HiWATER: Dataset of hydrometeorological observation network (eddy covariance system of Sidaoqiao superstation, 2017)

The data set contains the observation data of the eddy covariance system of Sidaoqiao superstation which is located along the lower reaches of the Heihe Hydrometeorological observation network, and the data set covers data from January 1, 2017 to December 31, 2017. The station is located in Sidao Bridge, Ejina Banner, Inner Mongolia, and the underlying surface is Tamarix. The latitude and longitude of the observation station is 101.1374E, 42.0012N, and the altitude is 873 m. The height of the eddy covariance system is 8 meters, the sampling frequency is 10Hz, the ultrasonic orientation is positive north, and the distance between the ultrasonic wind speed and temperature monitor (CSAT3) and the CO2/H2O analyzer (Li7500) is 15cm.The original observation data of the eddy covariance system is 10 Hz, and the released data is a 30-minute data processed by Eddypro software. The main steps of the processing include: outlier eliminating, delay time correction, coordinates rotation (secondary coordinates rotation), frequency response correction, ultrasonic virtual temperature correction and density (WPL) correction, etc. Meanwhile, the quality evaluation of each flux value was performed,mainly includes atmospheric stability (Δst) test and turbulence similarity (ITC) test. The 30-min flux value output of Eddypro software was also screened: (1) Data from the instrument error was eliminated; (2) Data obtained with one hour before and after precipitation was removed; (3) Data with a deletion rate greater than 10% of the 10 Hz raw data every 30 minutes was eliminated; (4) Observation data of weak turbulence at night (u* less than 0.1 m/s) was excluded. The average period of observation data is 30 minutes, 48 data per day, and the missing data is marked as -6999. The data was missing due to Li7500 calibration of the eddy system on April 7 and 8; the suspicious data caused by instrument drift and other reasons was marked by red fonts.Published observation data include: date/time Date/Time, wind direction(°), horizontal wind speed(m/s), lateral wind speed standard deviation(m/s), ultrasonic virtual temperature (°C), water vapor density (g/m3), carbon dioxide concentration(mg/m3), friction velocity (m/s), length (m), sensible heat flux(W/m2), latent heat flux (W/m2), carbon dioxide flux (mg/(m2s)), sensible heat flux quality identification QA_Hs, latent heat flux quality identification QA_LE, carbon dioxide flux quality identification QA_Fc. The quality identification of sensible heat, latent heat, and carbon dioxide flux is divided into three levels (quality mark 0: (Δst <30, ITC<30); 1: (Δst <100, ITC<100); the rest is 2). The meaning of the data time, such as 0:30 represents an average data of 0:00-0:30; the data is stored in *.xls format.For hydrometeorological network or station information, please refer to Li et al. (2013). For observation data processing, please refer to Liu et al. (2011).

本数据集收录了位于黑河水文气象观测网络下游的思道桥超级站的涡度协方差系统观测数据，数据覆盖时间范围为2017年1月1日至2017年12月31日。该观测站坐落于内蒙古自治区鄂尔多斯市鄂托克旗思道桥，其地表覆盖为柽柳。观测站地理坐标为东经101.1374度，北纬42.0012度，海拔高度为873米。涡度协方差系统高度为8米，采样频率为10Hz，超声波方位朝向正北，超声波风速与温度监测仪（CSAT3）与二氧化碳/水汽分析仪（Li7500）之间的距离为15厘米。涡度协方差系统的原始观测数据频率为10Hz，发布的数据为经过Eddypro软件处理的30分钟数据。数据处理的主要步骤包括：剔除异常值、延迟时间校正、坐标旋转（次坐标旋转）、频率响应校正、超声波虚拟温度校正及密度（WPL）校正等。同时，对每个通量值进行了质量评估，主要包括大气稳定性（Δst）测试和湍流相似性（ITC）测试。Eddypro软件输出的30分钟通量值也进行了筛选：（1）消除仪器误差数据；（2）移除降水前后一小时内获得的数据；（3）每30分钟消除10Hz原始数据删除率超过10%的数据；（4）排除夜间弱湍流（u*小于0.1 m/s）的观测数据。观测数据的平均周期为30分钟，每日48个数据点，缺失数据以-6999标记。数据缺失是由于涡度系统在4月7日和8日的Li7500校准所致；由仪器漂移等原因引起的可疑数据以红色字体标注。发布的观测数据包括：日期/时间、风向（°）、水平风速（m/s）、横向风速标准差（m/s）、超声波虚拟温度（°C）、水汽密度（g/m3）、二氧化碳浓度（mg/m3）、摩擦速度（m/s）、长度（m）、感热通量（W/m2）、潜热通量（W/m2）、二氧化碳通量（mg/(m2s)）、感热通量质量识别QA_Hs、潜热通量质量识别QA_LE、二氧化碳通量质量识别QA_Fc。感热、潜热和二氧化碳通量的质量识别分为三个等级（质量标记0：（Δst＜30，ITC＜30）；1：（Δst＜100，ITC＜100）；其余为2）。数据时间意义，如0:30表示从0:00至0:30的平均数据；数据存储为*.xls格式。关于水文气象网络或站点的信息，请参阅Li等（2013）的研究。观测数据处理方法请参考Liu等（2011）的研究。