Vertical electric field - Vostok from 2006-2011

These data are collected under a collaborative arrangement between the Australian Antarctic Division (Principal Investigator: Gary Burns) and the Russian Antarctic Expeditions (Most-recent contact: Alexandr Frank-Kamenetsky, Institute of Arctic and Antarctic Studies, St Petersburg)In late December 2005 (call it from 2006) a new electric field mill (EFM)commenced operation at Vostok. This electric field mill is mounted on an all metal post ~3m above the snow surface. This EFM is different in operation and deployment from an earlier instrument that operated 1998-2002 and 2004 which was mounted on a 1.5m metal pole at deployment.Only 'unprocessed' data and a text file of in-field calibration data are included with this download. No selection has been made of 'fair-weather' data.Filenames of 'unprocessed' data are of the form VOSEF1-2006-002-0000.logVOSEF1 indicates that the data are of Vostok electric field data2006 indicates the year002 indicates the day of year0000 indicates that this is the first file for that day [If there has been continuous data collection, it will be the only file for the day. If the instrument has stopped and been restarted, this number is incremented]The file is written in ASCII format.A fileheader is included with each file, of the form:; EFM Log File; Date Opened Monday, 2 January 2006 00:00:00 ; ; 1 - DOY ; 2 - TimeStamp ; 3 - RPM ; 4 - Field ; 5 - Cal State ; 6 - Rotor Temperature ; DOY, timestamp, RPM, Field, Cal, Rotor Temp002,2006-01-02 00:00:00,1618,3958654,0,5.68'DOY' is Day-Of-Year'timestamp' is date and time, in Universal time.'RPM' is 'rotations per minute', the speed of rotation of the dipole. For most of the year this value is not correctly recorded.'Field' is just the raw digital value of the measurement 'Cal' there are two internal calibrations possible. A cal state of '1' indicates an internal 'zero level' check and a cal state of '2' indicates a fixed voltage offset (never fully calibrated). A '0' cal state indicates an atmospheric measurement was being made. From about 16th January 2006 on, no internal calibration have been activated. The cal state is always '0' indicating an atmospheric measurement is being made.'Rotor Temperature' is the temperature of the electronics in degrees C.Up until 16th January 2006 various tests and comparisons were being made with the instrument and while the 'unprocessed' data fro this early interval is provided, regular measurements commenced at this date.The 'Field' raw values are relative vertical geoelectric field measurements collected every 10 seconds. They are positive for a field directed downward.Each month the EFM is calibrated by placing a Faraday Box over the instrument. A separate calibration ASCII text file for each year [e.g. EFM_Cal_2006.txt] indicates the calibration results. These have not been applied to the data supplied. Care needs to be taken as difficulties with the calibration procedure (for example ice in one side of the calibration cables) have been known to occur. These issues are discussed, when noticed, in the calibration text file. Applying the calibration results to the raw data does not yield absolute values. They are determined relative to the 'calibration box', but as the compression associated with the instrumentation is unknown, data can only be regarded as relative not absolute measurements. As a rough estimate, dividing the 'field' value by 10,000 yields an value approximately equal to the 'volts per metre', positive downward, relative to the calibration box. Note: the instrument compression associated with the 'installed-in-2006' EFM is significantly different to the 1998-2004 Vostok EFM, principally but not exclusively due to the different heights of the mill.For the 'unprocessed' data supplied no selection for 'fair-weather' has been made. A method of selecting 'fair-weather' data for the 1998-2002 data is described in: Burns, G.B., Frank-Kamenetsky, A.V., Troshichev, O.A., Bering, E.A., Reddell, B.D. (2005) Interannual consistency of bi-monthly differences in diurnal variations of the ground-level, vertical electric field. Journal of Geophysical Research 110, D10106. doi:10.1029/2004JD005469. This method cannot be directly applied to the post-2006 data due to the different 'instrument compression'Gary Burns is working on a 'fair weather' selection of the Vostok post-2006 data, and a comparison with coincident vertical electric field measurements at Concordia.The ASAC_974 project formally concluded in June 2011, but the Russians (contact: Alexandr Frank-Kamenetsky, Institute of Arctic and Antarctic Studies, St Petersburg) have continued data collection at Vostok after this time, under an agreement to utilise the Australian developed equipment. Taken from the 2008-2009 Progress Report:Public summary of the season progress:Two papers showing a sun-weather association (ground pressure and clouds with solar wind) and linking the process to the atmospheric circuit have been published. These support a process via which solar variability influences weather via the atmospheric circuit.Vertical electric field data were collected at Vostok over 2008.An electric field mill was deployed at Dome C (Concordia) to help distinguish global and local influences on the atmospheric circuit.A web-site detailing the IPY SLAP [Solar Linkages to Atmospheric Processes] project has been maintained [http://www.ipy.org/index.php?/ipy/detail/solar_variability].World Wide Lightning Location Network VLF receivers operated at Davis (and Kingston) during 2008 [http://webflash.ess.washington.edu/]Taken from the 2009-2010 Progress Report:Public summary of the season progress:Global warming leads to enhanced atmospheric convection. Associated electrical activity (thunderstorms and electrified clouds) dominantly drives a globally-uniform atmospheric circuit linking the ionosphere to the surface. Four papers investigating atmospheric convection linkages to the ionosphere were published.Electric field data were collected at Vostok and Concordia on the Antarctic Plateau to measure the atmospheric circuit. The dominance of a global signal (atmospheric convection) in these measurements and an improved understanding of local contributions (solar wind and local meteorology) were obtained.A World Wide Lightning Location Network receiver was re-established at Davis. This contributes to a global lightning detection network [http://webflash.ess.washington.edu/]See also the metadata records with the IDs - ASAC_974_1 and ASAC_974_Concordia.

本数据集由澳大利亚南极局（Australian Antarctic Division，首席研究员：Gary Burns）与俄罗斯南极考察队（Russian Antarctic Expeditions，最新联系人：Alexandr Frank-Kamenetsky，圣彼得堡北极与南极研究所）合作采集。
2005年12月底（可记为2006年），沃斯托克站（Vostok）新安装的电场仪（electric field mill, EFM）正式投入运行。该电场仪安装在雪面上方约3米的全金属立柱上，其运行机制与部署方式均不同于1998-2002年及2004年使用的旧仪器：旧仪器部署于1.5米高的金属杆上。
本次下载仅包含未处理数据与一份现场校准数据文本文件，未对晴好天气数据（fair-weather data）进行任何筛选。
未处理数据的文件名格式为`VOSEF1-YYYY-DDD-XXXX.log`，各部分含义如下：
- `VOSEF1`：表示数据为沃斯托克站电场数据；
- `YYYY`：数据采集年份；
- `DDD`：年积日（Day-of-Year, DOY）；
- `XXXX`：当日首个数据文件编号。若持续采集，则当日仅存在一个该编号的文件；若仪器停机后重启，则该编号将递增。
数据文件采用ASCII格式存储，每个文件均包含文件头，示例格式如下：

; EFM Log File
; Date Opened Monday, 2 January 2006 00:00:00
; ; 1 - DOY ; 2 - TimeStamp ; 3 - RPM ; 4 - Field ; 5 - Cal State ; 6 - Rotor Temperature
; DOY, timestamp, RPM, Field, Cal, Rotor Temp
002,2006-01-02 00:00:00,1618,3958654,0,5.68

各字段含义如下：
- `DOY`：年积日；
- `timestamp`：世界时（Universal time）格式的日期与时间；
- `RPM`：每分钟转数（rotations per minute），即偶极子的旋转速度，一年中多数时段该值未被正确记录；
- `Field`：测量得到的原始数字值；
- `Cal`：内部校准状态，支持两种内部校准模式：校准状态为`1`表示内部零电平检测，`2`表示固定电压偏移（未完成完整校准），`0`表示正在进行大气测量。2006年1月16日起，未再启用内部校准，校准状态始终为`0`，即正在进行大气测量；
- `Rotor Temperature`：电子设备的温度，单位为摄氏度。
2006年1月16日前，该仪器进行了各类测试与对比实验，本下载包含该时段的未处理数据，但常规观测自该日期起正式启动。
`Field`字段为每10秒采集一次的相对垂直地电场测量值，场值为正时表示电场方向向下。
每月需将法拉第箱（Faraday Box）罩在仪器上，对电场仪进行校准。各年度均有单独的校准ASCII文本文件（如`EFM_Cal_2006.txt`），其中记录了校准结果，但未应用于本次提供的数据。需注意，校准流程曾出现过故障（如校准线缆一侧结冰），相关问题会在校准文本文件中记录说明。对原始数据应用校准结果后，仍无法得到绝对测量值（absolute values）：校准结果是相对于校准箱确定的，但仪器的增益系数未知，因此数据仅能视为相对测量值，而非绝对测量值。粗略估算可知，将`Field`值除以10000后，可得到相对于校准箱的、单位为伏特每米（volts per metre）的近似场值（正号表示电场向下）。需注意：2006年安装的电场仪的仪器增益与1998-2004年的沃斯托克电场仪存在显著差异，这主要（但非完全）源于仪器安装高度不同。
本次提供的未处理数据未进行晴好天气筛选。针对1998-2002年数据的晴好天气筛选方法已发表于：Burns, G.B., Frank-Kamenetsky, A.V., Troshichev, O.A., Bering, E.A., Reddell, B.D. (2005) 地面垂直电场日变化双月差异的年际一致性. 《地球物理学研究杂志》110, D10106. doi:10.1029/2004JD005469。由于仪器增益不同，该方法无法直接应用于2006年后的数据。Gary Burns正在对2006年后的沃斯托克站数据进行晴好天气筛选，并与康科迪亚站（Concordia）同步的垂直电场测量数据进行对比。
ASAC_974项目已于2011年6月正式结题，但俄罗斯团队（联系人：Alexandr Frank-Kamenetsky，圣彼得堡北极与南极研究所）依据使用澳大利亚研发设备的协议，在项目结题后仍持续在沃斯托克站进行数据采集。
以下为2008-2009年度进展报告节选：
> 本季度进展公开总结：
> 已有两篇论文揭示了太阳活动与天气（地面气压、云量与太阳风）的关联，并将该关联机制与大气电路相联系，这些研究支持了太阳活动通过大气电路影响天气的过程。
> 2008年，沃斯托克站采集了垂直电场数据。
> 康科迪亚站（Dome C）部署了电场仪，以帮助区分大气电路的全球与局地影响因素。
> 已维护一个用于介绍国际极地年-太阳活动与大气过程关联（IPY SLAP, Solar Linkages to Atmospheric Processes）项目的网站[http://www.ipy.org/index.php?/ipy/detail/solar_variability]。
> 2008年，戴维斯站（Davis）及金斯顿站（Kingston）部署了全球闪电定位网络（World Wide Lightning Location Network, WWLLN）的甚低频接收机（VLF receivers）[http://webflash.ess.washington.edu/]。
以下为2009-2010年度进展报告节选：
> 本季度进展公开总结：
> 全球变暖导致大气对流增强，相关的电活动（雷暴与带电云）是连接电离层与地表的全球均匀大气电路的主要驱动因素。已有四篇论文探讨了大气对流与电离层的关联机制。
> 南极高原的沃斯托克站与康科迪亚站均采集了电场数据，以用于大气电路研究。研究明确了全球信号（大气对流）在观测中的主导地位，并加深了对太阳风、局地气象等局地贡献因素的理解。
> 戴维斯站重新部署了全球闪电定位网络接收机，该设备为全球闪电探测网络提供支持[http://webflash.ess.washington.edu/]。
相关元数据记录的ID为`ASAC_974_1`与`ASAC_974_Concordia`。