Inverse modeling of SO2 and NOx emissions over China using multisensor satellite data – Part 1: Formulation and sensitivity analysis

Wang, Yi; Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Qu, Zhen; Yang, Kai

Inverse modeling of SO2 and NOx emissions over China using multisensor satellite data – Part 1: Formulation and sensitivity analysis

dc.contributor.author	Wang, Yi
dc.contributor.author	Wang, Jun
dc.contributor.author	Xu, Xiaoguang
dc.contributor.author	Henze, Daven K.
dc.contributor.author	Qu, Zhen
dc.contributor.author	Yang, Kai
dc.date.accessioned	2020-07-15T18:37:49Z
dc.date.available	2020-07-15T18:37:49Z
dc.date.issued	2020-06-05
dc.description.abstract	SO₂ and NO₂ observations from the Ozone Mapping and Profiler Suite (OMPS) sensor are used for the first time in conjunction with the GEOS-Chem adjoint model to optimize both SO₂ and NOₓ emission estimates over China for October 2013. Separate and joint (simultaneous) optimizations of SO₂ and NO₂ emissions are both conducted and compared. Posterior emissions, compared to the prior, yield improvements in simulating columnar SO₂ and NO₂, in comparison to measurements from the Ozone Monitoring Instrument (OMI) and OMPS. The posterior SO₂ and NOₓ emissions from separate inversions are 748 Gg S and 672 Gg N, which are 36 % and 6 % smaller than prior MIX emissions (valid for 2010), respectively. In spite of the large reduction of SO₂ emissions over the North China Plain, the simulated sulfate–nitrate–ammonium aerosol optical depth (AOD) only decrease slightly, which can be attributed to (a) nitrate rather than sulfate as the dominant contributor to AOD and (b) replacement of ammonium sulfate with ammonium nitrate as SO₂ emissions are reduced. For joint inversions, both data quality control and the weight given to SO₂ relative to NO₂ observations can affect the spatial distributions of the posterior emissions. When the latter is properly balanced, the posterior emissions from assimilating OMPS SO₂ and NO₂ jointly yield a difference of −3 % to 15 % with respect to the separate assimilations for total anthropogenic SO₂ emissions and ±2 % for total anthropogenic NOₓ emissions; but the differences can be up to 100 % for SO₂ and 40 % for NO₂ in some grid cells. Improvements on SO₂ and NO₂ simulations from the joint inversions are overall consistent with those from separate inversions. Moreover, the joint assimilations save ∼ 50 % of the computational time compared to assimilating SO₂ and NO₂ separately in a sequential manner of computation. The sensitivity analysis shows that a perturbation of NH3 to 50 % (20 %) of the prior emission inventory can (a) have a negligible impact on the separate SO₂ inversion but can lead to a decrease in posterior SO₂ emissions over China by −2.4 % (−7.0 %) in total and up to −9.0 % (−27.7 %) in some grid cells in the joint inversion with NO₂ and (b) yield posterior NOₓ emission decreases over China by −0.7 % (−2.8 %) for the separate NO₂ inversion and by −2.7 % (−5.3 %) in total and up to −15.2 % (−29.4 %) in some grid cells for the joint inversion. The large reduction of SO₂ between 2010 and 2013, however, only leads to ∼ 10 % decrease in AOD regionally; reducing surface aerosol concentration requires the reduction of emissions of NH₃ as well.	en_US
dc.description.sponsorship	This research is supported by the National Aeronautics and Space Administration (NASA) through the Aura program managed by Kenneth W. Jucks, the ACMAP program (grant numbers: NNX17AF77G and 80NSSC19K0950) managed by Richard Eckman, and the TEMPO project as part of NASA's Earth Venture program (grant number SV7-87011 subcontracted from the Harvard–Smithsonian Observatory to The University of Iowa). We acknowledge the computational support from the High-Performance Computing group at The University of Iowa and Charles O. Stanier from The University of Iowa for insightful comments on the analysis of SO₂ and NO₂ lifetimes. This research has been supported by NASA (grant nos. NNX17AF77G, 80NSSC19K0950, and SV7-87011).	en_US
dc.description.uri	https://www.atmos-chem-phys.net/20/6631/2020/	en_US
dc.format.extent	20 pages	en_US
dc.genre	journal articles	en_US
dc.identifier	doi:10.13016/m2kt0f-wjbg
dc.identifier.citation	Yi Wang et al., Inverse modeling of SO2 and NOx emissions over China using multisensor satellite data – Part 1: Formulation and sensitivity analysis, Atmos. Chem. Phys., 20, 6631–6650, 2020 https://doi.org/10.5194/acp-20-6631-2020	en_US
dc.identifier.uri	https://doi.org/10.5194/acp-20-6631-2020
dc.identifier.uri	http://hdl.handle.net/11603/19159
dc.language.iso	en_US	en_US
dc.publisher	Copernicus Publications	en_US
dc.relation.isAvailableAt	The University of Maryland, Baltimore County (UMBC)
dc.relation.ispartof	UMBC Physics Department Collection
dc.relation.ispartof	UMBC Faculty Collection
dc.relation.ispartof	UMBC Joint Center for Earth Systems Technology (JCET)
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dc.rights	Attribution 4.0 International	*
dc.rights.uri	https://creativecommons.org/licenses/by/4.0/	*
dc.title	Inverse modeling of SO2 and NOx emissions over China using multisensor satellite data – Part 1: Formulation and sensitivity analysis	en_US
dc.type	Text	en_US