Three-hourly net ecosystem exchange (NEE) is estimated at spatial scales of 0.25^∘ over the European continent, based on the pre-operational inverse modelling framework “CarboScope Regional” (CSR) for the years 2006 to 2019. To assess the uncertainty originating from the choice of a priori flux models and observational data, ensembles of inversions were produced using three terrestrial ecosystem flux models, two ocean flux models, and three sets of atmospheric stations. We find that the station set ensemble accounts for 61 % of the total spread of the annually aggregated fluxes over the full domain when varying all these elements, while the biosphere and ocean ensembles resulted in much smaller contributions to the spread of 28 % and 11 %, respectively. These percentages differ over the specific regions of Europe, based on the availability of atmospheric data. For example, the spread of the biosphere ensemble is prone to be larger in regions that are less constrained by CO₂ measurements. We investigate the impact of unprecedented increase in temperature and simultaneous reduction in soil water content (SWC) observed in 2018 and 2019 on the carbon cycle. We find that NEE estimates during these 2 years suggest an impact of drought occurrences represented by the reduction in net primary productivity (NPP), which in turn leads to less CO₂ uptake across Europe in 2018 and 2019, resulting in anomalies of up to 0.13 and 0.07 PgC yr⁻¹ above the climatological mean, respectively. Annual temperature anomalies also exceeded the climatological mean by 0.46 ^∘C in 2018 and by 0.56 ^∘C in 2019, while Standardised Precipitation–Evaporation Index (SPEI) anomalies declined to −0.20 and −0.05 SPEI units below the climatological mean in both 2018 and 2019, respectively. Therefore, the biogenic fluxes showed a weaker sink of CO₂ in both 2018 and 2019 (−0.22 ± 0.05 and −0.28 ± 0.06 PgC yr⁻¹, respectively) in comparison with the mean −0.36 ± 0.07 PgC yr⁻¹ calculated over the full analysed period (i.e. 14 years). These translate into a continental-wide reduction in the annual sink by 39 % and 22 %, respectively, larger than the typical year-to-year standard deviation of 19 % observed over the full period.

中文翻译：

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来自运行前集合反演系统的 2006-2019 年欧洲净生态系统交换 (NEE) 估计

三小时净生态系统交换 (NEE) 估计空间尺度为 0.25 ^∘在欧洲大陆上空，基于 2006 年至 2019 年的运行前反演建模框架“CarboScope 区域”（CSR）。为了评估源自选择先验通量模型和观测数据的不确定性，产生了反演集合使用三个陆地生态系统通量模型、两个海洋通量模型和三组大气站。我们发现，当改变所有这些元素时，台站集集合占整个域年总通量总分布的 61 %，而生物圈和海洋集合对 28 % 和 11 % 的分布的贡献要小得多， 分别。根据大气数据的可用性，这些百分比在欧洲的特定地区有所不同。例如，_{2 次}测量。我们调查了 2018 年和 2019 年观察到的前所未有的温度升高和土壤含水量 (SWC) 的同时降低对碳循环的影响。我们发现，这 2 年的 NEE 估计表明干旱发生的影响表现为净初级生产力 (NPP) 的降低，这反过来又导致 2018 年和 2019 年整个欧洲的 CO ₂吸收减少，导致异常值高达 0.13和 0.07 PgC yr ^-1分别高于气候平均值。2018 年和 温度异常也分别超过气候平均值 0.46  ^{∘ C 和 0.56 ∘} C，而标准化降水蒸发指数 (SPEI) 异常下降到 -0.20和-0.05 SPEI 单位分别低于 2018 年和 2019 年的气候平均值。因此，生物通量在 2018 年和 2019年均显示出较弱的 CO ₂汇（分别为-0.22  ±  0.05 和-0.28  ±  0.06 PgC yr  -1 ^），^而在完整分析期（即 14 年）。这意味着整个大陆的年汇分别减少了 39% 和 22%，大于在整个期间观察到的 19% 的典型逐年标准差。