Modeling uncertainties for tropospheric nitrogen dioxide columns affecting satellite-based inverse modeling of nitrogen oxides emissions

Abstract

Errors in chemical transport models (CTMs) interpreting the relation between space-retrieved tropospheric column densities of nitrogen dioxide (NO<sub>2</sub>) and emissions of nitrogen oxides (NO<sub>x</sub>) have important consequences on the inverse modeling. They are however difficult to quantify due to lack of adequate in situ measurements, particularly over China and other developing countries. This study proposes an alternate approach for model evaluation over East China, by analyzing the sensitivity of modeled NO<sub>2</sub> columns to errors in meteorological and chemical parameters/processes important to the nitrogen abundance. As a demonstration, it evaluates the nested version of GEOS-Chem driven by the GEOS-5 meteorology and the INTEX-B anthropogenic emissions and used with retrievals from the Ozone Monitoring Instrument (OMI) to constrain emissions of NO<sub>x</sub>. The CTM has been used extensively for such applications. Errors are examined for a comprehensive set of meteorological and chemical parameters using measurements and/or uncertainty analysis based on current knowledge. Results are exploited then for sensitivity simulations perturbing the respective parameters, as the basis of the following post-model linearized and localized first-order modification. It is found that the model meteorology likely contains errors of various magnitudes in cloud optical depth, air temperature, water vapor, boundary layer height and many other parameters. Model errors also exist in gaseous and heterogeneous reactions, aerosol optical properties and emissions of non-nitrogen species affecting the nitrogen chemistry. Modifications accounting for quantified errors in 10 selected parameters increase the NO<sub>2</sub> columns in most areas with an average positive impact of 18% in July and 8% in January, the most important factor being modified uptake of the hydroperoxyl radical (HO<sub>2</sub>) on aerosols. This suggests a possible systematic model bias such that the top-down emissions will be overestimated by the same magnitude if the model is used for emission inversion without corrections. The modifications however cannot eliminate the large model underestimates in cities and other extremely polluted areas (particularly in the north) as compared to satellite retrievals, likely pointing to underestimates of the a priori emission inventory in these places with important implications for understanding of atmospheric chemistry and air quality. Note that these modifications are simplified and should be interpreted with caution for error apportionment

A new mechanism for atmospheric mercury redox chemistry: implications for the global mercury budget

“…GEOS-Chem concentrations of NO 2 and H 2 O 2 (proxy for HO 2 ) have been evaluated successfully in a number of aircraft campaigns (Martin et al, 2006;Hudman et al, 2007;Singh et al, 2007;Lin and McElroy, 2010;Mao et al, 2010;Travis et al, 2016). GEOS-Chem NO 2 columns have also been evaluated against satellite observations over China (Lin et al, 2012), North America (e.g., Lamsal et al, 2014), and Africa (Marais et al, 2012). Fast Hg 0 oxidation in the polar spring boundary layer is simulated by specifying high BrO concentrations when conditions for temperature, sea ice cover, sunlight, and atmospheric stability are met .…”

Global high-resolution simulations of tropospheric nitrogen dioxide using CHASER V4.0

“…Lin et al (2012) and Stavrakou et al (2013) suggested that the uptake of HO 2 on aerosols is the most important factor but remains largely uncertain. CHASER includes simplified NO x -VOC chemistry related to PANs and isoprene nitrates (Sudo et al, 2002).…”

“…Representations of meteorological parameters, such as cloud optical depth, temperature, water vapor, PBL height, and relevant transport and chemical processes, are also important in tropospheric NO 2 simulations (Lin et al, 2012). Because we employed an AGCM-CTM online coupling system, meteorological fields are simulated explicitly at each model resolution.…”

Improved simulation of tropospheric ozone by a global-multi-regional two-way coupling model system

“…Based on J.-T. Lin et al (2012), we have modified the chemical mechanism as follows. The reaction constants for OH + NO 2 follow Mollner et al (2010) for low-and high-pressure limits, i.e., k 0 = 1.48 × 10 −30 × (T /300) −3 cm 6 molecule −2 s −1 , and k inf = 2.58 × 10 −11 cm 3 molecule −1 s −1 .…”

“…Many of these models tend to overestimate the tropospheric ozone in the Northern Hemisphere Stevenson et al, 2006;Fiore et al, 2009;Reidmiller et al, 2009;Young et al, 2013;Parrish et al, 2014). Previous studies have suggested various sources of model biases in emissions, chemical mechanisms, meteorological inputs and model resolutions Lin et al, 2008;Weaver et al, 2009; J.-T. Lin et al, 2012;Doherty et al, 2013;Parrish et al, 2014;Fiore et al, 2014;Fu et al, 2015;Monks et al, 2015). Lack of capability in representing small-scale processes not resolved by the coarse-resolution global models may be an important factor for model biases, whereas the quantitative effect is much less clear, especially for the global effect of processes at scales below 100 km.…”