Multi-year measurements of tree motion from an accelerometer on a spruce tree near Niwot Ridge, Colorado

This repository includes 12 Hz three-axis acceleration data from an accelerometer mounted to the bole of a <em>Picea engelmannii</em> (engelmann spruce) next to the C-1 Ameriflux tower at Niwot Ridge LTER, Colorado, USA. The data were recorded from November 2014 through August 2020. More information on the installation can be found in Raleigh et al. (in review, Water Resources Research). The data are stored in netCDF files, chunked based on the collection date when the data were downloaded from the accelerometer. <strong>File metadata:</strong> Filename GCDC_L01_Raw_Data_Niwot_TreeXX_collection_YYYYMMDD.nc where XX = tree number (01 = spruce, 02 = fir) YYYYMMDD = year (YYYY), month (MM), and day (DD) of data collection Each netCDF includes four variables: 1. serial_date = time increment (fractional days), as defined by Matlab: "A serial date number represents the whole and fractional number of days from a fixed, preset date (January 0, 0000) in the proleptic ISO calendar." The serial dates are in mountain standard time (MST) with no adjustments for daylight savings. 2. Ax = acceleration in the vertical direction (counts) 3. Ay = acceleration in the east-west direction (counts) 4. Az = acceleration in the north-south direction (counts) To convert the "counts" unit to gravitational units (g), divide Ax, Ay, and Az each by 2048, as explained in the manufacturer's user manual.本数据集仓库包含安装于美国科罗拉多州尼沃特岭长期生态研究站点（Niwot Ridge LTER）C-1 Ameriflux通量塔旁的<em>恩格尔曼云杉（Picea engelmannii）</em>树干上的加速度计采集的12 Hz三轴加速度数据。数据采集时段为2014年11月至2020年8月。有关该装置的详细安装信息，可参阅Raleigh等人（已投稿至《Water Resources Research》，待刊）的研究。数据以网络通用数据格式（netCDF）存储，按照从加速度计下载数据时的采集日期进行分块。<strong>文件元数据：</strong> 文件名格式为`GCDC_L01_Raw_Data_Niwot_TreeXX_collection_YYYYMMDD.nc`，其中XX为树木编号（01代表云杉，02代表冷杉），YYYYMMDD分别对应数据采集的年、月、日。每个netCDF文件包含四个变量：1. 序列日期编号（serial_date）：时间增量（以天为单位的小数），符合Matlab定义：“序列日期编号代表公历纪年（proleptic ISO calendar）中固定预设日期（公元0年1月0日）以来的整日及小数天数”。该序列日期采用山地标准时间（MST），未进行夏令时调整。2. Ax：垂直方向加速度（单位：计数）3. Ay：东西方向加速度（单位：计数）4. Az：南北方向加速度（单位：计数）。若需将“计数”单位转换为重力单位（g），需将Ax、Ay、Az分别除以2048，具体说明详见制造商用户手册。