磁场验证的自由行阿尔文波 第5元素：Swarm卫星观测到的Pc1横向模式波，且与CARISMA地面站形成共轭观测 第6元素：Swarm卫星观测到的Pc1横向模式波，且与范艾伦探测器A星（VAP-A）的磁场数据形成共轭观测。该元素的取值可为：0（无共轭）、1（Swarm与VAP-A形成共轭）、2（Swarm与VAP-A形成共轭且双方均探测到Pc1波）、3（Swarm与VAP-A形成共轭且双方均探测到Pc1波，且频率匹配/FWHM存在重叠） 第7元素：Swarm卫星观测到的Pc1横向模式波，且与范艾伦探测器B星（VAP-B）的磁场数据形成共轭观测。该元素的取值可为：0（无共轭）、1（Swarm与VAP-B形成共轭）、2（Swarm与VAP-B形成共轭且双方均探测到Pc1波）、3（Swarm与VAP-B形成共轭且双方均探测到Pc1波，且频率匹配/FWHM存在重叠） 本数据库后续版本将纳入3颗Swarm卫星的新数据进行扩充。处理算法与格式的任何更新均会在新版本的说明文件中体现。 压缩包"SwarmEMICscripts.zip"包含用于生成本数据库的Matlab与Python代码，该代码使用了IRBEM场追踪库（https://prbem.github.io/IRBEM/）以及aacgmv2 Python包（https://github.com/aburrell/aacgmv2）。 如有任何疑问，请联系伊万·帕霍京博士（[e-mail]）或伊恩·R·曼教授（[e-mail]）。