Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

Wecht, K.; Jacob, Daniel J.; Sulprizio, Melissa P.; Santoni, G. W.; Wofsy, Steven C.; Parker, Robert J.; Bösch, H.; Worden, J.

doi:10.5194/acp-14-8173-2014

Cited by 102 publications

(167 citation statements)

References 37 publications

(43 reference statements)

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“…For example, several top-down studies indicate that the California state inventory is likely too low by a factor of 1.2 to 1.9 (Jeong et al, 2013Wecht et al, 2014b), and several top-down studies estimate emissions for oil and gas drilling regions of Utah and Colorado that are up to 3 times bottom-up estimates (e.g., Karion et al, 2013;Pétron et al, 2014). Overall, total US CH 4 emissions are likely ∼50 % larger than estimated by EDGAR or the US EPA Wecht et al, 2014a;Turner et al, 2015).…”

Section: Impact Of Recent Advancesmentioning

confidence: 98%

“…However, the relative magnitude of the source sectors in any one grid box will be the same as in the bottom-up inventory. Wecht et al (2014b) and Jeong et al (2016) leverage this strategy to estimate CH 4 emissions for California using aircraft and tower-based observations, respectively. Like Zhao et al (2009) and Jeong et al (2013), they also find higher emissions from agriculture relative to EDGAR.…”

Section: State-and National-scale Inverse Modelingmentioning

confidence: 99%

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Constraining sector-specific CO2 and CH4 emissions in the US

Miller

Michalak

2017

Atmos. Chem. Phys.

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Abstract. This review paper explores recent efforts to estimate state-and national-scale carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from individual anthropogenic source sectors in the US. Nearly all state and national climate change regulations in the US target specific source sectors, and detailed monitoring of individual sectors presents a greater challenge than monitoring total emissions. We particularly focus on opportunities to synthesize disparate types of information on emissions, including emission inventory data and atmospheric greenhouse gas data.We find that inventory estimates of sector-specific CO 2 emissions are sufficiently accurate for policy evaluation at the national scale but that uncertainties increase at state and local levels. CH 4 emission inventories are highly uncertain for all source sectors at all spatial scales, in part because of the complex, spatially variable relationships between economic activity and CH 4 emissions. In contrast to inventory estimates, top-down estimates use measurements of atmospheric mixing ratios to infer emissions at the surface; thus far, these efforts have had some success identifying urban CO 2 emissions and have successfully identified sector-specific CH 4 emissions in several opportunistic cases. We also describe a number of forward-looking opportunities that would aid efforts to estimate sector-specific emissions: fully combine existing top-down datasets, expand intensive aircraft measurement campaigns and measurements of secondary tracers, and improve the economic and demographic data (e.g., activity data) that drive emission inventories. These steps would better synthesize inventory and topdown data to support sector-specific emission reduction policies.

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Section: Impact Of Recent Advancesmentioning

confidence: 98%

Section: State-and National-scale Inverse Modelingmentioning

confidence: 99%

Constraining sector-specific CO2 and CH4 emissions in the US

Miller

Michalak

2017

Atmos. Chem. Phys.

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“…This approach therefore implicitly assumes that the sign of the a priori flux (which can be negative over the ocean) is correct for each model grid square. The GEOS-Chem adjoint has previously been applied to a wide range of inverse problems for atmospheric composition, including constraining sources and sinks of long-lived greenhouse gases such as CO 2 (Deng et al, 2014;Liu et al, 2014;Deng et al, 2015;Liu et al, 2015), methane (Wecht et al, 2014;Turner et al, 2015a), and N 2 O (Wells et al, 2015), as well as aerosols and reactive trace gases (e.g., Henze et al, 2007;Kopacz et al, 2009;Wells et al, 2014).…”

Section: Standard 4d-var Inversionmentioning

confidence: 99%

Top-down constraints on global N2O emissions at optimal resolution: application of a new dimension reduction technique

et al. 2018

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Abstract. We present top-down constraints on global monthly N 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 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 −1 (SVDbased inversion) to 17.5-17.7 Tg N yr −1 (continental-scale, standard 4D-Var inversions), with the former better capturing the extratropical N 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 2 O flux than is predicted by the prior bottomup 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 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 N 2 O 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.

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“…Both LPDM and mass balance are limited to linear tracer problems where observations are recorded under specific meteorological conditions. Wecht et al (2014) used GEOS-Chem in an analytical inversion to compare constraints from the CalNex aircraft measurements with those from present and future satellite observations of CH 4 throughout California. Although an analytical inversion does not require an adjoint, the approach is limited, computationally, to constraining only a few sources, which imposes aggregation error (Mao et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

Guerrette

Henze

2017

Atmos. Chem. Phys.

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Abstract. Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental four-dimensional variational (4D-Var) capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB) and anthropogenic black carbon (BC) aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB) field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network on 22, 23, and 24 June 2008. We consider three BB inventories, including Fire INventory from NCAR (FINN) v1.0 and v1.5 and Quick Fire Emissions Database (QFED) v2.4r8. On 22 June, aircraft observations are able to reduce the spread between a customized QFED inventory and FINNv1.0 from a factor of 3.5 (×3.5) to only ×2.1. On 23 and 24 June, the spread is reduced from ×3.4 to ×1.4. The posterior corrections to emissions are heterogeneous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The US EPA's 2005 National Emissions Inventory (NEI05) is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is reduced by ×2, where highway sources dominate, while inland sources are increased near Barstow by ×5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and by up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly limited to sources close to observations. We find that the 22 June aircraft observations are able to constrain approximately 14 degrees of freedom of signal (DOF), while surface and aircraft observations together on 23/24 June constrain 23 DOF. Improving hourly-to daily-scale concentration predictions of BC and other aerosols during BB events will require more comprehensive and/or targeted measurements and a more complete accounting of sources of error besides the emissions.

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Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

Cited by 102 publications

References 37 publications

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Top-down constraints on global N<sub>2</sub>O emissions at optimal resolution: application of a new dimension reduction technique

Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

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Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

Cited by 102 publications

References 37 publications

Constraining sector-specific CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; emissions in the US

Constraining sector-specific CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; emissions in the US

Top-down constraints on global N&lt;sub&gt;2&lt;/sub&gt;O emissions at optimal resolution: application of a new dimension reduction technique

Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

Contact Info

Product

Resources

About

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Top-down constraints on global N<sub>2</sub>O emissions at optimal resolution: application of a new dimension reduction technique