Electromagnetic induction measurements with the vertically oriented dipole of the CMD Mini Explorer (71 cm transmitter-receiver spacing) taken in June 2023 in the Lower Havel Inner Delta near Lake Gülpe, Brandenburg (Germany)

Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2023. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2023 is located to the north and northeast of the Gülpe research station. It has a total area of 12.3 ha. The reference line was located in the southern part of the study area. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed.The data set contains the EMI data with an intercoil spacing of 0.71 m.2023年6月，我们使用捷克布尔诺GF仪器有限公司（GF Instruments s.r.o., Brno, Czech Republic）生产的CMD-Mini Explorer型仪器开展电磁感应（EMI）测量。本次测量采用线圈间距分别为0.32 m（记为VDP1）、0.71 m（记为VDP2）及1.18 m（记为VDP3）的垂直偶极子（VDP）模式，其有效探测深度分别为0.5 m（VDP1）、1.0 m（VDP2）及1.8 m（VDP3）。据仪器厂商披露，70%的采集信号来源于上述有效探测深度以上的区域。该EMI传感器可测量视电导率（ECa，单位为mS/m）。测量时，我们手持仪器保持其距地面约0.2 m的高度，并通过差分全球定位系统（D-GPS，徕卡GPS1200）直接连接以获取定位信息。数据采集速率为每秒5次测量。数据质量通过在每次测量前后均采集一条参考线数据进行校验。2023年6月通过EMI调查的区域位于Gülpe研究站的北侧及东北侧，总面积为12.3公顷。参考线设置在研究区的南部区域。由于数据质量良好，无需进行漂移校正。本数据集已剔除参考线数据及单个异常值，包含线圈间距为0.71 m的EMI测量数据。