黑河生态水文遥感试验：水文气象观测网数据集（大满超级站涡动相关仪-2017）

该数据集包含了2017年1月1日至2017年12月31日的黑河水文气象观测网中游大满超级站涡动相关仪观测数据。站点位于甘肃省张掖市大满灌区内，下垫面是玉米。观测点的经纬度是100.37223E, 38.85551N，海拔1556.06m。涡动相关仪的架高4.5m，采样频率是10Hz，超声朝向是正北向，超声风速温度仪（CSAT3）与CO2/H2O分析仪（Li7500A）之间的距离是17cm。
涡动相关仪的原始观测数据为10Hz，发布的数据是采用Eddypro软件处理的30分钟数据，其处理的主要步骤包括：野点值剔除，延迟时间校正，坐标旋转（二次坐标旋转），频率响应修正，超声虚温修正和密度（WPL）修正等。同时对各通量值进行质量评价，主要是大气平稳性（Δst）和湍流相似性特征（ITC）的检验。对Eddypro软件输出的30min通量值也进行了筛选：（1）剔除仪器出错时的数据；（2）剔除降水前后1h的数据；（3）剔除10Hz原始数据中每30min内缺失率大于10%的数据；（4）剔除夜间弱湍流的观测数据（u*小于0.1m/s）。观测数据的平均周期为30分钟，一天48个数据，缺失数据标记为-6999。4月3日-4日涡动系统的Li7500A进行标定，8月29日-9月5日采集器的问题，导致数据缺失。
发布的观测数据包括：日期/时间Date/Time，风向Wdir（°），水平风速Wnd（m/s），侧向风速标准差Std_Uy（m/s），超声虚温Tv（℃），水汽密度H2O（g/m3），二氧化碳浓度CO2（mg/m3），摩擦速度Ustar（m/s），奥布霍夫长度L（m），感热通量Hs（W/m2），潜热通量LE（W/m2），二氧化碳通量Fc（mg/(m2s)），感热通量的质量标识QA_Hs，潜热通量的质量标识QA_LE，二氧化碳通量的质量标识QA_Fc。感热、潜热、二氧化碳通量的质量标识分为三级（质量标识0:（Δst <30, ITC<30）; 1: （Δst <100, ITC<100）; 其余为2）。数据时间的含义，如0:30代表0:00-0:30的平均；数据以*.xls格式存储。
水文气象网或站点信息请参考Liu et al. (2018)，观测数据处理请参考Liu et al. (2011)。

This dataset contains eddy covariance observations collected at the Daman Super Station in the middle reaches of the Heihe River Basin, from January 1, 2017 to December 31, 2017. The station is located within the Daman Irrigation District, Zhangye City, Gansu Province, with maize as the underlying surface. The coordinates of the observation point are 100.37223°E, 38.85551°N, and the elevation is 1556.06 m. The eddy covariance system is mounted at a height of 4.5 m, with a sampling frequency of 10 Hz, and the ultrasonic anemometer is oriented towards true north. The distance between the sonic temperature anemometer (CSAT3) and the CO2/H2O analyzer (LI-7500A) is 17 cm.

The raw observations from the eddy covariance system are at 10 Hz. The released data are 30-minute averaged data processed using EddyPro software. The main processing steps include: outlier removal, time lag correction, coordinate rotation (double rotation), frequency response correction, virtual sonic temperature correction, and density (WPL) correction. Meanwhile, quality assessment was conducted for each flux product, mainly including tests of atmospheric stationarity (Δst) and turbulence similarity characteristics (ITC). Additional screening was performed on the 30-minute flux outputs from EddyPro: (1) remove data collected during instrument malfunctions; (2) remove data within 1 hour before and after precipitation events; (3) remove data with a missing rate greater than 10% per 30-minute segment of the 10-Hz raw dataset; (4) remove nocturnal low-turbulence data (u* < 0.1 m/s). The average period of the observation data is 30 minutes, with 48 records per day, and missing values are marked as -6999. Data gaps occurred from April 3 to 4, 2017 due to LI-7500A calibration, and from August 29 to September 5, 2017 due to issues with the data logger.

The released observation data include the following variables: Date/Time, wind direction Wdir (°), horizontal wind speed Wnd (m/s), lateral wind speed standard deviation Std_Uy (m/s), virtual sonic temperature Tv (℃), water vapor density H2O (g/m³), carbon dioxide concentration CO2 (mg/m³), friction velocity Ustar (m/s), Obukhov length L (m), sensible heat flux Hs (W/m²), latent heat flux LE (W/m²), carbon dioxide flux Fc (mg/(m²s)), quality flags for sensible heat flux QA_Hs, latent heat flux QA_LE, and carbon dioxide flux QA_Fc. The quality flags for sensible heat, latent heat, and carbon dioxide fluxes are classified into three levels: Flag 0: (Δst < 30, ITC < 30); Flag 1: (Δst < 100, ITC < 100); all others are Flag 2. The meaning of the data timestamp is as follows: e.g., 0:30 represents the average over the period 0:00–0:30. All data are stored in *.xls format.

Please refer to Liu et al. (2018) for information on the hydrometeorological network and sites, and Liu et al. (2011) for the data processing procedures.