Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique
We present top-down constraints on global monthly N[subscript 2]O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well current observations can constrain the spa...
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| Format: | Article |
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Copernicus Publications
2018
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| Online Access: | http://hdl.handle.net/1721.1/114271 |
| _version_ | 1826199749862096896 |
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| author | Wells, Kelley C. Millet, Dylan B. Bousserez, Nicolas Henze, Daven K. Griffis, Timothy J. Chaliyakunnel, Sreelekha Dlugokencky, Edward J. Saikawa, Eri Prinn, Ronald G. Young, Dickon Weiss, Ray F. Dutton, Geoff S. Elkins, James W. Krummel, Paul B. Langenfelds, Ray Steele, L. Paul O'Doherty, Simon Xiang, Gao |
| author2 | Massachusetts Institute of Technology. Joint Program on the Science & Policy of Global Change |
| author_facet | Massachusetts Institute of Technology. Joint Program on the Science & Policy of Global Change Wells, Kelley C. Millet, Dylan B. Bousserez, Nicolas Henze, Daven K. Griffis, Timothy J. Chaliyakunnel, Sreelekha Dlugokencky, Edward J. Saikawa, Eri Prinn, Ronald G. Young, Dickon Weiss, Ray F. Dutton, Geoff S. Elkins, James W. Krummel, Paul B. Langenfelds, Ray Steele, L. Paul O'Doherty, Simon Xiang, Gao |
| author_sort | Wells, Kelley C. |
| collection | MIT |
| description | We present top-down constraints on global monthly N[subscript 2]O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well current observations can constrain the spatial distribution of global N[subscript 2]O emissions. The strategies include (1) a standard 4D-Var inversion at native model resolution (4° × 5°), (2) an inversion for six continental and three ocean regions, and (3) a fast 4D-Var inversion based on a novel dimension reduction technique employing randomized singular value decomposition (SVD). The optimized global flux ranges from 15.9 Tg N yr[superscript −1] (SVD-based inversion) to 17.5–17.7 Tg N yr[superscript −1] (continental-scale, standard 4D-Var inversions), with the former better capturing the extratropical N[subscript 2]O background measured during the HIAPER Pole-to-Pole Observations (HIPPO) airborne campaigns. We find that the tropics provide a greater contribution to the global N[superscript 2]O flux than is predicted by the prior bottom-up inventories, likely due to underestimated agricultural and oceanic emissions. We infer an overestimate of natural soil emissions in the extratropics and find that predicted emissions are seasonally biased in northern midlatitudes. Here, optimized fluxes exhibit a springtime peak consistent with the timing of spring fertilizer and manure application, soil thawing, and elevated soil moisture. Finally, the inversions reveal a major emission underestimate in the US Corn Belt in the bottom-up inventory used here. We extensively test the impact of initial conditions on the analysis and recommend formally optimizing the initial N[superscript 2]O distribution to avoid biasing the inferred fluxes. We find that the SVD-based approach provides a powerful framework for deriving emission information from N2O observations: by defining the optimal resolution of the solution based on the information content of the inversion, it provides spatial information that is lost when aggregating to political or geographic regions, while also providing more temporal information than a standard 4D-Var inversion. |
| first_indexed | 2024-09-23T11:25:31Z |
| format | Article |
| id | mit-1721.1/114271 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T11:25:31Z |
| publishDate | 2018 |
| publisher | Copernicus Publications |
| record_format | dspace |
| spelling | mit-1721.1/1142712022-10-01T03:30:37Z Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique Wells, Kelley C. Millet, Dylan B. Bousserez, Nicolas Henze, Daven K. Griffis, Timothy J. Chaliyakunnel, Sreelekha Dlugokencky, Edward J. Saikawa, Eri Prinn, Ronald G. Young, Dickon Weiss, Ray F. Dutton, Geoff S. Elkins, James W. Krummel, Paul B. Langenfelds, Ray Steele, L. Paul O'Doherty, Simon Xiang, Gao Massachusetts Institute of Technology. Joint Program on the Science & Policy of Global Change Xiang, Gao We present top-down constraints on global monthly N[subscript 2]O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well current observations can constrain the spatial distribution of global N[subscript 2]O emissions. The strategies include (1) a standard 4D-Var inversion at native model resolution (4° × 5°), (2) an inversion for six continental and three ocean regions, and (3) a fast 4D-Var inversion based on a novel dimension reduction technique employing randomized singular value decomposition (SVD). The optimized global flux ranges from 15.9 Tg N yr[superscript −1] (SVD-based inversion) to 17.5–17.7 Tg N yr[superscript −1] (continental-scale, standard 4D-Var inversions), with the former better capturing the extratropical N[subscript 2]O background measured during the HIAPER Pole-to-Pole Observations (HIPPO) airborne campaigns. We find that the tropics provide a greater contribution to the global N[superscript 2]O flux than is predicted by the prior bottom-up inventories, likely due to underestimated agricultural and oceanic emissions. We infer an overestimate of natural soil emissions in the extratropics and find that predicted emissions are seasonally biased in northern midlatitudes. Here, optimized fluxes exhibit a springtime peak consistent with the timing of spring fertilizer and manure application, soil thawing, and elevated soil moisture. Finally, the inversions reveal a major emission underestimate in the US Corn Belt in the bottom-up inventory used here. We extensively test the impact of initial conditions on the analysis and recommend formally optimizing the initial N[superscript 2]O distribution to avoid biasing the inferred fluxes. We find that the SVD-based approach provides a powerful framework for deriving emission information from N2O observations: by defining the optimal resolution of the solution based on the information content of the inversion, it provides spatial information that is lost when aggregating to political or geographic regions, while also providing more temporal information than a standard 4D-Var inversion. United States. National Oceanic and Atmospheric Administration (Grant NA13OAR4310086) United States. National Oceanic and Atmospheric Administration (Grant NA13OAR4310081) 2018-03-23T18:33:10Z 2018-03-23T18:33:10Z 2018-01 2017-11 2018-02-01T19:17:22Z Article http://purl.org/eprint/type/JournalArticle 1680-7324 1680-7316 http://hdl.handle.net/1721.1/114271 Wells, Kelley et al. “Top-down Constraints on Global N[subscript 2]O Emissions at Optimal Resolution: Application of a New Dimension Reduction Technique.” Atmospheric Chemistry and Physics 18, no. 2 (January 22, 2018): 735–756. http://dx.doi.org/10.5194/acp-18-735-2018 Atmospheric Chemistry and Physics Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/ application/pdf Copernicus Publications Copernicus Publications |
| spellingShingle | Wells, Kelley C. Millet, Dylan B. Bousserez, Nicolas Henze, Daven K. Griffis, Timothy J. Chaliyakunnel, Sreelekha Dlugokencky, Edward J. Saikawa, Eri Prinn, Ronald G. Young, Dickon Weiss, Ray F. Dutton, Geoff S. Elkins, James W. Krummel, Paul B. Langenfelds, Ray Steele, L. Paul O'Doherty, Simon Xiang, Gao Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title | Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title_full | Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title_fullStr | Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title_full_unstemmed | Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title_short | Top-down constraints on global N[subscript 2]O emissions at optimal resolution: application of a new dimension reduction technique |
| title_sort | top down constraints on global n subscript 2 o emissions at optimal resolution application of a new dimension reduction technique |
| url | http://hdl.handle.net/1721.1/114271 |
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