Absolute vertical electric field data raw and selected data - Concordia from 2006-2011; processed 1-minute averages

The vertical electric field data were collected using an electric field mill (EFM) developed and deployed under the approval of AAS_974 (Principal Investigator: Gary Burns). The Concordia EFM deployment and data collection was approved by IPEV (France)/PNRA(Italy) via 'Electrocite Atmospherique DC 33N'. 1-minute absolute vertical electric field averages (positive down; derived from 10 sec resolution data available at AAS_974_Concordia) for raw (=all available 1-min averages) and selected nvr, mvr and svr data which are described, tested and discussed in Burns et al. (2017). The values here-in have not been corrected for the solar-wind-imposed-potential (SWIP)-above-the-station. SWIP correction values are only derived for 20-minute averages and are applied to the nvr, mvr and svr 20-min averages (AAS_974_Concordia_2009to2011_20min) and described in Burns et al. (2017).In January 2009 an electric field mill (EFM) was deployed at Concordia and operated until December 2011. This electric field mill is mounted on an all metal post ~3m above the snow surface. We use all metal coverings on our instrumentation as near-by insulators can retain a charge which could be slowly released and influence the electric field measurements over significant intervals. Values are positive for a downward-directed electric field. This EFM is similar to one deployed at Vostok in January 2006. The Concordia EFM 'compression factor' is taken to be equivalent to the similar instrument calibrated at Vostok and was determined by stepping voltages between +5 and -5kV through a wire above the EFM at Vostok. Linkage to the Concordia EFM was determined using a Faraday-shielded box containing parallel plates placed over the rotating dipole to which a range of stepped voltages were applied. A single calibration factor has been applied for the entire (2009-2011) Concordia data set and absolute values (V/m) at ~3m above the snow surface are provided. The three separate data selections are as described in Burns et al. (2017). An initial rejection of the minute-averaged data is made for electric fields with two hour prior to and after exceeding 333 V/m for all three data selections. This rejects measurements generally influenced by local falling, wind-blown or lifted snow or ice which result in high electric field values. The extended time intervals are a conservative allowance for the local influences prior to the cut-off electric field value being reached and after lower values are again recorded. For two of the three selected data sets an additional criteria with different levels of severity was used to reject rapid variations below the cut-off threshold based on jumps in the electric field within a five-minute interval. Due to the time constant (~15 minutes) associated with the atmospheric circuit, rapid variations in the electric field are more likely to be associated with local influences. This is confirmed in Burns et al. (2017) by the relative association of the selected data sets with the SWIP-above-Concordia and independently by comparison with simultaneous electric field measurements at Vostok. Strong variation rejection (svr) data selections additionally reject minute-averaged data within 30 minutes of a jump of 33 V/m (with 5 minutes). Medium variation rejection (mvr) data selections additionally reject minute-averaged data within 10 minutes of a jump of 57 V/m (within 5 minutes). No variation rejection (nvr) data selections made no rejection on the basis of rapid variations (within 5 minutes). The fourth electric field data set listed herein is all the raw 1-minute averages. This includes the high values (which are constrained by the electronics to an extreme upper value). Earlier in the deployment, this may include 1-min averages associated with instrument calibrations. The raw 10-sec data associated with these calibrations were used to match the Concordia instrument to the similar Vostok instrument to determine absolute values. The 1 minute averages should not be used for calibration purposes as the 1-min averages may include transition intervals. Tests and changes of instrumentation resulted in the earliest selected (nvr) 1-minute-averaged electric field measurements at Concordia commencing at 0710UT, 9th January, 2009. Raw 1-minute-averaged values are intermittent from 0744UT 5th January, 2009.The data provided consists of up to 12 fields. The first eight columns are date-time related fields. The first field is an Excel derived date-time to the mid-point of the 1-minute average. The second field is the 'year', followed by the 'day-of-year', 'month', 'day-of-month', 'UT-hour', UT-min' and 'UT-second' of the averaged data. The ninth column is the raw minute-averaged absolute value (V/m downward) of the measured vertical electric field. The tenth to twelfth columns list the nvr, mvr and svr Concordia 1-minute electric field averages, without SWIP corrections, but otherwise as described and tested in Burns et al. (2017). Missing data are presented as blanks. Suggested acknowledgements for the utilization of these data are: 'The Concordia electric field data were collected by collaboration between AAD (Australia), IPEV (France) and PNRA (Italy). Australian involvement was approved by the Australian Antarctic Advisory Committee (AAS 974). Deployment and data collection at Concordia was approved by IPEV/PNRA via 'Electricite Atmospherique DC 33N'. Concordia meteorological data were provided by IPEV/PNRA project 'Routine Meteorological Observations at Station Concordia,' which is financially supported by ENEA (Italy).' References: Burns, G.B., A.V. Frank-Kamenetsky, B.A. Tinsley, W.J.R. French, and P. Grigioni, G. Camporeale, and E.A. Bering, 2017: Atmospheric global circuit variations from Vostok and Concordia electric field measurements. J. Atmos. Sci., 74, 783-800, doi:10.1175/JAS-D-16-0159-1.

本数据集的垂直电场数据由电场仪（electric field mill, EFM）采集，该仪器的研发与部署经AAS_974项目批准（项目负责人：Gary Burns）。

康科迪亚站电场仪的部署与数据采集工作经法国极地研究所（IPEV）/意大利国家南极研究计划（PNRA）以“Electrocite Atmospherique DC 33N”项目批准。

所有1分钟垂直电场绝对平均值以向下为正方向，其计算基于AAS_974_Concordia公开的10秒分辨率原始数据，涵盖原始数据集（即全部可用的1分钟平均数据）以及经筛选的无变化剔除（no variation rejection, nvr）、中等变化剔除（medium variation rejection, mvr）与强变化剔除（strong variation rejection, svr）数据，上述三类筛选数据的细节、测试与讨论参见Burns等人（2017）的研究。

本次发布的电场数值未修正站址上方太阳风诱导电势（solar-wind-imposed-potential, SWIP）。SWIP修正值仅针对20分钟平均数据计算得到，且已应用于AAS_974_Concordia_2009to2011_20min数据集的nvr、mvr与svr类20分钟平均数据，相关细节参见Burns等人（2017）的研究。

2009年1月，康科迪亚站部署了一台电场仪，并持续运行至2011年12月。该电场仪安装在距雪面约3米的全金属立柱上。仪器全部采用金属外壳，因为附近的绝缘材料会积累电荷并缓慢释放，进而在较长时间段内干扰电场测量结果。

电场数值以向下方向为正。该电场仪与2006年1月在沃斯托克（Vostok）站部署的同类仪器规格一致。康科迪亚站电场仪的“压缩因子”与沃斯托克站经标定的同类仪器等效，其标定过程为：在沃斯托克站电场仪上方的导线施加+5kV至-5kV的步进电压，以此确定压缩因子。

康科迪亚站电场仪的标定关联通过法拉第屏蔽箱完成：该箱内置平行极板，将其置于旋转偶极子上方并施加一系列步进电压。本次2009-2011年康科迪亚站的全部数据集采用统一的标定因子，最终提供的电场绝对数值对应雪面上方约3米处的场强，单位为V/m。

三类筛选数据的具体规则参见Burns等人（2017）的研究。针对三类筛选数据集，首先会剔除超出333 V/m阈值前后各2小时内的1分钟平均数据，以此排除受局地降雪、风吹积雪或浮冰影响导致的高电场值测量结果。阈值前后的宽时间段设置是为了保守地覆盖阈值达到前后的局地干扰时段。

在三类筛选数据集中，有两类额外采用了不同严苛程度的标准，基于5分钟内的电场跳变情况剔除阈值以下的快速变化数据。由于大气电路的时间常数约为15分钟，电场的快速变化更可能与局地干扰相关。这一结论在Burns等人（2017）的研究中得到验证：一是筛选数据集与康科迪亚站上方SWIP的相对关联性，二是通过与沃斯托克站的同步电场测量结果进行独立对比。

强变化剔除（svr）数据集会额外剔除5分钟内出现33 V/m跳变前后30分钟内的1分钟平均数据；中等变化剔除（mvr）数据集则额外剔除5分钟内出现57 V/m跳变前后10分钟内的1分钟平均数据；无变化剔除（nvr）数据集未针对5分钟内的快速变化进行任何剔除操作。

本次发布的第四类电场数据集为全部原始1分钟平均数据，其中包含受仪器电子学上限限制的高值数据。在部署初期，该数据集可能包含与仪器标定相关的1分钟平均数据——此类标定对应的10秒分辨率原始数据曾用于匹配康科迪亚站与沃斯托克站的同类仪器，以确定电场绝对数值。由于1分钟平均数据可能包含过渡时段的观测值，因此不可用于仪器标定工作。

经过仪器测试与调整后，康科迪亚站最早的筛选类（nvr）1分钟平均电场观测数据始于2009年1月9日07:10UT。原始1分钟平均数据的观测时段则从2009年1月5日07:44UT开始，但存在间断。

本次提供的数据最多包含12列字段。前8列为日期时间相关字段：第一列为Excel格式的时间戳，对应1分钟平均时段的中点；第二列为年份，后续依次为年积日、月份、当月日期、UT时、UT分与UT秒。第9列为实测垂直电场的原始1分钟平均绝对数值（单位为V/m，向下为正）。第10至12列分别为未经过SWIP修正的康科迪亚站nvr、mvr与svr类1分钟平均电场数据，其筛选规则与测试细节参见Burns等人（2017）的研究。缺失数据以空白单元格表示。

使用本数据集时的致谢参考模板如下：「康科迪亚站电场数据由澳大利亚南极局（AAD）、法国极地研究所（IPEV）与意大利国家南极研究计划（PNRA）合作采集。澳大利亚方面的参与经澳大利亚南极咨询委员会批准（项目编号AAS 974）。康科迪亚站的仪器部署与数据采集工作经IPEV/PNRA以「Electrocite Atmospherique DC 33N」项目批准。康科迪亚站气象数据由IPEV/PNRA项目「Routine Meteorological Observations at Station Concordia」提供，该项目由意大利国家新技术、能源与可持续经济发展委员会（ENEA）资助。」

参考文献：Burns, G.B., A.V. Frank-Kamenetsky, B.A. Tinsley, W.J.R. French, P. Grigioni, G. Camporeale 与 E.A. Bering, 2017：基于沃斯托克站与康科迪亚站电场测量结果的全球大气电路变化. 《大气科学杂志》（Journal of the Atmospheric Sciences）, 74, 783-800, doi:10.1175/JAS-D-16-0159-1.