IAGOS Adjusted Water Vapor Climatologies

Content The files contain adjusted mean water vapor values based on the IAGOS ICH measurements. The data are provided to a 5x5° grid for different levels of potential temperatureand on pressure. The dataset contains the adjusted water vapor and an error estimate, which is based on the measurement uncertainity as well as the uncertainty of the adjusmtent methdology. Data Coverage Mean values are derived from measurements in the period 1996 to 2022 Data Creation The adjustment methodology is decribed in detail in the following publication, Section 4: Konjari, P. and Rolf, C. and Hegglin, M. I. and Rohs, S. and Li, Y. and Zahn, A. and Bönisch, H. and Krämer, M. and Petzold, A., Water Vapor climatologies in the extra-tropical Upper Troposphere and Lower Stratosphere derived from a Synthesis of Passenger and Research Aircraft Measurements, EGUsphere, doi: 10.5194/egusphere-2024-2360 Application The adjusted water vapor climatologies can be used to further study the spatial and seasonal variability over water vapor in the UTLS. For comparison of the adjusted IAGOS data with other datasets, the data coverage of the adjusted data should be considered. For this purpose, for every bin, the amount of data for every single month of the respective years is provided in the variable 'num_measurements' (dimension: longitude x latitude x theta x nyear x month, with nyear=0 for 1996). Caveats: Because a sufficient amount of data in the order of several thousand measurement points is needed to derive the adjusted mean values, only multi-annual means are provided, and no trends can be derived Uncertainties of the adjustment methodology: The uncertainty of the water vapor data can exceed 10 % and reach up to 20 % for dry stratospheric air masses (<10 ppmv). These uncertainties, provided within the variable 'H2O_gas_err', should always be considered in the analyses. Due to temporal inhomogenety in the amount of data per year and bin (latitude x longitude x Theta), the temporal coverage differs from bin to bin. Hence, differences between bins might also occur because of this reason.### 内容 本数据集文件包含基于IAGOS ICH观测得到的订正后平均水汽数值。数据以5°×5°的网格形式呈现，覆盖不同位温（potential temperature）层级与气压层面。数据集包含订正后的水汽数据以及误差估计值，该误差估计基于观测不确定度与订正方法（adjustment methodology）自身的不确定度。 ### 数据覆盖范围 本数据集的平均数值源自1996年至2022年期间的观测数据。 ### 数据构建方法 订正方法的详细说明详见下述文献的第4章节： Konjari, P.、Rolf, C.、Hegglin, M. I.、Rohs, S.、Li, Y.、Zahn, A.、Bönisch, H.、Krämer, M.、Petzold, A.，《基于民航客机与科研飞机观测合成的热带外对流层上层和平流层下层（Upper Troposphere and Lower Stratosphere，简称UTLS）水汽气候态》，发表于EGUsphere，DOI: 10.5194/egusphere-2024-2360 ### 应用场景 本订正水汽气候态可用于进一步研究UTLS区域内水汽的空间与季节变化特征。 若需将订正后的IAGOS数据与其他数据集进行对比，需考虑订正后数据的覆盖范围。为此，每个数据箱的逐年各月数据量已通过变量`num_measurements`给出，其维度为：经度×纬度×位温（theta）×年数×月份，其中`nyear=0`对应1996年。 ### 注意事项 由于计算订正平均数值需要数千个观测点的足量数据支撑，本数据集仅提供多年平均结果，无法推导趋势变化。 订正方法带来的不确定度：对于干燥平流层气团（体积混合比低于10 ppmv），水汽数据的不确定度可超过10%，最高可达20%。该不确定度以变量`H2O_gas_err`的形式提供，在数据分析中必须予以考虑。 由于每年各数据箱（纬度×经度×位温）的数据量存在时间不均匀性，不同数据箱的时间覆盖范围存在差异。因此，不同数据箱之间的差异也可能由此产生。