North American CO 2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion
North American CO 2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion
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北美 CO 2 交换：模型估计值与精细大气反演结果的相互比较
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
A. Michalak
中科院分区：
文献类型：
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作者：
S. Gourdji;K. Mueller;V. Yadav;D. Huntzinger;A. Andrews;M. Trudeau;G. Pétron;T. Nehrkorn;J. Eluszkiewicz;J. Henderson;D. Wen;John C. Lin;M. Fischer;C. Sweeney;A. Michalak
抽象的。大气反演模型有可能通过利用在通量变化较大的地区收集的近地表CO2混合比观测数据来量化区域、次大陆尺度的CO2通量。本研究提出了一系列的区域地质统计反演模型（GIM）在北美2004年的结果，并使用它们作为相互比较的基础，其他反演研究和估计从生物圈模型收集通过北美碳计划区域和大陆临时综合。由于GIM方法不需要明确的先验通量估计，并在精细的时空尺度（即1° × 1°，本研究中为3小时）下解析通量，因此它避免了时间和空间聚合误差，并允许从大气数据中恢复相对于先前反演研究的真实空间模式。从GIM反演只使用现有的大气观测和精细尺度的化石燃料库存的结果被用来确认库存和反演设置的质量。另外，包括北美区域再分析的辅助变量的反演发现，与生物圈碳循环的生理理解一致的通量推断关系。GIM结果与自下而上的生物圈模型的比较显示，在相对于休眠季节的增长更强的协议，部分原因是大多数的生物圈模型不完全代表农业土地管理的做法和剩余的生物量和收获的产品的命运。与早期反演研究的比较表明，聚合误差可能是以前次大陆尺度通量估计的偏差来源，特别是对于在粗尺度上调整通量并使用长期平均大气观测的反演。最后，虽然GIM反演中使用的大陆CO2边界条件对空间格局的影响很小，但它们对大陆碳收支有很大的影响，使用两组合理的边界CO2混合比导致大陆总通量相差0.8 PgC yr−1。总体而言，这种相互比较研究有助于评估在估计区域尺度CO2通量方面的科学状况，同时指出未来自上而下和自下而上建模工作的改进方向。
Abstract. Atmospheric inversion models have the potential to quantify CO2 fluxes at regional, sub-continental scales by taking advantage of near-surface CO2 mixing ratio observations collected in areas with high flux variability. This study presents results from a series of regional geostatistical inverse models (GIM) over North America for 2004, and uses them as the basis for an inter-comparison to other inversion studies and estimates from biospheric models collected through the North American Carbon Program Regional and Continental Interim Synthesis. Because the GIM approach does not require explicit prior flux estimates and resolves fluxes at fine spatiotemporal scales (i.e. 1° × 1°, 3-hourly in this study), it avoids temporal and spatial aggregation errors and allows for the recovery of realistic spatial patterns from the atmospheric data relative to previous inversion studies. Results from a GIM inversion using only available atmospheric observations and a fine-scale fossil fuel inventory were used to confirm the quality of the inventory and inversion setup. An inversion additionally including auxiliary variables from the North American Regional Reanalysis found inferred relationships with flux consistent with physiological understanding of the biospheric carbon cycle. Comparison of GIM results with bottom-up biospheric models showed stronger agreement during the growing relative to the dormant season, in part because most of the biospheric models do not fully represent agricultural land-management practices and the fate of both residual biomass and harvested products. Comparison to earlier inversion studies pointed to aggregation errors as a likely source of bias in previous sub-continental scale flux estimates, particularly for inversions that adjust fluxes at the coarsest scales and use atmospheric observations averaged over long periods. Finally, whereas the continental CO2 boundary conditions used in the GIM inversions have a minor impact on spatial patterns, they have a substantial impact on the continental carbon budget, with a difference of 0.8 PgC yr−1 in the total continental flux resulting from the use of two plausible sets of boundary CO2 mixing ratios. Overall, this inter-comparison study helps to assess the state of the science in estimating regional-scale CO2 fluxes, while pointing towards the path forward for improvements in future top-down and bottom-up modeling efforts.