BARREL 4F Ephemeris (EPHM) Geographic and Magnetic Coordinates, Level 2, 4 s Data

Geographic and Magnetic Coordinates: The ephemeris data products, which include the balloon epoch time, latitude, longitude, and altitude, are each returned from the payload once every 4s. Geographic coordinates are obtained from an onboard Global Positioning System, GPS, unit. Magnetic coordinates are derived by using the International Radiation Belt Environment Modeling, IRBEM, FORTRAN library.

The BARREL Mission was a multiple-balloon investigation designed to study electron losses from Earth's Radiation Belts. Selected as a NASA Living with a Star Mission of Opportunity, BARREL was designed to augment the Radiation Belt Storm Probes, RBSP, mission by providing measurements of the spatial and temporal variations of electron precipitation from the radiation belts. The RBSP mission has since been renamed the Van Allen Probes mission. Each BARREL balloon carried an X-ray spectrometer to measure the bremsstrahlung X-rays produced by precipitating relativistic electrons as they collide with neutrals in the atmosphere, and a DC magnetometer to measure ULF-timescale variations of the magnetic field. BARREL observations collected near latitudes close to either the antarctic and arctic circles at stratospheric altitudes at about 30 km. The BARREL instrumentation provided the first balloon measurements of relativistic electron precipitation while comprehensive in situ measurements of both plasma waves and energetic particles were available. Also, the BARREL data has been used to characterize the spatial scale of precipitation at relativistic energies.

The initial pair of balloon campaigns that were conducted initially during the Austral summer months of January and February of 2013 and 2014 with launches from two stations located in Antarctica: the British base located at Halley Bay on the Brunt Ice Shelf and the South African SANAE IV base (SANAE stand for South African National Antarctic Expedition) located in Vesleskarvet, Queen Maud Land. For the 2013 and 2014 the balloon campaigns, the launch plan was designed to maintain an array with about five payloads spread across about six hours of magnetic local time, MLT, in the region that magnetically maps to the radiation belts. Thus, the BARREL balloon constellation constituted an evolving and slowly moving array able to study relativistic electron precipitation from the radiation belts.

Later campaigns were undertaken in 2015 and 2016 from the Esrange Space Center located in Kiruna, Sweden. The 2015 and 2016 campaigns were undertaken in coordination with the Van Allen Probes mission, the European Incoherent Scatter Scientific Association, EISCAT, incoherent scatter radar system, and other ground and space based instruments. Seven balloon launches occurred during the August 2015 BARREL campaign. A total of eight flights occurred during August 2016.

Summing over the four BARREL campaigns, over 50 small, approximately 20 kg, stratospheric balloons were successively launched. The website creeated and hosted by A.J. Halford (see Information URL below) reports that: "By the end of the campaigns, there were over 90 researchers coordinating on a daily basis with the BARREL team working on 7 different satellite missions, 1 other balloon mission, and way too many ground based instruments to count." Although the BARREL mission launched only balloons during the years from 2013 to 2016, research using data collected on these flights is ongoing, so stay tuned for updates! All data and analysis software are freely available to the scientific community.

The information listed above in this resource description was compiled by referencing several BARREL related resources including primarily the Millan et al. (2013) Space Science Reviews publication, the BARREL at Dartmouth mission web site, and the website maintained by A.J. Halford.

The current release of all BARREL CDF data products are Version 10 files.

BARREL will make all its scientific data products quickly and publicly available but all users are expected to read and follow the BARREL Data Usage Policy listed below.

BARREL Data Usage Policy

BARREL data products are made freely available to the public and every effort is made to ensure that these products are of the highest quality. However, there may occasionally be issues with either the instruments or data processing that affect the accuracy of data. When possible, a quality flag is included in higher level data products, and known issues are posted in the BARREL data repository. You are also strongly encouraged to follow the guidelines below if you are planning a publication or presentation in which BARREL data are used. This will help you ensure that your science results are valid.

* Users should always use the highest version numbers of data and analysis tools. Browse/quick-look plots are not intended for science analysis or publication and should not be used for those purposes without consent of the principal investigator, PI.
* Users should notify the BARREL PI of the data use and investigation objectives. This will ensure that you are using the data appropriately and have the most recent version of the data or analysis routines. Additionally, if a BARREL team member is already working on a similar or related topic, they may be able to contribute intellectually.
* If BARREL team members are not part of the author list, then users should Credit/Acknowledge the BARREL team as follows: We acknowledge the BARREL team (PI: Robyn Millan) for use of BARREL data.
* Users are also requested to provide the PI with a copy of each manuscript that uses BARREL data upon submission of that manuscript for consideration of publication. On publication, the citation should be transmitted to the PI.

The BARREL PI can be contacted at: [e-mail].

An online copy of the BARREL Data Usage Policy document can be found at: https://barrel.rmillan.host.dartmouth.edu/documents/data.use.policy.pdf.

地理与磁坐标：包含气球历元时间、纬度、经度与海拔高度的星历数据产品，由有效载荷每4秒返回一次。地理坐标由机载全球定位系统（Global Positioning System, GPS）获取，磁坐标则通过国际辐射带环境模型（International Radiation Belt Environment Modeling, IRBEM）的FORTRAN库计算得到。

BARREL任务是一项多气球探测计划，旨在研究地球辐射带的电子逃逸现象。该任务被选为美国国家航空航天局（NASA）“恒星伴生机遇任务（Living with a Star Mission of Opportunity）”项目，通过测量辐射带电子沉降的时空变化，对辐射带风暴探测器（Radiation Belt Storm Probes, RBSP）任务进行补充。RBSP任务后续更名为范艾伦探测器（Van Allen Probes）任务。每台BARREL气球搭载一台X射线光谱仪，用于测量相对论性电子在大气层中与中性粒子碰撞时产生的轫致辐射X射线；同时搭载一台直流磁强计，用于测量超低频（ULF）时标的磁场变化。BARREL观测站点位于接近南极圈与北极圈的纬度区域，飞行高度约30千米的平流层。BARREL探测仪器首次实现了相对论电子沉降的气球原位测量，同时可同步获取等离子体波与高能粒子的全面原位观测数据。此外，BARREL数据还被用于表征相对论能量下电子沉降的空间尺度。

首批气球观测任务分别于2013年和2014年的南半球夏季（1月至2月）开展，发射场地位于南极洲的两个站点：布伦特冰架（Brunt Ice Shelf）哈利湾（Halley Bay）的英国科考站，以及毛德皇后地（Queen Maud Land）维斯莱斯科维特（Vesleskarvet）的南非SANAE IV站（SANAE为南非国家南极考察队（South African National Antarctic Expedition）的缩写）。在2013与2014年的气球观测任务中，发射计划旨在维持一个由约5台有效载荷组成的阵列，这些载荷分布在磁地方时（magnetic local time, MLT）约6小时的范围内，覆盖磁场映射至辐射带的区域。由此，BARREL气球星座构成了一个动态且缓慢移动的探测阵列，可用于研究辐射带的相对论电子沉降现象。

后续的观测任务批次分别于2015年和2016年在瑞典基律纳的埃斯兰厄航天中心（Esrange Space Center）开展。2015与2016年的任务与范艾伦探测器任务、欧洲非相干散射科学协会（European Incoherent Scatter Scientific Association, EISCAT）非相干散射雷达系统，以及其他地面与空间探测仪器协同进行。2015年8月的BARREL任务共实施了7次气球发射，2016年8月的任务则完成了总计8次飞行。

综合四次BARREL观测任务，总计成功发射了超过50台重量约20千克的平流层小型气球。由A.J.哈尔福德创建并维护的网站（详见下文信息链接）曾报道：“任务结束时，已有超过90名研究人员每日与BARREL团队协同工作，参与7项不同的卫星任务、1项其他气球任务，以及数量难以统计的地面探测仪器的相关研究。”尽管BARREL任务在2013至2016年仅开展气球发射工作，但基于这些飞行任务采集数据的相关研究仍在持续，请敬请关注后续更新！所有数据与分析软件均对科学界免费开放。

本资源描述中列出的上述信息，参考了多项与BARREL相关的资料，主要包括Millan等人于2013年发表在《空间科学评论（Space Science Reviews）》的论文、达特茅斯学院BARREL任务官网，以及A.J.哈尔福德维护的网站。

当前发布的所有BARREL CDF数据产品均为版本10文件。

BARREL将快速公开所有科学数据产品，但所有使用者均需阅读并遵守下文列出的BARREL数据使用政策。

BARREL数据使用政策
BARREL数据产品对公众免费开放，团队将尽一切努力确保此类产品具备最高质量。但仪器或数据处理过程中偶尔可能出现影响数据准确性的问题。在可行的情况下，高阶数据产品会包含质量标记，已知问题会发布在BARREL数据仓库中。若您计划使用BARREL数据进行论文发表或学术汇报，我们强烈建议您遵循以下指南，以确保您的科研结果真实有效。

1. 使用者应始终使用数据与分析工具的最高版本。浏览图/快速预览图并非为科研分析或发表而设计，未经首席研究员（Principal Investigator, PI）许可，不得将其用于此类用途。
2. 使用者应将数据使用用途与研究目标告知BARREL任务首席研究员。此举可确保您正确使用数据，并获取最新版本的数据或分析程序。此外，若BARREL团队成员已在开展类似或相关主题的研究，他们或可为您提供学术上的帮助。
3. 若BARREL团队成员未列入作者名单，则使用者应按如下方式致谢BARREL团队：“我们感谢BARREL团队（首席研究员：Robyn Millan）提供的BARREL数据。”
4. 使用者还需在将使用BARREL数据的手稿提交发表审核时，向首席研究员提供手稿副本。论文正式发表后，需将引用信息告知首席研究员。

可通过以下邮箱联系BARREL任务首席研究员：[e-mail]。

BARREL数据使用政策文档的在线副本可通过以下链接获取：https://barrel.rmillan.host.dartmouth.edu/documents/data.use.policy.pdf。