European methane emissions estimated using atmospheric inversions

Methane emission estimates are presented from four different atmospheric inversion frameworks for the period 2005 to 2018. These flux estimates were prepared in the framework of the H2020 project, VERIFY. Included are the gridded fluxes at monthly temporal resolution and either at 0.5x0.5 or 1.0x1.0 degrees spatial resolution depending on the inversion. Although two of the inversions present global gridded fluxes, the target region for all inversions is geographical Europe. Also included are country total emissions for all EU27 + UK countries at monthly resolution. All inversions use the same prior flux estimate, which includes empirical and process-based model estimates for all anthropogenic sources as well as for natural sources from geological manifestations, lakes, peatland and mineral soils. The files are named after the inversion frameworks (see below). The datasets are the following: Carbon-Tracker Europe CH₄ (in the filenames this is abbreviated as CTE): a Bayesian inversion framework based on the Eulerian atmospheric transport model, TM5, and using an Ensemble Kalman Filter algorithm. The gridded fluxes are at 1.0x1.0 degrees resolution and in units of kgCH₄/m²/month. The gridded flux file contains variables for the prior and posterior fluxes from soils (bio_flux_prior and bio_flux_opt), and from anthropogenic sources (anth_flux_prior and anth_flux_opt) and their prior and posterior uncertainties (bio_flux_prior_std, bio_flux_opt_std, anth_flux_prior_std and anth_flux_opt_std) calculated as the standard deviation of the ensemble members. Also included are fluxes from wildfires (fire_flux_imp), ocean (ocn_flux_imp), geological manifestations (geol_flux_imp), and the total prior and posterior flux (total_flux_pri and total_flux_opt) and their uncertainties (total_flux_pri_std and total_flux_opt_std). FLEXINVERT: a Bayesian inversion framework based on the Lagrangian atmospheric transport model, FLEXPART. The gridded fluxes are at 0.5x0.5 degrees resolution and are in units of kgCH₄/m²/y. The gridded flux file contains variables for the prior and posterior total flux (FCH4_TOT_pri and FCH4_TOT_post), the posterior flux after applying an inequality constraint (FCH4_TOT_post_constrained), and the prior and posterior flux uncertainties (FCH4_TOT_epri and FCH4_TOT_epos). FLEXPART-ExKF (in the filenames this is abbreviated as FLEXKF): a Bayesian inversion framework based on the Lagrangian atmospheric transport model, FLEXPART, using an Extended Kalman Filter algorithm. The gridded fluxes are at 0.5x0.5 degrees resolution and are in units of kgCH₄/m²/h. The gridded flux file contains variables for the prior and posterior total flux (FCH4_PRIOR and FCH4_POST), and the prior and posterior flux uncertainties (FCH4_PRIOR_UNCERT and FCH4_POST_UNCERT). TM5-4DVAR: a Bayesian inversion framework based on the Eulerian atmospheric transport model, TM5, and using a 4D-var algorithm. The gridded fluxes are at 1.0x1.0 degrees resolution and in units of kgCH₄/m²/h. The gridded flux file contains variables for the prior and posterior total flux (FCH4_PRIOR and FCH4_POST).本数据集提供了2005年至2018年间基于四种不同大气反演框架得到的甲烷排放估算结果。这些通量估算成果依托欧盟地平线2020（H2020）计划VERIFY项目框架完成。 数据集包含时间分辨率为月度的网格化通量数据，空间分辨率根据反演框架不同，分为0.5×0.5度或1.0×1.0度。尽管其中两套反演提供了全球网格化通量，但所有反演的目标区域均为欧洲地理区域。 此外，数据集还包含欧盟27国+英国（EU27 + UK）所有国家的月度总排放量数据。 所有反演框架均采用统一的先验通量估算值，该值涵盖了基于经验和过程模型得到的所有人为源排放估算，以及来自地质露头、湖泊、泥炭地和矿质土壤的自然源排放估算。 数据集文件以所用反演框架命名（详见下文）。具体数据集如下： 1. 欧洲碳追踪器甲烷（Carbon-Tracker Europe CH₄，文件中缩写为CTE）：基于欧拉大气传输模型TM5构建的贝叶斯反演框架，采用集合卡尔曼滤波（Ensemble Kalman Filter）算法。其网格化通量的空间分辨率为1.0×1.0度，单位为kgCH₄/m²/月。网格化通量文件包含土壤源（bio_flux_prior与bio_flux_opt）、人为源（anth_flux_prior与anth_flux_opt）的先验与后验通量，以及对应的先验和后验不确定性（bio_flux_prior_std、bio_flux_opt_std、anth_flux_prior_std与anth_flux_opt_std），上述不确定性以集合成员的标准差计算得到。此外，文件还包含野火通量（fire_flux_imp）、海洋通量（ocn_flux_imp）、地质露头通量（geol_flux_imp），以及总先验和后验通量（total_flux_pri与total_flux_opt）及其不确定性（total_flux_pri_std与total_flux_opt_std）。 2. FLEXINVERT：基于拉格朗日大气传输模型FLEXPART构建的贝叶斯反演框架。其网格化通量的空间分辨率为0.5×0.5度，单位为kgCH₄/m²/年。网格化通量文件包含总先验通量与总后验通量（FCH4_TOT_pri与FCH4_TOT_post）、施加不等式约束后的后验通量（FCH4_TOT_post_constrained），以及先验和后验通量不确定性（FCH4_TOT_epri与FCH4_TOT_epos）。 3. FLEXPART-ExKF（文件中缩写为FLEXKF）：基于拉格朗日大气传输模型FLEXPART构建的贝叶斯反演框架，采用扩展卡尔曼滤波（Extended Kalman Filter）算法。其网格化通量的空间分辨率为0.5×0.5度，单位为kgCH₄/m²/小时。网格化通量文件包含总先验通量与总后验通量（FCH4_PRIOR与FCH4_POST），以及先验和后验通量不确定性（FCH4_PRIOR_UNCERT与FCH4_POST_UNCERT）。 4. TM5-4DVAR：基于欧拉大气传输模型TM5构建的贝叶斯反演框架，采用四维变分（4D-var）算法。其网格化通量的空间分辨率为1.0×1.0度，单位为kgCH₄/m²/小时。网格化通量文件包含总先验通量与总后验通量（FCH4_PRIOR与FCH4_POST）。