An Observation‐Based Correction for Aerosol Effects on Nitrogen Dioxide Column Retrievals Using the Absorbing Aerosol Index

Cooper, M. J.; Martin, Randall V.; Hammer, Melanie S.; McLinden, Chris A.

doi:10.1029/2019gl083673

Cited by 7 publications

(5 citation statements)

References 97 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aerosol effects on the scattering weights are not taken into consideration. Based on radiative transfer calculations and satellite-based aerosol products, Y. Jung et al (2019) and Cooper et al (2019) observed small changes (< 10 %) in air mass factors (AMFs) with and without considering the aerosol impacts in Europe in springtime. This tendency likely results from a low aerosol optical depth.…”

Section: Measurements Modeling and Methodsmentioning

confidence: 99%

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

et al. 2021

View full text Add to dashboard Cite

Abstract. Questions about how emissions are changing during the COVID-19 lockdown periods cannot be answered by observations of atmospheric trace gas concentrations alone, in part due to simultaneous changes in atmospheric transport, emissions, dynamics, photochemistry, and chemical feedback. A chemical transport model simulation benefiting from a multi-species inversion framework using well-characterized observations should differentiate those influences enabling to closely examine changes in emissions. Accordingly, we jointly constrain NOx and VOC emissions using well-characterized TROPOspheric Monitoring Instrument (TROPOMI) HCHO and NO2 columns during the months of March, April, and May 2020 (lockdown) and 2019 (baseline). We observe a noticeable decline in the magnitude of NOx emissions in March 2020 (14 %–31 %) in several major cities including Paris, London, Madrid, and Milan, expanding further to Rome, Brussels, Frankfurt, Warsaw, Belgrade, Kyiv, and Moscow (34 %–51 %) in April. However, NOx emissions remain at somewhat similar values or even higher in some portions of the UK, Poland, and Moscow in March 2020 compared to the baseline, possibly due to the timeline of restrictions. Comparisons against surface monitoring stations indicate that the constrained model underrepresents the reduction in surface NO2. This underrepresentation correlates with the TROPOMI frequency impacted by cloudiness. During the month of April, when ample TROPOMI samples are present, the surface NO2 reductions occurring in polluted areas are described fairly well by the model (model: −21 ± 17 %, observation: −29 ± 21 %). The observational constraint on VOC emissions is found to be generally weak except for lower latitudes. Results support an increase in surface ozone during the lockdown. In April, the constrained model features a reasonable agreement with maximum daily 8 h average (MDA8) ozone changes observed at the surface (r=0.43), specifically over central Europe where ozone enhancements prevail (model: +3.73 ± 3.94 %, +1.79 ppbv, observation: +7.35 ± 11.27 %, +3.76 ppbv). The model suggests that physical processes (dry deposition, advection, and diffusion) decrease MDA8 surface ozone in the same month on average by −4.83 ppbv, while ozone production rates dampened by largely negative JNO2[NO2]-kNO+O3[NO][O3] become less negative, leading ozone to increase by +5.89 ppbv. Experiments involving fixed anthropogenic emissions suggest that meteorology contributes to 42 % enhancement in MDA8 surface ozone over the same region with the remaining part (58 %) coming from changes in anthropogenic emissions. Results illustrate the capability of satellite data of major ozone precursors to help atmospheric models capture ozone changes induced by abrupt emission anomalies.

show abstract

Section: Measurements Modeling and Methodsmentioning

confidence: 99%

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Aerosols can also contribute to uncertainty in air mass factor calculations, as a reduction in anthropogenic scattering aerosols during lockdowns may reduce air mass factors leading an underestimation of the NO 2 change 62,63 . However, this is likely to be a minor source of uncertainty in estimated NO 2 changes due to lockdown, because aerosol concentration changes were small in most regions 49 and a reduction in aerosol concentration of 10% translates to an uncertainty in NO 2 of less than 5% 64 . Additional uncertainty (σ Ω max ) may arise from the choice of the Ω max parameter (described in the Supplementary Information), particularly in regions where there are insufficient ground-monitor data for constraining Ω max .…”

Section: Limitations and Sources Of Uncertaintymentioning

confidence: 99%

Global fine-scale changes in ambient NO2 during COVID-19 lockdowns

Cooper

Martin

Hammer

et al. 2022

Nature

Self Cite

150

View full text Add to dashboard Cite

Nitrogen dioxide (NO2) is an important contributor to air pollution and can adversely affect human health1–9. A decrease in NO2 concentrations has been reported as a result of lockdown measures to reduce the spread of COVID-1910–20. Questions remain, however, regarding the relationship of satellite-derived atmospheric column NO2 data with health-relevant ambient ground-level concentrations, and the representativeness of limited ground-based monitoring data for global assessment. Here we derive spatially resolved, global ground-level NO2 concentrations from NO2 column densities observed by the TROPOMI satellite instrument at sufficiently fine resolution (approximately one kilometre) to allow assessment of individual cities during COVID-19 lockdowns in 2020 compared to 2019. We apply these estimates to quantify NO2 changes in more than 200 cities, including 65 cities without available ground monitoring, largely in lower-income regions. Mean country-level population-weighted NO2 concentrations are 29% ± 3% lower in countries with strict lockdown conditions than in those without. Relative to long-term trends, NO2 decreases during COVID-19 lockdowns exceed recent Ozone Monitoring Instrument (OMI)-derived year-to-year decreases from emission controls, comparable to 15 ± 4 years of reductions globally. Our case studies indicate that the sensitivity of NO2 to lockdowns varies by country and emissions sector, demonstrating the critical need for spatially resolved observational information provided by these satellite-derived surface concentration estimates.

show abstract

“…Both OMI NO 2 retrievals employed in this study use NO 2 vertical shape factors from coarse resolution simulations, and therefore are biased low compared to in-situ measurements [Goldberg et al, 2017]. These retrievals also have not explicitly accounted for the 400 aerosol optical effects, which are demonstrated to degrade the accuracy of NO 2 column concentrations [Chimot et al, 2016;Liu et al, 2019;Cooper et al, 2019]. The differences in the magnitude of ozone concentrations from GC-adj and GCv12 reflect the impact of other species emissions and chemical mechanisms on the bias of ozone simulations.…”

Section: Discussionmentioning

confidence: 99%

Improving NO2 and ozone simulations through global NOx emission inversions

Henze

Cooper

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Tropospheric ozone simulations have large uncertainties, but their biases, seasonality and trends can be improved with more accurate estimates of precursor gas emissions. We perform global top-down estimates of monthly NOx emissions using two OMI NO2 retrievals (NASAv3 and DOMINOv2) from 2005 to 2016 through a hybrid 4D-Var/mass balance inversion. The 12-year averages of regional NOx budgets from the NASA posterior emissions are 37 % to 53 % smaller than the DOMINO posterior. Compared to surface NO2 measurements, GEOS-Chem adjoint NO2 simulations using the DOMINO posterior NOx emissions have smaller biases in China (by 15 %) and the US (by 22 %), but NO2 trends have more consistent decreases (by 26 %) with the measurements (by 32 %) in the US from 2006 to 2016 when using the NASA posterior. The two posterior NOx emissions datasets have different strengths with respect to simulation of ozone concentrations. Simulations using NASA-based emissions provide better agreement for polluted conditions. Ozone from these shows the highest correlation (R2 = 0.88) with annual MDA8 ozone trends and alleviates the double peak in the prior simulation of global ozone seasonality. The DOMINO-based emissions, on the other hand, are better for simulating ozone at remote sites, making them well-suited to generation of boundary conditions for regional models, and in capturing the interannual variability of daytime-average (R2 = 0.72–0.81) and 24-hour average (R2 = 0.88–0.96) surface ozone. We recommend using NOx emission datasets that have the best performance in the corresponding spatial domain and temporal focus to improve ozone simulations.

show abstract

An Observation‐Based Correction for Aerosol Effects on Nitrogen Dioxide Column Retrievals Using the Absorbing Aerosol Index

Cited by 7 publications

References 97 publications

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

Global fine-scale changes in ambient NO2 during COVID-19 lockdowns

Improving NO<sub>2</sub> and ozone simulations through global NO<sub><i>x</i></sub> emission inversions

Contact Info

Product

Resources

About

An Observation‐Based Correction for Aerosol Effects on Nitrogen Dioxide Column Retrievals Using the Absorbing Aerosol Index

Cited by 7 publications

References 97 publications

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

Unraveling pathways of elevated ozone induced by the 2020 lockdown in Europe by an observationally constrained regional model using TROPOMI

Global fine-scale changes in ambient NO2 during COVID-19 lockdowns

Improving NO&lt;sub&gt;2&lt;/sub&gt; and ozone simulations through global NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; emission inversions

Contact Info

Product

Resources

About

Improving NO<sub>2</sub> and ozone simulations through global NO<sub><i>x</i></sub> emission inversions