祁连山综合观测网：黑河流域地表过程综合观测网（垭口站涡动相关仪-2019）

该数据集包含了2019年1月1日至2019年12月31日的黑河流域地表过程综合观测网上游垭口站涡动相关仪观测数据。站点位于青海省祁连县，下垫面是高寒草甸。观测点的经纬度是100.2421, 38.0142N，海拔4148 m。涡动相关仪的架高3.2m，采样频率是10Hz，超声朝向是正北向，超声风速仪（CSAT3）与CO2/H2O分析仪（Li7500A）之间的距离是15cm。
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。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。该站冬季会出现缺电现象，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九级（质量标识1-3数据质量好，4-6数据质量较好，7-8数据质量较差（比插补数据好）；9数据质量差））。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。
黑河流域地表过程综合观测网或站点信息请参考Liu et al. (2018)和Che et al. (2019)，观测数据处理请参考Liu et al. (2011)。

This dataset contains eddy covariance observational data collected at the Yakou Station of the Heihe River Basin Surface Process Comprehensive Observation Network from January 1, 2019 to December 31, 2019. The station is situated in Qilian County, Qinghai Province, with an underlying surface of alpine meadow. The geographic coordinates of the observation site are 100.2421, 38.0142°N, and the elevation is 4148 m. The eddy covariance system has an installation height of 3.2 m, a sampling frequency of 10 Hz, with the ultrasonic anemometer facing due north. The distance between the ultrasonic anemometer (model CSAT3) and the CO₂/H₂O analyzer (model Li7500A) is 15 cm.

The raw observational data from the eddy covariance system is at 10 Hz, while the released dataset consists of 30-minute averaged data processed using EddyPro software. The primary processing steps include: outlier removal, time lag correction, coordinate rotation (double coordinate rotation), frequency response correction, ultrasonic virtual temperature correction, and density (WPL) correction. Quality assessments were also conducted for each flux value, focusing on atmospheric stationarity (Δst) and turbulent similarity characteristics (ITC). Further screening was applied to the 30-minute flux outputs from EddyPro: (1) removing data collected during instrument failures; (2) excluding data within 1 hour before and after precipitation events; (3) eliminating data segments with a missing rate exceeding 10% in each 30-minute block of the 10 Hz raw data.

The average temporal resolution of the observational data is 30 minutes, yielding 48 data points per day. Missing data is marked as -6999. This station suffers from power outages in winter, resulting in data gaps.

The released observational data includes the following variables: Date/Time, wind direction Wdir (°), horizontal wind speed Wnd (m/s), lateral wind speed standard deviation Std_Uy (m/s), ultrasonic virtual 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 flag for sensible heat flux QA_Hs, quality flag for latent heat flux QA_LE, and quality flag for carbon dioxide flux QA_Fc. The quality flags for sensible heat, latent heat, and carbon dioxide fluxes are graded into nine levels: levels 1–3 represent good data quality, 4–6 represent relatively good data quality, 7–8 represent relatively poor data quality (better than imputed data), and 9 represents poor data quality. The timestamp indicates the averaging period: for example, 0:30 represents the average over 0:00–0:30. All data are stored in *.xls format.

For information about the Heihe River Basin Surface Process Comprehensive Observation Network or individual stations, please refer to Liu et al. (2018) and Che et al. (2019). For details on the observational data processing procedures, please refer to Liu et al. (2011).