Met City meteorological and surface flux measurements (Level 3 Final), Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC), central Arctic, October 2019 - September 2020.

Final, processed (Level 3) measurements and derived parameters from a collection of instruments at the Met City location within the Central Observatory of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition drifting with the central Arctic sea ice from October 2019 through September 2020. Measurements are from a 10-meter meteorological and flux tower, a radiation suite (operated by the DOE Atmospheric Radiation Measurement Program), and at times also a meteorological mast located nearby. The collective MET CITY systems measured many parameters of the surface energy budget, air-ice momentum flux, near-surface meteorology, and local position. Measurements of meteorology and high-resolution 3-dimensional winds were observed at nominal heights of 2-, 6-, and 10-m, with some measurements at either 30- or 23-m when the mast was also operational. Measurements of upwelling broadband radiation were made at a nominal height of 3 m, while measurements of downwelling broadband radiation were made at a nominal height of 1.5 m above the ice surface. The measurements are included in two netCDF files per day. The “1min” mosmet files are comprised of 1-min averages of measured and derived variables, including near-surface meteorology, surface skin temperature, snow depth, radiative fluxes, and position. The “10min” mosseb files are 10-min averages of the same variables as in the 1-min files and also include calculations of turbulent sensible and latent heat fluxes, momentum flux, and other turbulence parameters using both eddy covariance and bulk methodologies, all valid for the 10-min intervals. Both of these file types also contain a “_qc” variable paired with each measurement variable, or family of variables, that is a temporally-matched quality control code: 0 = good data, 1 = caution (data may be suspect), 2 = bad data, 3 = engineering (data was collected for testing purposes and is unsuitable for scientific research), and -1 = missing (no data was collected). Data with associated qc flag = 2 or qc flag = 3 have been removed from the data set as they are not appropriate for scientific use. Data with associated qc flag = 1 are retained in the data set, but should be considered with caution and their removal from analysis is at the discretion of the user. An independent flag variable, pertaining specifically to the collection of turbulence variables, was devised to document times when the prevailing wind direction was influenced by non-natural structures on the sea ice and the data should be treated with caution. A detailed documentation of the measurement conditions, the processing steps taken to construct this data set, and other caveats and uncertainties are provided in an accompanying published data manuscript (Cox et al. 2023). For the scientific purposes of most users, we recommend use of the Level 3 data files, as these include only the best estimates of essential climate variables. Level 2 data is useful for those that want enhanced turbulence diagnostics parameters and/or to consider the use of some data that has been flagged as unsuitable for research. These data were obtained via a collaboration among the University of Colorado, NOAA Physical Sciences Laboratory, NOAA Global Ocean Monitoring and Observing (GOMO) program, Department of Energy Atmospheric Radiation Measurement Program, and University of Leeds, UK. Cox, C.J., M. Gallagher, M.D. Shupe, P.O.G. Persson, A. Solomon, C. W. Fairall, T. Ayers, B. Blomquist, I. Brooks, D. Costa, A. Grachev, D. Gottas, J. Hutchings, M. Kutchenreiter, J. Leach, S.M. Morris, V. Morris, J. Osborn, S. Pezoa, A. Preusser, L. Riihimaki, and T. Uttal (2023): Continuous observations of the surface energy budget and meteorology over Arctic sea ice during MOSAiC. Nature Scientific Data.

本数据集包含2019年10月至2020年9月期间，随北极中央海冰漂流的北极气候多学科漂流观测站（Multidisciplinary drifting Observatory for the Study of Arctic Climate, MOSAiC）考察队中央观测站Met City站点的各类仪器经最终处理的3级（Level 3）测量数据与衍生参数。

测量数据源自10米气象与通量塔、一套由美国能源部大气辐射测量计划（Department of Energy Atmospheric Radiation Measurement Program）运行的辐射套件，部分时段还同步使用了附近的气象桅杆。MET CITY整套观测系统获取了地表能量收支、冰-气动量通量、近地面气象条件与本地位置等多类参数。

气象要素与高分辨率三维风场的观测高度分别为标称2米、6米和10米；当配套气象桅杆正常运行时，部分观测还会在30米或23米高度开展。上行宽带辐射的观测高度为冰面上方标称3米，下行宽带辐射的观测高度则为冰面上方标称1.5米。

每日数据存储为两个netCDF格式文件。其中"1min"类mosmet文件包含测量与衍生变量的1分钟平均值，涵盖近地面气象、地表肤温、雪深、辐射通量与位置信息。"10min"类mosseb文件则包含与1分钟文件相同变量的10分钟平均值，同时还利用涡动协方差（eddy covariance）与整体法（bulk methodologies）计算得到湍流感热通量、潜热通量、动量通量及其他湍流参数，所有结果均对应10分钟的观测时段。

两类文件均为每个测量变量（或变量组）配备了一个"_qc"质量控制（quality control, QC）变量，该变量为与观测时刻匹配的质量控制编码：0代表数据合格，1代表需谨慎（数据可能存疑），2代表数据无效，3代表工程测试数据（仅用于测试，不适用于科学研究），-1代表数据缺失（未采集到有效数据）。本数据集已移除质量控制标记为2或3的数据，因其不适用于科学研究；质量控制标记为1的数据保留在数据集中，但需谨慎使用，是否在分析中剔除此类数据由使用者自行决定。

另有一个独立的标记变量，专门针对湍流变量集合，用于记录盛行风向受海冰上非人工建筑影响的时段，此类数据需谨慎处理。本数据集的观测条件说明、数据处理流程及其他注意事项与不确定性，已在配套已发表的学术论文（Cox等，2023）中详细阐述。

针对多数使用者的科研需求，我们推荐使用3级（Level 3）数据文件，因其仅包含关键气候变量的最优估算结果。2级（Level 2）数据则适用于需要更丰富湍流诊断参数，或希望纳入部分被标记为不适用于研究的数据的使用者。

本数据集由科罗拉多大学、美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）物理科学实验室、NOAA全球海洋监测与观测（Global Ocean Monitoring and Observing, GOMO）项目、美国能源部大气辐射测量计划以及英国利兹大学合作提供。

Cox, C.J., M. Gallagher, M.D. Shupe, P.O.G. Persson, A. Solomon, C. W. Fairall, T. Ayers, B. Blomquist, I. Brooks, D. Costa, A. Grachev, D. Gottas, J. Hutchings, M. Kutchenreiter, J. Leach, S.M. Morris, V. Morris, J. Osborn, S. Pezoa, A. Preusser, L. Riihimaki, 与 T. Uttal (2023): Continuous observations of the surface energy budget and meteorology over Arctic sea ice during MOSAiC. 《自然·科学数据》（Nature Scientific Data）.