祁连山综合观测网：兰州大学寒旱区科学观测网络CARN（西营河站涡动相关仪-2019）

该数据集包含了2019年4月18日至2019年12月31日的兰州大学寒旱区科学观测网络西营河站涡动相关仪观测数据。站点位于青海海北门源县仙米乡讨拉村，下垫面是高寒草甸。观测点的经纬度是101.855E，37.561N，海拔3616m。涡动相关仪的架高4m，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。9.10-10.22日数据缺失。
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（较插补数据好）；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。

This dataset contains eddy covariance system observations from the Xiying River Station of the Cold and Arid Regions Science Observation Network of Lanzhou University, covering the period from April 18, 2019 to December 31, 2019. The station is located in Taola Village, Xianmi Township, Menyuan County, Haibei, Qinghai, with an underlying surface of alpine meadow. The geographic coordinates of the observation site are 101.855°E, 37.561°N, and the elevation is 3616 m. The eddy covariance system has an installation height of 4 m, a sampling frequency of 10 Hz, and the ultrasonic anemometer faces due north. The distance between the ultrasonic anemometer/thermometer (CSAT3) and the CO2/H2O analyzer (Li7500A) is 17 cm.

The raw observation data of the eddy covariance system is collected at 10 Hz, while the released dataset provides 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, among others. Quality assessment was conducted for each flux product, mainly involving tests of atmospheric stationarity (Δst) and turbulence similarity characteristics (ITC). Additional screening was applied to the 30-minute flux outputs from EddyPro: (1) exclude data collected during instrument failures; (2) remove records with a missing rate exceeding 10% within each 30-minute window of the 10 Hz raw data. The average temporal resolution of the dataset is 30 minutes, yielding 48 data points per day, with missing values marked as -6999. Data from September 10 to October 22 is unavailable.

The released observation variables include: 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 of sensible heat flux QA_Hs, quality flag of latent heat flux QA_LE, and quality flag of carbon dioxide flux QA_Fc. The quality flags for sensible heat, latent heat, and carbon dioxide fluxes are categorized into nine levels: flags 1–3 denote good data quality, 4–6 denote moderate data quality, 7–8 denote poor data quality (better than interpolated data), and 9 denote very poor data quality. The timestamp notation follows that, for example, 0:30 represents the average over the period 0:00–0:30. All data are stored in *.xls format.