Four-year measurements from Sierra Nevada ELF station. Years 2013, 2017

This folder contains subfolders for the years 2013 (from March, inclusive) and 2017 (January and February) with time domain raw data from the Sierra Nevada ELF station. Each year contains folders for each month, named with the four digits corresponding to year and month, e.g., 1412 stands for the raw data during December 2014. Within each month folder, the data and information files for each sensor and each hour are available. Data are stored in files containing measurements corresponding to a time period of approximately one hour. The filenames begin with a common part, “smplGRTU1_sensor_”, followed by a specific part to denote the sensor used (0 for the NS orientation and 1 for the EW orientation), the date and the initial time of the measurement recorded. For example, smplGRTU1_sensor_0_1412010430, stands for data measured by the NS-oriented magnetometer, in the year 2014, month 12, day 01, hour 04, and starting minute, 30. The information file has the same name but ends with _info.txt. Since the initial time is not fixed, the filenames in each folder are not completely determined. For this reason, each month folder includes two files, 'ficheros0' and 'ficheros1', that contain the set of filenames for that month. Therefore, for each normally measured we have 24 data files and also 24 information files for each sensor. Each hour data file occupies 1.8 MB, so each month has roughly a data volume of 2.6 GB.本文件夹包含对应2013年（3月及当月之后）与2017年（1月、2月）的子文件夹，存储内华达山脉极低频（Extremely Low Frequency, ELF）台站的时域原始数据。每个年份下均按月份设置子文件夹，文件夹名称采用四位数字编码，前两位为年份后两位、后两位为月份，例如1412代表2014年12月的原始数据。各月文件夹内均存放对应各传感器、各小时的数据与信息文件。单个数据文件存储约1小时时长的测量数据，文件名以固定前缀"smplGRTU1_sensor_"开头，后续字段依次用于标识所用传感器（0代表南北向（North-South, NS），1代表东西向（East-West, EW））、测量日期与起始记录时间。例如，文件名smplGRTU1_sensor_0_1412010430代表由南北向磁强计测得的数据，对应2014年12月1日04时30分起始的测量任务。配套信息文件与数据文件同名，但后缀为_info.txt。由于测量起始时间不固定，各文件夹内的文件名并非完全统一。因此各月文件夹均包含两个文件：'ficheros0'与'ficheros1'，用于存储该月的全部文件名集合。因此，每个传感器在常规测量场景下，每月对应24个数据文件与24个信息文件。单小时数据文件大小约为1.8 MB，因此单月数据总容量约为2.6 GB。