Qilian Mountains integrated observatory network: Dataset of Heihe integrated observatory network (eddy covariance system of Dashalong station, 2018)

This dataset contains the flux measurements from the Dashalong station eddy covariance system (EC) in the upperstream reaches of the Heihe integrated observatory network from January 1 to December 31 in 2018. The site (98.9406° E, 38.8399° N) was located in the Qilian County in Qinghai Province. The elevation is 3739 m. The EC was installed at a height of 4.5 m, and the sampling rate was 10 Hz. The sonic anemometer faced north, and the separation distance between the sonic anemometer and the CO2/H2O gas analyzer (CSAT3&Li7500RS) was 0.15 m.The raw data acquired at 10 Hz were processed using the Eddypro post-processing software, including the spike detection, lag correction of H2O/CO2 relative to the vertical wind component, sonic virtual temperature correction, coordinate rotation (2-D rotation), corrections for density fluctuation (Webb-Pearman-Leuning correction), and frequency response correction. The EC data were subsequently averaged over 30 min periods. The observation data quality was divided into three classes according to the quality assessment method of stationarity (Δst) and the integral turbulent characteristics test (ITC): class 1-3 (high quality), class 4-6 (good), class 7-8 (poor, better than gap filling data), class9 (rejected). In addition to the above processing steps, the half-hourly flux data were screened in a four-step procedure: (1) data from periods of sensor malfunction were rejected; (2) data collected before or after 1 h of precipitation were rejected; (3) incomplete 30 min data were rejected when the missing data constituted more than 3% of the 30 min raw record; and (4) data were rejected at night when the friction velocity (u*) was less than 0.1 m/s. There were 48 records per day, and the missing data were replaced with -6999. Suspicious data were marked in red. Data during September 27 to November 14, 2018 were missing due to the sensor calibration of sonic anemometer.The released data contained the following variables: data/time, wind direction (Wdir, °), wind speed (Wnd, m/s), the standard deviation of the lateral wind (Std_Uy, m/s), virtual temperature (Tv, ℃), H2O mass density (H2O, g/m3), CO2 mass density (CO2, mg/m3), friction velocity (ustar, m/s), stability (z/L), sensible heat flux (Hs, W/m2), latent heat flux (LE, W/m2), carbon dioxide flux (Fc, mg/ (m2s)), quality assessment of the sensible heat flux (QA_Hs), quality assessment of the latent heat flux (QA_LE), and quality assessment of the carbon flux (QA_Fc). In this dataset, the time of 0:30 corresponds to the average data for the period between 0:00 and 0:30; the data were stored in *.xls format. Detailed information can be found in the suggested references.For more information, please refer to Liu et al. (2018) (for sites information), Liu et al. (2011) for data processing) in the Citation section.

本数据集收录了自2018年1月1日至12月31日期间，黑河综合观测网络上游河段Dashalong站点涡度协方差系统（EC）的通量测量数据。该站点（经度98.9406° E，纬度38.8399° N）位于青海省祁连县，海拔高度为3739米。涡度协方差仪安装于4.5米高度，采样频率为10赫兹。风速仪朝向北方，与二氧化碳/水汽气体分析仪（CSAT3&Li7500RS）之间的间距为0.15米。原始10赫兹数据经Eddypro后处理软件进行处理，包括尖峰检测、相对垂直风速成分的H2O/CO2滞后校正、风速虚拟温度校正、坐标旋转（二维旋转）、密度波动校正（Webb-Pearman-Leuning校正）以及频率响应校正。随后，将涡度协方差数据按30分钟周期进行平均。根据稳定性（Δst）和积分湍流特性测试（ITC）的质量评估方法，将观测数据质量划分为三个等级：1-3级（高质量）、4-6级（良好）、7-8级（较差，优于插补数据）、9级（被拒绝）。除上述处理步骤外，半小时通量数据经过四步筛选程序：1）拒绝传感器故障期间的数据；2）拒绝在降水前后1小时内收集的数据；3）当缺失数据占30分钟原始记录的3%以上时，拒绝不完整的30分钟数据；4）在摩擦速度（u*）小于0.1米/秒的夜间拒绝数据。每日记录48条，缺失数据用-6999替代。可疑数据以红色标注。2018年9月27日至11月14日期间，由于风速仪的校准，数据缺失。发布的数据包含以下变量：数据/时间、风向（Wdir，°）、风速（Wnd，m/s）、横向风速的标准差（Std_Uy，m/s）、虚拟温度（Tv，℃）、水汽质量密度（H2O，g/m3）、二氧化碳质量密度（CO2，mg/m3）、摩擦速度（ustar，m/s）、稳定性（z/L）、感热通量（Hs，W/m2）、潜热通量（LE，W/m2）、二氧化碳通量（Fc，mg/(m2s)）、感热通量质量评估（QA_Hs）、潜热通量质量评估（QA_LE）和碳通量质量评估（QA_Fc）。在本数据集中，0:30的时间点对应于0:00至0:30期间的平均数据；数据以*.xls格式存储。详细信息可参考建议的参考文献。欲了解更多信息，请参阅引用部分的Liu等人（2018年）（关于站点信息），Liu等人（2011年）（关于数据处理）。